Dust content and adhesion characteristics of five corn samples

Authors: PLUMIER, BENJAMIN - Purdue University; ZHAO, YUMENG - Purdue University; Casada, Mark; MAGHIRANG, RONALDO - University Of Illinois; AMBROSE, R. P. KINGSLY - Purdue University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2020
Publication Date: 2/1/2020
Citation: Plumier, B.M., Zhao, Y., Casada, M.E., Maghirang, R.G., Ambrose, R. 2020. Dust content and adhesion characteristics of five corn samples. Transactions of the ASABE. 63(2):495-499. https://doi.org/10.13031/trans.13747.
DOI: https://doi.org/10.13031/trans.13747

Interpretive Summary: Grain dust explosions occur when dust accumulates beyond the minimum explosible concentration in a confined space and is exposed to oxygen and an ignition source. Facilities that handle grain can be at risk of explosion if dust particles are released during handling producing spaces with sufficient dust concentration for explosion. The adhesion force that holds the grain dust particles to the grain itself is an important factor in better understanding grain dust and mitigating the separation of dust from grain kernels. We used a centrifuge to separate the dust from the grain kernels and determine the forces required for separation. There was large variability in dust concentration between the five samples tested. After repeatedly centrifuging the samples, we found there was a subset of the total adhered dust removed at the lowest centrifuge speed (1000 rpm), followed by a second subset with much higher attachment strength that was only removed with centrifugation at 3000 to 4000 rpm. This indicates that a portion of the total grain dust is likely to be detached during any physical handling of corn, but that care should be taken that the impact velocities of grain kernels not grow high enough to release the additional quantities of dust that are more strongly attached. These results improve our understanding of how dust particles are removed from corn to cause dust cloud generation and will be valuable for grain handlers and grain elevator operators for evaluating and improving their handling procedures to reduce their safety and health hazards and air pollution problems.

Technical Abstract: Grain dust explosions are a constant threat to the grain handling industry. Explosions occur when dust accumulates beyond the minimum explosion concentration in a confined area and is exposed to an ignition source. Handling and grain unloading conditions that generate dust, minimum explosive dust concentration, overpressure from an explosion, and other factors that lead to grain dust explosion is well documented in literature. The adhesion force that holds the grain dust particles to the grain itself is an important factor in better understanding and mitigating their generation/separation from grain kernels. However, that adhesion force, how it is affected by grain quality, and how it is influenced by particle factors such as size and shape has not been adequately researched. A centrifuge separation technique was used to study adhesion forces of grain dust. Results showed large variability in dust concentration between the five corn samples tested in this study. The dust particle attachment strength ranged from 2.1E-8N to 4.6E-10N. Only the sample and sample centrifuge speed interactions had a statistically significant effect on dust concentrations recovered at a 5% confidence limit. Under repeated centrifugations, dust removed showed a bimodal distribution of attachment strengths with three of four samples tested showing a local minimum at 2000 rpm, and the other at 3000 rpm. This study helped understand the fundamental attachment strength behind dust separation from grain kernels. Investigating the size, shape and surface characteristics of dust particles with varying attachment strength is important to further understand their adhesion and/or separation mechanism.