Calcium silicon is a good deoxidizer and desulfurizer, mainly used for deoxidation. Silicon calcium alloy is a binary alloy of silicon and calcium with very little iron. With the development of continuous casting and out-of-furnace ladle refining, the consumption of calcium-silicon alloys has increased rapidly. There are two production methods for silicon calcium alloys: the one-step method and the two-step method.
The one-step method is to produce a silicon-calcium alloy by reducing silica and lime with carbon in an electric furnace;
The two-step method is to produce calcium carbide (or high carbon ferrosilicon) in one electric furnace first, and then use calcium carbide, silica and coke (or use high carbon ferrosilicon and lime) to produce calcium silicon in another electric furnace alloy.
The one-step method is divided into a mixed feeding method and a layered feeding method. The mixed feeding method is to add silica, lime and coke together into the reduction electric furnace. Simultaneous reduction of CaO and SiO2 with carbon results in a calcium-silicon alloy. The purpose is to reduce the contact between calcium oxide and silica to reduce the formation reaction of Cao-SiO2. The layered feeding method is to first add lime and coke (the amount added is calculated according to the reaction of generating calcium carbide) near the electrode, and after melting, let CaO generate as much CaC2 as possible, and then mix the silica and the remaining carbon into the furnace to produce Silicon calcium alloy.
There are two two-step methods. One is to produce lime and calcium carbide from lime and coke in one electric furnace firstly, and then crush calcium carbide together with coke and silica to produce silicon-calcium alloy in another electric furnace. The first is to produce high-silicon ferrosilicon in an electric furnace, and then use high-silicon ferrosilicon as a reducing agent to reduce calcium oxide in an electric furnace to obtain a silicon-calcium alloy.