Counter-current acid leaching process for the removal of Cu, Pb, Sb and Zn from shooting range soil

Abstract

This research explores the performance of a counter-current leaching process (CCLP) for Cu, Pb, Sb and Zn extraction in a polluted shooting range soil. The initial metal concentrations in the soil were 1790 mg Cu/kg, 48,300 mg Pb/kg, 840 mg Sb/kg and 368 mg Zn/kg. The leaching process consisted of five one-hour acid leaching steps, which used 1 M H 2SO 4+4 M NaCl (20°C, soil suspension = 100 g/L) followed by two water rinsing steps. Ten counter-current remediation cycles were completed and the average metal removal yields were 98.3±0.3% of Cu, 99.5±0.1% of Pb, 75.5±5.1% of Sb and 29.1±27.2% of Zn. The quality of metal leaching did not deteriorate throughout the 10 remediation cycles completed for this study. The CCLP reduced acid and salt use by approximately 68% and reduced water consumption by approximately 60%, exceeding reductions achieved by a standard acid leaching process.