I received yesterday and have not heard any more. They are expecting it to slide today or tomorrow It’s been moving 3 FT per day for the last week.
YIKES!! I guess everything with copper in it is going up 500%
I do not know if this is a old pit on mine site or not, waiting to hear back from my friend there.
It's not so unusual. I can recall major pit wall sloughs at Bingham Canyon and Freeport Grasberg, and likely hundreds of minor ones over the years. Mine designers try to improve pit profitability (less overburden to remove per tonne of ore) by steepening the pit walls almost to the point of slope failure. Sometimes nature comes back and bites them. The Bingham Canyon failure was captured on video. https://www.mining.com/bingham-canyon-mine-slope-failure-37216/ The Freeport one is not so well documented on the web because of Freeport McMoran's fixation with secrecy. Photos do exist though, IIRC the material that sloughed at Grasberg was of something of the order of 50 million tonnes. Doubtful. All the other producers will lick their lips and up production.
Not a good time for them . This is the same mine that had the jack failure on the shovel they were undecking isnt it ?
Yes it is, the mine has brought or getting a third party in to do a investigation.
The article you shared cites a HEF thread from 2013 as part of their sources. It cites this thread: HeavyEquipmentForums
As off 8:25 pm my time the big slide has not happened yet. They expect it tonight or tomorrow as movement was 2.5 meters or 7FT today. The circle section in Red is the slide area.
A bit of research reveals that both open pits at the Highland Valley operation have been suffering slope stability issues since the late 1970s, so I will hazard a guess that the situation is not going to be new to them. From a report that's over 10 years old......... https://www.tandfonline.com/doi/abs/10.1080/1389526042000263324?journalCode=nsme19
Partial slide at Highland Valley I understand there is or could be much more to slide yet.
The 2003 (I think) slough at Freeport Grasberg. About 50 million tonnes came down IIRC.
To give a better idea of the scale of what came down the bottom RH corner of the 2nd photo and the 3rd photo show parts of the same area. That's a 793 truck and I think a P&H 4100 shovel partly buried.
looking at how it flowed around the 4100, that stuff is fairly fine and fluid. Recovery must have been a nightmare if it was done at all on those pieces.
Pretty much everything that was "peripherally hit" was recovered and put back to work AFAIK. Not sure exactly how much machinery was completely buried under the slough. From memory it wasn't like Highland Valley where there is/was plenty of advance warning that the slough was coming giving time to evacuate machinery & personnel from the affected area.
Couple of interesting videos from Bingham Canyon. First one if I'd been the driller who put that hole pattern in I'd have been crapping myself thinking that my drill could have been on top of that lot..!! 2nd one is a time lapse of the 9-month process to dig through the bottom end of the slough and re-establish the haul road down to the bottom of the pit.
Wow. Sounds like the makings of a great episode of "Seconds from Disaster"
"driller puts a bunch of holes in to shoot and excavate" Mother nature says " never mind, I got you bro "
Always thought of these open pits as solid rock excavations . I would have never expected this kind of slope failure. I remember many years ago going the bottom of the pit at Utah Mines /Island Copper ,i believe they were almost 1400 feet below sea level,with the waters of Rupert Arm lapping at one side of the mine. If id seen this i would have never gone down there.
I've spent a fair amount of time in shovel pits. There was a rule that you had to be a certain distance from the working face. I want to say it was 2x the face but I can't remember. Haven't been in a mine in about 5 years.
To quote my comment on the other linked thread about the Kennecott pit wall failure...... "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" .............
Yeah, but there it rains rocks!
Same is true in the pesky small clay pits here. Get to a point of severity of angle and even rock will fluidize. Eventually the pit walls slide to a softer slope and becomes less a issue.
it's the angle of repose. What mother nature seeks in a given material.
I can not guess how many tones of material fell in the small slide but I remember in the early 70's at Kaiser I was on a D-9 and waste dumps are always moving and I was putting a ne lift on and a 200 ton truck would dump and that is not a huge amount of rock when you are putting a 10 ft lift on a waste dump
^ I had 4 50 ton terex trucks bringing me rock at Cowlitz falls, I had a 9L to push and it was maybe push push push and wait for the next truck on a 45 minute round. Hard to stay awake and the rotten rock would not tolerate a bunch of massaging. We were building that little island in the lake here from rock taken from the dam cut. https://goo.gl/maps/RtXZhDWuG2vrYqZX8
We used 1.5 times the bench height but basically the same thing. In really unstable areas Mine Ops would build a berm maybe 5m away from the toe of the bench to (hopefully) catch any stray rocks that came crashing down.
I don't know a ton about freeport Indo though did work for freeport for a while just as they started going underground block and cave in Indo. We'd get news articles and updates about Indo and I believe they went to almost all remote muckers ran on the surface pulling from the draw points because mud rushes out the draw points were so common. Is the ground in Indo just that loose and unstable?
Christy Minerals owns most of the clay pits here, has independents work those pits, have seen or heard there are changes coming to MSA Rules on depth to wall angle to bench width and height requirements at least on these mines.
Just received a text from a friend, the slide in the pit has not moved any more and they are going to open the pit again.
Just a couple of quick notes to help add to the info given. There are actually 5 pits at Highland Valley. 3 of which are currently active. The Valley pit was the only put affected by the slide, and the other 2 remained in operation. The Valley pit is the main pit though, so it was a considerable slowdown for them. The Freeport shovel is actually a 2800 or smaller. You can tell by looking at the back of the house roof. The 2800s and down used to have the raised rear section visible across the rear of the house roof. The 4100s have never had that feature. The two slides pictured at Bingham Canyon were actually separate events on different sides of the pit. The slide that was shown beneath the drill pattern was a second slide in 2021, years after the large one that was featured in the time lapse video that happened in 2013. Not trying to step on toes, just help expand the information presented.
I heard that a few days ago Highland valley had a 10 bench slide come down. Shovel in pit had rocks over top of tracks. No pictures as my contact is on holidays.
Are seeing typical fractured rock degradation on older bench profiles here. Highway cuts, deeper quarries. Extensive site set backs. When performed the original blastings’ the rock shatters further into wall, blaster I know noted such, over time freeze thaw fractures deeper and the walls fail, he suggested to the Highways group engineers here to revisit benches at least biannually to validate that extension of fracture for remediation. MSA is after miners here to extend benching further back as have had narrow escape events in the clay pits.