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Studying ways to rejuvenate old mines

Nathan VanderKlippe
Northern News Services

Yellowknife (Aug 26/02) - A geologist with the C.S. Lord Geoscience Centre, Hendrik Falck is a recent recipient of a Julian Boldy award for a paper he and colleague Brian Cousens drafted on the region's geology.

For the last five years, Falck and a group of 20 geologists from across the country have been studying ways to rejuvenate old mines with new scientific techniques.

Yellowknifelife: Can you give me a brief, English-language executive summary of what you studied?

Hendrik Falck: In a nutshell, we went around and collected rock samples from all of the different rocks around Yellowknife. And doing a variety of different chemical analyses on these rocks, we were able to tell that the rocks on the west side of Yellowknife Bay were never really connected to the rocks on the east side of Yellowknife Bay. The west side here is an old volcano, so you had magma pouring up. Picture Hawaii with lava pouring out.

Yellowknifelife: Hawaii with snow?

HF: A little cooler, but still Hawaii. And the east side is all ocean muds. The chemistry that we did shows that the two were never together, they're quite different rocks on either side. What it means is in between the two is a big fault, an old fault, sort of like the San Andreas. But it's not moving anymore. It hasn't moved for probably two billion years. What's important about these big old faults is gold comes into an area as dissolved gold in water, so it needs a pipe to get collected and come into a single place. These old faults often act as piping conduits. They take the fluids, collect them and move them. Eventually the fluids get cold and the gold precipitates out. By finding that there's a big fault in between the two, it means that we've sort of identified the basic plumbing system (and) why the mines are in the Yellowknife area.

Yellowknifelife: And this is all new knowledge?

HF: There have been some people who have thought about it but they really haven't had sort of any real good evidence to point this is where that crack really is. This work basically allowed us to point to that crack. And now we're able to trace that crack basically up north towards Discovery Mine and further south under Great Slave Lake. And so this gives us a good idea that there's a good chance that there's other deposits along that route.

Yellowknifelife: The assumption to a layman would be that you could mine all along that fault.

HF: What happens is certain parts of it become openings so water can get through. The rest of it is just like if you have (stacked) pieces of paper and try to get water through that and you can't squeeze it through. You need openings for the waters to get through and make the deposit.

The bigger the structure the bigger the mines generally are and this one is a fairly big crack. So there is a chance of finding another world-class gold mine in this area.

Yellowknifelife: Is there anything that you've discovered that might lead to an extension of life for these mines in this area?

HF: Yes and no. That comes somewhat down to corporate climate and the gold price. If it climbs back into the $320 US area it becomes more economic here and then yes, I think Miramar would be interested in extending the life.

Yellowknifelife: We've got prospectors traipsing all around the North looking for stuff. If I'm a prospector, does this mean that instead of looking at a map as a big circle and saying, "well maybe I'll put a grid on it and look everywhere," suddenly I can draw a little line down the centre and then I look along that line. Is that what happens?

HF: That's certainly what happens. Clues like this that there might be a better zone, they've been sort of intrinsically understood by a lot of prospectors. But this will focus a lot of their efforts.

Yellowknifelife: Any idea what the monetary value of being able to map this is?

HF: We're on the order of about $250,000 per year for each year, with all the contributions by Miramar and so on (in program costs). If it extends the life of a mine by a couple of years, we could be talking a payback well into the millions of dollars. Generally, the rule of thumb that has been used is that for geoscience expenditures in the Northwest Territories, you generally get a five-fold increase in the money back. If we spend $250,000, we can expect at least a million and a half back in terms of productivity.

Yellowknifelife: So over five years, over seven million?

HF: It's never an instant payback. All it takes is for Miramar to drill a few holes, find another couple of stopes and another million ounces at $200 an ounce. You can sort of do the math fairly quickly. A million ounces is a seventh of what they've mined at Con already and an eighth of what they've mined at Giant. So we're not talking about huge here, but you can start seeing the money involved.

One of the people who is writing a chapter for our final volume, Malcolm Robb at Indian and Northern Affairs, calculated out over the life of Giant Mine exactly how much money that mine has made. It's on the order of $2.5 billion it's contributed to the economy of the NWT. Which puts it on par with Ekati, essentially.

Yellowknifelife: This is fascinating. What about for you?

HF: I think it's great. I like geology because it's like being a detective and solving a mystery. You're given a series of rocks and your job is basically to come up with a story of why are they the way they are now.

The other part of geology is invariably you're wrong. In 10 years, someone else will come along with a better story and change everything. But that's part of the fun. You do as much work as you can and you put together the best story that you can.

Yellowknifelife: Can what you found here be extrapolated to other areas of the North? Can we say, "well maybe we've got the same thing going on at Lupin"?

HF: Lupin's a little bit of a different rock type, but what we're learning in this area will certainly help people like Miramar at Hope Bay. And some of the researchers that we've had working in Yellowknife on our project have been in the meantime hired by people in Timmins, Ont., to do exactly what they were doing here in their gold mining camp. And that's the whole purpose behind these EXTECHS, is to try new things that companies might be reluctant to try because they're expensive or experimental. You try them in an area where it's a lost cause anyway. If the results are encouraging, then we'll try to export this technology to other areas that can use it as well.

Yellowknifelife: What technology is that?

HF: For instance, we applied a number of different chemical techniques that aren't as widely applied in a lot of mining camps. A lot of our information is being integrated into two GIS's (geographic information systems). One's a computer model, just a map basically. But the other model that we're working on, which is really quite exciting, is putting all of the information for Con and Giant into a computer system so that you can see where the gold is now. You get a computer model and you can rotate it. Then based on that model, you can make extrapolations where more gold might be, showing how that technology can be used in an old mine. What we're doing is trying to show that it is worth it (to develop computer models), especially in the case of an old mine. You've got the mill here, you've got all this ground permitted. You've made the mess already, why not extend the life of the mine by five, 10 years, get more gold out of it? You make more money that way than trying to build a new mine which costs a lot.

Yellowknifelife: It must be quite an honour to get an award like this.

HF: It was a great surprise. I was really humbled. For me, especially, because the guy it was named after, Julian Boldy, used to work at Giant in the '60s. He did some fabulous research there. He just had a unique way of looking at the rocks and really a wonderful grasp for geology and how to put very scientific observations together and build an economic story out of that. So to be given this award with his name on it is very gratifying.

Yellowknifelife: Any monetary award with this?

HF: I think there's a little one, enough for a bar tab. It's a token, but the honour of getting it is the important part, basically. It's somewhere around $50 or something like that.

Yellowknifelife: That's hardly enough for a celebration bar tab.

HF: (laughs) Celebration in Saskatoon, maybe.