SELECTIVE LEACHING OF A POLYMETALLIC COMPLEX ORE BY SULFURIC-ACID ANDTHIOUREA MIXED WITH SEA-WATER

Leaching of a polymetallic complex ore from Oued El Kebir (Algeria) wa s studied. This ore contains copper, lead, silver and zinc. In additio n to the conventional roasting sulphuric acid leaching, the effect of thiourea as leaching reagent was examined. In both cases all parameter s were investigated and the increase in both lead and silver extractio n by means of adding sea water was shown. Then, to improve the selecti vity, leaching of this ore was carried out first at a 0.1 M concentrat ion of sulphuric acid where both copper and zinc are dissolved. After filtering, the dissolution of the acidified residue was followed using a neutral solution of thiourea which contains 40% (vol/vol) of sea wa ter. This second step allowed recovery of both silver and lead. The gr ain size effect was also studied to optimise lead and silver dissoluti on.