Rotary spiral separator in soybean seed processing

ABSTRACT Although static spiral separators are efficient in removing particles of varying shapes and densities, they often discard seeds of high physiological quality. This has led to the emergence of devices that enables rotation, thus allowing more precise control over separation of seed fractions. The objective of this work was to assess the physical and physiological quality of soybean seeds separated into qualified and discarded fractions by a rotary spiral separator. The device used for the tests operated at different rotation speeds, processing up to 1.2 Mg h-1. Twenty-seven 30 kg seed bags were used. Treatments consisted of two factors: rotation speeds (null, 5, and 10 rpm) and feed flow rates (0.3, 0.6, and 1.2 Mg h-1), with three replicates. Soybean seeds of the CZ 37B51 IPRO cultivar (2022-2023 crop season) with 13% moisture content were used. The null speed resulted in the highest seed discards (up to 40%), especially at the highest feed flow rate. A speed of 5 rpm also resulted in high discards. A speed of 10 rpm with feed flows of 0.3 and 0.6 Mg h-1 resulted in better performance, reducing discard and improving the fraction of qualified seeds, although it may compromise the quality of these seeds. A speed of 10 rpm reduced the discard of high-quality seeds, and a flow of 1.2 Mg h-1 was less efficient, resulting in a higher discard of high-quality seeds compared to lower flows.