Conveyors & Hoists

Continuous and vertical transport: belt conveyor capacity and power, in-pit crushing and conveying (IPCC), overland conveyors, hoisting ropes and factors of safety, and when conveyors beat trucks.

Conveyors move ore continuously with electric power at a fraction of truck cost per tonne-km, especially for long distances and steep lifts. Hoists lift ore from deep underground mines. Both are key technologies for low-carbon mining.

An analogy

A conveyor is a moving river of rock — instead of many small boats (trucks), one continuous stream does the work.

Conveyor components

Belt (fabric or steel-cord), idlers (troughed at 20–45°), pulleys and drives, take-up for tension, transfer chutes, belt cleaners and scrapers. Maximum incline ≈ 15–18° for conventional belts; steeper with sidewall or pipe conveyors.

IPCC

In-pit crushers (fixed, semi-mobile or fully mobile) break ore/waste to conveyable size (≤ 300 mm) and feed conveyors up the pit wall — cutting truck fleets, fuel and emissions, at the cost of flexibility.

Hoisting

Skips hoist ore in shafts; rope safety factors are statutory and depth-dependent (rope self-weight grows with depth). Rope inspection (NDT) and brake testing are critical.

Design standards

CEMA and ISO 5048/DIN 22101 methods compute belt tensions, power and belt rating. Belt condition monitoring, fire detection and guarding prevent the frequent conveyor entanglement injuries.

Formulas

• Conveyor capacity: Q = 3.6 A v ρ_l (t/h)
• Lift power: P_lift = (Q/3.6) × g × H (W, Q in t/h)
• Drive power: P ≈ (P_lift + friction) / η_drive
• Rope factor of safety: FoS = breaking strength / (payload + conveyance + rope) weight

Worked example: Belt load area

Given: 3000 t/h, belt speed 5 m/s; ρ_l 1.6 t/m³

Find: Required load area.

• A = 3000/(3.6 × 5 × 1.6) = 0.104 m²

Answer: ≈ 0.10 m² (≈ 1400–1600 mm troughed belt)

Worked example: Lift power

Given: 3000 t/h, lift 150 m; +20 % friction, 90 % drive

Find: Power.

• P_lift = 833 × 9.81 × 150 = 1.23 MW
• P = 1.23 × 1.2/0.9 = 1.64 MW

Answer: ≈ 1.6 MW

Common mistakes

• Wrong: Ignoring conveyor guarding. — Right: Guard pinch points; isolate before maintenance.
• Wrong: Assuming conveyors suit every pit. — Right: Frequent moves and multiple faces favour trucks.

Applications

• IPCC systems: Large copper and iron-ore pits.
• Overland conveyors: Tens of km to ports or plants.
• Shaft hoisting: Deep underground mines.

Key takeaways

• Q = 3.6Avρ.
• Power ≈ lift + friction.
• IPCC cuts trucks and emissions.
• Rope FoS falls with depth.

Going further

• Belt tension design: DIN 22101 / CEMA calculations.
• High-angle conveyors: Sandwich belts for steep lifts.
• Rope NDT: Magnetic flux inspection of hoist ropes.