Behaviour of cobalt during precipitation of manganese from the NH 3(NH 4) 2SO 4MnO 2 system

Abstract

A detailed study was made on cobalt losses during precipitation of manganese from the NH 3(NH 4) 2SO 4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 NH 3; 80 gl −1 (NH 4) 2SO 4; pO 2 51–203 kPa; temperature 348K. Under these conditions the manganese content of the precipitated compound varied between 64% and 70%.