Nr1en2017 by Univ Petr

Revista Minelor Mining Revue AN INTERNATIONAL JOURNAL OF MINING AND ENVIRONMENT Vol. 23 No. 1 / 2017 ISSN-L 1220 – 2053 / ISSN 2247 -8590

Published by: University of Petroşani

REVISTA MINELOR - MINING REVUE EDITORIAL BOARD Editor in chief: Prof. Ilie ONICA Associate editors: Lect. Paul Dacian MARIAN Lect. Lavinia HULEA Senior editors: Prof. Dumitru FODOR Prof. Nicolae ILIAŞ Prof. Mircea GEORGESCU Scientific committee: Prof. Iosif ANDRAS - University of Petroșani, Romania Ph.D eng. Marwan AL HEIB - Ecole des Mines de Nancy, INERIS, France Prof. Victor ARAD - University of Petroșani, Romania Prof. Lucian BOLUNDUȚ - University of Petroșani, Romania Prof. Ioan BUD - Universitatea Tehnică Cluj-Napoca, Romania Prof. Mihai Pascu COLOJA - Universitatea de Petrol și Gaze din Ploiești, Romania Prof. Ştefan COVACI - University of Petroșani, Romania Prof. Eugen COZMA - University of Petroșani, Romania Prof. Nicolae DIMA - University of Petroșani, Romania Prof. Carsten DREBENSTEDT - TU Bergakademie Freiberg, Germany Prof. Ioan DUMITRESCU - University of Petroșani, Romania Ph.D ing. George-Artur GĂMAN - I.N.C.D. INSEMEX Petroşani, Romania Prof. Ioan GÂF-DEAC - Universitatea Dimitrie Cantemir Bucureşti, Romania Ph.D eng. Edmond GOSKOLLI - National Agency of Natural Resources, Albania Prof. Mircea GEORGESCU - University of Petroșani, Romania Prof. Monika HARDIGORA - Technical University of Wroclaw, Poland Prof. Andreea IONICĂ - University of Petroșani, Romania Prof. Alexandr IVANNIKOV - Moscow State Mining University - Rusia Prof. Oleg I. KAZANIN - National Mineral Resources University of Sankt Petersburg, Rusia Prof. Vladimir KEBO - Technical University of Ostrava, Czech Rep. Assoc.prof. Charles KOCSIS - University of Nevada, Reno, U.S.A. Prof. Sanda KRAUSZ - University of Petroșani, Romania Prof. Maria LAZĂR - University of Petroșani, Romania Prof. Monica LEBA - University of Petroșani, Romania Prof. Per Nicolai MARTENS - RWTH Aachen University, Germany Prof. Roland MORARU - University of Petroșani, Romania Prof. Jan PALARSKI - Silesian University of Technology - Gliwice, Poland Prof. George PANAGIOTU - National Technical University of Athens, Greece Prof. Lev PUCHKOV - Moscow State Mining University, Russia Prof. Pavel PAVLOV - University of Mining and Geology St. Ivan Rilsky Sofia, Bulgaria Prof. Sorin Mihai RADU - University of Petroșani, Romania Prof. Ilie ROTUNJANU - University of Petroșani, Romania Ph.D eng. Raj SINGHAL - Int. Journal of Mining, Reclamation and Environment, Canada Prof. Mostafa Mohamed TANTAWY - Assiut University, Egypt Prof. Mihaela TODERAȘ - University of Petroșani, Romania Prof. Lyuben TOTEV - University of Mining and Geology Sofia, Bulgaria Prof. Ingo VALMA - Tallin University of Technology, Estonia Assoc.prof. Ioel VEREȘ - University of Petroșani, Romania Prof. Yuriy VILKUL - Technical University of Krivoi Rog, Ukraine Prof. Işik YILMAZ - Cumhuriyet University, Turkey Acad. Dorel ZUGRĂVESCU - Geodynamics Institute of the Romanian Academy, Romania

CONTENTS

Dumitru FODOR, Tiberiu TROTEA Coal in the future of Romanian energy

Dacian-Paul MARIAN, Ilie ONICA, Ramona-Rafila MARIAN, Dacian-Andrei FLOAREA Surface subsidence prognosis using the influence function method in the case of Livezeni Mine

Marius STAN, Lazăr AVRAM, Sorin AVRAM, Thair AL SHAMI Operating the oil production facility with solar panels and wind generators

Doru ZDRENGHEA, Corina CHIOTAN Design of Zam 1 tunnel conceptual, technological and structural elements

Izabela-Maria NYARI (APOSTU), Maria LAZĂR, Florin FAUR Implementation of sustainable practices in the lignite open pit Roșia de Jiu

COAL IN THE FUTURE OF ROMANIAN ENERGY Dumitru FODOR*, Tiberiu TROTEA** 1. Introduction Considering the use of primary energy resources in time, we notice that in the 19th century coal was used as a main resource, in the 20th century oil replaced coal, while in the 21st century we expect gas and renewable energy resources to be dominant. Although exploited and used for centuries, the current quantity of coal known today – over 900.000 million tons – represents 90% of the fossil fuels compared to only 5% oil and 1% gas. Coal remains, owing to its quantity and quality, an important global energy reserve and, if capitalized efficiently, will serve mankind for a long time in the future. The National Energy Strategy, currently under public debate, regards the operation, modernization and development of the energy system, having as targets for years 2030-2050 the providing of the energy required by the national economy and the observing of the limits imposed by the European Union through the recently adopted Energy Strategy, which stipulates: - A 40% reduction of greenhouse gas; - The share increase of renewable energy to 27% within the total consumption of electric energy; - A 27% increase of the energy efficiency as compared to 1990. 2. Energy resources in Romania In Romania the current and future energy resources are: - Fossil fuel resources (coal, oil, gas); - Nuclear resources; - Hydropower resources; - Renewable resources (wind, photovoltaic, biomass, etc.). Romania owns a significant number of energy resources, including gas, oil and coal. The current exploitable deposits of gas are over 180 billion m3, exploitable oil represents over 70 million tons, while exploitable coal represents over 100 million tons of black coal and about 1,300 million tons of lignite and brown coal. Today, Romania deals with a transition period towards the increasing use of renewable energy resources. Romanian coal remains an essential source for the energy stability, but its use has to face two issues: coal costs and the need for * Prof. Ph.D eng., University of Petroșani ** Ph.D eng., Oltenia Energy Complex 2

reducing the amount of CO2 discharged through burning gas into the atmosphere. These issues lead consequently to the increased tendency of using renewable energy resources with a lower polluting degree, which, nonetheless, display, at their turn, two major issues: - The discontinue and uneven production of energy - The lack of large scale methods, economically and technically efficient, for storing the energy, which guarantee the capacity of providing energy during several weeks. Due to these major problems, two systems of energy supply for the national energy system are required: a system of thermoelectric plants, continually available, and a system of energy supply from wind and photovoltaic sources. In 2014 the production capacity of the National Energy System represented 24.5 GW, of which 21.1 GW available energy, as follows: - Coal thermoelectric plants 5.16 GW - Gas thermoelectric plants 3.65 GW - Hydroelectric plants 6.74 GW - Nuclear plants 1.41 GW - Renewable energy 4.13 GW The production and use of electric energy from renewable resources needs flexible and stable partners, which, in Romania, are represented by energy groups that use coal or other fossil fuels. The increase of national energy demand can be carried out in a short time, based only on classic fuels and, consequently, hence the need to maintain the coal exploitations and plants which use these fuels in order to overcome such shortcomings. The necessity of transition towards the renewable energy production is valid, but should be done according to a long term plan. The transformation of energy supply in Romania can only be controlled by coal. Therefore, the Romanian Energy Strategy should pay more attention to coal. In 2015 Romania produced 47.5 TWh and the energy production structure was as follows: 28% coal 13.3 TWh 27% hydro 12.8 TWh 18.5% nuclear 8.5 TWh 13% gas 6.2 TWh 11% wind 5.23 TWh 2% photovoltaic 0.9 TWh 1% biomass 0.4 TWh While analyzing the mining sector with a view to supporting energy production, we used the Revista Minelor / Mining Revue - nr. 1 / 2017

requirements of the National Energy Strategy which shows that, compared to 2015, in 2030 the coal will provide only 10% of the national electric energy, hydro 27%, gas plants 24%, nuclear 17% and renewable energy 22%. We notice that in 15 years the quantity of energy given by the nuclear and renewable plants will double, while the coal energy produced will be halved. Hydro and gas energy will maintain the same level. The estimations are done until 2035-2050 as we cannot predict the achievements in stocking the energy and in collecting and storing CO2. In establishing the National Energy Strategy the following aspects were considered: 1 – The energy demand in the near future and between 2030 and 2050; 2 –The electric energy production capacities Romania needs to ensure its energy independence and the safety of the National Energy System and whether energy should be imported or not; 3 – The structure of energy producers, considering the maximization of the energy resource national base; 4 – The opportunity of new investments in production capacities, considering the existence of a production overcapacity of more than 50% than the current energy demand at the level of the country, and also considering the necessity of replacing older capacities, physically and morally worn-out; 5 – The development of new energy production, storage and transport technologies is a challenge which may influence, on long term, the choice of a scenario for new production capacities and investments; 6 – The definition of energy market considering the enlargement of intra-community connections as a major requirement of the European Union; 7 – The need for electric energy considering its use for residence heating and food preparation, replacing gas consumption and reducing CO2 emissions; 8 – The sustainability of energy costs by the population. It is assumed that in the future, within the total power required by Romania, the thermoenergy system will ensure 3,400 MW, the hydro will ensure 6,500-6,800 MW, while the nuclear would provide, at least, 1,413 MW. The rest will be provided by hydrocarbs and renewable resources. Irrespective of the results obtained in energy storage and CO2 collection and depositing, coal will be used, at least, until the middle of the current century.

