Coke is a solid fuel of artificial origin, which is used mainly in blast furnaces for smelting cast iron. It is also used in the chemical and foundry industries and in non-ferrous metallurgy. This combustible material may be petroleum, pitch, electrode or coal, depending on the raw material from which it is made. Most coke is made from coal.
Coke is a product that is obtained by heating the source material to temperatures close to a thousand degrees without air. As a result of chemical-physical processes, the output is a product that contains more than 96 percent carbon. Also, coke may contain ash, sulfur, phosphorus and other substances, the amount of which, however, should not be high, because it can affect, for example, the quality of steel smelted using this fuel. Such a composition allows coke to release about 7000 kilocalories when burning one kilogram of a substance.
Coke is a raw material that is used, inter alia, in the manufacture of electrodes. To do this, the material is obtained by treating coal tar pitch (electrode coke) or oil distillation products (petroleum coke). The latter options differ from coal in that they have a very low content of additional components (ash content from 0.3 to 0.8%).
Coke production includes several main stages, including:
- selection of coal grades (gas, fatty, coke coals in different proportions can be used);
- mixing and crushing to compose the mixture;
- screening, enrichment, compaction, dosing, drying;
- placement in a furnace with subsequent alignment with a coke pusher bar;
- The direct coking process (about fourteen and a half hours), as a result of which the coals are sintered, and most of the excess substances (ammonia, resins, hydrogen, benzene class hydrocarbons , etc.) are removed from them;
- pushing the finished product into the extinguishing car;
- cooling of coke with water in the extinguishing tower by abundant spilling;
- final product sorting into classes from 0-10 to more than 60 millimeters.
Coke, the photo of which is presented above, is a gray substance, if it is made from coal raw materials. If oil or pitch is used at the initial stages, the shades of the final product of the coking process may be somewhat different.
Coke is a strategic product that must be constantly supplied to metallurgical plants. This is due to technological processes in the blast furnaces, which work without stopping. If the blast furnace stops for more than ten hours, the metal inside freezes and cannot be removed without destroying the structure of the furnace itself. For the same reason, coke production is dependent on coal supplies, as furnaces are designed for non-stop operation for a quarter century (20-25 years). Stopping coke production leads to the formation of solidified slags in the furnace chamber, which are extremely difficult to remove from there.