Problems and improvement measures of magnetic separator Henan Hongxing


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Existing problems of magnetic separator and its improvement

Magnetic separator It is an important medium recovery equipment in heavy medium coal preparation plant. It is mainly used to recover magnetic materials in thin medium. The quality of magnetic separation has a great influence on the level of medium consumption. In many years of production practice, the magnetic separator has been unstable, low recovery rate of magnetic materials and high medium content in tailings, which leads to excessive medium consumption per ton of coal. In order to improve the work of the magnetic separator and recover the medium to a limited extent, we have done a lot of work and carried out a number of transformation, and achieved good results.

 Magnetic separator

Existing problems

1. The properties of the magnetic separator feed (i.e. the dilute medium under the product demixing screen) cannot meet the process requirements. There are two counter current wet magnetic separators in a factory, which are used in parallel. The feed concentration of magnetic separator is 24.86%, the content of magnetic material is 5.63% (30.30kg / M), the content of non-magnetic material is 319.23%, and the pulp volume is 550m3 / h (one set of 275m m3 / h). The magnetic and non-magnetic content of the feed material can not meet the process requirements, which is the main factor causing the low recovery rate of magnetic material.

2. It is difficult to adjust and control the overflow of magnetic separator tailings. In production, the tailings of magnetic separator must ensure a certain amount of overflow (about 25% of the tailings) to achieve good separation, and the overflow of magnetic separator tailings is achieved by adjusting the size of its bottom flow. The existing underflow regulating device is very inconvenient and has low precision, which can not guarantee the stability of overflow flow.

3. Uneven feeding. The feeding can not be evenly fed along the full width of the drum, resulting in the uneven flow in the separation tank. The flow velocity is too fast in the place with large flow, the liquid level is turning over and turbulent flow occurs, resulting in the increase of medium content in tailings.

4. The discharge of magnetic concentrate is not. The medium in the feed is adsorbed on the surface of the drum under the action of magnetic field, and is brought to the discharge end of the concentrate with the rotation of the drum, and falls into the concentrate tank under the action of the scraper. Due to the scraper can not scrape all the adsorbed media, a small part is still brought back into the separation tank and lost in the tailings under the impact of pulp.

5. Impurities or lump coal are easy to enter the separation tank and wear the cylinder skin. Due to the influence of the previous process, such as the breakage of the sieve plate of the de medium screen and the breakage of the screen basket of the centrifuge, there are some impurities or lump coal in the dilute medium. Once these impurities and lump coal enter the separation tank, they will wear the cylinder skin of the drum. The worn cylinder skin must be replaced in time to prevent the slurry liquid from entering the drum and causing damage to the magnetic pole inside, which increases the equipment capacity Maintenance volume and operation cost.

 Magnetic separator

Transformation implemented

In the face of the above problems, we actively respond to the above problems, and have carried out a number of modifications to the magnetic separator, as follows:

1. Adjust the parameters of magnetic separator

As the nature of the magnetic separator feed is determined by the coal preparation process and the quality of raw coal, it is difficult to change. We have to adjust some parameters of the magnetic separator to adapt to the feeding properties as much as possible. For this reason, we have done a lot of industrial tests, through comparison, the drum speed of the magnetic separator is adjusted from 1.3m/s to 1.5m/s, and the drum height is reduced from 20mm to 15mm, and good results are obtained.

2. Add a magnetic separator to increase the processing capacity

From the parameter point of view, the pulp treatment capacity of the magnetic separator can meet the needs of production, but due to the feeding properties far from meeting the process requirements, the actual corresponding flow is relatively large, so we decided to add another one on the basis of the two magnetic separators, and use three in parallel, so that the flow rate of each magnetic separator is reduced to 183 m3 / h, which is greatly reduced The load of magnetic separator plays a significant role in improving the recovery rate of magnetic materials.

3. Transform the regulating device of the bottom flow of the tailings of the magnetic separator

Before the transformation, the tailing bottom flow is adjusted by moving the cover plate on the tailings underflow pipe to change the size of the pipe orifice. During production, both the cover plate and underflow pipe orifice are immersed in the slurry, which can not be seen during operation. At the same time, there is pressure generated by the slurry, so the adjustment is not convenient and poor. So we removed the cover plate on the underflow pipe orifice, and connected a rubber hose under the pipe. We installed a clamp on the rubber hose, and changed the flow size by adjusting the tightness of the clamp. After modification, the new device is convenient and accurate in regulating the tailing bottom flow, which ensures that the tailings always have stable and appropriate overflow.

4. Transform the feeding pipe of magnetic separator

Before the transformation, the feeding material enters from one side of the feeding box, and then enters into the feeding box through each branch pipe, which easily leads to the uneven flow of each branch pipe, some of which are large and some are small. After the transformation, we feed the feed directly to the center of the feeding box, and then distribute it to each branch pipe, so that the flow of each branch pipe is relatively uniform, and the feeding can be evenly fed along the full width of the drum.

5. Install a grate in the feeding trough of the magnetic separator

A grate with a diameter of 15 * 15mm is installed at the outlet of the feeding chute, which hinders the lump coal and sundries from entering the separation tank. At the same time, the post workers are required to clean the grate and the feed chute after each shift, which not only protects the drum skin but also avoids affecting the flow uniformity of the magnetic separator.

6. Water spray is installed at the concentrate discharge end of the drum to help the concentrate discharge

We installed a row of water spray along the full width of the drum, and made the water spray direction as far as possible along the tangent direction of the arc surface of the drum to strengthen the demineralization. In this way, the concentrate not scraped by the scraper will be discharged into the concentrate tank under the action of water spray, so as to avoid concentrate loss.

economic performance

Through a series of transformation, the magnetic separation efficiency and magnetic recovery rate of the magnetic separator have been significantly improved. According to the feeding amount of 550 m 3 / h, the magnetic content of 30.30 kg / M 3, and the washing raw coal of 300 tons per hour, the recovery medium can be more than 550 m? * 30.30 kg / M? * (98.64% - 97.55%) = 181.6kg, and the medium consumption per ton of raw coal is reduced by 181.6kg/300t = 0.61kg/t. If 1.8 million tons of raw coal are washed annually and 930 yuan per ton of medium is used, the cost of medium consumption can be saved (0.61 kg / T * 1.8 million) / 1000 * 930 yuan = 102.1 yuan.

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