Extraction method of ferrochrome

Medium, low, and micro-carbon ferrochrome generally is generally made of silicon-chromium alloy, chromite and lime. The desilication is refined in an electric furnace with 1500~6000 kva and operated with high basicity slag (CaO/SiO2 is 1.6~1.8). Low – and micro-carbon ferrochrome is also produced by heat mixing on a large scale. Two electric furnaces are used in production, one to smelt the silicon-chromium alloy and the other to melt the slag composed of chromium ore and lime. The refining reaction is carried out in two stages in two buckets: (1) After the slag of slag furnace is injected into the first bucket, the silicon chromium alloy which has been preliminarily desilicated in the other bucket is added. Due to the large surplus of oxidant in slag and sufficient desilication, the micro-carbon ferrochrome with silicon content less than 0.8% and carbon content less than 0.02% can be obtained. (2) The first bucket after the reaction slag (containing about 15% Cr2O3) moved to the second bucket, the silicon chromium alloy (containing 45% silicon) made in the silicon chromium electric furnace is hot mixed into the slag, after the reaction to get a preliminary desilication of silicon chromium alloy (containing about 25% silicon), mixed into the first bucket for further desilication, the slag containing Less than 2~3% Cr2O3 can be abandoned.

Oxygen blowing method refining medium and low carbon ferrochrome, using liquid carbon ferrochrome as raw material, blowing into the molten pool to add a small amount of lime, fluorite slag, before adding silicon chromium alloy or ferrosilicon to recover the chromium in the slag. The blowing of micro – carbon ferrochrome is possible under a certain vacuum.

Vacuum solid decarburization refining, using finely ground high carbon ferric chromium as raw material, which is a part of the finely ground high carbon ferric chromium oxide roasting as an oxidant, with water glass or other adhesive, pressed into a mass, after low temperature drying, in the car type vacuum furnace, in the vacuum degree of 0.5~10 mm hg, temperature 1,300~1,400℃ heating reduction 35~50 hours. Micro-carbon ferric chromium with carbon content less than 0.03% or even less than 0.01% can be obtained.