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

Today Romania has 6 large thermo power plants and 10 middle and small ones that use coal from the Jiu Valley and Oltenia Coal Basins. The analysis made by the authors reveals a series of aspects regarding the future functioning of coal-based thermo-power plants. 3. Coal based thermo-power plants analysis The thermo-power plants within Hunedoara Energy Complex (Mintia and Paroșeni) own a power capacity of 1,435 MW, being the only energy production plants in the centre and NorthWestern parts of Romania, operating now to an average level of 350 MW. The plants were designed to operate and to consume the entire black coal production of about 2.5 million tons / year, for a coal power of about 4,000 kcal/kg. There are 4 large operating mining units in the Jiu Valley, which can provide a production capacity of 2.055 million tons/ year of black coal (E.M. Lonea 380,000 tons / year, E.M. Livezeni 636,000 tones / year, E.M. Vulcan 400,000 tons / year and E.M. Lupeni 639,000 tones / year). This production ensures the functioning of the energy plants in Paroșeni and Mintia: one energy group in Paroșeni of 150 MW and two energy groups in Mintia of 210 MW each (groups 3 and 4). The four mining units own about 47 mil tones of black coal exploitable reserves and need in the future years, based on feasibility studies, investments of about 150 million Euro, consisting in mining equipments and underground and surface mining works. The modernization process of mining will be accompanied by activity reorganizing and personnel decrease. The thermo-power plants require investments of 174 million USD, to solve the environment and fitting problems at Mintia thermo-power plant. We believe that through providing the investment funds and the technical and organizational measures taken by the Ministry and the management of Hunedoara Energy Complex in order to improve the situation, the mining and energy activities will be able to operate efficiently. Therefore, we hope that we can avoid the firing of hundreds of miners and energy workers in Hunedoara County, avoiding a major social impact for the population. Recently, the technocrat Government during the period 2015-2016 decided that only two mines would operate in the future (Livezeni and Vulcan) in the Jiu Valley, while, in Hunedoara County, the thermo-power plants of Paroșeni and Mintia would

operate each with only one energy group of 150 MW and 210 MW. As a consequence, they decided the firing, beginning with October 1st, 2016, of 840 workers, as follows: 452 energy workers from Mintia Thermo-power Plant, 100 energy workers from Paroșeni Thermo-power plant and 288 miners from the Jiu Valley mines. As far as the thermo-plants powered by lignite are concerned and considering the increase of the given power through renewable resources especially wind power - and the decrease of electric energy consumption, the average power produced in the past years decreased. A part of the coal based energy groups of plants were replaced by gas powered groups (Oradea, Arad) and the thermoplant from Halanga – Drobeta Tr. Severin was turned off in 2015 together with the heavy water plant. Today, the consumers of the lignite produced by the mines in Oltenia are the thermo-power plants in Rovinari, Turceni, Craiova and Ișalnița, part of CE Oltenia and the thermo-power plants of CET Govora, Colterm Timișoara, UATA Motru, public institutions and local residence consumers. The four thermo-power plants part of CE Oltenia include 12 energy groups with a total installed power of 3,570 MW. Analyzing the modernization-rehabilitation programs of the energy groups included in CE Oltenia, it appears that, in the future, Rovinari Plant will only own four active groups of 330 MW (groups 3, 4, 5 and 6), Turceni Plant - four groups (3, 4, 5 and 7), Ișalnița - two groups (7 and 8) of 315 MW, all condensing, while Craiova II Plant two CHP groups of 150 MW each, ensuring the heating of the city of Craiova. The objectives of the modernizationrehabilitation programs were: - The increase of time and energy availability of the block; - The increase of the functioning period of the energy block by 15 years; - The increase of the technical-economic parameters of the energy block through reducing the heat specific consumption; - The improvement of the environment condition through reducing the CO2 emissions from 1.58 t / MWh (1989) to 0.96 t CO2 / MWh currently, reducing the NOx emissions to 500 mg / Nmc and the powder concentration in the burning gas to <50 mg / Nmc; - The introduction of modern automation and control systems to perform the technical connections to UCTE;

Together with the modernizationrehabilitation of the energy groups they also built the desulphurization installations and the exhaust installations for slag and ash from burning, in order to reduce the SO2 and dust emissions to the E.U. standards. The desulphurization installations of the energy groups are meant to reduce the SO2 emissions from 4000 mg/Nmc before 1990 to 200 mg/Nmc currently and may contribute to new investments as they produce gypsum in the process of washing the burning gas with chalk. As a consequence, beside Turceni plant, they built a drywall factory, which uses the gypsum produced by the desulphurization installations of the plant. The mixture of slag and ash may be used as construction materials for platforms and embankments, according to recent studies. This means that, for about 20 years, the electric energy production based on lignite will have values between 17 and 22 TWh, which will generate a lignite consumption of 20-23 mil tones / year. If newer groups will be established, through increasing the burning efficiency from 32-34% currently to 42-45%, the electric energy production may be 30% higher. The lignite exploitation to fuel the four thermo-power plants of CE Oltenia occurs in 10 open mines: Tismana I, Tismana II, Rovinari-Est, Pinoasa, Roșia Jiu, Jilț Sud, Jilț Nord, Roșiuța, Lupoaia, Hușnicioara, equipped with continuous extraction technologies, which may extract lignite production of about 27-28 mil tones / year. At Rovinari Plant, for an electrical energy production level of about 8.6 TWh / year, the lignite consumption at an average calorific power of 1,800 kcal / kg (7.6 Gjoule / kg) would be about 9.7 mil tones. The exploitable reserves of Pinoasa, Tismana I and Tismana II open pits are over 140 million tones, and the Roșia de Jiu pit is about 200 mil tones. These four pits may supply Rovinari plant so that it achieves the electrical energy production level of 8.6 TWh / year, during the following 35 years. Lets notice that after 35 years the pits have the capacity to be developed in the neighbouring perimeters. Roșia pit may extend in the Fărcășești perimeter with reserves of 160 mil tones and an overburden ratio of 11 to 1, and the Valea cu Apă perimeter with reserves of 120 mil tones and an overburden ratio of 12.5 to 1. Pinoasa ownd additional resources of about 500 mil tones and an overburden ratio of 7.7 to 1.

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For Turceni plant, considering the same production levels of 8.6 TWh / year, the pits of Jilț Sud and Jilț Nord, with a cumulated reserve of 210 million tones, may ensure the consumption during more than 20 years. Jilț Sud may extend on Tehomir perimeter with reserves of 120 mil tones and an overburden ratio of 7.8 to 1. Turceni plant has the possibility to be supplied with coal from Rovinari and Motru basins. As for the electric and thermal energy produced by Ișalnița and Craiova II plants, it is evaluated to 4.5 TWh / year, with a yearly consumption of about 5 mil tones of lignite. The coal may be supplied by the pits Roșiuța – Lupoaia, Motru basin having deposits of about 150 mil tones, estimated to operate for 30 more years. As the reserves from Lupoaia pit are exhausted, the equipments may be transferred to the future pit Ploștina Nord with reserves of over 50 mil tones, supplying the two plants for 10 years with an overburden ratio of 7.7 to 1. The four thermo-power plants included in CE Oltenia, namely Rovinari, Turceni, Ișalnița and Craiova II, the current favourable reserves (with an overburden ratio of 6 to 1) of over 700 million tones ensure the electrical energy production level of 22 TWh for 28 years with the current performance of the groups (efficiency of 32-34%). The current consumption of Govora thermoplant is about 1.8 mil tones / year, but in time, depending on the decisions concerning the evolution of the units at the Râmnicu Vâlcea industrial platform, it may be modified. The lignite is provided by the mining basin Berbești, from the pits of Olteț and Berbești. ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

Considering the development of production capacities of renewable energy (of more than 3,757 MW at the end of 2103, of 60% increase compared to 2012), of gas plants, the solution of keeping the lignite thermal-plants in operation is the reduction of coal costs and also the processing costs of the thermal-power plants. This requirement may be ensured through focusing the extraction on the most efficient perimeters, through modernizing the extraction equipments of the pits, through making flexible schedules based on demand, in order to provide a cost price at the level of the thermo-power plant between 11.5 – 12.5 Euro / ton, calorific of 1,7001,800 kcal / kg and through building new energy groups equipped with boilers of overcritical parameters. The average and long term strategy of CE Oltenia stipulates modernizing actions for the energy groups, the achievement of a prototype project for the collecting, transport and storage of CO2 (CCS – Getica), and the building of new capacities with high efficiency. Aside from the measures stated above, the future lignite extraction activity should be concentrated in mining perimeters of high economic efficiency, unviable or close to depleting mining objectives (Gîrla, Rovinari Est, Hușnicioara, Peșteana Nord, Lupoaia, Panga, Berbești Vest) should be terminated, while technologic fluxes should be optimized; pits equipments and installations should continue modernization programs as well as the increase of usage indexes of transport equipments.

In the future, considering that the average life of transport equipments used for excavators or dump cars is over 50 years (compared to 40 years as planned), the investments should be directed to the rehabilitation of operating equipments with planned lifetime reached. Another action should be directed towards the rehabilitation of affected lands to ensure the expropriation in the advance of pits â&#x20AC;&#x201C; this being the most important problem of the mining operators in Oltenia.

4. Conclusions In order to participate to the energy market, the mines which provide the fuel needed for the thermal-power plants, both based on black coal or lignite, must carry on their development processes through modernization-rehabilitation.

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The maintaining in the energy mix of the thermal-power plants based on coal, according to the actions described above, should be done with a view to reduce the production costs of MWh so that the selling price should be competitive on the energy market in Romania; nonetheless, this is not possible provided that: - They do not reorganize energy producers so that the electrical energy market becomes competitive among companies with energy mixes, similar to the others in Europe (RWE – Germany, ENEL – Italy, CEZ – Czech Republic and others)

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- Two units (3 and 4) will be built at Cernavodă, without a strict analysis of costs, compared to building two coal based energy groups of 600 MW each, with all implications related to environment, fuel, system energy integration, etc. - The pumping station of Tarnița will be built in order to balance the energy system without considering balancing it owing to hydropower plants from water storage, while the coal thermoplants will operate in-line, a fact that would lead to their increased efficiency which will reduce the production costs by 5-7% for every coal based MWh.

Lets end by emphasizing that the most important concerns of the authorities are: the optimization of the exploitation process of the lignite deposits, exploitation modernization, regulation of the legal issues related to land ownership, financial sanitation of the units, personnel sizing, labour reconversion depending on the area requirements, while noticing the major role of coal in the production of electrical energy in Romania. Moreover, it is known that the only producer of electrical energy – not depending on conditions – is coal which exists in large amounts in Romania.

References 1. *** Romanian Energy Strategy perspectives for 2050

2016

–

2017

with

2. D. Fodor, T. Trotea Coal in Oltenia – Safe solution for Romanian Energy” – Monitorul de Petrol și Gaze, no. 8 and no. 10 / 2016. 3. V. Vaida Strategia Energetică a României. Orientări strategice pe termen mediu și lung, Editura Agir și Editura SIER, București 2015. 4. D. Fodor, T. Trotea Cărbunele în strategia energetică a României – Monitorul de Petrol și Gaze nr.1 din 2017 5. D. Fodor, M. Georgescu Soluții de salvare a mineritului din Valea Jiului – Revista Minelor nr. 4 din 2016.

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SURFACE SUBSIDENCE PROGNOSIS USING THE INFLUENCE FUNCTION METHOD IN THE CASE OF LIVEZENI MINE Dacian-Paul MARIAN*, Ilie ONICA**, Ramona-Rafila MARIAN***, Dacian-Andrei FLOAREA***

Livezeni Mine is located in the eastern part of the mining basin of the Jiu Valley (Romania), having as the field of activity the pit coal exploitation. In the area of influence of the underground exploitation of the coal deposits there is also the access road to touristic areas of the Parâng Mountains among other civilian objectives. For the prognosis of the surface deformation as a result of the underground exploitation, the method of influence functions was used in this study. The results obtained are compared to the measurements carried out in the observing station of the surface deformation located on the surface in the area of the studied objective. Keywords: prognosis, influence function, subsidence, horizontal displacement. 1. GENERALITIES The coal basin of Petroșani, under the management of the National Coal Company Petroșani, contains the most important coal deposit in Romania, with a supply of balance of nearly one billion tons. This deposit has been known and extracted since 1788, the time of the AustroHungarian Empire [1]. However, intensive extraction of this deposit began with the

industrialization of Romania after the Second World War, and reaching a capacity of production exceeding 9-10 million tons per year after 1980 [1]. Because of the restructuring of the Romanian industry after 1990 in accordance with the new requirements of the market economy, the production in this basin has reached approximately 3.5 million tonnes per year, of which 0.5 million are derived from the mining field of Livezeni. In this area a number of 18 seams was identified by the geological research works, of which the greatest importance economically is the seam number 3 (48%) and 5 (12%). The object of this study is to analyse the influence of the underground mining of four panels (panel (3-4), panel 5, panel 5A and panel 6) located on seam 3 block VI A, on the road to the tourist areas of the Parâng Mountains. For this study the influence functions method was used. Seam 3 (Fig.1) relating to those panels has been operated in the tilt slices (approx. 2.5 m thick) with mechanized long fronts (SMA P2H mechanical support, combines and armoured personnel carrier 2K52 MY-TR-7) and directing the pressure through total collapse of the rock from the roof [2]. The sizes of the coal-mining excavations resulted through the underground mining in these four panels are summarized in Table 1.

