QUESTION FOR ALL YOU FLUID BED HEADS!!!!

[QNCrazy]

I have been on this forum for some time and have done research on all the different sluices out there. Athough I haven't purchased a BGT, I have been sold on the idea of the fluid bed and am working on a project of my own.

I have seen several people modify their BGT grizzlies by placing smaller mesh screen over the existing ones. My question is if I was to leave the 1/2" does the fluidizing chamber lock up with the 1/2" material(rocks) or does it get blown out? Specific density/gravity is fueling my thought process here. It seems to me, it would depend on amount of water through the fluidizing chamber via the river current and the fluidizing tubes. If there was too much water flow, theoretically, everything could be blown out. Too little water flow, the chamber would load up and the gold would pass right through. If I had enough flow to move the 1/2" material out of the chamber, wouldn't I be blowing everything smaller out?

Help me out here. I look forward to your answers.

 

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[Rdg Sluicer]

I run mine without any screen over the Grizzlies and have no problem. I tried 1/4 inch screen for awhile but they seemed to get too clogged up with roots and such. I run mine in the fastest water I can find within reason of course.

 

[chlsbrns]

The documentation says that the trap remains full so there must be an exchange going on.

Documentation

It also says things about water flows and sizes of gold. My interpretation is that they lose gold.

We don't use sluices because of gold loss. We do use fluid beds!

What is it that you are making? A twist on the bazooka?

 

[arizau]

The densest material seeks the bottom of the trap and exchanges/displaces most of the less dense material upward to the point it is washed out. About the only way all the material could be blown out would be if the water injection was strong enough and was directed straight up as if it was a nozzle under a screen that fully covered the bottom. That could/would raise the fluid bed to the exit level and thus be washed out by the water that comes through the grizzly. The purpose of the tube injection is simply to keep the settling material loose (not allow an impenetrable bed to form) and facilitate the exchange of materials to take place with the rising current. The spacing of the holes in the tubes will only partially, if at all, scour the bottom but will mostly just stir it allowing further exchange to take place.
The larger rocks may take up a lot of space and the stronger up flow may hinder the settling of small gold especially the flour size but if they reach the bottom they will likely stay in the box.
Hope this helps you in your planning.

 

[chlsbrns]

If you want to make something new that will work take a look at http://www.banjopan.com/ Make a sluice similar to the banjo pan.

Wide at the inlet pinched or very narrow where the water enters at the edge of a bowl/pan. It will create a vortex that will hold the gold at the bottom of the bowl/pan while the other stuff exits.

It would be cheap and easy to make a pinched sluice that dumps into a plastic basin. Make a pinched sluice or even close the pinched end and drill a 3" hole in the bottom. Put a flange with a short pipe and a 45 or 90 degree fitting under the hole to direct the water/sands to a wash basin.

Pinched sluice: http://www.fastonline.org/CD3WD_40/CD3WD/APPRTECH/G10TOE/GIF/P339.GIF

It also would be real easy to add a hose/pump connection to the wide/water inlet side

 

[Goldwasher]

Large amounts of black sand and lots of flat rocks are the main reason to do clean outs with a Bazooka. Both can build up to the tubes and stop fluidization. if your paying attention to the trap you'll know. It only takes a second to run our finger side to side at the front feel the tubes feel loose cons go back to digging. If it feels locked up do a clean out. Seems like low flow make sure you don't have leaves or something blocking the tubes. Clean outs and resets are quick. Back before bazookas existed there were all the same discussions and possible complaints and critiques of stream sluices...and how often to clean out water flow build up etc...verbatum...Clean out an A51 five times a day every so many buckets YUCK!!!!!!

Loss due to size of gold is always related to its inability to settle in a trap vs. getting out of one!!!! Look at a miller table that stuff likes to hold tight even in the open. Give it a home and it will get real lazy. So since the trap may be 3.5 to 4 inches from deck to exit and you could kite out fine gold that hasn't settled....if it gets into that extremely deep trap in the specific gravity universe it will stay. As long as there is fluidization it will keep exchanging. So depending on source material, flow, and common size of gold you may have to run a little flatter and feed a little slower.

