22: Bjørn Thomassen – Mining the Black Angel

In this episode, we hear more from Bjørn Thomassen, emeritus senior scientist from the Geological Survey of Denmark and Greenland, about his time working as a geologist and later a mine inspector at the Black Angel lead zinc mine in west Greenland.

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22: Bjørn Thomassen – Mining the Black Angel

Based on interviews held on September 30 – October 2, 2019 in Copenhagen, Denmark            

Note: Polar Podcasts are designed to be heard. If you are able, please listen to the audio, which includes emotion and emphasis that is not evident in the transcript.

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Bjørn 0:01

I never had a car, but you had to drive a car there. And you must imagine in, in such a mine, this mine, there’s no light whatsoever. So the first time I was driving the car up there, I was scared to death.

Julie 0:12

Welcome to Polar Podcasts, where you’ll hear stories from geologists who’ve spent their careers, their lives, exploring and studying the remarkable and remote geology of Greenland. Why did they become fascinated with Greenland? What were the problems and the discoveries that drove them? And what was it like working in these remote places, where few people venture, even now? I’m Julie Hollis.

In this episode, we hear more from Bjørn Thomassen, emeritus senior scientist from the Geological Survey of Denmark and Greenland, about his time working as a geologist and later a mine inspector at the Black Angel lead zinc mine in west Greenland.

Bjørn 0:54

So the Black Angel er, that’s a beautiful name, on a beautiful er, figure on an 1100 metre high, near vertical mountainside er, 18 km east of Uummannaq. And it’s, yeah it’s angel like, you could also call it eagle. It looks like some bird and it’s formed of black mudstone, hosted by white marble. So it stands out. It’s a very good name.

And er, near that angel figure, in the marble surrounding it, there’s a rich deposits of er, lead and zinc. The(re are) two names, Black Angel, Maamorilik, because at the other side of the, this er, mountain face, the point, actually between two fjords, where they used to (be) quarry marbles in the 30s and a bit later. And that place is called Maamorilik. And that is where the mining town was built and the mill for processing the, the ore and, and also the harbor facility to, to ship out lead and zinc concentrate.

I worked there as a mine geologist for two years from 1985 to 87. And the ore is situated er about five hundred metres above sea level inside the Black Angel mountain. It’s actually outcropping, you see the sulfides, which are galena, sphalerite, and pyrite, you can see outcropping below the angel, there’s a rusty horizon.

To access that er, mine, the mining company, which was a Canadian company Cominco, they had to build a cable car station. And the cable car was still the only access to the mine. So what happened was that tunnels were excavated following the ore. And the way you mine ore, you, you have a tunnel. At the end of the tunnel, there’s a face and that face should be in the ore, so you drill in. You have a jumbo drilling machine drilling holes. And they’re filled up with, with explosives and, then during the night, there’s a team walking around in the mine and igniting all the er, explosive charges. There’d be ‘bang.’  And the tunnel will advance three and a half metres. And er, the floor is filled up with broken ore, which is then shifted to shaft and transported by trams, small trains at the lower level and eventually there’s a coarse crusher and the crushed ore is eventually sent down to Maamorilik by the cable car. This is a car that can take 40 tonnes of ore.

It was running day and night, 24 hours. And er, it should produce er, transport two thousand tonnes every twenty four hours. If not, there was a panic because there was only a buffer, that means store room, for two days production down on Maamorilik. So when the cable car was stopped, and it was stopped when it was blowing too hard. There was a speed limit, 25 second metres, it was not allowed to transport er, people in the cable car. And then the higher speed, can’t remember what, the cable car was not allowed to run at all because the wind was across in the fjord. So when there was what they called wind speed stop, everyone was going in panic because if that was going to be for more than 48 hours, the buffer of er, crushed ore, raw ore down at the mill would be empty and then the mill would stop. It would take a week to get it running again. So there was desperation.

I remember one Christmas night when there was windspeed. And the cable car was not running. There was the shift, day shift. There were two shifts of ten hours, a day and a night shift. They had to stay overnight at December 24th er, up in the mine. There were no rooms. There were tea rooms. But it was rather rough because of windspeeds. So very dramatic.

But apart from that, life as a mine geologist was er, there was this routine that in the morning I went up with the cable car and took my way round in the mine. And  we were four geologists in the mine department at Black Angel. There was a chief geologist. He was mainly sitting in his office er, calculating ore reserves and recalculating and subtracting every day’s production. And that was the key point of course, ore reserves. And that was the responsibility of that small department. And then there was, four, there was always one on, on holiday. We worked four months in place, one month er, paid holiday. And there were two foot geologists left and we shared the mine between us. And there were about a hundred fronts of (in) the tunnels where the production (was going on), so we had half each.

