Abstract:

Nickel build-up in copper electrorefining electrolytes remains a recurring operational challenge, adversely impacting cathode quality, current efficiency, and overall process stability. Traditional purification methods, such as evaporative crystallization, are energy-consuming and often yield low-purity nickel sulfate due to impurity co-concentration. As an alternative, this study explores antisolvent crystallization, focusing on the operational parameters that influence nickel recovery. Systematic experiments assessed the effects of antisolvent type, dosage, and mixing intensity under typical tankhouse electrolyte conditions. Among the tested antisolvents, isopropanol produced the highest nickel sulfate recovery, reaching a maximum crystallization yield of 77% at room temperature. Increasing the antisolvent dosage and raising the mixing speed from 50 to 400 rpm accelerated supersaturation development in the Cu–Ni–SO₄ electrolyte system, thereby promoting faster nucleation and increasing overall crystal formation. These results indicate that optimizing the antisolvent type, dosage, and mixing speed can improve the effectiveness and selectivity of nickel removal relative to conventional evaporative purification.

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Ms. Sumin Lee