Maintenance of Mineral Sizer at the Coal Preparation Plant
Overview
Our Indonesian client, has a large-scale coal preparation plant in Central Kalimantan. It was officially put into operation in August 2022 and mainly conducts washing and selection of raw coal mined from the Central Kalimantan coal mine.
The proportion of large pieces of raw coal and coal gangue in the raw coal produced by the Central Kalimantan coal mine is relatively high. Mineral sizer to crush it before it enters the washing and selection process.
Mineral sizer analysis
Mineral sizer is a new type of crusher, featuring a compact structure and strong adaptability. It has great prospects in the application of large raw coal and coal gangue materials. Its main features are as follows: it adopts a four-tooth structure with long teeth, small roller diameter, spiral tooth distribution and multiple crushing discs, which is particularly suitable for coarse crushing.
Under the two crushing rollers, there are crushing beams, forming a three-stage crushing process of crushing teeth and crushing beams. The crushing ratio is large, the particle size after crushing is uniform, and the particle size after crushing can be adjusted. The Mineral sizer has a compact structure and occupies a small space. The roller rotates at a low speed, thus resulting in less wear, low noise and less dust.
The basic design is simple, adopting an integral structure. The drive device is directly connected to the Mineral sizer frame, significantly reducing the force transmitted to the foundation. It has strong adaptability to materials. In terms of the hardness of crushed materials, it is greater than that of ordinary toothed roller and feeding crushers. The cross arrangement of long roller teeth plays a role in mutual combing, and it can crush sticky materials.
Analysis of Common Faults of Mineral sizer
The teeth of the tooth plate are worn
The Mineral sizer gear plate component in the coal preparation plant is a vulnerable part. The working frequency and workload of this component are both very high, so its service life is relatively short and the usage cost is relatively high. From the perspective of practical application, when the teeth of the Mineral sizer gear plate are severely worn and not replaced in time, it will lead to a series of production problems such as reduced crushing efficiency, excessive crushing particle size, material blockage in downstream equipment, and reduced washing and selection efficiency.
Especially when the coal quality deteriorates and the gangue content in the coal increases, the teeth of the tooth plate wear out more quickly, and the tooth plate basically needs to be replaced every three months.
The coupler is damaged.
In the structure of the crusher, the Mineral sizer coupler is connected to one end with the motor pin and the other end with the spline of the reducer, serving as a flexible connection during the operation of the Mineral sizer. During the operation of Mineral sizer, large pieces of gangue or other debris such as ironware often get stuck on the toothed rollers, and this malfunction is very likely to cause damage to the coupler, resulting in the wear of the coupler splines.
This is the most common failure of the coupler. During the operation of the coupler, the “0” ring is also very likely to be damaged, causing the oil chambers on both sides to be connected and resulting in an internal leakage fault. In addition, if the coupler is used for too long, the fault of cracking of the coupler housing may also occur.
Reducer failure
In the entire Mineral sizer structure, one end of the reducer is connected to the coupler, and the other end is connected to the gear roller. Both ends are in a spline connection form and mainly serve to reduce speed. In actual use, faults in reducers occur less frequently, so their service life is relatively long. Generally, under proper maintenance and care, the service life of a new reducer is over 8 years.
However, due to the poor environment of the coal preparation plant and the presence of coal dust in the air, which can easily contaminate the equipment, in terms of daily maintenance and upkeep, it is necessary to frequently clean the breathing holes of the reducers to prevent blockage and oil leakage. In terms of lubrication, the oil should be added strictly in accordance with the standards and must not exceed the specified oil level.
During the operation of reducers, the common faults mainly include: oil leakage at the input or output parts of the reducer, damage to the high-speed shaft, bearings, gears, etc., and detachment of the outer sleeve of the gear coupling, etc.
Gear roller damaged
The Mineral sizer toothed roller has a simple structure and rarely gets damaged in actual use. However, once a fault occurs, it is difficult to repair and takes a long time. The most common fault in its use is the damage of the toothed roller bearing.
As a key component supporting the rotation of the gear roller, the damage of the gear roller bearing is not caused by a single factor. Common causes include lubrication failure, installation deviation, abnormal working condition load, and seal failure, etc.
Common troubleshooting of Mineral sizer
Troubleshooting of tooth plate faults
The main task is to regularly inspect the wear of the teeth on the tooth plate. Replace the tooth plate with a new one in a timely manner based on the degree of wear to prevent a series of production problems caused by excessive wear of the teeth. Meanwhile, in response to changes in coal quality, the replacement cycle of the tooth plates can be appropriately adjusted. When the gangue content in the coal increases, the replacement cycle should be shortened to ensure the normal operation of the crushing process
Coupler fault handling
The most common fault of couplers during use is spline wear. During the inspection, if wear of the splines is found, iron powder can also be detected at the connection between the coupler and the reducer. Therefore, once iron powder is detected, the condition of the splines in the coupler should be carefully observed to determine whether it can still be used.
In the event of a coupler failure, the solution is to replace the coupler, but there are hoisting issues during the replacement process. In response to this situation, a movable hoisting frame was made by ourselves in practice to meet the replacement requirements of each coupler.
Troubleshooting of reducer faults
The reducer has malfunctioned and needs to be replaced. Due to the limited working environment within the factory, when replacing the reducer, the entire crusher must be pulled out, and then a crane should be used in conjunction for the reducer replacement.
During the installation process, it is essential to align the output shaft splines with the gear coupling first, and then tighten the ground corner bolts item by item.
Electrical fault handling
Mineral sizer contains fewer electrical components and has a relatively simple electrical circuit. The most common electrical fault is slippage without fault. The occurrence of this fault usually has only two possible causes: one is that the proximity switch is damaged or the distance is improper;
The second type is electrical circuit faults, including program faults, line faults, and improper time setting of speed relays, etc. Therefore, when dealing with faults, it is only necessary to identify the cause and handle it specifically.