But, remember your not sitting at that stupid bucket classifier any more either. And you will move more material.

 

[QNCrazy]

Thank you for all your responses. This information helps. So basically, I need just enough water pressure to keep the bed fluid to allow the heavier material to exchange with the lighter material. I was considering installing a secondary classification plate to reduce to 1/4" but this information has changed the route I was headed as I am already classifing to 1/2". My project, which is based on ideas previously posted on this forum, is pretty much complete just have to do some field tests this Sunday. I will post video next week (success or fail) to get further input.

Thanks again.

 

[benny]

It's my belief that you'll need larger gravel in the trap to break up the upward flow of water from the tubes. This will cause more spots in the trap to become fluidized and so let the gold fall through. Some of the gravel will be caught by the flow over the trap, but most should stay in the trap. If I think that there's too much flow, I don't reduce the water, but flatten the angle BGT is set at to slow stuff down. Not enough glow, and I'll reverse that and put a steeper angle on the BGT.

 

[Rdg Sluicer]

The documentation says that the trap remains full so there must be an exchange going on.

Documentation

It also says things about water flows and sizes of gold. My interpretation is that they lose gold.

We don't use sluices because of gold loss. We do use fluid beds!

What is it that you are making? A twist on the bazooka?

So you read the directions and come to the conclusion they lose gold? I wonder what all that yellow stuff is in my box all the time?

 

[chlsbrns]

So you read the directions and come to the conclusion they lose gold? I wonder what all that yellow stuff is in my box all the time?

Yes. The documentation am pm's in my tnet inbox tells me that they lose gold. My experience with fluid beds also tells me that they lose gold.

The yellow stuff in your box is what it didn't lose.

Others have run what comes out of their trap thru the two bucket method and were shocked at the amount of gold that left their gold traps. Try it!

Maybe some of those who pm'd me will post and tell you what they got from running what passed thru their gold traps thru the two bucket method.

 

[Rdg Sluicer]

I look forward to it. Personally I pan my tailings a lot and very rarely see anything in them.

 

[Goldwasher]

If you want to make something new that will work take a look at BANJO PAN HOME - Banjo Pan Make a sluice similar to the banjo pan.

Wide at the inlet pinched or very narrow where the water enters at the edge of a bowl/pan. It will create a vortex that will hold the gold at the bottom of the bowl/pan while the other stuff exits.

It would be cheap and easy to make a pinched sluice that dumps into a plastic basin. Make a pinched sluice or even close the pinched end and drill a 3" hole in the bottom. Put a flange with a short pipe and a 45 or 90 degree fitting under the hole to direct the water/sands to a wash basin.

Pinched sluice: http://www.fastonline.org/CD3WD_40/CD3WD/APPRTECH/G10TOE/GIF/P339.GIF

It also would be real easy to add a hose/pump connection to the wide/water inlet side

You can't shovel into either of those things A pinch sluice is an old design used in mills the material run through them was very small. PRE_ CLASSIFIED see. feed size 1mm?? And considering when and where it was invented and the fact that it never became a widely used part of a recovery circuit speaks for itself. I don't think you under stand how much and what type material you can put through a bazooka. I'm pretty sure you have never actually used one....grasp why thousands of people who have used other boxes have switched and would recommend any prospector do the same. You might not realize that its ok to have different gear for different situations. Like I said before this is a subject of major discussion over the past century and Bazookas are what 5+ years old.It's one of many tools. All sluice boxes lose gold more or less in different situations. But, realistically when your familiar with your gear you end up running pretty dang near optimal. That's the key getting to know and understand what your doing. Sometimes its hard for people however. because they keep blaming the equipment no matter how well engineered...and not the operator.

