Primary Grain Cleaning. How Sieving Machines Help

Grain purity is one of the main indicators of quality. Harvests just collected from the fields contain various impurities that reduce product quality after processing. Therefore, the material is cleaned on specialized machines.

Impurities are removed in three types:

1. Grain (thin, sprouted, underripe, crushed, pest-damaged);
2. Weed: mineral impurities (soil, sand, slag), organic weed (straws, husks, stem and leaf particles). These also include seeds of wild plants and remains of pests;
3. Hazardous. These are dangerous to health seeds of cockle, mustard, plantain, and other poisonous plants.

Most impurities are separated using traditional methods with air flows and sieving mechanisms on primary grain cleaning machines. The rest are removed on specialized units.

Equipment: what it is and how it works

The first stage of grain cleaning begins immediately in the combine. It is called preliminary and is performed using wind cleaners. At this stage, the main mass of organic impurities is removed from the grain material with minimal content of broken and crushed grains.

Primary grain cleaning consists of several operations. First, there is winnowing, i.e., division into two fractions. Light ingredients gather in one part, heavy ones — in the other. This is done using an air stream moving at a calculated speed.

During this process, light particles with different aerodynamic properties from grain are separated. The term "wind speed" is used in calculations, which denotes the speed of the air stream. At this point, particles transition into a suspended state and float in the air.

The wind speed of fully mature grain differs from that of other particles in the total harvested mass, such as dust, straw, soil. Most crop grains float at an air stream speed of 8-12 m/sec. Light weed crops require a lower speed.

The material sent for primary cleaning must arrive with moisture not exceeding 18% and contain no foreign impurities more than 5%. After passing through cleaning machines, the material is sorted into three fractions:

1. clean;
2. feed-grade;
3. impurities.

Cleaning machines are commonly used, such as ZVS-20, ZVS-20A, OZS-50, and others. For example, ZVS-20A is designed for cleaning oilseed, cereal, and legume crops. It is included in grain cleaning complexes. Grain is cleaned using sieves and air flow. This removes small and weed impurities.

A sieve unit consists of:

• air section with a feed chamber;
• settling chamber with a fan;
• sieve section with a cleaning mechanism;
• welded frame;
• drive mechanisms.

Cleaning Technology

The grain mixture enters the feed section. A screw distributes the material across the width of the air chamber. Here, light impurities are separated. Thin grains are lifted by the air stream, settle in the settling chamber, and are discharged outside.

The cleaned material is divided into two parts and sent to upper and lower sieves. From here, the raw material is discharged via chutes into receivers located behind the sieve stands.

Sieving Machines from AO "Melinvest"

AO "Melinvest" is the only manufacturer of air separators of BIS and BLS models. It is more cost-effective to buy equipment directly from the manufacturer without intermediary markup. The units are adapted to Russia's climatic conditions and high levels of contamination in grain batches.

Cleaning machines differ from those of other manufacturers in that the separator's housing does not move back-and-forth but rotates. This achieves more thorough cleaning of raw material. View the catalog and specifications here https://www.melinvest.ru/catalog/pervichnaya-ochistka-reshetnye-mashiny/

Orders are delivered to the CIS and Russia by the factory or third-party transport companies.