Quicksand Concentrator?
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Seden
22:10:17 Sat
Sep 25 2010
Quicksand Concentrator?
Just found this little unit that sells for $60 made by RCM that is a concentrator. Uses "Vortex displacement with fluid cylinder field and an enriching chamber to get all the gold."

Any thoughts folks would be appreciated as I have a bad habit of being the first one to buy the latest new equipment only to lose my shirt trying to sell it on ebay (a couple thousand or more-ouch!). Here's the URL: http://www.gotnuggets.com/qucoforgo.html

Randy

dungbeetle
23:55:22 Sat
Sep 25 2010
Re: Quicksand Concentrator?
Looks good, well proven concept and for $60 the price isn't silly. I'd buy one, no probs.

chadjensen1
22:05:55 Sun
Sep 26 2010
Re: Quicksand Concentrator?
I played around with a similar concept. It moved alot of dirt and used minimal water. It had a lot of good points. The only thing was I used vibration and up flow instead of vortex and up flow. The only thing "Wrong" with my design was I didn't diffuse the water and so I got a fluid column in the middle of my pipe. I have been thinking of going back and refining my design. It was really pretty good. But for 60 bucks it may be worth it to buy this and play around.


Seden
22:52:39 Sun
Sep 26 2010
Re: Quicksand Concentrator?
So I guess it's basically an E-Tower huh? Yeah I've always wanted to play with one of those. Thanks for the input,

Randy

Greg_in_BC
15:47:46 Mon
Sep 27 2010
Re: Quicksand Concentrator?
It does look interesting and perhaps with the swirl would not pack the same as regular E towers?

Likely best to size feed to many cuts in order to get the best sorting action.

So with a design like this would the gold 'fall' to the middle of the bottom or go to the outside?
Greg

dredgeguy
18:18:31 Thu
Sep 30 2010
Re: Quicksand Concentrator?
The gold falls to the bottom and sits in 4 separate dead pressure areas. Enough gold will just fill the bottom up and start piling up.



49er_Mike
20:14:32 Thu
Sep 30 2010
Re: Quicksand Concentrator?
I received mine today...hope to try it out Saturday. Very simple design. Will be interesting to see how well it works.

Mike

Seden
23:10:05 Thu
Sep 30 2010
Re: Quicksand Concentrator?
Awesome Mike, I will look forward to hearing how well it separates the gold from the all the rest compared to the blue bowl or say a miller table.

Randy

Lonetree
22:31:45 Fri
Oct 8 2010
Re: Quicksand Concentrator?
Quote: 49er_Mike at 20:14:32 Thu Sep 30 2010

I received mine today...hope to try it out Saturday. Very simple design. Will be interesting to see how well it works.

Mike


Well Mike how did you make out with this?

49er_Mike
05:06:15 Sat
Oct 9 2010
Re: Quicksand Concentrator?
I have been so busy I haven't had a chance to try it yet. I talked to a guy here in Grants Pass that also just received one and he was very impressed. Left him with a "super con" with some black sands, still needed some cleaning. I am trying again for this weekend!

Lonetree
15:36:57 Mon
Oct 18 2010
Re: Quicksand Concentrator?
Curious on the outcome here.

chadjensen1
02:54:21 Tue
Oct 19 2010
Re: Quicksand Concentrator?
I got mine today and was impressed. It can be fed as fast as a sluice but uses minimal water(important here in the desert) I ran about a third of a bucket and got about what I am recovering classifying it down and using a finishing sluice. (all I have is my hose so I need something that works with a small amount of water) I am happy with the recovery and feed rate is awesome.

chad

Seden
04:20:13 Tue
Oct 19 2010
Re: Quicksand Concentrator?
Chad,

The guy's coming out with a 2 gal. and a 5 gal. version. Now we're talking about quick recovery.

