Nr3en2017

CONTENTS

Ioan-Lucian BOLUNDUŢ Apuseni Mountains gold mining during the Middle Ages

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Ioan BUD, Iosif Ioan PAȘCA, Simona DUMA, Dorel GUȘAT The analysis of the muddy flow and acid drainage risk at Șuior Mining Perimeter, Maramureș County

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Crina-Adriana DRĂGĂNESCU (GURICĂ) Analysis of the influence of the mining activities in Rovinari Mining Basin upon the functioning of Rovinari Thermal Power Plant in fully safety

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Ileana PASCU Research regarding the stability of A1 motorway in the Lugoj - Deva section, lot 2, km: 27+620÷47+090

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Caşen PANAITESCU, Claudia Georgeta NICULAE Aspects regarding the optimization of the use of horizontal centrifugal compressors

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AGIR PRIZE - 2016 Mining within Romania’s sustainable development

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APUSENI MOUNTAINS GOLD MINING DURING THE MIDDLE AGES Ioan-Lucian BOLUNDUŢ* Abstract: The paper presents the organization and legal framework of gold mining in the Apuseni Mountains in the Middle Ages. At that time, the miners enjoyed a series of privileges granted by the Transylvanian voievodes or Hungarian kings. Mining technology refers to tools and installations intended to transport ore and sterile in the galleries, water evacuation, ventilation of workplaces and grinding the auriferous ore.

Key words: gold mining in the Middle Ages, organization of mining, mining methods 1. Introduction As it is known, the Romans captured from the Dacians 165.5 ton gold and 331 ton silver, and during the 165 years of occupation they extracted an additional amount of 500 ton gold and 950 ton silver.

After the Romans withdrew from Dacia, the entire social-economic course of life went back to its rural character. Economy turned back to growing sheep, to extensive agriculture, craftsmanship declined, acquiring a predominantly household character.

Mining was no exception. The local population used metals to make agricultural tools, arms and household goods. Auriferous mining in the Apuseni Mountains was probably limited to the exploitation of alluvium gold along rivers, and exploitation of meagre seams, close to surface, that were not worth to the Romans. It is hard to believe that the miners left behind would have abandoned their occupation and would have turned to sheepherding; agriculture couldn’t have been an option. Gold and silver was potent money in those unstable times as well, about which we know little.

The mining technology of the Romans was so advanced, that in the following 1,500 years it remained almost unchanged, not only in our country but in Europe as well. In our country, barbarian incursions stopped the Dacian-Roman civilization for almost a millennium, the so-called dark millennium having been instated.

2. Mining organization [3] Exploitation of precious metals in the Apuseni Mountains restarted in the 8th century, after the Slav people had been assimilated, the proof being Zlatna toponym, which replaced the name Ampelum, given to this ancient mining centre by the Romans, zlato meaning gold in Slavic. No documents are known referring to the social-economic organization of the people in the auriferous region of the Apuseni Mountains in that period, but one can assume that they lived according to the ancient

* Prof.Ph.D.eng., University of Petroșani 2

customary law. Alongside with the pre-state feudal structures (princedoms and voievode’s domains), the interest towards mining regions increased, they became feudal domains, and their inhabitants became serfs to the crown. Over these pre-state structures within the Carpathian Arch, with emerging rudimentary organizations of life, the Hungarians stormed in. From the 10th century on, the Romanian territories began to be enclosed in the medieval kingdom of Hungary, which adopted a policy of colonization, settling the Szeklers in the east of the province, and the Transylvanian Saxons in the south and around Bistriţa. The colonists’ mission was defending the borders and putting to good use the economic resources of the autonomous voievode’s domain. In the year 1210 the occupation of Transylvania by the Magyars was finished by conquering Ţara Bârsei.

The first written documents appeared in this period, establishing many aspects of the socialeconomic life of the period, among which mining activity.

Such a document is the Letter of Privileges given by King Bela the Fourth of Hungary (1235–1270), in the year 1255, for the miners of Besztercebánya (Banská–Bystrica from today), granting them a series of privileges. The document is also important for the auriferous mining in the Apuseni Mountains, since German miners from Besztercebánya and Körmöczbánya were brought to Zlatna, Abrud and Bucium. They kept the rights given by Bela the Fourth and fought for a long time to maintain them. The Letter of Privileges of 1255 states that the miners of the area mentioned above had economic, legal and religious advantages, based on which they could run a more sustained economic activity, compared to the other inhabitants. They could prospect and exploit noble metals underground and along the rivers, but they had the obligation to pay to the regal tax administration the eighth part of the gold and the tenth part of the silver extracted, and in case metaliferous seams had been discovered, the king could take possession of the respective terrain.

Similarly, the miners were exempted from customs taxes for goods of strict necessity and financial and Revista Minelor / Mining Revue - no. 3 / 2017

military obligations to local nobility. The privileges were acknowledged and reconfirmed by Bela the Fourth’, Laszlo the Fourth’ (1287), and Andras the Second’s (1291) heirs. We should also mention that Bela the Fourth had previously granted the same privileges to the Saxons in Cricău and Ighiu, by a document (February the 12th, 1238), signed at, Archita (village belonging now to Vânători, Mureş County), established by the Saxons around the year 1200. The Saxons of Cricău and Ighiu received the right to exploit gold at Zlatna and Vulcoi.

Carol Robert de Anjou was the one that ensured a real development of mining in Transylvania, by developing mining regulations, through a Letter of Privileges, signed at Visegrád, in 1327. Unlike the privileges given by Bela the Fourth, referring only to certain mining communities, those granted by Carol Robert de Anjou covered all the miners in the Kingdom of Hungary. Moreover, the terrains where precious metals had been discovered did no longer become the king’s property, they remained in the property of the owners, with the condition that 2/3 of the “urbura” be deposited in the regal Treasury, the other one third remaining to the owner. The gold produced in the four mining centres of Apuseni Mountains, Abrud, Baia de Arieş, Zlatna and Baia de Criş, had to be exchanged in the regal office in Sibiu, at the official price fixed by the king. As a result of making miners co-interested, auriferous mining in the Apuseni Mountains raised up, many landowners starting a campaign of exploitation of the resources of the underground.

The privileges granted to the miners by Carol Robert de Anjou were reconfirmed by Ludovic I de Anjou (1351), Sigismund de Luxemburg (1405), Matei Corvin (1486), Vladislav II Iagello (1492) and Ludovic II Iagello (1523).

Based on these regulations, the functioning of the mines was submitted to a process of organization. A document dated September 20th, 1347, of the Hungarian Chancellor, for the miners of Baia Mare, shows very interesting data with this in view. Thus, the community of workers, together with the judge and the jury of the place to which the mine belonged, (today’s mayor and councillors), chose for a year a knowledgeable magister of the mountain (chief of mine), responsible for the good functioning of the mine. In his turn, he appointed the “steigers” (today’s foremen) and gold examiners (today’s probers), with the approval of the judge and the jury. The “steigers” supervised the work in the mine and collected the “urbura” for the king, and the gold researchers took samples from the faces, establishing the metal content of the ore. The regulation stipulated severe punishments for those who avoided acquitting the “urbura”, but also defended the miners in case of abuses.

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A report on organizing auriferous mining and production of noble metals in Transylvania in the 15th and 16th centuries of Paul Bornemisza (Catholic Bishop of Veszprém) and Georg Werner, commissioners to King Ferdinand the First of Bohemia and Hungary (1526–1564), sent to analyze the worrying situation of the mines of that area, shows interesting data. In the first half of the 16th century, gold production in Transylvania decreased significantly. Mines became deeper and the methods of that time could hardly handle the evacuation of underground water, and in many cases the producers were too poor to cope with the situation. The report shows that Transylvania was richer in gold than in silver, but out of the four important mines only the one of Baia de Arieş belonged to the king, and this preponderantly extracted silver. The mines in Zlatna and Abrud, very rich in gold, belonged to Alba Iulia, Baia de Criş mine was submitted to Şiria, belonging to Matei Corvin. The decline in gold production was caused by the lack of cash of the Exchange office in Sibiu. The clandestine money changers, called gozars by the population in the Apuseni Mountains, dealt heavily with gold, eluding the regal monopoly and making huge profit. This is the reason why the small gold producers are scarce on the exchange tables, although they made the greatest gold production. Usually the gold exchange was leased to the Saxons in Sibiu, for 4,000–5,000 Florin per year, sometimes even more. By the end of the 15th century, the gold exchange was approximately 350 kg/year, decreasing to 300 kg in 1552. In order to correct the situation, the Transylvanian princes took a series of measures, among which reconfirmation of the old privileges of the mining towns, secularization of the bishop domains of Alba Iulia and introduction of foreign capital in auriferous mining.

3. Mining technology [1,3] Interesting data referring to the technology applied in the gold mines near Zlatna and Abrud in the second half of the 16th century are displayed by foreign travellers visiting these places. Thus, the French Pierre Lescalopier, who visited Transylvania in 1574 visited Zlatna gold mine, where “one goes far in under a high mountain, [Vulcoi – n.o.]. The miners take out some rock from here, then they burn it first as it were gypsum, then they grind it in a water mill that throws the burnt stones in a one foot wide, two pole long wooden gutter, where the rock is crushed with thick pestles that rise and fall one at a time, one after the other.

The gravel is slowly carried by water, and spread over thick burlaps, laid out on a slightly inclined floor over a large trough. The gold is caught up on 3

these burlaps, and what is not caught up falls in the trough, and the water flows down. Two times a day the miners raise these burlaps, wash them in other troughs, then take out the bits and pieces on large wooden cymbals, which then are shaken little by little, until the gold gathers in one side, and the useless sand on the other side of the cymbal. When a certain amount of gravel with gold is amassed, they put a little quicksilver in an alembic where, by the action of fire, the quicksilver reduces the gold to bars, then the quicksilver evaporate” [7, pp.

140–143].

The Austrian nobleman Felician de Herberstein, who took on a lease the goldmines in Cavnic next to Baia Mare, visited the mining region of the Apuseni Mountains by the end of the year 1585, at the request of the king of Poland Ştefan Báthory (1575–1586), drawing up a thorough report regarding the mines of Bucium, Almaş, Ruda and Băiţa. The report gives interesting details referring to the technology of extraction and processing of gold ores there, completing the information in the report of the imperial commissioners sent to Transylvania in 1552. Herberstein’s report might have been a little biased, presenting the situation more worthless than it was in reality, considering his intention to take these mines on a lease, which happened indeed. After his death, the contract of lease was prolonged by Prince Sigismund Báthory by his diploma of July the 1st, 1591, given to Heberstein’s sons, Sigismund and Friedrich, where the villages affected to the mines were also mentioned. The contract was dissolved in the summer of 1597.

The most complete information related to ore extraction and processing in the middle of the 16th century were shown in detail by the German scientist Georg Agricola, Georg Bauer his real name (1494–1555), in his famous book De re metallica libri XII (On Mining and Metallurgy), published in 1556, shortly after the author’s death.

Written in Latin, the book was translated to German, with many errors in its content and language. In 1912 an excellent translation was made by the American mining engineer HerbertClark Hoover and his wife Lou Henry-Hoover; the mining engineer became later the president of the U.S.A. (1929–1933). A physician by profession, Agricola approached minerals little by little, treating his patients with mineralogical remedies, known in ancient literature; therefore he settled in Chemnitz, in the Metaliferous Mountains in Eastern Germany, very rich in nonferrous metals. There was a saying in those parts, “If a German throws a stone or dross after a cow, it might be more precious than the cow”. It was there that Agricola deepened his knowledge on mining and metallurgy, 4

being considered the father of mineralogy, and his book, De re metallica, with 273 illustrations, is a quintessence of all that had been known at that time about mining and metallurgy.

Clearly, Agricola visited the gold mines in the Apuseni Mountains, he mentioned more than once the gold extraction procedures from the ore applied in the Carpathians. At that time, gold was extracted and processed only in the Western Carpathians. Besides, Agricola mentioned Zlatna, Abrud and Baia de Criş in other two works related to mountains and mineralogy (De natura fossilium, libri III and De veteribus et novis metallis, libri II).

He also had good knowledge of the mining technology applied in the ancient world from the writings of Plinius the Old, whom he frequently mentioned. After 1,300 years, gold extraction methods remained the same, while mines had become deeper. In hard rock the method of fire and water was used, progress was only made in ore transportation, water evacuation and mine ventilation. Certainly, to grind auriferous ore stamps were used.

Wooden wagons had rectangular shape, the upper part being slightly narrower, fastened by and iron strips. At the lower part there were two metal shafts, and at their extremities wooden wheels were mounted. The wagons ran on wooden paths, and to avoid derailing, in the middle of one of the shafts, there was a guiding pivot that entered in the canal of the thick plank between the rails, which was also used by people to walk. The wagons were pushed from the back, full as well as empty. Since during the travel the wagons made a squeaking sound, like a puppy, the German miners called them hunt (Hund = dog), becoming hont in the language of the people living in the area.

The oldest wooden wagon in the world goes back to the 14th century, and had been discovered in the old mining workings in Ruda– Brad, together with the transport line and a switch, also made of wood. The original wagon is found at the Museum of Mining in Bochum (Deutches Bergbau-Museum), and the switch at the Museum of Transport in Berlin (Museum fur Verkehr und Technik). The line switch was invented around the year 1600 by the miners in Brad. Similar wagons were used in the mines in England, but only at the beginning of the 17th century, that is almost 300 years later.

