Geological related acid mine drainage of gold tailings and coal waste materials : a comparative study

Abstract

The study is aligned with the mining industry’s transformation requirements using a range of combination of methods from quantitative to qualitative and action-based methods. Most sources of metal trace elements in the environment are from anthropogenic activities, in these cases, from mining sites. However, soil and/or mine pollution has had a number of lower profiles and is not so well visible and understood. Most importantly, previous research focused on Net Acid Potential; hence, in this comparative study case, the project will focus on the geochemical presence of Acid Mine Drainage (AMD) in gold mine tailings, coal waste materials, as well as associated metal trace elements that are leaching out of these tailings. The study utilises a wide range of methods from humidity cell testing (HCT), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), to Portable X-ray Fluorescence (P-XRF) and microwave digestion to identify and quantify the total soluble metal trace elements in the tailings. Geochemical variation in gold tailings and coal waste material, top soil and sub-soil were measured in the laboratory by using ICP-MS to identify metal trace elements including: aluminium (Al), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), lead (Pb) and uranium (U), whereas XRF was used for analysis of gold tailings, coal waste materials and soils. Experiments were performed to determine the geochemical parameters in the AMD, which were pH, Electrical Conductivity (EC) and Oxidation Reduction Potential (ORP). It was discovered that when the pH decreases the ORP increases; this represents the oxidation state and formation of AMD. The results from the study uncovered the acidity potential that will lead to formation of AMD. The study concludes that gold tailings and coal waste materials do influence the geochemistry and geological presence of AMD and are contaminating the research sites. This study concentrated on the influence of metal trace elements concentrations in gold tailings, coal waste materials, topsoil and sub-soil. Keywords: gold tailings, coal waste materials, metal trace elements, leaching, mine pollution, soil contamination. Die studie is in lyn met die mynbedryf se transformasievereistes deur van 'n verskeidenheid kombinasies van metodes gebruik te maak van kwantitatiewe tot kwalitatiewe en aktief gebaseerde metodes. Die meeste bronne van metaalspoorelemente in die omgewing kom van antropogeniese aktiwiteite, in hierdie geval in myngebiede. Grond en/of mynbesoedeling het egter 'n aantal laer profiele gehad en is nie so goed sigbaar en verstaanbaar nie. Die belangrikste is dat vorige navorsing gerig was op Netto Suurpotensiaal, dus in hierdie vergelykende studiegeval sal die projek fokus op die geochemiese teenwoordigheid van suur mynwater dreinering (SMWD) in goudmynuitskot, steenkoolafvalmateriale, asook geassosieerde metaal-spoorelemente wat uitvloei. Hierdie studie maak gebruik van 'n wye verskeidenheid metodes, naamlik humiditeit-seltoetse (HCT), induktief gekoppelde plasma massaspektrometrie (ICP-MS), draagbare X-straal Fluoressensie (P-XRF) en mikrogolf-vertering om die totale oplosbare metaal-spoorelemente in die uitskot te kwantifiseer. Geochemiese variasie in goudmynuitskot en steenkoolafval van die bogrond en ondergrond is in die laboratorium gemeet deur ICP-MS te gebruik om metaal-spoorelemente te identifiseer, insluitend: aluminium (Al), chroom (Cr), mangaan (Mn), tster Fe), kobalt (Co), nikkel (Ni), koper (Cu), sink (Zn), arseen (As), kadmium (Cd), lood (Pb) en uraan (U), terwyl XRF gebruik is vir die analise van mynuitskot en grond. Eksperimente is uitgevoer om die geochemiese parameters in die SMA te bepaal, wat pH-meting, elektriese geleidingsvermoë (EC) en oksidasie-reduksiepotensiaal (ORP) ingesluit het. Daar is gevind dat wanneer die pH afneem, die ORP toeneem; beinvloed dit die oksidasietoestand en vorming van SMWD. Die resultate van die studie het die suurpotensiaal waargeneem wat tot die vorming van SMWD sal lei. Die studie het tot die gevolgtrekking gekom dat goudslikdamme en steenkoolafvalmateriale die geochemie en geologiese teenwoordigheid van SMWD wat ondersoek word, die navorsingsareas besoedel. Hierdie studie het gekonsentreer op die invloed van metaal spoorelemente konsentrasies in goudslikdamme, steenkoolafvalmateriale, asook in the onderliggende bogrond en ondergrond.