Abstract
Large quantities of car-radiator tubes (brass alloy coated with lead-tin layer) are rejected due to manufacturing failures. Metal values were successfully separated from scrap containing 55% copper, 25.5% zinc, 13.2% lead, and 6.3% tin. The scrap was completely leached with hot HCl solution containing HNO
3
as an oxidant. Upon cooling, about 61% of the lead content was precipitated as lead chloride. Tin was separated as hydrated tin oxide at pH 2.6. Copper was then separated by solvent extraction with an aromatic oxime (Acorga PT-5050Z) in kerosene and stripped with 3 M H
2
SO
4
(M = mol/dm
−3
). Zinc was recovered as carbonate at pH 6.5, and the remaining lead was precipitated as hydroxide at pH 9.0.
Complete leaching was achieved using 2.7 M HCl (equivalent to 1.35 stoichiometry) and 0.96 M HNO
3
at 80°C for 1 h. A synthetic solution containing 300 ppm of each metal was first tested. Copper was almost completely extracted with 10% Acorga PT-5050Z from an acidic solution of pH > 1 for 20 min, leaving almost all of the zinc and lead in the aqueous solution. Copper was then separated from the real leach solution (containing in g/L: 36 Cu, 16.2 Zn, and 1.2 Pb) applying three extraction stages with O : A of 4 : 1.