# Back to Black sands



## warlead (Sep 18, 2008)

So its coming up on the end of dredge season and I have concentrates sitting around in 5 gallon buckets. I usually run this through a clean up sluice and thats about it. I know there is more gold that I am just throwing away. 
I was wondering if I could take say a gallon of concentrates at a time and dump a couple gallon of AR into it, let it sit for a while (days?/week?) and then drop it out. Or is there a better easier way?

I have read the other black sands posts and I am not looking for something to recover the gold fast. I have a pole barn and just figure if I can fill buckets with AR and let sit outside to work their magic and go back in a week or so to drop and then heat in a cupple I would be good.

What do you guys think?

Hey LaserSteve you ever process that black sand I sent you?


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## Shecker (Sep 18, 2008)

One of the problems with using AR on black sands is that the black sands contain a lot of iron which causes co-precipitation of the values. So the first approach would be to remove as much as possible all of the magnetic iron.
But also keep in mind that you can have non-magnetic iron that can do the same thing (loss of values to insitu reaction). I would begin with thorough drying followed by magnetic separation. This will break any ionic charges that the magnetite may have. Once separated take a small amount of the magnetic material and digested it in hot HCl. If there are encapsulated precious metals in the magnetite a brown to black residue will remain. If there is none the magnetic fraction can be discarded. 

Then take a small amount of the non-magnetic fraction and dissolve it in hot HCl. This should remove any base metals present. It won't remove materials like titanium and rare earth minerals but neither will AR.
Therefore the small sample you are testing can now be treated with a hot AR solution. You can chose the option of cold AR to recover gold, followed by hot AR for platinum group metals. Silver present will report as silver chloride.

I hope you find this helpful.

Randy in Gunnison


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## warlead (Sep 18, 2008)

Thanks shecker. I normally would dry and then separate the magnetic material even before running it through the clean up sluice. Though usually I just pitch it  Its a great idea to check it first though.

So the process so far is:
1. Dry
2. separate magnetic material
3. digest magnetic material in hot HCL
4. digest non-magnetic in hot HCL
5. cold AR to recover gold
6. then hot AR to recover PGMs (of which there probably are since platinum nuggets have been found in the area I work.)

Am I missing anything?


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## Shecker (Sep 18, 2008)

Or if you don't mind having the gold and any pgm mixed in the same solution use hot AR. An alternative would be HCl-Cl. But remember this -- the more systematically you approach the problem the easier the answer becomes.

Randy in Gunnison


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## Smitty (Sep 18, 2008)

Warlead, I had some time messing with black sand and my experience took weeks to dissolve the blacks. Although I have not messed with prospecting much lately I had the idea of crushing the blacks with a mortar and pestle first before I try and dissolve the black sand, hope that was spelled correctly. Make the black sand as fine as possible before dissolving. I tried cracking it with heat and cold water, but it was already so small it did not do anything. It was non magnetic black sand I was experimenting on.


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## Shecker (Sep 18, 2008)

I have also spent a great deal of time messing with black sands. I use to have an incredibly rich black sands just outside my front door and lots of time on my hands. About a year ago an associate of mine gave me some
black sand to test and told me that it was extremely difficult to work. I had the answer in half an hour and clean separated metals in an hour. It can be done.

Randy in Gunnison


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## OMG (Sep 18, 2008)

I have also been messing with black sands (for about a year), trying all sorts of things. I have come to the conclusion that it is way to expensive and time consuming to use acid to dissolve the base metals.
Although, if you have nothing but time, you could set up some electrolysis rig to leach the base metals, plate/deposit them out in a separate area (and filter them), and it would regenerate the acid so no more acid is required for the cell.
The most efficient thing I've found to dissolve base metals including pyrites is caro's acid. I have used this, then used homemade AR and actually recovered some gold from the blacks sands. Even after caro's acid, repeated HCl washes, the AR still took out ALOT of base metals. And I'm sure there are still base metals in there.
Although in hind site I should have crushed the material to a powder first.


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## Anonymous (Sep 18, 2008)

I have had 1/2 cup of black sand soaking in hcl for over a year, changed the acid 4 times even though it was not used up. I do occasionally check with a magnifier and can see the tinest pieces of gold in there. But based on counting the number per sq inch and estimating that to cubic inch. The amount of gold exposed is smaller than the period at the end of this sentence. And is not even close to the value of even the first acid soak.

