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Recovering flour gold from Concentrates........


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#1 rluckadoo

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Posted 28 September 2008 - 12:33 PM

Good Afternoon,

Just wasnted to give you all an update on the flour gold recovery that we discussed a month or so ago. I had asked for advice on the best way to recover some really fine gold from some dredge concentrates that I collected on a trip to CA. I considered Mercury, a shaker table, and a blue bowl. I decided not to go the Mercury rout, and a shaker table was a little too expensive for the small amount of concentrates that I had. Instead, on the recommendation of several of you, I purchased a "blue bowl" to try on the concentrates that I had collected. Well, I finally had an opportunity to get it up and running today and wantd to give a report on the results. I had just under 15 lbs of concentrates that were smaller than a window screen. It took me just under 4 hours to classify and run these concentrates through the bowl.

The blue bowl system was very easy to set up. I purchased the optional leg levelers which made adjusting the bowl a breeze. I classified the "smaller than a window screen" concentrates (I had already picked the pickers out of the larger material) into 30-, 50- and 100- and ran them separately through the bowl.

Here are my observations (and some tips) on the process and how the bowl worked on each classification:

Window screen- to 30 mesh Concentrates:

I ran this group first because I had a smaller amount of this size material, and figured it would be more forgiving if my water adjustments were not as precise as they should be. I found this material size to be a little too large for the blue bowl. The gold separated out very nicely, and ended up in a nice fan pattern around the center of the bowl, just like in the video; but, I ended up having to "snuff" up some of the black concentrates, as I could never get them to go through the center opening, even with the water turned up until it was running over the sides of the bowl. I think that for anything larger than 30 mesh, a desert fox or spiral wheel would be a better mode of separation. Luckily I only had about 2 cups of this size material.

30 to 50 mesh and 50-100 mesh Concentrates:

Both these classifications ran very well through the bowl. I would start the water off really slowly, and then gradually increase the flow and the concentrates began to separate themselves from the gold. In each of these runs, the gold finished off very clean and only a tiny amount of black sand remained. One thing I noticed is that once the concentrates started getting settled a bit in the gentle flow, I was able to take a rare earth magnet in a plastic bag and hold it at the water level to take out 50-60% of the black sands in there. The great thing about doing this in the bowl is that the gentle flow flushes any gold particles which are trying to stick to the black sand, back into solution and to the bottom. This method really worked well, as I panned the magnetite that I took out and no gold remained in it.

One other tip for you: As the flow started to pick up a bit and the fan pattern begins to develop with the concentrates in the bottom of the bowl, a rythmic tapping on the sides of the bowl (like the tapping in a gold pan to get the gold to move to the edge of the pan) really gets the gold to settle out of the black sands and stick to the bottom. Especially as the flow gets stronger and you can see some smaller particles of gold working up the center. Tapping on the edges of the bowl, settles the gold right back down into the bottom of the bowl and safely into the black sands.

Smaller than 100 Mesh:

This is some tiny stuff!!!! I really did not think there was any chance this bowl would recover this size gold. Honestly, you really have to look hard to distinguish individual grains. I had about 4 cups of this size material to run after the classifications. It is so fine, it feels like baby powder, or talc in your hands. Well, I turned the bowl off, loaded the first run of it around the edges of the bowl, and then very gently and very slowly started bringing the flow of the water up to speed. I started off with the water line about 1.5 inches from the top of the bowl (water just barely running into the center as a trickle). Gradually I increased the flow and tapped on the sides in a regular rythym. Soon, the fan pattern started to show and you could see a beautiful golden line start to develop around the outside edges of the pattern. I continued to increase the flow and the powder gold continued to be uncovered. Finally, with the water level around 1/2 inch from the top edge of the bowl, only a tiny band of black sand remained near the center of the bowl and a beautiful ring of powder gold about 1/4 of an inch wide was visible around the entire center of the bowl. I turned the flow off, snuffered up the gold and panned the tiny remaining amount of black sand out. I am proud to say that I ended up with a little over 1/10th of an ounce of the -100 mesh gold and a little less than 3/4 of an ounce of everything else smaller than a window screen.

I am VERY happy with those results. It was much, much easier that I thought it would be, and the recovery rate, especially for the really fine stuff, far exceeded my expectations. I would highly recommend this method to anyone looking to recover gold smaller than 30mesh. I still think my desert fox will work better for anything larger than 30 mesh. Overall, I am extremely pleased with the blue bowl. I hope these tips I learned today help you as well!!!

Thanks for reading,
Robert

#2 Micro Nugget

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Posted 28 September 2008 - 01:34 PM

Good job!! It is amazing how much gold is hidden in these fine concentrates. Sounds like you got the hang of utilizing tapping (gentle shock waves) to maximize recoveries.
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#3 El Dorado

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Posted 28 September 2008 - 03:21 PM

Glad you listened to good advice. It is an amazing unit for fine gold, maybe a bit slow but worth it. The 30 mesh plus is not that hard to pan with a small finish pan, the 30 mesh minus is where the bowl really shines! Were you running it off a garden hose or a bilge pump set-up? I have found the bilge pump seems to get a much smoother flow of water and no bubbles. Did you remember to use a bit of jet dry (to stop the floaters)? I have to get to Pioneer one of these days to get those levelers, gotta be the cats meow for getting the bowl set perfect.

