Airborne dust poses health, safety and environmental risks. Engineering Services & Supplies’ (ESS) range of dust suppression sprays, sealing and belt support systems and chute design provides a customised solution to reduce its clients’ dust problems.
Dust is common to all bulk material processes. Dust is generated wherever there is bulk material movement.
Dust from 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 workers and the townships supporting them.
Prolonged exposure to the fine dust particles poses serious health risks, including skin, eye and lung irritation. Dust is especially hazardous when inhaled. It can contribute to a range of health issues including shortness of breath and severe lung diseases, exacerbate existing respiratory problems and in some cases are carcinogenic.
Beyond that, dust settles on and then abrades moving machinery components, causing accelerated wear, which in turn increases the frequency of premature replacement and associated labour costs.
Dust also decreases overall visibility around the mine site and creates slip, trip and fall hazards. Some materials produce dust that has a heightened explosive risk when exposed to a spark.
Additionally, dust causes environmental concerns. In some cases, it can damage ecosystem diversity, forests and farm crops and change the nutrient balance in soil and water.
Breaches of occupational exposure limits and environmental protection legislation can result in penalties and site closures.
ESS accounts development manager and training instructor Tom Stahura has over 40 years of experience in the bulk material handling industry and uses this knowledge to guide the mining industry on dust suppression.
“When mine employees see dust, they may not be able to identify the source of the problem because they see it every day and are used to it, but we deal with dust and are able to diagnose the cause of the dust,” Stahura tells Safe to Work.
While each site has different challenges and expectations of dust management, ESS diagnoses and tailors solutions to solve each site’s dust issues.
“By partnering with our clients and going to the mine site, seeing what they are trying to describe allows us to take the experience gained to find the right mix (of solutions) for that client,” Stahura says.
ESS has a history of successfully designing, manufacturing and installing tailored dust control solutions for industrial operations. ESS examines the type of material, the source of fugitive dust, the design of the existing structures and the environmental conditions to determine the best dust control method.
Stahura suggests three primary ways to control dust: minimising air velocity and exposure to the material, increasing cohesiveness (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 in its dust control solutions.
Sealing conveyor load zones, transfer points, impact zones and settling zones can help mitigate dust issues. ESS examines the design and integrity of a conveyor transfer point and installs sealing and support systems to achieve better airflow and air control before considering water sprays or chute modifications.
“As a conveyor discharges its load, that material draws air in from above, so ESS aims to minimise the amount of free air getting sucked into the conveyor transfer chute in the first place,” Stahura explains.
“In some cases, spray systems are used at transfer points to increase the material’s cohesiveness, reducing potential dust particles.”
ESS’ dust suppression strategy reduces the amount of dust that leaves the skirted zone by controlling the air velocity. Reducing the air velocity that the product is exposed to also reduces the production of airborne dust.
“When there is dust moving with the top of the conveyor and in the same direction, it is important to slow that air down,” Stahura continues.
“When we control the airflow at a transfer point, we reduce the production of airborne dust and thereby minimise the need for costly collection or suppression systems.”
Sites that experience crosswinds during certain times of the year may need to apply dust hoods or sealing systems along the conveyor to reduce escaped dust.
In areas where the material is exposed and cannot be sealed effectively, ESS uses dust suppression systems.
Dust suppressing agents can be sprayed directly onto the material, the belt or the dust directly at transitional points at a mine site, including trucks, conveyors and rail cars, with most spray systems operating on a sensor.
Some systems may involve the use of liquid or foams to increase the mass of potential dust particles. Spraying the material directly increases the cohesiveness of the material and can act as a sealant to prevent dust from escaping the system.
“Dust sprays are often used at load zones and discharge points to help prevent dust production,” Stahura says.
“Wetting the belt’s surface can help the material to clump together to prevent particles from becoming airborne.
“Introducing moisture into the air attracts dust particles so that the particles gather enough mass that they will settle rather than be blown away to contaminate another area.”
In applications where water resources are limited, or the material cannot become overly moist, 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.
“Foam uses far less moisture than water drops by itself, with additives making the foam expand its surface area 100 times more than one water droplet,” Stahura says.
While dust creates a multitude of issues and it is essential to control these problems for health, safety and work environment, it also affects workers’ attitudes and their pride of the workplace.
“At the end of the day, you want to go to work in a place you can be proud of and feel safe in,” Stahura concludes.
This article also appears in the Mar-Apr issue of Safe to Work.