Ferro Silicon Smelting silicon iron
The reducing agent of smelting silicon iron mostly USES metallurgical coke. Metallurgical coke in the coking process in the coking temperature of about 1100 ~ 1300 ℃ and form of coke, so also known as metallurgical coke of high temperature coke or burn. Carbonization temperature of about 600 ~ 800 ℃ and formed coke called focal or carbocoal in low temperature. Coal gas coke is a kind of low-temperature coke, which is a by-product of gas production.
The properties of coke and metallurgical coke are as follows:
1. The resistance
The relationship between the resistance and the temperature is the relationship between the resistance and the temperature, as shown in figure 4. The resistance of gas coke is greater than that of metallurgical coke, and even at higher temperature, its resistance is greater than that of metallurgical coke. The important advantages of high resistance gas coke. It is proved by practice that partial gas coke is used in the smelting of silicon iron and the electrode can be inserted into the furnace to reduce the power consumption.
2. Chemical composition
It can be seen from table 4 that the coal gas coke contains low carbon and higher ash content, which is not as good as metallurgical coke. This is caused by the low coking temperature of the gas coke. Low carbon content, gas coke for it as a reductant addition amount should be more, at the same time because of high ash content in coal gas coke, smelting slag quantity increases, on the other hand is also due to the low carbon in the coke gas and its poor mechanical strength. In smelting, there are usually carbon deficiency in crucible and lower part. It can be seen that smelting silicon iron is used for reducing agent with gas coke, and the furnace condition is not easy to maintain.
3. Porosity and reactivity
Coke gas porosity is larger than the metallurgical coke porosity of 40 ~ 60 ﹪, such not only make the coke gas resistance is big, but also expand the interface reaction, gas coke reaction ability are also high on the other hand, are favorable reaction speed.
Cost of 4.
The price of gas coke is 10 ~ 20 percent lower than that of metallurgical coke.
The smelting silicon iron is generally used for mining furnace and continuous operation method.
The so-called continuous operation method is that after the furnace is subjected to high temperature, it constantly reacts and melts, and the material surface drops accordingly. At the same time continuously add new furnace material, the furnace in the furnace is always full. According to the melting of the furnace, the amount of alloy is regularly released. During the whole process of the smelting process, the electrode is inserted deep inside the furnace, without exposing the arc, so the heat loss is low and the furnace temperature is high.
Because of these characteristics of silicon iron smelting, the whole process of smelting is not in stages, this method is called continuous operation method.
In addition, it is also useful to smelt silicon iron in blast furnace. However, due to its low furnace temperature, the product contains about 10 ~ 20 percent silicon, and it is generally not used to smelt silicon iron in blast furnace.