Table 1. The average size of the extracted panels, seam 3, block VI A Number Total extracted Length of the Extent of the Panel of slices thickness, (m) coal face (m) coal face field, (m) Panel (3-4) 4 10 119 346 Panel 5 5 12,5 87 440 Panel 5A 2 5 57 385 Panel 6 1 2,5 137 362 2. GEO-MECHANICAL CHARACTERISATION Since the genesis of the deposit is sedimentary, the most common rocks in the basin are limestone, marl, clay, sandstone and clay shale,

conglomerate, etc., whose strength is between 15 to 16 MPa, and even more than 50-60 MPa [3]. Mainly, the rocks have relatively low stability [3], [7].

* Lect Ph.D eng., University of Petroșani ** Prof. Ph.D eng., University of Petroșani *** Ph.D stud. eng., University of Petroșani

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Fig. 1. Monitoring station of the ground movement and deformation at Livezeni Mine The main factors that contribute to the state of the tension and deformations developed around excavations generated by the underground mining with the collapse of rocks of the coal seams in the Jiu Valley are: the sizes of the underground excavation, the inclination of the deposit, the depth of location of the deposit, the characteristics of the support of face, the speed of advancing front coal face, and the distance from the adjacent coal face and the other extracted seams, the geo-mechanical characteristics of the surrounding rock, etc. [4], [5], [9]. As a result of the observations carried out on the ground surface under the influence of the underground mining, in order to design optimal sizes of the main pillars of safety, the limit angles of subsidence for different mining fields in the Jiu Valley have been established [9], [10]. The limit angle values of influence (

 ,

and  ), depending on the operating depth H (m) for the mining area Livezeni, in accordance with the instructions drawn up by ICPMC Petroșani are expressed by the following relations:

  0,0309  H  56,8   0,0261  H  56,133   0,146  H  51,867

Also, in the same conditions, the average breaking angles recommended by ICPMC are [9]:

 rupere  45  55o ;  rupere  55  60 o ;  rupere  75o [9]. 3. MONITORING OF SURFACE SUBSIDENCE AT LIVEZENI MINE At present, the monitoring of the movement and deformation of the surface under the influence of the underground mining is achieved by means of a monitoring station from the Livezeni Mine is made up of 50 benchmarks. Their layout was carried out along the way which assured the access to the tourist areas of the Parâng Mountains [4], 5. This monitoring station [8] provides information on the movement and deformation of the surface as a result of the underground mining of seam 3, block VI A, the panels (3-4), 5, 5A and 6. Topographical observations have been performed every three months since 2001. Over time, most initial benchmarks that formed the original monitoring station disappeared being replaced with new ones. Due to this, the interpretation of the measurements made on this station is cumbersome and does not provide satisfactory results in terms of the size of the surface degradation in the area. Revista Minelor / Mining Revue - nr. 1 / 2017

The measured subsidence trough (Fig. 2) is a composed trough, resulted from the underground mining of the 4 coal panels. The subsidence trough has an irregular shape (somewhat sinusoidal) due to the fact that the four individual subsidence troughs

(of each extracted panel) intersect, and because the state of the station is located at the edge of the extracted areas (Fig. 1), an area in which the transverse deviations are at maximum.

Fig. 2. Subsidence profile measured in time at Livezeni Mine 4. INFLUENCE FUNCTION METHOD The influence functions methods are based on the prognosis of the subsidence trough with the help of the influence area theory around the point of extraction [4], [5], [10]. These methods can be applied to the extracted areas of different forms, but they are more difficult to calibrate and verify than the profile functions methods. These are methods used to determine the influence exercised at the surface by the partial elements of the extracted area.

Fig. 3. The influence of extracting the base element Q Different forms of influence functions were obtained by several researchers subsidence events including - Bals 1932 Bayer, 1945; Sann 1949 Knothe 1957 Kochamanski 1957 Ehrhardt and Sauer 1961; Brauner 1973; Zich 1993, etc. [5].

ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, PetroĹ&#x;ani, Romania

In the case of this paper, for the surface deformation prognosis due to the underground mining, was applied the influence function method developed by Knothe (also known as KnotheBudryk method). This method is based on Gaussian distribution of the probabilities. In this method, the math function is:

5. THE PROGNOSIS OF SURFACE DEFORMATION AT LIVEZENI MINE By applying the influence functions method in the case of Livezeni mine, for the four extracted panels taken into account and combining the subsidence beds generated by the extraction of each panel, has resulted a common subsidence trough. Its configuration in the studied route (road makes access to tourist areas to the ParĂ˘ng Mountains) is shown in Figure 4. The maximum subsidence expected has a value of 5150mm, a value that exceeds the value measured by in the monitoring station of 1309mm. This difference between the measured and expected subsidence is due to the fact that the predicted subsidence bed is considered to be final, the phenomenon of subsidence is still in the active phase, but also because the initial benchmarks that made up the topographical monitoring station have

been replaced with others (due to modernization works of the road). Similarly, the horizontal displacements of the surface have been obtained on the two directions (X and Y, Fig. 5 and Fig. 6), and the total maximum horizontal displacement (Fig.a7).

The horizontal movement on the axis X, considered approximately transversely on the direction of the road, has a maximum value predicted of 550mm (Fig. 5) and the axis Y, considered somehow on the direction of the road, takes values between -2230mm and +2140mm (Fig. 6).

Fig.4. The subsidence trough obtained using the influence function method

Fig.5. Horizontal displacement after X axis

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Fig.6. Horizontal displacement after Y axis

Fig.7. Total horizontal displacement 6. CONCLUSIONS The influence functions method belongs to the empirical methods group applied for the prognosis of the surface deformation due to underground mining. Unlike the profile functions method, this method can be applied and operated in the case of several extracted areas, or in the case of the extracted areas with difficult configurations. By applying the profile function method in the case of the current paper, an overview on the influence of the extracted areas was obtained (and thus on the access road located in the influence area of the underground mining).

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Therefore, through the interpretation of the results it is expected that after the maximum vertical displacement of the object to be about 5 m, and the maximum longitudinal horizontal displacement to be about 2m. Although the area has a monitoring station, the disappearance of the monitoring benchmarks (and their subsequent replacement with others), this does not provide comprehensive data on the deformation of this objective. The current monitoring station in the case of Livezeni mine is made up of 50 benchmarks, in which are measured every three 3 months, the movement and deformation of the surface as a result

of underground mining af seam 3 with four fully mechanized long fronts by the total collapse of the surrounding rocks, in panels (3-4), 5, 5A and 6. The subsidence trough measured in the station has a very complicated shape, being the result of the underground mining of seam 3 in the four close panels, and the station is located on each side of the four extracted panels (an area in which the transversal displacement is substantial, a maximum displacement of 550mm resulted from the predicted models). Moreover, due to the fact that the monitoring benchmarks are not located on a depth above the freezing level, they are affected by the enlargement of the land during wintertime (which is what is shown in Fig. 2, where the ground enlarges rather than subside at two successive measurements).

6. G. Oncioiu, I. Onica Ground Deformation in the Case of Underground Mining of Thick and Dip Coal Seams in Jiu Valley Basin (Romania), Proceedings of 18th International Conference on Ground Control in Mining, 3-5 August, 1999, Morgantown, WV, USA, 1999.

Bibliografie

9. I. Onica, E. Cozma, D.P. Marian Analysis of the Ground Surface Subsidence in the Jiu Valley Coal Basin by using the Finite Element Method, Proceeding of the 11th International Multidisciplinary Scientific Geo-Conference & EXPO - SGEM 2011, Sofia, Bulgaria.

1. B. Almăşan The Mining of Romanian Mineral Resources Deposits, Volume I, Editura Tehnică, Bucureşti, 1984. 2. Șt. Covaci Underground Mining, Vol.I, Editura Didactică şi Pedagogică, Bucureşti, 1983. 3. C. Hirean Rocks Mechanics, Editura Didactică şi Pedagogică, Bucureşti, 1981. 4. D.P. Marian Surface Stability Analysis as Effect of Underground Mining of the Coal Seams with Gentle and Medium Dip from the Jiu Valley Coal Basin, Ph.D Thesis, Petroşani 2011. 5. D.P. Marian Topographic monitoring and analyse of surface deformation afected by the underground mining, Editura Universitas, Petroşani, 2012

7. I. Onica, E. Cozma, D.P. Marian Ground Surface Deformation Using the Finite Element Method, in Conditions of the Longwall Mining of the Coal Seam No. 3 - Livezeni Mine, Revista Minelor Vol. 17, Nr. 1/2011. 8. I. Onica, E. Cozma, D.P. Marian, N. Ștefan Prognosis of the Maximum Subsidence and Displacement of the Ground Surface in the Jiu Valley Coal Basin, Proceeding of the 14th International Multidisciplinary Scientific Geo-Conference & EXPO SGEM 2014, Vol. III, Sofia, Bulgaria.

10. I. Onica, D.P. Marian Ground surface subsidence as effect of underground mining of the thick coal seams in the Jiu Valley Basin, Archives of Mining Sciences, Vol. 57, nr. 3, Polonia 2012. 11. M. Ortelecan The Study of Ground Surface Displacement Under the Underground Mining of Jiu Valley Coal Deposits – Eastern Zone, Ph.D Thesis, Universitatea din Petroşani, 1997. 12. M. Ortelecan, N. Pop Topographical methods used for the monitoring of surface and buildings behaviour, Academic Press, ClujNapoca, 2005.

