Abstract:In order to obtain crude cobalt hydroxide products in line with industry standards, reduce content of impurity magnesium in products and increase enterprise profits, crude cobalt hydroxide was prepared by two-stage cobalt precipitation process applying pre cobalt precipitation solution as raw materials. When first stage cobalt precipitation is conducted under the conditions including reaction temperature of 45 ℃, stirring speed of 900 r/min, magnesium oxide slurry concentration of 10%, reaction time of 4 h, and pH value of reaction end point of 7.4—7.5, and then cobalt precipitation is washed for 20 min under the conditions of stirring speed of 170 r/min and L/S of 4:1, the laboratory index of crude cobalt hydroxide product containing 35% cobalt and magnesium content of 6% below is obtained, which meets the requirements of secondary level industrial products. Cobalt concentration in final solution can be reduced to 0.05g/L below under the conditions of cobalt content in second-stage cobalt pre solution of 0.27 g/L, temperature of 30 ℃, precipitation with 15% lime slurry, reaction time of about 2 h, and pH value of reaction end point of 7.9~8.2. When terminal pH value is 9.5~12, magnesium concentration in solution is lower than 1 g/L, which meets the environmental protection requirements of direct discharge.