Randy

Traveller11
18:08:05 Wed
Dec 29 2010
Re: Quicksand Concentrator?
I am almost convinced that this concentrator works on the principle of sand liquefaction; the same phenomenon that occurs during an earthquake in sandy soil that is saturated with water.
I have played with the idea of building a similar concentrator, along with many other people, but this unit is unique in several aspects. It is the only unit so far not to introduce the water entirely at the bottom of the unit in a manifold; rather, its distributor is a vertical 3/4" PVC pipe with four vertical rows of perforations from top to bottom that saturates the entire cylinder. Also, my concept, and everyone else's, would rely on some form of low speed vibration (mimicking an earthquake) to achieve liquefaction of the material in this unit.
How does he do it? If the inventor is achieving full liquefaction without need for applying power to a vibrator, I would say this man is literally miles beyond us. I just received the 4" model, have not been able to try it yet and eagerly am awaiting the debut of the 2 and 5 gallon models. And, as I was told by the inventor, it is possible to scale this concentrator up to any size. He may very well be about to change the world of placer mining.
Regards
Bob

mldave
15:28:32 Sat
Jan 1 2011
Re: Quicksand Concentrator?
Will this seperate the gold from sand that's the byproduct of a Keene type mill?

Steppegold
15:51:52 Sat
Jan 1 2011
Re: Quicksand Concentrator?
It sounds very promising indeed.

Its a potential BAT, and I'm looking forward to any independent tests and reports from Forum members. If soon, then I'd like to add it to the BAT Book.

If the device really does use minimal water, then its not likely to be an Elutriated Tower but a minature sludge tank - I call 'em E-tanks.

The best-known E-tank is the Keene Jig (its not a jig, its an E-tank) but there are a lot more. With that exception, the consensus is that E-tanks cannot work. I beg to differ as seen by earlier posts.

One feature of an E-tank is the ability to shuffle particles with minimal water, whereby low density particles rise very fast to the surface - even big pebbles, and high density particles rocket to the bottom. Neat.

Let's stick around to see the outcome.

cheers

Steppe

Traveller11
19:22:17 Sat
Jan 1 2011
Re: Quicksand Concentrator?
Steppegold
I believe the time has come to re-name elutriation tanks as the name is somewhat misleading, in this application, and can only lead to misunderstanding of the mechanics involved therein.
From Wikipedia:

Elutriation, also known as air classification, is a process for separating lighter particles from heavier ones using a vertically-directed stream of gas or liquid (usually upwards). This method is profoundly used for particles with size (>1μm). The smaller or lighter particles rise to the top (overflow) because their terminal velocities are lower than the velocity of the rising fluid. The terminal velocites of any particle in any media can be calculated using Stoke's Law if the particle Reynolds number is below .2.

This, of course, very well describes what is going on in an e-tower but does not define the mechanics of the Quicksand Concentrator at all.
This concentrator relies entirely upon the liquefaction of sand, as does the Keene Hydromatic Jig. With proper saturation of material and low speed horizontal vibrations, sand literally turns to liquid. Buoyant objects will float and denser items will sink, just as if they were in water. It is also the reason graveyards cannot be sited in low lying sandy ground prone to earthquakes, as coffins have been known to actually pop out of the ground during tremors.
The giveaway is that the makers of the Quicksand Concentrator require the operator to screen his material to 8 mesh before processing. This is approximately the upper limit of particle size in the phenomenon of soil liquefaction during eathquakes. Materials with larger percentages of larger particles (gravels) may liquefy under ideal circumstances, but not nearly as easily.
The key difference with the Quicksand Concentrator, when compared to the so-called sludge tanks, is how water is introduced. I believe this one feature shows the true genius of its inventor. Instead of a manifold at the bottom of the tank to introduce water, there is a single vertical pipe (3/4" PVC) with four vertical rows of perforations. I believe this avoids the dreaded channelling of water simply because if a channel opens, it is horizontal and there is a mass of saturated sand above it to collapse said channel.
Also, there is another thread on this site about Vortex Induced Vibration; the phenomenon of vibration induced by water flowing around objects in a stream. What if horizontal streams of water in a constantly collapsing medium, as in this concentrator, created these vortexes (and a resulting horizontal vibration) flowing around each and every particle of sand? This is what has puzzled me about this concentrator. It has all the ingredients for sand liquefaction (saturated -8 mesh sand) but lacks the horizontal oscillations to induce liquefaction. Could VIV explain this? If it does, could vertical rods, on a larger version of the Quicksand Concentrator, be placed in the flow from the perforations to induce even larger vibrations?
Regards
Bob

Steppegold
21:35:44 Sat
Jan 1 2011
Re: Quicksand Concentrator?
Hi Bob - good post.

You are right, the nomenclature for these devices is in a bit of a mess.

Like you, I have no problem for what are called Elutriation Towers (E-towers], in which the slurry is rather watery.

The name-problem arises with a group of devices sometimes called jigs (which they are not). They have in common the presence of a tank, containing slurry that is thick enough to be a sludge (i.e. not particularly runny, but not so stiff as to be a solid either). I have gathered up this rather little-known group of devices and badged them as Elutriated Sludge Tanks, or E-Tanks for short.

In view of your comments, it might be better to drop the world Elutriated, and simply call them Sludge Tanks.

The Quicksand Concentrator is still, probably, a Sludge Tank as it contains sludge. In my experience it requires a sludge to trigger a decent quicksand, whereas a slurry rarely can because it is too watery.

Hmm, regardless of how the water is introduced into the sludge, in my humble opinion its still elutriation if the water is introduced from inside or beneath the sludge.

In my experimental dabbling, it takes very little energy to trigger liquifaction of a sludge into a quicksand, and the energy can be introduced by a) vibration and/or b) lubrication and disturbance by water injection.

So, until there is more info on the Quicksand Concentrator invention, I still see it as being a Elutriated Sludge Tank.

What is your opinion on this?


Steppe

Traveller11
22:10:24 Sat
Jan 1 2011
Re: Quicksand Concentrator?
Steppe
As I am still puzzled by how the Quicksand Concentrator can induce liquefaction without vibration, would you please elaborate on your statement "...and the energy can be introduced by a) vibration and/or b) lubrication and disturbance by water injection."
I tend to think that b) is true in the case of the Quicksand Concentrator, but am having trouble grasping the mechanics. Do you think it is some kind of Vortex Induced Vibration, as I mentioned earlier? I am awaiting a reply to a post I made to the thread "Sluice vibrator powered by water flow". In it, a member named Juilanh discusses VIV and I am hoping he may shed some light on this matter.
Whatever the mechanics involved, I believe the inventor of the Q.C. is about to turn the world of fine gold recovery on its ear. I spoke with him and was told that the Q.C. is scaleable up to any size; even something fed by an excavator. He also stated that one of his customers grinds his black sand to 200 mesh, presumably to recover hidden values, and is able to recover 95% of the PM's with the Q.C.
For my purposes, a unit the size of a standard oil drum would be more than adequate; due to restraints on beach mining here. Whether one is marketed by the Q.C. people or we develop our own unit here, only time will tell.
Regards
Bob

Steppegold
22:57:11 Sat
Jan 1 2011
Re: Quicksand Concentrator?
Hi Bob,

The general belief is that quicksands need vibration to occur. In fact this need not be the case. All that is required is a density inversion. This occurs if either water is injected from below, or if the upper layer dewaters by settling, compaction etc.

Then the upper more watery sediment has a higher density than the lower watery sediment. Due to vibration or due to slight irregularities in the contact of the upper and lower layers, then the upper layer collapses downwards into convex down cells known to some geologists as - pardon the expression - bum structures. Between the bum structures erupt fludized dewatering structures, that can reach the sediment surface as sand/mud volcanoes. General collapse of the upper dense layer may take place.

Vortex Induced Vibration may play a role, I guess, but it is not necessary in general. However how the Quicksand Concentrator works I have not yet got any firm idea about.

Sorry to be a bit vague.

cheers

Steppe



Traveller11
03:26:30 Sun
Jan 2 2011
Re: Quicksand Concentrator?
Steppe
Your explanation seems to make quite a bit of sense and, with no visible means of vibrational induction on the Quicksand Concentrator, stands alone in explaining the successful liquefaction of material in this unit.
It also agrees with what I have researched about sand liquefaction during earthquakes. From what I have read, the vibrations on the X-Y plane tend to settle sand layers into denser masses. Water present in this sand gets squeezed and attempts to evacuate (sand volcanoes) but cannot evacuate quickly enough. The resulting rise in pressure (or pore pressure, as it is referred to) is key to liquefaction, and is aided by replacement of the evacuating water from other parts of the aquifer. It actually creates a thin jacket of water around each sand particle, isolating it from other sand particles, totally eliminating frictional resistance and lowering viscosity to nil.
Now, as you said, if water is introduced from below (or above), this may result in the same rise in pore pressure and achieve the identical liquefaction. It may very well be that the only reason water is injected laterally (although over the entire vertical depth) into the Q. C. is to eliminate the vertical channelling observed in many bottom fed sludge tanks and the resulting compaction.
As they say, the proof is in the pudding, and, by all reports, the Quicksand Concentrator is doing well; outside of the fact it is so small. I hope its inventor has the larger models on the market by spring.
Regards
Bob

Traveller11
04:47:43 Sun
Jan 2 2011
Re: Quicksand Concentrator?
Steppe
I just experienced a "wee epiphany" here, as a Scottish friend of mine is fond of saying.
Up to this point, I have been assuming that the Quicksand Concentrator, while in operation, exists in a constant state of liquefaction, as would a concentrator equipped with a source of lateral vibration. What if it exists, only in a state of saturation, with just the POTENTIAL for liquefaction?
I was looking for the source of vibration or disturbance; what if it is provided each time the operator dumps in a fresh batch of material, compacting the upper surface of what is already in the concentrator and raising pore pressure beneath it?
Also to be considered is the effect of overloading of the upper lateral streams of water by the incoming batch of material. This effect would quickly spread to the lower streams of water. Would the sudden overloading and interruption of these streams be able to create mini water hammers and resulting shock vibrations? As these streams are horizontal, their sudden interruption could give us the horizontal vibrations so glaringly absent from the Q. C.'s design.
Your thoughts on this, sir?
Regards
Bob

shaftsinkerawc
08:40:02 Sun
Jan 2 2011
Re: Quicksand Concentrator?
Looking at the photo it has a lot of water discharge. Have any of you that are testing it checked the GPM at the discharge chute? Running a 500 GPH pump should make the discharge around 8 1/3 gallons/minute. If I remember right the Keene Hydromatic called for about 3 GPM. Seems like that much upflow would flush the fine, flat, flaky's out of the unit?

Traveller11
10:21:55 Sun
Jan 2 2011
Re: Quicksand Concentrator?
shaftsinkerawc
The advice I received from the inventor, Rick Mahoney of RCM Enterprises, was to install a regulating valve on the inlet port and adjust the flow accordingly. I agree, some of the videos show a rather heavy discharge of water from this unit but I do not think they have been properly adjusted. I installed a 3/4" brass pipe coupling on the inlet pipe and a 3/4" laundry tap onto that. From there to my garden hose, I have a short washing machine hose with female garden fittings at each end. I have only experimented with mine in the backyard, and not with gold bearing sand (not visible gold anyways LOL), but I have found I can maintain a good fluidised bed without much in the way of water flow.
The only drawback, so far, is introducing large amounts of feed without losing a little bit out the tailings discharge spout. I am playing with mounting a feed hopper above it; likely a 10" diameter funnel with a spout cut back to a diameter wide enough to fit over the vertical 3/4" distributor pipe. To get an adequate flow of sand into the concentrator, it may be necessary to cut the spout off the funnel altogether and replace it with a short piece of 2" ABS or PVC. There is a 3/4" PVC cap on the top of the distributor pipe and it is 1 1/4" in diameter. The bottom of the cap is 2" below the upper rim of the concentrator and I would extend the 2" pipe down to this point.
If the funnel is filled with the -8 mesh material proscribed and a little of the water flow is diverted to a spray bar mounted on the funnel, I believe a good steady flow of sand will be introduced far enough below the tailings discharge point (2" below the rim) to put it into the main separation zone and avoid the loss of fine gold in the tailings stream. Subtracting 1 1/4" (diameter of PVC cap) from 2" (dia. of pipe from funnel) gives us a flow diameter of 3/4" but this is misleading. The flow of sand will be in the outer section of the 2" pipe. The area of the circle occupied by the cap in the centre of this flow is 1.23 square inches. The area of the inside of a 2" ABS pipe is 3.14 square inches. Subtracting, 3.14 - 1.23 = 1.91; well more than half the area of the 2" ABS pipe.
I believe this would be an adequate feed rate for this unit but, if a larger feed rate was desired, 2 1/2" pipe could be used in place of 2" pipe; or four smaller feed pipes (3/4"-1") from the feed hopper could introduce material around the distributor pipe instead of on top of it.
I hope that the two and five gallon versions of this concentrator, when introduced, have feed hoppers on them as standard equipment. Not only will it overcome the aforementioned problem, it will even out the feed rate and this is a good thing on any type of concentrator.
Regards
Bob

Steppegold
17:45:18 Sun
Jan 2 2011
Re: Quicksand Concentrator?
Hi Bob,

Here a doodle from the Gold Miners Book that may help. I drew it from many hundreds of field observations on Carboniferous and Triassic sediments in England, plus some rather tricky experiments on the intertidal silts of Morecambe Bay (where you have to run for your life when the tide rushes in and its not a good idea to be studying quicksand at the time!)...

