Jan 8 2010
I posted a thread a couple of years back about the washplant we brought up from Arizona to our California digs. Figure everyone's pretty much bored to tears by now with winter set in, so if you have twenty minutes to spare, I found these two vids that Vince posted to youtube. Kinda fun to watch someone finding good gold. We haven't had a chance to run yet, but we've put in a bunch of time making modifications. If all goes well, I'll have some new vids after next April and hopefully some gold to show.
Jan 9 2010
Jan 11 2010
As I watched,I noticed a lot of vibration action in the water.Have you tried it both with and without vibration?If you've tried it without,how did recovery compare? Is there fine gold to be recovered there?
Does your vibration come from the bottom up in the sluice or is it from the sides?(side to side shaking) It must be an effort to keep the suspended
mud from packing by fluidizing.Is that correct?
Jan 11 2010
I believe the rough water in the sluice is caused by the riffle set used and the general lack of water. The sluice is 20" wide and 12' long and all wash water was provided by a 5HP Briggs from a very small seasonal creek. I doubt if it provided 200gpm and the riffles were fairly crude. There was some flattened expanded on carpet underneath a few inverted Hungarian riffles that were on something like 10" spacing. By inverted, I mean that the normal riffle overhang was turned over and laid flat on the carpet and the riffle that remained was nothing but a sloped flatbar riffle. I can't imagine a worse system,...............too little water with cemented gravel running over a smooth carpet with what I consider a 'reject' riffle system. Rather than gathering up the heavies, the angled riffles toss them back up into the current.
We've doubled up on the water flow and replaced the riffle system with MM under heavy expanded with just a couple of feet of 1" angle at the discharge end. The material we plan to run will have mostly fine gold in it since we're only planning to run the overburden from the bar and the lower pay layer will be dredged. Depending on how things go, we may or may not 'buzz' the sluicebox. All it would take to deactivate that feature would be the removal of the belt drive.
Jan 11 2010
I would be willing to bet that with the small amount of water you showed going through it, you must have lost gold.
What you had going over the riffles looked like a "tumbling effect" rather than a swirl, which is what it takes to hold heavies.
It would be interesting to run the tailings and see what was lost if you still have access to them.
How does it run now with the modifications you did?
Jan 11 2010
All in all, they DID recover a pound of gold from the 200yd that they did run, so if my figures are close to correct, Vince has got at least 36oz left in his driveway!
If things go according to plan(something 'things' are not known for doing), I'll be able to report better performance in May after we've had a chance to work our gravel for awhile. The plant's ready to get back in the game with just a few hose connections and a pile of willing gravel.
Jan 12 2010
Jan 13 2010
Watching the action in the sluice it appears water is shooting straight up from the bed in finger shapes.This would give the impression that a vibration is forcing it to do so.As it does,i lifts the gold with it and leaves it susceptible to the oncoming flow...which moves the nugget along to the next diamond.The gold was not up against the upper apex of the diamond but rather wherever it happened to land.You could say this happened at shutdown but that seemed to be where they were during actual operation.Another man and I watched this take place and he commented on it.
If it were my rig,I think I'd rerun material that was sluiced.I would like to think it would have less silt in it so I could observe the action.i'd have enough so i could run at ordinary flow rate or even meavier flow as jim suggested.I'd add lead shot some smashed flat while others were left rounded.Maybe paint them yellow so they would show up in the flow.Run it both with and without vibration.
Whatever it takes,that plant could be made to work much better without much effort I'd bet.You could probably even salvage those riffles if they didn't work.I'm guessing they could be drilled along the length and have angled stock bolted or even tacked on.Witgh bolting you'd be free to try various shapes.
I've seen people wrestling with sluice bedding variations.As I see it,if a gold specimen peaks above the mesh weave,the flow can take it and make it migrate.This is why, both on the beach and back in the creeks,expanded is best followed by a short section of riffles.Bouncing the specimen around in the mesh exacerbates the problem.
I yield the mike.
Jan 13 2010
I also don't think an estimated 50% loss once the gravel got to the shaker plant is out of line. The best sluices running are only in the mid to upper 90's in recovery and there are many that perform down in the 60's and 70's, especially if they're running with minimal water. I suspect they're also losing a fair amount before the sluice even comes into play. If you look at the beginning of the vids, you can see just how poorly washed the oversize is as it's coming off the screens and discharging over the conveyor. That type of cemented material really needs a good scrubbing in a trommel. The shaker screen doesn't work very well unless the gravel is clean washing. Actually, that caliche probably needs a crusher to get above 90% recovery no matter what plant is being used.
Here's the before,.......
And after modification,.................
Old carpet was indoor/outdoor. New carpet is backed 3/8 miners moss.
Jan 16 2010
Jan 16 2010
I have armour weave in my 4" ProMack dredge. This stuff is not armour weave.
Armour weave is easy to identify; It is made of a sheet of steel with the "eyebrow" riffles punched in it. This means that the steel sheet is still there and can be easily seen.
So basically you would see a sheet of steel with the riffles punched out. It would not be like a large piece of expanded.
Apr 28 2011