Recovery of Zinc-Manganese Alloy from Spent Dry Battery Cells

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Mahmoud A. Rabah, Sabah Foda

This study shows a comparative result of the recovery of zinc-manganese alloy from used dry batteries by chemical method and electro deposition technique.

The used batteries were disassembled and its content was freed from steel discs, paper and copper cap. Zinc and black past contents were rinsed with warm water, filtered and dried. Black paste was separated by sieving. Part of the black past containing manganese oxides such as Pyrolusite (β & γ MnO2) and carbon were heated under inert atmosphere at temperatures up to 1050 °C whereby the mineral (MnO2) was reduced to manganese metal. Corroded zinc cans was melted at 500 °C and purified by skimming.

Molten manganese was alloyed with zinc to obtain the alloy. Other part of the corroded zinc cans and black paste were leached with sulphuric acid to yield their respective sulphate salts. The ionic solution was filtered, neutralized with ammonia and treated with hydrazine hydrate to reduce the ionic species to yield ultra fine particles of zinc and manganese metals. Alternatively, the two metal ions in the solution were co-electrodeposited using current density 12 mA/cm2 and 20 – 24 mV DC, using two graphite electrodes. The two co-deposited metals were washed and re-melted under inert atmosphere to yield the zinc-manganese alloy.

The products were characterized by XRD and scanned with electron microscope Type Phillips. Results revealed that the recovery efficiency of the chemical and electro deposition methods amounts to 82 and 94 % respectively. Electrolysis method was found more simple and pure as compared to the chemical methods.

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