# Beautiful Gold Precipitate!



## philddreamer (Jul 6, 2012)

I've been processing some pins thru the sulphuric cell and after decanting, I just add HCl-clorox & digest the sludge.
I follow with heating the solution to evaporate the clorox; maybe I didn't get rid of all the clorox, so after adding the SMB and having no reaction, I applied heat to the solution just to have a beautiful "drop" of golden crystals. I've done this 4 times now on purpose just see if I would have the same results... the pic's show the gold crystals.
My question, why do I get gold crystals from a dirty solution after adding SMB. It looks like dropping gold with oxilic acid.

Thank you!

Phil


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## Harold_V (Jul 6, 2012)

Phil,
I had that experience, at the most, maybe three times in all the years I refined. I have no idea why it occurs, but found it to be one of the prettiest things I ever witnessed. Certainly on par with precipitating a large volume of platinum from solution, using ammonium chloride!

My experiences all came randomly, and all when I was precipitating gold that was being refined a second time. Each was from a large volume of concentrated solution (near five ounces/liter). I was never able to reproduce that reaction intentionally. In my case, my solution was iced, with no heat added. The only noticeable difference was that the solution would absorb SO2 without showing a sign of precipitation, then, as it lightened in color, the entire volume would suddenly flash to something resembling bronze paint. As my solution was virtually free of contamination, there was no green hue. 

Thanks for sharing. Sure brought back some fond memories.

Harold


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## goldsilverpro (Jul 6, 2012)

Like Harold, I only had that happen a few times while doing normal refining and, when it happened, it was always a pleasant surprise. About 40+ years ago, when I was young, foolish, and fearless, I found that I could create it at will by adding some acetone to a fairly concentrated AR gold solution and then dropping the gold with an EDTA variation. I dipped a glass slide into the swirling gold solution and some of the crystals stuck to the slide. After they air dried, I looked at them under a B&L metallograph, probably at about 500-1000X. They appeared as individual brilliant perfectly shaped hexagons and triangles, of different sizes, which were seemingly flat. The reflection from them was almost blinding under the scope.

I did this only a couple of times, due to the evil smell this mixture produced. I have no idea what I was making and whether or not it was toxic or potentially explosive - probably both. This post is for interest only. I would hope that no one tries to repeat it.

I've always thought that, if one could do this safely and predictably, the crystalline powder might be sold at a premium. If 9999 pure, I think it could be used to make gold thick film paste used for conductive traces on hybrid circuits. Due to their shape, the crystals would seem to stack flat. This would increase the packing density and, thus, increase the electrical conductivity of the fired on traces. At present, paste manufacturers, such as DuPont, have developed high purity PM spherical powders of random diameters (increases the packing density) for this purpose.


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## Palladium (Jul 6, 2012)

Now that is cool! Haven't had that one happen yet.


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## philddreamer (Jul 6, 2012)

Thank you gentlemen! 

I'm getting ready to try it for the fifth time... If I get the same results, maybe its the presence of some kovar in the sulphuric, thus cementing the gold?

Phil


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## Palladium (Jul 6, 2012)

Can you film it? I would like to try it as an experiment. I've even got a 600x scope. I would like to try what Chris did to. Document your notes for us please. Seems you got a decent understanding of it if you have done it 4 times.


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## philddreamer (Jul 6, 2012)

