Published in the August 2006 American Longwall Magazine

Westbrook, a dust management specialist and technical consultant with nearly three decades of experience in the topic, conducts seminars throughout the country to educate industry professionals from both the underground and surface sectors on managing fugitive dust. That management, he says, must go further than the most commonly-used method, plain water, to the utilization of foam and water/surfactant mix sprays.

While the typical plain water option costs less, he said, there are several disadvantages that could end up costing mines more in the long run. Because coal dust particles inherently carry a static charge, water alone is only minimally effective – reducing only 25-50% of fugitive dust.

Westbrook offers two analogies for this occurrence: the repelling nature of two small magnets, and observing the beading of water droplets (rather than surface penetration) on dry soil.

Other concerns like the freezing, plugging and buildup on transfer points and crusher areas when using plain water can aggravate problems and slow production, or a loss of control can be suffered along the conveyor due to dust disbursement on belt carry-back.

The most vital item to consider with plain water use, Westbrook noted, is that a loss of BTU – often at significant levels – can be suffered because the coal becomes literally saturated. This can sometimes result in a lower output sale price: “The more water you put on, the more you degrade … BTU value.”

Foam and surfactants, however, are more effective and can actually counteract the intrinsic static when they are properly applied. Compared to plain water, this alternative adds only .1-.5% moisture to what is being produced and processed and is a more economical option to acquiring fog systems and/or collectors.

The surfactant method also lasts longer, so even beyond the point of application, such as at transfer areas, the solution still works. Depending on the chemical composition of a specific formula, said Westbrook, surfactants can have longer-lasting formulas or compounds with no residue.

The BTU is also left relatively intact with foam and surfactants due to the lower moisture levels. In fact, surfactant sprays typically use between 1 and 1.5 gallons, or 0.5%, of water per ton at a 1:1000 surfactant-to-water dilution ratio and foam dust suppressants come in even less at 0.2 gallon, or 0.1%, of water per ton at a 1:100 surfactant-to-water dilution ratio, he pointed out.

Unlike water, foams and surfactants actually will reverse the charging static properties of the dust, he said, allowing agglomeration of the particles to occur and reducing the environmental, health and safety hazards.

While plain water is inexpensive, the effectiveness of the foam or surfactant alternatives results in increased efficiency and, in the end, a more economical choice for operations.

Westbrook said many operations inquire about the cost of effective dust suppression at their mine.

He feels this question should be rephrased to “What is the real cost of ineffective dust management?” because that is the position many operations, unfortunately, are in.

“Yes, it costs a little bit more to use a surfactant or a foam, but it saves you more – probably 10 times more in the end – with the effects it has on your product.”