Selective recovery of valuable metals from nickel converter slag at elevated temperature with sulfuric acid solution

High pressure oxidative acid leaching (HPOXAL) was employed to extract valuable metals from nickel converter slag. Parameters such as sulfuric acid concentration, temperature, liquid/solid (L/S) ratio, leaching time, oxygen partial pressure and particle size were investigated to optimize the solubility of metal values and improve the solid-liquid separation characteristics of the leaching slurry. A highly selective leaching of valuable metals with extraction of >97% for cobalt and nickel, >95% for copper and <0.4% for iron was successfully achieved under the conditions of -150 + 74 mu m particle size, 0.3 mol/L sulfuric acid concentration, 7 mL/g liquid/solid (L/S) ratio and 600 kPa oxygen partial pressure at 200 degrees C for 80 min. Under the conditions, less than 2% silicon was dissolved, and the leaching slurry performed a good solid-liquid separation characteristics with a filtration rate of 433.73 L/m(2) h. The residue containing hematite, silica and <0.1% bases metals was suitable for further disposal. (C) 2015 Elsevier B.V. All rights reserved.