Mechanical Devices for Seed Cleaning: A Review of Separation Principles, Performance and Emerging Pollution Free Technologies
Kapil Verma *
Department of Farm Machinery and Power Engineering, Swami Vivekananda College of Agricultural Engineering and Technology and Research Station, Indira Gandhi Krishi Vishwavidyalaya (IGKV), Raipur, Chhattisgarh, India.
B. P. Mishra
Department of Farm Machinery and Power Engineering, Swami Vivekananda College of Agricultural Engineering and Technology and Research Station, Indira Gandhi Krishi Vishwavidyalaya (IGKV), Raipur, Chhattisgarh, India.
*Author to whom correspondence should be addressed.
Abstract
Cleaning converts a threshed, shelled or decorticated lot into a saleable product, and the device chosen depends on the property separating the wanted fraction from the unwanted one. This review organises that evidence by property: aerodynamic devices (terminal velocity), screens (size), indented cylinders (length), spiral separators and inclined drapers (shape and surface texture), gravity tables (density), magnetic and electrostatic separators (roughness and conductivity), and optical sorters (colour). Two findings emerge. First, the aerodynamic route dominates the literature, delivering cleaning efficiencies of 85 to 98 % for air screen and pneumatic units, but at the cost of a fan, a power source and airborne dust, with respirable dust of 3.2 to 10.5 mg per cubic metre and respiratory symptoms in 33 to 47 % of exposed workers - a documented occupational cost of that performance. Second, the friction based inclined draper separator, needing no fan, is almost absent from the primary research literature: no peer reviewed study reports its cleaning efficiency, capacity or governing variables for any oilseed. A device matching air screen performance without the dust burden is technically plausible, but the quantitative basis for designing one for decorticated groundnut the effect of deck angle, belt speed and feed rate on cleaning efficiency and kernel loss has not been established.Keywords: Seed cleaning, separation principles, air-screen cleaner, inclined draper separator, occupational dust, groundnut