Inside of a fluid bed sluice underwater

[Bbarton]

For those interested in what the inside of a fluid bed sluice looks like while running, here is a few GoPro videos I took while sampling a spot, and testing the sluice again today. You can see the large amount of flat rocks in my area that like to make their way into the trap. Had one get in that was nearly 4" long as well. Trap was working well otherwise and my sampling produced a large amount of flour gold as well as some nice flake and a few small crystalline pieces. Had one small piece of quartz with a bit of gold on it too. The trap seems to be working quite well. Two of the videos show the trap without any material introduction and one video shows it being fed. The video of it being fed ended up having the camera focus on the silicone where I sealed a part unfortunately, but what's happening can still be seen.

https://youtu.be/dY5n2wouVYg
https://youtu.be/wZq2KDHQLCI
https://youtu.be/sT2uc3kQB68


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[crumbaker]

After seeing various videos like this and my own experience with my own bazooka, I don't think the holes in the tubes that are located in the fluid bed part are doing anything. I think it would work just as good without them. The flow just isn't strong enough to move the rocks around, what's doing it is the water flow going down into the trap(main entrance) along with additional material. That seems to be what's keeping it fluid and circulating the material. The tubes themselves might help though as a barrier to too much material leaving, I'm not sure about that though.

 

[Bbarton]

After seeing various videos like this and my own experience with my own bazooka, I don't think the holes in the tubes that are located in the fluid bed part are doing anything. I think it would work just as good without them. The flow just isn't strong enough to move the rocks around, what's doing it is the water flow going down into the trap(main entrance) along with additional material. That seems to be what's keeping it fluid and circulating the material. The tubes themselves might help though as a barrier to too much material leaving, I'm not sure about that though.

The tubes keep the trap fluidized so the material of higher specific gravity can displace material with lesser specific gravity and push the lights out while filling the trap with heavies. The tubes aren't meant to throw out the big rocks, they just make it so the heavies can sink and the laminar flow can take care of the rest which is why it works. The laminar flow by itself could not penetrate the drop and could not scour material unless there was a large diverter in there. As I picked up the box to cleanout today, I let all the water flow out until the trap "locked" and I then held it in the flow of the creek with only the tubes getting water to watch how it would react. As they started to get water and fluidize I actually saw the trap "lift" as the water "unlocked" the trap and it went back to a fluid state. It was pretty neat.


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[Hunt4gold]

The tubes keep the trap fluidized so the material of higher specific gravity can displace material with lesser specific gravity and push the lights out while filling the trap with heavies. The tubes aren't meant to throw out the big rocks, they just make it so the heavies can sink and the laminar flow can take care of the rest which is why it works. The laminar flow by itself could not penetrate the drop and could not scour material unless there was a large diverter in there. As I picked up the box to cleanout today, I let all the water flow out until the trap "locked" and I then held it in the flow of the creek with only the tubes getting water to watch how it would react. As they started to get water and fluidize I actually saw the trap "lift" as the water "unlocked" the trap and it went back to a fluid state. It was pretty neat.


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Barton is correct - nice videos by the way... The water coming out of the tubes keeps the material within it in a slight state of suspension, which in turn promotes stratification of the material within it according to its specific density. Have been running tests on fluidization - flow velocity through tubes vs hole sizes and layout, chamber size, etc. It is an effective method of trapping gold.

 

[Goodyguy]

Have been running tests on fluidization - flow velocity through tubes vs hole sizes and layout, chamber size, etc.

A few years ago when I built my first fluidbed I experimented with larger and smaller holes in the same tubes thinking that I could even the flow out of the jets from one end of the tube to the other.

What I discovered was that water followed the path of least resistance and my theory of sending more flow past the larger holes to the smaller holes was flawed.
I also tried it the other way around with the same results of having uneven flow through the jets.

Just wondered what your thoughts or results have been or if you have tried that experiment? Recently It was posted that the factory bazooka was using that theory. And bazooka owners seem to be happy with their sluices performance.

I did find however that I could even the pressure in all three tubes from one end to the other by connecting them together at the far ends and leaving all the holes in the tubes the same size.

Your thoughts?
GG~

 

[Capt Nemo]

Water hammer in the tubes always favors the far end of the tubes (especially long ones).

One way to think about equalizing pressure is the summing junction in electronics. As long as all the impedances are equal, the voltage will add or divide evenly. It's why I folded the manifold on my model 4 fluid bed. I fed the manifold at 3/4" to 1/2" pipes. The 90 degree elbows would look like identical impedances and should divide with similar pressures. They did for the most part with slightly higher pressure at the far end of the manifold than the near, again due to water hammer. The pressure difference is really noticeable when first loading the bed, but once full, everything is even again.

 

[Goodyguy]

Water hammer in the tubes always favors the far end of the tubes (especially long ones).

One way to think about equalizing pressure is the summing junction in electronics. As long as all the impedances are equal, the voltage will add or divide evenly. It's why I folded the manifold on my model 4 fluid bed. I fed the manifold at 3/4" to 1/2" pipes. The 90 degree elbows would look like identical impedances and should divide with similar pressures. They did for the most part with slightly higher pressure at the far end of the manifold than the near, again due to water hammer. The pressure difference is really noticeable when first loading the bed, but once full, everything is even again.

If I understand you correctly you are saying that once the tubes are submerged the pressure through the holes evens out even if they are all the same size ?

 

[crumbaker]

maybe the sniper model has holes that are too small, but when I submerged just the bottom half of my bazooka in a somewhat strong water flow hardly any water was coming out of those tube holes. I don't see how it could keep even light sand fluid. Try it yourself if you have that model. Especially in comparison to what a water flow would do coming down from the main trap. I might build one both ways and do some tests with lead. I'm still fairly certain at least on the sniper model that the tubes aren't doing anything real to retain gold. I think it's all about that trap.

 

[goldog]

Give it a try. You may be on to something.

 

[crabtree]

maybe the sniper model has holes that are too small, but when I submerged just the bottom half of my bazooka in a somewhat strong water flow hardly any water was coming out of those tube holes. I don't see how it could keep even light sand fluid. Try it yourself if you have that model. Especially in comparison to what a water flow would do coming down from the main trap. I might build one both ways and do some tests with lead. I'm still fairly certain at least on the sniper model that the tubes aren't doing anything real to retain gold. I think it's all about that trap.

You could easily test your theory by plugging your tubes with small corks.

 

[jcazgoldchaser]

For those interested in what the inside of a fluid bed sluice looks like while running,

Dude, that's so cool.

Next time you're out and before you leave, reload the trap then take your degolded cons and slowly run them through. Would be interesting to see heavies as they enter the trap and how soon they sink and what not.

And, you know, just to be safe, put a catch pan at the other end.

 

[russau]

Ive found that when running any pipe of the same size at length ,the longer you make them them the LESS pressure youll have at the ends and LESS flow. In running pipe (to maintain pressure at the ends) you need to size down the pipe and the holes need tobe of smaller size at the start and bigger on the end . this will help equalize a constant pressure / flow to all ports. OTHERWISE if you have the same size pipe and holes (ports) youll have a lot of pressure and flow at the beginning of the pipe and less to the ends............BUT running short lengths of pipe , it wont matter much!