Stacker-Reclaimer Product

Overview

A stacker-reclaimer is the machine that manages bulk-material stockyards at mines, ports and power stations. Stockpiles exist to decouple processes that run at different rhythms — trains arrive in batches, ships load in surges, a power station burns steadily — and the stacker-reclaimer is the interface: it builds piles from the incoming conveyor (stacking) and digs them back onto the outgoing conveyor (reclaiming). Combining both duties in one rail-mounted machine, rather than separate stackers and reclaimers, halves the yard machinery where simultaneous stacking and reclaiming on the same rail line is not required.

The machine is large by any standard: 500–2,000 t of steel travelling on yard rails, a Boom & Conveyor of 30–60 m slewing through ±110°, and throughputs from 1,500 to 10,000 t/h on coal and iron ore.

How it works

Stacking. Material arrives on the yard conveyor running between the rails. The Tripper Car — a travelling hump in the conveyor that moves with the machine — lifts the belt and discharges it through Transfer Chute onto the Boom Belt, which runs outward and drops material off the boom tip. By combining long travel, slew and luff, the machine builds piles in defined patterns (chevron, windrow, cone-shell); the pattern matters because layered stacking followed by full-face reclaiming blends out quality variations in the incoming material, and many yards are run deliberately as blending beds.

Reclaiming. The boom belt reverses. The Bucket Wheel at the boom tip — a cell-less wheel of 5–12 m diameter carrying 8–10 Buckets — rotates at 4–10 rpm while the Slew System sweeps the boom across the pile face. Each bucket scoops a sickle-shaped cut, lifts it over top centre and dumps it through the wheel's internal chute ring into the Discharge Chute and onto the inward-running boom belt, then across the machine onto the yard conveyor. The pile is taken in horizontal benches: the wheel slews across one terrace, the machine steps forward 0.3–0.8 m on its Long-Travel System, slews back, and after finishing a bench the Luffing System lowers the boom to the next one.

Reclaim rate control is a real control problem: the cut cross-section varies with slew angle (the wheel digs deeper into the face at the pile centre), so the Machine PLC modulates slew speed continuously — slower at the edges, faster in the middle — to hold the tonnage measured by the Belt Scale constant. The Torque Limiter in the Wheel Drive Unit protects the gear train when a bucket meets tramp steel or frozen material.

Structure and stability

The whole upper works — boom, machinery, Operator Cab — rotates on a Slew Bearing, a triple-row roller ring of 3–6 m diameter that carries the full overturning moment, driven by several Slew Drive Unit pinion units sharing load on the ring gear. The Counterweight Boom balances the bucket-wheel boom about the slew axis so the bearing sees moment, not gross imbalance. Below, the Portal Gantry gantry straddles the yard conveyor and rides on equalized Travel Bogies that spread wheel loads to values the yard rails can take.

Wind governs survival. An Anemometer alarms as wind rises; above the operating limit the machine luffs down, slews to its parking orientation and sets spring-applied Storm Rail Clamps that lock it to the rail head — unanchored yard machines have been blown along their rails and destroyed in storms. Luffing Cylinders carry counterbalance valves so a hose failure cannot drop the boom.

Automation

Stockyards are among the most automated heavy-machine environments in mining. Pile Laser Scanners map pile surfaces in 3D, the yard management system tracks every parcel of material by grade and position via the Travel Position Encoder and slew/luff sensors, and complete stack and reclaim jobs execute automatically with collision avoidance between machines. Operators increasingly supervise from a remote operations centre over the CCTV System feeds — at several large iron-ore ports the cab is occupied only for maintenance moves. Power follows the machine through the MV Cable Reel at 6.6–11 kV, feeding the VFD lineup in the Drive & MCC Room.

Wear and maintenance

Bucket teeth and lips, chute liners and the boom belt are the consumables; Idler Sets and Belt Protection Switches hardware are routine replacements. The slew bearing is the critical long-lead item — grease sampling through the Slew Lubrication system and periodic rocking-deflection measurements track raceway wear, because changing it means lifting the entire upper works.