Shaft Hoisting System for a 600 m Fluorite Mine: Direct PMSM Drive Replaces Gearbox and HV

The mine hoist is the link between the underground workings and the surface: ore, waste rock, miners, materials and equipment all travel on it. When this fluorite operation planned a 600 m vertical shaft with a target output of 600,000 t per year, the incline hoisting that suits shallower deposits was no longer an option — vertical shafts need a winder that holds torque at very low rope speed.

The conventional answers were both unattractive. A 380 V induction motor with a gearbox and drum adds a reducer that needs oil changes and periodic overhaul, and its accuracy depends on gear backlash. A 10 kV drive with a 10 kV motor and drum avoids the gearbox but multiplies the cost of the switchgear, the motor and the cable.

Yolico proposed a third route: a 630 kW outer-rotor permanent-magnet synchronous motor built into a multi-rope friction winder, driven directly at 380 V. The rotor runs at 50.3 rpm at a rated current of 1007 A, so the drive was specified at 1250 A — the YDS8800 T4 WN-S fitted with a SinCos encoder card for the position feedback a hoist needs before it is allowed to move.

Commissioning ran from the safe end inwards. With the conveyances empty, the encoder offset was learned and the cage run dry. Rope was then wound onto the drum and the parameters trimmed under load. The records captured speed command, actual speed, torque and current together at 1.5 rpm and 12.5 rpm, loaded and empty, so the winder's behaviour at crawling speed could be compared against the design duty rather than assumed.

The result satisfied both the mechanical and the commercial case. Removing the gearbox removes its maintenance and its backlash; remains the same 380 V supply the rest of the plant already runs on, so no 10 kV switchgear, motor or cable had to be purchased. During the trial the mine pushed the load to 110 % of rated and the winder held 0.5 rpm without complaint — a useful margin for a machine whose job is to bring people back up.