China Nonferrous Metallurgy

In view of the complicated calcium removal process, high energy consumption and high cost in the current sulfuric manganese solution purification, this paper explores the method of removing calcium ions from the solution using P204 extraction. Based on the determined aqueous phase pH value, the study examines the effects of P204 saponification rate, reaction temperature, mixing time, P204 volume concentration, and extraction grade on the Ca concentration in the aqueous phase, and concludes the following main conclusions. The actual extraction reaction endpoint pH value is lower than the optimal pH value by 2.5 to 3.0, and the pH value needs to be maintained above the optimal value during the extraction process by adjusting the saponification rate of the organic phase. The optimal extraction process parameters are P204 saponification rate of 10%, system temperature of 35℃ or above, mixing time of 4 minutes or more, P204 volumetric concentration of 20%, and extraction grade of more than 41, under which the Ca content in the aqueous phase meets the requirement of HG/T 4823—2015 Battery Grade Sulfuric Manganese (i.e., ω_Ca≤0.01%, ω_Mn∶ω_Ca≥3200), and the method avoids the introduction of fluoride ions and eliminates the interference of fluoride ions on subsequent processes. At the same time, it greatly reduces the use of acid and alkali, achieving low-cost purification of sulfuric manganese solution, and has great promotion value.