APPLICATION OF GEOCHEMICAL CHARACTERIZATION, GEOSTATISTICS AND GEOLOGICAL MODELLING IN ASSESSMENT AND PREDICTION STUDIES ON SELECTED COAL AND GOLD MINE WASTE IN SOUTH AFRICA

Over the years, million tonnes of coal fly ash and gold slime tailings have been produced, which contributed to over 70% wastes generated in South Africa. These wastes contained high concentrations of heavy metals that upon release to the environment will affect the ecosystem. The needs for a comparative study of the environmental impact of coal fly ash and selected mine tailings in terms of pollution of water resources and land is important. Established assessment and prediction studies will create a map on which remediation process can be based on.

This study predicts and highlights the link between gold tailings’ acid potential generation and coal fly ash alkaline potential generation in terms of their leach-ability, metal release, oxidation effect and environmental pollution, despite having different pH environment. In addition, factors that determine Acid Generation are highlighted and to help proffer solution to some lingering problem in AMD.

Mineralogical data (using XRD), Geochemical data (using ICP MS and XRF) including Sequential extraction results and other parameter are integrated into geostatistical and modelling software to generate a link and relationship between leaching determinant phases. Fly Ash and gold tailings shows considerable leaching capacity of 14-28% indicating potential threat posed. The pH medium also plays a part as decreasing pH increases elemental loads discharge. A model is developed to predict the relationships between factors such as the NP and AP, mobility of alumina-silicate, iron oxide and calcium oxide phases, determined the level of contamination that can be expected.