black sand clean up

M3R1IN

Full Member
Oct 6, 2006
167
1
Alberta, Canada
Detector(s) used
Whites DFX, stock and DD coil
I was out prospecting in Montana last weekend
and there was this old guy who just showed up and started sluicing upstream from me a ways
He seemed friendly so i decided to go chat with him
he gave me a lot of useful info and let me pick his brain about the local geography and different techniques
he saw that i had a large amount of black sand and said i should take some nitric acid to that and i would be amazed at how much gold would release from the lot. I explained that i am canadian and that nitric acid and mercury are very difficult to obtain here without a business licence
I am wondering on procedure for cleaning black sands with nitric acid and if anyone knows any industrial applications for nitric acid
whereby i could obtain it with less difficulty?
thanks
 

Upvote 0

Functional

Hero Member
Feb 16, 2007
512
3
Okanagan Valley, British Columbia, Canada
Detector(s) used
A Compass Magnum 420 recently brought back to life. And an untested "in the wild" Teknetics.
nebraskadad said:
FWIW, You all need to get a copy of the latest ICMJ magazine.. The "best suggestion" in the article comes down to one thing. Classify, CLASSify, CLASSIFY!!

You can classify from 12 mesh down to 30 mesh then 100 mesh use a magnet, then tumbler the blacksands in an acidic solution, then put in a bluebowl that is as good as it gets without playing with mercury.

Thanks for the input nebraskadad.

Personally I don't usually classify that much and when I do, its at the end of the day done over a tub, so I don't loose the black sands. We have small gold in the area I normally pan, mostly flakes and flour gold with pinhead sized platinum nuggets that are pretty easy to pick out when finish panning. Strangely enough I've never found any "flake" platinum. And of course are tellurides, (salts, like Calaverite), containing gold and platinum, (I think thats right, but I'm no chemist), mixed in with the black sand.

If you've got an idea of what your black sands contain, in most cases, you really don't need mercury. Small scale smelting isn't that hard if you have some basic equipment and can turn out some high grade gold cheaply. The basics on that are on these pages:

http://www.prospectorsparadise.com/html/smelting.html
http://www.prospectorsparadise.com/html/black_sand.html
http://www.prospectorsparadise.com/html/assaying.html
When you think you have assaying down, try colorimetric assay:
http://www.prospectorsparadise.com/html/colorimetric.html

Three things about the above website.
1) Your better off reading everything, as the pages aren't well ordered IMHO.
2) Follow all warnings when handling chemicals, (some of them can cause injury, or death).
3) If you must learn anything, make sure you learn about Acids and Bases on this page:
http://www.prospectorsparadise.com/html/acids.html

On the above page, there is an interesting comment about the use of nitric acid being used to clean up gold. Suffice to say, DON'T DO IT! At least not until you have read what it says about 3/4 of the way down the page under the section titled: "Things That You Can Use Acids and Bases For".

Further down the same page is a section titled: "Dealing with black sand" that should be of interest to all gold panners, but read the whole page so you know what concentrations of acid to use.

And lastly, while the site above refers to "Basement" Chemistry, I wouldn't do any of this stuff in a confined place.

F.
 

RetRmy

Jr. Member
Apr 17, 2007
28
0
I too heard about Nitric, but not for clean up, but for testing...to my understanding, it will "eat" fools gold but will do nothing to real gold.
I was able to get some at a jeweler, they use a knife sharpening stone to rub the ring across, then they put one drop of nitric on it to test to see if the jewelry is real or plate.The jeweler I went to had gone to the more advanced ultrasonic tester, so he sold me his old test kit.
But like others have said...be very careful, it can cause some serious injuries to your skin if you come in contact with it
 

wpareig

Greenie
Aug 15, 2007
16
0
Pennsylvania
I'm not as experienced in the chemical end as some who have responded, but, I'll tell you how I separate my ultra-fine gold from black sand.....

I bought plans for a roller mill that is about the size of a five gallon bucket (maybe a little bigger) that I run all my black sand through once I get all the gold out of it that I can..... I bought the plans on eBay and they claimed that it would reduce to about 600 mesh. In actuality it only reduced to just under 400 mesh, but since I have to use a microscope, that's small enough for me....

I bought a professional "sonic" jewelry cleaner on eBay for $80.00 and I put my black sand in it about 1/2 cup at a time (it holds a little over a cup and a half) and keep adding the crushed black sand every hour or so, letting the excess flow over (add by the table spoon into the center, as soon as it goes flat add another table spoon)...... The sizmic action keeps the heavies in the -400 mesh material moving to the bottem... I ran about 4 - 4 1/2 gallon of rich black sand and ended up seeing gold on top when I stopped. The gold actually filled the container......

