1. Production continues to grow. At present, China's feed output has ranked second in the world. In 1997 , the output of concentrated feed and premixed feed reached 7.01 million tons and 1.25 million tons respectively , an increase of 71% and 73% respectively over 1996 . Self-contained feeds grew faster during this period.
2. The product structure is gradually adjusted and optimized. The proportion of concentrated feed and pre-mixed feed is continuously increasing. At the same time, the quality of compound feed is also increasing. The conversion rate of some products has reached or is close to the international advanced level.
3. The development of the feed industry in the central and western regions has accelerated. The scale and organizational structure of the company will develop in the direction of large-scale, group-oriented and integrated.
5. The ownership structure and market structure of feed enterprises have undergone significant changes. In the 1980s , basically, state-owned enterprises dominated the world. In the 1990s , with the deepening of the economic system reform, from singularization to diversification, private enterprises, township enterprises, and foreign-funded enterprises emerged from a single investment entity. Diversified investment entities such as the shareholding cooperation system, limited shareholdings, and limited liability system.
6. The production of feed additives has developed to a certain extent, but it still lags behind the feed processing industry as a whole. At present, more than 1,000 kinds of various types of additive production plants in the country produce more than 600,000 tons per year. They mainly produce lysine, vitamins, antibiotics, trace elements of minerals, and calcium hydrogen phosphate.
7. The feed machinery manufacturing industry has made considerable progress. The performance and quality of some products have reached or are close to the advanced level of foreign countries.
8. The research, education and quality monitoring system of the feed industry has been established.
2 , China's feed industry has problems
1. Feed industry and food. Food is the main raw material for feed, which is the primary factor determining the development of the feed industry. China's per capita possession of less than 400kg of grain  feed grain accounts for less than 20% of total grain output . The amount processed into compound feed accounts for less than 1/4 of the total feed grain. If 50% of the feed grain can be processed into a compound feed, it can increase the production of several billion kilograms of animal products on the existing basis.
 2. Feed industry and aquaculture industry. The relationship between the feed industry and the aquaculture industry is interdependent, mutually influential, and mutually reinforcing. It is necessary to organically combine the two, coordinate with each other, and develop simultaneously.
 3. Feed processing industry and raw material industry. The feed ingredient industry refers to all industries that use industrial methods to produce feed ingredients. The raw material industry is the product of the development of the feed industry to a certain stage. In the early stages of development, it generally lags behind the processing industry. With the development of the processing industry, the demand for various raw materials is increasing, which requires a rapid development of the raw material industry.
 4 , the status of feed product quality. In general, the quality of China's feed products is still relatively low. Compared with developed countries, the feed conversion rate is 20  30% lower .  Enterprises can only sacrifice product quality to survive.  Product quality decline directly harms the breeding industry.  Form a vicious circle of low price - low quality - low efficiency.
 5. Problems with process equipment. The domestic equipment is reliable in quality, poor in stability, short in service life and large in power consumption. The serialization, generalization and standardization of medium and small-sized feed processing equipment are low. Large-scale or complete sets of equipment with a production capacity of more than 20 tons are still in the development stage and still depend on imports. Although grease addition and spraying equipment have formed a series of defects, the quality is generally unstable. The mechanical quality is not enough. The productivity of the expansion equipment is generally too low and the power consumption is high. The lack of equipment for the development and utilization of feed resources has not resulted in mass production. Dispersion refers to the certain fluidity exhibited by the powder and granules in the case of movement. The dispersibility is related to the size, shape, surface state, impurities and moisture content of the particles, which is caused by the friction and adhesion between the particles of the material. The angle of repose of the angle of repose is that when the powder or granule is not subjected to any restriction or external force, it naturally falls to a horizontal surface to form an angle between the surface of the cone and the horizontal plane. The larger the angle of repose, the more likely it is to become arched and clogged. Automatic grading 粉 When the granules vibrate or move, due to the specific gravity and particle size of the granules, they will be scattered to a certain part, causing the redistribution of the composition of the granules. This phenomenon is called automatic grading. Generally, large and light particles are small and heavy in the lower part of the pile at the upper or edge of the pile. When the moving distance is large and the scattering speed is too fast, the automatic classification is severe. It is desirable to produce automatic grading for the cleaning of raw materials and for automatic grading of mixed powdered feeds to ensure quality. Feed bulk density refers to the weight per unit volume of the feed granules in the natural accumulation state. Usually expressed in kilograms within 1 m3 . Generally speaking, the weight is greater and the quality is better. The principle of magnetic separation cleaning. Magnetic separation is the use of the difference in magnetic susceptibility between feed materials and magnetic metal impurities to remove magnetic metal impurities. The magnetic properties of bismuth magnetic metals are highly susceptible to magnetization. Feed materials and foods are non-magnetic materials. The magnetic metal impurities mixed in the feed are magnetized, and the magnetic poles of the magnetic field attract each other and are separated from the material such as feed. The requirement for magnetic separation equipment is that the magnetic metal removal rate in the feed needs to be greater than 95% . The main working element of the magnetic separation device is the magnet. The magnet has a permanent magnet and an electromagnet. The electromagnet can generate a strong magnetic force and can be used to separate weak impurities. However, it requires an excitation power supply, which is complicated and expensive.
