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Eric N

Kvm's Vibrating Gold Concentrator

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Although this area of Alaska isn't near dry enough to consider drywashing except maybe in the May-early June dry season, I still find the concept interesting.

Several years ago I was introduced to the writings of Karl von Mueller and purchased a few of his booklets. One eluded me though. I did find one copy for sale for $85, but that was too rich for me.

I tried for several years to obtain one through the interlibrary loan program and just a few days ago, "Vibrating Gold Concentrators" was awaiting me at the local library.

So what is the scoop?

It is a sluice box with 1" high riffles spaced 4" apart. The sluice is mounted on a rigid frame with springs and has a vibrating sander mounted solid to the underside of the sluice. The sluice is 10" wide and 30" long. It has a tilted feed apron and a hopper is reccomended. The big issue is classification to 1/4"-.

The riffles are tilted toward the feed and must be sealed to the bed and the sides of the sluice. No bedding is required.

Feed should be enough to keep a steady sub-inch flow over the riffles.

The concentrator supposedly can be used wet if the material is slurried.

The vibrating gold concentrator is supposedly far less dusty and traps fine gold far better than standard drywashers.

Scaling up is possible and requires a larger vibrating mechanism.

So what do I think?

Were I in an area conducive to drywashing, I would sure give it a try. The ability to dialate the material between the riffles is exactly the same mechanism that make material exchange possible in traditional sluice boxes. Couple that with no dust being pushed upward means smaller gold will remain just upstream from the riffles.

In the book there was one problem pointed out with the design.

Sluice clean-out was slow and difficult.

Perhaps a battery powered vacuum would do the trick.

The copyright date was 1980, so perhaps "Dustbusters" weren't ubiquitious as yet.

I'm glad I didn't buy the copy for $85. But it is interesting.

Much of the booklet is reports from those who were using it and its variants as well as KvM's personal opinions on drywashing, design ideas and gold in general.

Any questions. Just ask as I have a couple more weeks before it goes back to the library.


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The thought I have on this is that the air in a dry washer really does help classify the material. In stuff with a lot of clay, vibration only would have a tough time getting the gold to settle to the bottom. The blowing air actually gets rid of some of the clay by blowing it into the air, allowing heavier, larger particles to settle.

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I haven't built or tried one out.

All my experience with placering is wet.

What I do understand is the neccesity of dialating the material so higher SG minerals can settle into the spaces produced. This is part of the problem I see nowadays.

My first vibratory sander was an old Black & Decker with a cast aluminum body. The viration was slow and lengthier than my current sanders.

Imagine a vibratory classifier where the vibration is measured in thousands of rpms and stroke is measured in millimeters. I would argue that this would be pretty ineffective. Same goes for modern vibratory sanders in a vibrating gold concentrator application. I think the stroke length and rpms have to be longer and slower to get the desired effect.

Now dialating the material is dialating. The mechanism doesn't matter as long as it isn't so extreme that it throws the material out of the container.

KvM claims that the mechanism recovers a larger percentage of the small gold. From wet placering, I know small gold pays the bills (in my area it is all there is, both small gold and small bills).

I know from experience that any turbulence tends to keep small low SG material in suspension. Both puffers and blowers do the same to the extreme. With NO experience in dry-washing beyond some dry panning, I wonder how much small gold goes along on the ride with the clay?

I've only read the booklet a couple times, but I'm gonna read it some more. Please understand, I'm not espousing this design for anything more than needing further testing. As the design is dirt cheap to build, a person could cobber one together over a week-end and test it at home in a closed circuit with flattened lead shot or some of their hard-won gold. Perhaps better drive mechanisms would be like the old Keene Hydromatic Jig or off-set weights on a shaft mounted in vertical and/or horizontal or ... well there are folks out there with far more ideas of my own. Whatever method tried, I would reccomend that the motor not direct drive the mechanism to minimize stresses on the engine bearings. Use rubber via belt or a 3-piece flx coupling.

