Copper and zinc recovery from scrap metal - by lixiviation with sulphuric and nitric acid, cementation with iron and contact with zinc oxide

摘要

Process comprises (a) leaching the material with aq. H2SO4 and HNO3 to obt. Cu ions in soln.; (b) filtering off unwanted matter and adding excess Fe to the filtrate to ppte. finely-divided Cu; (c) sepg. and recovering Cu leaving a soln. contg. FeSO4; (d) adding ZnO ppte. as hydrated Fe2O3, leaving ZnSO4 in soln.; (e) removing the solid matter; and (f) evapg. the soln. of ZnSO4 to give solid ZnSO4 which can be calcined to ZnO and re-used at (d), the SO3 also being reclaimed. The process can be used to treat e.g. crushed electric motors.