A New Way to Mine Diamonds
April 21, 22
There have, traditionally, been two main ways to get diamonds out of the ground - open pit mining and underground mining. Now there's about to be a third.
Canada's Ekati diamond mine is planning to flood an existing pit and use an underwater crawler to mine the ore.
It's a potential game changer, harnessing existing technologies to significantly extend the life of an otherwise unprofitable deposit.
Ekati, the country's first commercial diamond mine, began production in 1998 but new owners, the Arctic Canadian Diamond Company, knew it would reach the end of its life in 2024 unless they did something drastic and innovative.
So they hit on the idea of underwater remote mining (URM), which they hope will go live at their Sable deposit in 2026.
It combines existing technologies to allow cost-effective mining at a deposit that would otherwise be commercially unviable. Open pit mining involves shifting huge volumes of waste - at Sable it's seven tonnes of waste for every tonne of ore. So once the higher value kimberlite has been extracted, there's comes a point where it's no longer worthwhile.
It's a potential game changer, harnessing existing technologies to significantly extend the life of an otherwise unprofitable deposit.
Ekati, the country's first commercial diamond mine, began production in 1998 but new owners, the Arctic Canadian Diamond Company, knew it would reach the end of its life in 2024 unless they did something drastic and innovative.
So they hit on the idea of underwater remote mining (URM), which they hope will go live at their Sable deposit in 2026.
It combines existing technologies to allow cost-effective mining at a deposit that would otherwise be commercially unviable. Open pit mining involves shifting huge volumes of waste - at Sable it's seven tonnes of waste for every tonne of ore. So once the higher value kimberlite has been extracted, there's comes a point where it's no longer worthwhile.
The key benefit of URM is that the vast volume of water holds the pit walls stable. Miners have to strip away concentric circles of worthless earth simply to prevent the walls collapsing, but if the water does that job, you can dig deep into the ore body, rather than digging wide.
Filling a pit with water and developing a floating platform and underwater crawler to mine it require significant investment, but there was no alternative, says Rory Moore, CEO at Arctic Canadian.
"We're doing this out of necessity in order to extend the mine life at Ekati," he said. "We have to do something innovative or it's going to be game over. If we did nothing Ekati would finish up in 2024.
"We are at the cutting edge and people are looking very carefully at what we do. If we make a breakthrough here it's going open a lot of doors for people to extend their mine lives."
The first step will be to fill Sable with water - a huge operation that will take two years, piping in 23m cubic meters from Lake Exeter, 17km away. Then they'll lower the underwater vehicle to the bottom to start work.
The crawler has a drum at the bottom with teeth that allow it to mine 600 tonnes of ore an hour as it circles the bottom of the pit, layer by layer.
"It mines in a systematic pattern, layer by layer of kimberlite." said Moore. "The ore gets pumped up as a slurry to the surface and goes to a de-watering plant. We then stockpile the ore and transport by road train to the process plant."
It will be the first time such a system - a floating platform, an underwater mining crawler and a land based dewatering plant - has been used to recover diamonds from kimberlite.
Netherlands-based Royal IHC, suppliers of maritime technology, will build the URM system, which has been described as a "technological breakthrough".
It draws on systems currently used to lay underwater cables, mine other mineral commodities and retrieve marine diamonds and is being built by Netherlands-based Royal IHC, suppliers of maritime technology.
The costs of underwater mining will be "considerably lower" than open pit, and all the more so compared to underground mining, which is complicated and very expensive.
"If it works, it potentially makes Ekati economically viable for the next few decades," said Moore, providing ongoing job opportunities and socio-economic benefits for indigenous groups on the edge of the Arctic Circle."
Arctic will complete a 150,000 tonnes production trial at the mined-out Lynx deposit in the summer of 2024 and, if all goes well, the crawler will be transferred to Sable, extending its life by four years.
There are also plans to use URM at the neighboring Fox ore body, which would potentially give Ekati another 10 years of mine life.
The technology is only suited to a certain hardness of rock. Ekati's ore is at the sweet spot, not too hard, not too soft. But despite that, URM could well prove to be a game changer, and other diamond miners will be watching with interest.
Have a fabulous weekend.