Resource Management efficiency in the mining industry - Scientific Paper

Resource Resource management managementefficency efficency in in the the mining mining industry industry :: AAwater water collection collection system system for for the the industrial industrial evaporation evaporation ponds ponds in in the the Atacama Atacama in in Chile Chile and and in in the the Moroccan Moroccan Sahara.

Sahara.

El ElKendi KendiAbderrahmane Abderrahmane--190138 190138

Abstract Abstract With Withthe theacceleration accelerationofofclimate climatechange, change,water waterscarcity scarcitywill willbecome becomeaahighly highlytangible tangibleissue issuearound aroundthe theworld. world.This This study studyfocuses focuseson onthe theoptimisation optimisationofofthe theindustrial industrialprocess processofofmineral mineralmining miningthrough throughout outevaporation evaporationponds, ponds,aa practice practicethat thatisiscommon commonininaamultitude multitudeofofwarm warmclimates climatesaround aroundthe theworld. world.The Thesite sitechosen chosentotoperform performthis thisstudy studyisis the theAkhfenir AkhfenirNational Nationalparc parcininthe theMoroccan MoroccanSahara Saharawhere wheresalt saltextraction extractiontakes takesplace placeininaalarge largeopen openarea areaofofsolar solar evaporation evaporationponds ponds. .Through Throughthe themedium mediumof ofan anarchitectural architecturaldevice devicethat thatworks workswith withsolar solardistillation distillationininorder ordertoto collect collectwater, water,and andchannel channelitittotoharvested harvestedplants, plants,we wecan cantest testthe thepossibilites possibilitesofofdesigning designingmore moreefficient efficientsystems systemsfor for the theindustrial industrialinstallations installationsthat thatare arebased basedon onthe theevaporation evaporationprocess. process.The Thedevice deviceisisdesigned designedasasaafloating floatingunit, unit, capable capableofofharvesting harvestingthe thecollected collectedwater waterfrom fromponds pondsinto intoplants plantsautonomously, autonomously,with withasasaareference, reference,the theartistic artistic concept conceptofofaa‘tree ‘treeininthe thedesert’, desert’,and andthe theconcepts conceptsofofscalability scalabilityand andmore moresustainable sustainableindustrial industrialactivities. activities.As Asthe the study studyisisinterested interestedininthe thecaptured capturedwater waterand andit’s it’seffects effectson onplants, plants,the theresults resultsare arehence henceenvisioned envisionedtotobe beofof quantitative quantitativenature, nature,testing testingthe theimpact impactofoflocation locationand andweather weatheron onthe thewater watercollection collectionpotential. potential.

Solar Solardistillation, distillation,Evaporation EvaporationPonds, Ponds,Salt, Salt,Lithium, Lithium,Radiation.

Radiation.

Nomenclature Nomenclature ml Volume ml Volumeof ofWater Water W/m² Radiation W/m² Radiationreceived received ..

©©2019-20 2019-20/ /ElElKendi KendiAbderrahmane Abderrahmane

Introduction

During the three first quarters of 2019, Chile has provided approximately 40% of the world’s Lithium consumption, mostly through the extraction ponds that are found in the Salar de Atacama. These evaporation ponds are developed on extremely wide surfaces (200 Millions of square meters) through out the salar and allow the extraction of pure lithium from millions of liters of the desert’s saline water every year. However, and although this process has been very beneficial for the world’s needs in Lithium, it is an extremely inefficient process for the water needs of the indigenous people.

In fact, the lithium percentage in the brine is only 0,16% with the rest of brine water being left for loss through evaporation.

This practice of water evaporation ponds in order to extract minerals is surely not new, as salt ponds have existed for over 4000 years ( in China - up to 2700 BCE ). However, the lithium and salt extraction sites share the same main problem : the evaporation process eliminates a substantially large quantity of useful water, especially in arid or dry areas.

a closed system, with water leaving the system only by evaporation or through use by plants, wildlife or humans. Therefore, any water extraction will have direct consequences on the ecosystems involved, both currently and in its future.’

The aim of this research is to test the hypothesis of whether a simple solution exists to this complex issue of water loss through out the evaporation procedures : we aim to investiagte how much of this water can be captured through the solar distillation procedure, that is with the medium of a prototype that captures the water and then utilizes it to lead the water to plant basins.