The process often goes to completion, creating 'reverse grading' which is actually very common. However the process also often 'gets stuck' due to stiffness (viscosity) of the sediment inhibiting futher movement.

Here are my notes...

Expulsion of water content

Sediment dewatering

Once a layer of sediment has accumulated by particles settling, it may seem the settling is over. Not so! The layer often continues to settle further – a complex topic for research.

Final settling is achieved by a combination of expulsion of water and closer packing of the particles, both gravity-driven. These may seem to be “much the same thing” and indeed often occur at the same time. But the expulsion of water changes the semi-formed layer of settled sediment from being a virtual fluid to a semi-solid or plastic. With dewatering come many changes - viscosity (stiffness) increases, overall density increases, particle contact increases, and compaction takes place. Many are interdependent - the more dewatering, the more settling and therefore the more dewatering. The reduced water content stiffens resistance to reverting to a suspension.
Dewatering can affect the final settling and trapping of gold particles. How is this so? Dewatering and compaction are faster and more complete in the upper part of the settled sediment. So a uniform layer becomes internally stratified into a fluid-rich upper layer tending towards a semi-solid crust, and a lower layer that still retains much of the original fluid. As the ‘dewatering front’ progresses downwards, it is liable to stop! Why? The upper layer by dewatering faster has become rather impermeable or highly viscous - hardly surprising if the settled sediment has a wide mix of particle shapes and sizes and a high silt or clay content.

With dewatering halted and a stratified 2-layer created, a new set of forces can apply, often rather suddenly - even dramatically. The lower fluid-rich layer erupts up through the upper more dewatered layer. The mechanism for this is clear, as the dewatered upper layer is now RELATIVELY DENSE AND STIFF, whereas the lower layer by retaining much of the original fluid content also retains the original lower density and more moderate viscosity.

By this means, settled sediment is prone to stratify itself into a DENSE layer on top and a LIGHT layer beneath, resulting in density inversion. Being denser, the upper layer is prone to founder by plastic deformation with inelegantly but aptly termed ‘bum structures’ that balloon downwards while the lighter lower layer is pushed up by pressure differences to erupt.

The phenomenon is seen on a shore where fresh muddy/silty sand has been left by a receding tide. It can also be seen on a jig screen or sluice bed. On some shores, the process is dramatic and life-threatening if the density inversion destabilises the sediment into a dangerous quicksand. An erupting sand/silt/mud funnel may be a few millimetres across or big enough to be a ‘sand volcano’ or ‘mud volcano’. If the upper layer has dried and is crusty, then it may be breached by a dyke of erupting material.
If the process is gentle and steady, then gold particles, by virtue of high density, settle further down and so are at less risk of loss by scouring. Conversely fine quartz and clay minerals are liable to be carried upwards by plumes of rising slurry.

If the process is vigorous or spasmodic, then a surge of dewatering may suddenly carry upwards even dense particles of gold, and particularly fine gold.

If the upper layer dewaters and compacts, this impedes recovery of freshly-settled particles of gold. Being unable to sink down to safety, they rest on the hard-packed surface of the settled sediment and some will be lost by scouring, turbulence, surges in flow etc.

Measuring dewatering of settled sediment

The author has been unable to discover any published methods of measuring the dewatering of settled sediment in the context of gravitational recovery of gold particles.


