For the owners of Australia’s largest tin mine – the fabled Renison Mine in northwest Tasmania – it had long been a strategic priority to replace an electrical system that was older than any employee at the site. But doing so without losing a single full day of production proved to be an even more critical business decision.
During the 12 months that it took to completely refurbish Bluestone Mines’ switchyard, the price of raw tin skyrocketed more than 190% on global markets – demonstrating the vital importance of a contractor who can safely and swiftly replace electrical infrastructure while it’s still in operation.
The switchyard upgrade included the installation of two 7.5 MVA transformers and a 5 MVA transformer, main breaker and metering systems, and a brand new switch/control room, plus the upgrading of all electrical protection schemes to digital relays.
The construction phase of the project involved the restringing of a 44,000-volt copper busbar over three 12-hour shifts in November, enabling the underground section of the mine to continue production at night during a particularly lucrative period. The job involved installing 106 insulators airfreighted from Shanghai and reenergising the system at the end of each shift – so that vital dewatering and ventilation equipment could continue running underground.
“When the power’s shut down at the mine, water immediately begins to seep into the lower sections and puts equipment at risk, so the Renison Mine were putting a great deal of faith in us,” says Frontline Electrical Project Manager Jason Bryan .
“The requirement for a nightly power supply that provides life support to operations meant these critical cutovers had to be strategically planned, down to the smallest nut and bolt.”
Timed to perfection
The intensive construction was completed on time and on budget in late November, by which time the price of tin had risen to more than US$39,500 a ton – having stood at US$13,500 a tonne back in March.
“When we were doing the definition phase of the job in late 2020, the price of tin started rising – and it kept on rising,” says Frontline’s HV Construction Manager, James Carney. “Of course, the mine’s owners wanted to keep working throughout – they needed to make hay while the sun was shining!
“When we were putting in the new transformers, we had to bypass each in turn, so that the electrical supply wouldn’t be disrupted. The last job is the installation and commissioning of the 60-ton one-piece switchroom delivered from Adelaide – again, all the while ensuring continuous production.
“In spite of all the work we’ve been doing, the mine has managed to significantly increase its production over the past year. I’m really proud of this Frontline team, which is the best that I’ve worked with for a very long time.”
As well as replacing every piece of the switchyard – from wires and gantries to insulators and transformers – the project entailed strict processes for isolating, de-energising and re-energising the yard, as well as close liaison with TasNetworks and the mine’s switching operators to control power fluctuations in the area.
“Building a greenfields switchyard from scratch is so much easier, as you’re putting everything in at the same time on a blank canvas,” explains Jason. “This job involved replacing old equipment one piece at a time in a really strategic manner. There were constant risks of overloading the system or damaging high-value components during the installation periods.
“There are also no replacements for a lot of these parts, which had to be imported from Brazil, India and China. You would have had to wait for another six months if you damaged anything!”
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