I'll try filming it...
Now, I believe that the pins have kovar or nickle over copper; they are a bit magnetic. The yield is a constant 4 grams per pound. I did the very first batch in nitric to test and figure the yield, but over a galon of nitric was needed to complete the process; so nitric is out of the question. The second pound went into AP; about 3 galons and more than 2 weeks later I had to finish it thru P-AR. Pretty messy!
So, I decided the sulphuric cell. This method is working very good, but I don't like the time of diluting & boiling galons of dilute sulphuric, so I vacuum filter most of the solution thru fiber glass. Then I run some HCl/Cl thru the filter & recover the gold & re-use the filter; then add this to the main pot with the sludge.
There's about a good couple fluid ounces of sulphuric left with the sludge. To this I add some more HCl/Cl and the water from my rinses. I apply some heat until the solution turns clear green. Let cool a bit; filter & proceed to add dry SMB. I've used some extrra Clorox, so I don't thick I've been evaporating ALL the clorox. The reason I believe so is that, when I add the SMB there's no imediate reaction; so after 3 or 4 minutes and no precipitate, I apply heat to the solution. A few minutes later, as the solution has warmed up, WALLA! This has happened 4 times in a row, so now is the 5th time, with the same material & proceedures. We'll see if it happens again. 
Mind you, the solution is dirty, so, I just wonder if the presence of some of the base metals, (mainly kovar, iron or nickle), plus the addition of the SMB, is cementing, maybe, the gold. I'm puzzled!

Thanks for the interest; I hope we can find an answer.

Phil
I don't know how pure this gold is neither. I was going to re-desolve it, but I'll continue to save it, melt it & ship next week to my assayer & find out how pure is it indeed.


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## samuel-a (Jul 6, 2012)

Hi Phil

That's cool indeed! Thanks.

Could you take a picture of the dry powder before you melt it?


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## BAMGOLD (Jul 6, 2012)

I asked my wife what the first picture looked like, she said "hamburger bun" :mrgreen:


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## philddreamer (Jul 6, 2012)

Sorry, but this time it was a standard "drop"... 
Did I do anything different this time? Yes. This time I used less HCl/Cl, & had less solution, 600ml, for the same gold expected. After adding the dry SMB and stiring for about 30 seconds the solution turned brown & the gold dropped out of solution.
In the previous I had more solution 1000ml + because of the rinse water. There was also more HCl & clorox than required for the gold expected. After adding the SMB & stiring for more than 3 or 4 minutes, no reaction at all, so I let it sit. 5 minutes later I came to check it, & the solution was turning golden with the gold crystals; I then placed it on the hotplate and as soon as it started to heat up, the beautiful crystals started to form in mass.

There will be more of the same material processed in the following days, hopefuly I'll repeat the crystals. 8) 

Phil


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## Lou (Jul 7, 2012)

I'm pretty sure it is the Chlorox. This formation seems to be pH sensitive.


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## lazersteve (Jul 7, 2012)

We have discussed this phenomenon a few times, I personally think it was the salt (sodium chloride) concentration of the solution, but I could be wrong. As Lou stated the salt concentration would be related to the amount of clorox used in the process.

My reasoning is based upon an organic chemistry technique of promoting crystallization known as 'salting out'.

Here' the old topic:

Glittering Gold Precipitate

Steve


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## Lou (Jul 7, 2012)

Would it be helpful to discuss the mechanics of producing a precipitate?

Phenomena like these are explainable and growing a good, high purity gold precipitate is something that is achievable even from dirty solutions.


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## samuel-a (Jul 7, 2012)

Yes Lou, this very interesting subject.

In this very moment, i'm trying to replicate Phil's results.


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## philddreamer (Jul 7, 2012)

Thanks Lou & Steve!
Then its seems that what I first suspected, the excess clorox, is the culprit. And that's why this last time, aftter using much less HCl/clorox, I had a quick drop of brown gold. 

Like Samuel, I have another batch ready to be filtered and run thru HCl/Cl. 
I'll do another test. I'll filter the solution after dissolving the sludge, then add the dry SMB and then apply some heat. Maybe we can skip the first application of heat!? We'll see...

Sam, please let us know your results.

Thanks!
Phil


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## samuel-a (Jul 7, 2012)

Phil, No success unfortunately.

There's too much information missing at the moment, so my little experience was very crude.
pH, gold concentration, how much HCl, how much chlorox, how much sulfuric acid and more...


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## samuel-a (Jul 7, 2012)

There are many variables to consider.

