My Diy Fluid Bed Gold Trap Sluice

[Timberdoodle]

In my experiences with a fluid bed I've learned that it's a very good idea to have the jet's angled downward to keep the material fluidized and this also aids in creating a material loop which sends material passing the jet stream downward to the bottom before it returns upward based on it's SG. I believe if your not maintaining a constant exchange and fluidization of the material throughout the collection chamber then the space taken up by a layered bed of material creates a restriction and will cause higher flow velocity through the chamber and the result over time is similar to a riffle that's packed with black sand - loss of gold. It is the key difference between a true fluid bed sluice and other concepts.

 

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[Timberdoodle]

I believe Capt Nemo stated in his earlier post that he already solved the problem by angling the jets at 120 degrees to improve fluidization and thus liquefy the material.

Would adding some sort of vibration help in a sluice of any type - yes, it's been a proven method for well over a hundred years and helps gold penetrate layers of black sand.
If the level of liquification provided by vibration is strong enough to prevent the black sand from packing up then the goal has been achieved. If it is not, then the more black sand introduced builds and packs even tighter with vibration and reduces the ability of the gold to quickly settle into the black sand and it stays higher in the turbulent water column longer leading to potential scouring and losses.

Black sand buildup is an age old problem with most sluices and losses are directly increased over the time of a run as we all know. My question to KevininCO is whether he experienced packing up to a point where his finger test did not easily penetrate the layer of black sand? If he experience a "cake" of black sand then the fluid dynamics of the sluice are changing over the run time and capture rates are changing with them directly.

I'm not trying to bash a concept or sluice, I'm just trying to present a problem that exists in most equipment and may need to be addressed to improve long term performance. One thing I have found out working with fluid beds, over/under sluices, and submersibles - each change to improve an effect on capture rate or classification etc. has a counter-effect on another aspect of operation. It's getting them all dialed in to each other that's extremely difficult. As a fellow inventor I simply offer a word of advise - If you do not address each aspect of operation or limitation that is a problem that either yourself or people testing your equipment have found then unfortunately your customers are going to find it also. I see too many inventors talk themselves into believing that it's the customer who needs to change to meet the needs of the inventors design and not the inventor needing to change to the needs of the customer which is a sure recipe for ultimate failure.

 

[PROSPECTORMIKEL]

It seems that we continue to come back to the basics of the gold pan with each modification to improve the common sluce, which was not meant to finish the work without human interaction.

#/;0)--

 

[KevinInColorado]

"Black sand buildup is an age old problem with most sluices and losses are directly increased over the time of a run as we all know. My question to KevininCO is whether he experienced packing up to a point where his finger test did not easily penetrate the layer of black sand? If he experience a "cake" of black sand then the fluid dynamics of the sluice are changing over the run time and capture rates are changing with them directly."

No. In fact as the density of material in the sluice chamber increases I see an increase in the amount of black sand being ejected from the sluice. This is true for both the AMP and the Bazooka designs...and does not seem to result in an increase in gold losses. My comments are based on hundreds of hours of field use, not precise scientific testing.

 

[Timberdoodle]

"Black sand buildup is an age old problem with most sluices and losses are directly increased over the time of a run as we all know. My question to KevininCO is whether he experienced packing up to a point where his finger test did not easily penetrate the layer of black sand? If he experience a "cake" of black sand then the fluid dynamics of the sluice are changing over the run time and capture rates are changing with them directly."

No. In fact as the density of material in the sluice chamber increases I see an increase in the amount of black sand being ejected from the sluice. This is true for both the AMP and the Bazooka designs...and does not seem to result in an increase in gold losses. My comments are based on hundreds of hours of field use, not precise scientific testing.

Hi Kevin, I think you misunderstood my question/statement as it related to your own experience with the amp sluice and you mentioned a concern over the bed not being fluid in the same fashion a bazooka is fluid. I fully agree that a increase in material density increases in both sluices as material is exchanged and more black sand will have to exit the sluice as more enters over time. Just wanted to understand your comment over the lower part of the chamber not being fluid enough to provide exchange. I wasn't trying to address this as it relates to a bazooka, that's not an issue. Your thoughts?

 

[KevinInColorado]

Ah, right you are...sorry. The bazooka seems to maintain a relatively homogeneous fluid bed...meaning it is fluidized basically bottom to top. Whereas the AMP is not fluidized at all by some ways of looking at it. The upper half of the catch chamber empties out entirely if you give it a moment to clear. The lower half is active enough (via vibration we are told) to allow gold particles to enter and settle but it doesn't appear fluidized to the casual observer, it appears less active than the material behind a riffle in a drop riffle sluice.

