The reducing agent for smelting ferrosilicon is mostly metallurgical coke. Metallurgical coke is a coke formed at a coking temperature of about 1100 to 1300°C during the coking process, so it is also called high-temperature coke or full coke. Coke formed at a coking temperature of about 600 to 800°C is called low-temperature coke or semi-coke. Gas coke is a type of low-temperature coke. The so-called gas coke is a by-product of gas production.
The properties of gas coke and metallurgical coke are compared as follows:
1.Resistance
The relationship between specific resistance and temperature of various cokes with particle sizes of 10 to 15 mm is shown in Figure 4 based on actual measurements. The resistance of gas coke is greater than that of metallurgical coke. Even at higher temperatures, its resistance is still greater than that of metallurgical coke. The important advantage of gas coke is when the resistance is high. Practice has proved that when smelting ferrosilicon, part of the gas coke is used, and the electrode can be inserted deeper into the charge, thereby reducing power consumption.
2.Chemical composition
Gas coke contains lower fixed carbon and higher ash content, and is not as good as metallurgical coke in terms of chemical properties. This is caused by the low coking temperature of gas coke. The carbon content of gas coke is low, and more should be added when using it as a reducing agent. At the same time, due to the high ash content in gas coke, the amount of slag during smelting also increases. On the other hand, due to the low carbon content in gas coke and its Mechanical strength is poor. During smelting, there is often a lack of carbon in and below the crucible. It can be seen that gas coke is used as the reducing agent in ferrosilicon smelting, and the furnace condition is difficult to maintain.
3. Porosity and reaction ability
The porosity of gas coke is 40-60% greater than that of metallurgical coke. This not only increases the resistance of gas coke, but also expands the reaction contact area. On the other hand, the reaction capacity of gas coke is also higher, which is beneficial to speeding up the reaction speed. conduct.
