According to different carbon content, ferrochrome can be divided into high carbon ferrochrome (C < 10%), medium carbon ferro chrome (C < 4.0%), low carbon ferrochrome (C < 0.5%) and micro carbon ferrochrome (C < 0.15%) .High carbon ferrochromium is also called carbon ferrochromium, medium, low and low carbon ferrochromium is also called refining ferrochromium.
There are two main smelting methods of medium carbon ferrochromium: high carbon ferrochromium refining method and electro-silicothermic method.
When high carbon ferrochromium is used in chromium concentrate, the refining slag has higher viscosity and melting point, and the smelting temperature must be higher. Therefore, high power consumption, short lining life, carbon content is not easy to fall. The electro-silicothermic method is to reduce the oxides of chromium and iron with the silicon in the silicon-chromium alloy under the condition of making alkaline slag in the electric furnace, so as to produce medium and low carbon ferrochromium.
Medium-carbon ferrochromium is refined by oxygen blowing method. Liquid ferrochromium is used as raw material. A small amount of lime and fluorite is added to the molten pool to make slag. Silicochromium alloy or ferrosilicon is added before iron is produced to recover chromium from slag. Oxygen blowing of high carbon ferrochromium has great advantages, such as high productivity, low cost and high recovery.
Ferrochrome is mainly used as an alloy additive in steelmaking. In the past, it was added at the later stage of steelmaking. Low and micro-carbon ferrochromium must be used in smelting low-carbon steel such as stainless steel, so the production of refining ferrochromium has been developed on a large scale at one time. Medium and low carbon ferrochromium is used in the production of medium and low carbon structural steel and carburized steel, and in the manufacture of gears, high pressure blower blades and valve plates.