MINING
GOING FOR GOLD
Uzbekistan’s mining sector last year marked a major milestone with the commissioning of the country’s first 1,000m vertical skip shaft. The 6.5m wide skip shaft at the Zarmitan underground gold mine is designed to hoist up to 1.4 million tonnes of ore annually. Operated from a centralised control station and equipped with automated diagnostics and real-time monitoring systems, it is a step-change in capacity, efficiency and safety. Navoi Mining & Metallurgical Company (NMMC), the world’s fourth-largest gold
producer, operates the facility. “The skip shaft is a vertical mine shaft specifically designed for hoisting ore from underground workings to the surface,” says chief engineer Atabek Ravshanov. “At Zarmitan, ore from various underground levels is now gathered below ground at the 240m level, from which it is centrally hoisted to the surface.” This project includes two shafts: the skip shaft and the cage shaft. The skip shaft is equipped with two 20t ore bins designed exclusively for hoisting ore to the surface. The cage shaft facilitates personnel transport and equipment delivery to and from the surface across nine underground levels, at roughly 60m intervals, down to 480m. Both shafts are fitted with advanced information and communication systems. Operations are controlled from a centralised operator station, enabling real-time monitoring of production processes and precise tracking of hoisting operations through automated data analytics. The system is also designed to detect and prevent operational anomalies via early warning alarms and diagnostic protocols, ensuring a high level of safety and reliability. The new shaft significantly increases ore hoisting capacity, reduces operating costs and has already resulted in the creation of 90 new jobs. Once in full operation, the shaft will deliver approximately 1.4Mt of ore annually to Processing Plant No. 4. The estimated annual economic impact from the project is about $1.5m. Ukrainian companies were responsible for the project: NKMZ supplied the hoist system and the winder; Preobrazovatel-Complex supplied the control system.
manager for ABB. “Once you start getting beyond 3.3km, the weight of the rope itself that is suspended in the shaft starts to become a significant proportion of the payload.” If rope technology is developed to weigh less, with hybrid or composite or synthetic material, then more of these deeper orebodies can be exploited. “There is no question the rope is the limiting factor.” A recent paper ‘Composite Steel Wire Ropes for Mine Hoisting Applications’ by Rebel and others highlights the potential of such lighter hoisting ropes in extraction. “A 20% reduction in rope mass per metre for a typical 48mm hoisting rope increases the skip’s capacity by about 30% at a suspended rope length of 3,000m,” they say. “Such gains in shaft output, without any significant changes to the shaft or winder design, can of course have major implications for the feasibility of future deep mine projects. The technical challenge for rope manufacturers is how to get rid of 20 to 30% of the rope mass while keeping the breaking strength and modulus of elasticity of the whole rope constant,” says the report. Mine rope specialists CASAR are currently developing steel wire rope constructions where the steel inner core has been replaced with high strength, high modulus but lighter synthetic fibres. The reduction in rope mass per unit length, and an increase in rope breaking strength, will give greater hoist skip capacity and hence increase mine shaft output.
Going large
Capacities must become larger. This, too, ABB can demonstrate, but this time in Canada. They are delivering a hoist with the largest production capacity in the world. The client is the BHP Jansen Potash Project in Saskatchewan. Potash, used in fertiliser, has been in the news recently as one of the key products affected by the Strait of Hormuz closure and is crucial for both more sustainable farming practices and food security. Demand, as we have said, has been rising and Canada is a key producer. The hoist will transport payloads of 75 metric tonnes, which is a world record. The shafts are a kilometre deep. Its six ropes will be able to lift the loads at a maximum speed of 18.3m/s; dual 7,700kW motors will power it. Three friction hoists are being delivered to the
project, as well as an electrical system for a fourth service hoist. The service shaft and production shaft have both been sunk in preparation for the hoisting systems. ABB has delivered two hoists to the service shaft, including the cage, as well as the hydraulic braking system and the electrical controls and powertrain for a temporary cage hoist being commissioned in the production shaft, which will be in operation for two years while the higher capacity Kuyper (friction) production hoist is prepared. The latter will then be installed and is expected to be up and running for production use by 2027. The project represents a breakthrough in enhanced productivity. It too will have one of the highest levels of safety available, with fully SIL 3 certified ABB Ability Safety Plus for hoists. Installation of the initial two hoists is currently in
progress; the further two hoisting systems are being prepared for installation and commission between 2026 and 2027.
34 | May/June 2026 |
www.hoistmagazine.com
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