Abstract:Dissolution of magnesium from magnesium-bearing silicate minerals of low-grade nickel sulfide ores in acid leaching systems affects extraction of valuable metals. Effect of Mg2+ on oxidation leaching of nickel, copper, magnesium, and iron from low-grade nickel sulfide ore was studied in different oxidation acid leaching systems. Performance of Mg2+ on electrochemical behavior of sulfide minerals ore during oxidation leaching was investigated by method of cyclic voltammetry, potentiodynamic polarization, and alternating-current impedance. The results show that, in the test range, oxidative dissolution of sulfide minerals from low-grade nickel sulfide ore is controlled by diffusion of products. Magnesium minerals are dissolved by sulfuric acid generating Mg2+ in leaching liquor. Dissociative Mg2+ affects electron transfer and product diffusion in sulfide minerals oxidation leaching. Mg2+ absorbs electronegative points on surface of sulfide minerals, leading to an acceleration on charge transfer process due to decrease in charge transfer resistance of interface electric double layer. While, this absorption causes formation of corrosion products film tending to dense which has negative influence on sulfide minerals oxidation leaching. Self-corrosion rate of ore drops with increase of Mg2+ concentration. Presence of Mg2+ has poor effect on transform between sulfur-containing substances. Collaborative influence of Mg2+ and Fe3+ illustrates that low concentration of Mg2+ in leaching system facilitates cycle of Fe3+/Fe2+ pair, and high concentration of Mg2+ reduces oxidizing leaching efficiencies of minerals because of densification of oxidation products layer. Leaching efficiencies of Ni, Cu, and Fe during oxidation leaching with existence of Mg2+ in solutions are lower than those with absence of Mg2+.