Hopefully, we could barin storm this concept and eventually come up with some way to precipitate gold in the form and size of sea sand grains form slightly dirty gold solutions...
For sake of science, I don't mind trying whatever suggested...


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## philddreamer (Jul 7, 2012)

I'm heading out back to filter & process a small batch. I'll keep track of the procedure; If it works I'll post the steps.


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## Palladium (Jul 7, 2012)

Not what we are talking about but cool.

[youtube]http://www.youtube.com/watch?v=G8qnaq6Ehc8[/youtube]


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## maynman1751 (Jul 7, 2012)

Too Cool Palladium! 8) Beats the heck out of a snow globe.


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## philddreamer (Jul 7, 2012)

I was able to do it again, but it was not as impressive... It was from the same pins that where run thru AP. After dissolving the gold foils, I filtered and added a bit more clorox. Followed by adding dry SMB and lots of stirring. After about 3 minutes it started to precipitate, but it didn't swirl, even after placeing it on the hot plate. Also, the gold settled pretty fast. The gold was very fine.
So, I wonder if some sulphuric is needed. I observed while applying heat to a coffee pot with sulphuric the same swirling effect of the fine particles of the sludge and it resembles the same as the gold crystals... maybe some sulphuric is called for. I'll be processing some sludge tomorrow.

Phil


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## samuel-a (Jul 7, 2012)

Phil, thanks for the update.

The key obsevation here is, that something inhibits co-rduction/mechanical drag of other elements.

Perhaps it's got somthing to do with the overall orp, i'm basing that upon my experiance with concentrated gold solutions (dirty solutions).
At first, when you add smb to the solution, extreemly light tan gold powder is precipitated inidacting high purity. The dirtiest gold is precipitated last and is usually black.
There seems to be a threshold, where just a gram or two (per liter) is left in the solution, that's when co-precipitation occur. You are doing somthing that eliminates this (assuming you precipitate 100% of the gold).


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## philddreamer (Jul 8, 2012)

Hi Sam!
I believe I'm precipitaing almost all gold. The stannous test is negative. We'll see when I cement the values from the stock pot.
I took some pic's of the gold, but they didn't have much resolution.
The results from the first expirience, I shipped already last week. 
The second is from some 15g of material a friend brought, but it was mainly base metals. The result, though, nice.
The third, was 3.5g and it looked nice and shinny, but settled too fast.
The fourth, also 3.5g and the crystals swirled suspended for a while. Very nice!
The 5th, shinny but settled too fast.

Phil


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## Lou (Jul 8, 2012)

samuel-a said:


> Phil, thanks for the update.
> 
> The key obsevation here is, that something inhibits co-rduction/mechanical drag of other elements.
> 
> ...





I kind of got into it on this one: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=84&t=6544&p=89773&hilit=nucleation#p89773

The dirtiest gold is always precipitated last, and the finest always first. The lower the concentration of reductant and the slower its introduction and action (read, the colder the solution), the slower the growth of the gold sponge, the blonder and more open the pore structure will be to rinsing out entrapped ions. There is a big difference between occlusions/entrapment in the hydration layer of adsorbed ions and co-reduction (which will happen with the ORP is such that other things are co-mingled, i.e. Te or Pd). 

The precipitation of gold can be tackled by statistical mechanics--if [Au{+3}] is high relative (think 10^4) to [Cu{+2}], [Ag{+}] etc, then it will only make sense that the precipitate first formed will be more likely to be composed of more gold atoms than other atoms that are entrained by attrition, as the great likilihood of occlusion into the precipitate should be toward the end when the gold is almost quantitatively reduced and is approaching equimolar concentration with the impurities. It isn't necessarily a selectivity problem, it's more of a problem with nucleation and growth.

If I have time tomorrow, I will hit my books and think about this and write more. It's an interesting thing! We will model it soon.


