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| Morsi M. B., Rabah M. A. |
| RECOVERY OF COPPER FROM BRONZE SCRAP |
Abstract
This paper is concerned with the recovery of copper from bronze scrap containing 9-10 % by weight lead and 8-9wt % tin by melting of scrap with or without additives and periodic removal of slag. The slag including PbS, Cu, SnO2 was leached with acid or alkali to recover black copper for improving the overall yield of copper. Experimental study was carried out to investigate the effect of parameters such as time, stoichiometric ratio of sulfide reagent, blowing with oxygen gas and temperature. Refining of copper was explained in the light of a mathematical model assuming that separation of metal inclusions by oxidation complied with the Kuprowski’s formalism given by Wladyslaw.
Results obtained revealed that copper sulfide reagent reacted with lead to form thermally stable lead sulfide (galena). Subsequent lancing with oxygen gas caused dual effects; it activated formation of lead sulfide and simultaneously oxidized tin to stannic acid. The rate of formation of these compounds increases with increasing the reaction temperature up to 1250°C. The extent of removal of lead and tin from the molten bronze scrap was found to be 92.5 % using 1.5 stoichiometric ratio of the reagent. The use of alkali flux promoted a rapid sulfidization and oxidation reactions by decreasing the molten viscosity of the metals concerned. Hot ammonium acetate leached lead from the slag leaving tin oxide as tailings. Acidification of the acetate solution produced the respective lead salt. The overall extent of recovery of copper and the leached salts attained 86% and 97.5%, respectively.
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| Keywords: copper recovery|bronze scrap|slag|acid leaching| |
| No 4 (2004), p. 327-338 |
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