Mine water geochemistry and management : two case studies and a new treatment method

Love, David (2000-12)

Thesis (MSc)--Stellenbosch University, 2003.

Thesis

ENGLISH ABSTRACT: Mine water, that is all forms of water associated with and affected by mining operations is probably the largest area of concern in the environmental geology of mining. This study looks at the inter-relationship between mine water geochemistry and mine water management. The objectives of this study are: 1. To examine major geochemical processes influencing mine water; 2. To apply new national water and environmental legislation to the mining industry and discover how mine water management will be regulated; 3. To examine the approach of Integrated Catchment Management, and discover how this approach can be applied to the mining industry; 4. To conduct two case studies, where environmental geochemistry, general geochemistry and multivariate analyses are used as tools to investigate groundwater contamination problems in mining areas, and therefore suggest mine water management interventions; and 5. To, considering mine water problems discovered in the case studies, develop a newly-patented chemical treatment method for possible application in the mining industry. The changing legal framework - principally the implementation of the National Water Act (Act No 36 of 1998) and the National Environmental Management Act (Act No 107 of 1998) - is leading to the responsibilities of a mine becoming substantially clearer, and responsibilities which in the past could have been ignored until public outcry will now be difficult to escape. Two case studies are investigated. In both cases, general geochemistry and hydrogeochemistry, coupled with factor analysis are used to determine the major signatures in groundwater chemistry and the major sources of contamination. On the basis of this, management interventions are suggested. In the first case study, Sishen Iron Ore Mine of the Northern Cape, three signatures are identified in the groundwater: a clean dolomitic water signature, and a contamination signature from the mine and one from agriculture. The extent of nitrate and diesel contamination is shown to be related to agriculture, the use of explosives and to mine workshops and depots. Surface water controls may help reduce these problems. In the second case study, West Driefontein Gold Mine of the Far West Rand, two signatures are identified in the groundwater: a clean dolomitic water signature and a signature relating to contamination from the mine. Cluster analysis is used to suggest three groundwater zones, the chemistry of one being fairly clean dolomitic aquifer, the chemistry of the second affected by the mine and the chemistry of the third affected by granites. Contamination is shown to be related to mining operations, especially the slimes dams, and agriculture. Rehabilitation of dams and dumps, as well as surface water controls may help reduce these problems. Considering mine water problems discovered in the case studies, a newly-patented chemical treatment method is examined and tested for possible application in the mining industry. It is shown to be extremely effective for the removal of calcium from water, but less effective for the removal of iron and manganese. More broadly, this study shows the inter-dependence between mine water geochemistry and mine water management, and the need to be multi-disciplinary in approach.

AFRIKAANSE OPSOMMING: Mynwater, dit is aile soorte water wat geaffekteer en geassosieer word met mynbou bedrywighede, is moontlik die grootste rede tot kommer in omgewingsgeologie van mynbou. Hierdie studie stel ondersoek in na die verhouding tussen mynwater geochemie en mynwater bestuur. Die doelwitte van die studie is soos volg: 1. Om die hoof geochemiese prosesse te ondersoek wat mynwater beinvloed: 2. Om die nuwe nasionale water- en omgewingswette toe te pas op die mynboubedryf en te ondersoek hoe die bestuur van mynwater gereguleer sal word; 3. Om die benadering van Gerntegreerde Opvangs Bestuur ("Integrated Catchment Managemement") te ondersoek, en te ondersoek hoe hierdie benadering op die mynbou industrie toegepas kan word' 4. Om twee gevallestudies te doen, waar omgewingsgeochemie, algemene geochemie en multivariant analise gebruik word as middels om grondwater besoedeling in mynbougebiede te ondersoek, en daarvolgens om mynwater bestuurswysigings voor te stel; en 5. Om, nemende in ag die mynwater probleme wat ontdek is in die gevallestudies, 'n nuutgepatenteerde chemiese behandelingsmetode, vir moontlike toepassing in die mynbou industrie, te ontwikkel. Die veranderende regtelike raamwerk - hoofsaaklik die implementering van die Nasionale Waterwet (Wet No. 36 van 1998) en die Nasionale Omgewingsbestuur Wet (Wet No.1 07 van 1998) - lei daartoe dat 'n myn verantwoordelik moet wees om opmerklik skoner te word, verantwoordelikhede wat in die verlede maklik gergnoreer kon word maar wat nou te moeilik is om te ignoreer as gevolg van publieke uitroepe. Twee gevalle is ondersoek. In be ide studies word algemene geochemie en hidrogechemie, saam met faktoranalise, gebruik om die hoof kenmerke te bepaal in grondwaterchemie en die hoof bronne van besoedeling. Deur dit as basis te gebruik word bestuurswysigings voorgestel. In die eerste gevallestudie, Sishen Ystererts Myn in die Noordkaap, is drie kenmerkende samestellings qeidentitiseer in die grondwater: 'n skoon dolomitiese samestelling, en een elk van 'n myn en landbou gekontamineerde samestelling. Die omvang van nitraat en diesel kontaminasie word aangedui as geassosieerd met landbou, die gebruik van plofstowwe, mynwerkswinkels en depots. Oppervlak waterbeheer mag help om hierdie probleme te beheer. In die tweede gevallestudie, Wes Driefontein Goudmyn in die Ver Wesrand, is twee kenmerkende samestellings in die grondwater gerdentifiseer: 'n skoon dolomitiese samestelling en 'n samestelling geassosieer met kontaminasie van die myn. "Cluster" analise is gebruik om drie grondwatersones te identifiseer, die eerste een se chemie stem redelik ooreen met 'n skoon akwifer, die tweede een se chemie is bernvloed deur die myn en die derde se chernie is deur granite bemvloed. Kontaminasie word aangedui as geassosieer met mynboubedrywighede, veral die slikdamme, en landbou. Rehabilitasie van damme en afvalhope, asook oppervlak waterbeheer mag help om die probleem te verminder. Deur die mynwater probleme wat in die gevallestudies ontdek is in ag te neem, word 'n nuutgepatenteerde chemiese behandeling ondersoek en getoets vir moontlike toepassing in die mynboubedryf. Dit word aangewys as uiters effektief vir die verwydering van kalsium, maar minder effektief in die verwydering van yster en mangaan. In die algemeen, wys hierdie studie inter-afhanklikheid tussen mynwater geochemie en mynwater bestuur, en 'n behoefte aan 'n rnultidissiplinere benadering.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/51829
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