Martin Engineering tackles fugitive material from conveyors

Although fugitive materials cannot be completely eliminated from bulk material handling conveyors, the issue can be effectively managed, leading to cleaner, safer, and more productive operations.

The symptoms of a failure to control fugitive materials include unplanned downtime, excessive cleaning costs, premature equipment failure, regulatory violations, and safety incidents. Addressing these symptoms with workable, long-term solutions will enhance performance, housekeeping and safety, and boost profitability.

When material ‘goes rogue’

The nature of fugitive material problems from any conveyor is indicated by the location and particle sizes of the accumulations. Fugitive materials are generally categorised into spillage, leakage, dust, and carryback.

Spillage escapes the belt and collects under the conveyor in both the loading and discharge zones. Piles of spillage accumulate rapidly and occur due to overloaded belts, mistracking, and insufficiently sealed loading and discharge zones. This is best remedied with a skirtboard liner. A wearliner and a canoe liner protect the enclosure from abrasion wear.

Leakage seeps, slowly accumulating in piles. The source of the leakage may not be immediately apparent. Apron-Seal™ dual skirting along the skirt board rides the belt, creating a seal material from dust emissions.

Dust commonly uses turbulent air to escape at the transfer point. In some studies, working in a dusty environment reduces worker productivity by as much as 20%.² Combustible dust presents fire and explosion hazards, along with health and safety risks. A modular transfer point kit creates a loading zone, settling zone, and stilling zone, separated by curtains, that control air flow and allow dust to settle back into the material stream.

Carryback refers to fine material that adheres to the belt surface or gets trapped in imperfections after passing the belt cleaners. At the discharge and along the belt’s return path, this material falls beneath the system, generating dust and accumulating, sometimes encasing the belt and rolling components.

Best practices for better material control

A common production ‘upgrade’ is to increase the speed of the belt. Fugitive material problems are roughly proportional to the speed of the conveyor (or tonnage). If the belt speed is doubled, the fugitive material problem and cost of operation (clean up, maintenance, equipment replacement, etc.) may also double.

There’s an old adage: “you can’t fit 5 lbs in a 1 lb bag.” Careful consideration must be given to capacity calculations, the angle of belt incline, transfer point design, and access for cleaning and maintenance. To enhance control of fugitive materials, it is advisable to derate the capacity to 80 – 90% of the theoretical capacity and employ slower belt speeds. Loading at an angle of less than 5° and reducing the incline will help minimise flooding and material rollback at the tail.³

Designing a longer and taller skirtboard enclosure with dust curtains will help control airflow and dust emissions. Access for cleaning and maintenance can reduce downtime by 33% and significantly decrease exposure to hazards. If future capacity increases are likely, they should be planned for in the initial design.

Case study – Western Brazil

A bulk handling operation in Brazil, located near a resort area, was facing public outrage due to dust and spillage that were staining the beautiful sandy beaches a deep red. The mill was confronted with daily fines and the risk of closure if the issues were not resolved.

The main focus was on repairing transfer points, replacing idlers, and alleviating some of the most significant material flow bottlenecks. The benefits were numerous. Spillage decreased from 2.8% to 0.8% of tonnes conveyed, idler life increased by 30%, belt life improved by 25%, and safety incidents and near misses were dramatically reduced. Operators noticed that most complaints shifted to the need to mow the grass that grew back underneath the structure.

However, the most significant benefit was the improvement in conveyor availability, enabling a 33% increase in production without expanding the raw material yard’s receiving and storage capacity.

Conclusion

Managing fugitive material is a more economically and operationally sound choice than merely chalking it up as ‘the cost of doing business’. The effect that spillage, dust, and carryback have on an operation is a tangible reminder of unnecessary inefficiency. By working with experts and installing modern solutions to age-old conveyor problems and practicing state-of-the-art maintenance, operators can significantly improve safety in the workplace and dramatically reduce the cost of operation.

References

1. ‘Belt Conveyors for Bulk Materials’, Conveyor Equipment Manufacturers Association (CEMA), 7th edition, (2021).
2. HUBBARD, DW., ‘How to Measure Anything, Finding the Value of Intangibles in Business’, John Wiley & Sons, (2010).
3. 3. COSCIONE, M.; Swinderman, RT., ‘Swinderman Scale of Fugitive Material Measurement’, Measurement of Fugitive Material for Belt Cleaning Assessment, ENCOM, (2018)

Read the article online at: https://www.globalminingreview.com/handling-processing/27062025/martin-engineering-tackles-fugitive-material-from-conveyors/