Reclamation of Mercury from Used Silver Oxide Watch Batteries

摘要

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 Hg2+ 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℃ 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.