Novel oxygen-pressure technology for ferrous ion removal from zinc sulfate solutions

Aiming at a zinc sulfate solution containing a Fe²⁺ concentration of 20.3 g/L produced by a zinc hydrometallurgical plant, a new process was developed to oxidize Fe²⁺ to Fe³⁺ using pure oxygen in an autoclave. Secondary zinc oxide powder was utilized as a neutralizing agent to neutralize the acid generated during the iron precipitation stage. The reaction pH value was rigorously controlled within the range of 3.0 to 4.0. Under the conditions of oxygen partial pressure of 0.35 MPa, reaction temperature of 80 ℃, agitation speed of 450 r/min, and neutralizing agent dosage of 55 g/L, the oxidation and removal of Fe²⁺ from the zinc sulfate solution were achieved within 50 min. The total iron (TFe) concentration in the solution after iron precipitation was less than 2 g/L, and the iron removal efficiency reached 92%.