The black sand that was left I proessed in a rock tumbler w/ about 1/4 oz. of mercury for about 2 hours / load (this is a 45lb. tumbler)... I heated the nitric acid in a pyrex dish and added the butten from the mercury press to it and after the smoke cleared I had hardly any gold...... I usually got a nice gold butten when processing with mercury and nitric acid.... What I found is that crushing your black sand below 400 mesh and using the sonic jewelry cleaner removed almost ALL gold in the black sand..... I probably would have had to run at least 50 gallon of black sand to even get a 1/4 oz. of gold after what the jewelry cleaner settled out....

What's in the jewelry cleaner isn't pure, there's still black sand (unless you keep adding until all you see is gold, but then I'm sure you would still have a tiny bit & you would loose gold in the overflow) plus other impurities like platnum, silver, copper, zinc etc., but it's as pure as you'll ever get it.....

That's just how I process mine, lots of other people on here have other great ideas that may work as well (I just don't use chemicals anymore, not worth it for what I miss)..... If I could get my roller mill to chush the material below 600 or 800 mesh I think I could get 100% (or close to it) of the micro gold with out chemicals...

Good luck and hope your pan is always lined in Gold....

Coyote....
 

OklaBuck

Greenie
Jan 28, 2007
15
3
McAlester, Okla
Detector(s) used
whites, Garrett.and Tesoro
Coyote... What model of ultra sonic cleaner are you useing. I have looked at several for sale on the net. And I would like to try one like you have. Buck
 

ChuckNC

Jr. Member
May 8, 2005
35
0
That ultrasonic jewelry cleaner is a good idea. Like Buck, I'd like to know what model you use so I can check it's results against my green bowl.

Here's a cheaper way to clean the blacksands instead of using nitric acid. Disolve plain uniodized salt in warm distilled vinager. Add the solution to the blacksands and agitate them periodicly. Does a great job of removing the free iron, zinc and other contaminants.

Another idea is plain bleach.


Chuck
 

wpareig

Greenie
Aug 15, 2007
16
0
Pennsylvania
wpareig said:
I'm not as experienced in the chemical end as some who have responded, but, I'll tell you how I separate my ultra-fine gold from black sand.....

I bought plans for a roller mill that is about the size of a five gallon bucket (maybe a little bigger) that I run all my black sand through once I get all the gold out of it that I can..... I bought the plans on eBay and they claimed that it would reduce to about 600 mesh. In actuality it only reduced to just under 400 mesh, but since I have to use a microscope, that's small enough for me....

I bought a professional "sonic" jewelry cleaner on eBay for $80.00 and I put my black sand in it about 1/2 cup at a time (it holds a little over a cup and a half) and keep adding the crushed black sand every hour or so, letting the excess flow over (add by the table spoon into the center, as soon as it goes flat add another table spoon)...... The sizmic action keeps the heavies in the -400 mesh material moving to the bottem... I ran about 4 - 4 1/2 gallon of rich black sand and ended up seeing gold on top when I stopped. The gold actually filled the container......

The black sand that was left I proessed in a rock tumbler w/ about 1/4 oz. of mercury for about 2 hours / load (this is a 45lb. tumbler)... I heated the nitric acid in a pyrex dish and added the butten from the mercury press to it and after the smoke cleared I had hardly any gold...... I usually got a nice gold butten when processing with mercury and nitric acid.... What I found is that crushing your black sand below 400 mesh and using the sonic jewelry cleaner removed almost ALL gold in the black sand..... I probably would have had to run at least 50 gallon of black sand to even get a 1/4 oz. of gold after what the jewelry cleaner settled out....

What's in the jewelry cleaner isn't pure, there's still black sand (unless you keep adding until all you see is gold, but then I'm sure you would still have a tiny bit & you would loose gold in the overflow) plus other impurities like platnum, silver, copper, zinc etc., but it's as pure as you'll ever get it.....

That's just how I process mine, lots of other people on here have other great ideas that may work as well (I just don't use chemicals anymore, not worth it for what I miss)..... If I could get my roller mill to chush the material below 600 or 800 mesh I think I could get 100% (or close to it) of the micro gold with out chemicals...

Good luck and hope your pan is always lined in Gold....

Coyote....

I'm sorry, I haven't been on in a while. I noticed a few PM's and question as to the type of Ultra sonic cleaner I use..........

I use 2 models, both for the same reason.... De Gassing Properties. I had been using the one I got from ebay & found the company had a model that worked even better for me.... Both not only de-gas but both have very controlled heating properties (for some reason I get better recovery from the heated solution than running cold....

They are (my favorite) the Elmasonic S in Autodegas / degasing mode @ 37khz & 65o C. on sweep / degas and the x-tra 70 H at a frequency of 5.6 A and temp of around 65 C. on continious....
 

gedfire

Greenie
Sep 22, 2008
19
0
Great post! What model did you find that worked best for you? Or did you already mention it in your last post?
 