 

[Timberdoodle]

Thanks Kevin. I certainly would have the same concerns based on your observations. If the vibration was truly effective enough to allow gold to easily penetrate then there should be no concern with a build-up of black sand to the level of the side inputs as I see it.

 

[Goodyguy]

I too have found that downward jets provide better fluidization of the trap than horizontal ones. I also like an additional row of jets pointing straight down from each tube.

The factor that must not be overlooked when designing the hole pattern, amount, and size of jets is to not loose the proper pressure of the flow coming from the jets.

If you overdo the quantity and size of jets then your pump may not be up to the task of supplying enough pressure.

The size of the trap as well as the quantity of tubes along with the size of the tubes as well as the spacing of the tubes both from each other and from the sides of the trap must also be taken into consideration.

GG~

 

[Goodyguy]

Here is a diagram of the hole pattern that I suggest. Same as yours except with a row of holes along the bottom of each tube.......
* notice all holes are staggered including the bottom ones.



(great minds)

 

[PROSPECTORMIKEL]

Has anyone here ever tried putting this on the other end of the sluice ?

I have seen it done on the GPAA gold fever show. They didn't show the results.

#/;0)

 

[johnedoe]

Has anyone here ever tried putting this on the other end of the sluice ?

I have seen it done on the GPAA gold fever show. They didn't show the results.

#/;0)

Uhhh ..... no pics!

 

[johnedoe]

Here is a diagram of the hole pattern that I suggest. Same as yours except with a row of holes along the bottom of each tube.......
* notice all holes are staggered including the bottom ones.

View attachment 1226090View attachment 1226099

(great minds)

Show off...........

 

[Au dave]

i found with my tubes that the centre row pointing straight down caused the trap to scour out when using a 1/4" grizz

 

[Jason in Enid]

i found with my tubes that the centre row pointing straight down caused the trap to scour out when using a 1/4" grizz

Then you need an inline valve to reduce the amount of pressure until your drop from "scour" to "fluidize". You should also be classifying far below 1/4 if you are trying to use it to trap fine gold. The water pressure that will kick out a 1/4 rock will blow out a flake in a heartbeat.

 

[Au dave]

i run mine on river power only and have changed to 1/2" griz

 

[goldog]

What ever happened to "think less...shovel more"?

 

[Jason in Enid]

What ever happened to "think less...shovel more"?

Isn't that the entire purpose the fluid bed? You keep running material over it, it just keeps collecting gold without ever packing up.

 

[PROSPECTORMIKEL]

Uhhh ..... no pics!

It was on TV and a few years ago.

However; if ( and only IF) I remember correctly, it was not powered from anything other than the water that flowed over the trap.

It was a small slit on the surface, with one edge beveled slightly, that created a low pressure area that pulled the small heavier material into a trap.

That is a lot for my decrepit old memory to get right, so DON'T QUOTE ME!
My memory can't be trusted.

If you still need pictures...

 

[PROSPECTORMIKEL]

Lost pics

Just one.

 

[Capt Nemo]

Here's my Model 4.1 6x14x2.5" fluid bed. The 6 tubes each have 11 3/32" jets on one side and only the last tube has 4 holes in the rear to break up the slightly more solid bench that forms at the tail of the box. The jets are angled downwards and all blow toward the head of the sluice. aproximatly 70 3/32" jets can be driven with a Tsunami 800 GPH bilge pump.

In operation, as you add more material the build up on the tail increases the depth of the bed, so you do have to watch how fast the material is added, or it will overflow. While overflow might be a problem solved by higher sides, the added depth may help keep any gold from being ejected. Inside the box everything is fluid except under the tubes. The jets effect seems to end at the next tube, so the back of each tube is a dead spot for gold to hide. The jets blowing transverse to the material flow gives highly fluid zones and drop out zones that the material must flow through. I have found that I can back off the valve a little and still run material just about as fast as I can dump it in. The black sand that is ejected is mainly by displacement. Fresh material will make the bed light colored, but the color will turn darker again with time. Cons are about 1/2 gal per cleanout. All in all, it seems to be working great on Lake Superior beach sand.

I am working on a grizzly so I can shovel directly in.