Maybe the design earned a well deserve death? Maybe, like many designs, it just failed to attract a critical mass of adherents to make it a popular design. Perhaps in the grand scheme of things a magazine article would be warranted, Karl von Mueller's "Vibrating Gold Comcentrators" re-examined. The booklet will be going back to the Arthur Johnson Memorial Library in Raton NM in a couple weeks. And a big thank you to the librarians of the country for the Inter-Library Loan system.


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Here's a link to a product that was at the ICMJ Mining Summit earlier this year.  It's powered by an industrial vibration device that really provides some energy. 




It looks to me like it has some real potential.  Cleanouts appeared very easy, the riffle tray  pivots forward and the collected material can be dumped into a bucket for panning or other final processing. 




I held off from buying one mainly because I wanted to wait awhile and see more results and real world reviews.

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Admittedly it is an interesting design, but it deviates from KvM's design more than just a bit.

1. The design attempts to shake the stand as well as the sluice.

Why? Does shaking the stand increase productivity?

KvM's design puts the sluice on springs to avoid shaking the entire machine.

2. The stand makes rocking to classify possible.

Why? Is it neccessary to rock it in order to get effective classification?

If a person is rocking the machine, they aren't feeding it.

3. What possible reason exists for feeding the sluice with rocks up to baseball size as presented in the video?

Think about it for a minute. Vibration requires energy. The larger the material, the greater the energy requirement to shake it. If it ain't potentially gold, why run it through the sluice?

I noted that the video stated 1.5 minutes per half-full 4 gallon bucket using the F-3.

Yet the web page stated up to 18 buckets per hour for the F-3.

60 minutes divided by 1.5 minutes = 40 buckets

So 40 X 2 gallons per bucket = 80 gallons.

202 gallons per cubic yard

Swell for insitu dirt/gravel is 20-30%

Therefore 202 gallons X 125% = 252 gallons in the buckets.

252 divided by the 2 gallons from the video = 126 buckets

126 divided by 18 buckets per hour = 7 hours per cubic yard

But of course, you have to take time to fill the buckets, transport them and then feed the machine.

I won't go into the common problem with most all small recovery equipment beyond mentioning it.

The higher you have to lift the material to the hopper, the greater the energy output you have to expend to feed it. Power = weight lifted to a height within a period of time. Lift an equivalent amount of weight half as high and expend half as much energy.

Then there is the question of 20 hours on a battery.

Perhaps, but lead-acid batteries don't last long when used to fully discharged.

Then the up to 5 years use for the battery is doubtful unless it is used only on week-ends, well maintained and more recreationally than for production.

I have no doubt the F-3 is well made.

I don't see this as a device for production.

Just my opinion but if you feed a recovery device with a bucket, it just ain't production.

Ergo advertising feed rate by buckets means recreational useage.

It really is all about the physical laws of the universe and math.

I'm not suggesting KvM's design as the paragon of efficiency. I just think it is interesting.


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Excellent post, Eric,


Probably one of the more relevant "physical laws of the universe" has to do with the apple falling out of a tree and related laws of momentum and conservation of energy.


Considering the magical properties of gold - primarily it's extraordinary density, changes in the direction of movement of a gravitational extractive process that has the objective to separate the gold from the lesser dense products has to be closely studied and understood.


Apples falling out of trees are pretty well understood! Gold falling through a surrounding slurry in a sluice is similar but slightly more complex. The physical laws of the universe still apply. The many possible ways of vibrating introduce an almost infinite possibility of stroke, direction and acceleration.


An orbital sander that is truly orbital (circular) has questionable effect on gold. So, the question is what is the result of moving the sluice in an orbital direction with constant acceleration? Horizontal? Vertical? at 43 degrees azimuth and 27 degrees pitch?


Deister concentrating tables use an eccentric arm and a lift motion combined with horizontal stroke. The gold moves with each stroke. There are designs based on the physics of mass and motion that make sense and there are designs that just vibrate the gold or the sluice and have questionable "net effect" on recovery.


- Geowizard 

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