The process of grain processing is inextricably linked with the need for its thorough cleaning from various impurities. The presence of foreign impurities in the grain mass has a negative impact on the efficiency of its subsequent storage, since impurities can contribute to the development of microorganisms, increased humidity and self-heating. In addition, the technological characteristics of grain contaminated with impurities are significantly worsened, which inevitably leads to a decrease in the overall yield of finished products and a significant deterioration in their quality characteristics. This is why grain cleaning operations occupy a central, key place in the post-harvest processing complex. The production of a wide range of products, such as flour, cereals, ethyl alcohol, animal feed and even malt for brewing, also begins with thorough operations to clean the raw material – grain.
Grain almost always contains a certain percentage of various impurities, which are divided into weeds (weeds, minerals, organics, spoiled grains, metal impurities) and grains (other crops, damaged, shriveled). Their content is controlled by state standards and technological requirements.
Various methods used for effective grain cleaning are directly determined by the features that allow separating the main grain and the impurities:
separation by size (coarse, large and small impurities) is carried out by sifting on special sieves. For this purpose, sieve separators are used – scalpers, equipped with a sieve in the form of a short drum or a movable grate;
light impurities (dust, shells, straw, etc.) are removed by pneumatic separation using an air flow. Sieve and air separators of various designs are used to separate such impurities, and they can be combined into a single unit;
metal-magnetic impurities (nails, pieces of metal, iron ore, etc.) are separated using powerful magnets, magnetic separators;
long and short impurities are separated in indenters. If an impurity shorter than the crop itself is selected from the grain mass, such an indenter is usually called a cockle separator. If an impurity longer than the crop itself is selected from the grain mass, such an indenter is usually called a wild oat separator.
heavy impurities (stones) are removed by the vibro-pneumatic method, implemented in destoners separators, gravity separator, concentrators, combiners and sieve machines;
impurities that differ in optical characteristics (for example, color) are removed using optical sorting.
Depending on the condition of the grain mass and the purpose of cleaning, there are preliminary, primary and secondary cleaning.
Thorough cleaning brings the grain to a condition that meets the requirements of regulatory documentation. When performing secondary cleaning, the grain can be processed repeatedly also in flat-sieve sieve-air separators or drum separators. Due to the fact that the required degree of cleaning at the stage of preliminary and primary cleaning is achieved by separating easily separable impurities, then in most cases the main task of secondary cleaning is to combat difficult-to-separate impurities. Secondary cleaning may involve the use of some or all methods of separating difficult-to-separate impurities: separation by magnets, triturating, vibropneumatic and optical methods.
The OLIS company also has a ready-made modular solution (Fig. 1, Fig. 2), which has a full list of the necessary equipment.
The technological line includes a set of modern and energy-efficient equipment: a screen cleaner flat-sieve type PSO, an aspiration column KAO, a grain separator HORIZONT-K, a destoners separator OMP, a trier-oat separator TCO, as well as a gravity separator SPS
The main task of such a line is to ensure the purity of the seed material, maintain the germination parameters and select from the grain mixture the most complete and high-quality fractions that have high germination and in the future provide high yields.
Depending on specific tasks, the type of grain crop, the technological scheme of the seed line can be more or less developed and exclude some operations, and its efficiency is achieved by selecting the working parts of the machines and their adjustment.
If you are interested in OLIS equipment, you can easily place an order through our official website. Online ordering provides the following advantages:
