Extraction of Manganese
Prior to the use of electric arc furnace, ferromanganese was produced in mini blast furnace. But the composition was not controlled properly in the blast furnace. High grade ferroalloys are produced by adjustment the composition in the blast furnace. Quality control and adjustment of composition is far better in the submerged electric arc furnace. Sometimes good quality coke is not available for production of quality ferroalloys. In this case, Ferro coke is used for producing ferroalloys. Ferro coke is produced from friable iron ore and low grade coal.
Manganese is mainly produced in the form of ferromanganese and silicomanganese. But these alloys can not be used for producing non-ferrous alloys. Production of non-ferrous alloys requires rigorous control of composition. Pure manganese is used for producing non- ferrous alloys and compounds of manganese. Manganese is produced by electrolytic method. In this method, the purity of manganese is maximum. Low grade manganese ore is used in electrolytic method. Manganese produced by this method are free from impurities. So, it can be used for special steel, coinage alloys, manganese brass and manganese bronze. The electrolyte used for extraction is combination of manganese sulphate, ammonium sulphate and sulphur dioxide. The manganese ore is crushed and cleaned. The crushed ore is reduced to manganese oxide. The reduction of ore is carried out by producing producer gas and ore in a rotary kiln. Slowly, oxygen is removed. The reduced ore is leached with electrolyte with brick lined leach tank. Calcine is added to the leaching tank. The electrolyte is agitated. Slowly, the impurities are precipitated and separated out. The remaining electrolyte is shifted to a specially designed cell. The electro refining process is carried out. Slowly, manganese metal is deposited at the cathode end. In this case, the anode is prepared from lead and the cathode is prepared from stainless steel. The manganese that is deposited at the cathode end is collected and cleaned for future use.