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OPERATING THE OIL PRODUCTION FACILITY WITH SOLAR PANELS AND WIND GENERATORS Marius STAN*, Lazăr AVRAM* Sorin AVRAM**, Thair AL SHAMI*** Abstract: In this paper we present an analysis of theoretical concepts very common nowadays, photovoltaic power generators and wind turbines. In addition, we propose an application, a hybrid generator (photovoltaic-wind) to power a progressive cavity pump used for the extraction of petroleum. Key words: photovoltaic systems; wind turbines; power; progressive cavity pump; 1. INTRODUCTION Sun is undoubtedly a vast source of energy. In a single year, it sends to Earth 20,000 times the energy needed by the entire world population. In just three days, the earth receives from the sun enough energy to equal all existing fossil fuel reserves. Solar energy is one of the potential future energy sources to be used permanently replacing conventional energy sources such as coal, oil, natural gas, etc.; however, it can be used today as an alternative to the conventional sources of energy, especially during summer. The second use is currently the most widespread use around the world. Perhaps the most obvious advantage to using the solar energy is that it does not produce environmental pollution, so it is a clean energy source; another advantage of solar energy is that the energy source used is for free. A photovoltaic system (SFV) "converts solar energy directly into electrical energy based on the photovoltaic effect, and brings it to the electrical parameters required by the consumer", [1]. The solar cells can be classified according to several criteria. The most commonly used criterion is the one that classifies cells after the thickness of the material. Here we can make the difference between thick cells and thin cells. Another criterion is the kind of material used, for example, combinations of semiconductor CdTe, GaAs or CuInSe but the most often used is silicon. Silicon cells • Thick layer - Mono crystalline cells (c-Si) with high efficiency - in serial production can reach to over 20% power efficiency; the manufacturing technique is very well developed. However, the manufacturing process is energy intensive, which has a negative influence on the period of recovery (the time needed for the equivalent energy consumed in the manufacturing process to become equal to the amount of energy generated). * Oil and Gas University of Ploiești ** ROMGAZ S.A. Ploiești *** AVISAG S.A. ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

- multicrystalline Cells (mc-Si) - the serial production has already achieved an energy efficiency of over 16%, relatively low energy use in the manufacturing process, and, so far, the best price – performance ratio. • Thin layer - Amorphous silicon solar Cells (a-Si) – represents the largest segment of the market with thin film cells; the energy efficiency of the modules is from 5 to 7%; there are no bottlenecks in supply even at a production of Terra Watts. - Crystalline silicon cells, e.g. microcrystals (μc-Si)

Fig. 1. The working principle of photovoltaic cells (source: solar.promacht.ro), [2] 1 - silicone coating (type N) 2 - photovoltaic cell 3 - sunlight 4 - silicone coating (P) 5 - DC Flow 6 - electric charger Semiconductors based on III-V group elements • GaAs cells – high efficiency, very stable at temperature changes, Semiconductors based on II-VI group elements • Cells with CdTe – use a very efficient CBD technology (deposition of thin layers on a large surface, with controlled pH environment, temperature and concentration of reagent) • CIS, CIGS Cells - CIS stands for Copper-IndiumDiselenide produced in a pilot plant, or CopperIndium Disulfide, and CIGS Copper-IndiumGallium-Diselenide produced in pilot plant. Solar cells based on organic compounds - organic chemistry based technology provides compounds 15

that can allow cheaper manufacture of solar cells. However, they have an impediment that these cells have a low efficiency and a reduced lifetime (max. 5000h). Pigment cells - also known as Grätzel cells, natural pigments used for converting light into electricity; a procedure that is based on the effect of photosynthesis. Usually they are purple. Semiconductor electrolyte cells - cells are very easy to manufacture, but their power and safety of use are limited [1]. Cells based on polymers - now in the research stage only. The total thickness of the photovoltaic cells is approx. 0.3 mm, and its layer thickness is approx. 0.002mm. Usually, above the negative electrode of the photovoltaic cell, there is an anti-reflection coating, aiming to prevent the reflection of solar radiation incident on the cell surface so that "a higher amount of energy can be transferred to the valence electrons of the two semiconductor layers." [8] Photovoltaic cells have as the most usual size 10x10cm but, lately, 15x15cm cells have been used. Besides the photovoltaic generator-cell, a module or photovoltaic panel for efficient use of electricity and other components are necessary. For example, to compensate for the dependence of power generation on the solar radiation, in most cases electrical energy storage means are required or a battery. Its correct functioning implies a load control block. Adapting the PV generator to the consumer’s electrical parameters requires either a DC-DC converter, or a DC-AC one, or both. In some situations the "photovoltaic generator is coupled with alternative resources." All of these components, working together, constitute a system called photovoltaic system. PV systems fall into two main categories: • autonomous systems ("stand-alone"), which supply consumers not connected to the public network adapter. These systems are used in areas without electricity. In principle, "the energy produced by the solar panels is stored in batteries" and the system contains an inverter (DC Converter - AC), 220V home users (Fig. 2). • Nonautonomous systems, or connected to the public network adapter ("Grid - connected") (Fig. 3). These systems are used in areas with electricity. In principle, the energy produced by the solar panels is fed into the national grid and simultaneously used for household applications. How the system is designed may affect its life. The design process "must be carefully reviewed and must take into account all aspects, in order to get the best features" based on available resources and 16

taking into account potential losses from the system to maximize profitability. This can be achieved in various ways, but choosing the best components (a quality inverter can increase production by 2% using the same materials) and the choice of appropriate installation technology are crucial [3].

Fig. 2. A "stand-alone" photovoltaic system [11]

Fig. 3. A "grid-connected" Photovoltaic system.[11] 2. ELECTRICITY WITH PHOTOVOLTAIC SYSTEM Applicability. Power produced by photovoltaic systems is useful in most applications including for motors, pumps, electrical equipment and lighting. The use of photovoltaic systems is not recommended the in water heating systems or for cooking (microwave, toasters can be used due to reduced working time). For these, applications dedicated solar systems are in use (heating habitat with solar systems) (Fig. 4). Shading. Unlike solar heating systems, shading in the case of photovoltaic solar panels can have an important effect in the efficiency of the system. Some solar modules provide partial protection to shading by using a diode between each cell. Angle of installation for solar panels. Because the angle of the sun in the sky varies according to the season it is useful to bring corrections to panel position: + 15 degrees in winter and - 15 degrees in summer. Choosing voltage is determined by the size of the system. For small and medium systems where most consumers are DC (Fig. 4) or, through a

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converter, some consumers are AC (alternating current) the choice is simple - 12 V. Moreover, solar modules and consumers cannot be positioned at a distance one the other due to losses. 24 V systems are for medium and large applications due to the lower losses and to the use of more efficient alternating current (AC) converters. With the increase of efficiency for utilities with alternating current (AC) systems of 24 V and 48 V have several advantages in large applications (connecting batteries).

Fig. 4. Solar system for independent consumer using DC, [13] 1 - photovoltaics 2 - load control 3 - Disconnect 4 - fluorescent light (CC) 5 - TV, radio 6 - deep cycle The controller is the part that determines when the battery is fully charged without allowing overloading; it prevents leakage of energy from the solar cell battery overnight, reduces battery deterioration by a total discharge, and may show the state of the system and offer short circuit protection. Converter. The core component of an environmental system that converts low voltage DC current into high voltage alternating current (AC). The main feature is the efficiency of the device. 3. WIND TURBINES Wind energy is the result of the activity of the Sun and is formed due to uneven heating of the Earth's surface. The movement of air masses is formed due to different temperatures of two points on the Globe, with the direction from the hot to the cold point. Wind as a primary energy source costs nothing. It can also be used decentralized â&#x20AC;&#x201C; it is a good alternative for small localities distant from traditional sources. Starting with the beginning of human civilization, wind energy was used in sailing. It is assumed that the ancient Egyptians went under sail far back as 5,000 years ago. Around 700, in

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Afghanistan vertical rotation axis wind machines were used for grinding the grains. Well-known wind turbines (tower mills with propellers connected to them) ensured the functioning of irrigation systems on the island of Crete in the Mediterranean. Mills for grinding grain, which run on wind, are one of the greatest performances of Middle Ages. In the 14th century, the Dutch improved the windmills model which was spread across the Middle East and began the widespread use of wind turbines for grinding beans. In 1854, in the US, a water pump that operated on wind energy was developed. The construction of this pump model resembled windmills, but it had more blades (arms) and a wind vane to determine wind direction [5]. By 1940, in the US, over 6 million installations of this type were used for pumping water and producing electricity. It is considered a prerequisite for conquering the Wild West because of the potential water supply for livestock farms. But mid-twentieth century brings to an end the widespread use of wind energy, exchanging it for its modern counterpart energy source - oil. The wind energy interest reappeared after several oil crises experienced by mankind for decades. This happened in the early 70s, due to the rapid increase in oil prices when the US had adopted several programs to encourage the revaluation of wind energy. In California, at the end of 1984, 8469 wind turbines were already in operation. The total capacity of these units was approximately 550 MW. They were built in places with strong winds, grouped into so-called wind farms. Wind turbines for producing electricity can be used individually or in groups, called wind farms. Wind farms, which are now fully automated, ensure, for example, 1% of California's electricity needs, i.e. 280 000 homes. However, wind turbines had some problems: large changes in wind speed causing variations in electric current generation and sometimes damaging the transmission systems; after a while, rotor blades collected foreign substances, dust etc., which reduced their efficiency [4]. To measure wind speed and temperature a Data Logger can be used. It is an electronic device that records data over time and, correlating with the location of sensors and transducers in a given location, it processes the data using a programmable logic microprocessor and displays information on the display screen or transmits it to a PC. The Data Logger used for acquisition of slowly varying data, with a maximum acquisition speed of 1Hz are not considered real-time data acquisition devices. Data Logger processed data is stored on a flash memory or EEPROM. The main

applications of this system are recording wind speed, temperature and humidity. The main blocks and Data Logger system logic for measuring wind speed and data processing using the Hyper Ware software programming are shown in Figure 5. Fig. 7. The solar-wind hybrid system

Fig. 5. Wind speed measurement A wind system, figure 6, in terms of energy, converts kinetic energy of wind into electricity.

Fig. 6. Wind System Components 4. UNCONVENTIONAL POWERING WITH SOLAR PANNELS AND WIND GENERATOR FOR A PCP OIL EXTRACTION SYSTEM Sizing a renewable source of energy to power 10 kW One of the most common applications of alternative energy is now the power supply for a holiday home or cottage, located in an area without access to the public, but in view of the developments in technology, hybrid systems may be successfully used in industrial fields. To power a progressive cavity pump we can decide for producing power using photovoltaic panels or wind generators. Their combined use is always possible and recommended due to the purpose of use and relatively high power needed. To provide all these consumers with electricity, a solar panels system must produce all the electricity required. These consumers need about 8 KWh per day for 7 days a week or we can consider an average consumption of 270 kWh / month. The system has an autonomy of two days, which means it can provide the energy needed for 2 days even without any application of energy from the photovoltaic solar panels and the wind turbine. 18

For this application we will need the following components: • photovoltaic solar panels; • a wind turbine; • group of batteries (rechargeable batteries) to 12 V; • battery charge regulator; • inverter DC (12V) - AC (220V); • energy saving lamps DC; • equipment and connectors for assemblies. To cover the consumption we will need: • 84 x 250W photovoltaic panels (21 KW installed capacity); • 1 x 10 KW Wind Turbine KIT; • Charge 4 x Vario Track 80A Controllers; • 3 x XTM 3500-48V inverter Studer; • 1 x RCC-02 communication interface; • 24 x Hoppecke 12V deep cycle battery with 4700Ah; • 1 x 10kW SMA inverter On grid Where the electricity grid is near the extraction well, a hybrid system can be connected to the network and, once batteries will be charged at 100%, they will inject the excess of energy into the national grid; this energy could be used at a later date due to a bidirectional meter. If the national electricity network is at a greater distance of 300-400 m from the well location, alternative energy supply is the most cost-efficient solution. To achieve a hybrid system, shown above, it is not necessary to purchase an ON GRID 10 KW inverter but, for safety (in case of failure of the hybrid system), a diesel generator with a capacity of 10 KW can be installed. 5. OPERATING THE PCP PUMP WITH UNCONVENTIONAL RENEWABLE ENERGY The basic configuration of the surface driven PCP system illustrated in Figure 8 is the most common, although the downhole pumps are both hydraulic, electric and hybrid CFP, various other systems are also available [10]. The PCP well pump is a positive displacement pump composed of two parts: a steel "impeller" screw and a "stator” composed of rugged steel cylinder with a sleeve of elastomer adapted properly to the configuration of the rotor. The stator is usually placed in the well, at Revista Minelor / Mining Revue - nr. 1 / 2017

the bottom of the extraction column, while the rotor is connected to the bottom of the rod. Rotation of the rod by means of a drive system at the surface causes the rotor to rotate within a fixed stator, creating the pumping action required to bring fluids to the surface.

