MINE SHOCK: Mt Morgan project poised to restart

MOUNT Morgan's long abandoned mine could bustle once more, thanks to technological advances which make reprocessing gold tailings at the site financially viable.

In addition to bringing economic activity and employment back to the township, the technology that would be brought to bear has the ability to help clean up the problematic environmental contamination at the mine site.

Buried in the 2020 Resources and Energy Major Projects report which was handed down this week by the Australian Government's Department of Industry, Science, Energy and Resources, were brief mentions of the potentially game-changing project.

In a list of resources and energy sector projects at the feasibility stage were 17 gold projects, with the Mount Morgan project among five which were recognised as having the potential to progress to "committed" in the near term, provided there were supportive market conditions.

The report said Heritage Minerals' $60 million Mount Morgan project had "recently completed a positive definitive feasibility study".

The tailings at Mount Morgan could be reprocessed in a financially viable manner thanks to the development of RECYN technology.
The tailings at Mount Morgan could be reprocessed in a financially viable manner thanks to the development of RECYN technology.

"Heritage Minerals' $60 million Mount Morgan project in Queensland is expected to be reactivated at the end of 2021, after production ceased in 1990," the report said.

"The past year has seen a surge in reactivated gold mines, as higher prices draw previously closed operations out for development.

"If all gold projects were realised over the time frame of this report, Australia's gold production would increase by about one third."

The news of the mine's potential reopening will be a welcome tonic for the bitter disappointment the community suffered after Carbine Resources' four-year bid to reopen the mine to reprocess its tailings collapsed in 2018 after determining the project was not financially viable.

Heritage Minerals Corporate Secretary Peter Mellor told International Mining that they were the sixth company to have a shot at reprocessing the tailings, with none of the companies before them getting past the feasibility study stage into financing.

He said they were all unsuccessful primarily because of the presence of nuisance copper and the high cyanide consumption required to remove it.

What sets Heritage Minerals' plan apart is its partnership with GreenGold Engineering - its mineral project development and production partner.

After gaining rights to the project from Norton Gold Fields following Carbine's exit, Heritage appointed GreenGold to carry out a definitive feasibility study.

GreenGold was the creator of the RECYN technology to capture minerals that were lost in the tailings - technology the company has successfully demonstrated at two mine sites.

Cyanide is established in the gold mining industry as the choice of solvent for gold and silver recovery from ores.

GreenGold described on its website how its technology used an "innovative resin-bead absorbent which reduces cyanide consumption by 50 per cent, capturing free cyanide from the plant tailings and recycling it back into the leach circuit while recovering metal complexes and making them available for sale".

"In the process, RECYN detoxifies the tailings stream and guarantees 100 per cent - compliant clean water discharge," GreenGold said.

"RECYN is efficient, economical and environmentally friendly. It is the only cost-saving innovation of its kind that is generating results today on an industrial scale."

The company could use the technology to detoxify the tailings stream and clean up the water discharge at Mount Morgan.

It would provide an invaluable to support for the Department of Natural Resources and Mines who currently treat the water from the open pit and tailings deposits before it was released into the local creek due to the low pH levels caused by the acid-forming pyrite.

"We wanted to get the economic, environmental and social aspects ticked off first before laying out any longer-term plans," Mr Mellor said.

"Our process plant will use this water, treat it and send it out as clean water down the creek.

"We have come up with a really neat environmental rehabilitation scenario where we fill the existing open pit up, and cap it all off nicely so the surface water cannot penetrate."


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Heritage Minerals could reopen the Mount Morgan mine at the end of 2021.
Heritage Minerals could reopen the Mount Morgan mine at the end of 2021.

Discussing plans for the Mount Morgan mine on its website, Heritage Minerals said the project's fundamentals were completely changed from previous concepts to provide an economically feasible project.

"The focus was placed on achieving an economic gold project without the distraction of by-products," Heritage Minerals said.

"The production rate was doubled and the capital cost reduced by a significant simplification of the flowsheet.

"There were many other core changes incorporated into the revised design to achieve the elegant result that turned the project around.

"The environmental solution is much improved, providing a more substantial clean-up of the total site."

According to Mr Mellor, if all goes to plan for the project, operations - a simplified earthmoving and processing method - could begin in 2022.

A spokesperson for Heritage Minerals was contacted for comment on the project but didn't respond before deadline.


The benefits of the RECYN process

• Cyanide is economically recycled.

• Carbon-in-leach plant tailings are economically detoxified.

• Metal values such as copper are economically recovered.

• Gold and silver recoveries can be increased.

• It can add reserve value and extend mine life.

• Perhaps the most significant benefit is changing the negative perception of cyanide.


Background on the Mount Morgan mine

Mount Morgan is located in Queensland, Australia and was the largest gold mine in the world at its peak in the early 1900s.

Over its lifespan, the mine yielded about 262 metric tons of gold, 37 metric tons of silver and 387,000 metric tons of copper.

Originally an open-cut gold mine at the top of the mountain, Mount Morgan converted to an underground copper and gold mine.

In 1935 it transitioned back to open-cut and continued until the mine closed in 1980.

As with many older mining projects, the legacy of Mt. Morgan is a large hole in the ground, waste and tailings stockpiles that produce contaminated water.

Peko Wallsend Limited ran a tailings treatment operation from 1982 until 1991, recovering gold from 27Mt of tailings.

Mount Morgan pioneered many metallurgical processes to cope with the unique properties of the ore.

From chlorine leaching in the early days to various smelting furnace techniques for the refractory ore; the Mount Morgan tailings stockpile has a rich and varied history.

At different stages in the life of the mine, copper was either a bonus or a nuisance. When copper grades were high, copper was a financial benefit.

When the copper grade was low, the metal increased operating cost for the gold recovery.

The RECYN technology applied by GreenGold overcomes the copper issue.