China Nonferrous Metallurgy

The hydrochloric acid leaching process of magnesium reduction residue by silicothermic method was studied in this paper. A two-stage hydrochloric acid leaching process was established to avoid the adverse effects caused by the formation of silica gel in the leaching process. The optimum technological conditions of two-stage leaching are determined, which meet the requirements of the designed leaching rate. The experimental results show that the decomposition rate of dicalcium silicate can reach 98.7% under the conditions of initial acid concentration 3mol/L HCl, liquid-solid ratio 5L/kg and leaching time 60min. Under the conditions of initial acid concentration 2.4mol/L HCl, liquid-solid ratio 5L/kg and leaching time 30min, the leaching rates of calcium, magnesium, iron and aluminum can reach 99.15%, 96.45%, 58.43%, 90.21%, respectively. The efficient utilization of magnesium reduction slag is realized.