Purification of MnSO4 Solutions

A process for purifying a MnSO4 solution, the process including

• precipitating impurities from the MnSO4 solution
• (i) in the presence of a stochiometric excess of fluoride anions, where said stochiometric excess of fluoride anions is calculated on the basis of the fluoride anions required to react with all Mg2+ and Ca2+ cations present in the MnSO4 solution as impurities to form CaF2 and MgF2, and
• (ii) in the presence of sulphide anions,
• at a pH higher than 4, producing a slurry or suspension comprising a purified MnSO4 solution as a carrier medium and a suspended precipitate which includes MnS, MnF2, CaF2 and MgF2;
• separating the slurry or suspension into said purified MnSO4 solution and said precipitate;
• reacting the precipitate with a SO4 salt (sulfate salt) other than MnSO4 in a solid-state reaction to produce recovered MnSO4 from the MnS and MnF2;
• and
• recycling the recovered MnSO4 to the MnSO4 solution which is being purified, thereby to reduce Mn losses and improve MnSO4 yield.