In the process of feed processing, the cleaning of raw materials is a very important part. Phenomena such as blockage of the slide pipe, poor material path, idling of the conveying machinery, damage or breakdown of the crusher screen and the pelletizer die caused by the imperfect cleaning process occur from time to time. To avoid the above phenomenon, the following points should be paid attention to in the design of the cleaning process.
1. Reasonable selection of magnetic separator
Impurities such as nails, bolts, nuts, small iron blocks, etc. mixed in the feed ingredients are very harmful to the high-speed shredders and pelletizers. In the slightest, they can cause the bottom of the screen to penetrate, and in the worst case, they can damage the die and burn the motor. There are two types of magnetic separation equipment often used in the design, one is a permanent magnet cylinder, and the other is a permanent magnet drum. The former has a small volume, a small footprint, no power consumption, and an ideal demagnetization effect. But it is only suitable for powder and light materials with smaller geometric dimensions. Moreover, the adsorbed metal foreign matter needs to be manually removed on a regular basis. Compared with the latter, the cost is higher and the volume is larger, but it is also suitable for materials such as cakes with larger geometric dimensions and bran suitable for agglomeration.
2. The position arrangement of the magnetic separator in the process
①Place the magnetic separator after the primary cleaning screen and in front of the pulverizer, which can effectively remove the metal impurities in the granular raw materials and avoid damage to the pulverizer.
②A magnetic separator is installed on the granulating powder bin, which can effectively prevent the metal impurities mixed in the auxiliary materials from entering the granulator and causing damage to the die.
③The magnetic separator is installed on the packing scale. This method is not commonly used in process design, but it is necessary to remove metal foreign matter in raw materials that have not been initially cleaned, so as to further improve and ensure the quality of finished feed.
3. Reasonable selection of various cleaning screens is the main equipment for cleaning and removing impurities in feed factories. Commonly used are cylindrical primary cleaning screens and powder cleaning screens.
The cylinder primary cleaning screen is mainly used to clean granular raw materials, such as corn cobs, hemp rope, cloth pieces, stones, soil blocks, straws, etc. The cylinder primary cleaning screen is not very suitable for powder, mainly because the powder has poor dispersibility and is easy to accumulate and block on the feeding chute, which makes the production unable to proceed smoothly. The cylindrical primary cleaning screen has the characteristics of simple structure, small volume, large output, low power, convenient installation and maintenance, etc. The screen cylinder with suitable sieve holes can be selected according to the nature of the material.
The powder cleaning sieve is mainly used for the cleaning of powdered raw materials in the feed factory, which can effectively remove the large impurities mixed in the powder, and can break up the powder that is clumped into agglomerates. The feeding of the cleaning screen is forced by a screw, so the powder can be smoothly fed into the horizontal screen cylinder, and the blockage of the powder during the conveying process can be avoided. Because the device has radial spokes, impurities such as rope ends are easy to wrap around and difficult to remove during operation. But in general, this model has the advantages of compact structure, easy installation, high impurity removal efficiency, stable operation, and convenient screen change.
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