Water evacuation was made by pumps with piston, manually driven by a handle or a balancing mechanism. In principle, such a pump was made up of a wooden cylinder, wherein a piston with several holes in it moved, and on its upper part there was a leather choke, attached to the piston in only one point. The lower part of the wooden cylinder had Revista Minelor / Mining Revue - no. 3 / 2017

several radial holes, by which water collected in a sump entered. At the descending stroke of the piston, manually driven by a rod with a handle or a balancer, water entered above the piston, through its holes. At the upstroke, the water weight pressed on the leather choke, which sealed the piston, so that water was lifted up to a flow gutter, being then discharged in a canal or in another intermediary sump. This principle is used nowadays to take out water from deep fountains in flat areas; instead of the piston, a long, cylindrical vessel is used, with diameter slightly smaller than that of the concrete fountain. At the descending movement, water enters by its perforated bottom, and when the vessel moves up, a rubber or leather choke seals the vessel, keeping the water inside.

Mine ventilation was made by rather ingenious methods, combining forcing ventilation with induced ventilation. In the first case, an iron circle reinforced barrel was used, mounted on a wooden duct that entered the ventilation shaft. The link between the barrel and the duct was made by a wooden disk, fixed to the duct by a square hole, allowing the free rotation of the barrel in both senses. The barrel rotated around a longitudinal axis, at the slightest wind, due to certain wings, always bringing the air entering window in the direction of the wind. This construction is known today as ventilation hat. The clean air forced itself in the ventilation shaft, flushing the underground mine workings, the vitiated air being evacuated afterwards to the surface through a secondary shaft.

a

a

b Fig. 1. Wooden wagon: a – in Agricola’s work; b – reconstitution

The length of the wooden cylinders was limited to 3–3,5 m, so that special drills could be used to make the holes. Usually, for higher water evacuation, two such cylinders were joined, one lengthening the other, and for a good sealing, a funnel shaped leather gasket was used, tied with the narrower part to the piston, the larger part sliding along the cylinder. In the medieval workings at Roşia Montană a 7 m long pump was found, with 22 cm outer diameter. It is kept at the Museum of Auriferous Mining at Roşia Montană.

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b Fig. 2. Water pumps with piston (Agricola): a – with handle; b – cu balancer

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a

when the windbag folded, and vice versa. The induced ventilation system was applied with all types of mine workings that had no second outlet, today it is called dead-end ventilation.

Grinding auriferous mineral wad made in Agricola’s time with stamps driven by the force of water. These installations were invented by the German miners in the 12th century, being taken over by the French miners (13th century) and the Polish (14th century). The miners in Transylvania also began using the stamps in the 16th century, first in the Apuseni Mountains, then in Baia Mare, taking over the craftsmanship from the German miners colonized there, especially after the privileges granted by Carol Robert de Anjou and reconfirmed by his heirs. The stamps revolutionized the gold extracting technology, replacing the pestle and grinders, remaining the only grinding tool until the coming about of the mills.

b Fig. 3. Mine ventilation methods (Agricola): a – forcing; b – induced

Induced procedure ensured the evacuation of the vitiated air from the mine workings with only one access way, simultaneously with the unrestricted entering of the clean air, by compensating the created depression, but it involved the use of a man to manually drive the installation. It was mainly made up of a chamber with leather windbag with creased walls (bellows), driven by a system of levers. The ventilation shaft had two compartments separated by tightly joined planks, one with a smaller section, to aspire vitiated air, and the other with a larger section, to let clean air come in. The windbag was mounted on a wooden rectangular funnel, and the worker actuated the leather windbag by a system of levers. Thus, the „stinking air“ (Agricola dixit) was aspired and evacuated into the atmosphere by the mouthpiece of the windbag, which folded due to the weight of a boulder mounted above. The windbag had two vents that closed and opened alternatively: the one of the mouthpiece closed when the vitiated air was aspired, and the one of the wooden funnel closed 6

a

b Fig. 4. Auriferous stamps: a – in Agricola’s work; b – scheme of principle

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4. Conclusions

References

After the Romans withdrew from Dacia, auriferous mining declined, due to the invasion of the migrant populations. Exploitation of precious metals restarted in the 8th century, after the assimilation of the Slavs and intensified in the 10th century, after the establishment of princedoms and voievode’s domains. Later, these pre-state formations were enclosed in the medieval Kingdom of Hungary. The Hungarian kings colonized the conquered territories, to protect the borders, and to put to good use the underground resources.

Miners were granted economical and legal privileges for the exploitation of precious metals from underground or alluvium, on the condition that they would pay part of the winnings as taxes.

The most important privileges were given in 1327

by Carol Robert de Anjou, by a mining regulation, which was reconfirmed by his heirs until the end of the Middle Ages.

As far as precious metal extraction technology from underground is concerned, it was very much like during the Roman period. Auxiliary mining activities experienced however innovations. Thus in the 16th century at Brad wooden wagons and switches were used for the first time in history, and manually driven piston pumps were used for water evacuation. Mines were ingeniously ventilated, using wind or manual actuation of a chamber with windbag. During this period auriferous stamps were used to grind ore. All these were described in detail by the German scientist Georg Agricola in his famous book On Mining and Metallurgy, but tools had also been discovered in the old mines in the Apuseni Mountains, being now exposed in museums.

1. Agricola, G. Despre minerit şi metalurgie (Traducere din limba germană), Editura SONER Company, Baia Mare, 1994.

2. Bauer, G. A rudai 12 apostol bányatársulat aranybányászyta, Bányászati és Kohászati Lapok, XXXVII/1904/2k, pp.

289–338, Budapest, 1904.

3. Bolunduţ, I.L. Monografia comunei Bucium–Alba, Editura ALTIP, Alba Iulia, 2017.

4. Bolunduţ, I.L. Gold Mining at Apuseni Mountains in Antiquity, Annals of University of Petroşani (Mining Engineering), Vol. 15, pp. 7–16, Universitas Publishing House, Petroşani, 2014.

5. Bolunduţ, I.L. Gold Mining at Bucium in Antiquity, The Sixth Balkan Mining Congress 20th – 23th September 2015, eProceedings, pp. 358–367, Petroşani, 2015, ISBN 978973-741-435-9.

6. Fodor, D. Pagini din istoria mineritului, Editura INFOMIN, Deva, 2005 7. Köleséri, S. Auraria Romano-Dacica, una cum Valachiae cisalutanae subterraneae descriptione, Sumptibus Ioan Michaelis Landerer, 1780, http://dspace.bcucluj.ro/handle/123456789/37 8. Maghiar, N., Olteanu, Şt.

Din istoria mineritului în România, Editura Ştiinţifică, Bucureşti, 1970.

9. Roman, B., Sîntimbrean, A., Wollmann, V. Aurarii din Munţii Apuseni, Editura Sport-Turism, Bucureşti, 1982.

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THE ANALYSIS OF THE MUDDY FLOW AND ACID DRAINAGE RISK AT ȘUIOR MINING PERIMETER, MARAMURES COUNTY Ioan BUD*, Iosif Ioan PAȘCA*, Simona DUMA*, Dorel GUȘAT* Abstract: Șuior mining perimeter closure involves risks related to water accumulation and evacuation. In the last time, explosive water and mud discharges occurred on Șuior - Baia Sprie tunnel, which drained to the lower operation level. Șuior Mine presents a distinctive feature compared to other mines, emphasized through combined methods for ores exploitation, in open pit and underground (via subsidence methods) and having a mineralization powerfully reactive and perishable. All these lead to the risk of the build-up of acidic waters loaded with suspension in the form of bags under pressure, subsidence on the tunnel with 6.3 km length and unpredictable breaks of dams formed by subsidence.

Key words: risk, muddy flow, acid drainage, stability 1. Introduction Within Baia Mare mining perimeter, deposits are of hydrothermal type with gold-silver mineralization and complex sulphides vein type with thicknesses varying from tens of centimetres to tens of meters.

For operations on these ores it was used a complex underground mining works network which, in most cases, involved digging under a base level that was the path for water outlet and served for the transport of mining production.

Above the base level, the underground water was partially evacuated by gravity. Below the base level, throughout the mining activity duration, underground water has been evacuated by pumping.

After the mine closure, the water is no longer pumped, accumulating in operated empty spaces, existing the possibility to rise up to the base level or to move toward the surface through cracks, fractures and faults, falls or slips zones, sometimes getting an artesian waterbed character (fig. 1).

The presence of sulphides in the exploited space generates important oxidation reactions leading to a phenomenon called acid drainage, which has the effect of increased pollution of surface and underground water.

At Șuior mine, the operation was carried out by mixed methods, the upper part in open pit resulting in a sink, while the lower part involved a large network of underground mining works. The exploitation in open pit started at approximately +1,000 m and in underground, the opening work was carried out in levels of 50m up to the level +462 m.

The distinctive feature of Șuior mine consists in the fact that at the level +462m it has been performed a tunnel for the mining production transport and underground water evacuation to Baia Sprie. In this way, all water from the open pit area, from the slopes around the open pit and the underground water accumulates in the operated and collapsed spaces, draining toward the tunnel area.

Fig. 1. Opening and underground water evacuation system for a vein ore

* Technical University of Cluj-Napoca, North University Center of Baia Mare 8

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These aspects will cause the ore and surrounding rocks weathering, chemical reactivity of Sulphur, especially pyrite and marcasite, forming important accumulations of viscous-fluid material under pressure, generating large risks of exhaust in the tunnel. Another important risk is represented by the 6.3 km length of the tunnel, with a section of 6.3 m2, which has a tendency of crumbling. The crumbled material forms dams that block the tunnel section and underground mining waters accumulate behind them.

When the mud pressure (acid water with heavy metals and suspension) exceeds the limit value of breakage, the dams fails with an explosion effect.

In the last time, there were manifestations of explosive mining water flows - mud from Şuior Baia Sprie tunnel - that concerned authorities, media, locals, etc., which prompted us to carefully consider such issues.

In Baia Mare mining perimeter no surveys have been carried out to estimate and assess the risks related to the water accumulation in underground spaces, the accumulation times, the escape routes and scenarios of the intervention in case of accidents.

In specialized literature, there were approaches to these topics, including solutions to minimize the sulphides reactivity which should have to be adapted to the geo-mining conditions in the area.

2. Opening and operating Șuior ore deposit Șuior ore was classified as a large deposit, with moderate potential value and a relatively small horizontal surface, but with a large extension in depth and very difficult geo- mining and tectonic conditions. These assumptions led to its mixed exploitation.

Fig. 2 Simplified scheme of Șuior ore deposit opening and exploitation The upper part of the deposit, between +1,000 m and +920 m, was exploited in open pit. The area between levels + 920 m and + 850 m was preserved as a safety pillar; while below, the operation was continued in the underground through mining works. (fig. 2, fig. 3 and fig. 4) ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

In fig. 2, fig. 3 and fig. 4 the ore and Șuior mining perimeter geometry and adjacent surface area morphology is presented in a simplified manner.

Fig. 3 presents the initial geometry of Suior ore deposit and the formation of the pit sink and related levels.

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Fig. 3. Vertical profile of Șuior ore deposit

Fig. 4. Situation plan of Șuior ore deposit Fig. 4 presents the situation of Șuior open pit in the moment of closure. Along the underground mining exploitation, using specific methods, this area has been transformed in a crumbling cone. he situation plan allows an estimation of the rain water flow in the operating area.

For underground mining exploitation, a complex opening system was created with two main mining works: - Two ventilation shaft, East and West, on the ore direction, outside its limits; - A vertical blind shaft used to evacuate mining production by gravity to the transport level +462 m;

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Two drifts excavated at the level +800 m, for traffic, ventilation and supply; - The declines, excavated from +800 m, with a rectilinear zone, continued with a spiral route to the base level, used for transport and supply.

As far as the underground ore deposit exploitation is concerned, it was carried out in four stages: - Between levels +850 m and +800 m, two methods were used, with cut and dry filling and shrinkage stopping; - Between levels +800 m and +700 m the method drift and fill was used

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Between levels +700 m and +650 m the deposit was exploited with cut and dry fill and it was created a protection pillow to pass to sublevel stopping exploitation; - Below level +650 m the method with crumbling in sublevel stopping was used.

The particularity of sublevels stopping method consist in drilling finger raised blast holes and blasting, using important explosives charges crumbling the sublevel ore. When the ore is evacuated, the surrounding rocks will fill in the empty space.

As the exploitation level lowers, the crumbling spreads to the surface. This area, together with the open pit, form a subsidence cone which is a way for rainwater to reach in underground drifts, crossing the ore and surrounding rocks, tectonised and cracked, arriving, finally, to the base level +462 m.

Accumulated water has a tendency to flow through the tunnel to Baia Sprie.

3. Geo-mining conditions which favor the phenomena of instability and accumulation of waters Because of the complex geo-mining conditions, ICPMN Baia Mare, the Institute of Mines in Baia Mare, The Mine Institute in Petroșani, ICITPML Craiova carried out numerous studies, published as technical documents in specialized literature [1], [2], [3].

A summary of these studies is presented below in order to highlight the complexity of the conditions subject to the impact on stability over the mine life and the ability of estimation and extrapolation of such phenomena after the mining closure.

The abnormal pressure phenomena recorded in year 1984 at Șuior mine, at the exploitation levels, culminated with a partial closure of many stopes and a substantial preparatory network.

These phenomena have manifested through the convergence of the mining work walls, blisters of hearts, rocks crumbling, and the mining works closure. The concerned manifestations and their scale were due to the petrographic characteristics and geo-mining conditions, both of the surrounding rocks and of vein mineralization.

The country rocks have an advanced degree of deterioration, so that feldspars have undergone major changes through switching to varied species of clay minerals. These minerals easily absorb water which weakens their cohesion, leads to blisters, accelerating rheological phenomena.

Mechanical imbalance is due to the existence in the vein body of an irregular network of cracks and

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fractures filled with kaolin, but also due to the existence of a portion in which the mineralization is in the form of breccia, subject to alteration, too.

The alteration effect is felt both in regards of elasticity static modulus size and the Poisson coefficient, meaning that the values of the first parameter decrease and the values of the second increase, emphasizing the plastic behaviour of andesite occurring with the degree of deterioration.

