Pyrite enhanced chlorination roasting and its efficacy in gold and silver recovery from gold tailing

Abstract

Developing cost-effective, efficient and environmentally friendly recovery process for gold tailings is imperative for environmental protection and resource recycling. In this paper, we developed a pyrite enhanced chlorination roasting technology and it was first used to dispose gold tailing. Here, we show that addition of pyrite could promote calcium chloride oxidation to produce chlorine gas, and the process realized the recovery of gold (Au) and silver (Ag) from gold tailing in an efficient and environmentally friendly way. Notably, addition of pyrite also has the potential to enhance the chlorination roasting in other fields. The experimental results confirmed that 86.93% Au was recovered by pyrite enhanced chlorination roasting under the roasting temperature of 900℃, however, without pyrite the value only of 44.27%. In addition, FeS2 and CaCl2 were converted to CaSO4 and Fe2O3 during the pyrite enhanced chlorination roasting while gaining Cl2 to extract Au and Ag from the gold tailing. The effects of different parameters on the recovery efficiencies of Au and Ag were examined. Through this technology the recovery efficiencies of Au and Ag could reach 98.56% and 87.92%, respectively, under the optimal conditions.