Why Fugitive Dust Control is Vital for Air Quality and Mining Operations

By Ehab Abu-Ramadan, RWDI, Technical Director - Building Performance and Brian Sulley, RWDI, Technical Director - Principal

Fugitive dust emissions can create health, environmental, and operational hazards. Along with mines, sand and gravel pits, and quarries, potential sources of fugitive dust emissions include bulk material handling at ports and industrial facilities with processing operations and exposed storage piles. Containing a mixture of potential pollutants, this airborne particulate matter requires attention and robust mitigation strategies to safeguard human well-being, preserve ecosystems, and ensure sustainable operations.

How Dust Affects Air Quality and Mining Operations

Dust generation is common in mines and similar industrial sites. These are the top 3 ways in which unmitigated fugitive dust affects such sites:

Material Loss

Handling or wind erosion of raw materials (e.g., iron ore or nickel concentrate) can result in airborne dust emissions of products that could have otherwise been used or sold. The loss of such material may also lead to additional cleanup costs.

Equipment & Property Damage

Deposition and accumulation on equipment and nearby structures can lead to damaging effects, including a reduction in operational efficiency, more frequent repairs, and eventually equipment replacements. These effects can increase the operational cost of the facility.

Impact on the Surrounding Environment

Unmitigated windblown dust from sites may affect individuals working or living in the vicinity of the mining operations, plants, crops, and local wildlife. Excessive dust in the air can also reduce area visibility.

Challenges with Fugitive Dust Control in Mines and Industrial Sites

While controlling fugitive dust should be a priority for mines and industrial sites, several challenges are associated with selecting the optimal dust control method, the most critical of which are described in the following sections.

Dust Particle Characteristics and Weather Conditions

The characteristics of the dust particles can have a significant influence over their dispersal and transport and must be considered when developing fugitive dust mitigation strategies. For example, fine dust travels much further than larger dust particles. 

Higher winds, for instance, can spread dust over larger areas and dry conditions can influence how much dust is generated and emitted. Low humidity can also decrease the effectiveness of dust control methods that rely on water for suppressing dust, and operations in arid regions may be entirely unable to use water for dust suppression.

Site Topography and Structures

Complex natural topography, such as mountains, valleys, and cliffs, can make dust control for mining operations and other industrial sites more difficult. Wind in areas with challenging topography is more difficult to control or predict. Structures, such as tall buildings, can also divert wind, and therefore dust, in much the same way.

Thus, sites with nearby structures or complex topography will require a customized dust mitigation strategy.

Operational Activities

Some of the operational and production activities on mining sites, ports, and industrial facilities can emit significant amounts of airborne dust particulates directly proportional to the scale of the operation. Examples of such activities include:

Appropriate controls aimed at reducing this dust should be put in place to control dust, reduce emission rates, and lower the environmental impact of dust particulates, while also avoiding negative impacts to operational efficiency.

How To Develop Fugitive Dust Mitigation Strategies

In many instances, a customized site-specific dust mitigation strategy requiring the implementation of a specialized suite of tools is crucial for efficient dust control in mining and similar industrial operations. Here are the details on some effective tools that can be used to evaluate and mitigate dust emissions:

Evaluate Dust Emissions Characteristics with a Portable Wind Tunnel

A portable wind tunnel can be used to measure the windblown dust emission rates of different materials under varying wind and surface conditions. These emission factors can be used in numerical and physical modeling tools, such as air dispersion modeling and computational fluid dynamics (CFD) simulations, to predict the site’s dust emissions under varying weather conditions. Portable wind tunnels can also be used to calculate the effectiveness of different dust surfactants or other controls that can be applied to the surface of storage piles.

Evaluate Dust Impacts with Dispersion Modeling Techniques

Environmental regulations in most jurisdictions require the use of air dispersion models to demonstrate the site’s compliance with air quality limits set by the local governments. Regulatory models that calculate the dispersion of dust particulates from these operations must include consideration of local weather conditions, fugitive dust characteristics, and dust mitigation practices in place at each operation.

In many jurisdictions, the AERMOD dispersion model is the industry standard for predicting the transport and impact of dust emissions on the environment. In areas where complex terrain is not a concern, AERMOD is an effective tool for determining the potential impacts of fugitive dust emissions. These predictions help determine which fugitive dust sources are the greatest priority for dust control and the effectiveness of such controls. 

While several other government-approved dispersion model options exist, CALPUFF, an advanced air quality dispersion modeling system, has become the model cited in regulations related to evaluating the transport and impact of dust emissions in many parts of the world. This is, in part, because CALPUFF can consider wind directional changes within each hour modeled due to weather or terrain.

Avoid Dust Impacts with Operational Forecasting Systems 

Windblown dust fate is highly dependent on the spatial and temporal interactions of both mining activities and weather. However, adverse impacts can often be avoided with a proactive operational management tool that integrates weather forecasting, mining activity plans, and dispersion modeling.

Alerts can be sounded, and potential impacts visualized in a tailored online display, when forecasted weather is expected to cause major impacts for planned activities. Operations can then be rescheduled, or truck routes altered, to avoid exceedances and nuisances to surrounding areas.

Evaluate Mitigation Options with Computational Fluid Dynamics (CFD) 

Computational fluid dynamics (CFD)creates a virtual environment to simulate wind flows and dust emissions and transport throughout the site and its surroundings under the site’s meteorological and operating conditions. In dust modeling studies, CFD simulations are used to predict the site’s dust emitting parameters, such as surface wind shears, locations of dust scouring and deposition, and highlight potential problem areas. Simulations for industry projects, including mining operations, are intended to aid with the design of the dust control strategy to boost its overall efficiency. CFD simulation results provide guidelines for the selection and implementation of fugitive dust control strategies. Some strategies that can be evaluated using CFD include:

• the height, porosity, and location of the wind fence,
• configurations of berms and stockpiles, and
• surface stabilization technology.

As such, CFD simulations can:

• predict the efficacy of dust-control strategies ahead of installation, 
• modify the strategy to the site’s specific requirements, and
• reduce the risks of costly post-installation modifications.

Moving Forward with Fugitive Dust Control

Mining operations generate fugitive dust through resource and material extraction, storage and handling of the materials, or the transportation of these materials to markets. Air quality regulations are in place in most jurisdictions to prevent adverse impacts on the environment and human health.

As a result, mines and associated industrial sites are required to implement some level of fugitive dust control. Powerful tools, such as CFD, dispersion modeling, operational forecasting, and a portable wind tunnel can be leveraged to evaluate dust emissions and identify the most effective mitigation measures for each site.