Equipment and requirements before the puffing section

The fineness of the raw material before puffing is not only related to the crushing equipment, but also needs to involve the screening equipment, that is, the fineness of the final raw material is guaranteed by the crushing equipment and the screening equipment.

First of all, the selection and control of crushing equipment is the key to the whole process design. The pulverization fineness of the raw materials is required to reach 80 meshes. At present, a vertical ultrafine pulverizer is generally selected, and the current hammer pulverizer cannot meet the requirements. In addition, the raw materials are required to achieve such fineness, and there is also a strict control requirement for the ultrafine pulverizer used.

Secondly, we must pay attention to the requirements and control of screening equipment. After the material is pulverized, there will be a small amount of large particles mixed in it, and there are also some impurities in the whole process. In addition, during the pulverization process, the fibers in the material are relatively small due to the relatively small bulk density, and some fibers are not well cleaned. smash. Some of these impurities and fibers are "melted" during the extrusion process of the extruder, but some of them will block the die hole before reaching the die hole. Even if some fibers pass through the die hole, some of them will hang on the cutter, thus affecting the cutting The knife cuts the puffed product, so that the appearance of the puffed particles will be reduced.

Therefore, a good screening equipment needs to be set up in the process before the puffing section. The current good practice is to configure a high square screen after the crushing equipment, and to screen the material once again when it reaches the puffing bin to prevent impurities in the process from mixing into the material.

Requirements for raw material formula 

For starchy ingredients in recipes, flour is better. The test uses different starch-containing raw materials to process small particles with a mold of 1.0 mm. When other raw materials remain unchanged, the formula of starch-containing raw materials is to add 26% corn, wheat and flour respectively. Such different formulations are produced by a single-screw extruder. On the premise of the same processing parameters, the effects of using wheat, corn and flour as starch raw materials on extruding are obtained. It was found that the floating rate of the three is that corn is not as good as wheat, and wheat is not as good as flour. The floating rate of flour can reach more than 98%, while that of corn is only about 80%. At the same time, it was found that when processing corn as the starch raw material, more fibers were glued to the blade, resulting in uneven incisions and easy to roughen the surface of the particles.

Requirements for the fineness of raw materials before puffing

The processing of small particle extruded aquatic feed has extremely strict requirements on the crushing fineness of raw materials. Theoretically speaking, when the crushing fineness of the raw material reaches 100% and passes through a 60-mesh sieve, it can be ensured that the extruder with a die hole of 1.0mm can be used for normal production. However, practice has proved that when such a pulverization fineness is produced, after the extruder runs for a period of time, the die holes begin to block, the expansion coefficient of the particles will gradually increase, and the extruded particles will become longer. When more die holes are blocked, and the speed of the cutter reaches the limit and the length of the puffed particles cannot meet the requirements, the only option is to stop the die to clean the die.

In addition, special attention should be paid to the fact that when producing small-granule extruded feed, if the formula contains cashmere, wool, leather, cotton raw materials and other special fibrous raw materials that are not easy to meet the crushing requirements, it will bring a lot of unnecessary trouble to the production. , not even normal production. Because these plush and fiber raw materials are sieved, even if they can be sieved, it is inevitable that there will still be plush and fiber aggregates that cause mold blockage or sticking of the cutter, which will affect the normal production.

Therefore, in order to be able to produce stably for a long time, it is recommended not to contain cashmere, wool, leather, cotton raw materials and other special fiber raw materials that are difficult to meet the requirements of grinding, and the grinding fineness of the raw materials should reach 100% and pass an 80-mesh sieve. Well, the minimum should reach 98% and the maximum particle size of the sieve should not exceed 0.3mm. Under such fineness, the raw material can ensure the stable production of the extruder for a long time. At the same time, the appearance of the extruded particles is smooth and beautiful due to the finer pulverization of the raw material.