The ore body and the country rocks are characterized by an advanced fissure which favours water infiltration and reduces the rock stability, showing subsidence trends and enlarging the degree of alteration. The main vein form is amygdaloidal with significant thickness in the central zone and attenuations toward the sidewalls.

In the midline area, thicknesses reach 62 m and, at the ends, the size is reduced to 1.5 m and even less, up to extinction. In areas with large thickness in the ore body appreciable embedded sterile intercalations are shown. They have a lentiform aspect and are made up of pyroxene andesite powerfully transformed by hydrothermal metamorphism. The ore body geometrical characteristics are the following ones: length approximately 650 m; depth of 1200 m; area in the horizontal plane approximately 9000 m2; the dip 85...90o.

Mineralization is composed by: 21 species of sulfides and sulpha-salts: pyrite, marcasite, chalcopyrite, galena, etc; 7 species of nitrogen oxides and hydroxides: limonite, magnetite, hematite, oligist iron, etc; 2 species of sulfates: anglesite and gypsum; 4 species of Cu and Pb carbonates; 11 species of silicates.

At the first level roof, a pyroxene andesite, altered and mineralized was identified. The alteration minerals are kaolin 20%, chlorite, and sericite. Accessory minerals are pyrite (35%), complex sulphurs (blend, galena), and fine granulated pyrite.

First level, vein – pyrite ore cantoned in altered andesite: kaolinite, chlorite and montmorillonite Vein, quartz area Vein, andesitic breccia Vein, quartz and sulfurs: pyrite, sulfurs of Ag and As 2% Pyrite fine granulated First level footwall – marl clay mineralized, pyrite Level IV – vein, complex ore altered andesite; breccia Clay minerals: kaolinite, montmorillonite Pyrite fine granulated or nests in the rock body (20-25%); blende; marcasite; galena 11

Roof – pyroxene andesite altered and unaltered Footwall – marl clay low mineralization, pyrite present Level VII – vein silicified breccia, pyrite 15% in silicic body and sandstones. In footwall, marl clay low mineralized – pyrite and chalcopyrite. (2) Significant presence of clay minerals in vein body and andesite from the roof, marl clay from footwall and important quantities of pyrite and marcasite in all structures (vein, footwall, roof) create all conditions for physical phenomena (inflation, disruption, etc.) and chemical (oxidations) phenomena that lead to the formation of a volume of material with flowing characteristics and important pressure, due to viscosity and density as well as to resulted components of sulphurs oxidation reactions (specially marcasite and pyrite) very toxic for environment.

Kaolinite appears as a feldspar and adularia alteration product and appears frequently as an accumulation of several centimetres in the complex mineralization area. The montmorillonite is present in the vein body as well as in country rocks. The average sulphur content has increasing depth tendency, reaching + 450 m level at 12.6% justifying the apparition of acid waters pH decreasing in some areas at 1,3...2,3.

At superior levels, between +700m ... +900m, in Northern and Southern sides, the vein country rocks are pyroxene andesite strongly sericite, kaolinised and fissured and transformed on large areas in a body with the aspect of clay kaolin.

In the Western area, andesitic rocks, strongly altered towards the central area, appear, with a thin strip of pyroxene andesite of 1...2 m, behind them follows the friable blackish marble and, on the Eastern side, the vein is placed in friable breccia, intensely cracked. In the Southern part, where the developing works are located, including the central shaft, the country rock is pyroxene andesite intensely altered and cracked.

At inferior levels, below 700 m, the vein is in direct contact with the marble from the footwall and below 600 m, the vein is totally cantoned in marble. The marble formations are fissured and, in consequence, crossed and affected by water. Șuior ore deposit is crossed by a major fault called “big central fault” placed in middle area, filled with complex mineralization with thicknesses up to 2 m.

The inflow of mining water. Mining water has the following source: - atmospheric precipitation falling on the open pit surface and surrounding area; - the groundwater table cantoned in the superior zone of altered andesite; - superficial waters, etc.

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The waters’ movement in shall is carried out by natural rock porosity, but especially by weathering fractures and faults of the ore body and the surrounding rocks. The area with more abundant infiltrators is found in the central zone, around the "big central fault". Crossing the mountain, waters acidify, pH 5...1.5, a phenomenon facilitated in the underground by the powerful and specific bacterial flora (thyobacillus ferooxidans) [2].

The intense tectonic degree makes it easy for water to penetrate through marble, which leads to the splitting of large blocks and mudflows.

Studies performed by ICITPML Craiova in 1988 established 5 groups of rocks depending on their deterioration and alterability degree. The first group includes rocks with strong alterability, whose mechanical initial resistance reaches value 0 after 6 years and the second group includes rocks with high alterability, whose very high initial mechanical resistance decrease, after twenty years, to only 1.4...1.8% [3].

4. The estimation of risks generated by water accumulation and mudflow after Șuior perimeter mining closure All geo-mining conditions (mineralogical, petrographic, structural and underground main mining works network) already described create premises to major risks regarding water and mud accumulation.

Geologic conditions increase two important phenomena: rocks weathering and oxidation chemical reactions. The presence, in important quantities, of clay minerals leads to total weathering in short periods of time, in the presence of water. Rocks with high initial mechanical resistance (about hundreds of daN/cm2) get transformed, in relatively short periods of time, in a completely weathered material which, saturated in water, becomes a mudflow with tendency of accumulation in large volumes as mud bags under pressure. The presence in high quantities (tens of %) of marcasite and fine granulated pyrite, extremely reactive minerals, pyrite, arsenious pyrite and other salts lead to oxidation reactions generating acid drainage – acidic water charged in heavy metals and arsenic. As oxidation reactions are exothermic, heat dissipation accelerates these phenomena generating warm groundwater which, during the last explosive discharges, have been recorded due to the elevated temperature and the visible evaporation phenomenon, at the discharges in Săsar River and along it.

Revista Minelor / Mining Revue - no. 3 / 2017

Linked to the geometry of mining perimeter, as well as through the open pit sink transformed subsequently in subsidence cone (fig. 3) and from surrounding slopes (fig. 2) rain water is drained towards underground mining work network.

Underground mining exploitation was developed around 500 m in depth, forming an empty places network resulted after ore exploitation and country rocks crumbling; in this area, water arriving from surface and underground (hydrostatic levels adjacent to mining perimeter) accumulates. In this large space, with significant size, both horizontally and vertically, weathering and oxidation phenomenon happen, forming a mixture of water and fine material called mud.

At the base of this water and mud accumulation and drainage space, the tunnel ȘuiorBaia Sprie, 6.3 Km long, is an escape route (fig. 5).

This tunnel presents the instability phenomenon manifested through rocks crumbling forming digs (stoppers), which occlude partially the water and mud draining until the pressure leads to its breaking through an explosion.

These instability phenomena may occur more strikingly in the future, favoured by the mining waters with acid characteristics, pressure and elevated temperature.

All these explosive mud and mining waters may become most violent, which can no longer be controlled, administered and less cleaned.

Fig. 5. The tunnel route Cavnic-Șuior-Baia Sprie 5. Conclusions The analysis presented in the paper has as a goal the estimation of the major and imminent risks of mining water accumulation in Șuior mining perimeter. These waters generate acid drainage and have an important charge in clay material, weathered, leading to mudflows.

Mining water evacuation (mudflow) occurs at the base level of the mine, through a drift called, symbolically, tunnel, with a long route. All mining waters from the mining perimeter display this evacuation path. Technically, the path has a small section (6,3m2) and poor stability.

ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

Generally, mining closures in Romania ignored almost totally evaluation and prevention of risks generated by water accumulation and evacuation from mining perimeters.

Unlike the other mining perimeters, mining water accumulated in Șuior area becomes, practically, impossible to manage and control, evacuating stormily and unpredictable, impossible to be treated.

The analysis does not claim to be an exhaustive study as it would require more extensive resources and adequate means. Our research approach is just a warning to all those in charge with risk evaluation and management in closed or conserved mining perimeters.

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References 1. Popescu, G. and others Sinteza factorilor geominieri specifici EM Șuior și propuneri privind sistemul de deschidere, pregătire și exploatare a zăcământului sub cota 700 m – studiu 241/1995 Institutul de Subingineri Baia Mare 2. Todorescu, A. Proprietățile rocilor, Editura Tehnică București, 1984 3. Pădure, I., Palamariu, M., Bălănescu, S., Sălăjan, C., Spătar, C. Monografii moderne de exploatare pentru zăcămintele de minereuri, Editura Global Media Image, Deva 2001

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Revista Minelor / Mining Revue - no. 3 / 2017

ANALYSIS OF THE INFLUENCE OF THE MINING ACTIVITIES IN ROVINARI MINING BASIN UPON THE FUNCTIONING OF ROVINARI THERMAL POWER PLANT IN FULLY SAFETY Crina-Adriana DRĂGĂNESCU (GURICĂ)* Abstract: The paper analysed geology, hydrogeology, geomorphology, climate and exploitation activities in the Rovinari mining basin, inside which is located the Rovinari thermal power plant, which the safely function can be affected by these activities.

Key words: Rovinari mining basin, Rovinari thermo power plant, lands features, safety.

1. Introduction Upper mining activities cause, due to their specificity, multiple and varied negative environmental effects, exemplified by: - Changes in relief manifested by landscape degradation and displacements of households and industrial sites in the exploitation areas; - The occupation of large areas of land for exploitation, dumping, storage of useful mineral substances, industrial installations, access roads etc, which are thus totally unusable for other purposes, for a long time, with effects on the local communities (conflicts over land use, displacements, recreation areas, etc.); - Land degradation, vertical and horizontal displacement of the surface and slipping of tailings ponds and tailing ponds, causing serious accidents; - Pollution of surface water and groundwater; - Hydrodynamic imbalance of groundwater; - Negative influences on the atmosphere, flora and fauna in the area; - Chemical soil pollution, which may affect for many years its fertile properties; - Noises, vibrations and radiation spread to the environment, with a strong unfavourable action.

Of these, for the safe operation of a thermal power plant in the area of influence of the activities of open pits, two negative effects are significant, namely an imbalance of hydrodynamic groundwater as a result of the stripping of sterile and extraction of useful coal by the operation area and surface degradation by horizontal and vertical displacements of the surface as a result of dewatering works, displacements that will affect the stability of the buildings inside the power plant and thus endanger completely or partially the technological flux of it.

Today, in Gorj County, the activity of extracting the lignite on the surface is carried out in the open pits: Tismana I, Tismana II, Rovinari East, Gârla, Pinoasa, Roşia de Jiu, North Peșteana, Lupoaia, Roşiuţa I, Jilţ Nord and Jilţ Sud.

* Eng. Ph.D stud – University of Petroșani ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

In the proximity of the above open pits there are two major consumers of extracted lignite i.e.

Rovinari and Turceni thermal power plants.

In the case of Rovinari thermal power plant, at a production level of approx. 8.6TWh/year, lignite consumption at an average calorific value of 1800 kcal/kg (7.6GJ/kg) would be approx. 9.7 million tons, which can be obtained from Pinoasa, Tismana I, Tismana II and Rosia de Jiu open pits (with a total of approximately 500 million tons) for a period of more than 50 years.

For Turceni thermal power plant, taking into account the same levels of electricity production, i.e. 8.6TWh / year, the Jilţ Nord and Jilţ Sud open pits with a total reserve of approx. 270 million tons, can consume consumption for over 30 years.

Exploitation at Gorj County open pits generates the degradation of the aquifer systems intercepted by their site. The aquifer formations by roof and lair of seams of lignite cause difficulties in their exploitation through the danger of inundation of work fronts and mining works, of grounding of the equipment from technological fluxes, or by slipping and dropping the steps and the work and definitive slopes of the open pits. To remove these shortcomings it is necessary to dewater the aquifer formations. Dewatering works in Rovinari open pits, for example, lead to annual discharges of approx. 90 million cubic meters of water from the dewatering bores and pumping stations existing in surface exploitation. Their influence, respectively the dewatering actions on the aquifer system, can be clearly seen on very large distances in the adjacent areas to the open pits. Intense dewatering and evacuation of groundwater can lead to severe and even subdued phenomena, with sudden breaks and landslide of argil-marl formations at the roof of seams coal and horizons of aquifers.

The crushing caused by dewatering and consolidation of the fine-grained aquifer layers produced in the Rovinari thermal power plant area, located in the centre of the Rovinari mining basin, did not exceed 10-15 cm, which did not have any significant negative consequences on this industrial objective.

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The inconveniences generated by the crushing and subsidence phenomena can be avoided if industrial activity is preceded by hydro-geological studies carried out very carefully at a regional level and, on the basis of the results obtained, suitable measures of planning and management of activities are taken.

In this paper we will analyse only the grounds and the exploitation activity of Rovinari thermal power plant that was, is and will be affected by them, based on a geotechnical study of the terrain corresponding to the site of the thermal

power plant, to assess their condition in relation to the loads acting on them and to establish the level of safety of its functioning over a long period.

Depending on the outcome of the evaluation, solutions for improvement and stabilization will also be proposed.

2. Overview of the Rovinari thermal power plant The thermal power plant is located near Rovinari, about 25 km S-V from the Municipality of Tg-Jiu, near the mining exploitation of Rovinari coal basin /2/ (Fig. 1).

Fig. 1. Overview of the Rovinari thermal power plant According to its location, the plant is placed at the "mouth of the mine", unique in Romania, which offers the possibility of direct energy recovery of large quantities of lignite from the corresponding quarries, ensuring also a minimum transportation distance on coal strips from the open pits in Tismana I, Tismana II, Rovinari East, Garla, Pinoasa and Rosia de Jiu. This also involves minimal transport costs of coal, S.E. Rovinari being the only power plant which has no rail transport

Fig. 2. Crushing coal deposit

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costs, the transport of coal being provided on the conveyor belt systems.