In a single lobe pump, the rotor is of circular cross-section (with a small diameter, d), while the stator cavity has a semi-elliptical geometry. Another important parameter is the geometric eccentricity of the pump (s) which is equal to the distance between the axes of the major and minor diameters of the rotor. The distance between the stator axis and the rotor axis of maximum diameter is also equal to the eccentricity.

Fig. 9. The geometrical characteristics of a pump with hp with a single lobe, [9], [13].

Fig. 8 Typical configuration of a system of progressive cavity pumping (PCP) PC downhole pump Cavity pumps can be single-rotor helical gear pumps all in the category of positive displacement pumps. The rotor is the "internal gear" and the stator is called the "external step" of the pump. The stator has always an extra "tooth" or "lobe" than the rotor. Cavity pumps that are found currently on the market fall into two different categories, according to their geometric design: single lobe pumps and multilobe pumps. Currently, the vast majority (that is, somewhere in> 97%) of cavity pumps that are used in drilling wells are with a single lobe and, therefore, they are the most effective solution to be powered by a hybrid system; [7]. The geometric cavitations pump with a single lobe is illustrated in Fig. 9. In fig. 10, we presented the single helical shape of the rotor and the helical geometry corresponding to the stator. Note that the stator step length (Ls) is twice the rotor step length for pumps with a single lobe. With the pairing of the rotor and the stator in a CP pump with a single lobe, two parallel cavities are formed (at 180 Â° with respect to one another with an out of phase rotor step) which rotates around the outside of the rotor along the length of the pump, each cavity having a length equal to the stator step length. Note that the parallel recesses are offset lengthwise with the end of a cavity on one side of the rotor corresponding to the maximum cross section on the opposite side of the cavity, [8].

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The rotor creates a seal with the stator elastomer on both sides of the opening, a half-elliptic and a semi-circular stator seal over the opening ends of the corresponding longitudinal cavities. Fluid cavities are formed by remaining open areas between the rotor and stator, each cross section. Fig. 10 shows a sectional view of a single lobe pump with CP rotors and stators and different geometry in several models of pumps. Renewable energy supply The 10KW monophase hybrid system combines the photovoltaic solar technology with the obtaining of electricity using photovoltaic electric panels and wind turbines, producing energy from wind. These single-phase PV and wind hybrid systems offer stable electricity supply to all consumers, despite the weather conditions. The advantage of hybrid systems is that photovoltaic panels operate in parallel with wind and consumed electricity is stored in the solar system batteries. The system is sustainable and efficient the initial investment being covered in a short time.

Fig. 10. Sections rotor / stators from different pump models

The 10KW monophase hybrid system provides a 40 kWh average daily production each year from solar panels; electric batteries can store 21.6 kWh and wind can produce 600Wh when wind speed is 11 m/s. The powering of progressive cavity pumps from renewable sources will be achieved as follows: The Photovoltaic generator and the windmill convert the energy received from the sun and wind in DC electricity using the photovoltaic effect and rotational movement of the turbine blades. The generators will produce voltage and DC. However, the motor of the cavity pump requires AC power. The photovoltaic system must therefore contain a converter DC-AC i.e. an inverter. Besides the converting function, an inverter performs many other functions being the most intelligent component of a hybrid system. The charging regulators (or controllers) will store the energy generated using photovoltaic cells and wind in batteries to prolong their life (by avoiding excessive discharge or overcharge). The voltage of the DC electricity "produced by the generator in many cases does not correspond to the necessary voltage for proper functioning of the consumer." To "transform" continuous voltage to an appropriate level, we use electronic blocks called CC converters. They can be found as distinct blocks, but more often appear in the composition of inverters or of other blocks which adjust the load to the generator (called MPPT - Maximum Power Point Tracker). If the hybrid system is connected to the national electricity grid and electricity production is higher than necessary for the function of the cavity pump engine and the batteries are charged, the system will inject the excess of energy into the national grid and this energy could be used at a later date due to a bidirectional meter [11]. If connecting to the national grid is not possible, alternative energy supply is the most costefficient solution. To achieve the hybrid system described above, it is not necessary to purchase an ON GRID 10 KW inverter, but, for safety (in case of failure of the hybrid system [12]) a diesel generator with a capacity of 10 KW can be installed.

Small wind turbines play an important role in off-grid projects in locations where winds ensure enough energy supply, since alternatives such as diesel generators have a high cost of fuel when used as a continuous power supply. This is also applicable to installations connected to the power grid, despite the fact that their production price per kWh is usually higher than in the case of large wind turbines. Photovoltaic solar panels and wind generators (hybrid systems) also produce electricity. The advantages of using solar panels and wind generators is represented primarily by the possibility of providing electricity in remote locations without access to the main electricity supply (the national grid). Such a system is easy to install, requires no special knowledge in the field of energy and the maintenance for the panels is easy (it only requires cleaning the impurities that attach to their surface). The average use of panels and wind turbines is 20-25 years, the only part that needs more attention and whose lifespan is shorter for the isolated systems are the batteries. Another considerable advantage of these systems is that they can expand in case of additional electrical consumers. Disadvantages include: high cost of investment, geographical location on latitudes which lower the efficiency of the systems and the danger of destruction for panels because of weathering; increase disaster risks - panels and turbines are exposed to weather conditions.

6. CONCLUSIONS Depending on the energy provided, solar panels can be divided into photovoltaic panels that generate energy and solar thermal panels, which convert light energy into thermal energy. Solar panels are one of the most popular alternative energy sources used to power private and industrial consumers. Solar technologies use the sun's energy to produce heat, light, hot water and even air conditioning for residential and industrial areas.

3. Drăgan V. Renewable energies and their use, Editura Atlas Press, Bucureşti, 2009

Acknowledgment I extend my thanks to OIL FIELD SERVICES SRL company CDI for permanent collaboration with our university. REFERENCES 1. Ardelean Z. Solar Collectors, Editura Ştiinţifică şi Enciclopedică, Bucureşti, 1988 2. Burghiu V. Clean non-conventional energies - wind, sun, geothermics, biomass, tide, waves - lithographic course, USAMV, Bucureşti, 1998.

4. Florescu Gh. The energy sources’ adventure, Editura Albatros, Bucureşti, 1981 5. Ghergheleş V. The Energy of the future, Editura Mediamira, ClujNapoca, 2006

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6. Goetzberger A. Photovoltaic Solar Energy Generation, Editura Springer, Berlin, 2009

9. Stoenescu G. Mechanic, Thermodynamic, Electricity and Magnetism, Editura Universitaria, Craiova, 2001

7. Maghiar T. New Sources of energy, Editura Keysys, Oradea, 1995.

10. Temessl A. Design and construction of solar installations – Informative Guide, Editura MAST, Bucureşti, 2008

8. Silvestre S. Modeling Photovoltaic System Using Pspice, Editura Wiley, London, 2010

11. *** - www.panosolare.com 12. *** - www.pvcert.gr 13. *** - http://petrowiki.org

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DESIGN OF ZAM 1 TUNNEL CONCEPTUAL, TECHNOLOGICAL AND STRUCTURAL ELEMENTS Doru ZDRENGHEA*, Corina CHIOTAN** Abstract: The paper presents Zam 1 tunnel located on local variant of Curtici - Simeria railway executed for the rehabilitation of the line for trains with a maximum circulation for passenger trains speed of 160 km/h and 120 km/h for freight trains. The tunnel is designed for double track line and has a length of 610m. The tunnel crosses rock layers on entire length (altered basalt and altered limestone) so the NATM technology has been adopted. The paper presents the types of sections considered, execution technology and the method for structural calculation and validating and the verification of these. Key words: tunnel, portal, shotcrete, anchors 1. Main characteristics of the project and construction Tunnel 1 (Zam 1) is located between km 523+ 757 and km 524+ 367 (L = 610 m), on a section where Curtici - Simeria railway alignment has been modified, between the stations Campuri Surduc and Ilteu. This modification has been done in order to increase the circulation speed of the passenger trains to160 km/h for trains and the circulation speed for freight trains to 120 km/h. In the same variant are located three tunnels (Tunnel 0 having the length of L = 340 m, Zam 2 having the length of L = 227m and tunnel 3 with a length of 603m). Tunnel Zam 1 is located on the left bank of the Mures river, in an area with both forested (the first part of the route) and deforested slopes (the latest part), with a difference between the rail level and riverbed of approx. 30m-40m. In plan, the tunnel has a curve with a radius of 1500 m. In longitudinal profile, slope of tunnel is 3 0/00 over the entire length. Maximum coverage of the tunnel is of approx. 46 m. For safety, there have been placed 24 niches at min 25m interval symmetrically located on both sides. Longitudinally, were placed 24 niches were placed at min. 25m symmetrically on both sides. 1.1. Geological, geotechnical and geomechanical conditions From the geomorphologic pont of view the studied area is located in Mureş river corridor, passageway that separates the Metaliferi Mountains

from Poiana Rusca Mountains, both being parts of the Western Carpathians. Mureş corridor is formed during the Neogene by dipping formations older along fracture systems and is characterized by low-lying, relatively uniform slopes and the topography is less rugged and has a character of terraced hills towards north and terraced towards south. Based on data from geotechnical and geophysical investigations, one can appreciate that tunnel Zam 1 crosses the following formations:  Layer I: represents the topsoil and deluvial layer and it is characterized by a thickness of 0.3 to 0.9 m (average thickness = 0.53 m);  Layer II consisting of deluvial rock fragments and heavily damaged and heavily cracked (clay material clogged), characterized by a thickness of the 1,2 - 6,7 m;  Layer III is represented by the basaltic rock core with alternating black shale clays, cracked and damaged, characterized by a thickness of 8.3 to 44.9m;  Layer IV bedrock: compact (basalt), slightly cracked and weathered, extends to an average depth of 21.47 m. 1.2. Tunnel cross sections, lining systems, the construction method Inner section of the tunnel is established to ensure the clearing for both the rolling material and pantograph and catenary according to documents UIC, STAS 4392-84 Railway clearance and TSI

Fig. 1. Profil longitudinal tunel Zam 1 * drd.ing. Universitatea Tehnică de Construcții București ** șef lucr.dr.ing. Universitatea Tehnică de Construcții București 22

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2008/163 - Safety in Railway Tunnels. The inner section is circular with a radius of 5.8m, for double railway with lines spacing of 4.2m, with a height from NST of 7.87m, the distance between the railway axis and the banchine is of 2.2m and the banchine has 1.2m. The lining has two layers, one exterior of 30cm thickness and one interior of 40cm thickness, with intermediate waterproofing from PVC and geotextile, mounted on the entire section. Based on geological and geotechnical information, resulting from drillings and from geophysical investigations (geotechnical and seismic), the tunnel crosses two soil types.

