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Massive landslide damages Kennecott's Bingham Canyon Mine in Utah

Discussion in 'Mining/Aggregates' started by leisureexpress, Apr 12, 2013.

  1. leisureexpress

    leisureexpress Well-Known Member

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  2. Nige

    Nige Senior Member

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    I've seen the photos. Reminds me a bit of the major slip they had in Freeport McMoran's Indonesia operation about 10 years ago. Apparently at Kennecott they'd been monitoring the ground movement for 2 months or so, so they knew it was coming. From the photos I've seen there appears to be about 10 haul trucks and a shovel in one area, a shovel in another, and a boom truck in a 3rd, but that's only what I can see - other stuff may be buried totally out of sight.
     
  3. leisureexpress

    leisureexpress Well-Known Member

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  4. Birken Vogt

    Birken Vogt Charter Member

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    How do you suppose they go about stabilizing and remediating this? It looks like a near vertical face around the top of the slide hundreds of feet high; you couldn't get anything or anybody near it for fear of further collapse.
     
  5. Nige

    Nige Senior Member

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    Start from the top and work down benching it as they go would be my guess. That's what they did at Freeport.
     
  6. CAT793

    CAT793 Well-Known Member

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    How do they have 2 months to plan for this and still loose several 'Yellow Utes' at the bottom of the pit.
     
  7. Nige

    Nige Senior Member

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    I guess timing of the final collapse came as a bit of a surprise by the sounds of the story and from what I'm hearing on the jungle drums (we have ex-Kennecott people working at our place). The mine has a fleet of around 150 trucks so losing 10 of them (albeit temporarily until they can knock a road down to them and get them out) won't faze them too much I would guess. The mine was still producing all the time since February that first warning came that the slope was moving, and obviously they need trucks & shovels in the pit in order to achieve that. My guess is that they will have been stockpiling ore like it was going out of fashion next to their plant for the last 2 months and that's what they'll be throwing in the primary crusher until they can get ore from the pit again.
     
  8. digger242j

    digger242j Administrator

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    One news story I saw says that the slide was larger than they'd anticipated.


    http://fox13now.com/2013/04/12/bingham-canyon-mine-slide-bigger-than-anticipated/


    For those more familiar with how such mines are operated, can I assume most of the material that slid was spoil, from which the good stuff had already been recovered, and overburden? And if so, was it all stacked on undisturbed ground, or do they begin by stacking it on undisturbed ground, and then re-fill the older part of the pit as they move forward into fresh ground?
     
  9. Nige

    Nige Senior Member

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    I read it as the slide travelled further than they anticipated, not necesarily that it was bigger.

    Usually all the waste from an open pit mine is hauled off to waste dumps beyond the mine boundary. Imagine the mineral deposit as having the shape of a funnel (it was originally a volcano after all) and you chase it from the surface going deeper all the time. As you do the pit boundary at ground level gets wider and wider. I would be surprised if what slipped was "old spoil" unless the mine had moved from one pit to another and built on top of the former spoil dumps. it's not usual but is possible. Not knowing the geology of Kennecott in any detail I couldn't say if that's the case.

    I would point out that sloughs are part and parcel of open pit mines. I've been personally involved in one in Africa, seen the photos of Freeport in Indonesia, and now seen the photos of this one. All of them involved the movement of major league amounts of material (10+ million tonnes minimum). It's part and parcel of open pit mining. As one mine planning engineer once told me, the perfect mine plan for an open pit is after however many years of mine life that it has, the pit walls collapse just as the last truckload of ore leaves the pit. It's going back to the "funnel" I mentioned before, as you go deeper more waste has to be removed so you steepen up the walls of the pit as much as possible in order to reduce the amount of waste that has to be moved and so keep total costs down. The result of this is (to paraphrase Kevin Costner) - "Some days you win, some days you lose, some days it rains" .............
     
  10. alco

    alco Senior Member

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    Nige, I was told the reason for the extra travel distance was that the volume that came down was well in excess of double what they expected.
     
  11. Shenandoah

    Shenandoah Well-Known Member

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    Studies of major landslides have shown that in extreme circumstances the travel can be up to 20 times the height of the slide. The reason given is that as the rubble moves over the ground it can create a low friction boundary allowing the rubble to maintain its' momentum and energy. The rubble takes on what could be described as fluid characteristics as opposed to its' former solid characteristics and hence the flow. Had there not been an opposing wall to stop the flow that slide would have covered a lot more ground.
     
  12. alco

    alco Senior Member

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    I understand what you are saying, but what I was referring to, was the initial projections of the travel distance vs, the actual travel distance being considerable farther due to a much larger area having slid. With the initial projections, a considerably smaller area, and thus smaller height and smaller volume was projected to slide. Only in the last few days, did a larger area begin to slip. At this point it was too late, as there was no safe way to move the equipment further out of harms way. A decision was made to simply abandon what could not be safely moved and hope it weathered the storm, so to speak.

    Had the initially projected slide occurred, the equipment would have been out of harms way. Had the slippage not shown itself to be considerably larger in the later days before the actual slide occurred, there would likely have been operators still working on the equipment that was still in the pit, and this would have had an entirely different outcome.....and not a good one at that.
     
  13. Birken Vogt

    Birken Vogt Charter Member

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    I just don't understand how they could get close enough to the edge on top to be able to start taking it down, and not have it slough off and take a machine with it.
     
  14. alco

    alco Senior Member

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    I have a feeling they would start at an appropriate distance from the face, and bench their way down. If they were to mine out behind the existing vertical wall, they could drill a line of preshear holes and blast, allowing the material to slough down into the hole as they went.
     
  15. JDOFMEMI

    JDOFMEMI Senior Member

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    I think that is one of the reasons the volume to repair a slide is always more than expected. By the time you back off a safe distance, it really adds to the total to be removed.
    You would never approach anywhere near the recently failed edge.
     
  16. CAT793

    CAT793 Well-Known Member

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    Two Questions?
    Could they have used controlled Blasts to relieve the Load earlier and prevent the weight shift momentum?
    Is there a possibility they will can the OC and wombat the ore out?
     
  17. euclid

    euclid Senior Member

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    One point is cost and if this mine considers the value add to clean up and continue mining or just shutting down all together?
     
  18. Birken Vogt

    Birken Vogt Charter Member

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  19. 61BG

    61BG Well-Known Member

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    Cat 793 Maybe they could have shot it, But I wouldn't have wanted to be the driller...
     
  20. Oxbow

    Oxbow Senior Member

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    I am not sure, but having seen the area I believe that it was not a tailings pile but existing topography that was excavated.