How to choose different coal processing processes
1. Anthracite
Anthracite is a kind of high-quality thermal coal with large volume and high calorific value. It can also be used for blast furnace injection or as a raw material for carbon plants. Different applications have different requirements on product quality, so the selected process should also be changed.
The upper limit of the selection may be 100 (80) mm. The heavy medium method, the jigging method or the heavy medium and jigging joint process may be selected, and the process is determined according to factors such as raw coal moisture, ash, selectivity and user requirements for product quality and grain size. When the raw coal moisture is greater than 7% (or higher, the final coal ash content is higher than 25%, and the raw coal does not meet the requirements of the user, it is recommended to use all the jigging; when the raw coal moisture is less than 7% and the final coal ash content is less than 25%, The dry grading can be carried out, and the lump coal larger than 13 (25) mm is selected by heavy selection or jigging, and the raw coal is not directly selected for direct supply to the user; since high-density coal is generally easier to select, the jigging is selected. The efficiency is close to the efficiency of heavy medium selection; at this time, it can be considered that the jigging coal is matched with the heavy medium coal preparation, that is, the high-density sorting (drainage) section is used for jigging, while the low-density sorting is selected by heavy medium. Anthracite is selected in addition to sputum, and intermediate products can also be produced; clean coal products should generally be classified.
2, lignite
The degree of brown coal coalification is low, mainly distributed in Northeast China, Inner Mongolia and Yunnan, and many of them are open-pit mining. Three coal preparation plants have been put into operation. Lignite has high internal moisture, low calorific value, and is easily weathered, fragmented and spontaneously ignited in the air. Since most of the meteorites are mudstone or muddy cemented siltstone , it is easy to soften and muddy after water, so the process should be as simple as possible. Generally, the +25mm or +50mm block raw coal is selected by heavy medium; if it is necessary to lower the lower limit to 13mm, it can be considered to use the jigging method to process 80 (50)-13mm. However, due to the longer sorting time of the jigging method, the scrubbing force of the material is stronger, which will increase the muddy degree of the vermiculite; when the material of the +80mm grade is broken, the large vermiculite which is softened by the damp will often give the crushing operation. It causes certain difficulties, so lignite with low bismuth content should be selected as much as possible. If the nature of the vermiculite and coal is appropriate, it is also conceivable to use a roller crusher.
3. Long flame coal
There are many long-flame coal reserves in the northeastern region, and they are mainly open-pit mining. The large amount and the amount of strontium are high. Some long flame coals have low water content and are suitable for dry screening. The final coal can not be selected. The lump coal is selected by heavy medium. If the coal is high in water, the screening is difficult, and the final coal ash is high, the mixed jigging process can be adopted. Or use lump coal heavy media, the final coal jigging process.
4, gas coal
As the thermal coal, when the final coal ash content is not too high (such as: less than 25%) and the quality is stable, it can meet the user's requirements, generally do not need to be washed, pre-classified, and sieve out the raw coal for export. In this way, the process flow can be greatly simplified, and in particular, the slime water treatment system can be simplified, which not only reduces the capital investment and processing costs of the coal preparation plant, but also contributes to environmental protection. The lower limit of separation of gas coal can generally be set to 13mm or 25mm. When the raw coal moisture is less than 7%, the graded particle size can be determined to be 13mm or 6mm, otherwise it can be increased to 25mm. The graded raw coal after sorting is treated by heavy medium selection or jigging. When the raw coal ash is high or the user requests some low-ash distribution of coke clean coal, all of them should be considered. In this case, the processing technology and product plan should be considered together. For gas coal with a lower thickness of colloidal layer, the slime may not be floated, and the hopping method may be adopted when mixing and selecting; when the large amount of coal and large lump coal is large, the joint process of lump coal heavy medium and final coal jigging may be considered.
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