Behaviour of cobalt during precipitation of manganese from the NH3-(NH4)(2)SO4-Mn-O-2 system

A detailed study was made on cobalt losses during precipitation of manganese from the NH3-(NH4)(2)SO4-O-2 system. Various parameters were changed during this study: the concentration of ammonia and ammonium sulphate; oxygen partial pressure; precipitation time; and temperature, It was found that cobalt losses were maximum at room temperature in the absence of ammonium sulphate, At 348K about 4% cobalt loss, with 0.75 mg l(-1) manganese remaining in solution, was obtained. The linear and interaction parameters were quantified for cobalt loss and manganese in the precipitate using a 2(3) factorial optimisation technique, About 0-4% cobalt loss with 0.55-3 mg l(-1) manganese remaining in solution could be obtained under the following conditions: 20-60 gl(-1) NH3; 80 gl(-1) (NH4)(2)SO4; pO(2) 51-203 kPa; temperature 348K. Under these conditions the manganese content of the precipitated compound varied between 64% and 70%.