Clearing the air with passive dust containment systems
CJ Ferguson presents an engineered approach to passive dust containment.
Conveyor belts are the lifeline of an industry that measures success on the constant movement of material. With this mandate comes a side-effect, visible dust and fines that can escape into the air. Dust not only creates an environmental hazard, but it also presents challenges such as increased maintenance costs, health risks for workers that are exposed to particulates and decreased conveyor lifespan.
In the US, the Mine Safety and Health Administration (MSHA) recently proposed a rule, ‘Lowering Miner’s Exposure to Respirable Crystalline Silica and Improving Respiratory Protection’. It discusses the known adverse health effects, the current standard and the proposed rule for lowering exposure levels. It would require periodic sampling to verify that exposures are at or below accepted levels.
Conveyor solutions company Richwood acknowledges the necessity of a thorough strategy to control dust and spillage. Their method for minimising the negative impacts of visible dust and fines relies on an engineered, passive approach.
Importance of analysis
This passive method adheres to CEMA guidelines for transfer areas and industry best practices in containment. It also avoids the common drawbacks found in traditional methods of dust suppression such as misting or spraying either with water or chemicals or dust collection systems that require filters or continued maintenance.
A comprehensive analysis of a belt transfer is of primary importance, with attention to operating details. This includes evaluation of the belt elevation, considering factors like belt speed, drop heights, material characteristics, and output capacity. Special attention should be given to the Impact Zone where the load is introduced onto the receiving belt, ensuring that transfer designs do not impede material flow. Factors such as skirtboard width and length, as well as dust containment concerns, must be carefully addressed. A thorough evaluation of the application is essential before any recommendations can be made.
Belt elevation, properly established, is key. According to CEMA standard 575, the recommendation is for the belt to be fully transitioned with transition idlers before entry into the impact bed so that the belt is fully troughed.
Better belt support
Next, proper belt support must be in place. For Richwood, that includes impact saddles and cushion arc idlers in the load zone for impact protection and a proper foundation for successful sealing. The full arc design protects the belt from typical issues found in three roll idlers, like pinch points or gaps in support. Impact saddles and cushion arc idlers are designed to match the degree of trough.
For bulk material containment, canoe liners are put in place. This provides wear resistance for abrasive materials in the first line of defense against spillage. A secondary layer is then added with a skirting system, using either skirtboards or skirt clamps and a premium skirting rubber. All components should be designed for ease of use that facilitates well-maintained work areas.
Lastly, for complete dust control, a fully covered dust stilling system is added with multiple dust stilling chambers and dust curtains that allow the dust to “settle” before it leaves the load zone. The passive dust containment system eliminates the need for vacuums, filters, misting or spray systems or other additional equipment.
The simplicity of the system eliminates the issues of traditional methods and provides a practical, low maintenance solution to a common issue wherever there is material in motion.
Implementing engineered passive dust containment systems produces a ripple effect of positive outcomes. Less overall maintenance in the transfer area, reduced environmental footprint, decreased regulatory issues and positive health effects for employees along with minimised concerns associated with dust-related challenges.
CJ Ferguson is Senior Applications Engineer at Richwood.