Introduction
China is one of the leading iron and steel producing countries in the world and its output of both iron and steel has increased rapidly in the past few decades. One of the important raw materials used in the production of iron and steel is coking coal, which is used to produce coke in blast furnaces. As a result, the quality of coking coal is an important factor influencing the production and quality of iron and steel. There are some major quality indicators of the coking coal used in some large blast furnaces in China.
Moisture Content
Moisture content of coking coal is one of the main quality indicators for blast furnace coke. Too little water can lead to defects in coke structure, e.g., macrospores, honeycombs and bad perforation. Too much moisture content can cause the carbonization rate to decrease, resulting in a decrease in coke strength and poor permeability. Therefore, moisture content should be strictly controlled. In China, the moisture content of coking coal used in large blast furnaces should be no more than 8%.
Ash Content
The ash content of coking coal is another major quality indicator. Too much ash can lead to increased porosity in the coke and decreased strength. In addition, too high an ash content can increase the volatilization of the coking coal during the carbonization process, thus reducing the efficiency of the coke making. The ash content of coking coal used in large blast furnaces in China should not exceed 10%.
Volatile Matter
Volatile matter is another critical factor influencing the quality of coking coal. Too high a volatile matter content can reduce the fixed carbon content and calorific value of the coking coal. It can also increase the susceptibility of the coke to combustion and reduce its strength as well as its Coke oven gas yield during the carbonization process. The volatile matter content of coking coal used in large blast furnaces in China should not exceed 18%.
Sulfur Content
Sulfur content is another critical quality indicator of coking coal. Too much sulfur can lead to the generation of large amounts of sulfur dioxide during the smelting process, which can lead to environmental pollution and health problems. In addition, it can cause slag to become sticky and can produce harmful gases and corrosive liquids in high temperature air, thus reducing the working life of the blast furnace. The sulfur content of coking coal used in large blast furnaces in China should not exceed 0.8%.
Fixed Carbon Content
Fixed carbon content is another important factor influencing the quality of coking coal. Too high a fixed carbon content can lead to decreased coke strength, while too low a fixed carbon content can lead to decreased calorific value. The fixed carbon content of coking coal used in large blast furnaces in China should be between 45% and 55%.
Conclusion
In conclusion, coking coal is a critical raw material in the production of iron and steel, and its quality is an important factor influencing the production and quality of iron and steel. There are some major quality indicators of coking coal used in some large blast furnaces in China, including moisture content, ash content, volatile matter, sulfur content, and fixed carbon content. These should be strictly controlled to ensure the production and quality of the iron and steel produced.
