Tag Archives: Mount Morgan

Heritage Minerals smashes Dando Terrier percussive drilling depth record

The Heritage Minerals team, led by Drilling Manager, Shane Charlton, has been achieving depths of 46 m with high-quality 86 mm samples using Dando Drilling’s Terrier percussive drill rig, the drilling manufacturer says.

The depth is a record for the Terrier rig, according to Dando.

Heritage Minerals is currently working on the historied Mount Morgan mine in Queensland, Australia. One of Australia’s oldest mines, Mount Morgan was active from 1882 through to the 1980s. In the process, tens of millions of tonnes of tailings were generated.

Today, these tailings present both a problem and an opportunity; a problem because they were subject to old, polluting technologies for processing gold, but an opportunity because they still contain reserves of gold, copper and other minerals.

Heritage Minerals is employing innovative processing technologies such as ReCYN, developed by partner GreenGold Engineering, to clean pollutants from the tailings and returning them to safe land.

It was this technology and the tailings recovery aim IM recently focused on for an in-depth article on Mount Morgan.

Heritage chose a Dando Terrier rig to sample the tailings at Mount Morgan for several reasons, Dando said.

“Foremost, the unconsolidated geology of tailing fines is very hard to sample with conventional rotary equipment,” it said. “The Terrier’s Duplex Sampling System, which is driven into the ground by a 64 kg anvil and simultaneously cases-off and samples, provides excellent recovery in this type of unconsolidated geology for metallurgical and in-situ density measurements.”

Charlton proved and refined the drilling method he used in the mineral sands of Kalimantan, Indonesia, where he sampled alluvials to over 20 m for lab analysis, Dando says. This is an impressive feat for a rig that has a large user base for geotechnical sampling, standard penetration testing and dynamic probe testing, most often at depths of less than 15 m.

More than doubling this to 45 m was no easy task, Charlton explained: “At depth, it took almost 10 minutes to trip the drive rods and retrieve the sample, but the quality of the sample and the economies in terms of cost per metre offset the sometimes slow drilling.”

Heritage has recently purchased a second Terrier rig from a Dando customer in Australia and Charlton has made some modifications to the design to facilitate drilling beyond the original specifications of the rig.

“We’ve fitted a permanent casing extractor to help pull sample tubes and casing if they get stuck, as well as modifications to assist with tripping rods more quickly,” he said.

To achieve these depths, the team are using a reaming method whereby they sample using an 86 mm windowless sampler tube, and then ream out using a larger 116 mm tube before returning to the 86 mm sampler to continue. This reduces frictional forces along the side of the borehole and abrasive tailing materials, according to Dando.

The percussive hammer system allows sampling without flush, minimising the need for cumbersome mud tanks or air compressors while preventing contamination of the sample or the environment, it added.

Heritage eyes up Mount Morgan riches, rehabilitation

A partnership between GreenGold Engineering and Heritage Minerals Pty Ltd has plans to return the Mount Morgan gold mine in Queensland, Australia, to some of its former glory by creating a mean and green way to extract gold from its ample tailings deposits.

The cooperation allows Heritage Minerals to develop the project in a proactive program to maximise the best chance of project success, the company says. Heritage admits it has a big task on its hands, facing doubters that have witnessed a string of false starts at Mount Morgan.

The story behind Mount Morgan dates to 1882 when a syndicate was created to open a gold mine at Ironstone Mountain, 39 km south of Rockhampton.

Ironstone Mountain, later renamed Mount Morgan, was originally operated as an open-pit gold mine at the top of the mountain, before being converted to an underground copper and gold mine.

In 1935, it transitioned back to an open-pit operation and continued until the mine closed in 1980. After this, Peko Wallsend Ltd ran a tailings treatment operation from 1982 until 1991, recovering gold from 27 Mt of tailings.

Mount Morgan pioneered many metallurgical processes to cope with the unique properties of the ore over this time. From chlorine leaching in the early days to various flotation and smelting furnace techniques for the copper/gold ore, the Mount Morgan tailings stockpiles have a rich and varied history.

At different stages over 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 the operating cost associated with gold recovery.

This more than century of mining and processing came with consequences.

The pyrite remaining in the mine and tailings dumps is acid-forming and has generated a significant environmental legacy which remains today. This legacy has become the responsibility of the State of Queensland (1993) and is managed by the Department of Natural Resources and Mining’s (DNRM) Abandoned Mines Division.

Despite these environmental liabilities, five companies have come back to Mount Morgan since Peko Wallsend stopped operations in the early-1990s, encouraged by higher yellow metal prices and improved processing options for the refractory ore.

“We’re the sixth company to have a shot at reprocessing the tailings, with none of the companies before us getting past the feasibility study stage into financing,” Peter Mellor, Corporate Secretary at Heritage Minerals, told IM.

All of them were unsuccessful primarily because of the presence of nuisance copper and the high cyanide consumption that comes with removing this, according to Mellor.

The most recent company to try its luck at Mount Morgan is a case in point.

ASX-listed Carbine Resources developed a process flowsheet to remove part of the troublesome copper by acid leaching the tailings and producing copper sulphate. Additional revenue from the production of pyrite concentrate supplemented gold sales.

