Generally, low-carbon ferrochromium is made of silicon-chromium alloy, chromite and lime, and it is refined and desiliconized by 1500 ~ 6000 KVA electric furnace, and the slag with high alkalinity (CaO/SiO2 _ 2 is 1.6 ~ 1.8) is operated. Low-carbon and micro-carbon ferrochromium are also produced on a large scale by hot mixing method. In production, two electric furnaces are used, one for melting Si-Cr alloy and the other for melting slag composed of chrome ore and lime. The refining reaction is carried out in two stages in two barrels: ① After the slag of the slag furnace is poured into the first barrel, the silicon-chromium alloy which has been preliminarily desilicated in the other barrel is added. Due to a large amount of excess slag oxidant and sufficient desilication, micro-carbon ferrochrome with silicon content less than 0.8% and carbon content as low as 0.02% can be obtained. (2) After the slag (containing about Cr2O3 15%) reacted in the first barrel is moved to the second barrel, the silicon-chromium alloy (containing 45% silicon) melted in the silicon-chromium electric furnace is hot mixed into the slag, and after the reaction, the preliminarily desiliconized silicon-chromium alloy (containing about 25% silicon) is obtained, which is mixed into the first barrel for further desiliconization, and the slag contains less than 2-3% Cr2O3.
Refining medium-low carbon ferrochrome by blowing oxygen, using liquid ferrochrome as raw material, adding a small amount of lime and fluorite to the molten pool during blowing, adding silicon-chromium alloy or ferrosilicon before tapping, and recovering chromium from the slag. The blowing of micro-carbon ferrochromium is only possible under a certain vacuum.
Vacuum solid-state decarburization refining takes ground high-carbon ferrochromium as raw material, and a part of ground high-carbon ferrochromium is used as oxidant after oxidation roasting, which is mixed with water glass or other binders, pressed into green blocks, dried at low temperature, and placed in a vehicle bottom vacuum furnace with a vacuum degree of 0.5- 100 mm Hg and a temperature of 1300- 1400℃.