If the site of this thermal power plant has the advantages mentioned above, it should not be forgotten a major disadvantage, namely the influence of the activities in open pits that serve it upon the stability of the terrain on which the buildings are located, as well as on the deposits of coal (figures 2 and 3), slag and ash (fig.4).

Fig.3. Coal deposit Central-Pinoasa

Revista Minelor / Mining Revue - no. 3 / 2017

Fig.4. The slag and ash deposit Cicani-Beterega 3. Geology of the area of the Rovinari Thermal Power Plant From a geological point of view, the region falls into the Pre-Carpathian Depression where, at the end of the Cretaceous, there was an immersion of the crystalline foundation, creating a tectonic depression called the Getic Depression, which was crossed by the rivers Olt and Jiu /3/.

The formation of lands of Rovinari occurred in the last part of the Pliocene, from Pontian to Levantin, when slow lifting movements of the marine mixture were recorded, thus determining the development of a marshy region.

These lands impregnated with the abundant vegetation associated with this area led to the creation of the ten coal beds (in the riverside area), over which were deposited marls, fossil clays, sandy clays, sands and gravels entrained by rivers, and above it was laid fertile soil. From a seismic point of view, the administrative area of Rovinari falls within the seismicity zone E (a.g. = 0.12g, T.c. = 1) with a seismic degree 7.

Rovinari Mining Basin is located in the Jiu River meadow, with a hilly relief to the hillside in the west; the lignite deposit is located near the surface and has presented conditions for its exploitation through open pits.

The main mineral and surface mineral resources are: lignite, oil, natural gas, anthracite, graphite, dolomite, granite and chalk.

In the area where the lignite seams of Oltenia are situated, young geological formations are formed, consisting of soft, cohesive and friable rocks (marls, clays, sands, etc.).

The coal layer is caught in clays, marls and sands easy to remove, the exploitation being facilitated by the thickness of the tailings layer not exceeding 2-3 m, the inclination of the lignite ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, PetroĹ&#x;ani, Romania

layers varying between 50 and 100. A drawback is that the coal has relatively small thicknesses, involving large discovery volumes and the retention of a relatively large proportion of tailings in the excavated coal, impacting on its calorific capacity.

Rovinari subsoil had an immense mass of lignite coal, about 200 million tons with an average calorific value of 1945 kcal/kg.

From this total amount, up to the present, 182 million tons (net carbon) were extracted, the difference remaining in the safety pavilions and in the areas occupied by roads, constructions, enclosures, deposits, etc.

The conditions for the exploitation of deposits in the quarries of Oltenia are largely influenced by the physic-mechanical properties of the whole section of the deposit. The values of these characteristics are the basis of the geotechnical calculations for the dimensioning of the open pit geometric elements: step heights, slope angles, width of the beams.

In the conditions of increasing the height of the open pits, the problems of optimization of the basic technological processes (excavation, transport, storage) and of the stability of the slopes become more complex.

The determination of the physical and mechanical characteristics of the deposit cover, the foundations of the waste dumps and the rock mixes to be deposited, is done within each technical documentation, taking into account that under the influence of some factors (water, lithostatic charges, etc.) physical-mechanical rocks change essentially, influencing directly the construction parameters of the heaps.

The rocks in which are located the lignite seams belong to the young formations, Dacian and Quaternary ages. (fig. 5).

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Fig. 5. Stratigraphy of the Rovinari coal basin and the physico-mechanical characteristics of the rocks The stratigraphy of the deposit is composed by argillaceous rocks of Dacian age over which alluvial quaternary deposits are settled.

Dacian deposits are mostly formed of argillaceous rocks and powdery clays. Intersections of powdery sands and sandy powder of the marlargil complex located in the roof of lignite V layer, contain underground water under pressure.

Alluvial quaternary deposits consist of:  Pelitic rocks (vegetal soil, sandy clays, argillaceous sands, argillaceous powders);  Psamito-psephitized rocks (gravel and boulders).

The quaternary pelitic rocks are settled in the upper part of the flat, having a height of 0-2 m, rarely reaching 4 m.

From the particle size point of view, quaternary pelitic rocks are very varied: - sandy clays pass easily into argillaceous sands.

- argillaceous sands pass easily into argillaceous sandy powders.

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The quaternary psamito-psephitic rocks are settled in the lower part of the floor, with their height of 5-7 m and 10 m in certain areas.

Although almost entirely saturated with water, due to the high values of the filtering coefficients and the yield capacity, these rocks do not pose any particular problems with the dewatering.

Based on the analysis of particle size, plasticity index and cohesion, it highlights the following categories of rocks:  non-cohesive: sands and gravel;  poorly cohesive: sandy or dusty clays and argillaceous or sandy powders;  cohesive: clays and marl.

4. The energy resource of the Rovinari coal basin With all the factors favouring the formation of lignite deposits, during the clogging of the Getic Basin, a charcoal complex consisting of 21 lignite seams was settled, alternating with pelitic and psamatic deposits.

Revista Minelor / Mining Revue - no. 3 / 2017

Lenticular lenses and low height lignite seams I-III are inexhaustible.

Coal seam IV, arranged in the roof of the horizon of artesian aquifer, consists of 1-3 coal benches with average height of 0.3 - 1.9 m. The interval between layers III and IV consists of medium grain sand.

Coal seam V reaches height of over 7 m and branches into two benches across the entire surface of the basin. In Pesteana Sud, North Pestera, Urdari and Rosia Jiu open pits the coal seam V is located under heavy hydrogeological conditions.

Coal seam VI has a uniform development with height of 0.7 - 4.5 m in the perimeters where it appears singular (Pinoasa, Roşia de Jiu, Tismana) and 4.0 - 6.5m in the areas where it appears united with the layer VII. Coal seam VII consists of 1-5 coal benches with height of 0.5 - 5.6 m (at Roşia de Jiu), 0.8-3.8 m (in the Gârla open pit), 1.8-4.3 m (at the Rovinari Est open pit) and 0.4 - 3.6 m (at Peșteana Nord).

Coal seam VIII develops unitary or fasciculate in several benches, two of which have exploitable height, separated by a layer of argil not exceeding 1 - 5 m. The height of the upper layer VIII is 2.0 - 3.5 m and the lower layer of 0.5 - 1.2 m.

Coal seam IX has extensive erosion or nonsedimentation areas. It consists of 1-5 coal benches with a total average height of between 0.5 - 2.7 m.

Coal seam X is one of the most important exploitable layers, but has extensive erosion areas.

It is a fasciculate layer, developing on two levels:

the lower layer X, with height of 0.5 - 2.4 m; the top layer X, with a height of 4.0 m, the maximum height being 7 m.

Coal seam XI consists of 1-4 junctions with height between 0.2 - 2.0 m. This coal seam has erosion surfaces in the high areas of the interfluves valleys.

Coal seam XII is developed in the hilly area of the basin with a height of 1.6 - 1.7 m.

Coal seams XIII, XIV and XV have low heights and extensions, appearing only in hilly areas.

5. Climate conditions of the area Rovinari mining area, it is included in the climate of hills and plateaus, with a continental climate, as a result of the transition from alpine climate of the Carpathians Mountains and the plain of Oltenia. The temperature of the air, as a multiannual average, is around 10oC. Summers are moderate and winters are mild with sufficient precipitations, but unevenly distributed: abundant in spring, autumn and winter and summer deficient.

Between November and March, the activity of the open pits work in difficult or heavy conditions.

Due to the relief configuration, the climate is differentiated according to the relief steps. Annual average temperatures rise from north to south. The dominant winds are the Nordic. The prevailing wind direction is northwest, its average speed being 3.2 m / s (fig.6).

Fig.6. Wind rose in Rovinari ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

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Due to the shelter in the depressions, the average thermal values rise to 9-10°C. The precipitation decreases with the altitude, from 1400 mm on the mountain peaks to 600-700 mm in the Oltenia Sub-Carpathians and 600-500 mm in the Getic Plateau.

The S-V position of the territory includes it in the area of manifestation of the sub-Mediterranean influences, especially felt in the western depressions (Turnu Severin, Tismana, Baia de Aramă). Also in V-N-V there are phenomena of weaker intensity.

It is a slight mood of climatic desertification in the west-east and north-south directions, the southeastern corner of the region having the most prominent rigor /1/.

The main features of the climate are:  Average annual temperature + 11°C  Maximum temperature + 45°C (summer)  Minimum temperature - 30°C (winter)  Days with precipitation - about 90 days/year The temperature at the surface of the soil is differentiated, with annual averages decreasing with the increase in altitude.

From one place to another, depending on the structure of the active surface, soil temperature values may have substantial changes. They can grow at 1-20°C on sunny and sheltered surfaces, but may fall in forested areas, wetted areas of valleys, or in heavily ventilated areas (meadows and open pits).

The winter thermal regime is characterized by negative thermal values, which are a necessary condition for the production of specific phenomena.

The multi-annual average of frost-days is 110-120 days/year, with an average of 28.7 days in January, with a frost.

The average date of the first frost is from 15 to 20 October, and the average frost is 15-25 April.

The relative humidity of the air in the analysed area averages 68-70% per year, increasing to forested areas on the sides of the hills and to the

Hydrometric station Average precipitation (mm)

Tabel 1. Average precipitations recorded at the Rovinari hydrometric station I II III IV V VI VII VIII IX X XI

XII

39,9

57,6

21,9

17,7

68,4

66,2

6. Vegetation and fauna of the area The flora and fauna of the area are varied. The flora consists of over 2000 species of subMediterranean, Pontic, Balkan and Balkan-Dacic plants /1/.

The perimeter analysed is floral in the vegetation area of the deciduous forests.

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riverside of river Jiu at over 75%. Relative maximum moisture is recorded in December and January, 82-85%, and the lowest in July and August by 62-63%.

As a result of the multiannual general trend of multiannual average temperature increase, there has been a certain tendency of decreasing moisture lately.

Due to the scale of the anthropogenic activities in the analysed area (mining and electricity production in thermal power plants), the nebulosity is higher compared to the neighboring regions, the multiannual average in the area being about 5.5-5.8 tens and the annual amplitude of about 3.3 tenths.

The highest values of nebulosity are recorded from November to March, exceeding 6.8 - 6.9 tenths, and the lowest from July to September, with values below 3.5 tenths.

From the analysis of observations regarding the atmospheric precipitation in the last ten years, at the hydrometric station in Rovinari, the following monthly averages (Table 1) are observed: - the average multiannual of precipitations is 644.6 mm.

- the maximum of precipitations in one year is recorded in July and September by 81-90 mm; the minimum is recorded in March by 18 mm; - the maximum of precipitations in 24 hours was 89 - 95 mm; - the average number of snow days is 25-40 days / year the snow cover period is 40-70 days/year.

The average annual evaporation-transpiration for the studied area is approximately 669 mm, and the average annual evaporation of 571 mm, the maxims being recorded in July, by more than 122 mm.

The surplus of water in the soil, compared to the evaporation potential, reaches 182 mm, the maximum being recorded in January, by 53 mm.

The water deficit in the soil relative to the evaporation potential is 98 mm, the maximum being recorded in August by 69 mm.

66,0

81,2

55,2

90,4

52,3

27,8

The bio-geographical potential is arranged in close correlation with the morphological factors. Its most expressive element, vegetation, describe its associations without symmetry, starting with the thermophilic oak forests in the low hills of the Getic Plateau and continuing with the hills of 450600 m, with the holm-beech forests of a transition Revista Minelor / Mining Revue - no. 3 / 2017

placed at 600-700 m, and beech developed floor-up to 1100 m.

A characteristic of the vegetation of the region is the intercalation, in the lower floors, of subMediterranean species such as the flowering ash, hornbeams, the lilac, and hawthorn.

While the spontaneous vegetation is represented by the bull thistle (Cyrsium arvense), the shepherd's purse (Capsella bursa pastoris), wheat grass (Agropyrum repens), the crop species are represented by wheat, corn, potatoes, fruit trees, vine.

A similar arrangement is displayed by the fauna elements, in the woods which are the favourite biotope for the wild boar, wolf, fox, wild cat, beetle, finches, and in the coniferous bears, deer, laughter, jar, eagles. Hotter climate elements such as corn viper (on the sunny limestone of Motru to Mehedinti) also appear.

The soil cover preserves in its typology the influences of the lithological substrate, climate or vegetation. On the limestone of sub-Carpathians, of Getic Plateau, there were rendzine and pseudorendzins, under the beech forests reddish, brown reddish or brown soils, under the coniferous intensely acidified podzola. Hydro-morphic, alluvial, or regosolar soils are not missing.

The mining works carried out in the area led to the clearance of hundreds of hectares, which resulted the destruction of the natural flora and the strong

influence of the neighbouring areas. The consequence of this situation is the marked reduction of the floral diversity in the analyzed territory. The restoration of the vegetation is observed on the fields on the heaps where, from the first year after deposition, the spontaneous flora appears. A feature of planting vegetation on tailings dumps is the mass appearance of the Phytollacca americana species. In the process of restoration of the vegetation, Salsola ruthenica (cocklebur), a species known especially in the Romanian Plain, appears quite frequently on the heaps. On the slopes of the steep slopes, caused by the mining works, Cirsium candelabrum, another interesting species for this area, is planted.

7. The operating perimeters adjacent to the Rovinari Thermal Power Plant (fig. 7) The deposit conditions in the exploitation perimeters are specific to the structure of the geological formations in the region, being defined by the way of presentation of the lignite layers, their thickness, the lithological nature of the rocks, the structural configuration, and the hydrogeological conditions. These factors must be carefully studied in the technical documentation drawn up at the level of the mining units, the results underlying the calculations of the stability of the pit pitches and the determination of the production capacities /4/.