Thanks for the feedback! Pictures would have been great!
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#4 rluckadoo

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Posted 28 September 2008 - 03:34 PM

QUOTE (El Dorado @ Sep 28 2008, 06:21 PM) <{POST_SNAPBACK}>
Glad you listened to good advice. It is an amazing unit for fine gold, maybe a bit slow but worth it. The 30 mesh plus is not that hard to pan with a small finish pan, the 30 mesh minus is where the bowl really shines! Were you running it off a garden hose or a bilge pump set-up? I have found the bilge pump seems to get a much smoother flow of water and no bubbles. Did you remember to use a bit of jet dry (to stop the floaters)? I have to get to Pioneer one of these days to get those levelers, gotta be the cats meow for getting the bowl set perfect.

Thanks for the feedback! Pictures would have been great!


Pictures WOULD have been great!!! and I can kick myself for not taking some during the process!!! Sorry!!!! I just didn't think about it.

I actually had already panned everything that was larger than a window screen. But, you are right!!! That thing is awesome on small gold!!! I did use a bilge pump and it was very smooth. (750gph) I didn't have jet dry, but used some diswashing detergent (a lot of bubbles in the bucket) but they never really got into the blue bowl. The water stayed very clear in there. I guess because the pump was below the bubbles in the tub.

The levelers were the ticket!!! When I started on the first run, the bowl was a bit off level and the concentrates began to bunch up a bit on the low side. I took a tape measure, turned the flow down pretty low, and leveled the bowl to within 1/16th inch all the way around. After that it ran great.

It was a little bit slow, but no slower than the desert fox, and certainly much faster and more effecient than panning. It took about 4 hours to set up, screen and run about 15lbs of concentrates (that had already been screened through a window screen). I could do it 1 hour faster next time, because set up will be easier the second time.

I can tell you, I am not one who is easily impressed. I am pretty impressed with the little blue bowl!

#5 jagdoctor1

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Posted 28 September 2008 - 07:39 PM

Great now rent out your services! I'll send you concentrates and you send me back the gold.... +10% for letting you see the gold....
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
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"So go forth, into the placer fields and hunt! Speak to bearded folk and dig a five gallon bucket of rusty crap. Listen to racket through headphones for days, maybe weeks. Bring sunscreen, snake chaps and bug repellent, water and a mild sedative. One day you will find one. It will be very cool." -Bedrock Bob (11/08)

#6 rluckadoo

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Posted 29 September 2008 - 07:41 AM

QUOTE (jagdoctor1 @ Sep 28 2008, 10:39 PM) <{POST_SNAPBACK}>
Great now rent out your services! I'll send you concentrates and you send me back the gold.... +10% for letting you see the gold....


I'd do it if they were already screened, and if everything was smaller than 30 mesh. Anything above 30 should be panned or, run through a desert fox (and I despise running that thing!) To me the screening was the most time consuming though.

I would consider it. How many pounds of concentrates do you have?...........................(I know you would have to be pretty "trusting" to ship your cons off to someone that you have never met..................although I consider myself a very trustworthy guy! Most of us would definitely have to ponder the thought a bit before sending them off........kind of like sending your kids off to college for the first time!)

#7 jagdoctor1

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Posted 29 September 2008 - 11:06 AM

I was kidding but honestly if I had alot I'd trust ya. I just don't have that much saved up ... Heck I still have alot of crushed rock I need to sluice to make concentrates hehe. I'm going to quartzite today to get some dirt to run so I'll be workin the sluice again soon.
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
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"So go forth, into the placer fields and hunt! Speak to bearded folk and dig a five gallon bucket of rusty crap. Listen to racket through headphones for days, maybe weeks. Bring sunscreen, snake chaps and bug repellent, water and a mild sedative. One day you will find one. It will be very cool." -Bedrock Bob (11/08)

#8 frank c

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Posted 29 October 2008 - 04:40 AM

Heres a tip for those who use the Blue Bowl and need levelers, take a piece of L shaped aluminun or whatever you can get your hands on thats L shaped, bolt 3 pieces to your 5 gal bucket in line with the 3 flip out U shaped supports that are on the Blue Bowl, Drill and attach 3 fine thread screws standing upright then add 3 large washers and 3 wing nuts.
The U shaped struts rest on the washers and the wing nuts below the washers are the perfect ticket for leveling, much less expensive and Much stronger and longer lasting than the Plastic components. Many of you may have these components laying around the garage or workshop already. I'll post a pick in the DIY section today.
Metal detecting ,Puffer Drywashers, Gold ,Meteorites, and Good Friends
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