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overtheedge
22:11:54 Tue
Feb 1 2011

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Re: Quicksand Concentrator?

Sometimes a guy just has to shoot off his mouth. My turn I guess.

Forget all this VIV stuff. It is a red herring. Use the KISS analysis. What is vibration? Movement, nothing else. When you inject water into sand, what happens to the sand in front of the injector? It moves. Once it moves, it has kinetic energy and won't stop till it impacts against something else. Newtonian physics. The impact transfers some of the first particles kinetic energy to the impacted particle and so on. A veritable chain reaction. At the top of the column, we have the upper limit of the water table. Anything rising to the top is only wetted on the bottom and therefore the surface is dewatered compared to lower in the column.

I see a few aspects of the design that are critical for predicted operation.

1. Water pressure and volume must be completely adjustable.
2. The water injector must be sized so that the water from the injection ports must carry sand to the inner wall of the outer pipe.

I would bet that #1 and #2 work together; bigger gap between inner and outer pipes, more volume and maybe pressure.

  
Traveller11
17:40:37 Sat
Feb 5 2011

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Re: Quicksand Concentrator?

OTE

I have read your post several times and, after much consideration, I have come to the conclusion that your "KISS" analysis is likely closer to explaining the dynamics of the Quicksand Concentrator than anything we have come up with so far.

It makes perfect sense when one thinks of the water impacting each particle of sand and rebounding. Also, as the flow of water is lateral, each channel of water opened up likely closes a millisecond later from loose material above collapsing onto it; further compounding and enhancing the chain reaction you spoke of.

I wrote an e-mail to the company that manufactures the Q.C. to ask how progress was coming on larger versions of this concentrator. To my surprise, the answer I received stated there were no plans to develop larger Quicksand Concentrators and never had been. I found this rather odd, as I clearly recall the inventor telling me, over the telephone, that a larger concentrator was currently being tested.

This concentrator, in my opinion, needs to go to a larger size if only to make it possible to streamline the feed system. As you stated, it is likely essential that the water injection make it all the way to the outer wall of the concentrator. This may present a problem on a larger concentrator as the square surface of a circle grows exponentially the further one goes from the centre and a single injector pipe may be inadequate. I am going to experiment with a cut off five gallon pail. I think a single, perforated 3/4" pipe, fed from above and suspended from a frame on the rim of the bucket and standing vertically to the bottom of the bucket, will tell us very quickly if liquefaction is taking place all over the bucket or only in a limited central core. The injector streams might also make it to the outside wall but leave great sections of unliquefied sand on the outside wall between the points where the four injector streams contact the outside wall.

I hope a single injector pipe is adequate as it will make construction and cleanup of this concentrator very simple. However, I do see the distinct possibility of four (or more) vertical injector pipes, in a well spaced pattern, as being necessary to assure the flow from the injectors reaches all parts of the concentrator.

Regards
Bob
[1 edits; Last edit by Traveller11 at 17:41:52 Sat Feb 5 2011]

  
BillA
19:57:22 Sat
Feb 5 2011

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Re: Quicksand Concentrator?

Bob
at the risk of sounding like a bore, I'll repeat what I've posted

just start making some e-tubes, then you'll not have to speculate; YOU will observe and have facts to work with

there are several threads on this forum where I described my observations in some detail, and I trust you have googled "fluidized bed" down several hundred citations

one can center feed with a smaller tube/funnel at a defined/adjustable 'depth' and discharge waste from the periphery, a slurry will be required but steady-state operation w/o a process control loop is probably not possible (as I understand my test results, and I was pretty well instrumented - what I did for a living)

unfortunately the quest seems to be for something simple that works by itself
sorry, NFL

Bill

  
Traveller11
23:01:06 Tue
Feb 8 2011

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Re: Quicksand Concentrator?

Hey Bill
I'm not familiar with the vernacular of your trade. What exactly would a "process control loop" be defined as?
Bob

  
BillA
00:06:01 Wed
Feb 9 2011

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Re: Quicksand Concentrator?

Bob
In a nutshell, a process control loop (pcl) is a sensor whose 'reading' is translated into a control signal (+ or -) for a valve, pump, etc. These can be rather simple to very complex (Stuxnet worked on these).

What is being discussed is using a fluidized bed as a density separator. When the bed (e-tube, Keene jig, etc.) is charged and the pump started at some flow rate the bed will 'fluidize' and lift (water moving around the particles). It will be stable w/o localized boils only within a fairly limited flow rate with no addition of solids. If the tube/tub is full to overflowing then as solids are added (in low quantity) the bed will over flow the lighter materials while retaining the heavies.

