Digging deeper: Tanami Gold Mine gets a lift

Shaft mining is the way forward for gold mines going below 500 meters. ABB electric hoists to move people and ore safely, efficiently and cleanly.

It doesn’t take much to get a small gold mine going: “A multitasking tractor-loader-backhoe, a crusher and wash plant, would do it,” says Paul Barclay, Sales Manager for Process Industries at ABB. Fast forward to Newmont’s Tanami mature mining operation in the remote Northern Territory, a constantly evolving operation that is currently undergoing its second major expansion project of the decade.

Part of the project will see two digitally enabled, ultra-safe ABB electric hoist systems providing access to the rich Auron ore body more than two kilometres below the surface, which was discovered below the currently mined Callie body, in 2008.

The $24 million hoist contract includes design, supply, engineering, installation supervision and commissioning of all associated electrical and mechanical equipment. Ultimately, this end-to-end solution will contribute to an increase in gold production of between 150,000 oz and 200,000 oz per year on average for the first five years from the expected time of commissioning in 2023. And extraction from Auron is anticipated to extend Newmont’s Tanami mine life, from the previous expectation of 2027, out to 2040.

“The Tanami expansion project, TE2, includes construction of a shaft that can reach 1,460 meters below the surface to enable recovery of ore at a depth; this provides a viable solution to extend the mine,” says Neil Steyn, Regional Project Director at Newmont, one of the world’s most advanced miners of gold.

Since acquiring the Tanami assets in 2002, Newmont has modernised their operation, including ensuring reliable electricity to the extremely remote location with the construction of two gas-fuelled power stations supplied by a 440-kilometre gas pipeline from the existing Amadeus Pipeline in central Australia to the Newmont Granites site. Granites, which was mined from 1988 to 2003, is now used for processing the ore drawn from Dead Bullock Soak (DBS), 42km away, where the Callie, Federation and Auron orebodies are situated.

Over previous decades, the operations of each of the Tanami mines has progressed from open-cut to underground operations, but the method of trucking ore from underground at Callie now presents logistical, ventilation and cooling challenges to expansion.

Ore extraction, going up!

The ABB-designed solution of a friction hoist to transport ore to the surface, and a double-drum personnel-riding hoist, will be supported by additional investment in processing. Together, they are “expected to increase production to 3.5 million tonnes per year,” says Steyn. That’s tonnes of ore, which will be partially crushed underground to enable more efficient (less empty space between ore chunks) transport of rock to the surface. The hoist will increase orebody-to-surface capacity by almost a million tonnes per annum over the current 2.6 million tonnes carried by truck.

This transition to digital-drive electric haulage represents the next technological leap for Newmont at Tanami. The mine will be the first in Australia to operate hoists fully enabled with Safety Integrity Level 3 (SIL3) Safety Hoist monitor and Brake System from the time of installation. The SIL3 rating is based on the value of risk reduction associated with a Safety Instrumented Function (SIF) protecting against a specific hazardous event, or how the risk has to be reduced to reach an acceptable level.

“You can imagine: you’re lifting 30 tonnes out of a hole that’s more than a kilometre deep,” explains Barclay. He says, “You have to do everything you can to keep control of the winder as it runs through its cycles. If the control system fails or a motor fails, or something really untoward causes a problem, you must have at least three Safety Instrument Functions (SIFs) that detect anomalies and protect the hoist from out-of-control speed, and safely stop the hoist.”

Safety of mine infrastructure is a constant field of R&D, and ABB is ahead of the pack in having developed and verified its new SIL3 Safety Hoist monitor and Brake System, which is set to become the norm on Australian sites.

Smooth operations through cloud-based monitoring

Remote monitoring of the commissioned hoists, alongside an optimised onsite spares holding and replacement parts will ensure the second critical requirement of this investment: to keep the ore coming.

ABB Hoist Monitor, running on the integrated ABB Ability^TM digital platform, provides 24/7 remote analysis of system condition and performance of the company’s hoists, enabling fault prediction and preventive maintenance.

Barclay says ABB Ability Remote service and support are critical in the current environment. Potential restricted site access due to COVID-19 is one thing, but the remoteness of DBS mineral lease in the Tanami Desert, some 560 km northwest of Alice Springs and 940 km southwest of Darwin, means physical response by a systems engineer to problems on-site is limited by the once-daily flights to Tanami Operation from Perth, which could translate into tens of thousands of tonnes of production lost.

ABB Ability Performance Optimization for Hoist will assist  Newmont with the highest possible levels of system availability, performance and productivity monitoring as the company extends its reach into new realms of efficiency and the earth’s resource-full crust.