Fluid bed tech info?

[Hephaestus]

Hi everyone,

Working on a fluidized bed highbanker design. I've spent inordinate amounts of time reading just about every thread here...

Wondering if you guys have run across research on extraction using fluidized beds?

Curious if there's data on feed rates / volumes of water, better fluid distribution models than the ones we typically see DIY'd. Pan shape etc.

I started this simple, and after realizing the cost to 3d print at the library is cheaper than the galvanized tin & plumbing bits I intended to use - I'm having new thoughts about the fluid bed. Incorporating the pipes into the design, drawing the nozzles in at specific angles instead of halfhazardly hand drilled...

But I figure there must be research my Google-fu just isn't finding on the topic. I figured I'd ask here since I know some of you probably have some long saved links on the topic that I'm clearly not using the right terms to find...

Thanks in advance!

 

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[Hephaestus]

Maybe this will make it clearer what I'm looking at doing... And wondering if there's details on how best to make it work.

Tons of tech articles on riffles etc, but little to tell me efficient ways of doing this and what I can run for a feed rate through on a fluid bed. I'm assuming square box with water shooting around randomlu isn't the best method - but it works.... And if I do go to a printed box - forming the box around the pipes or incorporating the pipes into the print as structure + directed flow + task oriented fluidization becomes easier.
Do I make more sense now?

 

[mytimetoshine]

My understanding is you can make a fluid bed hibanker work but it just isnt worth the extra hassel. You need a large pump or 2. there are better options out there

 

[Hephaestus]

And yet there are many 55g drum fluid bed highbanker builds... And bazookas are still some of the more popular styles of sluice. Look at the outlet box concentrator - how many thousands have been built?

Could it be that maybe the pressure/flow needs is due to poor design? Resolve the issue of poor design and water distribution by increasing flow until it works?

Guessing the tech data isn't out there... Anyone have some solid understanding of fluid dynamics or a practiced eye at understanding where gold will settle?

 

[N-Lionberger]

I really doubt there are thousands of outlet box concentrators LOL

 

[winners58]

might check out some member pages to get some ideas.
from QNCrazy http://www.treasurenet.com/forums/dredging-hi-banking/452244-55-gallon-fluid-bed-highbanker.html
and maybe page 2 fluid bed sluice or page 3 for the "add a trap" of GoodGuys build's
http://www.treasurenet.com/forums/goodyguy/135031-gold-prospecting-equipment-2.html#post3831903

 

[Goldwasher]

The water in a Bazooka is not "spraying" and its holes are not drilled haphasardly.

Running one with a pump is problematic. It needs twice the water of a comparable powersluice and it is not a better producer for its size.

I do believe a purpose built fluid bed powersluice is doable that doesnt us as much water. However I would still want some normal riffles or other non fluidized recovery in the system.

The thing is when dirt, gold and water get together gold drops out. It really doesn't matter how teriibly built a widget is it will still catch gold.

Sometimes trying to change the widget makes it work worse than it originally did.

Like trying to make a Bazooka a hibanker.

There is a reason there isn't much technical info out there . Not many people are doing it.

There are Three people in the U.S. that built Bazookas from start to finish. I am one of them.

The Croc Gold trap is being made in Australia now . It is an exact copy but made better.
The Grizzly Gold trap is another version of a fluid bed gold trap it is an improvement on the design.

The biggest thing is exchange you want the trap to be pretty fluidized. Especially in a powered unit as you will have/want a higher feed rate.

The stream sluice is more forgiving. It can run at really low flow and still catch gold.

But guess what... The fluidization isnt really whats catching the gold. Its caught cause it falls into a hole. It's pretty simple really.

Fluidization allows for exchange of the gangue material. Low flow affects the exchange and the ability of the water coming out of the tubes to recover.

With any model at low flow the fluid bed is locking up at every introduction of material if it isn't regulated properly. If the top layer that was just added isn't given a chance to exchange an have any gold settle into the fluidized layer. The next addition of material may not fluidize at all and just compounds the problem.

If I'm in a situation that I have to babysit a fluid bed that much I'm gonna go for a drop riffle.

Same reason I will never use an Amp too much babysitting with lack of increased production.

The best fluid bed traps are 36" sniper size and bigger. Running in fast water with as shallow a grade as you can get.

The Mini and super mini sized models. Have poor recovery rates as the traps are too small and load up very quickly.

Even when the company was in business I thought we should drop them from production..

The only reason they were available is that people wanted a cheap entry level way to buy into the trend.

For production size matters.

Same thing will apply to a powered fluid bed "hi-banker" If your gonna design one make it so it can handle good feed rates and the trap stays active. Don't make it too short or its just a glorified drop riffle.

