Controlling dust and carryback at belt conveyor discharge points

Retroactively installing equipment to minimize carryback can improve belt conveyor safety and efficiency, reduce operating and maintenance costs, and increase equipment life.
Jan. 22, 2026
4 min read

Key Highlights

  • Increased belt speeds and material volumes can lead to carryback, spillage, and dust, necessitating improved cleaning and maintenance strategies.
  • Proper installation and regular inspection of cleaners, tensioners, and belt components are essential to prevent failures and reduce operational hazards.
  • Dust from carryback can impair air quality, reduce visibility, and cause equipment fouling, highlighting the need for secondary and tertiary cleaning systems.
  • Prompt replacement of frozen idlers and rollers prevents belt mistracking, static buildup, and potential fires, ensuring continuous and safe operation.
Courtesy of Martin Engineering
A front loader clears spillage from a transfer point.

Production increases in bulk handling operations can result in increased belt conveyor throughput volumes and belt speeds. These increases can, in turn, cause carryback, spillage, and dust at conveyor transfer and discharge points. The term carryback refers to material that clings to a conveyor belt beyond the discharge point and spills along the belt’s return. 

Carryback and dust can present ongoing problems at conveyor discharge points for bulk handling operations. Efficient belt conveyor discharge requires a holistic approach, with several components working in tandem to thoroughly clean the belt. Such a holistic approach aims to extend equipment life, improve safety, and address the root causes of inefficiency and downtime that reduce production and raise the cost of operation. 

Reducing belt conveyor carryback 

Primary cleaners or scrapers can fail for many reasons, but failure is usually caused by:

  • Increased belt speed or material volume for which the blades are not specified.
  • Changes in material type, size, or properties for which the blades are not specified.
  • Difficult access that prevents regular inspection and servicing.
  • Policies or schedules that allow blades to go beyond their service life.
  • Improper installation of the blade, tensioner, and/or assembly.
  • Inferior design or materials for manufacturing the blade.
Courtesy of Martin Engineering
Cost versus effort for cleanup in discharge zones

Cleanup is always needed, but this graph shows
that proper belt cleaning reduces the cost of operation.

Material spillage from carryback can accumulate quickly and encapsulate the belt. Cleaning spillage while the system is still running is extremely hazardous. Every year, catastrophic injuries or fatalities occur when workers cleaning around a running conveyor come into minor contact with a fast-moving belt and are pulled in. 

If equipment, such as a front-loader, is used for cleaning and bumps the conveyor frame, serious system misalignment can result, leading to belt mistracking. These hazards can be avoided by reducing the need for cleanup labor and thereby lowering operational costs. 

Mistracking can be caused by many factors, including a crosswind, off-center loading, or a frozen idler. A drifting belt can be a major cause of carryback at the discharge point, if the blade is not centered on the head pulley. In this instance, adhered material bypasses the cleaner and becomes carryback. 

Courtesy of Martin Engineering
Martin CleanScrape belt cleaner

Modern belt cleaners like Martin's CleanScrape reduce maintenance and improve safety. 

Installing a tracker at a location equivalent to 3 to 4 times the belt width before the discharge zone will ensure that the belt is centered on the head pulley. Also consider installing a modern cleaner, such as a Martin’s CleanScrape primary belt cleaner, which has 4 times the life of traditional blades and requires no retensioning or additional service after installation. This reduces maintenance and significantly improves safety. 

Controlling dust at belt conveyor discharge points 

Carryback is a major source of fugitive dust because much of what bypasses the primary cleaner blade is fine material embedded in cracks and divots in the belt. Excessive dust emissions reduce air quality and can result in workplace safety violations. It can also limit visibility, cover signage, and discourage access required to maintain system health and efficiency. 

Courtesy of Martin Engineering
Secondary and tertiary belt cleaners

Secondary and tertiary cleaners greatly reduce dust emissions along the belt return. 

The dust and fines can also easily migrate into the conveyor’s return rollers and takeup pulleys, fouling the bearings and causing them to seize. A frozen idler or roller increases belt friction, leading to mistracking as well as static and heat, which are major causes of belt fires. Frozen idlers and rollers must be replaced promptly, requiring unscheduled downtime, which reduces production and increases operating costs. 

Installing secondary and tertiary cleaners will ensure that the belt is thoroughly clean on the return. To avoid buildup on the catch slope leading to the transfer chute, consider adding a vibrating dribble chute. Also, installing belt trackers or crown rollers along the lower belt path will help ensure alignment on the return.

About the Author

Daniel Marshall

Daniel Marshall

Process Engineer at Martin Engineering

Daniel Marshall is a process engineer at Martin Engineering and has been with the company for nearly 20 years. He has been instrumental in the development and promotion of multiple belt conveyor products and is widely known for his work in dust suppression. Marshall received his Bachelor of Science degree in Mechanical Engineering from Northern Arizona University.

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