Color sorting is a sorting technology of any bulk materials based on the product analysis by color. Recently this technology has been recognized by many Russian manufacturers.
Principle of separating by color was developed already in the middle of the past century, while the first color sorter was installed in London, 1947 by English company Sortex. Currently color sorters of various marks and configurations are produced by a number of companies all over the world, aiming at cutting edge know-how in electronics, optics, mechanics and pneumatics. These are high-precision machines, being easily operated and making outstanding sorting results- up to 99, 99% of output product purity.
Color sorting is widely used in food industry, especially where visual product control is demanded, like sorting of cereals, legumes and oilseeds, nuts, grass seeds and even frozen or dried fruits and berries. Color sorters successfully meet the needs of non-food industries, like recycling of glass and plastic, as well as sorting of wastes, salt and minerals.
Standard procedure of sorter’s operation can be described as follows.
Input product is loaded in the sorter via in-feed hopper. With the help of vibration the material flows along the chute to the distribution channels. Then the product gets into the inspection zone, where it is checked by the high-tech sensors or CCD-cameras. Sensors (or cameras), having received the reflected light from the selected material, generate electric signal for computer operating system.
Depending on the signals received from the optical system, the computer control system sends the command to open the pneumatic valve (the ejector) which blows away grains different in color. The good product directly flows into the good product hopper. The reject is blown off to the discharging hopper.
Most of the sorters have the re-pass option ensuring more accurate sorting of the grain and minimizing losses of the good product.