CONVEYOR TRANSFER CHUTES FOR DUST CONTROL
If your bulk material handling operation is struggling with dust, the transfer chutes you’re using might be part of the problem. West River Conveyors engineers transfer chutes for bulk materials ranging from coal and potash to ore, salt, and fly ash. These are designed and built for durability, reliability, and safety, and dust control is a major part of meeting those goals.
GENERATING DUST AT THE TRANSFER CHUTE
Dust is created when material waterfalls over the end of a conveyor or drops into a hopper. Along the way, it hits the walls of the enclosure, and some breaks up. The moving stream of material draws air in with it, and that carries smaller particles up and away. This airborne dust creates serious health risks, especially in enclosed spaces, and ends up coating surfaces around the transfer chute and further afield.
TECHNIQUES FOR CONVEYOR DUST CONTROL
Some material handling operations use dust suppression techniques — water sprays in particular — to remove particulates from the air and keep them on the material being conveyed. These “active” dust control methods are costly to run, may require water treatment, and leave the material being conveyed wet.
Passive dust control methods focus on keeping the dust within an enclosure, and most importantly, minimizing the amount produced. This is achieved through careful attention to transfer chute design.
DUST CONTROL THROUGH TRANSFER CHUTE DESIGN
Two passive dust control methods used by West River Conveyors are:
- Hood and spoon transfer chute designs
Skirts are heavy-duty rubber strips that fill the gap between the bottom of the discharge chute and the lower conveyor. Adjustment is critical to minimize lower belt wear while keeping dust within the chute enclosure. The skirts themselves will wear and need periodic replacement.
Skirts are almost always used with rock box style transfer chutes. These direct material down onto the lower belt but there are many impacts and hence high levels of dust generation.
Hood and spoon transfer chutes combine two material handling devices within a single enclosure. (Some applications may need only the hood or the spoon.)
Protruding past the end of the upper conveyor where the material waterfalls, the hood directs the stream downwards. This creates a more controlled flow while minimizing impacts.
Placed immediately over the lower conveyor, the spoon takes the falling material through an arc before depositing it on the belt. Curving the material flow this way achieves two things:
- Greatly reduces impacts as the material falls
- Gets the material moving in the same direction and at roughly the same speed as the lower belt
For the highest level of dust control, hood and spoon transfer chutes are still fitted with skirts. However, as far less dust is generated there’s less need for contact between skirt and conveyor so both last longer.
OTHER HOOD & SPOON TRANSFER CHUTE BENEFITS
In addition to creating dust, with the rock box design, it’s difficult to center the material on the lower belt. This leads to spillage and off-center loads. Combined with the high loads caused by the vertical drop, the result is accelerated wear in the conveyor system and reduced material yields.
Rock box transfer chutes usually incorporate sacrificial abrasion-resistant sections to take the brunt of the impacts. These wear and need periodic replacement, which causes downtime on the conveyor system.
The hood and spoon design of the conveyor transfer chute offer five significant advantages:
- Less dust generated (and less material wasted)
- Easier load centering
- Reduced material spillage
- Lower belt loading
- Less maintenance
DOWNSIDES TO HOOD & SPOON TRANSFER CHUTES
With their more complex design and construction hood and spoon transfer chutes cost around 50% more than straightforward rock box designs. However, many users find they more than recoup the additional outlay through reduced material loss and maintenance.
In cost-sensitive applications, some savings are realized by using either just the hood or just the spoon. If interested, contact us to discuss your application.
In space-constrained applications, especially those with low ceilings, there may not be enough height for a hood arrangement. Here the spoon alone will provide a proportion of the benefits (and save money.)
TRANSFER CHUTE DESIGN CONSIDERATIONS
Materials like potash, salt, trona, ore, and coal all have different densities and flow behavior. Each transfer chute must be designed for the material being conveyed.
Factors taken into account during transfer chute design at West River Conveyors include:
- Material characteristics (density, how it flows, particle size, and distribution)
- Material flow rate (velocities and tons/hr)
- Impact angles
The goal in every case is to achieve the target throughput rate material stream while minimizing impacts and preventing blockages. We make extensive use of sophisticated software applications to do this but there’s no substitute for our decades of conveying experience.
COUNT ON WEST RIVER CONVEYORS TO DELIVER
We’ve been engineering overground and underground conveyor systems for demanding clients in challenging industries since the 1980s. Our experience ranges from coal conveying to transfer conveyors and fly ash remediation systems.
If your business involves moving aggregates over extended distances, we can provide conveyor belts, structure, and ancillary equipment that will give you the durability and performance you need. We can integrate with existing systems and we offer an extensive spare parts service. Our on-site conveyor belt assessments help clients avoid breakdowns and keep their systems running at peak performance.
If you need conveyor expertise, we can help.