RECOVERY OF NON-FERROUS METALS FROM ALLUVIAL TECHNOGENIC SANDS BY LOW-TEMPERATURE ROASTING WITH AMMONIUM SULFATE

Abstract

Research has been conducted on the roasting of copper-nickel alluvial technogenic sands of the Nalednaya River deposit (Norilsk region). For the experiments, the –100 µm class was separated from the sand, the nickel and copper contents in the class were 0.32 and 0.22 %, respectively. During the work, the material composition of the original sands and experimental samples was studied, as well as the optimal mode of their processing by the method of low-temperature roasting with ammonium sulfate was selected. Sand samples were mixed with ammonium sulfate, and then the roasted mixture was leached in water for 40 min with constant stirring at an intensity of 230 min^-1. The sands are characterized by a significant number of intergrowths containing multiple ore inclusions. Free from sulfide intergrowths, about 1 %; pyrrhotite is largely oxidized. Using the X-ray phase analysis method, among the sulfides, in addition to pyrrhotite, the presence of chalcopyrite was noted. The maximum recovery of metals was achieved at a roasting temperature of 400 °C and a mass ratio of sand and ammonium sulfate of 1:3; the nickel recovery was 73.2 %, copper – 71.6 %.