Fig.7. Mining basin Rovinari - perimeters adjacent to the Thermal Power Plant ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, PetroĹ&#x;ani, Romania

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In all cases where the geomorphology of the perimeter (the transition from the meadow to the hill area) has changed, there have been changes in the conditions of the deposit regarding: - geotechnical characteristics; - position, thickness and tilt of the strata; - hydrogeological conditions; - the lithological structure of the steps, etc.

In the Jiu hydrographic basin siliceous rocks predominate, the limestone being on small surfaces at the upper part of the mountainous area as well as in the northern part of the sub-basins Bahna and Topolnita.

The ratio to be found in the meadow area is 5.2 m3/t, and in the hilly area of 6.05 m3/t.

At the beginning of 1970, the basin was outlined with approved technical and economical studies and the open pits Beterega, Gârla, Tismana, Cicani were in operation or opened and since 1973, Roşia de Jiu. In order to cover the coal demand for the thermal power stations in the area (Rovinari and Turceni), four further perimeters were in operation for open pits: Rovinari Est, Peşteana-Urdari and Pinoasa.

Tismana open pit. In order to increase production capacity in this quarry and to eliminate the deficiency of excavation and dump capacity at the level of 1975, the study elaborated for the period 1976-1980 foresaw the introduction of a new technological line consisting of a wheel excavator and an abzeter with the help of to which the production capacity of the open pit could be increased to 4000 thousand tons since 1978.

Rovinari Est open pit. The reserve is cantonated in this perimeter in the V, VI, VII, and VIII levels. Although it has the opening trench in the meadow area (from the opening trench, the Beterega open pit in the counter front), it will enter the hill area between 180 and 350 m.

The perimeter of the open pit is affected by the Bălăceşti-Cîrbeşti fault and the faults of Dâmbă, Corbului and Moi, which gives this perimeter a rather complicated tectonics, which has the effect of complicating the technological flow of exploitation in the open pit. The V-VIII coal seams totals an average exploitation depth of this 12.2 m pitcher.

Pinoasa open pit. The perimeter affected by this quarry is entirely hilly and has been designed according to previous provisions for underground exploitation (the abandoned Pinoasa mine).

The exploitable coal seams are: X with a thickness of 1.5-5 m (with two or more jambs), XI by 1.0-2.5 m, by IX by 1-1.5 m, by VII by 2-4 m , VI of 2.5-3.2 m, V of 1.5-3 m. There is also a sporadic layer XII with a thickness of 1 m.

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The distance between the latitudes is between 6 and 20 m. In the roof and the bed of the coal seams there is an alternation of fine clays and sands, as well as aquifers or lenticular horizons with low pressure. In the bed of the IV layer, there is the artesian aquifer horizon. Career hearth is on coal seam V. The industrial reserve calculated over a period of 20 years is 63,500 thousand tons with a total area of 1.059 ha, the average discovery ratio is 6.01 m3/t. The total volume of the dump is 661 mil m3, out of which 355 mil m3 in the over heap Gârla and Tismana. The works of this open pit began in 1983 with classic machines in small open pits, opening Pinoasa I, II and II. Later, Pinoasa IV and V were opened. The opening transection for the Pinoasa II and V open pit separated by the Rogojel valley was designed to unite the north-eastern zone of the quarry. By joining the two opening, southern and northeast open trenches, the opening trench for the entire Pinoasa mining field will be formed.

The perimeter of the open pit being near the ponds North and South Pesteana, the surface arrangements were foreseen in common with these quarries by extending the constructions from the assembly platform, the coal deposit and the enclosure.

The opening trench was located on the eastern side of the perimeter. The outer dump, in a volume of 15 million m3, was placed between the open pits of Pesteana Nord and Pesteana Sud. The exploitable seam is X and consists of 4-5 junctions with a thickness between 5 and 10 m. In the roof and the bed of X seam, there is an alternation of clay and sand. In the couch are aqueducts horizons with elevation.

Roşia de Jiu open pit. Its perimeter is located on the right bank of the Jiu River, south of the city of Rovinari. The entire career field includes: • the riverside area located on the right bank of the Jiu river, in the vicinity of the Moi and Vlăduleni localities, on the north side and respectively on the Fărcăşeşti and Roşia-Jiu localities on the southern side; • the hilly area south of the village of Roşia-Jiu, bounded between Valea Pârâului and Valea Roşie.

The riverside of Jiu is about 2 km wide and has odds of +148 m to +160 m, with inclinations east, Jiu and south. In the hilly area the hills are ENE-VSV oriented and have heights between the 1.70 m and 300 m elevations In this area, erosion has removed coal seams XIII-XVII, and in the meadow zones the seams XIXVII. Lower carbon strata have small tilts (2-30), while upper layers have slightly more pronounced tilts (4-100).

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Within the Roşia de Jiu perimeter, in the Dacian, Romanian and Quaternary formations were highlighted sandy levels with varying thicknesses and granulometry, alternating with clay, marl and coal deposits. Within these porous-permeable formations, aquifers are individualized which, depending on the conditions of the deposit, are free or deep under pressure.

8. Conclusions The paper has intended to be an introduction to a broader study on the influence of the mining lignite quarries in the Rovinari mining basin dealing with the stability of the buildings in the Rovinari thermal power plant and its coal and slagash deposits. This stability depends on the safe functioning of the thermal power plant throughout its lifetime.

Knowledge of the geology of the site, the geological and mining characteristics of the rocks, the hydrogeology, the climate and the exploitation technologies will allow for a correct analysis of the stability of the foundation grounds of the buildings inside of the energy complex and finding suitable solutions for the remediation of potential accidents.

References 1. Cornescu (Pecingină) Irina-Ramona Cercetări asupra refacerii mediului acvatic afectat de activitățile miniere din zona Rovinari, aferent bazinului hidrografic mijlociu al Jiului, teză de doctorat Universitatea din Petroșani, 2013.

2. Drăgănescu (Gurică) Crina-Adriana Analiza situației actuale și viitoare a sectorului energetic din județul Gorj – Raport de cercetare științifică nr.1 Universitatea din Petroșani.

3. Drăgănescu (Gurică) Crina-Adriana Studiul geotehnic şi al regimului hidrodinamic al terenurilor pe care sunt amplasate CET-urile din județul Gorj – Raport de cercetare științifică nr.2 , Universitatea din Petroșani.

4. Fodor, D. Lignitul – importantă resursă a României – Lucrările celei de-a III-a Conferință Națională a Academiei de Științe Tehnice din România, Cluj-Napoca, 12-13 noiembrie 2008.

5. Huidu E., Scorţariu O.V., Ghioc, Şt.

Despre minerit Oltenia, martie 2016, pentru Complexul Energetic Oltenia - Tg-Jiu. 6. Rotunjanu, I., Lazăr M. Hidrologie și hidrogeologie minieră. Ed. Universitas, Petroșani, 2014.

7. Trotea, T. Cărbunele din Oltenia o soluție sigură a energeticii românești –2016.

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RESEARCH REGARDING THE STABILITY OF A1 MOTORWAY IN THE LUGOJ-DEVA SECTION, LOT 2 KM: 27+620÷47+090 Ileana PASCU* Abstract: This paper is part of a larger study and lays the foundation of my doctoral thesis. It presents the research carried out on the area where the motorway section will be founded and on the grounds included in the construction of this motorway. In order to determine the stability of the motorway, many laboratory tests had to be carried out, which then allowed to perform the stability calculations. All the results are based on modern methods of analysis and calculation that have been correlated with the standards required for such studies.

Cuvinte cheie: motorway, geo-mechanical features, base land, grounds, stability 1. Introduction The Deva-Lugoj motorway section is part of the A1 Motorway: Bucharest - Piteşti - Curtea de Argeş - Sibiu - Deva - Timişoara - Arad - Nădlac.

At present, it is partially carried out (Bucharest - Pitesti - 100%, Piteşti - Sibiu - in the process of bidding, Deva - Timişoara - partially carried out, Arad - Nădlac – entirely carried out).

The Romanian National Road Infrastructure Company, following the public tender procedures, has designated the Design and Execution of the Lot2 Motorway, km 27+620 - km 56+220, to an

international concern, based on technical and economic criteria.

The length of the studied section represents 19.47 km, containing earthworks, art works, hydrological works of riverbed improvement, water collection and drainage, etc. For a good collaboration and execution control, the length was divided into the following sectors: A (km 27+620 ÷ km 32+330); B (km 32+330 ÷ km 37+681); C (km 37+681 ÷ km 42+695) and D (km 42+695 ÷ km 47+090) (fig.1).

Fig. 1. Route of Lugoj-Deva motorway section, Lot 2 2. General characteristics of the analysed section The route of Deva – Lugoj motorway, Lot 2 crosses Becheiului Plain on the territory of Timiș County and Fragului Hills at the border between Timiș and Hunedoara counties and passes through the administrative territories of the following inhabited areas: Traian Vuia, Dumbrava, Făget, Margina (Nemeşti, Zorani), Costeiul de Sus and Coșevița. ___________________________________ * Ph.D stud.eng. University of Petroșani

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On a horizontal plane, the route has the following features: - The classification according to technical class I (in accordance to the Technical Norms regarding the establishment of the technical road class, approved

by Order no. 46/1998 issued by the Ministry of Transport); - The design speed for a class I technical road in the lowland area is 120 km/h and in the hill area is 100 km/h; - The connection radii range from 720 m to 17,000m, which ensures the design speed of 120 km/h.

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On a vertical plan, the route has the next features: - The connection radii are in accordance with the normative PD 162-2002 Normative on the design of extra-urban motorways and TEM rules for motorways, ensuring a design speed of 120 km/h; - On the whole route, the situation of declivities is as follows: (0-1) ‰ (87.06%) and (1-3) ‰ (12.94%).

Throughout the whole route analysed, there are flooded and marshy areas, where, during rainy seasons, floods can affect large areas on the surface, due to the low permeability of surface horizons.

Along the route, in all the sectors covered by this study, several types of works are executed, such as earthworks (excavations and embankments), art works (culverts, boxed structures, passages and bridges) and hydro-technical works (corrections and recalibrations of watercourses, consolidations and protections of the watercourses’ banks, the creation of a protection for the gabions placed at the base of the abutments of the bridges over the water courses, and discharge works – collection of meteoric waters: open collector channels, gutters, discharge channels, drainage channels, catch pits with mineral oil separators and petroleum products and a tank).

The road structure considered has been dimensioned and verified under the freeze-thaw phenomenon, according to STAS 1709/1 and STAS 1709/2.

At present, the studied motorway section is executed in a proportion of 95%.

3. The geo-mechanical characteristics of the base terrain and of the soils used for the motorway construction 3.1. Geo-mechanical characteristics of the base terrain In the present study, both field and laboratory geotechnical investigations have been carried out.

3.1.1. Geotechnical field investigations  In sector A, there were executed: - 18 drillings with depths between 6.00m and 25.00m, - 2 dynamic cone penetrations made with super heavy dynamic penetrometer (DPSH -Type B) - 4 dynamic cone penetrations made with light dynamic penetrometer (PDU) - for alignment, 5 drillings (FA01 - FA05) with depths between 10.00 – 15.00 m - for structures 3 drillings (FS01 - FS03) with depths between 15.00 – 20.0 m  In sector B, there were executed: - 15 drillings with depths between 6.00m and 25.00m - 8 dynamic cone penetrations made with super heavy dynamic penetrometer (DPSH - Type B) ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

- for alignment: 6 drillings (FA06 - FA11) with depths between 10.00 – 20.00 m - for structures: 3 drillings (FS04 - FS06) with depths of 20.00 m and, respectively, 35.00 m  In sector C, there were executed: - 21 drillings with depths between 6.00m and 25.00m - 5 dynamic cone penetrations made with super heavy dynamic penetrometer (DPSH -Type B) - for alignment: 5 drillings (FA12 - FA16) with depths between 10.00 – 20.00 m - for structures: 6 drillings (FS07 - FS12) with depths of 15.00 m and 35.00 m, respectively  In sector D, there were executed: - 23 drillings with depths between 6.00m and 25.00m - 4 dynamic cone penetrations with super heavy dynamic penetrometer (DPSH-Type B) - for alignment: 8 drillings (FA17 - FA24) with depths between 10.00 - 20.00 m - for structures: 8 drillings (FS04 - FS06) with depths between 10.00 – 35.00 m Continuous samples have been taken from the drillings, alternately from 2 to 2 meters and/or at the change of layer, undisturbed soil samples and cores that were analysed in the laboratory according to the standards in force. If a water infiltration or hydrostatic level has been encountered during the drilling, this has been mentioned in the drilling report.

3.1.2. Laboratory tests Laboratory analyses were carried out in accordance with the standards in force on disturbed (T), undisturbed (N) and core (C) samples. The laboratory analyses performed consisted in determining the following geo-mechanical characteristics: natural humidity, natural density, plasticity limit and consistency index, granulometric distribution, compressibility and consolidation in endometer, in natural and flooded samples, shear resistance by direct shear (CU, CD), uniaxial compression, free swelling, humus content, carbonate content, aggressive water analysis on concrete and metals.

3.1.3. Interpretation of results Based on the results of the laboratory analyses and geotechnical investigations, the stratification encountered along Lugoj - Deva motorway, Lot 2 can be divided into horizons with similar physicomechanical properties. The stratification was divided (lithological profile) as:  Sector A:  Covering Formations: Alluvial deposits A1 horizon - consisting of cohesive soils: clays, dusty clays and dusty sandy clays.

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A2 horizon - consisting of poorly cohesive soils: sandy dusts, sandy clayey dusts, clayey sands and dusty sands.

Diluvia / eluvia deposits B1 horizon - consisting of cohesive soils: fat clays, clays, dusty clays and sandy clays.

B3 horizon - consisting of non-cohesive soils: gravels with sands, dusty sands with gravels, clayey sands with gravels.  Base Formations : C1 horizon - composed of cohesive soils: fat clays, clays and dusty clays with loamy appearance.

