<Original Papers>On Detinning of Lead Alloys

Owing to the great deficiency of lead in Japan in 1944,the recovery of pure lead from lead alloys, for example, various type-metals and the reclaimed scrap from such products, has been carried out for trial by means of the Betts electrolytic process, but the tin, among various impurities, has been found to interfere greatly with electrolytic refining by fouling the electrolyte and being deposited together with lead on the cathode. Accordingly some experiments on the removal of tin from lead alloys, i.e., tin-bearing antimonial leads and solders, as a prelimenary to electrolytic process, were carried out by means of simple oxidation ("softening") and the oxidation in the presence of lead chloride ( U.S.pat. 2,043,573). A) By simple oxidation the following result is obtained.a) The tin contained in relatively small quantity in lead alloys (for example 5% tin alloy) can be completely removed at a temperature between 700 and 900℃., being coverted into oxide which combines with the lead oxide (about twice as much as tin) formed at the same time. B) By the oxidation in the presence of lead chloride the following results are obtained. a) The tin contained in relativley small quantity in lead alloys can be removed at a temperature between 650 and 70O℃., but this treatment does not seem to be better than simple oxidation. For the complete removal of tin certain amounts of lead chloride (1.2-2 times the quantity of tin) and lead oxide (twice as much as tin) are required while some portions of the latter (2/5-9/10 times the quantity of tin) are slagged off with tin oxide, the remaining portion being reduced to lead by tin. b) The removal of tin from solders (approximately 40% tin and 60% lead) is impossible by simple oxidatin, while it is possible by the lead chloride-oxidation treatment. In this instance certain amounts of lead chloride (equal quantity of tin) and lead oxide (twice as much as tin) are required while 43 per cent of the latter is slagged off