The device aims to generate amounts of clean water from the solar distillation process, which will be tested through the comparisons of received radiation within different weather conditions (overcast / rainy/ clear/ night) .

The interest of studying the Atacama Desert lithium pond practice is mainly because the Atacama brine lake bed is a closed water entity, meaning that it is not linked to the Sea or the Ocean or any other rivers, hence the water in the basin can be overused and deteriorated for the future generations.

Previous research by Catherine Ann Somerville Venart for the School of Architecture in Dalhousie University in Canada, states the following : ‘There is no outflow of water into any other water basin or to the sea, making the Salar de Atacama basin

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Salt pond worker - Todo Turismo Group

Background In the process of a rigourous scientific study, it is crucial to understand the existing references and what previous research about the processes of solar distillation have concluded, especially around the area of the Atacama in Chile.

Multiple sources of inspiration have motivated this study, one of the most powerful among these sources is the photography by the International Space Station showing the Atacama desert, and the water evaporation ponds developing on it on a substantially large surface ( ~ millions of square meters ), hence exciting us about the possibilites of the evaporation ponds to extract large quantities of water.

Another interesting inspiration for this project of research is the artistic photography by Mario Ruiz of National Geographic, showing the desert of Atacama blooming with colors of plants after the rare rainfall that takes place in there.

Concerning the scientific state of the art research on the distillation topic, we notice that there is a great amount of data on distillation in a closed volume of

water, where the water condenses on a glass surface after evaporating in the closed medium. Among these research that have been particularly useful for this project are ‘Experimental optimization of a solar still: application to alcohol distillation’ by Meukam et al. and ‘An attempt to solar still productivity optimization; solar still shape, glass cover inclination and inner surface area of a single basin solar still, optimization’ by Hashim et al. These two bodies of research are greatly interested in how the process of solar distillation can be used to optimize not only the quantity of water generated in the same amount of time, but also the quality of the water or the alcohol distilled and it’s clarity. The topic of open air distillation does not seem to be delved into by previous research as it naturally yields lower results than closed volumes, but following our hypothesis it has the advantgage of being an autonomous unit that can function from the open air bodies of water like salt and lithium ponds, allowing us to generate water continuously without human interaction.

Mario Ruiz Photography - Blooming desert

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Sahara Salt Ponds - Author

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Methodology

The device as an entirety is designed to act as an autonomous unit which captures evaporated water and canalizes it into the planting systems in an autonomous manner, meaning that it does optimally not require human interaction in order to feed water and change it continuously, requiring only the presence of good solar radiation and a shallow body of salt water.

In order to test the possibilities of generating useful water content through solar distillation from the evaporation ponds, a portable prototype was designed , with the factors of mobility, scalability and optimal efficiency.

These factors were generated through out designing a central hexagonal unit which consists of a distillation dome and three water collection tanks, interlocking to generate the base of the dome.

Concerning the design of the device, it’s form is developed through a study of the potential received solar radiation by the dome, while minimizing the solar radiation received by the plants within the shading systems.

The central hexagonal unit can be self sufficient if used alone in order to generate clean water from salt water or extracted brine. The dome is vacuum formed with a truss strcutrue in order to give it more structural stability and to optimize the water evaporation flow.

This hence allows for maximum protection of the plants, all while providing sufficient heat for the dome to generate a relatively important quantity of water.

This central unit is then interlocked with tubing and screws with 3 independent square units which allow not only for more stability, but also act as hosts of the planting systems which are fed clean water from the dome.

The square bases also allow for the installation of shading structures which allow to keep the plants safe from high UV radiation in the Atacama Desert.

Hence, this allows for the testing of the efficiency of the optimized design of this form of solar distillation, and allows us to compare with the more pragmatic solar distillation solutions, which are usually served in the form of closed distillation volumes that require heavy human interaction, and do not generally work with the open pond evaporation systems.

Textile

Plastic dome

Shading

Aluminium pipes

2 3

2 1

3 1- Evaporation 2-Condensation 3- Water collection

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Device functioning explanatory section

Atacama Lithium Ponds - ISS Photography

Method Through out the different phases of the experiment, the same material was used : One plastic solar distillation dome of 40 Centimeters of diameter and 1mm thickness after being vacum formed. One aluminium base linking the tanks to the plastic based dome , plus three plastic and polysterene tanks where the distilled water is collected from the solar distillation dome.

