World Grain - September 2013 - 102

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cording to the National Research Council. The lower dust loading and lower efficiency tend to balance each other.
Air pollution control devices should
be operated whenever there is grain
present. Check the equipment daily for
proper functioning, and fix any malfunctions quickly to minimize the amount
and duration of excess dust.
Schedule regular maintenance of control equipment, and keep equipment
logs with information such as dates of
inspections, maintenance procedures
and replacements.
oil suppression systems
Oil suppression systems have been
developed to prevent elevator explosions as well as control emissions.
White mineral oil, soybean oil or some
other vegetable oil is typically used.
In an oil suppression system, dust adheres to the oil added to the surface of
the grain. Physical forces can cause dust
particles to detach from the surface of
the grain. Suppression of smaller dust
particles is more prevalent because the
adhesion force for smaller particles is
greater relative to the acting physical
forces, according to the U.S. Environmental Protection Agency (EPA).
Effectiveness of oil suppression sys-

tems depends heavily on the point of
application, the EPA said. It should be
added as early as possible, preferably
before the grain is first elevated.
To ensure the oil is dispersed well, it
can be applied as a top dressing before
the grain enters the bucket elevator or at
other grain transfer points, or from below the grain stream at a grain transfer
point, using one or more spray nozzles.
Oil can also be added in the boot of
the bucket elevator leg, at the discharge
point from a receiving pit onto a belt or
other type conveyor and in a screw conveyor, according to KSU.
The amount of oil needed for dust
suppression varies depending on the
type of grain handled and the amount
of dust present. Adding more oil will
not substantially increase the amount of
dust suppressed, the EPA said.
As little as a half gallon of oil per
thousand bushels of grain can reduce
dust by up to 80%. Effective dust control can be achieved for up to six months
or for six to eight handlings of the grain
after the oil is applied.
maintenance
Once preventive processes are in
place, maintaining equipment is one of
the best ways to ensure dust emissions

are controlled. Make sure equipment is
operated according to manufacturer’s
instructions. This is especially true for
grain dryers, which can be the source of
many complaints from neighbors.
Inspect dryer screens before each
start-up, and do not exceed the recommended capacity for the amount of grain
passing through the dryer. Enclose grain
inlets and outlets to the dryer, and enclose as much of the dryer as is practical. Double check the screen perforations for column dryers and the screen
filter size for rack dryers.
In other areas of the grain elevator,
be sure to perform regular inspections
on all equipment and make needed repairs immediately.
Clean up indoor and outdoor areas such
as floors, roofs and decks to prevent accumulation of chaff and dust that can blow
around. In addition, clean up the yard,
ditches and curbs as needed to prevent accumulation of grain, chaff and grain dust.
Any grain spills on driveways or access roads should be cleaned up, and
unpaved roadways or traffic areas can
be watered to minimize the amount of
dust in the air.
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