Galvanic Leaching of Copper in Waste Printed Circuit Boards Using Manganese Dioxide in Spent Zinc-Carbon Batteries

Abstract

Spent zinc-carbon batteries and alkaline batteries contain manganese dioxide, but they are bur- ied in landfill sites without being recycled in Japan. Manganese dioxide is nobler than metal copper. The contact between both materials causes galvanic interactions, and manganese dioxide acts cath- ode to be reduced while copper reacts as anode to be oxidized. We have investigated the galvanic leaching of copper in shredded printed circuit 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 1.0. The extraction yield of copper was 90% in the presence of manganese dioxide in 8 hour leaching while 16% of copper dissolved in the absence. Effects of fac-tors such as pH, amount of manganese dioxide and temperature on the leaching of copper were also examined.