Three separate units which are fed water from the three tanks under the distillation dome. These 3 devices are not consistent with the outcome of the scientific research, and hence the experiment may be performed with or without their presence linked to the dome, that will not affect the amount of water collected or the radiation received.

However, the addition of the plant shading systems will influence the radiation received by the dome and hence the amount of water collected.

The procedure of testing goes as follows : Due to visa complexities, and political civil unrest in the desert, this testing was not feasible in the Atacama desert. A highly similar site in the Moroccan Sahara was chosen when considering the weather characteristics : The Khnifiss National parc salt evaporation ponds.

The period is of a 41 minutes of total experiment, all of which is a period where the device is floating on top of the water pond. This is the same period of testing that took place in the Copenhagen solar radiation testing phase.

This 41 minute period is repeated in three different weather conditions : Overcast - Clear - Rainy - Night.

These 4 conditions show how the device reacts to the different quantities of radiation received and the differences of results that may yield.

It is insured that no obstructions of radiation exist between the sky and the solar distillation dome besides the shading systems and the weather state of the sky ( clouds - rain) .

The collected water amount during the test is measured in each of the three tanks and added to a total collected amount as the dispersion of water between the three tanks is of great complexity and not being the topic of this study.

The Solar radiation received by the dome is measured in a punctual manner, on the central and highest point of the dome Measuring tools : In order to measure the solar radiation, a Hoboware Silicon Pyranometer sensor device ( S-LIB-M003) was used .

The water collection system tanks collected water after 41 minutes was poured in a measurement glass and a reading of the collected water was performed, this did not include water that had not condensed to the tanks yet, but was present on the surface of the dome.

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Results

W/m² 500 450

400 350

300 250

200

~12 ml

Clear

150 ~4 ml

100

Overcast

50 N/A

00 Radiation

0s

41 min

Rainy Time

Results from device testing conditions Radiation analysis in 3 different weather conditions Akhfennir / Moroccan Sahara / 17 - 12 - 2019

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Solar distillation device Photography / Author

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Discussion

After testing the prototype in three distinct weather conditions ( four including night time where radiation = 0 ), we were able to collect a total of ~16ml during 3 increments of 41 minutes.

One of these increments had the highest yield, which was around 12 ml of collected water. That is of course, a negligible amount of water for adequate human usage, but it shows the potential of the device in harvesting clean water. If this was to be used on longer periods of time, it would yield more water, especially if the position of the device is kept relatively static, as intensive movement seems to disrupt the cycle of the device.

Study limitations Through out the course of the experiment and the data collection procedure, a multitude of points of interest arise.

These can be described as failings or inaccuracies of the study, which may have been caused by multiple constraints of different natures.

First of all, the radiation studies performed on the device during the study phase were based on weather data files ( EPW ) of the Atacama Desert, in Chile.

However, the device was only tested in Copenhagen, and in the Khnifiss National Parc in the Moroccan Sahara. And although this one is considered assimilated to the Atacama weather, that similarity is not a symmetric resemblance on a rigourous scientific approach, although the annual radiation and temperatures of both sites can be quite similar during certain periods of the year.

Secondly, one main set of failings that have been noticed during the experiment part are related to the principal issue of open-air distillation. This does not seem to be a very efficient way of collecting water as it has yielded very poor results compared to a theoretical closed distillation device.

The maximum we were able to collect during the 41 minute test periods was 3 ml of water which is very negligible if it is intended to work as a serious source of water for the communities that can benifit from it.

This can be avoided if the device is made to float in the same point on the water by fixing it to the ground instead of letting it float freely.

Moreover, another very important factor that was frowned upon in the design procedure is the wind, this did not allow us to predict the movement or stability of the device, as it did go through structural stability and motion issues which could have influenced the outcome of the study.

It could also have been more efficient if the junction between the plastic dome and the aluminium base would have been more insulated so that the water heat within the dome would be well-kept. It is of conjuncture that this would have allowed better results in water collection.

Concerning the measurement tools, as the hoboware data logger was not waterproof, and in order to avoid damage to the device used for measurement, it was only measured off water for a similar 41 minutes in the similar conditions of the device being on the water. This may lead to different results to the one registered by the dome as the water reflection could lead to more intense radiation from reflection.

