Feeding and operation process of jig

The feeding and operation process of the jig has a great influence on the processing capacity and sorting effect of the jig.

(1) Feeding requirements

The fluctuation of the feed characteristics of the jig and the change of the feed amount have a direct impact on the process effect of the jig. Therefore, the fluctuation of the feed properties (density and particle size composition) should be as small as possible, the feed rate should be uniform, to keep the bed stable, and the bed is kept in the optimal sorting state under a certain feng shui system. Meanwhile, the feed along the width of the feed jig to be evenly distributed, with the material infeed of flushing, the coal must make the original pre-wetted. In order to ensure the uniformity of the feed properties, the coal preparation plants that may sort the coals of several mines or the coal seams with large differences in sorting properties shall adopt the measures of coal blending to achieve the purpose of homogenization of the selected coal. .

(2) Operation process of jig

1. Jigging frequency and jigging amplitude

The selection of the frequency and amplitude of the jigging is related to the feed size and bed thickness. If the particle size is large and the bed is thick, a larger flow amplitude is required and the corresponding frequency should be smaller. In order to make the rising water flow have enough force to lift the bed, there is enough space and time for the coal and meteorite replacement position. The frequency can only be adjusted by changing the number of revolutions of the damper. The amplitude can be adjusted by changing the wind pressure, the air volume, and the area of ​​the inlet and outlet of the damper.

2. Combined action of Feng Shui

The combined action of feng shui directly affects the looseness of the bed. Wind pressure and air volume play a role in enhancing rising and falling water flows. Generally, the air pressure used in the sieve side air chamber jig is 0.018 to 0.025 MPa, the air volume is 5 to 6 m3/m2·min, and the air pressure of the sieve air chamber jig is 0.025 to 0.035 MPa, and the air volume is 5-6 m3/ M2·min. The first section of the jigging chamber is larger than the second section. The air volume of each compartment is reduced from feed to overflow, but sometimes it is to strengthen the suction of the second section of the intermediate compartment and strengthen the fine coal. The permeable process, the air volume can be appropriately increased. The water for the jig includes the top water and the flush water, and the flushing water accounts for 20% to 30% of the total water. Generally, the amount of water in the first section is large, and the amount of water in the compartment at the coal supply should be larger. In order to reduce the loss of pulverized coal in the vermiculite, the amount of water in the drainage port can be appropriately adjusted. When the 50-Omm raw coal is sorted, the water consumption is about 2 to 3.5 m3/t; when the lump coal is sorted, it is about 4 to 5.5 m3/t.

3. Wind valve cycle characteristics

The pulsating flow characteristics are mainly determined by the damper cycle characteristics. For adjustable dampers, the periodic characteristics should be adjusted reasonably according to the nature of the feed, so that the pulsating flow is beneficial to the full use of the transition phase of density stratification. The choice of cycle characteristics should ensure that the bed is kept sufficiently loose during the late rise period, shortening the intake period as much as possible, and prolonging the expansion period so that it has sufficient exhaust gas. At the same time, since the bed of the first section of the jig is thick and heavy, the intake period of the first section is generally longer than that of the second section, and the expansion period of the first section is shorter than that of the second section.

4. Bed state

The state of the bed determines the effect of the stratification of the incoming material by density. The state of the bed mainly means that the bed is loose and thick.

Increasing the looseness of the bed can increase the delamination speed, but at the same time increase the influence of the particle size and shape of the feed on the stratification, which is not conducive to stratification by density. Therefore, for sorting non-grading or wide-grade coal, the looseness is smaller. Generally, it is in the range of 0.4 to 0.55; for classification, the degree of looseness is generally 0.5 to 0.55. The thicker the bed, the longer it takes to loosen and stratify. When it is too thick, the required looseness cannot be achieved under wind pressure and insufficient air volume. The thinning of the bed can enhance the sucking effect, which is beneficial to fine-grained sorting and can obtain relatively pure clean coal. However, when it is too thin, the sucking effect is too strong, the loss of fine coal permeability is increased, and the bed is unstable. When 50 to Omm coal is sorted, the thickness of the bed is generally 400 to 500 mm.

5. Emission of heavy products

The discharge rate of heavy products should be compatible with the delamination speed of the bed and the horizontal moving speed of the bed. If the heavy product is not discharged in time, it will accumulate and pollute the clean coal and affect the quality of the clean coal. If the heavy product is discharged too quickly, the vermiculite layer or the middle coal seam will be too thin, which will make the whole bed unstable, thus destroying the stratification and increasing Loss of clean coal. High-sensitivity automatic discharge devices are of great significance in the discharge of heavy products.

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