World Grain - August 2018 - 72


Recent grain dust explosions in the United States



Number of explosions




Number of fatalities




Number of injuries




Ignition sources

Hot work, overheated motor,
smoldering, unknown (4)

Spark, overheated bearings,
unknown (2)

Overheated bearings,
electric spark, unknown (5)

Fuel source

Corn dust, mixed feed, baking
ingredient, unknown (2)

Grain dust,
unknown (2)

Grain dust,
unknown (5)

Source: Purdue University

tion from the grain stream. Another method for controlling
dust is to adjust the angle of spouting to reduce grain speed as
it moves from one bucket elevator to another conveyor. Grain
leaks from spouting can be problematic in terms of dust accumulation and chokes can overload a bucket elevator. To minimize the risk of a primary explosion, spout liners and cushion
boxes can be used to reduce the separation of dust in a spout
and to allow the incoming grain to hit grain accumulated in
the cushion box. On a bucket elevator, installing temperature
monitors on bearings allow operators to monitor for hazard
warnings and prevent the possibility of a spark from an overheated bearing.
Several options exist to prevent excessive accumulation
handling, can effectively lower dust emissions from moving grain by making the grain "sticky." With the addition of
a mineral oil, the dust remains "stuck" to the grain, minimizing the possibility of the dust dispersing in the air. A
second important prevention practice is a consistent housekeeping schedule. Whether dust accumulation is managed
by dry sweeping or with more sophisticated methods like
all points in the facility is important. Vacuums and compressed air have applicable standards and regulations and
have advantages and disadvantages.
Brooms, with antistatic bristles, are easy to operate and
have no regulatory constraints, but they require an operaWRU ZKLFK FDQ EH GLI¿FXOW WR ¿QG HVSHFLDOO\ GXULQJ EXV\
periods. No matter which method is used, chasing down
ledges is critically important.
The grain handling and processing industry has made good
progress in preventing grain dust explosions through enhanced engineering controls and interventions, improved
grain handling methods, and increased awareness of employees and managers about grain dust hazards. However,
grain dust explosions still occur more than they should. For

this reason, increasing the awareness and knowledge of
grain dust explosion hazards, their causes, and measures to
curtail the risk is important.
Until we reach the goal of zero grain dust explosions, the
effort of increasing awareness of grain dust hazards, preventive tools, and best practices will continue. The grain and feed
industry has made substantial progress, but the need continues
for highly trained workers and supervisors to understand and
apply safe practices in day-to-day operations.
Purdue University and Iowa State University have taken
a leading role in raising awareness of grain dust hazards.
Since 2015, Purdue University and Iowa State University
have led grain dust explosion prevention workshops across
the Midwest region of the United States and by request
elsewhere in the United States. The workshops include
topics such as dust explosion hazards, ignition sources,
housekeeping practices, sources of dust, and related topics
to provide a basic understanding of grain dust hazards.
An advanced workshop addresses grain handling and conveying equipment maintenance as it relates to grain dust, preventive
maintenance in grain and feed handling and processing facilities,
control mechanisms for use during unloading and grain handling,
controls of bucket elevator operations to limit dust, and use of
advanced engineering controls such as appropriate sensors and
explosion vents. The target audiences for both workshops are
of whom could potentially interact with grain dust. The four-hour
workshops are offered free of charge by Purdue and Iowa State
due to funding from an OSHA grant. If interested please contact
Professor Gretchen Mosher ( or Professor Kingsly Ambrose (
Dirk Maier is a post-harvest engineer with the Iowa Grain Quality
Initiative at Iowa State University. He may be reached at Co-authors of this article include:
Gretchen Mosher, Kingsly Ambrose and Samuel Cook.
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