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In recent years, coke quality has been a concern for steel companies, and reducing the coke ratio is an important way for them to cut costs. Therefore, to correctly evaluate the quality of coke, it is necessary to understand its properties from the following aspects. 1. Definition of coke: Bituminous coal is heated to 950–1050°C in an air-free environment, and through stages such as drying, pyrolysis, melting, bonding, solidification, and contraction, it is ultimately transformed into coke. This process is known as high-temperature coking (high-temperature dry distillation). Coke produced by high-temperature coking is used in blast furnace smelting, casting, and gasification. Coke oven gas, which is recovered and purified during the coking process, serves as both a fuel with high calorific value and an important raw material for the organic synthesis industry. Metallurgical coke is a general term for blast furnace coke, foundry coke, ferroalloy coke, and coke used in non-ferrous metal smelting. Since over 90% of metallurgical coke is used in blast furnace ironmaking, blast furnace coke is often referred to as metallurgical coke. Casting coke is coke specifically used for melting iron in cupola furnaces. Casting coke is the main fuel for melting iron in blast furnaces. Its function is to melt the charge and superheat the molten iron, as well as to support the charge column and maintain its good air permeability. Therefore, cast coke should possess large lump size, low reactivity, low porosity, sufficient impact resistance, as well as low ash and sulfur content. 2. Distribution of coke in China: Looking at the distribution of coke production in China, it can be seen that coking enterprises are unevenly distributed across the country, with the majority located in North China, East China, and Northeast China. 3. Uses of coke: Coke is primarily used in blast furnaces for iron production, as well as in bloomery processes for the smelting of non-ferrous metals such as copper, lead, zinc, titanium, antimony, and mercury. It serves as a reducing agent, a heat source, and as a structural component for the charge pile. The use of coke instead of charcoal in ironmaking blast furnaces laid the foundation for the enlargement of modern blast furnaces, marking a significant milestone in the history of metallurgy. To achieve favorable technical and economic parameters in blast furnace operation, coking coal used for smelting (metallurgical coke) must possess appropriate chemical and physical properties, including its properties under hot conditions during the smelting process. In addition to being widely used in iron smelting and the processing of non-ferrous metals (as metallurgical coke), coke is also used in foundry industry, the chemical industry, calcium carbide production, and ferroalloys, with varying quality requirements for each application ； For casting coke, it is generally required to have large particle size, low porosity, high fixed carbon content, and low sulfur content ； Coke used for chemical gasification does not require high strength, but it needs to have good reactivity and a high ash melting point ； The coke used in calcium carbide production is required to have as high a fixed carbon content as possible. 4. Physical properties of coke: The physical properties of coke include the sieve analysis composition of coke, the bulk density of coke, the true relative density of coke, the apparent relative density of coke, the porosity of coke, the specific heat capacity of coke, the thermal conductivity of coke, the thermal stress of coke, the ignition temperature of coke, the coefficient of thermal expansion of coke, the shrinkage rate of coke, the electrical resistivity of coke, and the air permeability of coke, among others. The physical properties of coke are closely related to its mechanical strength and thermal strength at room temperature, as well as its chemical properties. The main physical properties of coke are as follows: the true density is 1.8–1.95 g/cm3 ； Viscosity density is 0.88–1.08 g/cm3 ； The porosity is 35% to 55% ； The bulk density is 400–500 kg/m3 ； The average specific heat capacity is 0.808 kJ/(kg·K) at 100°C, and 1.465 kJ/(kg·K) at 1000°C ； Thermal conductivity is 2.64 kJ/(m·h·K) at room temperature, and 6.91 kg/(m·h·K) at 900°C ； Ignition temperature (in air): 450–650℃ ； The low calorific value of the dry, ash-free base is 30–32 kJ/g ； The specific surface area is 0.6–0.8 m2/g. This post was last edited by ryn on 2009-4-20 13:14]