While many lackings have took place during the establishement of this research, I am curious about the possibilites of creating a system that would autonomosly isolate a small body of water for distillation in the dome, meaning a secondary tank that would enclose the water for optimal heat exposure in the water.

The multitude of these issues show that a series of design iterations, and also measurement otpimization could be necessary in order to generate a more successful attempt to collect evaporated water.

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Conclusion

As a concluding statement, and although this is a very promising attempt to creating new sources of water extraction from the industrial activities of evaporation ponds, the reality of the device being a completely free floating unit, with no closed volume of water to distill greatly lowered the capabilities of the device to capture evaporated water.

We hence conclude that this system can yield around ~130 ml per full day of intense radiation received (extrapolated from 40 minute increments information).

The efficency of the device is relatively low as 130 ml per day are not sufficient for harvesting plants, but if optimized correctly, this can be developed

to yield much more (with less motion, and thicker plastic for the dome for heat insulation).

This outcome was also lowered by a series other factors such as the varying weather conditions, the wind intensities that differed from one point in time to another, and the design problematics that could have influenced the outcome.

With all that taken into consideration, the fact that small amounts of water were indeed collected using this method invites the possibilities of expanding and correcting the design proposals towards a more optimal and efficient future for water collection from the industrial processes of solar evaporation ponds.

Device night testing

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Bibliography 1/ Catherine Ann Somerville Venart, Water resources a documentation of water technologies in the Atacama , Dalhouie School of Architecture, Canada 2013 «http://aridjournal.com/water_resources_catherine-annsomerville-venart/» 2/ Denevan, William. Cultivated Landscapes of Native Amazonia & the Andes, Oxford UK, Oxford Geographical & Environmental Studies, 2001 3/ RIDES (2005). Bienestar humano y manejo sustentable en San Pedro de Atacama, Chile–Resumen Ejecutivo (Human well-being and sustainable management in San Pedro de Atacama, Chile–Executive Summary), Santiago, Chile: RIDES. Santiago, March 2005 RIDES (2005). p. 36.

4/ Pierre Meukam, Donatien Njomo, Aboudramane Gbane, Siaka Toure, Experimental optimization of a solar still: application to alcohol distillation, Chemical Engineering and Processing: Process Intensification, Volume 43, Issue 12, 2004, Pages 1569-1577, ISSN 0255-2701, https://doi.org/10.1016/j.cep.2004.02.007.

5/ Y. Hashim, Aqeel & Al-Asadip, J & Alramdhan, Wathiq.

(2010). An attempt to solar still productivity optimization; solar still shape, glass cover inclination and inner surface area of a single basin solar still, optimization. 39-48.

6/ Nguyen The Bao , The Mathematical Model of Basin-Type Solar Distillation System. DOI: 10.5772/intechopen.83228 https://www.intechopen.com/books/distillation-modellingsimulation-and-optimization/the-mathematical-model-ofbasin-type-solar-distillation-systems 7/ Factors Affecting the Yield of Solar Distillation Systems and Measures to Improve Productivities.

DOI: 10.5772/intechopen.75593 https://www.intechopen.com/books/desalination-and-watertreatment/factors-affecting-the-yield-of-solar-distillationsystems-and-measures-to-improve-productivities 8/ H.M. Qiblawey and F. Banat: Desalination Vol. 220 (2008), p.633.

9/ R. Dev and G.N. Tiwari: Desalination Vol. 245 (2009), p.246.

10/ Verma, Vinod Kumar, Ivan Sunit Rout and Abhishek Gaikwad. “Optimization of parameters affecting the performance of passive solar distillation system by using Taguchi method.” (2013).

Acknowledgments Associate Professor Emanuele Naboni , Institute of Building Technology, The Royal Danish Academy of Fine Arts, Copenhagen Associate Professor David Garcia, Institute of Building Technology, The Royal Danish Academy of Fine Arts, Copenhagen Associate Professor Thomas Chevalier Bøjstrup, Institute of Building Technology, The Royal Danish Academy of Fine Arts, Copenhagen Associate Professor Runa Johannessen, Institute of Building Technology, The Royal Danish Academy of Fine Arts, Copenhagen Assistant Professor Will Perkins, Institute of Building Technology, The Royal Danish Academy of Fine Arts, Copenhagen Mads Johansen, Metal and Experimental Workshop, The Royal Danish Academy of Fine Arts, Copenhagen