Bazooka sluice with ocean beach sands

[arizau]

Has anyone tried using their bazooka or a home made fluid bed sluice on ocean beach creeks using only the fine beach sand as feed material? The vast majority of these sands are minus 100 mesh and the gold is mostly much smaller. I know of all the other recovery options and I am just wondering about bazooka or fluid bed results.

 

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[Aufisher]

Sounds like most use the gold cube. The Zook will catch pretty darn small gold though...

 

[KevinInColorado]

If you run just heavy beach sand, the Bazooka catches the +100 gold very, very well. However it spits out a fair amount of the -100 gold. To fix this, you have to preload the fluid bed with more normal gravel. That's based on some testing I've done, your results may vary.

 

[arizau]

KevinInColorado - I saw your post about the beach sand test and had previously wondered about what influence larger material has in fine gold capture. I had surmised that the larger cobbles might work similarly to that of ragging in a gold jig* and your test may have proved that. What size material did you pre-load with and was much of it ejected?
*Mineral Processing Design - Google Books

 

[KevinInColorado]

KevinInColorado - I saw your post about the beach sand test and had previously wondered about what influence larger material has in fine gold capture. I had surmised that the larger cobbles might work similarly to that of ragging in a gold jig* and your test may have proved that. What size material did you pre-load with and was much of it ejected? *Mineral Processing Design - Google Books

Good questions! I preloaded with quartz/granite type gravel that was just under 1/4". I agree that those gravel pieces act a lot like ragging in a jig. There was some ejected as the heavy beach sand replaced it in the trap. Less than 1/2 cup ejected I would say but of course I only ran about a gallon of beach sand.

I too feel large cobbles act like riffles in the creek. In my favorite creek, the spots with big cobbles are exactly where the gold accumulates! Part of it of course is the simple fact that larger cobbles and gold are both dropped by big storms (the creek rises 8 feet in a really big storm!) in the same spots but my theory is that smaller storms which move flood gold will drop it due to the turbulence from those large cobbles.

 

[arizau]

Good questions! I preloaded with quartz/granite type gravel that was just under 1/4". I agree that those gravel pieces act a lot like ragging in a jig. There was some ejected as the heavy beach sand replaced it in the trap. Less than 1/2 cup ejected I would say but of course I only ran about a gallon of beach sand.

I too feel large cobbles act like riffles in the creek. In my favorite creek, the spots with big cobbles are exactly where the gold accumulates! Part of it of course is the simple fact that larger cobbles and gold are both dropped by big storms (the creek rises 8 feet in a really big storm!) in the same spots but my theory is that smaller storms which move flood gold will drop it due to the turbulence from those large cobbles.

It seems to me that one could load large enough stones to create a false cobbled bottom/ragging that rests above the bed of the box on and between the tubes. This may serve the same purpose as smaller stones and they would be less likely to be ejected while the smaller material, sand in my case, still could be. In any case, loading of the box with heavy black sands may be problematic and thus effect capture efficiency.

 

[KevinInColorado]

It seems to me that one could load large enough stones to create a false cobbled bottom/ragging that rests above the bed of the box on and between the tubes. This may serve the same purpose as smaller stones and they would be less likely to be ejected while the smaller material, sand in my case, still could be.

give it a try! My test did still lose a small amount of -200 gold so there is still room for improvement if you face really fine gold!

 

[arizau]

If you run just heavy beach sand, the Bazooka catches the +100 gold very, very well. However it spits out a fair amount of the -100 gold. To fix this, you have to preload the fluid bed with more normal gravel. That's based on some testing I've done, your results may vary.

Hey Kevin,
I have been thinking about the addition of pebbles in the box and whether it then actually captured more gold or if maybe it just helped to create a super concentrate that, when panned, would have more gold per tablespoon (I am assuming that you panned in small quantities to see gold capture) than what you were finding in the other test run without the pebbles. When I think about, it is obvious that pebble addition substantially decreases the volume that is available for black sand/gold capture which then could lead to super concentration. This then could lead to a further dilution of gold per tablespoon in the tails with the addition of more black sands. Whether it captures
more gold or super concentrates the thought of less panning for recovery is a plus. Any thoughts?
arizau

 

[KiddoTheMiner]

Are you saying you found gold in sand?

