Dust management is an essential component of effective mine site maintenance. Safe to Work talks to ESS training instructor Tom Stahura to find out how it can be kept under control.
Mine site conveyor belts become a source of dust when bulk material movement creates very fine particles. If the particles are less than 500 microns, they can become airborne and travel vast distances before settling. Most dust is generated at transfer points, discharge points and load zones. Serious concerns arise when the dust becomes airborne and escapes to surrounding areas.
Contamination resulting from this form of fugitive material can cause environmental hazards that threaten flora and fauna on land over waterways and oceans.
Environmental protection legislation can result in penalties and closures.
Industrial operations such as alluvial iron ore mines (where the iron dust is very fine), mineral sands operations, coal mines and processing plants all pose a health risk to not only workers, but to townships supporting them.
The fine particles of dust pose serious health risks, including skin, eye and lung irritation. Dust is especially hazardous when inhaled as it can contribute to a range of severe lung diseases including black lung or asbestosis, while some types of dust are also carcinogenic. The risk to health varies depending on the size and nature of the dust particles.
Dust can also decrease overall visibility around the mine site, creating slip, trip and fall hazards, and impact regional flora and fauna if not adequately controlled. Some materials (coal, phosphates, fertiliser, and cement) produce dust that has a heightened explosive risk when the dust comes in contact with a spark.
Beyond the associated health and safety risks, dust settles on moving machinery, which increases wear and causes longer, more frequent shutdown periods and increased component replacement and maintenance costs.
While it is nearly impossible to stop the creation of all dust, however, it is possible to suppress, contain and collect it.
Engineering Services & Supplies (ESS) has a successful history of designing, manufacturing and installing dust control solutions for industrial operations. These solutions include airflow control systems, belt cleaning spray systems and dust sealing and containment devices that all help to reduce fugitive dust issues.
ESS accounts development manager and training instructor Tom Stahura has over 40 years of experience in the bulk material handling industry. Stahura explains that there are three primary ways to control dust: minimising air velocity around the material, increasing cohesiveness (i.e. stickiness) of the material, and making the dust heavier by increasing the particle size so that it will drop from the air.
ESS applies these principles to its dust control solutions. ESS examines the type of material, the source of fugitive dust and the design of the conveyor (including existing structures and belt accessories) to determine the best method of dust control.
ESS often uses spray systems, sealing systems and belt support systems to control fugitive material.
Spray systems may involve the use of liquid or liquid foams to increase the mass of the dust particles and increase the cohesiveness of the material. This can be sprayed directly onto the material, the belt or the air.
Spraying the material increases the cohesiveness of the material and can help to reduce material fracturing at transfer points. Wetting the belts helps the material to clump and become heavier.
Spray systems can also be sprayed directly on fugitive dust. “Using a fine spray to atomise the moisture in the air will attract more dust particles so that they gather enough mass that they will settle down,” Stahura explains.
In areas where using water needs to be conserved, ESS spray systems can use foam or other chemicals to act as a surfactant, cutting down on water usage while still having sufficient surface area to remain effective.
The design of the transfer point can increase dust issues. For example, air can hit the skirted area of a conveyor and you can see the cloud extend out from the skirt zone.
ESS examines the design and integrity of a conveyor transfer point and act accordingly to modify the shape of certain sections of the conveyor to achieve better airflow and air control, by installing sealing and support systems.
Dust curtains and dust bags are also installed to slow air movement for improved stability.
Mine sites should not overlook dust control. It offers personal safety, environmental and productivity, which benefits all stakeholders and the environment.
As Stahura concludes, “you want to go to work in a place you can be proud of”.
This article also appears in the January–March edition of Safe to Work.