Traveller11
05:58:03 Tue
Jan 11 2011
Re: Quicksand Concentrator?
Steppe
Awfully sorry I took so long to reply to your post. There is a lot of information in it and it has taken me a while to absorb it and sort it all out in my mind.
What you are describing with density inversion is similar (I think) to a phenomenon I have been watching for some time here. It may also explain the disappearance of gold in many parts of the beach placer here.
Could this density inversion take place on the sandy upper surface of a sloped beach? If this section of the beach was at the water's edge, it would mean that the beach material beneath this sandy section would be already saturated with water. Each incoming wave would saturate the upper sandy component, liquefying it. Lateral agitation is provided by the incoming and outgoing waves and the frictional resistance of the sand's surface. I have actually seen this upper layer almost inflating and deflating with water as each wave passes over it. I had never thought about sand liquefaction as being supplied with water from above before now, but it makes perfect sense when I think of it. I think I have even witnessed mini sand boils as waves recede.
The reason I mention all of this is the gold bearing black sand lenses deposited on beaches here. I once took two samples for assay from identical black sand deposits that were about 150 metres apart. One assay came back quite rich at .32 oz.Au/ton while the other came back with nothing at all in it for Au values. Both samples were taken at the tail end of a storm on a dropping tide with a good surf still washing the beach.
What I wonder is this; would the same forces that concentrate gold and black sand on this beach also cause a density inversion that would make gold deposited on one wave sink through liquefied sand on the next wave? If this were a steady process and the assay of .32 oz. Au/ton were only an indication of the last few waves, how much gold might have sunken to levels under the beach if there were several thousand waves in that particular storm??
Regards
Bob

Steppegold
06:36:13 Tue
Jan 11 2011
Re: Quicksand Concentrator?
Hi Bob - in short, yes.

But of course it gets quite complicated in reality.

In a layer of black sand, the gold should sink to the bottom if the sand is waterlogged and disturbed to become thixotropic e.g. by waves or by density inversion due to dewatering of upper layers.

However, and this is the tricky bit, if there are blond sands (quartz) around then in thixotropic conditions (=quicksand), the blonds are ejected upwards towards the surface. The small blonds should be winnowed away, while the slightly bigger blonds (yeah! - Ed) remain as a lag deposit ON TOP of the black sands.

There are of course too many variables in nature. But if you can make some spot checks then you might just find the signature of where a classic vertical sequence exists:
- blonds on top
- black sands below
- gold at or near the bottom of the black sand

If you can find part of the beach that is a DANGEROUS quicksand and has been so for say a decade, then every gold particle that trundled over it has had a very high chance of being swallowed to form over time a bit of a bonanza. In such a quicksand under water, gold sinks immediately, black sand sinks leisurely and blonds are flung out.

Of course the quicksand need not be dangerous. More prevalent would be a large patch of black sand with a spring beneath it on the beach, so being a little elutriated (aka water injected from below). Its then a natural elutriated Sludge Tank, and will throw out any blonds who dare to linger, and will swallow any gold REGARDLESS OF SIZE - nuggets or fine gold - as its all about the relative density of gold:blacksand:quartz causing fast sink : slow sink : thrown out.

Sometimes we all get too focussed on Settling Velocity (.e.g. Clarkson's excellent Yukon tests) and completely overlook that AFTER particles settle then its SINK-FLOAT time.

After particles settle, It Ain't Over Till Its Over.
Provided of course that the sediment is loose due to density inversion from dewatering; vibration due to earthquakes, waves, vehicles or ducks; or elutriation by water from sub-beach springs.

That's the theory....

And causing large particles to rise up - this time regardless of density - is KINETIC SIEVING. Here are my notes regarding kinetic sieving in sluices, but its also visible on the swash zone of a beach (don't sit on dry sand, but lie full-length in the swash zone to see it in action!):

"Look at how steep the settled sand is in a riffle, and how these ‘cliffs’ collapse by mass movement at shut-down. It seems plausible that even while the vortex is operating, the steepness of the walls will trigger ‘thin film avalanches’ continuously or intermittently. Such avalanches are common in grain silos and sand clocks and involve only the superficial single layer of particles slipping downslope (or plausibly upslope in a strong vortex). When in motion, any small particle drops down the first big gap it tries to cross and so falls into the layer below. Welcome to the bizarre world of kinetic sieving! Small particles fall down gaps rather than burrowing down. It is common for gold to be tiny compared to magnetite due to ‘hydraulic equivalence’. This kinetic sieving stimulated by thin film avalanches merits study. It implies that a ‘wobbly’ vortex might trigger repeated thin layer avalanches, in which case kinetic sieving could be a key mechanism for trapping gold.

