Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2009
Publication Date: 7/1/2009
Publication URL: http://naldc.nal.usda.gov/download/37972/PDF
Citation: Mina-Boac, J., Maghirang, R.G., Casada, M., Wilson, J.D., Yoon-Sung, J. 2009. Size Distribution and Rate of Dust Generated During Grain Elevator Handling. Applied Engineering in Agriculture. 25(4):533-541. Interpretive Summary: Dust generated during grain handling can pose a safety and health hazard and is an air pollutant. Fifty percent of the 245 reported grain dust explosions in the United States from 1986-2005 were in grain elevators. Due to the high organic content and small size of the particles, high concentrations of grain dust pose an explosion hazard. The size of the particles affects the minimum explosive concentration and the force of the explosions. In addition, prolonged exposure to grain dust can harm grain-handling workers’ health with smaller dust particles being carried deeper into the human respiratory system. To characterize the dust generated during handling of wheat and shelled corn dust samples were collected from the lower and upper ducts upstream of the cyclone dust collectors in the research elevator of the USDA Grain Marketing and Production Research Center. In the tests at an average grain flow rate of 54.4 t/h, the corn and wheat differed significantly in the dust size distribution and the rate of total dust generated. Shelled corn produced significantly smaller dust particles, and a greater proportion of small particles, than wheat. The corn produced more than twice as much total dust — 185 g/t of corn handled — than did wheat. These results improve our understanding of the health concerns of these grain dusts related to particle size and will be valuable for feed and grain handlers and grain elevator operators for evaluating and improving their handling and sanitation procedures to reduce their safety and health hazards and air pollution problems.
Technical Abstract: Dust generated during grain handling is an air pollutant that produces safety and health hazards. This study was conducted to characterize the particle size distribution (PSD) of dust generated during handling of wheat and shelled corn in the research elevator of the USDA Grain Marketing and Production Research Center and determine the effects of grain lot, repeated transfer, and grain types. Dust samples were collected on glass fiber filters with high volume samplers from the lower and upper ducts upstream of the cyclone dust collectors. A laser diffraction analyzer was used to measure the PSD of the collected dust. For wheat, the size distribution of dust from the upper and lower ducts showed similar trends among grain lots but differed between the two ducts. The percentages of particulate matter (PM)-2.5, PM-4, and PM-10 were 5.19%, 9.81%, and 34.1% of the total wheat dust, respectively. The total dust mass flow rate was 0.94 g/s (equivalent to 64.6 g/t of wheat handled). For shelled corn, the size distributions of the dust samples from the upper and lower ducts also showed similar trends among transfers but differed between the two ducts. The percentages of PM-2.5, PM-4, and PM-10 were 7.45%, 9.98%, and 28.8% of the total shelled corn dust, respectively. The total dust mass flow rate was 2.91 g/s (equivalent to 185.1 g/t of corn handled). Overall, the corn and wheat differed significantly in the size distribution and the rate of total dust generated.