Electrolyte parameter effects in the electrowinning of nickel from sulfate electrolytes

Nickel deposits were electrowon from acid sulfate electrolytes to determine the effects of various parameters when buffer agents were not present. The nickel concentration, pH and temperature of the electrolyte were varied over a relatively broad range to evaluate changes in cathode morphology and current efficiency. Both good qualify deposits, ones which were flat, smooth and ductile, and degraded deposits, which were characterized by cracking, curling, pitting and brittleness, were obtained depending on the conditions chosen for these three variables. A good quality deposit morphology and a high current efficiency were favored by high nickel concentrations and electrolyte temperatures. The deposit morphology was improved at lower pH, but a decrease in deposit current efficiency resulted Deposit orientations were determined but no specific trends were evident. Cyclic voltammetry tests did show some correlation to deposit morphology but not to current efficiency. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.