Coking coal (or coal K) is a hard coal used to produce coke of specific strength and size under coking conditions. It is highly sought after in various industries, particularly as the main fuel for steel production and in the energy sector. Coking coals uniquely transform into a plastic state and sinter at high temperatures without oxygen.
Concentrated and unenriched coking coal has low ash content (less than 10%), minimal volatile components (15-37%), and sulfur content (less than 3.5%). Compared to other coals, coking coals have higher combustion temperatures and lower impurities. The composition of different coal deposits can vary slightly, which is crucial to consider during the carbonization process.
Coking coals, used as process fuel in various industries, are essential for industrial applications. A defining feature is vitrain, an ash component formed from the decomposition of plants without oxygen. Vitrain can melt and sinter at high temperatures, binding coal microparticles into a dense mass. Higher vitrain concentrations lead to better carbonization quality.
The primary use of coking coal is as industrial fuel, generating significant thermal energy during combustion, with an ignition temperature of 470°C. Its application in industrial processes enables the extraction of elements such as lead, molybdenum, zinc, germanium, sulfur, gallium, and more. Additionally, waste from the coal industry can be processed into refractory materials, abrasives, and building materials, with over 300 products possible from hard coal.