Strength of coke

1. Improve the quality of the coking coal used and ensure proper blending (good coal yields good coke). 2. Properly pre-treat the coal material (such as moisture adjustment, pre-crushing, etc.). 3. Control the coking process properly (reasonable heating regime and longer coking time). 4. Use the dry quenching technology (CDQ).

It should also be added that increasing the bulk density of bulk coal can improve the strength of coke (for example, switching from gravity feeding to screw feeding in top-charging coke ovens can also enhance coke strength).

Just to add； Infiltrating additives.

Just to add； Infiltrating additives.

A portion of the coal used for coking is taken from the coal preparation system, mixed with a binder, and compressed into shaped coal; this shaped coal is then combined with the remaining bulk coal for use in coking. Thanks to the increased packing density of the coal material and the effect of the binder in modifying its properties, the quality of the coke can be significantly improved. Tests conducted by Anshan Thermal Energy Research Institute of China Iron and Steel Group in collaboration with Baotou Iron and Steel Group and Anshan Iron and Steel Group on industrial coke ovens using blended coals showed that when the proportion of blended coal was 30%, it was possible to incorporate 8–12% more weakly bonded coal; as a result, the M40 value increased by 2–3%, while the M10 value improved by 0.5–1.0%. This process can improve coke quality and allow the use of more weakly caking coals, thereby expanding the resources available for coke production. Baosteel’s Phase 1 and Phase 3 projects introduced coal blending technology from Japan, which has been in use to this day, with the proportion of blended coal ranging from 15% to 30%. 3.3 Coal Moisture Regulation Process The coal moisture regulation process is a technology developed by Nippon Steel in the 1980s. It aims to reduce the moisture content of coal used in firing, and to minimize fluctuations in this moisture content caused by the dewatering processes in coal washing plants as well as climatic factors. After coal moisture adjustment, the moisture content of the blended coal is controlled at around 6%. Using this process technology helps to improve the quality of coke (including cold and hot strength), increase the production capacity of coke ovens, reduce energy consumption in coke production, stabilize oven operation, minimize coke-making wastewater, and extend the lifespan of coke ovens. Its disadvantages are dust generation during coal transportation, graphite formation in the carbonization chamber, and an increase in the amount of tar residue. If a factory adopts coal moisture control technology, the moisture content of the coal can be reduced from around 11% to 6.5%, thereby increasing the production capacity of the coke ovens by 7–8%. The energy consumption for heating the gas in these ovens is reduced by 500 kJ/kg, and the amount of residual ammonia water is decreased by 30%. Meanwhile, the mechanical strength of the coke improves as well. Currently, coal humidification in Japan mostly relies on process equipment that uses steam generated from coke dry quenching for direct heating, or fluidized bed dryers that use flue gas for direct fluidized drying. Several institutions in our country are also developing this technology and related equipment, and have made significant progress. It is recommended that these institutions strengthen cooperation and increase efforts in the development of this technology, so as to enable its application in production at an early date. A crushing process is selected for the blended coal; in this process, the blended coal is first fed into a fluidized bed air classifier for grading. Fine-grained coal is carried away by the wind as a product, while the coal particles that are heavier, coarser, and have a higher ash content sink to the bottom of the bed; these particles are then removed using scrapers, crushed twice, and subsequently fed into a air classifier for further separation. This process is repeated continuously. Since this process will

One more thing to add； The incorporation of additives can increase coke strength.

It mainly involves maintaining the quality of the coal blend and the heating regime.