Bjørn 5:37
So when you came up, there’s a small Toyota pickup and they would drive there, driving a car. I never had a car. But you had to drive a car there in the mine because it was hundred kilometre tunnels (and) at that time in the mid-eighties, I mean the mine operation started in 73. So it was a mature er, mine when I came up there. So there was a lot of old abandoned tunnels er, adits there. And you must imagine in, in such a mine, this mine, there’s no light whatsoever. So the light you had, that was only the headlights of the car and then you had of course a hard hat with, with a small lamp. So first time I was driving the car up there, I was scared to death. I was, it’s in permafrost, so it’s er, it’s cold up there. About minus 4 degrees, which is very good for mine stability by the way. But I was soaked with sweat of the shear fright to drive into that and how to orientate yourself. There’s some, some maps of course, mine maps. But they’re working things. They’re filled with, you know, figures and er, and lines and old lines.

Anyway, I got used to it and then I was controlling the various stopes and (where) faces and, and the very important job, it was ore (grade) control. So I should see to that what was mined by the miners, that what they took out, what we called ore, it fulfilled the quality parameters. And er, so I went around measuring the thickness and in doubt about the concentrations, the metal concentrations, you take a chip sample. But those people standing by you in the jumbo, they wanted an answer here and now. So you just shoot from the hip. You have to stop here because the ore’s not good enough. It should be at least eight percent lead and zinc before it was economic to shoot it. If not, you should leave it.

Then I had this, when I thought this is poor, I had this er you know paint, spray paint, so I’d write red letters, “S-T-O-P.” So they were not allowed to go (on). And I’d also discuss with the foreman, they were operating in teams with a foreman for each of those. And I talked with the foreman for each of those. And er, I said to him, “Oh, that one. It can continue the ore will be good, it will continue so just carry on.” And then when I come up next day, they had drilled and blasted and it was very interesting to see whether what they have found what they had blasted out, whether it was real ore or grey rock, what we called waste. I mean, in the mine there were two things, there was ore and waste. Everything which was not ore, that was waste.

Then in the middle of the day I took the cable car down to the office, sitting there and then I wrote report to the mine bosses er, with recommendations, ‘And I have stopped that and that stope but you should continue, follow the ore and you shift to (the) left.’ They could move the tunnel left, right, up and down to follow the ore into the mountain. And er, I did that and I took care to, to make drawings, drawings of the faces. But then, when you come up next day and came in and I said, ‘Well the ore continues, you just take another round here.’ Came in I saw a face, white face, pure marble, no sulfide at all. That means money out of the window. It was more or less guesswork and experience. But there, they would let you know if you had, if you had failed. It was a very exciting everytime. But I would say of my time in Black Angel: it was the most professionally exciting job I had because you had this, this very day-to-day (decisions), they hold you accountable for what you have written in your daily report.

In principle it was running year round because moneywise and as I said, the flotation, the mill had to be fed continuously because stopping the mill, they would sack you. The same with the chief geologist. If he hadn’t calculated the ore reserves er, at a certain date after the first of the month, I mean the first Friday in the new month then he was sacked, I mean, it was, everything was built on ore reserves. And it was a funny thing because the geologist department, the small department is of no esteem because everybody is earning more money, the miners earning much more money than the geologists and the engineers of course. And the engineers, they decide everything in the mine. And the geologists, they were some funny people. They could just look after themselves. But  we were drilling all the time for new ore. And then we were stock-keeping on the ore reserves. And all er, economic calculations were based on the production and ore reserves of course. And we were the stakeholders of those things. So we were very important. But on the other hand, you can’t, we tried to explain the mining engineer(s) (the best) layout. If you mine er, go into (an) ore zone - this was room and pillar mining, meaning that it’s underground mining and you can’t take out all the ore because then the roof will collapse. So you had to leave some pillars to support the roof, and say we have a flattish ore, but it was not equally thick. So we thought the smart thing was to put the pillars in where the ore was thin, er and mine the surrounding room where the ore was thick. And we were measuring the thickness with you know measuring thickness all the time and put it into a computer, we had a database. So we had hold on the thickness of the ore. We did it electronically by the way. That was er, in the, started in the early eighties, (an) electronic ore reserve er, database used for calculating. That was very state of the art in those days.

I remember we came to, when Boliden, Boliden, a Swedish company bought the mine in 86 and we went on a study, colleague and me, a study tour to Boliden and I remember we came to the main office in Boliden, you know big Swedish company, and they had quite good confidence with themselves, you know, Swedish quality and so on (we know them). And they’re skilled, there’s nothing wrong with that. But then we were sitting in the main office in er, in Boliden town asking, “Could we see how you handle you, your, your ore reserve er,” because we had everything in a computer. And he didn’t like it. And then he took a large book. And there it was, written in with pencil. So they were behind there. But that was how we did (do) it, all through the early eighties.