Jim


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## warlead (Sep 18, 2008)

so it seems AR, HCl, etc are not cost effective, based upon peoples posts? maybe just the old fashioned cooking of the cons with iron to create lithage (sp?) would be the most effective. I guess I should start building that furnace


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## Shecker (Sep 18, 2008)

Why not try something remarkably simply. Iron, as the iron in magnetite, is a cementation agent for displacing other metals from solution. So if you have clean magnetite that is load with intergrown precious metals, why not use the reducing capability of the iron to replace it something more conductive to precious metal recovery. To keep it simple, make a concentrated solution of copper sulfate (cu(II) Sulfate) and sulfuric acid.
Add the copper sulfate acid mixture to the magnetite and stir occasionally. A little heat will help. If a reaction transpires then the iron will be replaced with copper and you now have a copper/pm material that after washing and drying will be a whole lot easier to smelt or chemically treat. v How long this will take is the subject of experimentation.

Randy in Gunnison


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## lazersteve (Sep 18, 2008)

Randy,

In the effort to keep the experiment really simply, why not just test a small sample of fine mesh material with dilute sulfuric acid (33%)?

This will dissolve the iron oxides and likely leave behind a much smaller residue of any precious metals present along with other insolubles. This way your results are not contaminated with the precipitated copper sludge from the added copper sulfate as you suggested. There is no real need to introduce the copper sulfate simply to precipitate the copper it contains. 

In my experiment you can get an idea of what is actually in the iron oxide, in yours you are assuming the added copper sludge contains values without really knowing by visual inspection, plus you will still have to remove all that copper to find out for sure.

Steve


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## Shecker (Sep 18, 2008)

Steve

I am sure you understand that one of the great beauties of chemistry is that there many ways of doing the same thing. And you are right it can be as easy as H2SO4 unless there are things in the sands that can form odd complexes as sulfates. And the only way to tell that is by experimentation.
I would not, as an example advocate CuSO4/H2SO4 or HCl on black sands that contain rare earths. Some of them can form volatile compounds. It always helps to know the source of the black sands. If it is a rare earth bearing placer than the approach would be different (and if I said I know much about rare earths other than things like Monzanite and a few other simply things you could shot me in the morning).

Randy in Gunnison


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## OMG (Sep 19, 2008)

Unless you are just experimenting for fun, I seriously think that dissolving black sands to get at the gold is a waste of money (unless you are somehow regenerating the acid). I wasted my money on doing just that in many different ways.
Like I said in my previous post, I used caro's acid (which is a very powerful acid - it even dissolves carbon), then let the sands soak in HCl a few times, then when I used AR on the sands, there was still lots of base metals that got pulled out.
If you do the math on how much acid it would take to dissolve all the base metals in a 5gal pail of black sands (so you could be sure that you are not throwing away any gold) it would cost a fortune.

Shecker, you say copper sulfate will dissolve iron oxide (Fe2O3/Fe3O4). Do you know the chemical reaction for that? Does the copper then precipitate as a copper oxide/hydroxide?


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## blueduck (Oct 1, 2008)

In working with various blacks and brown sands, I wonder if the Chinese still did not hae the right idea, heat first, which burns off any sulfides, and then use acids to pull the gold.

And then too, what about using a ball mill to pulverize to 200 mesh or finer and then use a cyanide leach similar to the action mining units for pulling platinum in their spendy units? On a small scale it should still be profitable to work with it, the only problem is the stigma attached by the public to cyanide use due to the problems from back in the 1930's and earlier..... 

And if a person did use a ball mill, then used a non-concentric vibrator to settle the heavier gold toward the bottom, skim off the top layers and then use acid on the leftover would that not lessen the amount of acid needed, and yes while more work looking at it from the outside to a degree, your fines if all the same size should displace rather easily as the specific gravity of those fines determine if they float or sink..... and of course there is always the use of a small shaker table too, somewhere I placed plans for building up a unit that can be operated by hand using bicycle chain drive [add a cordless drill and walk away for a few minutes] 

and if you are getting a really decent amount of blacksand, then how about using a gold screw? reverse helix..... http://www.goldscrew.com/ the one i used over the weekend seems like it picked out more gold and let more sands go and each pan i tried on the offal showed I was not losing any visible specks, and recovered a decent amount for the time 2 of us shoveled [we moved over a yard over bank material in about 3 hours] the only problem we faced was that the machine we were using was giving us a huge amount of garnet, but then so too did the Le trap sluice when we screen everything by hand, that area is just loaded with small garnet..... maybe i aught to sell it for sand blasting eh?

William
North Central Idaho


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## Seamus (Oct 1, 2008)

Blueduck,
I use a blue bowl for my final separation which seems to work best for me. It's just an idea that you might consider. Or not.


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## JustinNH (Oct 1, 2008)

Ive used a blue bowl before and I do not feel it is worth the price (but it is cool to watch 8) ).