That's enough for one post.

Steppe



BillA
17:23:08 Tue
Jan 11 2011
Re: Quicksand Concentrator?
Steppe, not sure this is worthwhile - but here it is. I am NOT commenting on the subject device of this thread as I do not have one. I have however built 3 e-tubes and understand a bit about their function. And of course I have a Keene "jig".

It is one thing to fluidize a cylindrical tube, and something totally different to fluidize a square or rectangular bed. But in any case fluidized bed technology is well known and widely utilized (think coal benificiation, really super high tonnage).

When a bed fluidizes (for all the reasons described above) it's apparent density will decrease, and this is the characteristic utilized for process control of the upwelling flow rate. For a continuous feed system the liquid flow rate will be adjusted for the solids feed rate. Unless the feed is very very constant there will not be a single flow rate that can be set and then ignored. Forget batch/slug feeding, I do not believe any fluidized bed will be reliable with such feeding.

An alternate process control would be to utilize the rheology of the bed, too stiff = more fluid, too thin = less. Doable, but not trivial. Several shade tree approaches, but the loop must be tight enough to prevent localized boiling. Quite tricky.

In a tube, an effective sparger will keep the particles (in a cone above it) in movement - but there will be no movement to the sides and below the sparger, -> why the Keene oscillation is so important. So in a tube the heavies will sit on top of the dead zone alongside and below the sparger. This will add significant waste to the concentrates. For this reason a diffusion grating is placed above the sparger. (I made one in a cone with a center drain, seemed like it would work.)

Anyone interested in this should make a e-tube from any tallish clear plastic tube (one was from a big animal cracker jar), add a PVC tube with holes pointing downwards, and several layers of fine ss and nylon screen as the diffusion grating. Get a good flowmeter and a micrometer needle valve and many things become clear.

Bill

Steppegold
18:29:21 Tue
Jan 11 2011
Re: Quicksand Concentrator?
Hi Bill - great post, very helpful and much appreciated.

Frankly at this moment I don't know what class of device this 'Quicksand Concentrator' really is. As you know, there are a who range of devices that it might be.

For sure, there are 2 main types (ore extremes), at least that is my opinion:
1 - VERY dilute watery slurry E-TOWERS, in which a pea-sized piece of quartz will fall rapidly to the bottom, being controlled by Settling Velocity in a liquid medium.

2 - VERY stiff sludge E-TANKS, in which a pea-sized piece of quartz can NEVER reach the bottom, due to the elimination of the Settling Velocity 'regime' by a Buoyancy 'regime', in which the quartz is so buoyant it is ejected. The sink-float effect is due to the black sands having become concentrated enough to repel the quartz. To get this type of device working it may be useful to add black sand at the beginning in order to charge it up.

Just now I'm tinkering with the Chapter on E-towers of the book-thats-still-not-finished-but-it-is-this-week. So your post is very timely. In revising the text, I've added what for me is new stuff, about 2 designs, fully tested by MIRL, one for a low-energy narrow E-tower suitable for catching fine gold, and the second being a higher energy wide E-tower that ejects rocks to leave cassiterite (tin ore) chunks as saleable concentrate.

Overall, the advice I've been hearing from people is that for a watery E-tower it is important to keep the diameter of the tube narrow. But for a stiffish E-TANK (as I like to call them) the container can be much bigger (as in nature, and as with Duke's E-tank) but yes there are all sorts of challenges in getting such to work smoothly.

Got to go, got to keep writing and doodling.

cheers

Steppe






shaftsinkerawc
20:43:25 Tue
Feb 1 2011
Re: Quicksand Concentrator?
Traveller11 or anyone else!

Has anyone done any testing that they are willing to share? Traveller11, did you get your feed hopper idea finished and tested? Have a great day.

overtheedge
22:11:54 Tue
Feb 1 2011
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
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

BillA
19:57:22 Sat
Feb 5 2011
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
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
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

overtheedge
05:41:11 Wed
Feb 9 2011
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
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

BillA
17:53:25 Wed
Feb 9 2011
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
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
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
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
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)




Quicksand Concentrator?
http://bb.bbboy.net/alaskagoldforum-viewthread?forum=2&thread=27
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