Ferromanganese In Steelmaking

In steelmaking, ferromanganese is used as a deoxidizer and alloy additive, and is the most widely used ferroalloy. The manganese ore used to smelt ferromanganese is generally required to contain 40-50% manganese, the ratio of manganese to iron is greater than 7, and the ratio of phosphorus to manganese is less than 0.003. Before smelting, the manganese carbonate ore is first roasted, and the fine ore is sintered into agglomerates. Ores with high iron and phosphorus content can only be used in combination, or manganese-rich slag with low iron and phosphorus content can be obtained through selective reduction. Coke is used as a reducing agent during smelting, and lean coal or anthracite is also used in some factories. The auxiliary raw material is mainly lime, and silicon dioxide is generally added when smelting manganese-silicon alloy.


The international general standard for carbon ferromanganese is 75-80% manganese. In order to adapt to the low-grade raw material conditions of manganese ore, my country has stipulated grades with lower manganese content (electric furnace ferromanganese contains more than 65% manganese, and blast furnace ferromanganese contains more than 50% manganese). In the past, blast furnaces were mainly used to smelt carbon ferromanganese pellets. With the development of the electric power industry, the use of electric furnaces has gradually increased. At present, blast furnaces are mainly used in Western Europe and China, electric furnaces are used in Norway and Japan, and electric furnaces are also used in new ferromanganese plants in the Soviet Union, Australia, Brazil, and other countries. There are two types of reduction smelting of ferromanganese: the flux method (also known as the low manganese slag method) and the no flux method (the high manganese slag method). The principle of the flux method is the same as that of blast furnace smelting, except that electric energy is used instead of coke for heating. Manganese loss is reduced by adding lime to form high alkali slag (CaO/SiO2 1.3-1.6). The flux-free smelting method does not add lime to form low-iron, low-phosphorus, manganese-rich low alkalinity (CaO/SiO2 is less than 1.0), high manganese slag.

The production methods of high-carbon ferromanganese include the blast furnace method and the electric furnace method.

High-carbon ferromanganese was first produced by the blast furnace, with high output and low cost, and it is still widely used at home and abroad.

The blast furnace method is to add manganese ore, coke, lime, and other raw materials into the blast furnace for smelting to obtain blast furnace ferromanganese containing 52% to 76% of manganese and 0.4% to 0.6 phosphorus. Since the difference between the blast furnace and the electric furnace for smelting high-carbon ferromanganese lies in the different heat sources, the structure, geometry, and operation methods of the two furnaces are different, but the principle of the two furnaces for smelting high-carbon ferromanganese is the same.

However, the two furnaces use the same manganese ore to smelt the phosphorus content of the products. The phosphorus content of blast furnace products is slightly higher than that of electric furnace products by 0.07%~0.11%. This is because the amount of coke in the charge composition of blast furnace smelting is 5-6 times that of electric furnace smelting, so more phosphorus in coke is transferred to the alloy, and the furnace temperature is lower during blast furnace smelting, so the volatilization of phosphorus in the smelting process is higher than that of electric furnace about 10% lower.


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