The term “bulk handling” refers to the handling of bulk materials: anything that is not a discrete package but rather a granular, powdery, piece-shaped, or loose material. Bulk conveyor belts are strategic systems in sectors such as mining, cement production, steelmaking, agriculture, energy, and recycling.
In this context, the belt support rollers (also known as idler rollers in the bulk industry) must meet requirements that are very different from those of unit handling:
NUOVA OMEC rollers for bulk handling are used in all major sectors of heavy industry and the raw materials industry:
Quarry conveyor belts transport aggregates, gravel, limestone and abrasive minerals. LEP series extra-heavy-duty rollers with ceramic- or silicon carbide-coated shells ensure maximum wear resistance.
Conveyor belts for clinker, raw cement and finished products. Designed for highly dusty environments and the high temperatures found in kiln departments. Bearings with extended labyrinth seals and high-temperature grease. Rubber-coated shells provide resistance to impacts caused by falling material.
Conveyor belts for wheat, maize, soybeans and other grains in silos and ports. Stainless-steel or FDA-coated rollers for food-contact applications. IP67 protection for wet environments and frequent wash-down operations.
Conveyor belts for wood chips, pellets, sawmill waste and biomass used in cogeneration plants. Rubber-coated rollers provide improved grip and reduced noise. Special versions are available for environments at risk of combustible dust formation (ATEX).
For the central sections of the conveyor belt, where the material load is greatest:
For the empty side of the belt, return idlers require larger diameters and greater strength due to the belt’s tendency to become contaminated with the material being conveyed. They are available in smooth, rubber-coated, and disc-shaped (disc return idler) versions to allow the belt to clean itself.
Proper belt guidance is critical in bulk handling to prevent material loss from the edges and structural damage to the belt itself. NUOVA OMEC provides:
| Parameter | Available range | Notes |
|---|---|---|
| Load capacity per roller | 100 to 1,500+ daN | Theoretical bearing life: 10,000 h |
| Shaft diameter | Ø25 to Ø60 mm | C45 steel, heat-treated upon request |
| Casing diameter | Ø89 to Ø159 mm (standard), larger sizes available upon request | S235 or S355 steel |
| Effective Length | From 300 mm to 2,400 mm and beyond | Custom-made for non-standard belt widths |
| Bearing Protection | 2RS, labyrinth, IP67, IP69K | Depending on the operating environment |
| Operating temperature | −30°C to +150°C (special) | Special grease for extreme temperatures |
| Casing Material | Rubber, PU, ceramic, CVS | Thickness 8–25 mm |
| Reference Standards | DIN 22112, ISO 1537, CEMA | Compliance with specific standards upon request |
The support roller (or load-bearing roller) supports the loaded belt in the upper lane, bearing the weight of the material. The impact roller is positioned at the point where the material falls (often with a thick rubber lining to absorb the impact). The return roller supports the empty belt on the lower path: it requires less load-bearing capacity but greater resistance to accumulated dirt.
The choice depends on the abrasiveness of the material (abrasiveness index or Mohs hardness), the belt speed, and the predominant type of wear (abrasion, impact, or corrosion). For minerals with a Mohs hardness of 4–6 (gravel, limestone), vulcanized rubber is sufficient. For higher abrasiveness (quartz, granite, Mohs 6–7+), alumina ceramic is the preferred choice. Silicon carbide is reserved for the most extreme conditions.
Yes, upon request, we can provide rollers that comply with the major international standards for bulk conveyor belts: DIN 22112 (Europe), ISO 1537, and CEMA (North America). Please specify the applicable standard when placing your order to ensure the components are configured correctly.
