Extraction of valuable metals from manganese–silver ore

A combined novel process was developed to extract valuable metals from manganese–silver ore. The preferential dissolution of manganese from the primary materials was achieved through reductive leaching in dilute sulfuric acid medium with sodium sulfite as the reductant. Silver, which was enriched in the reductive leaching residue, was leached by complexation dissolution with hydrochloric acid and calcium chloride solution. Effects of process parameters on manganese extraction in the reductive leaching process were investigated, including the average particle size, the amount of sodium sulfite addition, sulfuric acid addition, liquid/solid ratio, leaching temperature and time. As for the silver extraction, the effects of Cl− concentration, hydrochloric acid addition, leaching temperature and time were also addressed. The results suggested that the extraction of manganese and silver could reach 99% and 92% respectively at the optimum conditions, while the high silica-containing product was obtained as the final residue.