749470619 Cobalt precipitation with MgO

This chapter discusses the cobalt precipitation process employed in the Kolwezi Tailings project, focusing on the transition from co-solvent extraction to the use of magnesium oxide (MgO) as the primary precipitant. The objective was to optimize cobalt transfer into the electrowinning (EW) circuit while addressing environmental concerns related to waste byproducts. Methodologically, limited laboratory tests were conducted to assess the efficacy of MgO in cobalt precipitation, followed by a continuous mini plant campaign at Mintek which utilized synthetic solutions mimicking conditions from an upstream copper circuit. Results indicated that MgO presented significant advantages over traditional methods, such as reduced Ca scaling and a smaller final mass of solids, though it also posed challenges related to cost and increased magnesium deportment into the EW circuit. This chapter provides a detailed examination of the laboratory and pilot plant findings, highlighting the operational characteristics and operational constraints of the cobalt precipitation unit operation.