Cobalt Dissolution from Concentrate in Sulfuric Acid-Ferrous Sulfate System: Process Parameters Optimization by Response Surface Methodology (RSM)

摘要

This study is dedicated to exploring the effect of pH, leaching time, ferrous sulfate amount, temperature, as well as their interaction on the dissolution of cobalt by response surface methodology. The ferrous sulfate was used as an effective reducing agent for the dissolution of heterogenite, which constitutes the main cobalt mineral found in Congolese Copperbelt, and the experiments conducted were based on central composite design. Analysis of variance was carried out to study the effects of the individual variable as well as their combined interactive effects on the recovery of cobalt. The optimum process conditions for the cobalt recovery were determined by a desirability function. The results showed that the amount of ferrous sulfate, leaching time, and leaching temperature were statistically significant as independent linear terms. The results also revealed that the interaction of leaching time and the amount of ferrous sulfate has an important effect on cobalt dissolution. The optimal cobalt recovery was 95.79% at the leaching time of 104.48 min, pH of 1.87, amount of ferrous sulfate of 14.9 g, and temperature of 54.8 degrees C, while the experiment of validation at these optimum conditions gave the cobalt recovery of 93.82%. This testifies on the goodness of the model developed in this work, thus, verifying that the model is suitable and fits the experimental data with a reasonable error.