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## philddreamer (Jul 8, 2012)

I was able to repeat it again today. After doing to batches before this last, (one from an AP, another from an AR), this one is from the sulphuric cell. Like the previous nice result, I let sulphuric, (but not as much as in the previous), and I was able to duplicate the results. I believe that the sulphuric has something to do with the crystalization... I could be wrong, though.. My next batch will contain more sulphuric.
The AP & AR drops were light in color, but the gold settled real fast. With the sulphuric, it tends to "hang" in the solution.
This time I had about half less sulphuric, so it settled faster, but not so fast. 
I have a video, but I'm having problems posting it... :roll: 

Phil


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## samuel-a (Jul 9, 2012)

This is truly fascinating Lou.

Not being a true chemist (and english speaker) my self, it's hard for me to put thoughts on paper. So all i can say is thank you, it confirms my initial intuition and you are describing this far better then anyone else could.


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## Anonymous (Jul 9, 2012)

BAMGOLD said:


> I asked my wife what the first picture looked like, she said "hamburger bun" :mrgreen:


There is no doubt that the first picture looks like the top of a hamburger bun.. :lol: ..... it really does.

Kevin


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## HAuCl4 (Jul 10, 2012)

A leprechaun once told me that having base metal sulphates instead of chlorides always produced cleaner precipitations of gold. Maybe that explains part of what's happening here. Copper sulphate is much more soluble and stable than the chlorides and does not react with SMB. Maybe the trick to duplicate the experiment is to add just enough sulphuric acid, but not too much?. 

The big crystals growth remain a mistery though, even for the leprechaun.:shock:


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## philddreamer (Jul 10, 2012)

By George, I think I've got it!!! :shock: The video, that is... :roll: 

http://www.youtube.com/watch?v=SocUsIajD4M

Phil


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## lazersteve (Jul 10, 2012)

Phil,

Under what reaction conditions did you manage to recreate the crystallization?

Steve


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## philddreamer (Jul 10, 2012)

Steve, forgive me, but I'll try to explain it the best I can. I have no chemistry background.

After decanting most of the sulphuric acid from the cell, I left some 150ml + of sulphuric with the sludge, and washed the sludge & sulphuric into my coffee pot.
Then I added about 100ml of HCl, and started to add clorox in small increments, until all the gold dissolved. Then I added a bit more clorox. I had about 900ml of solution, so the rest was added water & from the rinsing.
I heated the solution for about half an hour; the solution turned from a milky green to a clear emerald green.
I filtered the solution, and while it was still warm, I added a some small amount of SMB. I stirred and continue to add SMB slowly.
After 10 min. there was no reaction, so I started to add more SMB; I fumbled and dropped about 5g.. The gold immediatley started dropping out and as I stirred the solution, the crystals appeared. So I set it on the hotplate so to get the "up draft" effect, but the gold settled too fast.

I think the sulphuric has also something to do with it. Tomorrow I'll be running another batch. To this one I'll add a bit more sulphuric and hope to recreate the original effect. 
I tried to recreate it from an AP & an AR processes, but no swirling crystals.

I hope I was able to explain it okay...
Phil


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## ericrm (Jul 10, 2012)

phil
this is realy an interesting phenomenon
do you mind a few question?

is ALL your gold in crystal form?
do you manadge to remove 100% of your gold from solution in one shot?
have you tested a small quantity of gold crystal to see if the purity was in the 999 like the silver crystal?
when DRY do those crystal act like sand or do they clump weardly togeter?
what are the size of the crysrtal?
do they sink fast leaving a crystal clear dirty solution behind?

sorry for all the question but you may have opened a new refining way on grf 8)


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## philddreamer (Jul 11, 2012)

Hi Reic!
I don't know if I opened a new way of refining, but it may be an interesting way for precipitating gold from a dirty solution. I'm still working out the "bugs"! I really don't know nor understand what's going on. I have no chemistry background either. It just happened... and Ive been able to recreate it. I hope I can do it again tomorrow.