C2 horizon - composed of poorly cohesive soils: sandy dusts, dusty sands and rarely clayey dusts and sands.  Sector B:  Covering Formations: Alluvial deposits A1 horizon - consisting of cohesive soils: fat clays, clays and dusty clays.

A2 horizon - consisting of poorly cohesive soils: sandy dusts, clayey dusts, dusts and dusty sands.

A3 horizon – consisting of non-cohesive soils: gravels and boulders with sandy dusts.

Diluvia / eluvia deposits B1 horizon - consisting of cohesive soils: fat clays, clays, dusty clays and sandy clays.

B2 horizon - consisting up of poorly cohesive soils: sandy dusts, clayey sandy dusts, clayey dusts, dusty sands and clayey sands.

B3 horizon - consisting of non-cohesive soils: sands, gravels with sands, gravels with sands or dusty sands or clayey sands, dusty sands with gravels.  Base Formations: C1 horizon - composed of cohesive soils: fat clays, clays, dusty clays and sandy clays.

C2 horizon - composed of poorly cohesive soils: sandy dusts and dusty sands.

C3 horizon - is composed by non-cohesive soils: sands.  Sector C:  Covering Formations: Alluvial deposits A1 horizon - consisting of cohesive soils: fat clays, clays and dusty clays.

A2 horizon - consisting of poorly cohesive soils: clayey dusts, sandy clayey dusts, sandy dusts, dusty sands and clayey sands.

A3 horizon – consisting of non-cohesive soils: sands, sands with gravels, gravels with sands, gravels with dusty sands.

Diluvia / eluvia deposits B1 horizon - consisting of cohesive soils: fat clays, clays, dusty clays and rarely sandy clays.

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B2 horizon - consisting up of poorly cohesive soils: sandy dusts, clayey sands and dusty sands.

B3 horizon - consisting of non-cohesive soils: sands, sands with gravels, gravels with sands and gravels with dusty sands.  Base Formations: C1 horizon - composed of cohesive soils: fat clays, clays, dusty clays.

C2 horizon - composed of poorly cohesive soils: clayey dusts, sandy dusts and dusty sands.

C3 horizon - is composed by non-cohesive soils: sands.

C4 horizon - is composed by loamy cohesive soils: fat clays, clays, dusty clays.  Sector D:  Covering Formations: Alluvial deposits A1 horizon - consisting of cohesive soils: fat clays, clays, dusty clays and sandy clays.

A2 horizon - consisting of poorly cohesive soils: clayey dusts, sandy clayey dusts, sandy dusts, dusty sands and clayey sands.

A3 horizon – consisting of non-cohesive soils: sands, sands with gravels, gravels with sands, dusty sands with small gravels, gravels with dusty sand.

Diluvia / eluvia deposits B1 horizon - consisting of cohesive soils: fat clays, clays, dusty clays and sandy clays.

B2 horizon - consisting of poorly cohesive soils: sandy dusts, clayey dusts, dusty sands and clayey sands and dust.

B3 horizon - consisting of non-cohesive soils: sands, gravels with sands and boulders.  Base Formations: C1 horizon - composed of cohesive soils: fat clays and clays.

C2 horizon - composed of poorly cohesive soils: sandy dusts, clayey sandy dusts, clayey dusts and dusty sands.

C3 horizon - is composed by non-cohesive soils: sands.

C4 horizon - is composed by loamy cohesive soils: fat clays, clays and dusty clays.

3.2. Geo-mechanical characteristics of the soils used in the construction The construction of the motorway was made from local materials. The execution of an embankment involves the fulfilment of some technical conditions that take into account: the shape, size and ultimate deviation, the research of the material that is part of the embankments materialized by laboratory studies for the determination of their physical and mechanical characteristics, the establishment of the categories and types of terrains used in the execution of embankments.

Revista Minelor / Mining Revue - no. 3 / 2017

In Romania, the soils used for embankment is classified into five groups (STAS 2914-88), namely coarse non-cohesive soils, medium and fine noncohesive soils and cohesive soils.

As filling material of the embankments’ body, it was used the material from the excavations required on the motorway’s route. The material resulting from the excavations was classified mainly as cohesive material. As a consequence of the results obtained by the laboratory analysis (analysis of the physical-mechanical characteristics, freeze-thaw verification, internal friction angle, cohesion, etc.), they could be used for filling in the body of the motorway, meeting the normative requirements in force.

The geotechnical computation features adopted for the clayey materials for embankments are: - Internal friction angle  = 12° - Cohesion c = 25 kPa - Volumetric weight ɣ = 20 kN/m3 To complete the filling works, it was also necessary to provide material from borrow pits, appropriate local material.

For each type of material used in the body of the motorway, experimental polygons were executed.

The embankment of the motorway’s body was executed in layers. In order to ensure a further safety of the stability of the embankments, the physical mechanical characteristics of some layers were improved by treating them with hydraulic binders.

Embankments’ execution was realized in extra profile in order to achieve well compacted slopes, obtained by excavation with an inclination of 1: 1.5 (H/L).

4. Stability analysis 4.1. Establishment of calculation elements These calculation elements aim at establishing the stability conditions (safety factors) for embankments and excavations and at determining the maximum value of embankments’ consolidation (at the level of the road system and at the level of the base, at axis).

The calculation of the embankment structures involved the following steps: - establishing the calculation values for geotechnical parameters based on the existing data, values resulting either from a statistical calculation of data grouped on homogeneous layers where the volume of information allowed this analysis, or by extrapolating data from similar sections filtered through the lens of the values recommended by standards; - simplifying the lithology where the variations of the physical mechanical parameters were reduced and obtaining a simpler calculation in the end;

ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

- analysing the stability using the plan of deformation model in the hypothesis of a perfectly plastic behaviour of the material, using the MohrCoulomb failure criterion; - calculating the deformability of embankments by considering rheological phenomena.

The selection of the calculation profiles was done according to the geometry of the structures (the embankments and excavations with the highest height were chosen), to the land characteristics and the ground water level.

The basic data were the layers’ description, the drilling reports, the in-situ and laboratory analyses, the monitoring of the piezometric level.

The values of the parameters in the embankments’ analysis were taken as averages of the characteristics of the soils resulting from the excavations, but also taking into account their improvement due to compaction: γ = 20kN/m3; E = 24000kPa; ν = 0.35; k = 15º; ck = 35kPa; k = 1 x 10 –7 cm/s.

In the embankments’ stability analyses, for the parameters of the resistance to shear stress of the layers from natural land, the minimum values of laboratory results, Xkinf, determined on the regulation NP 122:2010, were used as characteristic values 4.2. Stability analysis The method underlying the embankments’ stability analysis is the Bishop limit equilibrium method. The calculation is automatic, using the SLOPE/W program - version 2007.

The stability analysis takes into account both the potential slip surfaces of circular shape and those of polygonal shape.

For each type of geometry of potential slip surfaces, after determining the surface with the lowest stability factor, the program runs a procedure to optimize it. Finally, a composite geometry surface can result, corresponding to the minimum stability factor, in cases when, in the natural land, there are layers with significant variations in shear stress resistance.

In order to define the potential slip surfaces of circular shape, a network of slip surfaces centres and a set of lines tangent to these are used, fig. 2.

grid of centres set of tangency lines

Fig. 2. Choosing the potential slip surfaces 27

There may be defined local slip surfaces for a part of the embankment or general slip surfaces for the entire cross-sectional profile studied, taking into account the presence of base rock or of some layers with poor mechanical characteristics that may influence the position of the critical slip surface.

To determine the critical slip surface (for which the safety factor to stability is minimal), all possible combinations of centres of slip surfaces and the lines tangential to them are analysed. The results are presented in the form of equal safety factor curves, the minimum safety factor corresponding to the critical slip surface being highlighted.

If the minimum safety factor value corresponds to a centre that is at the edge of the centre network, figure 3, this network will be extended until the minimum safety factor position is framed by higher safety factor curves, figure 4.

1.664

Fig.3. Incorrectly positioned center network

1.628

Fig.4. Correctly positioned center network Polygonal surfaces are defined in the program with the help of two grids (networks). The line segment joining one point of the two grids forms the basis of the potential slip surfaces. The other two line segments, which form the edges of the surfaces, vary as inclination with an established step, having one end in the point network and the other at the intersection with the land line. In this way, polygonal surfaces are formed by three line segments. The potential slip surface, with the minimum stability factor, is correctly chosen when the ends of the middle segment (base of the surface) are not on the outline of the two points network (figs. 5 and 6).

At the end, the program has the option of optimizing the polygonal surface with the lowest stability factor, resulting in a composite geometry surface.

Fig. 5. Incorrectly positioned point network

Fig.6. Correctly positioned point network 28

Revista Minelor / Mining Revue - no. 3 / 2017

According to the provisions of the national annex to SR EN 1997-1/2004, in the static analysis, the calculation approaches in Romania are Approach 1 and Approach 3, which are essential for the way in which the values for the calculation of actions, resistances and parameters resistance of the materials and partial coefficients will be chosen and used.

Thus, the calculation Approach 1 allows the use of two groups and sets of partial coefficients to verify that it is not reached in any limit status (GEO and STR): excessive yield or deformation.

Grouping 1: A1 + M1 + R1 Grouping 2: A2 + M2 + R1 In this case, the partial coefficients apply to the actions and parameters of the resistance of the land.

Grouping 1 is generally more severe in terms of the structural dimensioning of works in contact with land, while grouping 2 is more severe in terms of geotechnical characteristics. It turns out that grouping 2 (A2 + M2 + R1) is more unfavorable for the verification of the slopes’ stability.

In the calculation Approach 3, according to NOTE 2 of SREN 1997-1: 2004, in the case of calculating slope stability or general stability, the actions applied to the land (e.g. structure, traffic) are treated as geotechnical actions, so that grouping sets of partial coefficients is: A2 + M2 + R3 In this approach, the partial coefficients are applied to the geotechnical actions and to the resistance parameters of the land.

Based on the values of the partial coefficients corresponding to the two calculation Approaches (1 and 3) and the corresponding sets in Tables A3, A4 and A14 of SREN 1997-1: 2004, it is observed that in the case of slopes’ stability and general stability, Approach 1 - grouping 2 becomes identical to calculation Approach 3.

That is why, for problems regarding slopes’ stability and general stability, the most unfavorable for the static analysis is Approach 1 - grouping 2.

In the dynamic analysis, the partial coefficients for actions or actions’ effects in the earthquake calculation are equal to the unit, according to SR EN1990 NA: 2006, section A1.3.2 and table NA A1.3.

Partial coefficients for earth parameters are specified in SR EN 1998-5/NA: 2007, at 3.1. It is noted that they are equal in value to those corresponding to the M2 set in SR EN 1997-1: 2004, as follows: - according to Table A.4 in SR EN 1997-1, the values of partial safety coefficients for earth parameters (ɣM) - set M2 are: ɣØ = 1.25 for the internal friction angle (applied to tgØ) ɣcu = 1.4 for the not drained cohesion

ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

- for the earthquake calculation, the national annex SR EN 1998-5/NA specifies in the note in point 3.1 the recommended values on the territory of Romania for the partial safety coefficients of the shear stress resistance parameters: ɣØ = 1.25 for the internal friction angle (applied to tgØ) ɣcu = 1.4 for not drained cohesion Stability analyses were performed in dynamic conditions (earthquake with ag = 0.12 g). The dynamic analysis is performed with the method of static equivalent forces, in the sense of considering a horizontal inertial force equivalent to the seismic demand.

According to section 2.4.7.3.1 of the SR EN 1997-1: 2004, for the land yield limit state (GEO), it is necessary to verify the fulfilment of the condition: Ed ≤ Rd, where: Ed is the value of the action effect calculation (in our case, the mobilized shear stress resistance) and Rd is the value of the resistance calculation (represented by the shear stress strength available), which results to an admissible stability factor Fsadmissible = 1.00.

The verification condition being Fseffective ≥ admissibile Fs (condition which, if fulfilled in the earthquake analysis, is also fulfilled in the static analysis, because in the dynamic analysis, horizontal inertial forces with a destabilizing role also intervene, and the values of the partial safety coefficients of the earth parameters are the same (those corresponding to the M2 set according to Table A.4 of SR 1997-1: 2004 with those specified in section 3.1 of SR EN 1998-5: 2004/NA: 2007).

At the embankments, the traffic overload was considered in accordance with STAS 1545-89 and STAS 3221-86 (in force on 01-01-2014) as being equivalent to the pressure given by a layer of earth with a height of 1.30 m: q = 1.30 m x 20 kN/m3 = 26 kPa. Up to the height of 6.00 m, the embankments’ slopes have a bank of 2:3. For embankments with a height higher than 6.00 m, the same inclination was maintained, but berms with a width of 3 m were built.

The groundwater level will be taken into account in the worst case scenario, based on the piezometric measurements performed.

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5. Conclusions The limited space did not allow for the detailed presentation of the stability calculations, which can be found in the biographical material belonging to the author of this paper.

It should be noted that the large number of data collected in the field, corroborated and supplemented with the laboratory ones required a laborious statistical processing. Given the importance of the objective under consideration, a choice of the final input data in the stability calculation, imposed a higher responsibility.

The calculation methodology of safety coefficients is not only a common one for such studies, but also a modern one, accepted by the European standards in force.

The results obtained reveal that both the stability of the base land and the structures that make up the motorway as a whole are admissible limits provided that all the auxiliary and protective works foreseen in the project are executed.