Now everything in that place was about production and ore reserves. The role of the geological department, we had free hand to er, drill for (new ore) er, whenever you got an idea. (The) documentation of the ore (was) before they started mining: they had done systematic drilling er, with a fixed space, fifty metres or something. And documented, and that was documented on, in sections, which was drawn up on, on mylar. Nowadays you’d do it in a computer. Those days it was a hand drafter sitting doing that work all the time. And if you got an idea either (from) what you saw in the mine or what you saw in the sections, that in there there must be more ore, then we had permanent (up there) two, three drill rigs (up in the mine). So we just made a layout for drilling, gave it to them (the drillers) and said, “You drill for more ore.” And that was, that was a fun part (of the job), of course. To try. And that was quite successful because the mine started out with a proven ore reserve of four million tonnes and eventually we ended up with mining eleven million tonnes. And there was one million tonnes left in pillars and stuff. So we managed to triple the ore reserve during production. That was great fun.

Julie 13:03

After two years working at Black Angel, Bjørn left for a position with the Geological Survey, working in South Greenland, which you can hear about in the next episode. After that, he applied for a position as a mine inspector with the survey.

Bjørn 13:16

So er, I applied for a, a job then er, which was vacant and that was as a mine inspector for er, the Black Angel mine, which I had left a year previously. So I know that mine, I knew that mine. And er, that was great fun. I came up now er, as official representative of the system, the state system, which has issued the, the licence. That means empowered to close the mine if they didn’t fulfil the, their commitments. So I could travel up four, four times a year, after my choosing, and went around in the mine and what I should control was essentially ore reserves and er, ore production. And I could tell a lot about what’s happened with the, with the production because er, the mill was constructed to process 800 thousand tonnes of ore a year, resulting in, I can’t remember, 150 thousand tonnes of concentrate, lead and zinc concentrate, something like that.

Problem was, there was a team monitoring the, also from the state, environmental people, the, the environment out in the fjord and they have put restrictions on the production because the thinking was when the mill was running on full capacity, 100 percent, there’d be more pollution. So they had cut it down to (tell you should only let it run on) 95%. And it (that) was controlled officially, both (how much concentrate,) how much ore came into the mill and how much concentrate and waste came out. And I had to report those figures. They were official, so I put up tables on that. And for some reason, there always came more ore into the mill than they had concentrate out or, it didn’t fit out. Because we could see er, geological department er, measured what had been mined of the mine, simply subduction daily production from ore reserves. And then there was the weight of the crushed ore which came into the mill and which also weighed the concentrate which came out. And it didn’t fit out. And I, I can’t see (understand) it, I mean my impression was that those er, engineers, they couldn’t bear to let the mill (to) run not on full capacity, (why shouldn’t they). And then they manipulated the, the weight, somehow. And when I saw that first time, I said to my boss, “Eh, something’s wrong here, they’re cheating.” “Shh. We know that, we all know that. Don’t say to anyone, Just leave your figure in the table because nobody will understand it.”

And er, they had employed a mining engineer (rock mechanic) at the company. He did nothing but monitor stability and several (other) factors. But what he did in principle, he had stations around in the mine and he had a wire coming from the roof and a fixed point at the bottom. And the distance between the loose-hanging wire from the roof and the fixed point at the bottom, he measured the distance, five centimetres. And he came every day. So er, with a micrometre, he could measure. And the thing is, if the roof is coming down, it won’t do it at once, it comes slow, and it measures in millimetres. And he put that in his er, computer, so he could draw maps and he could see where in the mine do we have a larger convergence than in other places.

He also mapped out the pillars, whether they were breaking up. If they took too much load, they would, you could see they were all criss-crossed by cracks. And the worst scenario, that was what they called domino-pillar collapse. And you can imagine a situation, there was a very large room in the old part of the mine, which had been mined out, with pillars 30m high. When you were (are) standing there with (you had) your lamp on (and) your hard hat and looked up (there), you couldn’t see the roof. Anyway, they were afraid if the pillars were gone, one was gone, there would be more pressure on the surrounding pillars, so they will yield also, and they could yield so there would be this domino pillar collapse, where, “phhwwit.” And everything would collapse. And that was the worst case scenario that should be avoided.

