At a glance
Choosing a coal conveyor system means matching belt width, belt speed, lift profile, and drive arrangement to the required capacity, material properties, and operating environment. The right answer is the system with the lowest total cost of ownership over its expected service life, not just the lowest capital cost.
Step 1: Define capacity and material
Start with required throughput (tph), expected variability, peak rates, and material properties (bulk density, lump size, moisture, abrasiveness). These drive every other decision. For coal, typical bulk density is 0.75–0.95 t/m³; lump size and moisture vary widely with source and processing stage.
Step 2: Select belt width and speed
Belt width must accommodate the largest expected lump (a guideline is 3x the largest lump dimension). Within a given width, capacity scales with belt speed. Higher speeds increase capacity per dollar of conveyor structure but raise belt wear, idler load, and dust generation. Coal conveyors typically run at 2.5–4.0 m/s; long overland conveyors run faster (up to 5+ m/s).
Step 3: Determine lift profile
Belt inclination is limited by material angle of repose. For coal, typical maximum is 18° on flat-troughed belt. Higher lifts use chevron belts, sidewall belts, or pipe conveyors. Long horizontal conveyors are typically less expensive per ton-kilometer than highly inclined ones.
Step 4: Choose belt construction
Steel cord belts are used for long-center, high-tension applications. Fabric belts are used for shorter, lower-tension conveyors. Cover compound is selected for material abrasiveness and operating environment; underground coal mine service requires fire-resistant cover grades.
Step 5: Drive and take-up
Single-head drives are simplest. Multiple drives (head and tail, or head-only with multiple motors) reduce belt tension. Soft-start systems (fluid couplings or VFDs) reduce starting torque. Take-up choice (gravity, screw, hydraulic) depends on conveyor length and required tension control.
Step 6: Integrate auxiliaries
Conveyor selection is not complete without belt cleaners, idler types, dust control, protection devices, and transfer station chute design. These are 'small' items in capital terms but dominate operational performance and maintenance cost.
Step 7: Total cost of ownership
Compare options on TCO over expected life: capital, energy, belt replacement, idler replacement, transfer point maintenance, downtime, and end-of-life decommissioning. Many cheap-capital options have higher TCO than their more expensive alternatives.