Why Cleaning system so important for wheat flour milling machine
1. The purpose of wheat cleaning, due to the current technical constraints, wheat growth, harvest, storage, transportation and other processes will have impurities mixed. In the growing season, the wheat which is germinated and moldy because of too much rain and the wheat which is attacked by insects and diseases is the impurity in wheat, and the mixing of these wheat will affect the quality and odor of wheat flour.Therefore, in the milling wheat must be cleaned before, all kinds of impurities in wheat completely clean, so as to ensure the quality of flour, to meet the needs of the food industry and people's lives, to ensure people's health, and achieve the purpose of safe production.
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| diagram of wheat |
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| wheat and fine flour |
2. Classification of impurities impurities in the wheat can be classified according to the chemical composition and physical properties.
3.Common methods of wheat cleaning
(1)wind selection method
The method of cleaning the air dynamics properties of wheat and impurities is called wind selection method.The aerodynamic properties are generally expressed as suspended velocities.wind selection method needs participation of air media.Commonly used air - selection equipment including vertical air duct and suction separator.
(2)Screening method
The method of cleaning with different size of wheat and impurity is called screening method.Grain size is generally based on the thickness and width of wheat and impurities.The screening method needs to be equipped with a suitable screen for the movement of the sieve, and the relative motion of the sieve and the wheat is used to stratify the wheat.Small size and heavy flour would be pass through the sieve. The commonly used screening equipment has vibrating screen, rotary flat sieve and pre-cleaning screen.
(3) Using different grivatity of wheat and impurity to separate them.It is called gravity separation method. The gravity separation method needs the participation of the medium, and the medium can be air and water. The use of air as a medium is called dry gravity separation; the use of water as a medium is called wet gravity separation. The proportion of dry separation equipment commonly used gravity destoner, gravity separation, gravity separation equipment commonly used in wet stone wheat washing machine etc..
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| gravity destoner for wheat cleaning |
(4) selection method using impurities and wheat geometry and different length of cleaning method called selection method. It is necessary to use the inclined plane and the spiral surface to separate the wheat and the spherical impurity by the different geometric shapes. The common buckwheat seed throwing vehicles and other equipment. The use of different lengths for cleaning requires a rotating surface with a pocket. The short grain embedded bag holes are taken away, and the long grains remain outside the bag holes and are not taken away, so as to achieve the purpose of separation. Commonly used equipment has drum selection machine, disc selection machine, disc roller selection machine, etc..
(5) impact method by the impurity and wheat of different intensity cleaning method called impact method. Germination, moldy, diseases and insect pests of wheat, wheat and soil surface adhesion of dust, the adhesion strength is lower than that of wheat, the impact of the high-speed rotating component, broken off, the use of suitable mesh separating it, so as to achieve the purpose of cleaning. The impact of equipment commonly used are beating machine, impact machine, wheat brush machine etc..
(6) magnetic separation method using wheat and impurity ferromagnetic different cleaning method called magnetic separation method. Wheat is a non-magnetic material, in the magnetic field is not magnetized, thus cannot be absorbed by the magnets; and some metal impurities (such as iron nails, nuts, etc.) is a magnetic material in a magnetic field will be magnetized by the magnet adsorption, which is separated from wheat. Permanent magnetic drum, magnetic steel and permanent magnetic box are commonly used in magnetic separation.
（7）Grinding method;
To clean up wheat surface dust or grind wheat straw by the use of rotating rough surfaces (such as sand grain) is known as the grinding method. It is widely used for peeling and milling. Through the grinding of the surface of a few sand rolls can partially separate the wheat flour, which can shorten the powder path and make it easier to pulverize. The commonly used equipment is like peeling machine etc.
In addition to the above methods, there are other methods,such as the one according to the color of the photoelectric sorting method, the equipment is color selection machine. The current application is not yet widespread as the equipment is very expensive.
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