Galvanic Leaching of Waste PWB Boards Using Manganese Oxide in Spent Zinc-Carbon Batteries

摘要

Spent zinc-carbon batteries and alkaline batteries contain manganese oxide, but they are buried in landfill sites without being recycled in Japan. Manganese dioxide is nobler than metal copper. The contact between both materials causes galvanic interactions. Manganese dioxide could act as cathode to be reduced while copper could react as anode to be oxidized. We have investigated the galvanic leaching of copper in shredded printed wiring boards using manganese dioxide recovered from spent zinc-carbon batteries. The dissolution of copper was enhanced in the presence of manganese dioxide in sulfuric acid solution with pH 0.8. The extraction yield of copper was 92 % in the presence of manganese dioxide in 24 hour leaching while 45 % of copper dissolved in the absence. Effects of factors such as pH, manganese dioxide dosage and temperature on the leaching of copper were examined.