Repeated Transfers of Soybeans in Pilot Scale Bucket Elevator Legs: Effects on Dust Particle Size Distribution and Shape Characteristics

Highlights The amount of soybean dust generated is higher during the first transfer compared to the succeeding transfers. The number of repeated transfers significantly affected the particle size and shape characteristics. The highest dust generation was observed near the hopper where grain agitation is at maximum. ABSTRACT. The movement of grain in large quantities generates grain dust, which poses significant health and safety hazards. We investigated the effects of repeated transfers, soybean grade, and bucket elevator feeding direction on soybean dust quantity, particle size, and shape characteristics. Two pilot-scale bucket elevators with different feeding configurations, front-feed and back-feed, were used to evaluate soybean dust characteristics, including particle size (circle equivalent diameter), particle size distribution, and shape characteristics (high sensitivity circularity, aspect ratio, and elongation). Dust samples were collected at multiple points on the elevators using glass fiber filters with a cassette assembly and air sampling pump. Particle size and shape analyses were performed using the Malvern Morphologi G3 SE via 2D imaging. A general decreasing trend in dust quantity was observed across both elevator types and soybean grades (U.S. No. 1 and U.S. No. 3). Repeated transfers significantly influenced key dust characteristics, including dust mass, particle size (CE diameter and D[V,0.50]), high sensitivity circularity, aspect ratio, elongation, solidity, convexity, and particulate matter fractions (PM4 and PM10). These findings enhanced the understanding of the effects of repeated handling on soybean dust characteristics, providing important values and insights for modeling dust detachment, suspension, generation, and explosion risks in grain elevators. Keywords: Bucket elevator, Grain dust, Particle shape characteristics, Particle size distribution, Repeated transfers, Soybean dust.