Application of screening equipment in feed grading
The application of screening equipment in product grading is mainly to screen materials into more than two components and treat them according to different needs. The feed industry is mainly used in pulverized material classification, granular material classification and particle size determination of materials.
1. Grading of crushed materials. The secondary grinding process uses screening technology. In the production of ordinary livestock and poultry feed, rotary screens or vibrating screens are generally used, and the substances on the screen are refluxed and crushed, and the substances under the screen enter the batching silo.
In the micro-grinding process of premix and fish and shrimp bait production, because the particle size of the material crushing is often required to pass through the 60-80 mesh standard screen, such as the use of mechanical screening, due to the particle size is too small, the material agglomerates and bonds, and the particles are difficult to screen, which will cause the screening efficiency to decrease, the reflux crushing amount to increase, so that the crushing output decreases, and the crushing energy consumption increases. Airflow grading can resolve this contradiction. Airflow classification is a generalized screening technology, which controls the particle size of material backflow or into the next process by adjusting the airflow process parameters, and the air volume, wind speed and pressure of the airflow vary with the material variety and its particle size control range.
2. Grading in pellet feed processing. In pellet feed processing, in order to increase the output of the pellet making machine and reduce the energy consumption of granulation, large-diameter die holes are often used for production, and then broken into small particles. After the particles are crushed, they need to be graded to separate the too fine powder (unformed powder in the granulation process or the powder generated during the crushing process) and the too coarse particles (particles that cannot be sufficiently crushed) so that the particles entering the finished product treatment section meet the product particle size requirements. The grading of pellet feed is carried out by a two-layer screen surface, the upper sieve is reflux and broken, the lower sieve is reflux granulation, and the middle layer is the finished product. It can be seen that the sieve hole specifications used in the grading screen directly affect the particle size of the product. Different particle size specifications of products are graded with different screen sizes, to control a certain particle size particles do not pass through the screen hole, should use a smaller screen diameter than the particle size value.