TITLE:
Reclamation of Mercury from Used Silver Oxide Watch Batteries
AUTHORS:
Natarajan Sathaiyan
KEYWORDS:
Used Silver Oxide-Zinc Watch Batteries; Leaching; Zinc Dust; Cementation; Mercury
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.4 No.1,
January
8,
2014
ABSTRACT:
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.