Experiment Research on the Enrichment of Precious Metals from Nickel-copper-iron Matte

According to the chemical and phase composition of the nickel-copper-iron matte containing precious metals and the progress in enrichment of precious metals from the nickel-copper-iron matte containing precious metals at home and abroad, this paper put forward the process route of enrichment of precious metals and selectively leaching of base metals from the nickel-copper-iron matte by sulfuric acid and sodium hypochlorite. The effects of particle size, leaching temperature, leaching time, amount of sulfuric acid and sodium hypochlorite on the leaching rate of nickel, cobalt, copper and iron are mainly discussed. The results show that raw material particle size has significantly effects on the leaching rate of base metals, high leaching rate of base metals and enrichment of precious metals are obtained with the suitable particle size. Through the experiments, the reasonable experiment parameters and conditions were determined as fellows: particle size of-200 to +250 mesh, leaching temperature 95℃ , leaching time 5 h, sulfuric acid concentration 30%, adding amount of sodium hypochlorite 3 times of matte weight. Under these experiment parameters and conditions, the leaching rate of nickel, cobalt, copper and iron were 97.39%, 96.24%, 98.30% and 99.01%, respectively. The content of nickel, cobalt, copper, iron in the leaching residues was 8.15%, 0.23%, 1.40% and 0.24%, respectively. The content of Pt, Pd, Au, Ag and Rh in the leaching residues was 247 g/t, 521 g/t, 112 g/t, 494 g/t and 24 g/t, respectively. The content of Pt, Pd, Au, Ag and Rh in the leaching solution was 0.0005 g/L, 0.0023 g/L, 0.0007 g/L, 0.0005 g/L and 0.00017 g/L, respectively. This process has advantages as follows: a small investment, simple technology, high enrichment efficiency.