The 'trick' to these devices is expanding the range of solids that can be fed w/o collapsing or boiling the bed (ideally from 0 to whatever). If excessive solids are fed the bed will collapse and may re-fluidize (or not) when the excess has been discharged - if it even will do so. Boiling will mix the materials and must be avoided.

If solids are injected into the bed w/o a corresponding amount of liquid to effect a similar density the bed will probably boil, but feeding the slurry may be difficult. A simple pcl in this case would vary the liquid flow rate in proportion to the solids feed rate (say a valve and a variable speed auger feed). My preference would be to measure the (apparent) density and adjust the liquid flow rate accordingly, this is rather more difficult from a hardware and software viewpoint.

Note that the Keene jig can be fed by shoveling w/o great problems, a nice machine even if underbuilt.

I can go on and on, but I still suggest you make a couple of e-tubes for the hands-on experience.

Bill
[1 edits; Last edit by BillA at 00:10:21 Wed Feb 9 2011]

  
overtheedge
05:41:11 Wed
Feb 9 2011

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Re: Quicksand Concentrator?

Bill, I think you nailed it.

The input slurry needs to be stratified by SG and the water/solids ratio needs to be roughly the same.

So the PCL must either adjust automatically or we find a work around. Any automatic adjustments require a feedback loop. Not too practical under field conditions.

The work around might be a relook at the E-tank such as the old Keene Hydromatic Jig.

When we consider that the E-tubes need sorting by size to operate within spec, and the Hydromatic had the option of classification by size or SG, we might have a low-tech route to pursue.

In a hydraulic sorting column, we can sort by size if we increase the water flow rate. Of course there are limits. Larger material needs vastly more flow to keep it in syuspension than smaller particles. Same principle as sluices. More and faster flow to get them stinkin rocks outa the sluice.

So we classify all the material before it enters the system. We have some sort of taps on the E-tank to bleed off each size fraction. Each fraction the goes to its own E-tube.

Simple principle, but difficult implementation. Here are the problems I see off the bat.

How do we draw off each size fraction without collapsing the column in the E-Tank? How do we maintain the dense slurry within each sized E-tube? How would we isolate the E-tube from the vibration of the E-tank? Do we have to isolate it?

Bill, gut instinct tells me you're right. Determining the possibility for the E-tubes to be part of a large throughput plant needs a willingness for someone to invest time and money to experiment.

Personally, I don't see scaling up as practical due to the distance between water manifold to outer shell being critical. However, if the distance element and flow rate needed to slightly dialate the bed could be determined and achieved, a larger E-tube would permit input in one quadrant and discharge of low SGs in the opposite quadrant.

We still face the classification and distribution problems.

Just my current thoughts.
----------------------------
All thoughts and opinions are solely the opinion of the author and don't neccessarily express those of our sponsor or this site. Author reserves the right to change his mind any time he takes a notion based upon new data or some fool idea. No implied warrantee expressed. Use at your own discretion and risk. Past performance is no indication of future performance. We now return you to your regularly scheduled programming.

  
BillA
07:14:11 Wed
Feb 9 2011

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Re: Quicksand Concentrator?

Joe, Bob, and OTE
There are many types of density separators, sluices, (true) jigs, and also fluidized beds can be setup to perform this task. The Keene hydromatic jig is in fact a fluidized bed with horizontal agitation.

Muley and I gave the Keene "jig" a brief workout to assess the operational characteristics. We used a Rosemount magnetic flowmeter (no line restriction and VERY accurate/repeatable) and separate valves for the tub sparger and mini-grizzly feed spray bar. Dual (isolated) pumps would have been better to minimize the interaction of varying the flow of a single leg. We were looking at how the bed was fluidized rather than the gold recovery per se.

Then we spent some time discussing what we thought was going on. For those not familiar with the Keene jig, see Robin's (Steppe) writeup on his site. Yes, a 1/4" waste rock will waltz right across the top of the bed. We liked the Keene jig (Muley has 2 of them) but felt it could stand some improvements, I think it is a hobby machine unsuited for even a single season's operation - and tore mine completely down to "rebuild" it to take a larger tub, more powerful engine, stronger agtitation linkage, sealed bearing wheels, etc. (Muley, feel free to correct me.)

While rebuilding the Kj, I bought a 30yr old NOS e-tube to play with and then built several more. But I had had a previous go at fluidized beds back in the 60s when I attempted to build one from an article describing one used as a hospital bed for burn victims. The bed was of glass micro-spheres and the air velocity/volume, temperature, and humidity were all controlled, with a sheet drawn tight over the top - for $6000. The rational was for minimal contact pressure, but a side effect was that one went almost immediatly into REM sleep w/o cycling so that 4hrs time = 8hrs sleep. I never got one built but I did learn about diffusion gratings.

