Zinc recovery from liquid and solid industry wastes by hydrometallurgical methods

Some processes to recover zinc from aqueous and solid metallurgical wastes by hydrometallurgical methods are reported. In the case of waste liquid effluents, two different ways to recover zinc from the waste electrolyte of a zinc electrowinning plant are considered: in a first way sulfuric acid was extracted by iso-butyl alcohol (IBA) before extracting zinc by di-2-ethil-hexyl phosphoric acid (D2EHPA); in the second way zinc was directly extracted by tri-n-butyl phosphate (TBP). In the case of solid industrial wastes the zinc recovery from both electric arc furnace (EAF) dusts as collected, and fumes coming from pyrometallurgical treatment of EAF dusts was investigated by means of aqueous sulfuric acid leaching, purification of leach liquor both by iron precipitation or solvent extraction. In all the studied cases the zinc purified solutions are suitable for zinc electrowinning: high current efficiency and low specific energy consumption are obtained with a high quality zinc deposits.