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References 1. Pascu, Ileana Stadiul actual al construcției autostrăzii A1 pe tronsonul Deva- Lugoj, Lot 2 (km 27+620m - 47+090m), Raport de cercetare nr. 1, Universitatea din Petroșani, 2016 2. Pascu, Ileana Caracteristicile geomecanice ale terenului de bază şi ale pământurilor utilizate la construcția autostrăzii A1 pe tronsonul Deva- Lugoj, Lot 2 (km 27+620m - 47+090m) și stabilitatea structurii de rezistență a acesteia pe tronsonul analizat. Raport de cercetare nr.2, Universitatea din Petroșani, 2017 3. *** SR EN 1997-1/2004 4. *** SR EN 1998-5:2004/NA:2007 5. *** STAS for determining geo-mechanical characteristics

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ASPECTS REGARDING THE OPTIMIZATION OF THE USE OF HORIZONTAL CENTRIFUGAL COMPRESSORS Caşen PANAITESCU*, Claudia Georgeta NICULAE* Abstract: This paper analyses the possibility of replacing the existing oil seal of axial centrifugal compressors with a dry seal, in order to increase their working performance. Existing dry seal variants have been studied with a view to showing the possible sealing variants of a horizontal centrifugal compressor, as well as the algorithm for calculating the efficiency and power consumed by the compressor.

Key words: horizontal centrifugal compressor, dry seal, oil seal 1. Introduction Converting the available energy in nature into energy, that finally, in various forms, becomes useful in a particular context of industrial activities, materializes through physical processes, which take place in industrial systems and installations, processes named technological processes.

In relation to work systems, the development of these technological processes implies different process strategies. This implies that the distribution of machines and machinery in a working system, which performs that technological process, corresponds to a logical and technological sequence. In essence, a working system comprises an engine machine (mechanical kinetic energy generators) and an engine driven by the machines (in particular, a generating machine or a working machine). The generating machine is the essential machine of the working system, whose functional and constructive solution is directly influenced by the level of effort variables (forces, moments, pressures) and by motion (linear speeds, angular speeds, flows).

Compressors are generating machines that increase the pressure of the gaseous fluids.

Compressors must be driven by an electric motor, internal combustion motor or gas turbine, and they are directly coupled or by means of an intermediate transmission. According to the functional principle (according to the weight of the gas – energy potential energy positioning components, potential pressure energy or kinetic energy) these compressors or gas pumps can be:  Volume compressors - compression is performed by means of a moving element, the volume of closed gas inside the working machine is reduced (intermittently, volumetric volume). The main part is the potential component of pressure. This category includes piston compressors and rotary compressors or blowers. Volume compressors provide a high compression ratio and, depending on the ___________________________________ * Lect.Ph.D eng. University of Oil-Gas Ploiești ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

number of stages, these compressors can have discharge pressures up to 250 MPa. As disadvantages, these compressors make uneven flows rates, they work at low speeds of up to 25 revolutions/minute rpm, and their starting is done without load, and have large size.  Dynamic compressors – characterized by variation of the component of kinetic energy and partly, of the component of pressure energy by passing the gas through a blister engine. The compression process is followed by a partial transformation of the kinetic energy into potential pressure energy.

Dynamic compressors are:  Mono or multi – stage radial centrifugal compressors  Mono or multi – stage axial (horizontal) centrifugal compressors.

These compressors have advantages as compared to other types of constructions, they have a constant flow, they are safe to operate and can be integrated into an automated system. Also, the adjutant of the functional parameters is possibly achieved by changing the engine speed – which can be a turbine (preferably in the case of speeds greater than 60 rpm or electric drive type VFD (variable frequency drive). These types of constructions allow the adjusting of the functional parameters and by rolling the gas into the suction line – the suction pressure is changed. For flows higher than 84 000 (85 000)/ m3/h it is better to use axial compressors than radial compressors, due to the following advantages: higher yields, lower weight, and reduced gauge.  Jet compressors - perform a mixing of a motor fluid (compressed air or steam) with the pumped fluid, resulting in a medium pressure current. These types of construction have no mobile elements (as in the previous cases), and they are provided with ejectors. These are used as vacuum pumps, and constructively are simpler, robust, cheap and easy to operate. As main drawbacks, the ejectors have a low efficiency, they have a slow start, the motor 31

fluid consumption is high, but also the pumped fluid is mixed with the motor fluid (therefore, it is best to use steam as a motor fluid).

2. Types of seals for horizontal centrifugal compressors a. Mechanical contact seals Mechanical contact seals with the role of minimizing losses through axial centrifugal compressor shaft seals (Fig. 1) [1]. These seals have a real sealing surface located between the seal components perpendicular to the compressor shaft, unlike conventional radial seals. This has enabled rotating and stationary components to interact during operation, resulting in improved sealing capability with low seal seals.

Mechanical seals are wet seals, which require the use of oil seals and sealing gaskets, which are complex. Some of the sealing oil can be lost in the

compressor, causing oil consumption, but more importantly, the contamination of the compression process. A portion of the sealing oil comes into contact with the process gas. This sealing oil compromised by the process gas has to be treated / recovered or removed. Disposal of contaminated oil requires compliance with environmental protection procedures. On the other hand, the process – seal gas mixture may cause problems in lowering the ignition point of the oil/gas mixture.

Decreasing the efficiency of the sealing system leads to lower compressor efficiency, which leads to increased energy consumption (from the motor engine), necessary to ensure the functional parameters required by the gas compression process. Therefore, this paper discusses the possibility of replacing this mechanical seal or wet sealing. Further, dried sealing systems will be studied and presented.

Fig. 1. Mechanical contact seals [1] b. Dry Sealing systems Dry sealing systems have a number of advantages, necessary for compressing the gases in the catalytic reformer installation: - Eliminating the contamination of oil pipelines from wet seals and annual savings due to the sealing oil losses and the need to fill it in the tank.

- Savings due to elimination of the system for the transport and regeneration of the oil required for sealing, as well as savings due to the elimination of the nitrogen used for the regeneration of the oil recovered from the wet sealing.

- Eliminating process gas contamination with sealing oil (and, therefore, changing the compressor’s functional parameters).

- Increasing the operational safety and reliability of the compressor

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- Reducing emissions of pollutants into the atmosphere.

1.

Single Gas Seal A single gas seal (figure 2) consists of a single joint seal and a primary seal assembly. Inside the dry gas sealing supply is an internal labyrinth seal that separates the process gas from the sealing gas.

A clean and dry gas is injected between the labyrinth seal and the gas sealing gasket, providing the sealing fluid required for sealing. At the outside of the dry gasket is a gas barrier seal from the compressor shaft bearings. The main function of the sealing gasket is to prevent the lubricating oil from migrating into the gasket.

Gas seals are commonly used only in case of low pressure or non-hazardous process gas applications where they can tolerate operation without a spare sealing system. [2].

Revista Minelor / Mining Revue - no. 3 / 2017

Fig.2. Dry gas seal [1] 2.

Tandem Gas Seal [1] The tandem-style sealing system is most commonly applied, essentially provided with two single –gas seals – a primary seal and a secondary one – seated in a single sleeve. During normal operation, the primary seal absorbs the total pressure drop on the compressor ventilation or ventilation system and the secondary gasket serves as a reservoir if the primary seal doesn’t work. As with single sealing, clean and dry gas is injected between the inner labyrinth seal and the primary

gas seal and the small amount of sealing leakage is directed to the primary ventilation system. Even smaller amounts of sealing gas pass through the secondary seal and outside the secondary valve.

Most of the flow through secondary ventilation is the injection gas injected into the barrier seal.

Tandem gas seals are common in the process gas industry where it is necessary to operate with a safety seal. [2]. Tandem sealing systems have been applied in almost all types of processes to very large sealing pressures.

Fig.3. Tandem gas seal. [1] 3. Tandem Gas Seal with Intermediate Labyrinth [1] This configuration [1] consists of a labyrinth sealing gasket installed in the primary and secondary seals and applies when leakage of seals in the secondary vent cannot be tolerated. It works in the same way as a gas tandem gas seal in that the primary gas seal absorbs the total as a reserve. [2] The purpose of the intermediate seal of the

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labyrinth is to prevent leakage from the primary seal.

To achieve this, the intermediate labyrinth is injected with inert gas at a pressure higher than the vent pressure. Gas labyrinth sealing systems are used in the process gas applications where it is necessary to eliminate leakage of sealing gases to the secondary air, which is often vented locally in the atmosphere.

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Fig.4. Tandem gas seal with intermediate labyrinth [1]

Fig.5 . Double opposed gas seal [1] 4. Double Opposed Gas Seal Double gas sealing is similar to tandem gas sealing, except that the two seals work in parallel in a back-to-back configuration. The dry double seal is made by injecting with an inert gas sealant (e.g. nitrogen), which is injected between the inboard gas seal and the outboard gas seal. To ensure that the process gas in the compressor does not come in contact and eventually contaminate the interior seal, normally a clean and dry washing gas is injected into the inner labyrinth seal. The washing gas is properly treated upstream of the injection point and is provided at a slightly higher pressure than the sealing pressure.

This ensures a positive flow of clean and dry scrubbing gas inside the labyrinth and in the compressor side, which reduces the potential for compressor side, which reduces the potential for contamination of gas sealing, increasing the reliability of gas sealing. Double gas opposed gas 34

seals are used in the process gas applications where it is necessary to eliminate all process gas emissions.

3. Efficiency and power consumed by the horizontal centrifugal compressor [4], [5], [7] The required power to the actual compressor shaft is:

Pe 

Pi

(1)

m

where  m is the mechanical efficiency of the centrifugal compressors ( the loss of shaft friction in the bearing). m  0,97...0,99 .

Pi – is internal power, consumed by a n-stage compressor. This is calculated with the formula:

Pi  n li q m 

nl q m

i

(2)

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li – is the mechanical work or the internal mechanical work consumed in a real stage of a centrifugal compressor for the ∆p pressure increase. This mechanical work considers all the joints inside the compressor, except for mechanical losses through bearing in the bearings.

The mechanical mass consumed (internal) is calculated with the formula:

li  l 0

qm  q p qm

 lf

(3) qp - is the mass flow rate of loss through leakage; lf – is the massive mechanical work consumed to overcome the friction between the gas and the rotor; lo – is the mechanical work required to achieve the pressure increase ∆p, which takes into account the deviation of the gas flow at the inlet to the rotor, the friction from the interior of the gas and the walls of the channels through which it flows; qm – mass flow;

 i –the internal yield of the centrifugal compressor

stage (all losses considered) is defined by the ration:

i 

l li

(4) l – is the theoretical mass mechanic (not all frictions and losses are taken into consideration).

This theoretical mass mechanic is determined by the actual process of gas in the compressor: a. isothermal, when there is no gas leakage through sealing and no friction between the rotor and the gas; b. adiabatic, when heat does not change with the environment; c. polytropic, when there is no gas leakage through sealing and no friction between the rotor and the gas. [4]

Taking into account these aspects, the appropriate internal yields can be defined: adiabatic internal yield: l (5) i ,ad  ad li internal isothermal yield: l (6)  i ,iz  iz li polytropic internal yield:

i , p 

lp li

(7)

where lad , liz şi l p represents the mechanical work required for adiabatic compression, isothermal, polytropic respectively.

Gasodynamic yield is a characteristic of the quality of gas dynamics processes of the compressor stage (similarly, hydraulic efficiency of the hydrodynamic generators) and is defined by the ratio:

 gd 

l l0

(8)

4. The study of dry sealing at the catalytic reformer at the horizontal centrifugal compressor from the catalytic reformer installation of a petroleum refinery This paper has studied the possibility of replacing the existing oil seal of the axial centrifugal compressor with a dry seal.

The compressor for this study is driven by a 35 bar backpressure turbine with the output power of 1980 kN and speed of 6670 rpm.

The compressor operating parameters are shown in the table 1. The schematic of the compressor integration in the catalytic reformer installation is shown in the figure 6.

Table 1 Operating parameters for axial centrifugal compressor Operating parameters Value Discharge flow in normal conditions 550000 – 112760 Nm3/h The suction temperature 38 0C Discharge temperature 69,5 – 74 0C Suction pressure 9,50 bar Discharge pressure 12,00 bar Differential pressure 2,50 – 3,50 bar Compression ratio 1,34 – 1,40 Gravimetric flow max 33650 kg/h The power absorbed by the compressor shaft 1500 – 1800 kW Speed of the rotor shaft 4700 – 5800 rot/min The average steam consumption of the turbine 16 – 18000 kg/h Min/Normal/Max steam temperature 290 / 310 / 350 0C Inlet steam pressure – min/normal/max steam 30 / 35 / 42 bar

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Fig. 6. The horizontal centrifugal compressor in the RC installation [3] Let’s consider the case of a compressor fitted with an oil seal, where a leakage loss of a mass flow qp will occur, losses which will lead to an increase of the power consumed by the compressor Pem, so it will increase the energy consumption (from the motor machine) (figure 7).

Figure 7 shows the variation curves of the functional parameters of the axial horizontal centrifugal compressor.

The gases conveyed by the axial centrifugal compressor have the composition shown in table 2.

Tabel 2 The volumetric composition of recirculated gases Component Composition, procent vol, Hydrogen 80,24% Methane 5,80% Ethane 5,83% Propane 4,43% Butane 2,42% Pentane 1,25% Hexane 0,03%

H, Hr, Pc, 

Pi* Pi

Cazul 1) Cazul 2)

Hr P

Hproces H*proces H0

P*



H*

H

* Q* proces Q proces

Q

Fig. 7 The curves of the functional parameters of the axial horizontal centrifugal compressor Case 1) is the case of the axial horizontal centrifugal compressor with the internal characteristic ă H=H(Q) and the operating point P. the functional parameters made in the installation are (Qprocess, Hprocess). The compressor yield is  , and the power consumed according to the formula (2), is Pi Case 2) is the case where the gas leakage occurs in the compressor. It observes, in addition to a decrease in flow and load and a decrease in efficiency and an increase in power consume by the compressor.