The Kj has 4 horizontal parallel triangular spargers with the holes facing down with NO diffusion grating, while the e-tubes have horizontal spargers WITH a diffusion grating. It can be understood that the Kj will have a dead zone alongside and below the spargers while the e-tubes will not. This difference will affect how the devices start up and the relative concentration possible (the Kj concentrate will be more dilute due to the included dead zone material).

OTE's description of how the fluidized bed works is spot on, and as a density separator the heavies slowly work their way to the bottom. Mechanical agitation will greatly speed the process of separation. I initially used white quartz sand and hematite/magnetite black sand and they would separate into distinct phases perfectly -> unless their was a boil which very quickly would mix everything up. Robin has described "bums" which are the dewatered top surface areas around which the boils form.

The Kj has a tapered bottom with a 1 or 1 1/2" drain from which the concentrate can be removed at the end of a run, but it is noted that a considerable black sand bed must be built up before the Kj will be effective - I suspect due to the volume of the dead zone under the spargers. One of the e-tubes I made had a tapered diffusion screen with a center drain to draw the concentrate off, seemed to work ok.

When a fluidized bed 'lifts' its density is reduced AND its viscosity is reduced as well (one can stir the bed like porridge with a stick, the stick will just glide down into it). This change in density, or viscosity, could be instrumented to provide a process control input for continuous operation with a varying solids feed rate. None of this is trivial, but neither is it so delicate that it could not be installed on a skid mounted fluidized bed.

Don't like black sand with your gold ?
Not a problem, before startup charge the bed with an appropriate amount of crushed Tantalum Carbide! Sg 13.9, does not rust, and is magnetic. Black sand separation problems are a thing of the past.

Bill
[1 edits; Last edit by BillA at 07:16:35 Wed Feb 9 2011]

  
BillA
17:53:25 Wed
Feb 9 2011

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Re: Quicksand Concentrator?

Quote: overtheedge at 05:41:11 Wed Feb 9 2011

Bill, . . . . .

The input slurry needs to be stratified by SG and the water/solids ratio needs to be roughly the same.

So the PCL must either adjust automatically or we find a work around. Any automatic adjustments require a feedback loop. Not too practical under field conditions.

The work around might be a relook at the E-tank such as the old Keene Hydromatic Jig.

When we consider that the E-tubes need sorting by size to operate within spec, and the Hydromatic had the option of classification by size or SG, we might have a low-tech route to pursue.

In a hydraulic sorting column, we can sort by size if we increase the water flow rate. Of course there are limits. Larger material needs vastly more flow to keep it in syuspension than smaller particles. Same principle as sluices. More and faster flow to get them stinkin rocks outa the sluice.

So we classify all the material before it enters the system. We have some sort of taps on the E-tank to bleed off each size fraction. Each fraction the goes to its own E-tube.

Simple principle, but difficult implementation. Here are the problems I see off the bat.

How do we draw off each size fraction without collapsing the column in the E-Tank? How do we maintain the dense slurry within each sized E-tube? How would we isolate the E-tube from the vibration of the E-tank? Do we have to isolate it?

Bill, gut instinct tells me you're right. Determining the possibility for the E-tubes to be part of a large throughput plant needs a willingness for someone to invest time and money to experiment.

Personally, I don't see scaling up as practical due to the distance between water manifold to outer shell being critical. However, if the distance element and flow rate needed to slightly dialate the bed could be determined and achieved, a larger E-tube would permit input in one quadrant and discharge of low SGs in the opposite quadrant.

We still face the classification and distribution problems.

Just my current thoughts.
----------------------------
All thoughts and opinions are solely the opinion of the author and don't neccessarily express those of our sponsor or this site. Author reserves the right to change his mind any time he takes a notion based upon new data or some fool idea. No implied warrantee expressed. Use at your own discretion and risk. Past performance is no indication of future performance. We now return you to your regularly scheduled programming.


OTE
Lots of stuff here, will attempt to address more or less in order.

While I understand that an e-tube can be run with high flow to nominally sort by size PLUS sg, that is not my intent to describe at all (or utilize). I am considering operation only as a density separator, the physical preclassification would be such that the largest chunks passing would also 'float' on their particular phase within the e-tub/tank.