 

[Prospector70]

Are you saying you found gold in sand?

Of course! Gold is everywhere if you look small enough. Heck, you can even find it in the right bag of playground sand from home depot.

 

[KevinInColorado]

Hey Kevin, I have been thinking about the addition of pebbles in the box and whether it then actually captured more gold or if maybe it just helped to create a super concentrate that, when panned, would have more gold per tablespoon (I am assuming that you panned in small quantities to see gold capture) than what you were finding in the other test run without the pebbles. When I think about, it is obvious that pebble addition substantially decreases the volume that is available for black sand/gold capture which then could lead to super concentration. This then could lead to a further dilution of gold per tablespoon in the tails with the addition of more black sands. Whether it captures more gold or super concentrates the thought of less panning for recovery is a plus. Any thoughts? arizau

It did actually retain more gold. I was capturing the tailings each way and comparing the two runs of the same material. For further progress in retaining super fines I think you'd have to reduce the pressure in the fluidization tubes.

 

[arizau]

It did actually retain more gold. I was capturing the tailings each way and comparing the two runs of the same material. For further progress in retaining super fines I think you'd have to reduce the pressure in the fluidization tubes.

Thanks. Now back to the drawing board errr I mean rock sorting.

 

[goldhog]

Thanks. Now back to the drawing board errr I mean rock sorting.

I'm just dumping some thoughts in here from our fluid bed testing last year.
I'm tired........ so excuse me if it doesn't make total sense.
......................................................................
I think the first step is to understand the CAUSES... then come up with your cure.
A big part of the issue with black beach sands is "hydraulic equivalence".
Understand THAT... and you'll better understand your causes.
In a nutshell............
Fine black sands and the gold are similar in size.
However, much of the black sands are spheres and much of the gold is flat.
(I'll try and find some pics from under the microscope.)
So, even though the gold has a higher specific density, they are still "hydraulically equivalent".
This often causes both losses and impaction on any type of water based separation method.
Adding the pebbles in the right size based on the pressure of the bed can help.
The volume they take up often helps keep the bed fluidized somewhat and keeps it moving.
Still... losses are always higher when running this type of material.
You can also email Mike at the gold cube.
His black sands testing on the cube and other devices was very good.
20 - 30 % losses are not unusual when doing very controlled and measured testings.
Doc

 

[arizau]

I'm just dumping some thoughts in here from our fluid bed testing last year.
I'm tired........ so excuse me if it doesn't make total sense.
......................................................................
I think the first step is to understand the CAUSES... then come up with your cure.
A big part of the issue with black beach sands is "hydraulic equivalence".
Understand THAT... and you'll better understand your causes.
In a nutshell............
Fine black sands and the gold are similar in size.
However, much of the black sands are spheres and much of the gold is flat.
(I'll try and find some pics from under the microscope.)
So, even though the gold has a higher specific density, they are still "hydraulically equivalent".
This often causes both losses and impaction on any type of water based separation method.
Adding the pebbles in the right size based on the pressure of the bed can help.
The volume they take up often helps keep the bed fluidized somewhat and keeps it moving.
Still... losses are always higher when running this type of material.
You can also email Mike at the gold cube.
His black sands testing on the cube and other devices was very good.
20 - 30 % losses are not unusual when doing very controlled and measured testings.
Doc

Doc,
Thanks for your input and the email tip. I've watched your video/explanations on hyd. equiv. and from them know that is the probable cause of losses of fine gold particles in any capture device. I highly recommend to all that they watch your videos particularly the instructive ones such as the one above, explanations about surface tension and your ones on panning techniques. One of them about your Gold Cyclone also addresses the fine gold/black sand hyd. equiv. issue mentioned above if I recall correctly.

 

[goldhog]

Glad they helped.
I think understanding H.E. is one of the most important things a prospector / miner can do.
Not only in recovery, but also locating gold.
Cheers up.
Time to rest up.

 

[gold hound]

Nice!!! Wouldn't have thought of doing that! Just bought a bazooka! That info may become very useful

 

[Kamorle]

I bought the s1 finishing/concentrating sluice with the vibrating hopper for the black beach sand where I live. It works quite well and no loss. Now if the gold was only a bit more chunky it might pay for itself;-)