Grading application of coarse materials and analysis of vibrating screen equipment selection
Classification of coarse material grade: Classification of coarse material grade: The classification of materials with a sieve hole of 25 ram or more can be called coarse-grain grade classification. The equipments available for selection are: circular vibrating screen and equal-thickness sieve.
For a long time, people have a concept: the classification of raw coal 50ram should be the preferred circular vibrating screen. This is wrong or outdated. The correct and proven concept should be: the same thick screen for coal preparation plants in large and medium-sized mines. The circular vibrating screen has a simple structure, but its screening process is unscientific and is not suitable for large-scale.
The following is a description of the process of material grading and the advantages of equal thickness screens.
Vibratory screening process: Raw coal from the wellhead enters the vibrating screen, and a very thick layer is generally formed at the feed end. Fine-grained materials must be separated from coarse-grained materials by two processes: one process is a layer or a layer, and the vibration causes the fine material to sink in the lower part to contact the screen surface, and the coarse material floats on it. This process is necessary, otherwise it cannot The grading is carried out; the other process is permeable, and the fine-grained material is separated by a via.
In the screening process of the circular vibrating screen, the distribution of the screen material is thick at the feeding end, and the discharge end is very thin. The thick layer at the feeding end is very unfavorable for the sedimentation of the fine particles, and therefore, its screening efficiency Very low, it is also easy to block the hole.
It consists of multiple segments with different angles, * segment 3O. ~ 35, the second paragraph 18. ~20. . (In this case, two sections are taken as an example) the material is fed into the * segment. Due to the large dip angle, the material immediately obtains a large speed (about 1,5~n/s), the material layer is rapidly thinned, and the large particles jump due to large kinetic energy ( Even flying up, stratification is achieved on a short screen surface (see Figure 2). Therefore, the equal-thickness screen has a high screening efficiency. The second stage is for screening and the stratified material is continuously sieved. Generally speaking, the equal-thickness screen has a screening efficiency of more than 90. Due to the high-speed scouring of the material, it is impossible to block the hole under the screen. The processing capacity of the thick sieve is 6 times larger than that of the circular vibrating screen of the same specification. According to our in Shanxi The result of an industrial test of a thick sieve such as ZDS1755 in a coal mine, the production capacity of the sieve can reach 600t/h, and the screening efficiency is above 85.
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