Coke is a solid fuel of artificial origin, which is used primarily at blast furnaces for the smelting of cast iron. It is also used in the chemical, foundry and non-ferrous metallurgy industries . This combustible material can be oil, pitch, electrode or coal, depending on the raw materials from which it is produced. Most of all coke is produced from coal.
Coke is a product that is obtained when the raw material is heated to temperatures close to a thousand degrees without access to air. As a result of chemical-physical processes, a product is obtained at the output, which contains more than 96 percent of 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 with this fuel. Such a composition allows the coke to release about 7,000 kilocalories per kilogram of substance.
Coke is a raw material that is used, in particular, for the production of electrodes. For this, the material is obtained by treating coal tar pitch (electrode coke) or oil distillates (petroleum coke). The latter variants differ from Carboniferous in that they contain a very low content of additional components (ash content from 0.3 to 0.8%).
The production of coke includes several main stages, among which:
- selection of grades of coal (gas, fatty, and coke coals can be used in different proportions);
- mixing and crushing to form a charge;
- screening, enrichment, compaction, dosing, drying;
- placement in the furnace, followed by equalization of the coke pusher rod;
- a 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, tar, hydrogen, benzene hydrocarbons , etc.) are removed from them;
- pushing out the finished product into the quench car;
- Cooling of coke by water in a tundish tower by abundant spillage;
- the final sorting of the product in classes from 0-10 to more than 60 millimeters.
Coke, the photo of which is presented above, is a substance of gray color, if it is produced from coal raw materials. If used in the initial stages of oil or pitch, 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 the 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 it can not be extracted without destroying the design of the furnace itself. For the same reason, coke production is dependent on coal supplies, because Furnaces are designed for non-stop work for a quarter of a century (20-25 years). Stopping the coke production leads to the formation of frozen slags in the furnace chamber, which are extremely difficult to remove from there.