Overview
This project involved technical retrofitting of the hoisting system in the main shaft of a coal mine operated by a mining group. The original equipment was a JKM multi-rope friction hoist; prolonged full-load operation had resulted in problems such as cracking of the friction wheels and aging of the braking system. The retrofitting objectives included enhancing hoisting safety, improving operating efficiency, and optimizing energy consumption. The project was launched in 2007 over a period of 45 days and achieved stable operation after commissioning.
Process Engineering
Core technology: Utilizes multi-rope friction-type lifting technology, complemented by a high-voltage variable-frequency speed control system, enabling four-quadrant operation (seamless switching between electric drive and regenerative braking).
Control method: dual-PLC redundant control combined with a vector control algorithm, ensuring precise regulation of speed and torque.
Braking system: The hydraulic disc brakes support two-stage braking, with a safety response time ≤ 0.3 seconds.
Configuration
| device name | ts | key parameter |
| Hoist main body | JKM2.8*4 | Friction wheel diameter: 2.8 m; 4-rope configuration |
| any power-generating or power-driven machine | YTS series dedicated variable-frequency motor | Power: 800 kW; Voltage: 10 kV |
| Variable-frequency system | GBP-NT high-voltage frequency converter | Quadrant IV energy feedback; overload capacity: 150%/120s |
| Control System | Dual FX3U Series PLC + Host Computer Monitoring | Integrates 36 security protection functions |
| brake apparatus | Disc brake (TP6.3T) | Gate clearance: 1 mm; contact area: ≥60% |
Technical Feature
Intelligent O&M: The remote diagnostic system monitors equipment status in real time via Ethernet and supports fault prediction.
Structural optimization: The main shaft is made of 45MnMo alloy steel; the brake disc thickness has been increased to 42 mm, extending service life by 30%.
Energy efficiency design: the power factor of the high-voltage frequency converter shall be ≥0.95, and the harmonic distortion rate shall comply with the IEEE 519 standard.
Capacity Expansion
The lifting speed has been optimized from 2.5 m/s before the retrofit to 3.7 m/s; the single-lift capacity is 26 tonnes, and the hourly processing capacity has been increased to 280 tonnes (calculated based on 10 cycles per hour).