EE THr

Silver Member
Apr 21, 2008
3,979
38
Central California
Different acids have different "personalities." If you are using hydrochloric acid, also called HCl (that's a lower case "L" on the end), or muriatic acid (which is usually 31%, and just right for most uses); you can get a filter mask for it at Lowe's or Home Depot.

One problem with nitric acid is there is nothing which will filter it.

Both hydrochloric and nitric produce lots of fumes. Usually you can actually see them when opening a container or pouring them (always use rubber gloves and eye protection, in case of splashes or accidents. You cannot pour them without some splashing, even tiny amounts you wouldn't normally notice when pouring other liquids). Don't get these fumes up your snoot! It can make you jerk back and possibly drop whatever you are holding, or stumble and spill stuff.

Ongoing breathing of dissipated fumes from these acids is not good, it can burn your lungs.

If you are just using a little bit of it, work outside with a wind at your back.

If you are regularly processing stuff with them, you will probably want to work indoors. You need a strong exhaust fan in the wall to the outside, and a way for fresh air to get in, on the opposite side of the room. The fumes will rust or corrode any metal objects nearby---tools, etc. Work with your back to the fresh air. Better yet, build a "fume hood," which has a strong fan, with filters, and is PVC pipe (4" diameter) vented to above the roof. Google it for ideas.

Sulfuric acid has a very high boiling point, so there are hardly any fumes at all. It can even be mistaken for water (label everything!) While the other two acids mentioned above may be rinsed off with water without much harm to your skin, sulfuric will bore down into your flesh, because it seeks water. Especially concentrated sulfuric (car battery acid is only about 33%). And most especially HOT concentrated sulfuric, as is produced with some methods for making your own nitric.

It's a very good idea to read several different safety recommendations for each acid, before using them.
 

CharlieBitMe

Greenie
Apr 22, 2010
16
1
Another method that I've read about and that seems safe because it uses household chemicals, is halide leaching. However, the few sites out there that talk about it do not provide sufficient detail -- i.e. step by step details with photos for each step.

Lowe's carries concentrated bleach, which if I recall correctly is 5x more concentrated than the average household bleach. I'll stir the bucket (half full with black sand) once a day and leave the bleach in there to leach all the gold for a week. My specific question is, after transferring the bleach, which now contains the dissolved gold to a new container, what is the easiest way to precipitate out the gold?

My concentrates have plenty of black sand crystals, which are brownish in color. If that's tellurite, do I need to crush them to dust in order for the bleach to dissolve the gold?
 

Astrobouncer

Hero Member
Jun 21, 2009
823
343
This is an interesting thread, but this quote here:

Wallace J said:
Out of a ten pound jar [of black sand] we got three pounds of gold.

I have a little trouble believing that. But still good info in here nonetheless.
 

enamel7

Gold Member
Apr 16, 2005
6,384
2,546
North Carolina
Detector(s) used
Garrett AT Gold
Primary Interest:
All Treasure Hunting
Astrobouncer said:
This is an interesting thread, but this quote here:

Wallace J said:
Out of a ten pound jar [of black sand] we got three pounds of gold.

I have a little trouble believing that. But still good info in here nonetheless.
I can believe it Astro. In some areas of Cali I here that on average 4 out of every 10 grains of black sand is encrusted gold. One reason I NEVER throw anything away.
Heavy pans,
enamel7
 

Astrobouncer

Hero Member
Jun 21, 2009
823
343
That's pretty amazing. I always keep my cons too, for when I get a ball mill or something to grind them down with.
 

kuger

Gold Member
Nov 6, 2007
9,721
2,794
Detector(s) used
,M.X.T.& Tesoro Tejon
Primary Interest:
All Treasure Hunting
I have 10 five gallon buckets of Black sand if anybody would like to buy some,$1.00 a pound plus shipping.All dredge cons panned and spiral wheeled once
 

