<Original Papers>Sulfuric Acid Leaching of Copper-Containing Dross

Dross and dust from the decop perizing process in the lead smelter contain a considerable amount of copper. An effective method to extract copper from these dross and dust by means of sulfuric acid leaching is established. The results of this experiment are summarized as follows : (1) Copper particles in the dross have nearly spherical form and are coated with lead. While, part of the dross particles are consisted of several copper particles bound each other with lead. (2) It was observed that, when the dross is screened, copper is more enriched in the -32 mesh size fraction than in the +32 mesh. The -100 mesh size fraction of the former has copper concentration as high as 55%Cu and 72 percent of the total copper content in the dross is contained in this fraction. These are considered to suggest that the screening is one of the effective methods to recover copper from the dross. (3) In either copper extraction from the dross with sulfuric acid, or that with ammonia, lead is considered to be oxidized to form lead sulfate. Accordingly, it is suggested that the treatment of the dross with sulfuric acid is more economical than others. (4) In presence of a sufficient amount of oxygen to oxidize copper, the leaching experiment performed at 80℃ and at sulfuric acid concentration of 3.6 N (180 g/l H_2SO_4) is provided with a successful method for extraction of copper. (5) Similar conditions for the extraction of copper from the dross may also provide with an effective leaching of the dust