1 Introduction
The iron impurities mixed in the crystal in the abrasive and the ferromagnetic substance mixed in the crushing process cause a large amount of iron spots in the manufacturing of the grinding tool. It not only affects the appearance quality, reduces the grinding performance of the abrasive, but also reduces the quality of the abrasive tool and even causes waste. Therefore, magnetic separation and iron removal is indispensable for the granulation process of any abrasive, and is used for abrasive grain selection. The equipment mainly has three electromagnetic magnetic separators. In the past two decades, with the application of rare earth permanent magnets, magnetic separation technology has been amazingly developed. Rare earth permanent magnet having excellent properties can be made excellent performance rare earth permanent magnet magnetic separator, neodymium-iron-boron magnets made of rare earth permanent magnetic drum separator and the magnetic separator has several distinct advantages as compared to (1) Permanent magnets do not require the power source itself to be magnetic and do not require any cooling liquid. Therefore, the structure of the magnetic separator is simple, and the cost and maintenance cost are low. (2) The magnetic field strength is stable. This paper introduces the structure, working principle and application status of rare earth permanent magnet cartridge magnetic separator in order to improve understanding and develop a reasonable magnetic separation process for the abrasive industry.
2 Development of rare earth permanent magnet drum magnetic separator
2.1 Structure of drum type magnetic separator
The permanent magnet drum type dry magnetic separator for abrasive magnetic separation adopts multi-roller tilting arrangement, and adopts three different field strengths of weak, medium and strong in single setting, so that it has continuous magnetic separation of weak, medium and strong magnetic separators. Effect. It mainly consists of a hopper, an electromagnetic vibrating feeder device, and a magnetic system rocking device. The material enters the electromagnetic vibrating feeder from the hopper, and the feeding is achieved by adjusting the amplitude of the feeder. There are three discharge ports on the body, the former is the non-magnetic material discharge port, the latter is the magnetic material discharge port, and the middle is the mixture discharge port. The drum adopts a magnetic structure in which a fixed magnetic system and a rocking magnetic system are combined. According to the magnetic properties, particle size, specific gravity and quality requirements of the magnetic particles in the abrasive, the roller transfer, the thickness of the feed layer and the position of the adjustment plate and the roller are adjusted to achieve the best sorting effect.
2.2 Working principle of drum type magnetic separator
The magnetic separation of the material is achieved by the action of magnetic force and mechanical force on the particles in the non-uniform magnetic field of the permanent magnet roller. When the selected material passes through the magnetic field, due to the magnetic force of the magnetic particles and the non-magnetic particles, the magnetic particles are adsorbed on the surface of the cylinder by magnetic force in the sector magnetic field, and after multiple magnetic tumbling and decoupling from the magnetic field, the magnetic The outlet of the object is discharged. Non-magnetic particles are under the action of centrifugal force. It is discharged from the surface of the drum from the previous non-magnetic material outlet, and the particles discharged from the intermediate port are mixed materials.
2.3 Magnetic circuit design and magnetic calculation
The magnetic system of the cylindrical magnetic separator is a combination of neodymium iron boron magnets, an open magnetic circuit design, and the magnetic system is designed to be gradually open. Through our many years of in-depth research. We designed the magnetic system of the first one above to be the same pole along the axial direction of the drum, arranged in the circumferential direction of the drum N·S, and adopting a rocking magnetic system. The lower two turns are designed to be the same pole in the circumferential direction of the drum, and the drum is arranged in the axial direction of the N·S, using a fixed magnetic system.
The calculation of the magnetic force of the material during sorting:
Magnetic force: Fm=mXHdH/dx
Where: m is the mass of the material particles, X is the magnetic susceptibility, H is the magnetic field strength, and dH/dx is the magnetic field gradient.
It can be seen from the equation that the magnetic force can be increased only by using a reasonable magnetic field strength and magnetic field gradient.
2.4 Main technical parameters of drum type magnetic separator
The main technical performance of the Sancha permanent magnet magnetic separator is as follows:
Roller diameter 400mm
2. The effective length of the drum is 750mm
3. Production capacity 1.5~3t/h
4. Selected particle size 0.045 ~ 6mm
5. Roller rotation number is 50~260r/min
6. The highest magnetic induction intensity on the surface of the drum is the first 锟300mT, the second 锟350mT, the third 锟≥450Mt
7. Transmission power 1.5kw
8. Dimensions 1770 × 1780 × 2400 (mm)
9. Machine weight 1.5t
3 barrel magnetic separator in the abrasive industry
Kun separator with three permanent factory Henan brown corundum magnetic black silicon carbide results shown in Table 1
Table 1
Material specification | Raw material magnetic content% | Sancha electromagnetic magnetic separation result% | Three-dimensional permanent magnet magnetic separation result | standard requirement |
C60# | >1 | 0.0240 | 0.0049 | ≤0.0210 |
C60# | >1 | 0.0250 | 0.0068 | ≤0.0210 |
C60# | >1 | 0.0270 | 0.0089 | ≤0.0250 |
A150#_0 | 0.9820 | Too much tailings cannot be magnetically selected | 0.023 | qualified |
A150#_0 | twenty three | Too much tailings cannot be magnetically selected | 0.0445 | qualified |
The results of magnetic selection of brown corundum in a large enterprise in Shandong are shown in Table 2.
Table 2
Material specification | Raw material magnetic content% | Sancha electromagnetic magnetic separation result% | Three-dimensional permanent magnet magnetic separation result | standard requirement |
A46# | 0.0410 | 0.0316 | 0.0240 | 0.0280 |
A four-stage sand | 0.0426 | 0.037 | 0.0249 | qualified |
The results of magnetic selection of Baigangyu, a large enterprise in Sichuan, are shown in Table 3.
table 3
Material specification | Raw material magnetic content% | Sancha electromagnetic magnetic separation result% | Three-dimensional permanent magnet magnetic separation result | standard requirement |
WA70# | 0.89 | 0.0032 | 0.0020 | 0.0021 |
4 Conclusion
4.1 Compared with Sancha electromagnetic magnetic separator, rare earth permanent magnet three-cylinder magnetic separator has the characteristics of energy saving, safe and reliable work, convenient adjustment and low maintenance cost, especially showing its unique superiority in large production. Sex.
4.2 The barrel magnetic separator assembled with NdFeB magnets has high magnetic field strength and reasonable gradient. The first 锟 adopts the rocking magnetic system. During the sorting process, the ferromagnetic material tumbling on the surface of the drum without the magnetic aggregate abrasive and The iron impurities are thoroughly separated, and are particularly suitable for the magnetic separation of fine powders with high magnetic content.
4.3 In the abrasive production, the process of removing the magnetic substance by acid washing can be partially replaced, the process flow is reduced, and the environment is protected.
references
1 Meng Qinghui and Li Yinjiang, editor of the Abrasives Technical Manual, the first edition in October 1993.
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