In accordance with the two types of predicted soil types, two outer lining sections are being proposed: Section I consists of a primary support (outer lining), which consists of: metal form support of GI 100, concreted anchors with the length of 3m placed at 2m in longitudinal section and 2.6m in transverse section and incline anchors (anchors with an inclination of 14˚, having 3.5m in length, at 50 cm in cross section and 2m in longitudinal section) 20cm thick shot concrete, intermediate waterproofing on the vault and straight legs. The final inner lining made of concrete has a thickness of 40cm, and the lower raft foundation is made of a concrete slab of 70cm.

Fig. 2. Type 1 Cross-section

Fig. 3. Type 2 Cross-section Section II consists of a outer primary support made by concreted anchors with the length of 3m placed at 2m in transverse section and at 3.4m in longitudinal section and 10cm thick shot concrete; intermediate waterproofing on the vault and straight legs; the final inner lining made by reinforced concrete 40cm thick, with the raft foundation made of a concrete slab of 70cm. The entrance and the exit portal have the same configuration. ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

Portals are made of a special ring, cut at a 45° at the upper part and have a thickness of 40 cm; the lower part has a length of 9.70m and the upper part has a length of 5.85m; the portal exceeds the initial excavations. The ring is similar to the inner lining in terms of thickness and composition, with waterproofing at the upper side and protection of reinforced concrete with a wire mesh.

Fig. 4. Exit portal -View plan

Fig. 5. Exit portal - Longitudinal section

The initial excavation is 5:1 on the rock zone and 3:1 on the deluvial zone, with a horizontal step between them, where a ditch is placed to collect and evacuate the water. The excavated rock surface is protected with shot concrete of 25cm thickness and the rock is strengthened with concrete anchors with diameter of 25 cm and length of 3.0m and the deluvial area is supported by anchors with variable lengths, from 2.00m up to 8.00m, and reinforced concrete elements.

The method has several important advantages, namely: - the possibility of adapting technology and the type of section, during the execution, depending on the nature of the soil encountered; - the possibility of excavating the whole section or two-stage excavation, the cap and the central core of the tunnel, depending on the nature of the ground encountered, thus leading to a higher productivity and creating an easy opportunity to transport materials; - the possibility of mechanizing all operations and hence achievement of a high execution speed. PHASE 1. The excavation The excavation is executed with explosives in hard and very hard rocks. This technology requires execution of a number of blast holes in the front surface of a certain length and loaded with a certain amount of explosive, which constitute a shooting scheme. PHASE 2. Mounting the anchorages The holes are drilled for anchors with the punching machine with multiple arms of Jumbo type. The anchors are inserted and concreted. The nets and placed and mounted on small plates The rock layers tightened with the help of the anchors forms a block that can resist in good conditions to the pressures of the massive.

2. Execution technology The New Austrian Method (NATM) for hard rocks and The New Austrian Method adapted for weak rock with umbrella pipes are the chosen methods for the execution of these tunnel. The main idea of this method is that the rock around the excavated hole, can be turned into a supporting element (ring bearing rock), with the help a supporting system constructed in due time. NATM concept provides a composed support, consisting of: - The primary support is made of the rock mass (main component), eventually strengthened with anchors and the actual support applied on the exposed surface of the rock mass (secondary component) made by shot concreted lining, eventually, strengthened with metal form or arches; - Secondary support consists of the inner lining, made of reinforced concrete.

Fig. 6. Phase 2 24

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PHASE 3. Constructing the outer lining made from shot concrete. Shot concrete has a constant thickness of 20 cm along the whole length of the section. The outer lining is made of shot concrete C25/30 class. On them, there are mounted wire Buzau type nets with a diameter of 6 mm, 80-100 mm mesh following the covering layers of 5 cm. The shot concrete is applied in successive layers, of 3 cm thickness.

PHASE 4. Excavation of central core Excavation of the central core is made with pick-hammer or explosives and the dumpers are loaded by using the excavator. PHASE 5. Mounting anchors on the straight leg zone. The mounting of anchors on the straight leg zone is done similarly as in Phase 2, with the same machine with multiple arms of Jumbo type.

Fig. 7. Phase 5 PHASE 6. Shot concreting on the straight leg zone. Operation is identical to that in Phase 3. PHASE 7. Excavation of raft foundation with the pick- hammer on half-section. To ensure the works flow, the raft foundation is half excavated, ensuring the works flow with a mobile bridge. The mobile bridge has wheels and joints so that in the next phase it can be placed under that excavated half. The excavation is done with pick-hammer and it is made along sections of 8m length. PHASE 8. Concreting of the raft foundation. After the whole raft is excavated, it is going to be concreted. Concreting is done on sections of 8m length under a mobile bridge. Concrete is delivered with the concrete mixer and poured with a pump. PHASE 9. Installing of waterproofing. After making the first outside lining, the execution of the waterproofing layer follows. On the inner surface of the outer lining, a 2mm thick waterproofing plaster is made. The waterproofing consists of bituminous sheets which are fixed to the outer lining soffit. For lying the waterproofing, a mobile metal scaffolding is used. PHASE 10. Concreting of the inner lining. For this, the steel formwork is fixed, having also a vibrating device, the lining is executed as rings of 10 m length. At the joints, double asphalted sheets are fixed. The concrete is poured with powerful ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, PetroĹ&#x;ani, Romania

pumps. After the concrete is hardened, the steel formwork is relocated to another ring. Between the insulation and the inner lining of the tunnel at the top of the cap some holes are formed and they have to be filled by injection. 3. Structural design and dimensioning of the sections of the proposed To validate and verify the proposed type of sections, numerical calculations are performed by using the finite element computation program, Plaxis 2D. The model adopted for the type I is a computational model on the execution phases, twodimensional, with an area of 55m high and 64m wide, with a coverage of 11.00m. The model adopted for type II is a computational model on the execution phases, twodimensional, with an area of 84m high and 64m wide, with coverage of 33.00m. The soil is modelled with triangular elements, the outer lining and inner lining with slab â&#x20AC;&#x201C;type elements and anchors with bar- type elements. Ground characteristics considered tabulated below are affected with partial safety coefficients according to Eurocode.

Table 1 Ground characteristics Section Type I γ c Φ Ground E (kN/m2) 3 2 (kN/m ) (kN/m ) (˚) Sand 18 51 19 1.31E+04 Clayey (20) (32) (15) (1.19E+04) Alterated 27.5 4000 25 1.30E+06 Basalt (30) (2500) (19) (1.18E+06) 32 (35)

Basalt

16000 (10000)

35 (27)

1.87E+07 (1.70E+07)

Table 2 Ground characteristics Section Type II γ c Φ Ground E (kN/m2) (kN/m3) (kN/m2) (˚) 20 31 19 1.60E+04 Silty clay (22) (19) (15) (1.45E+04) Cracked 23 3000 25 1.50E+06 limestone (25) (1875) (19) (1.36E+06) 28 10000 35 1.87E+07 Limestone (31) (6250) (27) (1.70E+07)

ν 0.3 0.2 0.2

ν 0.3 0.25 0.25

Table 3 Ribbs characteristics Element

Eechiv. (kN/m3)

EA (kN/m)

EI (kNm2/m)

Cintru HEB100

2.1x108

5.460x105

9.45x102

0.2

Secţiune Tip I

Table 4 Anchors characteristics

Section

Anchors concreted

EA (kN/m)

Type I and II

Φ32

16.89x104

Table 5 Characteristics of shot concrete for external lining Section

Shot concrete

E (kN/m3)

EA (kN/m)

EI (kNm2/m)

Type I

20cm

3.2x107

6.4x106

2.133x104

0.2

Type II

10cm

3.2x107

3.2x106

2.667x103

0.2

Tabel 6 Characteristics of reinforced concrete for internal lining

Section

Reinforced concrete

E (kN/m3)

EA (kN/m)

EI (kNm2/m)

Type I and II

40cm

3.2x107

1.28x107

1.707x105

0.2

The model of soil behaviour is the MohrCoulomb model. Design software allows the simulation advancing front so there are considered 5 phases of advancement, 1m each phase.

The phases considered are: - excavation of the crown, installing of anchors, fixing the metal form, shot concreting; - excavation on the straight legs zone and raft foundations - concreting of the raft foundations and inner lining.

Revista Minelor / Mining Revue - nr. 1 / 2017

Fig. 8 The geometry of structure (Section type I)

Fig. 10 Displacements diagram (type I)

Fig. 12 Axial forces (type I)

Fig. 14 Bending moments diagram (type I)

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Fig. 9 The geometry of structure (Section type I)

Fig. 11 Displacements diagram (type II)

Fig. 13 Axial forces (type II)

Fig. 15 Bending moments diagram (type II)

Determination of the stresses required for the reinforcement dimensioning of the inner lining is designed considering that the initial support system is affected in time, while the inner lining becomes the main supporting element, overtaking the permanent loads and the earthquakes. The resulted sectional stresses have led to a constructive reinforcement. In Figures 10 and 11 are diagrams for the displacements of the sections of type I or II. Figures 12 and 13 show the diagrams for the axial forces of the two sections, and Figures 14 and 15 show the moment diagrams.

4. Conclusions Zam 1 tunnel is the only one of the four existing tunnels on alternative route, which is realised entirety with NATM.

