Quality requirements for coking coal

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Quality requirements for coal used in coking. Coking involves heating coal in a dry distillation furnace; as the temperature rises (reaching around 1,000°C eventually), the organic substances in the coal gradually decompose. The volatile substances escape in gaseous or vapor form, forming coal gas and coal tar, while the remaining non-volatile substances constitute coke. Coke in ironmaking furnaces serves to reduce and melt the ore, provide thermal energy, support the charge, and maintain good air permeability in the charge. Therefore, the quality requirements for coking coal are aimed at producing high-quality metallurgical coke with high mechanical strength, uniform lump size, and low ash and sulfur content. **There are specific quality standards for the coal used in metallurgical coke production, as follows:

**Bituminous coal and gas coal**
Ash content: Grades 1–13 (Grade 1 corresponds to an ash content of no more than 5.5%; each increase of 0.5% results in an upward grade, up to Grade 13).
Sulfur content: Group 1 – no more than 0.5%; Group 2 – 0.51–1%; Group 3 – 1.01–1.5%.
Moisture content: Grade 1 – no more than 0.9%; Grade 2 – 9.0–10%; Grade 3 – 10.0–12%.

**Coking coal and lean coal**
Ash content: Grade 11.5%.
Sulfur content: Group 1 – no more than 0.5%; Group 2 – 0.51–1%; Group 3 – 1.01–1.5%.
Moisture content: Grade 1 – no more than 0.9%; Grade 2 – 9.0–10%; Grade 3 – 10.0–12%