Properties of Dry Bulk Solids and Challenges of Handling Them

There are hundreds of powders, granules, and pellets that are regularly transported in bulk. Each has its own characteristics that factor into how readily it moves along a belt conveyor as well as precautions handlers must take with it. Cambelt's material handling systems are built to meet the challenges miners, farmers, teamsters, and factory workers have to deal with every day. Here's how we address common problems in moving various bulk materials.

Very Free-flowing Material
Dry bulk solids can sometime behave very fluidly. Some materials flow more than others as a result of friction and other factors. Materials like hulled rice, textile fiberglass, and dry silica sand are notoriously free flowing (they have a very low angle of repose). This can make them difficult to contain and move along a conveyor, especially when inclines are involved. Specialized belts like Cambelt's CamFlex and CamWall aid in preventing lateral or backward flow using flexible sidewalls and strategically placed cleats along the surface of the belt. In fact the CamWall belt, with its substantial cross cleats and attachable buckets, can move very free-flowing material vertically.

Sluggish Material
Other bulk materials are very sluggish. For example, the collected dust from grains, called stive, has an incredibly high angle of repose. Irregularly shaped items like wood chips are also resistant to flowing. In these cases, help must sometimes be given to get these materials onto the belts. Hopper railcars and many storage silos encourage flow using deeply sloped bottoms to allow for easy unloading. In flat bottomed storage facilities like many domes, special dome reclaim systems help pull resting material toward discharge points.

Packing or Caking
Some materials have the tendency to pack together under pressure or when allowed to settle. This can be a problem when moving from storage as well as on the conveyor itself, especially if continuous flow is required. Packing is a frequent challenge for moving materials like bentonite, sodium sulfite, zinc oxide, soaps, wet sugar, and sand used in sand casting. The intermittent nubs on the CamFlex belt encourage even distribution of product to help resist packing and caking. In dome storage scenarios, Cambelt's dome reclaiming systems are effective at removing heavily packed materials as well.

Easily Aerated or Wind Swept Materials
Calcined petroleum coke, fly ash, textile fiberglass, kaolin, dry paper pulp, and other dry bulk solids are liable to blow away or produce clouds of dust when being moved. This can be harmful to the environment and workers, not to mention the loss of product. The best solution for this problem is often to simply enclose conveyors where these materials are likely to fly away. Cambelt offers enclosed versions of all its conveyor systems, as well as boot lifts to allow dust-tight joining with railcar hoppers and retractable discharge spouts.

Harmful Dust or Fumes
Whenever you're moving chemicals like asbestos, arsenic oxide, benzene hexachloride, or anything lead-based it's essential to make sure toxic fumes and dust are contained. Besides Cambelt's fully enclosed, dust-tight conveyors and accessories, it's important to keep a well ventilated and circulated facility and to provide all workers with proper safety gear. Where dust can be explosive, such as grain silos, dust suppression systems can be employed.

Degradable Material
And of course there's the problem of taking care of fragile bulk products during handling. Bulk handling can be rough on materials. For products susceptible to damage during shipping such as almonds, shale, and wood charcoal; rubber belting is the way to go. And the fewer transitions between belts the better. Cambelt's conveyors can be as long as needed. Our L and Z configured conveyors allow transferring between horizontal and angled planes using one continuous belt. This can reduce the jostling of fragile products and help keep them in better condition to the end of the journey.

Contaminable Material
Bulk cargo handling can take products through various uncontrolled environments. Every surface the material touches can be a potential source of contamination. With food products including grains, vegetables, and nuts; care must be taken to avoid cross contamination. Other products such as polystyrene must be kept to a certain level of purity as well. Cambelt offers sanitary options for conveyors including rubber belting that is white and oil and fat resistant to make them easy to clean. The structure of our conveyors can be built in sanitary stainless steel and of course enclosed to keep out airborne contaminants. Obviously the best protection against contamination is for operators to carefully clean conveyors between uses and to avoid using the same conveyors for materials liable to cross contaminate.

Cambelt understands the difficulties of handling all sorts of bulk materials and we've engineered solutions into each product we manufacture. We also have a great deal of knowledge about the properties of different dry bulk solids we're happy to share. To get a custom conveyor or reclaiming system for your operation, request a proposal.

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