Dust control has come a long way from using a hose as the primary solution to a dusty process.
Today, minesites are looking for proactive solutions to dust control.
Minesites are starting to look to weather bureaus in much the same way psychics look to the stars for guidance
Meteorological forecasts combined with atmospheric dispersion models and planned operating data are helping to determine the likelihood of dust on the surrounding environment.
Sinclair Knight Merz’s senior atmospheric scientist Jon Harper told Australian Mining that long range forecasts
and dispersion models allow minesites to find out what will happen tomorrow and react today.
“By using long range forecasts minesites are able to predict down to the hour what the weather conditions are going to be like and what the probability of dust is in the area, allowing the site enough time to get active and target the storm before it targets the site,” he said.
“A facility can either adjust their operational plans or implement dust reduction strategies to reduce the predicted impact.”
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 exceeds 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 in
cluding High Volume Air Samplers (HVAS), Tapered Element Oscillating Microbalance (TEOM) and Beta Attenuation Monitors (BAM).
While all three are able to provide information to a facility, they have the drawback of requiring 240 V power and are normally located at, or adjacent to, a sensitive receptor.
“This complicates the process of using these monitors as part of a dust management strategy as by the time an issue with dust is realised it is often too late to adequately rectify the situation,” Harper said.
According to Harper, light scattering techniques such as the MetOne E-Sampler are increasingly being used on facilities.
“These monitors can be operated using a 12 V power source which means it is possible to locate them in isolated locations and use solar power to charge a deep cycle battery,” he said.
“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 a computer will initiate a series of warnings including text messages or emails to mine management or specifically designed sirens.”
According to Harper, however, this is still a reactive method that requires the prompt attention of personnel to initiate the chosen controls and reduction strategies.
“It would be preferable to know in advance if the expected meteorological conditions are conducive to a facility having an issue at a receptor,” he said.
“Previously facilities have relied solely on generalised weather forecasts that are applicable to a large area and may not capture specific localised 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 understanding of the potential impacts.”
According to the Australian Bureau of Meteorology, minesites can, and often are, supplied with information specific to their location.
“We can tailor information to suit the specific needs of each industry,” Australian Bureau of Meteorology’s duty
forecaster Richard Russell told Australian Mining.
“The information supplied to each site is designed to their specific need and will talk in trends.
“We can predict the 10 minute wind speed average for a mine or, conversely, let them know what is likely to occur from hour to hour,” Russell said.
“Currently, we do forecasts for the La Trobe Valley, however, this isn’t so much with regards to the likelihood of
wind as it is to the likelihood of a fire.
Andre Wyzenbeek from John Morris Scientific agreed that a proactive solution was the best solution.
“Weather stations, on the surface, don’t seem that important. However, if you know that the wind is picking up then you can wet the areas that have low moisture levels,” Wyzenbeek told Australian Mining.
According to Wyzenbeek, measuring moisture is another method minesites are employing in their fight against airborne particulates.
“If you can measure the amount of moisture in the ground you can determine whether or not the area needs watering and thus if it is an area that could contribute to the dust problem onsite,” Wyzenbeek said.
“Water is a precious resource, as are wetting agents, so there is no point wetting something to prevent dust if the area is already sufficiently moist.
“It is just a waste of resources.”
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