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5
Introduction
Port operations where coal and other byproducts are routinely stored and handled outdoors are highly
prone to dust pollution. In addition to generating dust during the stacking, loading and transportation of
bulk materials, oncoming high-speed prevailing winds have the ability to generate dust by simply carrying
particulate from standing stockpiles.
While wind direction upon the stockpile is a main consideration when determining the position of a wind
fence, there are other key parameters, such as fence height, material porosity, and their relationship to
oncoming wind speeds that weigh heavily into material and installation support selection to achieve the
fences highest performance level. Examining and optimizing these wind fence parameters for the specific
site constraints will ultimately determine the value of the wind fence installation and its ability to prevent
particle uptake from the stockpile.
Dust will be generated by the impact of the wind on the coal stockpiles in the plant. Wind comes towards
the area and creates what is referred to as “particle uptake”. This is the pressure built on the pile as a
result of the wind forces that is high enough to lift the material from the pile and blow it away from the pile.
If a porous media is used some of the wind will bleed through the fence and leave an equilibrium in
pressure between both sides. The 100% wind speed will stay at the height of the fence, while the
reduced speed will bleed through underneath the height of the fence. This can be seen in the figure
below:
The important purpose of a wind fence is reduce the velocity of the wind that can create particle uptake.
Particle uptake does not occur unless the wind speed is above a threshold velocity, which is determined
by the type of stored material, moisture content, and the specific gravity of the dust particles. (EPA, 1995;
Mueller et al., 2015).
Once this threshold velocity is reached, the particles due to aerodynamic forces will have one of three
effects: rolling, saltation, or suspension. Rolling is the movement of the particle along the ground,
dependent on the wind velocity next to the pile. Saltation is the lifting of the particle due to the wind
velocity next to the pile returning the particle to the ground. Finally, suspension is the lifting of the particle
due to the wind velocity with the particle
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