It was the production of premium quality (50% sulphur) unroasted iron pyrite concentrate that enabled the commencement of the reduction of acid-forming material at Mount Morgan, Carbine said.

Despite coming up with a 1.1 Mt/y blueprint that, in the expanded case, could operate for 20 years and produce 23,000 oz/y of gold, 2,700 t/y of copper sulphate and 200,000 t/y of pyrite concentrate, the plan ultimately fell down on the projected economic returns, negatively impacted by excessive royalty liabilities.

A February 2018 update came with a revised operating model at Mount Morgan showing all-in sustaining costs (AISC) of A$862/oz ($621/oz), A$313/oz higher than the company’s December 2016 feasibility study.

“The increase is due primarily to higher cyanide consumption and lower by-products credits due to a lower pyrite price and the loss of copper sulphate premium associated with a change in the copper products produced,” Carbine explained.

Fresh approach

To be fair to Mellor and the Heritage team, they are not looking to repackage the same project blueprint in a markedly better gold price environment as other companies have been known to attempt. Instead, they are setting up the project and the town of Mount Morgan for a brighter and sustainable future.

After gaining rights to the project from Norton Gold Fields following Carbine’s exit, one of the first things Heritage did was appoint GreenGold to carry out the definitive feasibility study.

Equipped with its ReCYN resin-based technology that has been shown on other projects to reduce cyanide consumption by up to 50% through capturing free cyanide from plant tailings and recycling it back into the leach circuit, the selection was an obvious choice.

The company could potentially detoxify the tailings stream and clean up the water discharge at Mount Morgan. This would be a boon for the DNRM, which currently treats the water from the open pit and tailings deposits before being released into the local creek due to the low pH levels caused by the acid-forming pyrite.

“Our process plant will use this water, treat it and send it out as clean water down the creek,” Mellor explained.

This is one of several changes the company is implementing to make the project viable.

“For example, Carbine were previously looking to float off the nuisance copper at the start, which came with the associated capital costs of building a flotation plant,” Mellor said. “Yet, the copper really represented a low amount of revenue (2,700 t of copper sulphate in the studies) overall.”

The ReCYN resin plant can deal with the higher cyanide consumption needed to treat the copper at the back end of the flowsheet. This will allow the company to focus on the gold – which represents 90% of revenue – that can be processed by a technically-simple carbon in leach plant.

Malcolm Patterson, MD of Heritage Minerals, and Peter Papa, Technical Director of Heritage Minerals, observe the task ahead at Mount Morgan

The open pit is partially filled with previously processed tailings, with Mellor saying the reprocessing of 10 Mt of tailings (averaging 1.1 g/ Au) can help complete the rehabilitation process.

“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,” he said.

Set to build a 2 Mt/y plant to re-process this material, Heritage is only looking five years out from first production, although there is potential for this processing quantity to be doubled.

Even with this near-term gaze, the definitive feasibility study (DFS) anticipates a one-year payback and an upfront capital expenditure bill of A$74 million (compared with Carbine’s last A$96 million estimate).

“There is more potential than this,” Mellor says of the feasibility study, highlighting several areas of interest within proximity of the existing open pit. “Yet, we wanted to get the economic, environmental and social aspects ticked off first before laying out any longer-term plans.”

The company has been very thorough in coming up with this five-year plan.

Already blessed with an extensive JORC resource database from previous Mount Morgan tailings reprocessing protagonists, the company continued to drill for tonnage and bulk density definition of the tailings resource; the latter with a Dando percussion drill rig capable of punching 1 m cores down to 30 m depth.

With a board decision on the DFS expected before the end of the year, Heritage could soon enter the financing stage, followed (hopefully) by construction.

If all goes to plan, operations – a simplified earthmoving and processing method – could begin in 2022.

“Mount Morgan is definitely not the easiest site, but it is the most prestigious in terms of history and challenges,” Mellor says.

Heritage and GreenGold will soon be judged by the financing community on whether they are up to such a challenge.

GlassTerra IoT LiDAR monitoring solution being trialled at Mount Morgan mine

Queensland, Australia-based technology startup GlassTerra says it is collaborating with a global satellite connectivity company to conduct a proof of concept project to monitor a key embankment in real-time at the former-operating Mount Morgan mine.

Mount Morgan, which was a copper, gold and silver mine that operated up to 1981, is now abandoned and managed by the Queensland Government’s Department of Natural Resources, Mines and Energy.

GlassTerra has installed one of its Internet of Things LiDAR sensors at Mount Morgan to demonstrate the safety benefits of real-time tailings embankments monitoring. The collaboration will showcase the integration of this technology with GlassTerra’s geospatial platform and global satellite connectivity to achieve highly reliable real-time monitoring of tailings embankments, GlassTerra said.

GlassTerra Chief Customer Officer, Sophia Li, said the combined solution will demonstrate the ability to conduct real-time monitoring of unplanned movements of earth and other parameters, on embankments such as tailings facilities.

“Real-time monitoring of embankments enables prompt reporting, investigation and mitigation of any changes, which can enhance safety, improve the protection of our environment and advance the social performance of the mining industry,” Li said.

It also has potential applications in the 3,500 tailings storage facilities in the global mining sector. This project has already led to GlassTerra securing a contract for real-time tailings embankments monitoring in Africa, the company said.