Effective Dust Management Requires ‘proactive’ Approach

Aug. 29, 2008 - PRLog -- Although real time monitoring networks are essential to ongoing dust management, they are still a reactive management tool, says Jon Harper, Senior Atmospheric Scientist with Sinclair Knight Merz.

“To adequately reduce dust emissions a facility should strive to be proactive,” Mr Harper told delegates at the IIR Dust & Noise Management in Mining conference in Perth held in June 2008.

“One of the more effective proactive methodologies is to use meteorological forecasts combined with an atmospheric dispersion model and planned operating data,” he said.

“Using this information it is possible to determine the potential impacts on the surrounding region, including any sensitive receptors, up to two days in advance.

“A facility can then either adjust their operational plans or implement dust reduction strategies to reduce the predicted impact.”

Mr Harper said dust emissions from mining, material processing and ship loading operations are an environmental issue of increasing concern to government regulators and the community.

These could be generated from wind – when wind speed exceeded a threshold velocity –
or from mechanical processes that generate and potentially release particulate matter. These processes include material movement (such as grinding operations, dropping at conveyor transfer points, stacking, reclaiming and ship loading), blasting and vehicular movement over unsealed or dust laden surfaces.

Dust monitoring programs historically focused on ambient dust concentrations using a range of methodologies including high volume air samplers (HVAS), tapered element oscillating microbalance (TEOM) and beta attenuation monitors (BAM).

While all three can provide valuable information to a facility, the main drawback is that due to the requirement of 240v power they are normally located at, or adjacent to, a sensitive receptor (town, homestead), he said.

“This complicates the process of using these monitors as part of a dust management strategy as by the time an issue with dust is realized it is often too late to adequately rectify the situation.”

Mr Harper said a monitoring method gaining increasing usage is to establish a series of monitors that use a light scattering technique, such as the MenOne E-Sampler, around a facility.

“As these monitors can be operated off 12v power it is possible to locate them in isolated locations and use solar power to charge a deep cycle battery.”

The dust concentrations and meteorological parameters recorded by the monitors are relayed to a computer for processing. If the concentrations could result in adverse impacts, then the computer will initiate a series of warnings including text messages or emails to mine management or specifically designed sirens.

However, Mr Harper said it was still a reactive method requiring the prompt attention of personnel to initiate the chosen controls and reduction strategies initiated may be a little too late.

“It would be preferable to know in advance if the expected meteorological conditions are conducive to a facility having an issue at a receptor.

“Previously facilities have relied solely on generalized weather forecasts that are applicable to a large area (such as the south west of Western Australia) and may not capture specific localized meteorological events such as katabatic winds and the timing of sea breezes.

“With advances in our understanding of meteorological parameters, the development of reliable forecasting software and the increasingly powerful personal computers it is now possible to obtain accurate meteorological forecasts for specific locations.

“To use the forecasting to its full potential the meteorological data should be coupled to an atmospheric dispersion model and planned operating data to increase the understanding of the potential impacts.

“This type of forecasting requires a comprehensive understanding of the emission characteristics from all sources within a facility such as car dumpers, conveyors, transfer stations, crushing/screening, stacking/reclaiming, ship loading, windblown dust from exposed areas and stockpiles, and wheel generated dust from roadways.

“This type of advance dispersion forecast allows a facility to examine potential impact on the surrounding region, including any sensitive receptors, and either adjust operations or implement dust reduction strategies to reduce the predicted impact.”

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