Application of machine for grading animal feed in the cleaning section of feed raw materials in animal feed mill factories
The cleaning of animal feed making raw material is mainly based on the difference in the geometric size of the raw materials and impurities using the screen surface for screening. The types and particle sizes of impurities contained in different feed materials are different, so appropriate screening equipment, screen surface specifications and screening technologies should be used in the cleaning section.
1. Cleaning of pellets
The animal feed mill plants are used to refer to the materials that need to be crushed as pellets, including grain and meal raw materials.
Cereal raw materials come directly from the field, and the impurities contained in them are more complex. There are two main categories: one is impurities with a larger particle size than the cereal raw materials, such as stones, corn cobs, hemp flakes, straw, hemp rope, plastic flakes, etc.; The other is soil and fine sand with smaller particle size. At present, the most common grain cleaning equipment in animal feed manufacturing plants is the cylindrical primary cleaning screener, which is characterized by large output, low power consumption, and high removal rate of large impurities, up to 99%, but it cannot remove fine sand and soil smaller than grains.
Although the proportion of mud and sand in grain raw materials is only 0.1% to 0.4%, in a vertical silo with a capacity of more than 1,000 tons, several tons of silt will be deposited on the bottom of the silo and will be concentrated into the animal feed production process, which will make the product The quality is seriously affected, and it will aggravate the wear of various equipment, especially the die of the pelletizer. Therefore, large-scale feed mills cannot ignore the cleaning of silt in grain raw materials. It is recommended to use vibrating grading screeners in grain processing to clean grain raw materials, such as the TQLZ series cleaning screeners, which use double-layer screens with different screen holes, which can clean up large impurities and mud and sand. In addition, due to the use of metal wire woven screen, the noise of this cleaning screener is much lower than that of the cylindrical primary cleaning screen using a punching screen. The recommended sieve holes are selected according to the upper sieve 20×20 mm or φ20～φ25 mm, the lower sieve 1.5×1.5 mm or φ1.2-φ1.5 mm.
Common meal raw materials include soybean meal, cottonseed meal, rapeseed meal, peanut meal, etc. Compared with grain raw materials, it is characterized by smaller particle size, poor fluidity, more agglomerated materials, and low impurity content. To break up the agglomerated materials, the cone primary cleaning screener is usually used. According to our experience, the mesh size can be selected as φ10-φ15 mm.
2. Cleaning up powder materials
The raw material that does not need to be crushed is generally called powder. There are many types of powders in animal feed plants, and the amount of powder used is different. Most of them are by-products of the grain industry or other industries. Therefore, the impurity content is not high. The main impurities such as hemp rope and sack flakes mixed in the processing process. In the production of complete feed and concentrated feed, it can be cleaned by cone primary cleaning screener, flat rotary screen or vibrating screen.
The mixed materials should also be sieved with a cone primary cleaning sieve before granulation. On the one hand, it can clean up the impurities that may be mixed in during the processing and the impurities that cannot be removed in the raw material cleaning. Break up, which is especially important for feed after spraying. The output of the cleaning screen should be matched with the animal feed mixing equipment.
The size of the sieve used for the cleaning of powdery raw materials varies with the properties of various raw materials, generally φ6-φ10 mm, relatively good fluidity such as mineral raw materials can choose a small value, and poor fluidity such as bran The skin, fish meal, meat and bone meal, etc. should be selected with large values.
In the premix feed manufacturing process, the particle size of powder (such as phosphate) is very small, and its impurities are often fine particles produced during the processing of raw materials. Generally, it is difficult to clean up by screening machinery. Square sieve is used as cleaning equipment.
3. Application of sieving technology in product classification
The application of sieving technology in product classification. Classification is to sieve materials into two or more components and process them according to different needs. The feed industry is mainly used in crushing material classification, granular material classification and material particle size determination.
(1) Classification of crushed materials
The secondary crushing process requires the use of screening technology. In the production of ordinary livestock and poultry feed, rotary screens or vibrating screens are generally used. According to the information, the sieve hole size is φ1.2 mm.
In the process of fine pulverization of premix and fish and shrimp bait production, because the pulverized particle size of the material is often required to pass through a 60-80 mesh standard sieve (0.42-0.18 mm), if mechanical sieving is used, the particle size is too small. Cohesion of the materials and difficulty in sieving the particles will result in a decrease in the screening efficiency and an increase in the amount of reflux crushing, thereby reducing the crushing output and increasing the crushing energy consumption. Airflow classification can solve this contradiction. Airflow classification is a broad sieving technology. It controls the particle size of the material returning or entering the next process by adjusting the airflow process parameters. The airflow, wind speed and air pressure vary with the material type and its particle size control range.
(2) Grading in animal pellet feed production
In animal feed mill pelletizing process, in order to increase the output of animal feed pellet milling machines and reduce pelletizing energy consumption, large-diameter die holes are often used for production and then crushed into small pellets. After the particles are broken, they need to be classified to separate the over-fine powder (the unformed powder during the granulation process or the powder produced during the crushing process) and the over-coarse particles (the particles that are not sufficiently broken), so that they can enter The particles in the finished product processing section meet the product size requirements.
The classification of pellet feed is carried out on a two-layer sieve surface, the upper sieve is refluxed and crushed, the lower sieve is refluxed for granulation, and the middle layer is the finished product. It can be seen that the mesh size of the grading screener directly affects the product size. The size of the sieve holes used for the classification of products with different particle sizes, the particle size (mm) of the grading product is 2.40, 3.20, 4.00, 4.75, 6.35, 9.50, 12.7 and crushed particles, and the corresponding sieve size (mm) is 1.65, 2.23 , 2.92, 3.89, 5.21, 8.97, 11.5 and 1.16. It can be seen that in order to control particles of a certain particle size not to pass through the sieve, the sieve diameter should be smaller than this value.
The grading screen machine in the typical granulation process is generally fed directly by the bucket elevator. Because the vibrating screen (SFJZ series) easily causes the material to be concentrated in the middle of the screen body, the utilization rate of the screen surface is low, and the local material layer is too thick. Classification effect, therefore, it is recommended to install a buffer hopper (with a baffle inside) at the inlet of the grading screen to make the feeding uniformly along the width of the screen surface.
4.Introduction of RICHI rotary classification screener
(1)Scope of application
Widely used for material classification of many industries like grain, feed, flour, food, chemical industry, sugar, metallurgy, especially suitable for the classification of particle feed.
①Special balance mode, the inertial force in all directions is balance, small vibration, and low noise.
②Belt transmission, simple and reliable, easy and fast replacement.Imported SKF bearings to minimize the error rate.
③High-rigidity sieve vessel and heavy frame, durable and suitable for low frequency rotary motion.
④Streamline design inside, without material deposition and cross-contamination. 80-165 series use high elastic composite material as the elastic support plate, effectively reducing the noise.
⑤185-210 series use elastic supporting structure.
⑥The whole transmission system and sieve vessel can be suspended on the prefabricated suspension structure of building, and can be used for the suspension of floor type frame base.
⑦Transmission box uses belt transmission mechanism, stable and reliable operation.