Testing of the SMD method at Anaconda’s site in northern Newfoundland will continue into the fall.

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F ive years ago Allan Cramm, vice-president of innovation and developmentat Anaconda Mining, met Stephen Butt, a process engineering professor atMemorial University and head investigator for the school’s Drilling Tech-

nology Laboratory, to discuss drilling issues at one of Anaconda’s gold miningprojects in Newfoundland. That visit was the catalyst for an industry/academiacollaborative project that would create a technology that has the promise toextract gold from otherwise uneconomic, steeply dipping narrow vein deposits.

They could not have anticipated that what came next – Sustainable Mining byDrilling (SMD) – would gain the attention of mining companies from around theworld, eager to be among its first adopters and drawn in by the potential forimproved safety and environmental performance, along with the financialrewards offered by the technology.

Narrow veins, big challengesIn the mid-1980s, exploration in Newfoundland led to the discovery of many

narrow gold veins, including at Anaconda’s Point Rousse project in northeastNewfoundland. According to Cramm, these stranded veins across the provinceare part of a larger resource estimated to have an in-situ worth of as much as $5billion. “I’ve always been intrigued that they represent significant value, but a lotof them haven’t been developed because it’s not economic,” said Cramm.

Frustratingly, mining these veins using modern conventional methodsrequires a similar level of investment in time and money as a large mine. “Eventhe smallest conventional mining equipment requires 1.5 metres of width to

Thegolden

key?Collaboration betweenAnaconda Mining and

Memorial University could unlock narrow-vein gold

deposits around the world

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rows established real-time high-resolution sub-surface imaging from the construction industry,which directs the drill while simultaneouslymeasuring and mapping out the vein. “It pro-vides a high-resolution picture that animateswhere we are in the vein,” said Butt. “And itgives us confirmation about the continuity of thevein that we can use to build up a 3D model.”

Once the pilot hole has been drilled, progres-sively larger hole-openers are used to drill – andmine – the ore. This technology was adaptedfrom large diameter drilling that pumps drillingfluid at a high velocity through the drill. Conven-tionally, the fluid forces the cuttings up to thesurface through the hole, but a hole the sizeneeded to drill a narrow vein would require theexpense of massive amounts of fluid and verylarge pumps.

To cut those costs and improve efficiency, theSMD team added compressed air to their design

and switched to using the drill pipe instead of the hole to getthe cuttings – in this case the ore – to the surface. “Eventhough it has the cuttings in it, the air reduces the densityand it rises through the inside of the drill stream by buoy-ance,” said Butt. “The cuttings are returned in the inside ofthe stream, which is a smaller area than the hole itself andthat takes away a large part of the requirement for the fluidvolume, and it ensures we don’t lose any cuttings in any frac-tures or fissures in the rock of the open hole.”

The methodology works on a vertical lift of about 300metres. The drill, which is electric, delivers an already crushedslurry to the surface, which translates to instant savings in pro-cessing. Once the vein has been mined, the hole is refilled withbackfill or cement and covered, barely leaving an environmen-tal footprint. The method does require a settling pond onsiteto handle excess water, but no harmful agents are added to thewater. All this for an estimated 50 per cent of the cost of con-ventional mining methods.

“The technologies themselves come from a number of dif-ferent sources,” said Butt. “Oil and gas is one. Large diameterdrilling from construction is another. Downhole subsurfaceimaging comes from various other industries,” said Butt. “Sowe’ve taken relatively mature technologies from other indus-tries and put them together in a package along with some newinnovations.”

That helps limit the technology risk for early adopters. It isalso the shift in mining from big and bulk to selective and pre-cise that has many miners excited. The project was supportedin part by research funding from the National Research Coun-cil, the Atlantic Innovation Fund, as well as from the New-foundland Labrador government.