Make the trap too long and it will hold more cons than you want. But, will still have good recovery.

 

[Hephaestus]

Winners58, those are some of the threads that made me ask here to begin with.

Goldwasher: thanks for an eloquent reply. I agree with a lot of what you have said. Maybe random flow wasn't the best choice of words - but a lot of the current fluid bed systems seem more to be drill holes around this axis and that should do it.

I'm no gold expert, I know that. I've only owned a pan for a little over a year. I'm working typical Alberta flake - really fine, no hope of finding pickers or nuggets. I've been concentrating with a pan, packing out, then finish at home with a Craigslist special 36" sluice with riffles and mat that I feed into a rubbermaid origin diy fluidized bed concentrator (copied the RMC design) I know the fluid bed recovers most of my gold, then that to a wheel.

The fluid bed catches 98% of what I get. I keep saying I'm just going to sell the sluice.

This is why I think fluidized is best in my case. It seems to work well on the flour we have around here.

My thoughts were to use a clamshell style gate to regulate flow of paydirt, (also gives me a chance to stretch/ smoke without worrying about feed rate). I think like you at first I probably would run another set of riffles after the fluid bed to verify its catching most(?) Of what I want.

I admit I do struggle with KISS vs Arduino / automate that stuff. My brain is always thinking there's got to be a better way. But I have a strong hunch the current fluid beds square box construction isn't improving the feed rate issue, the pump / pressure / flow needs, nor the recovery rates. Maybe I'm wrong. But I have a strong suspicion that I'm not too far off - but my knowledge of fluid dynamics in a slurry is definitely lacking.

 

[Timberdoodle]

There's not much technical information out there on "fluid beds" for gold recovery, but there is good information on elutriation for gold recovery. Search the web for the following
MIRL REPORT NO. 91 ELUTRIATOR DESIGN MANUAL FOR COARSE HEAVY MINERAL RECOVERY FROM SLUICE BOX CONCENTRATE
The limitations of gold recovery and operation in a elutriator are very similar when you eliminate the difference in feeder design. The smaller the gold the less settling velocity is has and maintaining high recovery rates requires screening to a size fraction.

From my own experience:
It's very important to aim any jets downward. Any direct jet flow that can send material upward will help keep gold in suspension and cause loss of fine and flaky gold. The jets are faced downward and the up-welling of flow is adjusted to maintain fluidization. Its also beneficial to offset the jets to create a small swirling eddy near the bottom level. It is good to have an input end and an outlet end with a few degrees of downtilt, this allows material to migrate down the length of the bed. (you do not want to add material to the outflow like the RCM)

I have built and tested lots of fluid bed designs in the past 2 years. When material is screened and fluidization adjusted to match they are very quick and have great recovery. That being said what separates a fluid bed operation from a sluice? Classification still rules! A sluice can be made to include riffle functions to work a multiple of size fractions. A fluid bed design for a highbanker should require at least 2 levels of screening 3/8 and 1/8 and probably 3 (20 mesh)if you are chasing flour gold. A hybrid system is now my new goal.

Good luck with your fluid bed project. I hope I was helpful. Having a 3d printer for the past 6 months has made r&d so much easier for me.

 

[Hephaestus]

Funny, how everything has been done before, that's what was driving me nuts, I knew the water column method had been done - but couldn't google the correct name.

Wonder at how effective the pulsing is at helping settle the gold out.

I'm negotiating on a used creality cr10, I have a feeling I'm going to want to use it more... A lot of this stuff seems a lot simpler if it can be printed vs run on a lathe...

 

[Timberdoodle]

I have a creality cr10. It's done everything I need it to do so far without any issues. Even small riffle decks take 10-12hrs to run and I have made entire fluid bed designs which can take 40hrs to build so having one at home is beneficial.


There are several commercial pulsing elutriators out there. They do seem to work well but get complicated.

 

[Hephaestus]

Yeah, our library has a MakerBot costs about nothing but often wait days for a chance to run what's next.

CR10 could do wonders for prototypes, just testing Riffle designs against matting it could pay for itself.

 

[QNCrazy]

I still stand by my 55 gallon design. I haven't used it in a while due to overregulation and don't want to take a chance. If I had to do it again, I would lower the spray bars in the fluid bed to no more than 1' from the bottom for better control of the fluidizing action. I use a 2" HF pump. With the current set up, 2-3 inches off the bottom, the valve controlling the fluid bed is at about 2/3 open when running which causes a flow fluctuation when I shut off the top spray bars. The flow to the fluid bed needs to be constant. I know how to adjust my sytem for best results. Basically, i don't shut down the spray bars. The other option is to have a separate pump running the fluid bed.

Mike