Choosing a Conveyor Belt for Bulk Materials: Types, Covers and Parameters

No Universal Belt for Bulk Materials

The belt is the most heavily loaded and costly consumable on a belt conveyor; a wrong type choice leads to accelerated wear, frequent stoppages and premature replacement. There is no universal belt, because abrasive ore, hot clinker, wet coal and chemicals require different constructions and materials.

Common Belt Constructions

Rubber-fabric belts, the most widespread, use several synthetic fabric plies bonded by rubber layers for strength and flexibility, suiting standard tasks such as sand, gravel, grain and medium-abrasion coal; ply count determines tensile strength. Steel-cord belts replace fabric plies with steel cords vulcanized into rubber, carrying high tensile loads on long main-line conveyors, with minimum elongation under load as the key advantage for long routes. Chevron belts have transverse cleats of varying height on the carrying surface that prevent material rolling back on inclines up to 30° and above, used on steep conveyors for ore, crushed stone and other bulk cargo. Heat-resistant belts use a special rubber compound that stays elastic when heated for hot clinker, cement and ash; selection must account not only for material temperature but also for continuous contact time. For coal mines and sites with stricter fire safety requirements, PVC/PVG belts with antistatic and flame-retardant properties conform to ISO 340 and are mandatory in underground workings.

Abrasive Rock: Ore, Crushed Stone, Gravel

High abrasion calls for a belt with a thicker top cover and a wear-resistant rubber compound; for large-lump material the cover's impact toughness must also resist drops of sharp lumps without tearing.

Hot, Wet and Sticky Materials

Beyond a heat-resistant cover, the carcass must resist degradation under prolonged heating, so fabric or steel-cord cores are selected with a temperature margin. Wet coal, clay and concentrate tend to adhere to the carrying surface, which requires a smooth, low-adhesion cover and cleaning equipment; combined with spiral cleaning rollers, this reduces return-side spillage and load on the return run.

Chemically Aggressive Materials

Fertilizers, salts and chemicals destroy ordinary rubber, so oil- and fuel-resistant or acid-resistant covers are used; account for both the carried material and possible interaction with product residue on the return run.

Key Parameters and Splicing

Width is chosen from lump size and required capacity, with the standard range of 400 to 2400 mm; for lumpy material the belt must be at least 3 to 4 times the maximum lump size to avoid spillage. Carcass strength defines maximum tension and is calculated from conveyor length, lift height and capacity; insufficient strength causes stretching and tearing, excess adds unjustified cost. The top cover contacts material and wears, the bottom cover contacts rollers and pulleys; for abrasive material the top cover may be 2 to 3 times thicker than the bottom, and a correct ratio extends life without overcost. Splicing options are hot vulcanization, stronger and more durable but requiring stoppage and qualified personnel, or mechanical fasteners, faster to install but creating surface irregularity and weaker at high tension.

Conclusion

Belt selection balances wear resistance, strength and cost; a correctly matched belt pays back through long service life and minimal downtime.