Mobility of Metals from Mine Tailings using Different Types of Organic Acids: Batch Leaching Experiment

The presence of toxic metals in mine tailings is a major concern because they are hazardous to ecological system and human health. Hence the mobility of heavy metals is an important factor to look at when assessing risk of pollution or contamination in tailing dump. This study was carried out in order to determine the effect of organic acids on the mobility of metals from mine tailings. Characterization of mine tailings was carried out using XRD and XRF. Batch leaching experiment under different initial pH, contact time, temperature, and concentration was carried out in this study. The results show that Fe and Al were the major elements, whereas quartz minerals were considered as the major constituents in the tailing. The batch leaching studies indicated high mobility of elements at low pH, short exposure time, high concentration of organic acids and high temperature. Increase of temperature resulted to faster release of metals, with maximum concentrations of Fe and Al recorded at 48 hours. Oxalic acid and citric acid were found as best leaching agents. The kinetic studies allowed to predict that the dissolution of metals from tailing samples was mostly diffusion controlled.