A systematic approach for the characterisation of potential elemental risks associated with sulphide-bearing mine waste: A gold waste rock case study

• Systematic approach to identify environmental risks associated with element mobility. • Mineralogy-geochemistry used to assess total, available and time-related element availability. • Streamlined approach to identify elements for assay during ARD testing. • Approach applied to a gold waste rock case study. Acid rock drainage is a common environmental problem associated with mining sulphidic ores and coal. The upfront assessment of the environmental burden associated with the waste is required to develop reliable long-term management strategies. Of importance is the generation and transport of acidic drainage from waste rock deposits. Current approaches to characterise and predict acid rock drainage focus primarily on the potential for acidity generation as a proxy for the overall environmental impact. This paper presents a systematic integrated approach to identify elements in sulphide-bearing mine wastes that pose a potential environmental risk. The approach differentiates between total and available elemental content to identify the elements that pose an environmental risk and immediately eliminate elements that do not. Detailed mineralogical and geochemical knowledge is assessed using methods ranging from semi-quantitative to quantitative and assists in understanding the elemental distribution and host mineralogy. The potential for mobilisation under simulated microbially mediated ARD generating conditions is assessed using Biokinetic tests. At each approach stage, a ranking and scoring method was used to assess the environmental risks associated with the element content. The application of the systematic approach is presented in a case study of a gold waste rock sample, which reduced the number of elements requiring ongoing measurement and monitoring within conventional ARD test work from 29 elements (stage 1) to 5 elements (stage 3). For this waste sample, the mobility of Fe (high environmental risk) and Al, As, Mn and Ni (low environmental risk) should be a particular focus in further prescribed ARD kinetic test work.