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The process of galvanisation of steel generates zinc ash as the waste product, thus creating pollution problems. The recovery of zinc metal from zinc ash, with a zinc content of about 76% by leaching and electrowinning has been studied. The presence of chloride has been identified as the major problem area. A catalytic anode based on iridium dioxide (IrO 2 ) was used as the anode material to overcome this problem. Catalyst loading was kept at an economically acceptable level. The catalyst's stability, energy consumption and efficiency of zinc recovery are discussed. The service life of the IrO 2 active coating has been established by an accelerated polarisation test. The zinc deposit recovered from the zinc ash has been examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

This paper deals with the reclamation of mercury from the used silver oxide quartz wristwatch batteries employing leaching-cementation technique. The used batteries are first crushed to liberate the encapsulated active material from the case which is leached in nitric acid to bring all metal contents into solution. After the removal of silver in the solution as silver chloride by precipitation, the mercury which is present as Hg 2+ in the solution has been reclaimed through cementation with zinc dust. Various effects like zinc sheet and dust, zinc quantity, pH of the solution, duration and temperature have been carried out to standardise the conditions for maximum mercury reclamation. At a temperature of 45˚C and at 3.9 pH, 92.3% of mercury was recovered using 74 µm size zinc dust with purity greater than 99.78% and the same is characterized by XRF and the results are discussed.

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