Magnetic separation equipment  1 Simple magnetic separation device According to the shape of the passage through which the material passes, various types of simple magnetic separators such as 蓖-type magnetic separator and slide magnetic separator are installed.
A , 蓖-type magnetic separator  is a magnetic grid composed of permanent magnetic rings. It is named after the shape of the grid. When the material flows through the magnet grid, the magnetic metal debris in the sputum stream is sucked, and it is periodically removed manually. Because of the limited magnetic field of the magnetic rod composed of magnetic rings, the magnetic force of the two magnetic rods is weak. The magnetic metal impurities are easy to pass through, so that the magnetic removal rate is not high. At the same time, the magnet is often in a friction state. The demagnetization is fast and the life is short. Iron debris also has a deterrent effect on material flow. However, the magnetic separator has a simple structure and is convenient to use, and is often installed at a feed port of a pulverizer, a granulator, etc. as a supplement to other magnetic separation equipment.
 B. Pipe magnetic separator, which installs a magnet or a simple magnetic separator on a connecting pipe. When the material passes through the pipe, the iron impurities are attracted by the magnet. In order to facilitate the manual cleaning of the iron impurities, it is easy to install. Window and prevent air leakage. The minimum inclination angle of the slide tube is 25 degrees  30 degrees for the grain, 55  60 degrees for the powder material, 10  12mm for the grain thickness, and 5  7mm for the powder . The speed of the material is 0.10  0.12 m/s .  2 The permanent magnet cylinder magnetic separator consists of two parts: the inner cylinder and the outer cylinder. The inner cylinder is the magnetic part. The outer part of the magnet has a smooth and wear-resistant stainless steel outer cover and is fixed on the outer cylinder door with a steel strip. When iron is used, the outer cylinder door can be opened to make the magnet go outside the cylinder. When the permanent magnet cylinder is in operation, the material falls from the feeding port to the surface of the cone at the top of the inner cylinder, and then scatters around the surface of the magnet cover. After the iron ratio is large, the cone surface is blocked. The inner wall is sucked by the magnet under the action of the wall reaction force and gravity, falling along the direction of the magnetic field line. Non-magnetic materials are discharged from the discharge port, and the separation of the finished material from the iron impurities is performed.   The effect is good. According to the measurement, the iron removal efficiency is as high as 99.5% or more.
 3  permanent magnetic drum magnetic separator consists of feed inlet, supply pressure gate, permanent magnet roller, discharge port, iron stowage port, drive unit and casing. The permanent magnet roller is composed of an outer cylinder made of a stainless steel plate and a semicircular core. When working, adjust the pressure door. When the material flows through the drum, the angle of the material is 35 degrees. When the iron is flowing through the drum, the iron core is sucked by the outer surface of the drum and is brought to the non-magnetic area with the rotation of the outer cylinder. The miscellaneous automatic drop is discharged by the discharge port. The material of the machine is not in direct contact with the magnet. It has a long service life and does not need to be cleaned manually. The magnetic separation effect is good, but the price is relatively expensive.  4 Preliminary clear magnetic separator In order to simplify the process, Hunan Hengyang Grain Machinery Factory improved the cylinder primary cleaning screen and permanent magnet roller combination into a primary magnetic separator. It not only has the functions of the original single machine, but also improved combination. After sharing a motor and reducer, the power consumption of the machine is reduced, and the structure is compact.
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