Mineral sizers is a new type of crusher that appeared in the 1970s, which can be used to selectively break the feed by selecting different tooth shapes and arrangements. The machine has been rapidly popularized in the coal washing industry because of its characteristics of less crushing and high block forming rate. However, different types and details of the design, especially under complex conditions often appear completely different use effects. Based on the comparison of two types of mineral sizers in the same working conditions, this paper discusses how to choose mineral sizers. The designed processing capacity of yangquan no. 1 coal preparation plant after technical transformation has reached 7 million t/a, mainly washing the raw coal of no. 3 and no. 15 coal seams mined in the mine. The washing process is as follows: The bulk raw coal of two coal seams is sorted by heavy medium inclined wheel separator, and the final raw coal of no. 3 coal seam is sorted by jig. Raw coal preparation workshop adopts jaw crusher to pretreat large lump coal. Because the raw coal is fragile, the yield of lump coal is low. In order to realize the continuity of the whole process, one use one standby double-tooth roller crusher is used to break large lump coal. The factory has purchased two kinds of mineral sizers, no. 108 and no. 107, produced by different manufacturers. After nearly two years of application practice, it is found that the selection of the two equipment is basically the same, but the use effect is different.
1. The two double-toothed roller crusher in the raw coal workshop have been used for nearly 2a time, and the no. 108 crusher has many failures, many times the reducer base screw loosening, coupling screw cutting, reducer temperature rise, current change amplitude (80~300a) and other problems, and the reducer has been seriously damaged four times, two of which are the reducer two axes pushing, crushing tooth roller breaking teeth. The gear riser is not installed in place, and the improved hollow crushing gear ring is still cracked seriously, and it is rarely used now. At present, raw coal crushing in the raw material workshop is mainly no. 107, and the whole equipment has small maintenance, low failure rate and obvious crushing effect. The products on the belt conveyor in the upper and lower flow 105 and 201 "Of the no. 107 crusher were sampled on site, and the cumulative crushing efficiency curve of the no. 107 sample was analyzed. It can be seen that the broken block rate changes obviously before and after the material is broken.
2.Mineral sizers with the further study of the theory of fractional crushing and different field conditions, the fractional crushing styles of double-toothed rollers vary, mainly reflected in the driving form, tooth structure and parameters of the tooth rolls. Drive form: There are single drive and double drive. A single drive is a single motor that drives a tooth roll and drives the rotation of another tooth roll through the gear; double drive for double motor respectively drive two teeth roller rotation mesh material crushing, and the choice of the same drive motor power is also different. Tooth structure: There are many types of graded broken teeth, generally have tooth plate, tooth cap type, tooth ring type, gear type, replaceable teeth and other types. Gear roll parameters: There are many parameters of the gear roll, mainly the diameter of the gear roll, the length of the gear roll, the center distance of the gear roll, the speed of the gear roll, etc.
The deep mining of coal has made great changes in the coal washing environment. Raw coal waste, rock hardness, bulk particle size content, etc., are increasing, which gradually tests the performance of the crusher. Therefore, it is difficult to solve practical problems in mineral sizers design according to traditional ideas. At the same time, while introducing foreign equipment and technology, it can not be hand-me-down, and it is necessary to combine china's actual conditions, on-site coal quality, mining technology and processing technology to carry out customized optimization design, and mechanically imitate several foreign equipment models to set on-site conditions, which will inevitably cause problems. In view of the crushing condition of large lump coal with high quantity of dirt in site, the following aspects should be considered in the design of crusher.
3.1 For large materials, large roll diameter selection design concept is adopted. According to the principle of graded crushing, increasing the diameter and center distance of tooth rolls within a reasonable range can increase the meshing angle, enhance the meshing ability, and increase the probability of one-time crushing materials and the material passing ability. At the same time, due to the reduced contact probability between materials and crushing teeth, the over-crushing is reduced and the block forming rate is increased. The disguised phase increases the life of the tooth roll. 3.2 reasonable selection of tooth type and layout for different materials first, due to the large impact of the crushing of hard materials, the reliability of the crushing teeth is mainly considered. The traditional tooth type of tooth cap and tooth plate type are difficult to adapt to this condition, and the crushing ring structure is the first choice. Second, with the emergence of large mines, large processing capacity is a new requirement for the crusher. According to the theory of graded crushing, the length of the tooth roll is the key factor to ensure the processing capacity. Due to the limitation of the feeding mode, reasonable selection of the crushing gear arrangement can achieve the designed processing capacity, otherwise there will inevitably be problems such as tooth roll blocking, insufficient processing capacity and local wear.
In order to ensure the smoothness of materials, the wide range of particle size adjustment function is the development trend of graded crushing, and the field requires that the wide range of particle size adjustment of the equipment can adapt to the rapidly changing market, and the wear of the equipment itself also requires wear compensation. Mineral sizers can be adjusted in a variety of ways. The most basic thing is to ensure the adaptability of the adjusted material, so targeted choices are needed.
The working conditions of coal mine are complex and changeable, so it is very important to choose the tooth roller mineral sizers of the right scheme according to the working conditions on site. The choice of details of the scheme sometimes determines whether the whole equipment can solve the actual problems on site. The practical application of yangquan no. 1 coal preparation plant proves this. According to the actual application of the field comparison, the selection parameters of the tooth roll, the tooth shape and layout, the particle size adjustment mode and other factors need to be carefully considered in the selection of design.