> is ALL your gold in crystal form?


As far as I can tell, yes.


> do you manadge to remove 100% of your gold from solution in one shot?


Well, if one shot means without having to add more SMB, yes. I stannous test and its negative. Any traces I'll get later from the stock pot.


> have you tested a small quantity of gold crystal to see if the purity was in the 999 like the silver crystal?


I'm sending 15g to my assayer in the next day or two, he'll let us know how clean it really is. I think it still could use a second refining for .999. After all, the solution is dirty.


> when DRY do those crystal act like sand or do they clump weardly togeter?


The pic's posted earlier show the difference in the dry gold powder. Number 1 and number 3, the gold was fluffy, like pop corn, and it looks more than there really is. Number 2, the gold rolled like cinnamon sticks an it's harder. There's 3.5g on each of pic's #2 & #3.


> what are the size of the crysrtal?


The crystals on pic's 1 and 3 were a bit bigger and tended to stay separate. Number 2, the crystals were much smaller.


> do they sink fast leaving a crystal clear dirty solution behind?


They settle pretty fast, but the solution is not clear until the next morning. I vacuum filtered one of the solutions after a few hours and very fine gold was on the filter.
I hope I was able to answer your Q's...
Thanks for the interest!
Phil


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## ericrm (Jul 11, 2012)

thank you for the complete answer,it is apreciated


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## philddreamer (Jul 11, 2012)

You're welcome, Eric.

I would like to post some pic's of what "things" look like when I've done the process. I didn't post any pic's before because of problems with the camera, and time. I'm up to my arm pits in batches, home chores & helping some buyers, that there's not enough time in the day... Mine is a small scale hobby that keeps me from boredom, but still it's time consumie.

Thanks for your interest & I hope the pic's helps.
Phil


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## Lobby (Jul 11, 2012)

I've often wondered why gold, dropped from pretty much any solution - with name your precipitant, always looks orange / brown. Yet after cleaning and melting, it has the characteristic gold metallic color. 

Might what Phil be observing be some sort of bypassing of the orange / brown gold phase, and instead proceeding directly into a metallic crystal?


Or, am I dense and are you more chemist types already heading down this path? :mrgreen:


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## philddreamer (Jul 13, 2012)

I recovered 31g. The gold assayed at .990. Not bad from a dirty solution. I did 3 boils in water; one in HCl; 3 in water. Dried & melted. 

Phil


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## Harold_V (Jul 14, 2012)

Lobby said:


> I've often wondered why gold, dropped from pretty much any solution - with name your precipitant, always looks orange / brown. Yet after cleaning and melting, it has the characteristic gold metallic color.


Simple. Because precipitated gold is finely divided, it reflects light in a myriad of directions. All that is required for the cinnamon colored gold to display the familiar luster and color with which you're familiar is to abrade the surface. Place a small amount on the back side of a spot plate, then run a porcelain spatula across the material, pressing hard. Tell me what you see. 



> Might what Phil be observing be some sort of bypassing of the orange / brown gold phase, and instead proceeding directly into a metallic crystal?


It is my opinion that what Phil accomplished was to precipitate gold in a crystalline configuration, which offers faceted surfaces in lieu of the random surfaces of the powder one normally accomplishes. The facets reflect light in a line instead of randomly, as does the powder. I drew that conclusion long ago, when I, too, managed to precipitate similar gold. Big difference is, I was never able to repeat the process on demand, while Phil has. In my case, it happened about three times, over years of refining. I had no explanation for the results I achieved. 

My hat is off to Phil, who appears to have determined why it happens. 

Harold


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## philddreamer (Jul 14, 2012)

I thank you Harold!  
And thanks to all the other experts in this great Forum! It's been the knowledge shared that has made this posible. 
The precipitaion is very clean gold, but not always does it "hang" swirling; but then agian, the purity is what matters, especially coming out of a dirty solution.