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5. Conclusions The study has emerged from the need to increase the working performance of the axial centrifugal compressor from the catalytic reformer installation in an oil refinery. This paper proposes replacing the existing sealing of the centrifugal compressor with a dry mechanical seal; this is a technical solution that allows the elimination of deficiencies in operation and the obtaining of technical and environmental benefits.

Revista Minelor / Mining Revue - no. 3 / 2017

References 1. Stahley J.S. Dry gas seal Handbook, PennWell, 2005.

2. *** API617- Axial and Centrifugal Compressors and Expandder-compressors, Eight Edition, September 2014 3. Suciu Gh., Bohiltea I., Platon Al. Ingineria prelucrării hidrocarburilor, vol. III, Editura Tehnică. 1986

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4. Berzănescu A. Calculul și construcția utilajului petrolier, Editura de Stat Didactică și Pedagogică, 1961 5. *** http://turbolab.tamu.edu/proc/turboproc/T11/T11113120.pdf 6. *** www.slideshare.net/kstnhdk54/dry-gas-seal-systems 7. *** www.slideshare.net/draghunathan/compressorstraining-sessions

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AGIR PRIZE - 2016 MINING WITHIN ROMANIA’S SUSTAINABLE DEVELOPMENT Domain: Mineral Resource and Energy Engineering

In 2016 the Technical Sciences Academy of Romania published the paper ”Mining within Romania’s sustainable development” – authors Professor Dumitru Fodor, D. Eng. – paper coordinator, Professor Mircea Georgescu, D. Eng., Assoc. Prof.

Viorica Ciocan, D. Eng., Gavril Baican, D. Eng., Ervin Robert Medveș, D. Eng., Ioan Călin Vedinaș, D. Eng., Ovidiu Gâlcă, D. Eng., Emil Huidu, D. Eng., Gheoghe Iordache, D. Eng., Tiberiu Trotea, D. Eng., Eng. Aurel Pantea Lazăr, Eng. Ioan Nicoară, Eng. Sorin Găman, Eng. Ștefan Ghioc The paper was conceived by a group of specialists, knowing the real situation of Romanian mining, who made clear analyses and relevant suggestions for the recovery and revitalization of mining in Romania.

Starting from the statement that mining represents a key area for the economic revival and development of the country, the paper aim was to analyse the current situation of Romanian mining, after the reorganizations from the past decades and to name the mining objectives which should be kept active and the ones 38

Revista Minelor / Mining Revue - no. 3 / 2017

which are closed but can be brought back to operation in the new economic conditions to satisfy the interests and needs of the economy. The paper is highly complex as it analyses the mining situations for all minerals in the mines in Romania.

The paper starts with presenting the country’s mineral richness, the exploitation methods and work technologies used and the results in time of this work.

In the activity of capitalizing the Romanian mineral deposits, classic technologies were used both

for exploitation and for preparation at the level of those applied all over Europe and worldwide.

In the last few years the mining production capacity of Romania has diminished compared to the one before 1990.

Table 1 presents the productions of various mineral substances and rocks during 2010-2015. In general, we observe that now we produce below 100 million tons per year, while coal production, metal and non-metal minerals represent only 1/5 of the production of such minerals before 1990.

Table 1 The evolution of physical production for various minerals, period 2010 – 2015 (Reported production to ANRM) Substance or mineral group Coal Non-iron ores Iron ores Non-metal ores Rock salt Liquid salt Useful rocks, type: Sand and gravel others Ornamental rocks, of which: Marble

U.M.

2010

2011

2012

2013

2014

2015

(thousand t) (thousand t) (thousand t) (thousand t) (thousand t) (m3)

31.183,01 13,12 1.052,33 2.353,51 97.626,00

36.062,02 33,42 3,18 1.056,47 2.219,22 98.416,00

33.460,13 31,70 8,99 981,79 1.867,49 69.637,00

24.787,00 38,51 21,30 1.234,23 2.113,75 45.980,00

24.773,69 40,26 12,66 1.024,10 2.042,34 14.435,00

26.705,77 21,77 40,26 1.222,48 2.079,59 13.333,00

(thousand m3) (thousand t) (m3)

25.132,05 31.953,67 25.229,67

31.358,49 44.363,85 22.674,00

32.369,57 43.455,14 19.296,00

26.753,77 36.738,85 37.295,00

26.689,12 35.115,67 18.398,00

38.830,33 40.091,39 26.929,00

11.920,15

12.726,12

8.887,96

8.363,80

7.138,30

7.189,31

(m3)

In the first part of the paper I mentioned the background reorganization of the mining industry which consisted in:  Technologic reorganization of the production in mining units which exploited lignite, black coal, copper and precious metals;  Managerial reorganization of all mining units by detaching complementary basic or complementary activities and reorganizing them in distinct private units;  Employee reorganization, mainly by massive reduction in numbers using two ways: retiring them through reducing the work period and dismissing them through compensations;  Limiting or stopping the production in some mines or open pits with small deposits or in the ones with extremely high production costs.

We underline that there were taken out of the system more than 150,000 people working in mines and the 11 Government Decisions decided the closure of 556 mining and preparation units with their tailing ponds and sterile dumps, all over the country.

Furthermore, the paper analyses the activity of the Romanian mines which are currently operating.

First, there was an analysis of the situation of the energy production substances (coal, uranium) and the way they may support, in time, the energy sector in Romania.

ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

Today, the world goes through a transition period regarding the energy resources. It tries to use renewable resources as much as possible as an alternative to the classic resources – coal, oil, and gas.

Coal in Romania was and still is a main source for the energetic security of the country, but its use has two important problems needed to be solved:  The cost of coal going to thermal power plant  The need to reduce the carbon dioxide released into the atmosphere through gas burning.

These problems lead to the increased tendency to use renewable energy resources with low pollution degree which have also two problems needed to be solved:

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- The continuity and inconsistency in energy production through the renewable system - Building systems for long term storage of renewable energy generated by the renewable system.

As a result, we underline the following: 1. The transition to new energy resources should be regulated by using energy capacities of adjustment based on fossil fuels; 2. To maintain a constant national energy capacity, there comes the need of an energy compensation system which may be done also based only on fossil fuels; 3. The increase of the energy demand for the economy, on a short-term period, may be carried out only based on classic fuels and, as a result, there comes the need to keep the coal exploitations and thermal power plants in operation, in order to overcome these situations.

The conclusion is that the two systems should operate strongly connected to one another. We consider that irrespective of the results obtained in the fields of energy storage and carbon dioxide emissions reduction, coal will be used furthermore in thermal power plants, at least until the half of this century.

In the analysis of the mining sector, to support the electric and thermal energy production, we based on an energetic mix considering both coal and uranium. The energetic mix considered regards coal (25-30 %) and nuclear energy (20-25%).

The estimations are made until 2035-2050, as we don’t know which the achievements in the fields of energy storage and reduction of carbon dioxide emissions from thermal power plants are going to be.

We forecast that in the future in Romania, the coal energy sector will give 6,500 MW, the hydroenergy sector will give 6,500 MW, and the nuclear sector will give 1,413 MW, while the other remaining will be given by hydro-carbs and renewable resources from the market.

From the analysis of this activity sector, the conclusions are the following:  Keeping into operation three energy sectors of the thermal power plants in Paroșeni and Mintia (one group in Paroșeni of 150 MW and two groups in Mintia of 210 MW each) of the Black Coal Energy Complex – Hunedoara County;  Keeping into operation four mines in the Jiu Valley (E.M. Lonea, E.M. Livezeni, E.M. Vulcan and E.M. Lupeni) to supply coal for the thermal power plants Paroșeni and Mintia;  Keeping into operation 12 energy groups (considering the rehabilitation programs in development) of the four biggest thermal power plants: Rovinari, Turceni, Ișalnița and Craiova II, included in Oltenia Energy Complex whose 40

open pits will supply 20-23 million tons of lignite every year needed for their optimal operation;  Keeping into operation groups 1 and 2 and building groups 3 and 4 of Cernavoda power plant, to ensure the production of electric energy based on fossil fuels and renewable resources (hydro, wind and photo-voltaic etc.) according to the suggestions for the development of the energy sector in Romania, considering that 20% of the electric energy should come from nuclear power plants.

To extract the supply of nuclear fuel from Romanian resources, they suggested the opening and exploitation of the deposits of Tulgheș-Grințieș.

Also, the secondary uranium resources from dumps and tailing ponds and those from underground waters with low uranium concentrations might be capitalized.

Furthermore, there is an analysis of the metal ore sector, underlining the deposits which can be taken into consideration for exploitation. For a series of better known deposits, there were calculated the metal amounts possible to be obtained in the current conditions of efficiency, as follows: 2,165,000 t copper, 150,000 t zinc, 102,000 t led, 2, 000 t silver, and 350 t gold.

Sustainable mining can be done through processing and exploiting mining wastes for retrieving useful substances from the existing dumps and tailing ponds, followed by the storage of future wastes in safe conditions in areas which no longer represent a threat for communities and without affecting the environment, enabling the rehabilitated areas where dumps were placed to carry out other activities that replace mining.

In the future, there is a need for a national program to observe and quantify the reserves of mineral ores possible to be retrieved from the dumps and tailing ponds in Romania. No country can afford not to take into consideration this potential of metal and mineral ores from such deposits.

Revista Minelor / Mining Revue - no. 3 / 2017

The conclusions of metal ores issues are as follows: 1. The capitalization of deposits with small contents of substance but large reserves, possible to be exploited in open pits. We currently know several such deposits, such as: Roșia Poieni, Moldova Nouă, Valea Morii – Brad, Bolcana for copper and Aurum (Borzaș), Nistru (Galbena – Lăpușna), Certej, Roșia Montană etc. for gold and silver.

2. Processing the mining residues from dumps and tailing ponds with metal content, such as: Bozânta pond (Remin), Central Flotation pond – Vechi (Remin), Rovina pond – Brad, Ribița-Curteni pond – Brad and others.

3. Opening the deposits which may be capitalized economically through underground mining is welcomed, in conditions of economic efficiency (mines Cavnic, Baia Sprie, Turț-Ghezuri, Șuior and others). For a series of mines they decided their termination, even if they had important amounts of usable reserves and the units held valid exploitation licenses.

4. Opening the deposits with rare mineral ore contents, which become highly interesting in the current technical-economic context and worth to be taken into consideration in the future.

Romania is a country rich in non-metal ores and useful rocks, a reason why this paper analyses the deposits having a high importance for the economy.

In the future, if required, they may increase the production of rock salt and solution salt, construction materials and non-metal ores needed for different industrial works.

In the case of non-energy products, Romania should develop complete cycles of exploitation – preparation – processing. A negative impact on the economy is that non-iron metal ores are capitalized by export as concentrates, not going through the complete cycles of metallic processing (i.e. copper, gold, silver etc.)

All the deposits that have to be exploited currently benefit from modern access ways to the work points, energy and drinkable or industrial water access and a surplus of workforce with possibilities of being employed in the mining field.

ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

At the end of the paper, the authors display a series of concrete suggestions aimed to revive mining in Romania, as follows: 1. To revive the extraction activity and capitalize the mineral ore deposits, the ministry should ensure an adequate legislation and institutions able to operate the mining sector and to provide the financing sources.

2. The foundation of a national service of mining inspection to survey the rational exploitation of mineral ore deposits.

3. Resuming the activities of geologic prospection of the deposits in order to acknowledge the reserves.

4. National companies, mining companies and other economically interested / responsible entities should draw out feasibility studies to establish technical and financial conditions required to resume the mining activity to reopen and exploit the potential deposits.

5. The identification of new sale markets, especially for export, on energy and metal stock exchange.

6. The ministry together with ANRM should analyse the possibility of capitalizing the materials whose industrial use has grown substantially in the past few years; for example, graphite has turned into an important raw material in electronics and the world economic conditions are different compared to those at the time graphite exploitation was stopped in Romania.

7. The development of extractive activities in holdings exploitation – preparation / processing – use / capitalization, or in public – private partnerships.

8. The development of S.N.S. Salrom S.A. Bucharest towards other auxiliary activities generated by exploitation, especially the use of underground vacuums generated by salt extractions. These caverns may be used for the storage of resources such as natural gas, deposits for various products which demand certain temperature or humidity conditions.

The paper is important both theoretically and practically and can be applied to all the mining basins in Romania, being useful to specialists who regard the future of Romanian mining and to regional and national administrations connected to 41

the revival and sustainable development of the economy.

The paper was displayed and debated in the Presidium of the Romanian Technical Sciences Academy and the summary and conclusions were distributed to the central country administration – Parliament, Government, ministries, political parties, County Councils, Union Federations, etc.

The impact of the paper on the administration was positive, a lot of appreciation letters being received, while all the County Councils were interested in developing mining in Romania.

On the 6th of September 2017, the paper was presented and debated before the Commission of Industry and Services in the Deputy Chamber – Romanian Parliament. Senators and deputies, representatives of ministries, unions, national agencies, economic environment and high education took part in the debates.

All the speakers have appreciated the importance of mining for the national economy and expressed the availability to help the revival and development of this sector in Romania, in the years to come.

In the end, we consider that in the future period, in order to revive mining, it is necessary to elaborate a mining strategy and a Mining Law, which should match the current requirements, promote, and mainly consolidate the following aspects:  The role of Romanian Government should be to control and promote mining, to exercise the position of owning mineral resources through organizing a stable, competitive and fair system of mining taxes and royalties;  The role of private companies should be to promote projects, ensure funding and mining activity management and to hold the responsibilities concerning the getting of exploitation licenses.

The paper was part of AGIR competition and, on September 14th, 2017, during the General Meeting of AGIR it was given AGIR – 2017 prize, in the domain of ”Natural resources and energy engineering”.

Prof. Ph.D eng. Dumitru Fodor Ph.D eng. Ioan Călin Vedinaș

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