Modeling and Optimization of Manganese Carbonate Precipitation Using Response Surface Methodology and Central Composite Rotatable Design

Abstract

A sulfate solution containing 1773.965 mg/L Mn²⁺, 3216.178 mg/L Mg²⁺ and 566.254 mg/L Ca²⁺ was used to perform the maximum recovery of manganese and minimum recovery of magnesium. Carbonate precipitation was used due to the better selectivity for manganese over magnesium and other impurities recovery compared to hydroxide precipitation. Four factors were studied: solution pH value, contact time, reaction temperature and sodium carbonate consumption. Analysis of variance (ANOVA) and response surface methodology (RSM) were used to determine the optimum. Under the optimum conditions, the manganese and magnesium recoveries were the highest and the lowest respectively, while the pH, the time, the temperature and the volume of Na₂CO₃ were the lowest.  The values of the four factors were found as followed: 8.9293, 60.69 min, 77.95°F, and 50.7650 mL respectively. Moreover, the recoveries of manganese and magnesium were 99.9799% and 4.3045% respectively. The results show that optimization using RSM is effective in improving carbonate precipitation of manganese.