Belt Width Selection Fundamentals
Belt width selection is determined by two constraints: the required material carrying capacity (tonnes per hour) and the maximum lump size of the material being conveyed. Both constraints must be satisfied —?the larger of the two resulting widths is the minimum required belt width.
Constraint 1: Capacity-Based Width
The capacity of a conveyor depends on the cross-sectional area of material on the belt, the belt speed, and the material bulk density. The standard formula is:
Q = 3600 × A × v × ρ × k
Where: Q = capacity (t/h), A = cross-section area (m²), v = belt speed (m/s), ρ = bulk density (t/m³), k = inclination factor (1.0 for horizontal, reduces for inclines)
The cross-sectional area A depends on belt width and trough angle. For a standard 35° trough angle:
| Belt Width | Cross-Section Area (35° trough) | Capacity at 2.5 m/s, ρ=1.6 t/m³ |
|---|---|---|
| 600mm | 0.038 m² | ~550 t/h |
| 800mm | 0.070 m² | ~1,000 t/h |
| 1,000mm | 0.110 m² | ~1,600 t/h |
| 1,200mm | 0.160 m² | ~2,300 t/h |
| 1,400mm | 0.220 m² | ~3,200 t/h |
| 1,600mm | 0.290 m² | ~4,200 t/h |
| 1,800mm | 0.370 m² | ~5,300 t/h |
| 2,000mm | 0.450 m² | ~6,500 t/h |
Constraint 2: Lump Size-Based Width
Large lumps of ore require adequate belt width to be carried safely without rolling off the edges. The rule of thumb is:
- For sorted (sized) material: Belt width —?3.3 × maximum lump size
- For unsorted (run-of-mine) material: Belt width —?2.5 × 90th percentile lump size
Example: ROM copper ore with maximum lump 300mm —?minimum belt width = 2.5 × 300 = 750mm —?select 800mm belt.
Speed Selection
Higher belt speed allows smaller belt width for the same capacity, but increases wear, noise, dust generation, and requires more careful loading zone design. Recommended maximum speeds:
| Material | Maximum Belt Speed |
|---|---|
| Fine coal, grain | 4.0—?.0 m/s |
| Crushed ore <50mm | 3.0—?.0 m/s |
| Crushed ore 50—?50mm | 2.5—?.5 m/s |
| ROM ore >150mm lump | 1.5—?.5 m/s |
| Fragile material | 1.5—?.0 m/s |
💡 Design Margin
Always add 20—?5% design margin to required capacity when selecting belt width. Mines rarely operate at exactly the design tonnage —?throughput typically increases over time as the operation ramps up. Selecting a belt that operates at 80% of its rated capacity gives headroom for increased throughput without system changes.
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