This last batch, #8, the gold started to precipitate slowly at the very top and it stayed at the top. I got a bit desperate & added some more SMB, and then it dropped and settled righ away. Within 3 hrs. the solution was clear & I was able to filter.

Phil


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## HAuCl4 (Jul 15, 2012)

Hi Phild. Nice photos and process!. 8) 

If you have a small batch one day and you feel adventurous, try this:

1-After you are done with the HCL-Clorox treatment to your batch that has a good but not too big amount of sulphuric acid, and *before* adding any SMB:
a-Add dropwise a very concentrated amount of lye (NaOH) or KOH. Some drain cleaners are basically that. Stirring all the time.
b-Keep adding dropwise till pH is 6 or 6.5 (pH test strips are cheap!).
c-Filter the precipitates out.
d-Add a little fresh clorox and fresh HCl.
e-Do your SMB thingy.

2-Post your pictures of most likely 99999 or 999999 gold. :shock:


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## goldenchild (Jul 15, 2012)

HAuCl4 said:


> Hi Phild. Nice photos and process!. 8)
> 
> If you have a small batch one day and you feel adventurous, try this:
> 
> ...



This sounds a bit like the AgCl method. When you say to add the NaOH, is it to a once refined or twice refined solution? What will be precipitated out? The base metals or the gold? Seems that everything would drop out. After filtering are you adding the HCL/Clorox to the left over solution or to the ppt?


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## HAuCl4 (Jul 15, 2012)

Sorry if what I posted wasn't clear.

1-After the first HCl-Clorox that Phild does to a solution, one must filter the solution as Phild does. Most of the silver will be here in the solids.
2-Then to the clear, filtered solution, you add concentrated lye dropwise, stirring all the time, till pH is ~6-6.5
3-Then you let it settle, and filter OUT the hydroxides formed (mostly of copper and other base metals).
4-Then acidify the clear solution with HCl-clorox, and a few drops of sulphuric acid. The solution must be completely clear and yellow orange at this stage, if not, filter again.
5-Then the SMB like Phild does.


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## goldenchild (Jul 15, 2012)

I understand now. But wont gold also drop out of solution when adding NaOH?


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## philddreamer (Jul 17, 2012)

This is a short video of batch #8
[youtube]http://www.youtube.com/watch?v=9kLrF2iO4GQ[/youtube]
I added the dry SMB very slowly and the gold started to precipitate about 10 minutes later. The gold started to precipitate at the top... :shock: ; then I added a bit more SMB & the gold just dropped; and settled within 3 hours.
Phil

P.S. Thanks Mario for teaching me how to post the videos! 8)


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## HAuCl4 (Jul 18, 2012)

goldenchild said:


> I understand now. But wont gold also drop out of solution when adding NaOH?


Add slowly, agitate well and keep pH below 6.5, and it should work quite well.


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## 4metals (Jul 18, 2012)

Is this armchair theory or experience, in any event you're throwing those 9's out quite freely! I understand your concept but metals like copper, zinc and nickel do not drop below 0.001 mg/l until the pH is 9. Their solubility at 6 is over 10 mg/l.

I do know that gold comes out of waste solution and is collected with the hydroxides at pH 9.5, if you get any metals dropping at pH<6.5 I doubt it will be enough to exceed even .999 on your final product.


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## HAuCl4 (Jul 19, 2012)

Experience is that most base metals and silver drop out at around 6.5
Idea is to get what is left in contaminants as sulphates (copper mainly), so that when SMB or SO2 is applied, there's less copper contamination.
If no PGMs are present at all (as should be with this feed material), 5N is the norm with good rinsing and washing. :shock:


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## goldenchild (Jul 19, 2012)

HAuCl4,

Would you be willing to make a video demonstrating this?


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## HAuCl4 (Jul 20, 2012)

goldenchild said:


> HAuCl4,
> 
> Would you be willing to make a video demonstrating this?


No. But you have my permission to do so, if you want. :lol:


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