Preventing Frozen Bulk Material & Conveyor Belts
What to Know & Use This Winter
Steady, efficient production at a bulk material handling operation can involve more than controlling dust and having the right equipment for material containment and flow on the conveyor belt. Managing weather conditions also becomes a factor, especially in winter when they cause bulk material and conveyor belt freezing.
Because they have high levels of fines, bulk materials such as ore, sand, gravel, and coal can change into problematic masses when exposed to precipitation and extreme cold. Material that is frozen then behaves differently from material that is not. For example, bulk material freezing can:
- clog chutes
- make material break off in large, heavy clumps from storage piles
- cause the material to become highly difficult to elevate at steep angles
Other problems with material freezing during cold weather that might interfere with production could include:
- frozen residual material and masses in rail cars
- arching and ratholing from the frozen product in silos and bins
- slippage and inefficient handling of bulk material due to ice infeed systems
Material freezing also can become further pronounced by factors such as piles remaining exposed for long periods and rail-car shipments being delayed between the mine and the plant. Compounding the issue, deicing the frozen material can require extra equipment and labor and project delays or shutdowns. Dust control remains a concern as well, even when the material is frozen at the lowest temperatures.
The question for bulk material operators becomes whether to apply prevention or cure methods in dealing with frozen material, especially at the conveyor belt, where problems can ripple deeper into production. Using mechanical methods to address freezing problems – a cure strategy – can lead to longer unloading and handling time, lost revenue from slowdowns and shutdowns, and a back-up of material cars and rail sidings. Breaking up and re-crushing frozen materials with vibrators, car shakers, hydraulic rams, bulldozers, backhoes, and other heavy machinery can damage equipment and vehicles and be expensive to operate. Using compressed air blasters in silos can lead to increased costs and delays. Applying fire and other high heat for deicing may not always be a safe material handling solution.
The key to preventing bulk material and conveyor belt freezing is making the best use of solutions engineered to block it before it becomes a problem in need of a cure. It also helps to understand further the freezing issues that can be specific to the conveyor belt.
Solving Frozen Material Flow: Conveyor Belt Deicers
Freezing in the load zone impacts both the bulk material and the conveyor belt. Icy, heavy bulk material can become stuck or lodged as well as burdensome on the conveyor. In addition, when material freezes to a belt, it will cause problems at the conveyor’s head if the operation uses brushes for clearing material. In addition to gathering and filling with snow, conveyor belt brushes will not remove frozen particles from the bulk material.
A long static period in the extreme cold will often create an exceptionally low temperature in the conveyor belt. This can mainly be the case with rubber conveyor belts, which at temperatures below 32°F will become much less elastic and flexible and less resistant to wear. As the temperature continues falling, a rubber conveyor belt can become so rigid that it will no longer trough or pass around pulleys. In addition, the belt covers and the rubber inside the carcass can crack, and if the belt is frozen enough, the rubber can become so brittle that it shatters. Operations in the northern U.S. will often keep their conveyor belts running even in below-freezing temperatures. If they do not, the material inside the conveyor system can freeze to the pan and increase the load when the system starts again after a complete stop. The belt also can freeze to the pan and the idlers, which can wear flat spots that destroy the roller. At the same, keeping conveyor belts running in the extreme cold will not entirely deter issues from freezing. Ice can still form on the belt and decrease the friction. In this event, the head drum will spin in place because it cannot pull the belt. With chain conveyors, while they cannot slip as conveyor belts can, chains and material can still freeze to their pans.
Many traditional approaches to preventing frozen bulk material and conveyor belts can stop working or become much less effective when temperatures reach 0ºF to -10ºF. Conveyor belts also can start to harden at 20ºF, allowing bulk material to backslide.
Proactively stopping threats to production caused by frozen material and extremely cold conveyor belts can include conveyor belt deicers, which are agents applied to the bulk material surface before the onset of ice. The agents reduce the temperature needed for deposits to freeze, thus preventing them from freezing into thicker and heavier masses. Unfortunately, they also weaken the crystal structure of ice to make it easily fracture.
Conveyor belt deicers further restrict the bonds between wet bulk materials and cold conveyor belts and trap dust particles on material surfaces.
The proper amount of conveyor belt deicer is determined by variables such as:
- size of particles and percentage of fines
- moisture between particles on the bulk material surface
- temperature and precipitation during transit, conveyance, or storage
- the time between loading and unloading in transit or storage
- condition of the rail car at the time of loading (e.g., full of snow or residual fines)
Beyond its utility for conveyor belts, a good deicer can be applied to idlers, rollers, chutes, switches, and truck beds. It also will be non-corrosive and sprayable with an automated system – even in extreme cold – without a need for repeat applications.
Benetech Conveyor Belt Deicer
Designed for winter’s distinctive operating challenges, Benetech’s conveyor belt deicing spray systems apply freeze control agents developed with our advanced chemistry to:
- combat snow, moisture, and freezing at sub-freezing temperatures
- prevent ice build-up and frozen material
- discourage frozen material from sticking to the conveyor belt
- stop material slippage by creating friction, even on hardened, weathered, old, or steep belts
Benetech’s BT-955 conveyor belt deicer is a glycol-based, non-corrosive blend of freeze point–depressant side-release agents that inhibit the cohesive bonds between wet material and cold conveyor belt surfaces. In addition, they modify and weaken the crystal structure of ice to fracture readily.
The BT-955 conveyor belt deicer protects bulk material and conveyor belts down to -1°F. Our freeze control conditioning agents are also formulated to control dust by trapping particles on material surfaces to reduce dusting when offloading and handling even in extremely cold conditions.
Benetech: Your Ally in Bulk Material Handling
If you have a challenge with bulk material and conveyor belt freezing, Benetech already understands it and is ready to support you with the proper solution. If you would like to discuss further what our conveyor belt deicer can achieve for your winter production, contact us at (630) 844-1300 to speak with a specialist.
Posted in Conveyor Belts, and Maintenance