We have some very very fine gold here in NH. Someone thought for sure I was throwing some out, but after saving all the stuff that comes out of the pan and he ran it through a blue bowl only to come up with two pieces that could barely be seen with a magnifying glass... and that was after a few hours of dredging 

Of course, the stuff the blue bowl gets is not what people refer to when they mention black sands holding gold, which are the specks you cannot see since they are either covered or bound up with the black sands.


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## Seamus (Oct 2, 2008)

The blue bowl is not for everyone. I do good with mine. It is really hard to set the flow just right to let the really small stuff sit there. If it's set right, then it can be as good as the wheel or a shaker table. I use a wheel also. I like both. I learned how to set it right last year and went through old sand again and pulled out a lot of stuff I missed the first time.

I have also put black sand in the bowl that was so course that it just sat there. The sand from that creek gets pulverized for sure.That's why I put it in question form if people have seen or considerd trying the bowl. Just an opinion from a west coast miner.


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## iis (Nov 3, 2008)

warlead said:


> So its coming up on the end of dredge season and I have concentrates sitting around in 5 gallon buckets. I usually run this through a clean up sluice and thats about it. I know there is more gold that I am just throwing away.
> I was wondering if I could take say a gallon of concentrates at a time and dump a couple gallon of AR into it, let it sit for a while (days?/week?) and then drop it out. Or is there a better easier way?
> 
> I have read the other black sands posts and I am not looking for something to recover the gold fast. I have a pole barn and just figure if I can fill buckets with AR and let sit outside to work their magic and go back in a week or so to drop and then heat in a cupple I would be good.
> ...


 :idea: 
Hi 
Do you trying: Le Trap Plastic SLUICE BOX river robber gold prospector
http://www.goldgold.com/cleanupfaster.htm


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## iis (Nov 3, 2008)

warlead said:


> So its coming up on the end of dredge season and I have concentrates sitting around in 5 gallon buckets. I usually run this through a clean up sluice and thats about it. I know there is more gold that I am just throwing away.
> I was wondering if I could take say a gallon of concentrates at a time and dump a couple gallon of AR into it, let it sit for a while (days?/week?) and then drop it out. Or is there a better easier way?
> 
> I have read the other black sands posts and I am not looking for something to recover the gold fast. I have a pole barn and just figure if I can fill buckets with AR and let sit outside to work their magic and go back in a week or so to drop and then heat in a cupple I would be good.
> ...


Hi 
Do you trying: Le Trap Plastic SLUICE BOX river robber gold prospector
http://www.goldgold.com/cleanupfaster.htm


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## lazersteve (Nov 3, 2008)

I've been too busy to get to it, but now that my Pt DVD is done I can move on to another project.

Steve


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## blueduck (Nov 4, 2008)

iis said:


> :idea:
> Hi
> Do you trying: Le Trap Plastic SLUICE BOX river robber gold prospector
> http://www.goldgold.com/cleanupfaster.htm



The river robber is an awesome unit and can recover the very fine material from a stream other sluices miss, the thing is easy to clean up and it will load up in the right material pretty fast.

To use it with recovered blacks from dredging, a person needs to use a ball mill and screen down to a uniform size, and then the gold will sit in the riffles as the blacks float awa, but if you have small or microscopic gold and larger chunks of blacks, your gold will float off before the blacks do....

the river robber would make an awesome sluice for a small recirculating setup, but needs fed at a constant rate, and slowly at that..... 

Angus Mackirk makes several smaller and larger sluices using the same principle, along with a few neat ideas for constant feeding.... and then the is a leach system for the garage that looks promising too..... A friend has one of his little beaver dredges and it recovers fines as well as the river robber by Le Trap does in a larger volume run.....

about as good as a product overview and review can get i hope. Yes the Le Trap is well worth having as a stream sluice and a cleanup riggin, but it needs a little work, like i am going to add a chuink of inner tube to act as a flair for increasing water intake in a small stream and reducing the unit from rising out or floating up [add a couple of rocks to the rubber and it aint going anywhere very fast] then it needs a rock bar to help kep the other end from rising in the water too..... over all it is a good unit for the cost..... and my 4 year old could pack it all day long and never complain if he wanted to, it is very light.

hope that helped. And a reverse helix is still the way to go.... Archimedes was right.

William
Idaho


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## ChucknC (Nov 8, 2008)

I'ved posted on this several times, but it bears rehashing.

I have several buckets full of prospecting concentes. I will be building a large ball mill and running the crushings thru a popandson cleanup sluice.
C
Similar to this setup:
http://www.youtube.com/watch?v=KdikUKNLCHY&NR=1

From there, you have 2 major choices in how to do the final recovery of the gold. You can use chemical or pyrological methods. I have had success both ways, but the cheapest to me are the pyro methods.

PM me and I'll fill in the details on what I have used.

Chuck


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