What Is The Production Method Of Silicon Calcium Alloy

Silica-calcium alloy is prepared by reducing silica and calcium oxide with carbonaceous reducing agent in a reduction furnace. There are two smelting methods, namely: one-step method and two-step method.
One step method is to load the lime, silica and carbonaceous reducing agent, which are well weighed and evenly mixed, into the electric furnace, and use the appropriate process operation to refine the silicon calcium alloy. One step production of silicon calcium alloy, there are two feeding methods, one is mixed feeding method, one is layered feeding method.
1, mixed feeding method
The operation of the mixed charging method is similar to the operation of the small electric furnace to produce 75% ferrosilicon, but the silica-calcium alloy charge is not all mixed into the furnace, but some of it is in the form of partial charging, and 1/4 to 1/3 of the silica is added to the electric level after the falling of the material, and the wood block is added separately, and the rest of the silica and lime, coke, and bituminous coal are mixed into the furnace.
2, layered feeding method
The layered feeding method is to mix lime with the corresponding amount of coke (according to the coke required to generate low-grade calcium carbide) and concentrate it into the furnace, after it is cleared, silica and the remaining reducing agent are mixed and then added. The operation process of the layered feeding method can be divided into three stages:
1) It is the temperature raising stage. After iron production, the temperature in the furnace decreases, so it must be raised. Its operation is: discharge level after iron, ramming furnace, taking out hard blocks, finishing the material surface, piercing and breathable, strengthening the material surface maintenance, giving full load, deep plug level, this stage is generally 1 hour and 20 minutes.
2) The generation stage of CaC2. When the temperature in the furnace increases, remove the floating material around the electric stage, pick up the viscous material, quickly mix the added lime and the corresponding reducing agent, all directly added to the orange vortex around the electric stage. In order to accelerate the generation of CaC2, we should try to give full load and strive for early capping material. The duration of this stage is generally 30-40 minutes, and cannot be too short or too long. The time is too short, the CaC2 is not sufficient, and a large amount of CaO that does not participate in the reaction will react with SiO2 added later into salt. Too long, calcium volatilization and heat energy loss increase, alloy Ca content decreases, unit power consumption increases.
3) It is the stage of destroying CaC2 with silica to form CaSi alloy. After CaC2 is generated, the mixture is added, and SiO2 in the mixture is used to destroy CaC2 and generate CaSi alloy. After adding the material, cook it until it comes out.
The following operation should be evenly fed, carefully maintain the furnace condition, increase the permeability of the material surface, ensure that the electric level is deeply and steadily inserted into the charge, prevent the collapse of the material from burning, so as to reduce the volatilization and heat loss of Ca. The smelting time at this stage is generally 2.5-3 hours.
The duration of this phase should not be too long or too short. Too long, the volatilization and heat loss of Ca increase, the alloy contains low Ca, the unit power consumption increases; Too short, a large amount of CaC2 and SiO2 do not fully react, the amount of slag increases, the calcium in the alloy is low, and the amount of silicon and calcium generated is small.
Iron and alloy casting, normally every 4-5 hours out of the furnace. When drawing iron, use round steel or burners to open the outlet, and hot metal and slag flow into the tundish at the same time. Because the slag density is greater than the alloy density, the alloy must stay in the slag separator for 2-4 minutes, and after the alloy is completely raised, the alloy is slowly poured into the ingot mold. When it is found that the alloy surface is white and shiny, the casting is stopped immediately to avoid the alloy slag inclusion. After condensation, the alloy is demoulded and finished in storage.