The type of rock which is traversed by the tunnel has imposed two types of sections: type I on 160m and type II on 430m. To compensate the low initial geological investigations, there are provided geological charting of the rocks encountered at every step and trough evaluation of their class it is appreciated if it is necessary to adapt the initial supporting elements. REFERENCES 1. PÖYRY INFRA GMBH Rehabilitation of the Railway Line Border – Curtici Simeria, Component Part of the IV Coridor Pan European for the Trains Circulation with Maximum Speed of 160 km/h section 2c: km 614 – Gurasada. 2. Plaxis B.V. PLAXIS 3D Tunnel Version 2.4, Finite Element Code for Soil and Rock Analysis

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IMPLEMENTATION OF SUSTAINABLE PRACTICES IN THE LIGNITE OPEN PIT ROȘIA DE JIU Izabela-Maria NYARI (APOSTU)*, Maria LAZĂR**, Florin FAUR*** Abstract: Exploitation of lignite in Rosia de Jiu open pit can be included in the broad concept of sustainable development through the development and integration of practices that lead to minimizing the environmental impact of mining operations. In this paper are analyzed solutions such as: rational exploitation of the deposit, reducing water and energy consumption, reducing the amount of affected land, preventing environmental pollution and ensuring the rehabilitation and reuse of degraded land. Thus, the land affected by mining can be reused for the development of sustainable activities in order to obtain the best results in terms of environment, community and economy. Key words: environment; land rehabilitation; land reuse; open pit; sustainability 1. Introduction Rosia Jiu open pit, through its location in the region, the morphology of the terrain, the size of the mining area, the development of mining works, large volumes of industrial reserves, difficult geomining and hydrogeological conditions, relatively high reports between overburden and lignite, represents a base study for analyzing operating practices and reusability of the land after the closure of mining activities in the context of sustainability. In Rosia Jiu open pit, the first mining works were started in 1973. After more than four decades of exploitation there were extracted over 100 millions t and in 2015 the available reserves were estimated at 21.5 million t. Mining can become sustainable through the development and integration of practices that lead to minimizing the environmental impact of mining operations. These practices include measures to reduce consumption of water and energy, the amount of land affected, prevention of environmental pollution and measures for closure and rehabilitation of the area. [2] 2. Implementation of sustainable practices throughout the lifecycle of the open pit Since mining activity in Roșia de Jiu open pit is viable for another decade, it requires the implementation of sustainable practices in relation to the exploitation of the resource available, to be effective, primarily in terms of environmental protection, health and safety of population, but also economically. 2.1 Rational and total exploitation of the lignite deposit Complete extraction of lignite reserves and the quality of the extracted coal, are priority issues concerning the rational exploitation of deposits. In Ph.D stud.eng., University of Petroșani Prof. Ph.D eng., University of Petroșani *** Assist. Ph.D eng., University of Petroșani ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, Petroşani, Romania

these circumstances, recovery of coal from the final slopes of the pit and from thin layers is in question. In the first case, the method of extraction with Auger-Mining type drills can be applied. It consists in drilling of large diameter executed in the definitive slopes of the open pit, allowing recovery of coal at the rate of up to 60%, reserves which, under current operating conditions, remains untapped, representing also a financial loss. [1] Coal mining from the final slopes of the open pit is conducted after sizing the drilling holes and security pillars, very important for the stability of the slope. After extracting the coal, the remaining holes in the slopes will be filled with sterile material from waste dumps. In the second case, it is recommended the use of surface combines, which, due to the configuration of the extraction system have a higher degree of selectivity than conventional extraction machinery (bucketwheel, mechanic shovel, backhoe excavators etc.). By using surface combines, layers with small and very small thickness can be extracted selectively without lowering productivity. The extracted material is loaded and transported by trucks. [3] The use of surface combines, in particular for the extraction of thin layers, has two important advantages: due to substantially reducing operating losses, the recovery of reserves is increased by 25%; separate extraction of sterile insertions with small thickness considerably improves the quality of extracted coal, leading, among other things, to a reduction in processing costs. The technique of extracting coal by milling gives the material a particle size less than 150 mm, which corresponds to the requirements imposed by transport on conveyor belts and requirements imposed by power plants.

Other advantages of surface combines, in terms of beneficiaries include: creating a clean working surface; the possibility of depositing directly the sterile derived from insertions; ability to use the equipment not only for extraction but also as auxiliary equipment. 2.2 Implementation of water spraying devices mounted on bucketwheel excavators Following the operations needed to extract the resource, results large amounts of dust that lead to degradation of air quality. This in turn leads to increased risk of illness to employees and local communities situated at relatively small distances from Rosia open pit (Farcasesti MoĹ&#x;neni village at about 250 m, Rosia village and residential area of Rovinari town at about 700 m). Splashing water on sterile materials and lignite, manipulated in the open pit, from excavation to deposition, aims to reduce the amount

of dust and particulate matter from air, by maintaining a sufficient humidity of materials that do not allow to be driven by wind. [6] The method consists in implementing sprayers mounted on bucket wheel excavators, dumping machines (spreaders), loaders and on conveyors. The advantage of this system is represented by the reduction of the amount of dust and particulate maters in the atmosphere, with the possibility of using poor quality water. The costs to implement this system in Rosia de Jiu open pit are relatively low and the benefits are considerable. 2.3 Restoration of land while exploiting In order to recover and reuse lands affected by mining from the operating stage, restoration of land is recommended to be carried out while exploiting (fig. 1), by the immediate start of reconstruction and rehabilitation processes of the areas freed from their technological tasks. [5]

Fig. 1 Restoration of land while exploiting This practice presents important advantages, such as reducing the period of rehabilitation of the area of land affected after closure of the open pit, reducing the degree of pollution of the environment, gradual reintegration of land in the adjacent landscape and the possibility to reuse of the rehabilitated land for other purposes. 2.4 Reuse of waste material Waste rock resulting from the extraction of lignite in Rosia de Jiu open pit, are made of clay, sand and gravel and they contain no hazardous substances. The waste material can be used as filler in the construction of highways and the rough fraction can be used as embankment to protect riverbanks, to ensure the stability of natural and artificial slopes and reinforce dams. The advantages are represented by the reduction the amount of waste material deposited and thus the surfaces of natural lands occupied, and by the reduction of the amount of construction materials exploited.

3. Implementing sustainable practices after cessation of mining activities Lignite resources from Rosia de Jiu open pit are sufficient only for the next 10 years. Given the fact that the local economy will be affected by its closure, is essential to recover the affected land and return it to the natural or economic circuit. In this regard, the paper analyzed three land reuse solutions that can contribute to sustainable development of the region (that can be adapted for other similar regions): - reconstruction and ecological rehabilitation of degraded land; - construction of a photovoltaic park; - implementing a system for collecting and recycling municipal waste. By 2015, the open pit occupies 392.3 ha, the interior dump 573 ha, and the exterior dump 493 ha. It was chosen for the photovoltaic park to be constructed on the interior dump and in the open pit, while the remaining premises in the mining perimeter to serve for collection and recycling of municipal waste. Since the exterior waste dump is already restored (forestry plantation), it is recommended the maintenance and monitoring of the works. Revista Minelor / Mining Revue - nr. 1 / 2017

3.1 Reconstruction and ecological rehabilitation of degraded land After exploitation works, the land must be released from its technological tasks and of the decommissioned constructions at risk of collapse or that can not be used in future economic activities. Before the land is reused, its rehabilitation and recovery is necessary, through a complex process that involves insurance of physical, chemical and biological stability of the degraded land, reshaping the land in order to increase the stability of the pit and waste dumps slopes and its reintegration in the adjacent landscape, deposition of a layer of topsoil and its amendment in order to improve soil quality and, not least, revegetation of the land depending on the type of reuse. Recovery and rehabilitation of land in the mining area of Rosia de Jiu open pit, for the development of a photovoltaic park, does not require special environmental conditions. There are needed stabilization, leveling, reshaping and terracing works to reduce the inclination of the open pitâ&#x20AC;&#x2122;s and dumpâ&#x20AC;&#x2122;s slopes, so that rolling or collapse of rocks are not be triggered, and at the same time to ensure the location and optimal operation of photovoltaic panels. Minimal recovery

processes are sufficient, which involves improving environmental quality, so that adjacent ecosystems and local communities are not affected. Taking into account the proposals for future activities, it is recommended grassing of the land with an important role in erosion control and soil binding. However, in marginal areas, it is recommended the plantation of vegetation curtains for land protection against wind erosion, land stabilization and improvement of water regime. Revegetation is made after a layer of topsoil is deposited and amended order to improve quality and ensure optimal conditions for maintaining the vegetation. To restore the hydrostatic level of groundwater in adjacent areas and to protect the remaining hole in which the photovoltaic park will be constructed it is suggested the construction of waterproof screens around the mining perimeter (fig. 2). Recovery of the hydrostatic level by natural means may take a long time, but there is the possibility of accelerating this process by injecting water behind the impermeable screens, through a reverse dewatering process. [8]

Fig. 2. Restoration of hydrostatic level of groundwater using waterproof screens After the land is recovered, it requires maintenance and its necessary to monitor the environmental components, to determine and eliminate potential sources of pollution and their negative impacts. 3.2 Construction of a photovoltaic park Lignite exploitation was the basis for production of electricity, at national level, by its integration in the National Energy System, for supply of industry and population. With the closure of Rosia de Jiu open pit, but also from other lignite open pits in the country which have reserves available for the next 20-40 years (as a result of the mining sector restructuring process), reduces the amount of lignite extracted and thus the amount of electricity produced from it. ISSN-L 1220-2053 / ISSN 2247-8590 Universitas Publishing House, PetroĹ&#x;ani, Romania

Solar energy is the energy produced directly by the transfer of light energy radiated by the Sun and can be used both for domestic consumption to generate electricity or to heat the air inside buildings and nationally, through the occupation of large areas of land in order to supply the National Energy System. Solar panels generate electricity and, at the same time they store energy in batteries to be used when solar energy is inefficient. Given that solar potential in Romania has remarkable values and that in most developed countries in Europe (even in those with solar potential lower than in Romania) electricity production based on energy of sunlight is successful, it can be stated that the development of a large photovoltaic park in our country, would be a major step towards sustainability. In this regard, an 31

important aspect is the represented by the insurance of environmental and community protection. For the case study of Rosia de Jiu open pit, it can be considered as an advantage the possibility of occupying a large area of land, approximately 1,000 hectares (considering the space available currently and extension until closure), given that one of the largest solar parks in Romania occupies an area of approximately 150 ha (near Sebiş, Arad county), and the largest photovoltaic park in the world, located in the Mojave desert, California, occupies an area of 1600 ha. Each element of the complex that constitutes the photovoltaic park has a well defined role: - photovoltaic panels capture solar energy; - energy is taken up by a junction box from a series of panels; - the generator connection box takes energy from more junction boxes; - energy is transformed from DC to AC by a triphasic inverter; - through an electrical station the energy is transmitted to the National Energy System. [7]

The construction of the photovoltaic park involves the following: construction of access roads for maintenance processes and enclosure fences, installation of steel structures, cables and panels, mounting connecting stations and transforming stations with inverters. In 2011, the company BoDean operating in quarrying, was the first company in the world that functioned entirely on electricity produced by its own system of photovoltaic panels mounted on the closed and recovered steps of the open pit. [9] Starting from this idea, for Rosia de Jiu open pit is proposed installing the panels on the steps exposed to the south, where the incidence of sunlight is highest, and on the interior waste dump so that solar radiation is perpendicular on the solar collector. On slopes with northern exposure are recommended to fit the connecting stations and transforming stations with inverters, and the unoccupied surfaces should be grassed or even planted with trees or shrubs, if they do not jeopardize the smooth operation of photovoltaic panels (fig. 3)

Fig. 3. Surfaces available for the construction of the photovoltaic park depending on their orientation Given the approximately 1,000 hectares at disposal, and taking into account both the variability worldwide of the percentage of actual occupation of the land by panels and other structures necessary for the development and optimal operation of the park, namely 35 - 90%, and morphological conditions of the land occupied by Rosia de Jiu open pit, it is proposed the minimum effective occupation of the land (with the possibility of increasing the occupancy) as follows:  ≈300 ha - photovoltaic panels;  ≈50 ha - connecting station, substation and inverters, driveways for maintenance works and fences;  ≈650 ha - green spaces. Recently in Romania, in Timis county, was built a photovoltaic park on an area of 44.14 ha (located within the locality Bencecu de Sus) which consists of 84,480 photovoltaic panels, with an installed capacity of 20 MW, the contribution to the National Energy System is estimated at 25,628 32

MWh/year (25.6 GWh/year). Compared to these values, results that the area available in Rosia de Jiu mining perimeter (1000 ha, of which 255 ha actually filled with panels), involves the installation of approximately 1.7 million photovoltaic panels with an installed capacity of 374 MW, which under a clear sky at a rate of 40-50% per year and an average of 9 hours of light per day, would allow to supply the National Energy System with approximately 500-600 GWh/year. The advantages are considerable and include: regenerative capacity of the resource, production of electricity without negative environmental impacts, long life, easy operation, high resistance. The disadvantages are represented by the impossibility to provide constant energy due to the alternation of day and night or on cloudy days, the high cost of installation (with the advantage of generating free of costs electricity through the system’s lifecycle) and occupation of large areas of land.

