The influence of fineness on coking and the selection of coal preparation crushers

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This post was last edited by kingberg on 2010-7-13 at 12:35. 1. The impact of coal blending fineness on coke quality: Blended coal is composed of various types of coal with different grades and particle sizes. Before coking, it must be crushed to achieve a more uniform composition in terms of coal quality and particle size, in order to ensure the quality of the coke. The fineness of coal grinding (the percentage of particles smaller than 3 mm in the coal mixture) has a significant impact on the quality of coke. The fineness of the coal mixture is one of the indicators for assessing coal blending quality, and it should be determined by taking into account factors such as the quality of the coal and the coking process. In production, when determining the fineness of the coal material, considerations should be given to both the quality uniformity of the coal and the production processes. In terms of the uniformity of the coal material, the finer it is ground, the better. However, if the coal fineness is low, the presence of larger particles of weakly bonded coal and ash leads to an increase in cracks in the coke and a deterioration in its uniformity. If the particle size of the coal material is uneven, segregation can occur easily during transportation; coal particles of different sizes will gradually separate into layers, with the larger and denser particles tending to gather together. Due to the different hardnesses of the various coals used in coal blending, larger particles tend to be those with higher hardness; as a result of this segregation phenomenon, different types of coal gradually separate from each other, reducing the uniformity of the coal mixture. During coking, the cohesiveness inevitably becomes poor, resulting in a decrease in coke quality. Therefore, in terms of the uniformity of the coal material, it is better to have a finer particle size. From a production perspective, the finer the coal particles, the lower its bulk density, and thus the lower the production capacity of the coke oven. When the coal is fed into the coke oven, the fine coal powder tends to be carried away by the gas, and it can also clog the rising pipes and collection pipes, disrupting the normal operation of the coke oven. Additionally, this leads to an increase in tar in the collection pipes, affecting the processes involved in its recovery. Therefore, from the perspective of production operations, the fineness of the coal material should not be too high. In top-loading coke ovens for bulk coal, the fineness of the coal material is generally controlled such that the proportion of particles smaller than 3 mm ranges from 73% to 83%. During ramming coking, it is generally around 90%. Within this range, the fineness of the coal material can meet the requirements for coke quality and coke oven operation. Excessive fine grinding of coal reduces the cohesion and bulk density of the coal used in furnaces, thereby lowering the quality of the coke. 2. Selection of crushers for coking plants: (1) For top-charged coke, hammer crushers, reversible crushers, and CHB fine coal crushers can all meet the required fineness standards; users can choose based on their own needs. (2) For compacted coke, only the CHB fine coal crusher can meet the fineness requirements; the other two types can achieve a maximum fineness of 85%.