One of our customers coal preparation plant is mine type steam coal preparation plant, the current processing capacity is 3 million t/a, the use of "jigging + flotation" combined washing process, coal sludge water pressure filter recovery, washing water closed cycle, the main products are washing raw coal, washing clean coal, washing block, washing small block and washing grain coal. Vibrating screen is the core equipment for washing raw coal. Before the transformation, the raw coal screening system used the BMVS2100 type banana screen. With the increase of coal extraction in the mine, some problems of the equipment have become increasingly prominent, and it can no longer meet the daily production needs of the coal preparation plant, and it is urgent to optimize and transform.
Before the transformation, the BMVS2100 type banana screen used in the raw coal screening system mainly has the following problems.
1) The banana screen is a large vibration equipment, which has been put into use since the factory was built in 1999. It often has mechanical failures. Its main parts have been severely worn and cracks have appeared on both sides of the screen frame. Equipment maintenance costs up to 16,780 yuan/month.
2) Banana screen has low driving performance and needs to be equipped with an 8×15kW motor with a total installed power of 120kW. Equipment start-up operation, large current, high power consumption, average power consumption of 146.5kW·h, is not conducive to the cost control of coal preparation plant.
3) When the original design was installed, the motor end on the north side of banana screen was only 420mm from the wall), which was inconvenient for maintenance and operation. When the water content of raw coal is low, the screening time will produce large dust, and the workers need to clean a lot of floating ash, which is not conducive to occupational health. 2. BMVS2100 banana screen application transformation, the introduction of BMVS2194 high-efficiency energy-saving vibrating screen, and in the first half of 2013 completed the installation and commissioning, effectively improve the stable operation of the equipment.
2.1. Main technical indicators banana screen is a new type of equipment for equal thickness screening. Its screen surface has different inclination angles of segmentation fold shape. The main technical indicators are listed in Table 1. The raw coal material flows rapidly from the feed end of the screen surface and decreases through the high layer score stage, which is conducive to accelerating the screening of small particle materials and maximizing the screening capacity of the screen surface. Because the ratio of the amount of material and the flow rate on the screen surface of each line section is stable, the layer height of the material is balanced or gradually increasing, so it is also called the equal thickness screen.
2.2. Structural characteristics
1). Large throughput, high screening efficiency ABS2194 banana screen adopts 3 segments of 10° decreasing curved screen surface, decreasing step by step from the feed end to the discharge end, and the screen Angle is 32°, 22° and 12° respectively. Under the action of exciting force, the material on the screen surface from the inlet end to the discharge end for continuous ejection forward, forming the material flow, the larger the Angle of the screen surface, the faster the material flow speed. Due to the feeding end of the feed, the screen surface inclination is large, the material movement is fast, the material layer can be quickly thinned and stratified. Part of the unscreened material is treated in the middle section of the screen and the discharge end, and the material is gradually reduced, and the inclination and flow rate are relatively weakened. The vibrating screen adopts the principle of equal thickness screening and multi-angle curved screen surface. Compared with the traditional vibrating screen, the vibrating screen has the characteristics of large processing capacity and high screening efficiency.
2). The box exciter is installed on the girder on the upper part of the screen box, the drive shaft and the driven shaft are installed in the box, and each shaft has a pair of eccentric blocks with the same mass. Through the gear transmission, the two shafts are driven to do synchronous reverse rotation, resulting in the eccentric block rotation, resulting in a larger centrifugal force, thus forming the exciting force of the vibrating screen. A pair of eccentric blocks are arranged on the outside of the exciter box to make the box structure compact. The gear pair is installed in the box, reliable lubrication, smooth transmission.
3) The screen plate is simple in structure, easy to install the screen plate fine workmanship, 2 there is no connection bolt between the screen plates, relying on the good plastic polyurethane material between the screen plates, the screen plate is not easy to loose, reducing the occurrence of accidents. The protective cover strip is designed between the sieve plate rail seat and the support beam to prevent the coal flow from corroding the bolts. The vibrating screen plate is made of polyurethane material, which has good plasticity and wear resistance, low noise, and is not easy to produce dust when vibrating.
4) Banana screen drive system design is simple The drive system only uses a 37kW motor, through the V-belt to transfer power to the universal connection shaft, the universal connection shaft through the soft connection and then transferred to the exciter. At the same time, the motor can be set up a separate support base, thus eliminating the axis Angle change caused by the vibration of the screen body.
3. Application effect evaluation
1) Reduce dust concentration and improve the working environment In recent years, the national coal regulatory authorities have paid more and more attention to the occupational health environment of the coal mine industry, and the management has become more and more strict. In the early stage of equipment selection, technicians have fully taken this into account: At the same time, the dust management work also meets the overall requirements of "building a clean and sustainable coal preparation plant" advocated by the national environmental protection department.