Coke coking process
1. Coal washing: The raw coal is cleaned before coking, in order to reduce the ash contained in the coal and remove other residues
2. Coal blending: It is a process in which coal of different types of gas, fertilizer, coke and lean is prepared according to a certain proportion, and is naturally loaded into the coke oven from the top of the coke oven for coking. Generally, it is formulated as 25% gas coal, 15% fat coal, 10% lean coal, 50% main coking coal and 1/3 coal, and the flammable base volatile matter is around 25% after mutual coordination.
3. Tamping: After the coal to be blended is tamped into a coal cake with a volume slightly lower than that of the carbonization chamber, it is sent to the carbonization chamber furnace for coking.
4. Coking: After the coal is tamped, the coal particles touch high density, so that the collagen fiber body is filled to a large extent in the whole process of slagging, and the dissolution rate of the vapor is reduced, thereby increasing the working pressure and cohesive force. Make coke structure high density. However, with the improvement of the cohesive force, the collapse stress in the whole process of coal slagging increases. Therefore, for coal blending with good cohesion force, the individual obtained coke cracks increase, and the lumpiness and compressive strength decrease. Therefore, for the coal blending with more gas-coal, the crush resistance and wear resistance can be obtained under the standard of crushing and blending a moderate amount of lean components (coke powder or lean coal, etc.) and a small amount of coke and fat coal. All good coke.
Advantages of tamping coking
Tamping coking is a new coking process developed in recent years, which can increase the ratio of gas-coal or weakly sticky coal, and the ratio of gas-coal can be more than 65%. Between %-34% and moisture between 9%-11%, the strength of coke is better.
1. To reduce costs, the bulk density of coal briquettes is increased from 0.74t/m3 of side-loaded coal for iron making to 1.1 t/m3, the interval between coal particles is reduced, and the proportion of coal briquettes piles is increased, which is beneficial to the addition of high-volatile coal and weak coal. cohesive coal. The tamping coking process saves a lot of non-renewable high-quality coking coal and reduces product costs.
2. It can protect the environment, realize the operation of smokeless coal charging, and reduce the pollutant discharge of coal charging by 90%. The coking dust enters the ground dust removal station through the dust collecting hood of the dust removal and coke blocking vehicle. The process dust removal efficiency is high and the environmental pollution is reduced.
Quality requirements for coking coal
1. with coal ash
The ash in the blending coal remains in the coke after coking, and becomes one of the key quality standards for the production of metallurgical coke. Therefore, the ash content of the blending coal should be controlled. The coking rate of coal is generally around 75%. Because all the ash in the blending coal is transferred to the coke, the ash content of the coke should be 1.3 times higher than that of the fly ash. In production, it is stipulated that the fly ash content is less than 10%.
2. Sulfur content of coal blending
Sulfur coal generally exists in three ways: pyrite, potassium thiocyanate and sulfur organic matter. Generally, only pyrite sulfur is removed in general cleaning, and about 85%-90% of sulfur in blended coal remains in coke. carbon. Therefore, the lower the sulfur content in coal blending, the better, and the sulfur content in coking coal blending should generally be lower than 1.0%.
3. Coal blending volatile matter
In order to consider the needs of the iron and steel industry for metallurgical coke, and to manufacture chemical products as possible, the dry and ash-free volatile content of top-loader coke blending coal is generally 25%-30%. Limited by resources, the amount of gas coal used in iron-smelting and coking coal blending in my country is generally high, and some coking coal blending has a volatile content of 32%. In recent years, according to the shortage of fat coal and main coking coal in my country, the new technology of stamping and coking has been vigorously promoted. The gas-coal preparation can reach 75%, and the dry ash-free volatile content of the blended coal exceeds 34%.
4. Thickness of colloidal layer of coal blending
The colloid layer is an indicator of the amount of liquid that coal produces when it is heated. There must be a certain liquid substance in the coal blending to bind other substances that cannot be melted, so that it becomes a solid metallurgical coke. The specified thickness of the collagen fiber layer for coal blending is 15-20mm. However, after a large and medium-sized coking coal with multiple gas blends, the thickness of the blended coal collagen fibers is only 13-14mm, and a relatively good metallurgical industry coke is also produced.
The above indicators are calculated by the weighted average method according to the corresponding indicators of a single coal and the proportion of coal blending.