Ferrochromium Extraction Method

Medium, low and micro-carbon ferrochromium generally uses silicon-chromium alloy, chromite and lime as raw materials, and is refined and desiliconized with a 1500-6000 kVA electric furnace, and is operated with high basicity slag (CaO/SiO2 is 1.6-1.8). Low and micro-carbon ferrochromium is also produced on a large scale by the hot mixing method. During production, two electric furnaces are used, one for smelting silicon-chromium alloy, and the other for melting slag composed of chromium ore and lime. The refining reaction is carried out in two buckets in two stages: ① After the slag of the slag furnace is injected into the first bucket, the silicon-chromium alloy that has been initially desiliconized in the other bucket is added. The amount is very large, and the desiliconization is sufficient, and the micro-carbon ferrochromium with a silicon content of less than 0.8% and a carbon content of as low as 0.02% can be obtained. ②After the slag (containing about 15% of Cr2O3) after the reaction in the first bucket is moved to the second bucket, the silicon-chromium alloy (containing 45% of silicon) made by the silicon-chromium electric furnace is heated into the slag to react. After that, the silicon-chromium alloy (containing about 25% silicon) that has been initially desiliconized is obtained, which is mixed into the first ladle for further desiliconization, and the slag containing Cr2O3 less than 2-3% can be discarded.

Refining medium and low carbon ferrochromium by oxygen blowing method, using liquid carbon ferrochromium as raw material, adding a small amount of lime and fluorite to the molten pool during blowing to make slag, and adding silicon-chromium alloy or ferrosilicon before tapping to recover the slag. chromium. The blowing of micro-carbon ferrochromium is only possible under a certain degree of vacuum.

Refining by vacuum solid-state decarburization method, using ground high-carbon ferrochrome as raw material, part of the ground high-carbon ferrochrome is oxidized and roasted as an oxidant, mixed with water glass or other binders, pressed into agglomerates, and subjected to low temperature After drying, in a car-bottom vacuum furnace, heating and reducing at a vacuum degree of 0.5-10 mmHg and a temperature of 1300-1400 °C for 35-50 hours, micro-carbon with a carbon content of less than 0.03% or even less than 0.01% can be obtained. Ferrochrome.