Effects of additives on nickel electrowinning from sulfate system
(School of Chemical Engineering, Sichuan University, Chengdu 610065, China)
Abstract: In order to eliminate the pitting and improve the surface morphology of cathode nickel, the influence of additives of boric acid and dodecyl sodium sulfate (SDS) on the process of nickel electrowinning from sulfate system was studied by cathode polarization tests and nickel electrodeposition experiments. The experimental results show that the addition of boric acid can increase the cathode polarization while SDS can decrease the cathode polarization. Both boric acid and SDS are useful to eliminate the pitting on nickel deposits and improve the morphology of surface. Good deposit morphology with rare pitting and high current efficiency is favored by adding 10 g/L boric acid and 40 mg/L SDS in the electrolyte under the condition of nickel ion concentration of 80 g/L, sodium ion concentration of 10 g/L, pH of 3, current density of 220 A/m2 and temperature of 70 ℃.
Key words: nickel electrowinning; sulfate system; boric acid; dodecyl sodium sulfate; pitting; cathode polarization