Traveller

Jr. Member
Sep 22, 2010
26
1
wpareig
Interesting method you have evolved for separating gold from black sand via an ultrasonic jewellery cleaner.
I had an idea similar to this that was inspired by a conversation I had with an oldtimer here.
I live on the north coast of British Columbia, Canada. On a very remote section of storm washed beach here, there are deposits of black sand twenty feet wide, 12" thick and miles long. Assays have shown this placer to be very rich in gold but the gold is microscopic and of a flaky nature and seems to defy most gravity separation methods.
I was told that, in the Depression years, many small miners would pack this pure black sand out on packhorses and attempt recovery of gold back at their homesteads. Considering the high density of black sand, the assays on the placer, and the price of gold in the 1930's, this did not seem credible. On the other hand, my grandfather shovelled coal for ten cents a ton in the Depression. Hmmmm....must have been tough sob's in those days.
According to the oldtimer I spoke to (who was a boy during the Depression), a simple method was devised to concentrate the placer on site to much more manageable volumes.
It consisted, believe it or not, of simply putting black sand and an equal volume of water in a bucket and slamming the bottom of the bucket down on a plank, log or flat rock. Following this, 90% of the top of the black sand in the bucket was removed and more added. Many buckets of black sand could be reduced this way to possibly a couple of quarts of rich concentrate.
I thought of expanding on this idea by using a small concrete compactor; the sort used to compact concrete in building foundation forms. It would be somewhat rougher than your idea but would be capable of higher throughput volumes.
A couple of questions:
1. Does the frequency of vibration seem to make any difference? I can visualize the wrong frequency floating gold to the surface instead of sending it to the bottom LOL.
2. What exactly is Degassing anyways? You mentioned you were impressed with the Degassing Peoperties of the ultrasonic jewellery cleaners you had purchased. I've heard the term before but have no clue as to its meaning.
3. Have you ever considered using citric acid or a salt roast over a hot fire to break down the oxides and allow access to micron gold beneath it?
As I stated, the placer I am looking at is very rich and in a very remote location. It may not be economical to attempt anything but separation of free gold from the black sand. However, I think it would be worth testing, using your methods, to see if there are hidden values in the black sand that might be processed on site.
Regards
Bob
 

Gold_Striker

Full Member
Sep 27, 2010
105
5
Denver,CO
Detector(s) used
xterra 705 by minelab
Primary Interest:
Prospecting
:laughing9: This is amazing 3 pounds wow! Every prospector should know about this, I wonder how many people are unaware they are throwing tons of gold back into the sources they got it from.
:icon_thumright:
 

gedfire

Greenie
Sep 22, 2008
19
0
I am seeing wpareig method as something I would like to try.If it works as well as wpareig suggests,then I may be better off buying an ultrasonic cleaner than the wave tables by action mining for small scale work.The idea of different frequencies,particle size seem worth exploring.I looked at the machines at the company's website and they have quite a variety.Small to large volume versions.Wpareig, you are unto something here.But I just need to explore the possibilities.Based on the website, frequency MATTERS.So the more recent versions offer multifrequency options as well as heat.Seem kinda analogous to metal detecting were your 14kHz MXT versus the Gbugs 71 kHz and sensitivity to smaller gold.Interesting potential here.If anyone else have explored this practise,please let us know.
 

homefires

Hero Member
May 20, 2008
526
15
deming n.m.
Detector(s) used
Any thing Available within 50ft
You Need one of these!

You Fill it, Run it, Fill it Run it, Dump top half, Fill it Run it. Repeat a bunch of times and then Pan the bottom 1/8th.

Mini-Cement-Mixer-HY-PCM-06-.jpg


Run it strait up!
 

Traveller

Jr. Member
Sep 22, 2010
26
1
gedfire

There is a new product on the market called the Quicksand Concentrator. Check out their website at www.gotnuggets.com.

I phoned their shop in California this afternoon and had a long chat with the inventor of this unit. It sells for $60, requires no power, is not much bigger than a loaf of bread and requires only water pressure from a pump. They sell a 500 GPH 12 volt pump to supply water to it for another $30.

According to its inventor, this unit works on the fluidized bed principle. Ore or placer material, be it bank run, crushed ore or black sand, need only be screened to 8 mesh (1/8") and can be fed into this unit at a virtually unlimited rate. Water is fed by hose into the bottom of the unit, fluidizing the bed, and the process separates denser material via liquefaction. He feels this unit could make sluicing, panning, etc. obselete.

I suggested a vibrator might make this work better but he claimed the water alone worked just fine.

He also said he had a customer who grinds his black sand to -200 mesh and successfully uses this unit to recover PM's from the -200 mesh material. That alone is a rather remarkable feat, I daresay.


I plan to purchase one of these.

Regards

Bob
 

gedfire

Greenie
Sep 22, 2008
19
0
Homefires and Bob,

Thanks homefire and Bob, great suggestions.Incidentally,the day I made this post I looked for different types of electric cement mixers.Homefires, throwing a few river stones or steel balls in the should help eh? I am elated that technology has come so far as to allow for efficient recovery at lower cost to the small scale miner.

Bob loved the description of the device.Seem to be a mini elutriation tower.I like the fine gold recovery potential.Hope I can get some testimonials from users of the device.

regards,
Ged
 

Traveller

Jr. Member
Sep 22, 2010
26
1
Ged
No, this is most definitely not an elutriation tower. The inventor was quite emphatic about that point. This unit works on the principle of liquefaction; ie. liquefying a mass of media and letting its fluidized bed separate by density.
E-towers are rather finicky devices and can only be fed at a very restricted rate. He claims the feed rate on this unit is virtually unlimited.
He also said he is currently developing a unit based on a container in the five gallon bucket range and hopes to be marketing it soon.
Regards
Bob
 

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