Coke is a type of solid fuel. It is obtained by dry distillation of coal at a high temperature of approximately 1000°C. Its main component is fixed carbon, followed by ash, and it contains very little volatile matter and sulfur. It is silver-gray and has a metallic luster. It is hard and porous. Its calorific value is mostly 26380 - 31400 kJ/kg (6300 - 7500 kcal/kg). According to different uses, there are three major types: metallurgical coke, foundry coke, and chemical coke. According to size, there are also lump coke, crushed coke, and coke fines, etc. It is mainly used for smelting steel or other metals, and can also be used as a raw material for the production of water gas, gasification, and the chemical industry.