The process of electrolytic manganese metal production is mainly divided into two stages:
(1) Preparation of electrolytic solution. Manganese ore powder is used to react with inorganic acid, and the manganese salt solution is heated, while ammonium salt is added to the solution as a buffer, iron is removed by oxidising and neutralising with oxidising agent, and heavy metals are removed by sulphurising and purifying agent, and then it is filtered and separated, and electrolytic additives are added to the solution as the electrolytic solution. At present, industrial production widely adopts the method of leaching manganese in sulphuric acid to produce electrolyte, and the method of producing manganese metal by electrolysis of manganese chloride salt solution has not yet formed large-scale production.
The manganese ore powder used in the production of manganese sulphate is divided into two kinds of manganese ore: rhodochrosite and soft manganese ore.
The main chemical reaction for the production of manganese sulphate from manganese rhodochrosite powder is:
MnCO3+H2SO4→MnSO4+CO2↑+H2O
To produce manganese sulphate from soft manganese ore, the soft manganese ore is firstly reduced and roasted, reduced to manganese monoxide, and then leached with sulphuric acid, and its main chemical reaction is:
MnO+H2SO4→MnSO4+H2O
(2) Electrolysis operation process. Inject manganese sulphate water-soluble electrolyte containing ammonium sulphate into the isolated electrolytic tank, connect direct current, produce electrodialysis, precipitate manganese metal on the cathode plate, and precipitate oxygen on the anode plate; periodically replace the cathode plate, and treat the electrodialysis products with passivation, washing, drying, stripping and so on, and then obtain manganese metal products.
