Pr. Ramachandran et al., ELECTROLYTE ADDITIVES FOR IMPROVED BEHAVIOR OF ANODES IN ELECTROWINNING OF METALS, Transactions of the Indian Institute of Metals, 49(6), 1996, pp. 789-794
Compounds of arsenic, phosphorous and cobalt have been investigated as
additives to the electrolyte for the Improvements of anodes used in t
he electrowinning of metals. Corrosion of lead anodes, anodic depositi
on of PbO2 in lead electrowinning and poisoning of electrocatalytic an
odes are some of the problems discussed. Addition of cobalt salt in sm
all amounts to the electrolyte reduces anodic corrosion of lead anodes
employed in the electrowinning. Corrosion in terms of PbO2 is largely
avoided and instead oxygen evolution is promoted. Anodic formation of
PbO2 from lead fluoborate electrolyte is controlled by the addition o
f soluble compounds of P or As or Co to the electrolyte. Arsenic is fo
und to he more effective even at a concentration of 500 ppm and prefer
ential adsorption of these species on the electrode surface is the pro
bable reason for the inhibition of PbO2 formation. Electrocatalytic an
odes employed for the reduced cell voltage in the electrolytic cells g
et poisoned by the presence of manganese in the electrolyte. Arsenic o
r phosphorous compounds added in small amounts to the electrolyte, eff
ectively controls anodic deposition of MnO2 prolonging the effective u
se of the expensive electrocatalyst employed.