Mobility and Behaviour of Metals in Copper Mine Tailings and Soil at Khetri, India

The mobility and behaviour of metals (Cu, Zn, Ni, Cr, and Pb) in mine tailings and neighbouring soils were studied in the Khetri copper mine region, Rajasthan, India. Single reagent extraction was used to assess the mobility and availability of metals, while sequential chemical fractionation (water soluble, acidic, and reducible) was used to evaluate their behaviour in the environment. Samples were divided into two different physical grain size fractions to assess the impact of grain size on extraction. The mobility trend in both tailings and soil followed the order Ni > Zn > Cu. Metals of lithogenic origin (Cr and Pb) were less extracted in the water soluble fraction or non-residual fractions than those associated with mining. The acid leachable fraction was high in the tailings due to the presence of sulphide minerals. Hence, acidification of tailings would enhance leaching of metals. Results of single and sequential chemical extraction indicate that the Cu, Zn, and Ni are anthropogenic, as they were mostly associated with the non-residual fraction of the soil.