Picture a 3 phase density separator; top - quartz, waste rock, etc. (sg to ~5), overflowing over the top, middle - black sand and similar (sg ~ 5.4 - 12 ?), bottom crushed tantalum carbide and Au (sg 12+). Worth noting is that other heavy 'stuff' would be collected. Were it a 2 phase separator the Au would be with the black sand - which must be present in some thickness depending on the setup. In both cases the bottom phase can be tapped with some delicacy, tapping the center phase would require balancing the discharge with additional solids and liquid input to maintain the fluidized bed.

Based on my messing around with the Kj, I suspect that sizing to 1/4" might be ok, 3/16" pretty easily. I would presume that the upstream classification would have recovered the coarse gold enabling an even lower cutoff. The dwell time would probably define the minimum fineness recovered, and worth noting is that the material on the top of the Kj tub moves much much faster than the lower contents. -> A fineness vs depth vs velocity profile is needed.

Regarding e-tubes, e-tanks, and e-tubs; lots of differences seen between them. E-tubes will always have an edge effect around the periphery, to my mind this limits their utility to a lab device or some such. The inventor of the Kj made much of the specific slope of the sides for his e-tub (tank?). This is rather important and should be verified with a plexi model. Additionally the Kj should, in my opinion, be fitted with a diffusion grating to decrease the idle black sand or tantalum carbide; drainable of course.

The instrumentation would be sorted out once the configuration of the tub/tank is approximately defined. Not really too difficult as I believe it can be done with differential pressure sensors of the appropriate sensitivity (Rosemount, Foxboro, etc.). Use a Simens controller, lol. The industrial versions of this stuff are typically explosion proof, very robust - you can beat 'em with a chain. Find them on eBay for pennies on the $ (if one knows exactly what they want/need). Once proven, buy backups of everything, no biggie.

Bill

  
baub
03:40:16 Wed
Mar 7 2012

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Re: Quicksand Concentrator?

Worth bringing back. Anyone have any practice with this thing? How did it do? Any comparisons to the G-! or Gold Cube?

b

  
sluicebuilder
14:50:27 Wed
Mar 7 2012

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Re: Quicksand Concentrator?

I bought a QUICKSAND couple years ago, did alot of testing.found better results when classifing to 12 rather tha 8. also added a small finish sluice with vortex mat to the discharge of the unit(3' lg.)this caught some fine gold that discharged from the QUICKSAND, (very fine). ran it at the creek with 12 volt pump, did good job, but again had to classify to #12 to keep from building to much cons in chamber.feed rate was a factor in how well it removed lights and retained the good cons. mounted mine in a 5 gal.bucket, with discharge lip sticking through opening cut in the side. made a transsion from under discharge lip to my finish sluice. ran finish sluice into recirculating tub at a very steep angle to catch the fines.NOTE: carefull when stoping to clean out unit, cons can run back into the pump hose and get into pump.GOOD LITTLE UNIT.

  
dredgeguy
16:06:36 Fri
Apr 6 2012

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Re: Quicksand Concentrator?

There are more Quicksand Concentrators in larger sizes made by R.C.M.

They work on specific gravity and particle density.

Screening to 8 mesh works. The unit is suppose to have concentrates in the unit up to the white cap.

If you have 50 buckets you will always end up with a half a pan of cons left.

The Quicksand only actually works while material is being added to the system. Active transfer of material can only occur with new material to transfer.

After running the unit it is cleaned out by tipping it over and washing into a pan.

We then use magnets to get rid of more material and pan out the cup or two that is left.

Most people treat it way to gentle, We run a 5 gal bucket every 5-6 min. over a 1000 pounds and hour.

There are Quicksand Fluid Beds up to 55 gal size. The most popular are the quicksan gold chamber which runs 1/2" material, the Gold Sluice runs 1/4" material and the 24" x24" fluid bed for larger wash plants running about a 1 ton and hour each or more when set up modular config.

Hope this helps clarify.
Rick

  
jcazgoldchaser
00:16:58 Wed
Apr 11 2012

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Re: Quicksand Concentrator?

Good video on what goes on inside:
DSCF5372.flv

The quicksand commercial:
Find Gold with the Bucketdigger and Quicksand Concentrator

Other fluid bed methods:
Mini DIY Gold Fluid Bed Box
($10 solution)

Fluid bed gold recovery.wmv
($3 solution)

Fluid bed gold ore concentrator (Take 1)
($50 solution)

Looking for Gold - Episode 6 - Bazooka Gold Trap Sluice - Part 2
(experiment with a pseudo copy of the bazooka sluice)

fluid bed
(larger scale?)

UnderFlow Sluice vrs. Drop Riffel
(underflow separator, unless he's losing really fine gold, seems like the way to go)

  

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