Page 50 - HUB-4 Magazine Issue 89

Quarrying
lower speed will reduce fugitive material release, since the potential for fugitive material release is directly proportional to belt speed and capacity. The lower CEMA recommended belt speeds should be used in the first iteration of the design. Then additional iterations can be tried by changing the belt width, trough angle and belt speed to arrive at a reasonable solution.
Discharge Chute
For a capacity increase, the discharge chute will need close review. The trajectory path should be plotted so that the stream of material impacting the chute does not create a situation where there is zero or negative vertical velocity on impact with the chute. If the material can stay suspended at the impact location, it will increase the chance of buildup and blockage of the chute. If the angle or liner is changed, it must not create a slow flow situation where material backs up and accumulates in the chute. The discharge chute cross sectional area should be a minimum of 4 times the cross-sectional area of the loose bulk solid.
Raising belt speeds and volumes have consequences for transfer chutes and cleanup. © 2024 Martin Engineering
Receiving Chute
The design of the loading chute and skirtboards requires close attention to detail to minimize fugitive material release. CEMA uses 2/3 of the belt width for the inside dimension of the loading chute skirtboards, regardless of belt width. Idler fouling and spillage can happen when uneven loading causes the belt to drift to such a degree that there is an opening between the inside of the chute wall and the edge of the belt where material can escape. Best practice in design considers the amount of allowable mistracking plus the thickness of the sealing system to determine the distance from the edge of the belt to the outside of the skirtboards as the minimum dimension on each side. [Fig. 4]
Maintenance Access
If you upgrade your capacity but can’t access it for maintenance or cleaning, what have you accomplished? This detail is often overlooked. Any upgrade plan should include work platforms and upgraded access. Make sure all the old piping conduits and unnecessary structures are removed. Evaluate guarding and lighting to make inspections easier and more accurate. Provide the necessary power, compressed air or vacuum utilities needed for maintenance or cleaning.
Figure 4 - Mistracking Allowance + Sealing System Allowance x 2 = Skirtboard Width © 2024 Martin Engineering
Having safe and available access to components is part of design best practices. © 2024 Martin Engineering
Conclusion
There can be a large benefit to upgrading when the entire system design is considered. There should be an expectation of increased productivity. Additional benefits should include reduced fugitive material release by improved passive dust control and belt cleaning, saving on maintenance time due to improved access and a reduction in safety incidents due to reduced cleanup and maintenance-friendly changes.[2]
References
[1] Belt Conveyors for Bulk Solids, 7th edition, Conveyor Equipment Manufacturers Association, 2014
[2] Foundations for Conveyor Safety, Martin Engineering, 2010, chapters 31-34, 2016
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www.hub-4.com Nov/Dec - Issue 89