Experimental study on the change and influence of coal slime water content under different dewatering processes Henan Hongxing

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The change and influence of coal slime water content under different dewatering processes were studied

In the coal industry, dryer has become an important equipment for coal preparation plant slime recovery and washing water closed-circuit circulation. With the continuous promotion of mechanized coal mining technology and the development of coal preparation, the scale of coal preparation plant is becoming larger and larger, and problems such as coal quality deterioration and coal slime increase also follow. A new type of dryer has been put forward coal slime dryer Two slime dryers were used in a coal preparation plant to treat the filtration dehydration of flotation tail coal. The water content of slime was about 30%, which affected the normal production of coal preparation plant. We choose slime dryer for flotation tail coal, and use different coal slurry dryers under the same test conditions Dehydration process The change and influence of water content of coal slime under different dewatering conditions are determined through experimental study, which provides basis for normal production of coal preparation plant.

 coal slime dryer

1. Characteristics of test materials

The flotation tail coal was obtained from a coal preparation plant in Shandong Province. The proportion of slime was 2G / cm3, the content of - 200 mesh was 82.34%, the ash content was 63.04%, and the calorific value was about 1700cal / g.

2. Analysis of test results

The key to reduce the water content of coal slime is to reduce the porosity of coal slime, and press dehydration can further reduce the porosity and water content of coal slime. The specific operation is as follows: the coal slime dryer stops feeding at the end of the drying period, abandons the dehydration stage of high pressure and small flow of the traditional dryer using the feed pump, and uses compressed gas to deform the wrapped slime, generate two-dimensional compression force, destroy the "arch bridge" formed between particles, change the geometry structure of the arch bridge and rearrange the coal slurry particle distribution state, so as to improve the stability of the coal slurry dryer By changing the porosity of coal slime and extruding the residual water between particles, the water content of slime can be effectively reduced.

Under the same conditions, when different dewatering processes are used, the change of water content of slime can be seen in the test process. Under the same conditions, the water content of coal slime under ordinary drying and high pressure drying tests is changed. The results show that the moisture content of coal slime is as high as 27.79% when drying alone; the moisture content of slime decreases to 26.32% after extrusion; the water content of coal slime is 22.15% when the coal slime is first blown and then squeezed; however, when the pressing and blowing are carried out at the same time, the water content of coal slime increases to 23.67%; it can be seen that for the drying and dewatering of the flotation tail coal, the water content of coal slime will be blown first and then the coal The moisture content of coal slime is determined when the mud is pressed. The water content of coal slime is different when the coal is first compressed and then compressed. The water content of coal slime when blowing first and then pressing is lower than that when pressing first and then blowing.

 coal slime dryer

In general, for slime with large particle size and loose slime, the process of pressing before blowing should be adopted to avoid short circuit and increase air consumption; for slime with small particle size and loose slime, priority should be given to blowing before pressing, so as to avoid the formation of natural fluid channel in slime after static pressure dehydration, which will be damaged during pressing It is good for drying. In addition, if the particle size is too large or too fine, the blowing process should not be adopted: if the particle size is too large, the slime is easy to short circuit, resulting in large air consumption; if the particle size is too small, it is easy to form a capillary with too small pore diameter, which will increase the drying resistance and increase the blowing pressure. When the capillary diameter is small enough, it will only be permeable and airtight.

The experimental results show that the moisture content of coal slime can be effectively reduced by increasing extrusion or reverse blowing, or by increasing extrusion and reverse blowing at the same time. The key is to determine when to increase the pressure and the reverse blowing, as well as the sequence of increasing the pressure and the reverse blowing, so as to meet the requirements of water content of coal slime, so as to obtain the drying.

With the rapid increase of raw coal washing rate and mechanized comprehensive mining in coal industry, the difficult problem of slurry drying has become a restricting factor affecting the development of coal preparation industry. Our experimental research and Analysis on drying and dewatering of flotation tail coal has certain guiding significance for coal preparation plant to select slime dryer to treat slime water.

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