Leaching of zinc and manganese from used up zinc-carbon batteries using aqueous sulfuric acid solutions

Zinc-carbon and alkaline zinc-manganese dioxide batteries are widely used for powering small appliances as they have favorable electrical properties/price ratio. Due to a large amount of these batteries sold every year they are a considerable secondary source of zinc and manganese. A hydrometallurgical method of recovering those metals seems to be attractive. In this paper leaching tests have been presented to evaluate the leaching behavior of Zn and Mn and their compounds of interests under different conditions such as solid/liquid ratio (weight of sample/leaching solution volume), sulfuric acid concentrations, temperature and time of leaching. The acid concentration was investigated in the range of 0.2 to 5.0 M and the leaching time was from 30 minutes to 5 hours. The tests were carried out in temperature range of 20 – 80oC. It was shown that the leaching recovery of zinc and manganese increases with increasing sulfuric acid concentration up to 2.0 M and zinc is dissolved under these conditions, whereas only around 50% of manganese is recovered. It was found that the rate of zinc leaching is higher than that of manganese and the rate of both reactions is increasing with temperature as well as with a decrease of the solid/liquid ratio.