And that came to er, a very interesting er, choice at the end of the life of the mine. They wanted to mine the big pillars in the (so-called) Pillar Room just inside the mine, the 30m high pillars and they were thick. So there was half a month’s production in one pillar. And we as, as the society, the state, we had to look for safety and we sought all sorts of guarantees that if we allowed them to take if we allowed them to take the pillars we should be sure we wouldn’t have this domino-pillar collapse. So the requirements we put up, we said, you should fill up with waste so that if the roof er, collapses, it will fall down on the waste. So er, marble, pure marble was transported in and water was er, sprayed over it, which froze it so it stabilized, and then they tunneled in ten metres below the, the pillar and from there they drilled up(wards) and, in the pillar, and then they made one big explosion and the whole pillar went, ‘phwit,’ down ten metres through the floor and ended up in a big heap in the tunnel below and they could, they could drive it to a shaft and further to the mill. It was very good ore.

And then this technician, this mine engineer, he went out and looked at his stations, how much, now that we’ve taken that very big pillar, they all had names of course the pillars. How much has the roof come down. And you have to have a time effect, there’s a time factor too. You have to wait. So we had to set up rules. You can’t take the next pillar until we have waited three weeks or something. And that was (hold up with) weighed at the end time of the mine er, against how long should we let the mine, or should the company, the mine running. That was a huge investment of course with, with salaries and equipment and, as they were not allowed to sail in in the winter months. Everything, all sort of equipment and stores er, for and fuel and things should be brought in in summer time. So at some time they had to stop mining when they couldn’t secure ore enough. So we were up against that. Also as a society we want the mine to be as empty as possible. That’s best for society. On the other hand, we had the risk, safety risk. And I weighed that and there were some very interesting discussions.

Another very interesting thing in that mine there was a water problem. In most normal mines you pump, pump water. But here, Black Angel, that was in permafrost, minus 4 degrees. So all water was frozen. No problem. So they were mining happily and the chief engineer (geologist) said, ‘Now we’re in permafrost but the permafrost is going to end. You watch it.’ They were tunneling (after a new orebody.)  From surface drilling they (had) found a very good deposit under, below the ice called the Dep Ice Zone. So they were going to hit that with a production tunnel, boom, boom, boom. Chief geologist said, ‘You might come out of the permafrost’. And suddenly they came out of the permafrost and the water was (standing) under pressure, because there was three hundred metres of rock and ice on top, and there were those (water-filled) cracks and things when you are out of the permafrost.

So the whole mine was flushed over 7 km, and er, water was coming out of the mine opening, just opposite the mining town in Maamorilik. So the authorities - that was before, just before my time - they stopped mining. They said, now we have an environmental catastrophe. So they had to stop the mine,  (the water,) and it took them a year because how do you stop water flowing? It’s so difficult. And in the end they injected er, concrete and they made the tunnel out to this Deep Ice Zone. It was beautiful, rich, very rich ore and they got it mined but very costly. But every round, three and a half metres they moved forward, they had to inject the surrounding with concrete. And (then at the end of the mine(s life), the environmental people, biologists, and every) they also diverted the water, it was flowing out another opening because you can’t stop water, it has to flow. (But even though) When mining ended, the biologists said: now mining company (they have a) there are requirements when you stop mining. So they had to remove a waste dump going into the water, but they also had to stop the water flowing out of that other outlet. It was just diverted and flowing out, pure water, but you never (once) know, they (would) were afraid that this (outlet) would freeze out, so the water would (continue over that and) flood the whole, whole mine. Problem is er , all over in the mine there is galena, crushed galena on the floor because of the trucks, they’re always losing some of the ore on the floor so it’s generally very polluted. Lead is of course a big polluter.

So (the) environmental people said, decided there should be built a wall er, to keep the water out of the, the mine. And they asked me as a geologist, you show us where there are no cracks in the rock. So I looked at the mapping and found a place where the mapping geologists put no cracks on. I said, ‘You put it here’. And we had warning. I was at that meeting and our rock mechanics, Norwegian genius, very nice person er, and he kept saying to the biologists it’s, this meeting here, it’s a waste, I remember, “It’s a waste of your money and my time to build a wall there. You can never keep the water back.” But they, they insisted. The state required (that) the company (you must make) made that cement metre thick wall. So they built the wall and there was a nice tap and I remember the foreman who, he was very proud of his, his great work. It was 7m thick in that tunnel, plug, real concrete plug there and a tap you could open. And then we came up a week later. There was just as much water floating past. It came out of all sorts of cracks (in the wall). Because the water was under pressure. And the (was) marble was (and) filled up with cracks. And it’s still flowing. And then they gave up, the biologists. But the expert, he had said at that meeting, very distinct, “You’re wasting my time and your money”. 

Julie 23:39

I’m Julie Hollis and you’ve been listening to Polar Podcasts.

Julie 23:49

In the next episode, we hear more from Emeritus Senior Scientist Bjørn Thomassen about running a field program on a cliff face, exploring the niobium- and tantalum-enriched Motzfeldt Intrusion.