Raising the viability of a project badged with important heritage status has been a feat for Heritage Minerals. The company tells Australian Mining how it will become the first to produce gold at Mount Morgan in 30 years.
Several companies have come in intending to recover what gold is left at the mothballed Mount Morgan mine site in Central Queensland over the years.
Once the world’s largest gold mine, Mount Morgan produced around a century’s worth of commodities, including copper and silver.
Mount Morgan has yielded around 262 tonnes of gold, 37 tonnes of silver, and 387,000 tonnes of copper over its lifespan.
Today, the abandoned mine has left engineers scratching their heads for how to sustainably recover gold and copper from the tailings stockpiles.
The presence of high levels of cyanide soluble copper in the tailings increased the operating costs so high that any conventional gold recovery process became uneconomical.
The cost issue is exacerbated with acidic water from the old open-cut mine, which requires a great deal of lime so it can be processed and used.
Heritage Minerals, the fifth company in the last 30 years that has tried to resume production at Mount Morgan, is on track to be successful.
Heritage has completed a definitive feasibility study (DFS) for processing tailings at Mount Morgan using GreenGold Technology (GGT) expertise.
Following the DFS, the Mount Morgan project has shown to be bankable with a capital payback period of just one year.
Heritage anticipates that Mount Morgan will produce 50,000 ounces of gold a year over a six-year lifespan, with the potential for life extensions.
“The specific technology from GreenGold that we’re applying, called ReCYN, allows for the economic recycling of cyanide and recovery of the copper, along with its associated cyanide,” Heritage chief executive Malcolm Roy Paterson tells Australian Mining.
“The ReCYN Process uses a specific resin that absorbs the active cyanide and metal cyanide complexes so we can recycle the cyanide and recover the metal complexes.”
Paterson says the ReCYN technology has turned around five beleaguered projects internationally, including one in Western Australia and now the Mount Morgan project.
“It’s the main contributor to getting the project across the line,” he says.
Partnering with GGT has provided Heritage not only with the benefit of exclusive technology, but also with an innovative approach to project development that reduces capital and operating costs.
The GGT company carries a broad range of talent composed of in-house engineers, metallurgists, process engineers, design engineers, project executioners and procurement professionals.
“We have a full spectrum of project development capabilities, from exploration to operations, but at the same time we operate in a very narrow specialist field mainly focussing on gold and copper,” Paterson says.
“We kept ourselves to a small team of specialists who take an integrated approach to problem-solving, and that gives you a really powerful group.
“We don’t need to go outside to a myriad of consultants when doing feasibility studies, which gives us tremendous benefits in terms of communication and collaboration.”
Heritage intends to start construction at the Mount Morgan site next year, targeting commercial production by the end of 2021 and employing about 70 people in a region that is plagued with high unemployment rates.
Given the immense historical interest Mount Morgan carries, Heritage recognises the significance of the mine site for regional tourism opportunities.
The Mount Morgan site includes fireclay caverns containing dinosaur footprints in the sandstone roof.
Paterson says the Rockhampton Regional Council is interested in reviving the location as a tourist destination.
“The caverns were excavated between 1906 and 1927 for clay to supply local brick making, including the bricks that were used to build Mount Morgan’s administration building in 1905, which is still in use today,” he says.
“We’ll restrict our operation to a small area so we can avoid crossing paths with those areas that might be future tourist spots.”
To Paterson, Mount Morgan is fascinating not only because of its rich history and prevailing technical issues, but also because of its environmental and heritage challenges.
“Getting the tourism back up and running will help improve the social situation of the communities that are suffering from one of the highest unemployment rates in Australia, and environmental clean up of the historical tailings will make a significant contribution to improving water quality in the downstream catchment,” he concludes.
This article also appears in the October issue of Australian Mining.