Because slurry pumps are the most extensive general-purpose mechanical equipment, they are used in various industries. Because the working conditions of these industries are not the same, the equipment failures under different application conditions are also different, but most of the failures are the same as the original equipment. The selection is directly related to the harsh working conditions after use, and the most common failures in alumina production are poor discharge and severe vibration.

1. No discharge or poor discharge during operation

The failure or poor discharge of the slurry pump is a failure encountered in almost all industries that use the slurry pump. The slurry pump does not discharge after the first commissioning or overhaul. This is related to the selection of the slurry pump or The replacement of spare parts is related, mostly because the feed liquid level of the slurry pump is too low or the steering error after the pump is running.
The main reasons for the sudden failure of the slurry pump that does not discharge under normal working conditions are as follows:
(1) Impeller or pump inlet/outlet blockage. The slurry pump suddenly fails to discharge under normal working conditions. A large part of the reason is due to the blockage of the impeller blade or the pump inlet/outlet pipe. Since the slurry delivered by the slurry pump contains a lot of solid particles, some of these solid particles have a large diameter, and the slurry generally has strong coagulability and is easy to scar, and other flexible foreign bodies mixed with it will affect the normal entry of the slurry. The pump cavity, impeller, or inlet and outlet pipelines are blocked, which also makes it difficult for the slurry to obtain the energy transmitted by the impeller. After this kind of failure occurs, there will be some abnormal noises in the pump cavity, and the current of the motor will also show an obvious downward trend.
(2) The occurrence of cavitation is related to the blockage of the impeller of the slurry pump or the inlet of the pump. The blockage of the impeller or the inlet itself will affect the discharge of the slurry pump, and the occurrence of cavitation will not only lead to The unsmooth discharge of the pump is further aggravated, and it will also produce noise and severe vibration. When the overall performance of the slurry pump is severely reduced, the discharge of the pump will be interrupted, and the motor current will be significantly jumped.
(3) Severe wear of the flow parts The main flow parts of the slurry pump have a gradual process of wear, and with the gradual wear of these flow parts, the performance of the pump will gradually decline. The poor discharge fault caused by the wear of the over-current parts has a long periodicity, and the poor discharge caused by the majority of the slurry pumps will run too smoothly, and the motor current is in a very low but very stable state.

2. Severe vibration of the slurry pump

Vibration is an inevitable phenomenon that occurs when equipment is running. It can be divided into different levels according to the severity of vibration. Equipment vibration that does not exceed the level is a normal phenomenon. If the equipment has exceeded the normal vibration level, it will directly affect the equipment. Stable operation.
There are many reasons for the severe vibration of the slurry pump. Generally, there can be the following aspects:
(1) The impeller of the eccentric load slurry pump has undergone a dynamic balance alignment treatment before leaving the factory. The quality of each part is relatively uniform, but after the long-term operation, a certain amount of wear or adhesion scars will occur, which is to a certain extent As a result, the eccentric load of the rotating parts of the slurry pump is caused. After the operation of the slurry pump, the eccentric load causes a serious unbalanced rotation force and causes the slurry pump to vibrate.
(2) Loose fixing bolts. The slurry pump relies on multiple anchor bolts to connect to the foundation. At the same time, the various components also rely on bolts to maintain the stability of the pump. Due to the existence of equipment vibration, the slurry pump will gradually cause this after long-term operation. The loosening of the fastening bolts will cause the slurry pump to lose the restraint of the fixing bolts and aggravate the vibration. At the same time, the vibration of the equipment and the further loosening of the bolts and component wear will form a vicious circle.
(3) Bearing lubrication is insufficient or the lubricant grade is not up to standard.  Good lubrication of the equipment can not only reduce the wear of the parts, but also the oil film formed by the lubricant between the two parts can absorb a large part of the vibration. While the slurry pump is rotating at high speed, the lubricating oil will form a sufficient oil film between the rolling elements of the bearing to reduce the vibration value. If the slurry pump is not lubricated or the grade of lubricant is not up to standard, the viscosity is insufficient, it is difficult to form an effective lubricant film between the bearings, or the lubricant film ruptures prematurely, it will cause severe vibration of the slurry pump and cause severe wear on the bearings.

3. Shaft seal leakage

Shaft seal leakage is the most common failure of slurry. Especially in the petrochemical industry, more than 80% of pump failures come from shaft seal leakage. Therefore, the management of shaft seal leakage will determine the utilization rate and maintenance cost of the pump. In the leakage faults of the shaft seal, more than 65% of the faults are caused by the compression spring and the cooling water fouling caused by the poor sealing of the seal end face. Therefore, the key to preventing the shaft seal leakage is to soften the cooling water of the shaft seal. , To reduce the rate of scaling of cooling water.

Maintenance of slurry pump

Due to the harsh working conditions of the slurry pump, to ensure the long-term stable operation of the slurry pump, it is necessary to maintain and maintain the slurry pump correctly to minimize the influence of the working conditions.
1) Check the lubricating oil quantity of the slurry pump bearing bracket every day during operation to ensure that the oil level is 2mm above and below the oil level line, and regularly replace the lubricating oil. The use time of the lubricating oil for the first operation of the new pump does not exceed 100h, and it can be used after the running-in period Replace according to the actual situation of the lubricating oil.
2) Regularly check and tighten the anchors and pump casing bolts. When disassembling and reinstalling the equipment, apply a thread locking agent to the bolts to avoid loosening the bolts. If the production conditions permit, the pump inlet and outlet pipelines can be regularly checked. Check and clean with the pump chamber to ensure that the pipeline is unobstructed.
3) Clean the equipment regularly to keep it clean, dry, free of oil and leakage. If the shutdown time is long, the sediment in the pump should be flushed to prevent the precipitation of the medium from affecting the next startup and operation.

The utilization efficiency of slurry pumps and other mechanical equipment has a lot to do with the reasonable selection of equipment, the correct judgment and treatment of faults, and whether the daily maintenance and maintenance of the equipment are implemented correctly. The equipment must be reasonably selected and correct. Treatment and timely maintenance require equipment practitioners to summarize and analyze the faults that are constantly exposed by the equipment, and formulate appropriate treatment plans and maintenance cycles. At the same time, it also requires the close cooperation of equipment operators and managers to ensure the plan’s success. Implementation is a prerequisite for improving equipment operation efficiency.