Process for Separating Zinc and Copper.
U S Pat 3 573 182 1971 Mar; :
A method is described for selectively separating zn and cu by solvent extraction and recovering the metals once separated. e.g., a leach solution containing 50 g of cu and 14.8 G zn/l was prepared by leaching a roasted cu concentrate. The ph of this solution was adjusted to approximately 3 to precipitate the bulk of the dissolved fe. An organic extractant was prepared from a kerosine solution containing 20 vol pct bis(2-ethylhexyl)phosphate and 10 pct isodecyl alcohol by contacting with milk of lime to produce the calcium salt. The zn was extracted countercurrently in 3 stages. The loaded organic was scrubbed with a small amount of dilute acid and the aqueous scrub solutuion fed to the extractors. The aqueous effluent or raffinate had a ph of 3.7 and contained 99.4 pct of the copper fed to the system and 3.4 pct of the zinc. The loaded organic extractant was stripped in 3 stages with 2.5N h2so4 containing 25 g zn/l. Of the zn, 96 pct was recovered in a solution containing 100 g zn and 1.5 G cu/l. The zn stripping solution was purified with zn powder and electrolyzed to produce zn metal at >90 pct current efficiency. The spent electrolyte can be recycled; it was successfully used for stripping the loaded organic in a second run.
U.S. Pat. 3,573,182; March 30, 1971; Chem Abstr. 74:114,702P