Ferro Chrome (FeCr) is an alloy of chromium and iron containing 50% to 70% chromium by weight. Ferrochrome is produced by electric arc carbothermic reduction of chromite.
With the massive mining of global chromium ore resources, high-quality lump ore resources are becoming less and less, and the lean chromium ore is fine ore after beneficiation; but when smelting high-carbon ferrochrome in submerged arc furnaces, too much fine ore will cause the furnace charge to breathe The performance becomes worse, the furnace condition deteriorates, which seriously affects the technical and economic indicators such as safety and power. Consumption and Chromium Production. Therefore, the current mainstream equipment fully enclosed submerged arc furnace cannot directly smelt fine ore. Therefore, the development of a new high-carbon ferrochrome smelting process plays a vital role in reducing coke powder consumption and smelting power consumption, improving chromium yield and market competitiveness.
At present, the internationally accepted chromium ore powder processing and smelting processes mainly include the methods of chrome ore powder ball roasting (Outokumpu), SRCand DRC.
The chromium ore powder roasting method (Outokumpu) adopted by high-carbon ferrochrome first grind the chromium ore powder, filter and dehydrate, mix the mineral powder filter cake with bentonite to form pellets, and then send them into the double furnace shell shaft for the baking used stove. The finished chromium ore is pellets, coke, and silica, which are sent to the rotary kiln on the top of the submerged arc furnace for preheating, and then enter the closed submerged arc furnace for smelting. The hot charging temperature of the submerged arc furnace is low (450~550°C), and the physical sensible heat cannot be effectively utilized. The power consumption of smelting is higher than that of the methods of SRC and DRC, and the power consumption of smelting is about 800kwh/t ferrochrome; the block roasting process is carried out in an oxidizing atmosphere without pre-reduction function, resulting in the smelting of a large amount of coke in submerged arc furnaces.
Both the SRC and the DRC methods of high-carbon ferrochrome are pellet pre-reduction methods. Their main feature is to pre-reduce the smelting process of the submerged arc furnace, and the pellets are pre-reduced before entering the submerged arc furnace. The main difference is that the SRC method uses a rotary kiln as a pre-reduction device, and the DRC method uses a rotary hearth furnace as a pre-reduction device. Using a rotary hearth furnace for pre-reduction can avoid problems such as ringing and pulverization of the rotary kiln, and effectively improve the quality of pellets and production operations. rate, adopting regenerative combustion technology, the temperature in the furnace can be increased to 1400~1450°C, which can effectively improve the reduction rate of chromium (Cr).