High carbon ferromanganese use and production process (2)

Update: 28-03-2020

Electric furnace method There are three methods for sme […]

Electric furnace method
There are three methods for smelting high-carbon ferromanganese by the electric furnace method.
1) Flux-free method. For manganese-rich ore with high manganese oxide, the flux-free method can be used to smelt ferromanganese. The smelting furnace is not equipped with lime, the equipment and operation are similar to ferrosilicon, and acid slag operation is used under the condition of insufficient reducing agent. It is about 1320 ~ 1400 ℃ lower than the flux method. In this method, it is necessary to obtain qualified high-carbon ferromanganese and low-phosphorus and low-iron manganese-rich slag containing more than 35% manganese for smelting manganese alloys. The distribution of manganese at this time is as follows: the alloying rate is 58% ~ 60%, the slag entering rate is 30% ~ 32%, and the volatilization is 10%. Obviously, smelting of high-carbon ferromanganese by the fluxless method must use manganese-rich ore containing high manganese, and requires a relatively low phosphorus content in the ore. Although the recovery rate of manganese is low in this method, most manganese can be recovered when smelting manganese alloys with manganese-rich slag, and the total recovery rate of manganese is higher than that of flux. The solvent-free smelting process of high-carbon ferromanganese is continuous. The furnace charge is continuously added to the furnace during the melting process. The batch can be composed of 300 kg of manganese ore, 60 to 70 kg of coke, and 15 to 20 kg of steel scrap. When solvent-free smelting, the unit power consumption of the product is very low, and low-silicon high-carbon ferromanganese is easy to produce, because most of the silicon is concentrated in the slag.
2) Solvent method. Solvent method is a commonly used method for smelting high-carbon ferromanganese. In addition to manganese ore and coke in the composition of the furnace charge, high alkalinity slag is used to operate the alkalinity during lime and smelting, B = 1.3 ~ 1.4. Using sufficient reducing agents, the manganese content in the waste slag has been minimized and the recovery rate of manganese has been improved. This method is used to smelt high-carbon ferromanganese with lean and rich manganese ore, and this method will be discussed in detail later.
3) Less solvent method. This method uses a so-called "weak acid slag method" between a solvent method and a solventless method. The method is to add a suitable amount of lime or limestone to the furnace charge, and control the ratio of the basicity m (CaO) / m (SiO2) or m (CaO + MgO) / m (SiO20) of the slag between 0.6 ~ 0.8, thereby It can not only improve the recovery rate of manganese, but also obtain slag containing 25% ~ 30% of manganese and appropriate amount of CaO. Mixing this slag into the charge of smelting silicon-manganese alloy can save lime and reduce lime deliquescence. Increased amount of charge dust, thereby improving the permeability of the charge. Most of the high-carbon ferromanganese smelted in electric furnaces abroad adopts the solventless method and the less acid method. In the 1950s, China also used the flux-free smelting method to produce 76% 80% manganese-carbon ferromanganese from manganese-rich ore containing 46% to 47% manganese, and also obtained manganese-rich slag containing 35% to 40% manganese. . However, due to the large amount of manganese-depleted ore in China, the solvent method or a small amount of solvent method is currently used.