How to Do the Coarse Coal Slime Separation in CHPP

2020-03-18 0 Views (1148)

How to Do the Coarse Coal Slime Separation?


1. Coarse coal slime and its necessity of separation


The definition of coarse coal slime (GB/T7186-1998) :


The coal which particle size is close to coal slime, usually more than 0.3-0.5mm, and it's not easy to be separated by flotation.


Generally, the particle size of fine coal is between 0.25-2mm and it's difficult to separate by flotation method is called coarse coal slime.


Regardless of jigging or dense medium separation, the separation accuracy of materials <2mm fraction size is poor, and the separation size range of flotation process is restricted by the adhesion of bubbles and particles. And the >0.25mm coarse coal slime is easily lost in tailings due to the insufficient carrying capacity of bubbles. There is an effective separation particle size gap between gravity separation and flotation, which can easily lead to loss of low ash clean coal.


Coarse coal slime (0.25mm-2mm) accounts for about 20% of raw coal, and this part of slime contains about 60% of clean coal (ash content is 10%). If it is not properly handled, it will definitely affect the economic benefits of coal preparation plant and cause a great waste of resources.


2.Status of coarse coal slime separation and recovery


  • 2.1 Sources of coarse coal slime


Coarse coal slime sources of coal preparation plant are mainly divided into two situations. One is desliming before separation. Currently, generally the desliming screen is applied with 2mm (or 3mm) mesh, so thant there must be 0.5-2mm coarse coal slime in slurry. The other way is the non-desilting separation method. The content of +0.5mm in slurry increases due to the uneven screen mesh of sculping screen or desliming screen. The slurry is graded to ensure the floating particle size, and the coarse slime is recycled.


  • 2.2 Coarse coal slime separation equipment


Teetered Bed Separator (TBS)


Teetered Bed Separator (TBS) is developed from the old hydraulic classifier, and its classification and sorter follow the principle of interference settlement.


  • 2.3 Process flow of coarse coal slime processing


At present, the following methods are mainly adopted in the coal preparation production in China:


1.The coarse coal slime recovered by high frequency screen is not separated and directly blended into raw coal for sale;

2.Coarse coal slime returns to the main separation system and enters the cyclone or other equipment to be separated;

3.Two - product coal slime dense-media cyclone is used for separation.

4.Dilute medium from clean coal sculping screen and middlings sculping screen is preparated by magnetic separation respectively. 5.Recover coarse fine coal slime and coarse middling slime in magnetic separation tailings;

6.Spiral chute is applied to classification;

7.TBS is applied to classification;

8.Small diameter three product coal slime heavy medium cyclone is applied to classification.

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