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Even if initial investments are impressive, such a project can provide large amounts of electricity, and the costs can be balanced over time. This system significantly reduces harmful gas emissions resulting from electricity generation in traditional power plants and, not least, being clean energy, participates and supports the sustainable development of the society. 3.3 Construction of a municipal waste recycling center Increasing recycling of reusable materials reduces the consumption of natural resources and, therefore, the level of pollution of the environment. Municipal wastes consist of: paper, cardboard, plastic, glass, aluminum, wood, electrical and electronic equipments, waste from parks and gardens, biodegradable fractions and waste from construction and demolition. Recycling from waste involves an intermediate processing of materials (sorting, shredding and/or compaction), transport, recovery of materials and final processing. The center for municipal waste recycling will occupy the existing premises and will manage waste from nearby localities. Premises available from Rosia de Jiu open pit occupy about 6 ha and can be used in carrying out sorting, crushing and baling. Transporting them to entrepreneurs specializing in recovery and final processing of waste can be done by rail or road. Development of the collecting infrastructure must be made so that the value of recovered materials to cover the costs of collecting, processing and transport. To increase the degree of recycling is recommended to implement efficient systems or centers of selective collection of municipal waste in each locality, as well as educating, encouraging and empowering people regarding the need for recycling. Waste collection can be done by taking waste directly from the manufacturer (collected on categories) by a company that processes them, either by transporting waste to collection centers by the producers themselves. The main advantages consist in conservation of natural resources and reduction of waste storage facilities. A complex center for collection and recycling of household waste can contribute to the sustainable development of society through the application of appropriate management and waste processing practices, having positive effects on the environment, community and local and even national economy.

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3.4 Alternative solutions for land reuse Implementing the solutions listed above is a correct and rational choice, allowing the reuse of the land affected, bringing benefits to local communities through the production of renewable energy, replacing the amount of energy produced from lignite, when mining operations in Rosia de Jiu open pit will stop, but also by encouraging recycling and reusing of waste, actively participating in resources conservation and reduction of municipal waste deposited. A major problem is that the mining basin is part of an agricultural area with high productivity while being an area with high potential of solar energy. Conditions in the location and morphology of the land, the adjacent ecosystems and communities, allows reusing the land for other purposes. Here are some alternatives:  Productive reuse. The land affected by mining is part of highly productive farmland. Before starting lignite exploitation activities, the mining area was occupied lands destined for forestry and agriculture (arable and grassland), so when the approved of exploitation rates are achieved, the land may be remodeled and reconstructed, so it may go back into the productive economic cycle.  Recovery for recreation and leisure. The land, being near inhabited areas, can be reused for recreation and leisure. The residual hole of the open pit will be filled with water to create a mirror of water (lake) and in parallel with the construction of specific structures for the upcoming destinations (which can be a place of picnic, camping, sports etc.) will recreate the natural landscape with green areas, forests, positive landforms and various elements necessary in shaping the landscape. In this case, the construction of underground waterproof screens is no longer required.  Recovery for controlled landfill. Uncontrolled growth in the quantity of household and/or industrial waste requires the allocation of new spaces for storage. Storing waste on land areas already degraded is a rational choice, especially where there is a residual hole, whose physical, chemical and biological characteristics allow its use for this purpose in conditions of maximum security for the environment and community. [4] So choosing the best solution requires numerous ecological, economic and technical analyzes and studies, consultation of local communities being essential, so that the type of reuse chosen to have the capacity to meet their needs, bringing long-term benefits.

4. Conclusions Sustainable development aims at the constant improvement of quality of life and well being of present and future generations by empowering society, creation of sustainable communities able to manage rationally natural resources and promoting the reduction of the ecological footprint. This can be accomplished by encouraging reduction of resource consumption, increasing recycling and reuse of waste and minimize the extent of damage and pollution of the environment by applying the best practices of mining and management of natural resource. A mining exploitation must be efficient in terms of resource management, so it needs a mining management team composed of experts from different fields to work together in adapting, changing and modernizing technologies and current practices, leading the development of a ecoefficient mining, satisfactory in terms of profitability and gentle in terms of environment and community. For choosing solutions to reuse lands affected by mining there are necessary ecological, economical and technical analyzes and surveys, to establish exactly what is the best solution. For the reuse of land it is essential to consult local communities, so that the type of reuse will have the ability to meet their needs, bringing long-term benefits. The solutions presented are fair and reasonable options that can be applied globally, allowing exploitation of mineral resources by applying sustainable industrial practices and recovery and reuse of land, after reaching operating quotas, for activities capable of reaching the primary objective: sustainable development.

5. Nyari, I.M., Lazăr, M. Extraction of lignite from Oltenia in the context of sustainable development, Al XIV-lea Simpozion Național Studențesc “Geoecologia”, Ministerul Educației și Cercetării Naționale, Universitatea din Petroșani, Facultatea de Mine, ISSN 1842-4430, Petroșani, (2016). 6. *** - http://forum.bulk-online.com/showthread.php? 23616-Innovative-Dust-Suppression-Device 7. *** - http://www.anpm.ro/anpm_resources/migrated _content/uploads/107353_Evaluare%20impact%20F oto%201_Pischia.pdf 8. *** - http://www.geoengineer.org/education/webbased-class-projects/geoenvironmental-remediationtechnologies/impermeable-barriers?start=1 9. *** - http://www.rockproducts.com/technology/ automation-a-energy/13120-stellar-energy-looks-tothe-solar-system-for-quarryoperations.html#.V8adblt97IU

References 1. Lukhele M. J., Surface auger mining at Rietspruit Mine Services (Pty) Ltd, The Journal of the South African Institute of Mining and Metallurgy, SA ISSN 0038-223X/3.00+0.00, (2002). 2. Laurence, D. et al. A guide to leading practice sustainable development in mining, ISBN: 978-1-921812-48-4 (paperback)/978-1921812-49-1 (online PDF), Australian Government, Department of Resources, Energy and Tourism, (2011). 3. Lazăr, M. Recovery and capitalization of thin lignite layers from Oltenia open cast mining perimeters, Ph.D Thesis, Universitatea din Petrosani, (1998). 4. Lazăr, M. Rehabilitation of degraded land, Ed. Universitas, Petroșani, (2010).

Revista Minelor / Mining Revue - nr. 1 / 2017

Aims & Scope Revista Minelor - Mining Revue publishes original and advanced research papers, new developments and case studies in mining engineering and technologies aiming new and improved techniques also suitable for civil applications. The journal covers all aspects of mining, environmental issues and technologies relating to exploration, exploitation and processing of mineral resources, mining survey, computers and simulation, performance improvement, cost control and improvement, all aspects of safety improvement, rock mechanics and interface between mining and law. Environmental issues specially identified for coverage include: Environmental impact assessment and permitting; mining and processing technologies; waste management and waste minimization practices; mine site closure, decommissioning and reclamation; acid mine drainage. Mining issues to be covered include: Design of surface and underground mines (economics, geotechnical, production scheduling, ventilation); mine optimization and planning; drilling and blasting technologies; material handling systems; mine equipment. Computers and microprocessors and artificial intelligence based technology used in mining are also covered. The papers have a wide ranging and interdisciplinary topic choice. The editors will consider papers on other topics related to mining and environmental issues. All published research articles in this journal have undergone rigorous peer review, based on initial editor screening and anonymous refereeing by independent expert referees. Subject coverage Mining exploration,Mine planning and design,Drilling and blasting,Mining survey, Materials handling - excavation, haulage and disposal,Mining rock mechanics and ground control, Mine drainage,Mining process control and optimization, Computers, micro-processors and artificial intelligence based technology used in mining,Mine information technologies, Mining mechanization, automation and robotics, Reliability, maintenance and overall performance of mining systems, Emerging technologies in mining and mineral engineering, Interaction between minerals, systems, people and other elements of mining and mineral engineering, Simulation of mining systems, Mining health and safety, Environmental impact assessment, Mineral economics, Business systems in mining engineering, Risk assessment and management in mining and mineral engineering, Mining sustainable development

Editorial team: Luminiţa DANCIU - University of Petroşani Radu ION - University of Petroşani Nicolae Ioan VLASIN - I.N.C.D. INSEMEX Petroşani The author has the responsibility for the contents of the paper. Unpublished papers will not be returned. © Copyright by UNIVERSITAS Publishing House Petroşani / Revista Minelor - Mining Revue published quarterly. Editorial offices Editorial correspondence should be addressed to the Editor in Chief : Ilie ONICA, e-mail: onicai2004@yahoo.com or to the managing editor: Radu ION, e-mail: radu_ion_up@yahoo.com University of Petroşani, 20 Universităţii str., 332006 Petroşani, Romania Phone +40254 / 542.580 int. 259, fax. +40254 / 543.491 Permission is granted to quote from this journal with the customary acknowledgment of the source. Bank account: RO89TREZ36820F330800XXXX C.U.I. 4374849 Trezoreria Petroşani http://www.upet.ro/reviste.php ISSN-L 1220 – 2053 ISSN 2247-8590 Revista Minelor /Mining Revue was registered by the National Council for Scientific Research in High Education (CNCSIS) in the cathegory B+ Revista Minelor is indexed by the International Database http://www.ebscohost.com/titleList/a9h-journals.pdf Printed by University of Petroşani Printing Department

Instructions for authors • Papers must be written using the program MS Word (or equivalent). • Authors need to have the following page settings: A4 page format, Up/Down/Left/Right - 2cm, Header/Footer - 1,25 cm. • The font used is Times New Roman. • The paper must contain an abstract max 150 words and 4 keywords. • Title is centered, capital letters, 14p. After title one free line 12p, then the name of the authors centered, italics, 12p, surname with capital letters. Author affiliation is written as footnote. • Main body text is written with 11p letters, on two equal columns size 8,1 cm. Chapter titles are written without alignment, bold, while chapter subtitles without alignment, bold, italic. One free line after every chapter title. Paragraph alignment is 0.7 cm. • Tables may be inserted on columns or on the whole page width, depending on size. Table title is written above it, 11p, italic, while table text is written using 11p letters. • Figures may be inserted on columns or on the whole page width, depending on size. Figure description is written below it, 11p, italic. • References are written with 10p characters. • Do not insert page numbers.