Post by
D797Bx on Jul 08, 2024 3:50pm
Leach Pad slope stabilization
I would think that they might consider something like a reverse cable logging technology setup to stabilize the pad and produce a secure slope. I wouldn’t want to be the person signing off on the explosives idea (kind of unlikely) or having people or expensive equipment anywhere near the pile or its base in its current condition.
Cable logging usually pulls the logs up the steep slope. In this case you want to pull the overhangs and bad slope angles gently down the slope, kind of like using a long handled snow rake on a winter roof, to get the material to the lower pad areas where it can be removed. The material is small sized and uniform and wants to go downhill if given some help, at least in the warm weather. You’re not going to catch on a boulder to dislodge in that pile and then have a lot more material moving than you want. Instead of the cable logging harness or grapple, you would use a small bucket or blade. The pull is downhill, so less resistance than dragging uphill. The working towers would be outside the pile on the top and bottom, so nothing in the danger zone.
I can’t think of a site where this system is currently needed, but here it may be able to be quickly set up using the conventional equipment used in logging.
Once material is downslope, it could pulled to the sides using standard long boom, small bucket draglines, where it could be placed elsewhere by truck/loader, which Victoria has. If the pile base width where the pulled down material is going to go to is too wide to make that effective, a cross pile reverse cable logging setup may be able to move the material to one side where it can be removed.
It might not be cheap or fast, but it should be buildable and safe.
Agreeing with a comment that’s already been made, the best place to put this saturated ore would be on another heap leach pad, but that was only in planning, and after this mess the approvals to build another one at this site are going to be hard work and take a while. Another option would be to pile it back in an ore pit. They are not mining for a while, and likely never will unless they get another heap leach or more expensive recovery system built, so the pit, as long as it’s kept properly dewatered, is unused space. Any cyanide leakage would be going back into future ore, so it might not be an issue as long as a mine reopening is possible.
The pile material would have to be removed right down to the liner, at least in the possible rotation area and lower sections, to visually check for rips. Even with sensors, is someone going to sign off on it if it hasn’t been fully checked, considering the vocal groups that don’t want it running anyway and politics being the knife fight that it is. Once the upper slopes are stabilized, cold weather might be their friend when the upper parts can freeze solid, or at least get a hard frozen cap, and it’s safer to clean down to the rubber in lower, maybe warm-weather supporting sections. Depends how soon they get started.
I’m not sure how safely feasible that idea is as I’ve only seen site pictures, but it’s out there.
The dozer in the pile can sit there until the pile is stabilized and the material around the dozer is removed. It’s not going to rot, and Victoria is not mining anyway. I saw someone mention it being a D11, but I saw previous pictures of a dozer marked D10t being used. I would think having a D11 would be a big cost overkill for an operation using 150 ton trucks.
As far as the water issues go, any open pits that I’ve been around have had dirty water ditch systems and clean water ditch systems on the lease. The dirty water ditches were not necessarily dirty, depending on the mine, but were within any working areas of the mine, so their flow was kept in the area and maybe had a mine operations use. It rains, snow melts, and the water buildup has to be controlled somehow. The clean water ditches were outside of any working or touched areas and flowed away from the mine, unless maybe the operation had a need for a water supply and was licenced to do so. Both ditch systems were subject to checks. Just what I’ve noticed; maybe this set up was different. My question would be if there are elevated levels of anything, is it in the dirty water system, which I wouldn’t be surprised at considering the tsunami they might have got when the saturated ore flow hit those small ponds that appeared to be in the lower valley, or in the clean water ditch system. Dirty water issues might be rapped knuckles; clean water issues might be a head.
Of course the local native group called for a mining halt. The leaders have to appease their members that didn’t like the mine anyway and probably didn’t have jobs there, and there’s an outside chance that there might be other problems. The mine is shutdown anyway, and will not be running for a while. Nothing changes with that action but see if their tune changes if it gets to a stage where the mine somehow could be restarted, if everyone is satisfied. That’s when their opinion is important.
Just my thoughts.