The excitement spreadsIn March 2019, SMD was named one of the three finalists

of the #DisruptMining competition. Anaconda began hearing

operate,” said Cramm. “So when you are going to mine a nar-row vein, you have to open up that 1.5 metres. The vein couldvery well be a half a metre thick and you are excavating threetimes as much material as you need to. Plus, you have todevelop access to the ore zone. If you have a vein that is 200metres deep, you need to develop a ramp to the bottom of themineralization that would be 2,000 metres in length, assum-ing a -10 per cent gradient.”

Steeply dipping veins are also challenging because of theirshape. “There are other drilling methodologies for recoveringthe ore, but these involve drilling straight holes at a particulardeclination,” said Cramm. “These methods don’t follow thechanging shape of the deposit. If it’s a mass deposit that doesn’treally matter much. But when it’s a narrow vein that changesshape, thickness and dip, it is critically important.”

Butt – whose Memorial University contact details desig-nate him “King of the drill” – also became intrigued by thechallenge and the possibilities. “Much of the focus of my workhas been on industry collaboration and technology develop-ment largely around drilling and, in fact, subsurface imagingfor the mining, oil and gas sectors,” said Butt. “It was a veryfortunate meeting.”

The men spoke for two hours about narrow veins that day.It was the first of many conversations. Within a year, Ana-conda had put Cramm on the project full time to work withButt and a team of researchers pursuing their graduate studiesat Memorial.

Drilling for a solutionThe team zeroed in on building a drilling technology that

follows the trajectory of the vein. Reminiscent of an oil rig,SMD mines the vein completely from the surface. Theprocess begins with an inclined mast drilling rig driving apilot hole in the centre of the vein, between the hanging walland the foot wall. But it does not drill blindly. Instead, it bor-

The concept relies on a number of borrowed technologies from other industriesincluding subsurface imaging.

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from other mining companies. “We have been looking at thetechnology to solve a challenge we had here on some of ourdeposits that had no economics,” said Cramm. “But #Disrupt-Mining made us aware the opportunity is around the worldand that it can be used to not only mine veins that are exposedon surface, but also to access veins that are peripheral tomined deposits and had never been considered because theywere quite small with no economics.”

They also heard from miners wondering if the surface tech-nology could be applied to underground projects. “It is funda-mentally the same concept, but we could use smaller drillingequipment that would be more suitable for undergroundopenings,” said Butt.

One of the companies that connected with Anaconda wasHochschild Mining PLC. The value proposition is clear toRamón Barúa, the company’s CFO: “Becoming more efficient,reducing the environmental impact and substantially improv-ing the safety of the workers involved in the undergroundmining process are all aspects that are significantly improvedby the work that Anaconda is leading.”

“This is exciting,” said Asante Gold Corporation CEO Dou-glas MacQuarrie. His company is looking to use the technol-ogy at its Kubi gold project in Ghana. “Conceptually andtechnologically, there is no reason it shouldn’t work.”

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He said he believes SMD could do for mining what frackinghas done for oil and gas and sees the economics of SMD pro-viding a powerful boost for junior gold companies such as his.“I see an opportunity for leasing the equipment,” he said. “Ithink there’s a huge opportunity here for proof of concept. Ifone drill rig is profitable, you phone up the contractor and sayyou want four more.”

He estimated that SMD has the potential to recover 40 to50 per cent of the gold at Kubi just with the drilling. “If 50 percent of the gold is recovered in the crushed material, that’s halfthe cash flow right there,” he said. “And that means the otherhalf is in the tailings and can be recovered at a nearby mill.There’s the other half of your cash flow.”

Next stepsThe SMD team is conducting more extensive imaging work

at their test site this summer. “And if all goes well, by the end ofSeptember, we will have a commercial production unit [at oneof Anaconda’s narrow veins] for drilling field trials,” said Butt.

Meanwhile, MacQuarrie wants Asante “to be prepared tomove on a prefeasibility scoping level study,” he said. “The testought to pay for itself because the secret to this technique isyou have direct recovery of the ore. The drill cuttings arealready crushed and ground.” CIM