 

[QNCrazy]

I feel this is the right time to post some results. Shortly after I posted earlier, I left work early and went to help my friend finish up his homemade highbanker w/gold hog mats. We decides to head out to one of our favorite dig locations near his house to test both of our projects. Sorry, didn't have a camera with me at the time and my phone memory is too low for video.
My project is a 55 gallon plastic barrel highbanker fluid bed. I got the idea from Astrobouncers bucket idea. Here are some build pics.





The last three pics I just took. So I ran it for less than two hours. I had it draining into my Jobe 45 just as a safety measure. When I shut down and cleaned the Jobe, not a speck of gold anywhere. However, in the barrel:

Success.

I have to make two more mods. First to add a fitting to attach a hose to help with cleanouts. Then I need to put in a drain plug of some sort. I was thinking of drilling a two inch hole in the bottom and seal it with a test plug.

So there it is, my project. I can run all day without cleaning it out. I can shut the water off and turn it back on any time without loss. Clean up was easy once I got the concentrates out of the barrel. I classified to 5/8. 1/8. Panned the +5/8 first then the +1/8. No gold in either of those. Then I panned the rest using a safety pan. Took all of 30 minutes. Look forward to you comments and questions.

 

[chlsbrns]

Nice I like it! No gold over 50 microns is getting out of there!

How many gallons per minute are you pumping into the bottom of the drum?

 

[chlsbrns]

You can't shovel into either of those things A pinch sluice is an old design used in mills the material run through them was very small. PRE_ CLASSIFIED see. feed size 1mm?? And considering when and where it was invented and the fact that it never became a widely used part of a recovery circuit speaks for itself. I don't think you under stand how much and what type material you can put through a bazooka. I'm pretty sure you have never actually used one....grasp why thousands of people who have used other boxes have switched and would recommend any prospector do the same. You might not realize that its ok to have different gear for different situations. Like I said before this is a subject of major discussion over the past century and Bazookas are what 5+ years old.It's one of many tools. All sluice boxes lose gold more or less in different situations. But, realistically when your familiar with your gear you end up running pretty dang near optimal. That's the key getting to know and understand what your doing. Sometimes its hard for people however. because they keep blaming the equipment no matter how well engineered...and not the operaclassifying. .

After a little thought and slight modification it would be easy to make it so that you can shovel like a madman without classifying.

Pinching is to speed up flow and settle the heavies to the bottom. The pinched end would be wide enough to have one or two 3 or 4 inch flanges attached to the bottom with grizzly bars or punch plate or whatever between the bottom and the flange. The grizzly spacing could be whatever size you prefer. The stuff larger than the grizzly spacing would fly off the end. The slight indentation at the flanges would probably trap nuggets.

Optionally a pump could be used at the wide end for places with little to no flow.

 

[Goldwasher]

how much material did you run?

 

[QNCrazy]

Nice I like it! No gold over 50 microns is getting out of there!

How many gallons per minute are you pumping into the bottom of the drum?

I am runing a two inch Harbor Freight pump. I think it is rated at +2500 gph at idle. As you can see in the photo, I split that and reduce to one inch pipe and control the flow to the highbanker spraybars and the fluid bed spraybars with the ball valve. At Idle speed with both valves full open, I have the perfect flow conditions. However, when I want to take a break, I turn the fluid bed to 3/4 open before closing the highbanker valve. I can either leave it like that and it will continue to fluidize or I can shut it down completely. To answer your question, i don't know exactly. That would require a mathmatician to figure that out. There are some charts that provided information on flow volume for pvc pipe. My pump is rated up to 58 psi but at idle speed i'm no where near that.

 

[QNCrazy]

how much material did you run?

Maybe four buckets. I spent a lot of time breaking up the ground and moving a large boulder. The fluidbed spraybars were not adjusted correctly initially but once I adjusted them a little higher on the drain hole end, it was working perfectly. I am going to have to make some spacers/legs to ensure proper adjustment each time.

 

[chlsbrns]

Cool! As long as everything stays fluid it's going to work and retain the gold.

Good job!

 

[QNCrazy]

I'm a couple of days late but here is a short video of my run on Sunday. I'm going to start another thread on this in the highbanking section.