# Salt in Acid



## chawimac (Feb 26, 2012)

I am stuck in a process and need some insight. 

I am processing a material that is 8k gold and the rest silver. It is from a mine, but I made sure there were no contaminates like lead or mercury. I analyzed the sample myself and it is pure gold and silver. 

I made the material into shot form and took 125 grams of it and boiled it in 275 ml of nitric and 275 ml of distilled water. After about an hour boil I let it set overnight. I have attached pictures of what happens.

I am wondering why my material is covered in salt? I drained the acid to be processed to remove the silver. I boiled in distilled water twice the original material. Most of the salt remains.

What am I doing wrong?

I gave up on the salt and processed the remainder of the material with AR. Much gold dissolves but only makes it up to about 92% purity. A gray porous material remains, much like that of scrap jewelry that gets the typical silver protective layer. When I melted this material, its about 47% gold and 53% silver.

I am very new to this, though I had the AR process down. Inquarting isn't quite working out for me. 

Any thoughts?

Oh BTW, I have a Fischer XAN120 XRF for my assay. So yes I got a very good idea of what I am looking at.


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## lazersteve (Feb 26, 2012)

What was your source of nitric acid (homemade, technical, ACS, etc.) ?

Did you inquart to 25% gold (6 kt) using known purity silver before going with diluted nitric acid?

Is your XRF properly calibrated to detect the various base and precious metals?

Has the ore been crushed and roasted?

Silver chloride is purple to the point of almost being black when it forms the protective coating on improperly inquarted gold. The colors I'm seeing (drab green and white) are indicating a base metal is present in my opinion. 

XRF will not indicate sulfides, chlorides, and other compounds which can cause odd behaviour with nitric acid. 


Steve


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## chawimac (Feb 26, 2012)

The Nitric was technical grade. Don't have on hand the exact % but its from an chemistry supply place.

I did not inquart. Like I said, it is from a mine and occurs naturally at 8k gold and the rest silver.

The XRF is well calibrated, and is a very high end machine.

The material was in a bar when I received it (no ore to crush) and then I melted it and made it into shot form so I doubt anything made it past the melting...

The pictures are pretty true to the eye so what you see in the pics is what I see.

Is this a contaminant problem or the inquating not being 6k? Will having 8k gold produce these salts? Where do the salts come from and should I be concerned? Are they valuable?


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## lazersteve (Feb 26, 2012)

What color was the metal bar when you started the project?

After shotting/cornflaking what was the color of the metal out of the water?

The salts look like base metal chlorides to me. 

Something is not right or some details are missing.

Here's what porperly inquarted gold looks like after cornflaking:







and after treatment with diluted nitric acid 35%:







Steve


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## shaftsinkerawc (Feb 26, 2012)

For such a low quality gold (placer or hardrock?), how did you determine you had only Au & Ag.
What process was used to recover the Au & Ag before you melted and cornflaked?


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## chawimac (Feb 26, 2012)

Steve:

The bar was white. Looked like a regular silver bar. Once I melted it and made it into shot, you could see the slight yellow hue from the gold.

My flakes look similar to yours, except the color of course. I will take a pic of the flakes tomorrow.

The nitric acid I am using is 69% nitric and not sure what the rest is... Could that be the culprit?

The flakes after nitric, well you saw what they looked like.

I have no idea how the gold was extracted. I am assuming cyanide leaching or mercury. But really I have no idea.

As stated above a have a Fischer XAN120. That's how I know exactly what I am looking at.

Thnx


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## niteliteone (Feb 26, 2012)

chawimac said:


> (snip)
> I have no idea how the gold was extracted. I am assuming cyanide leaching or mercury. But really I have no idea.
> 
> As stated above a have a Fischer XAN120. That's how I know exactly what I am looking at.
> ...



Pure gold (AU) + pure silver (AG) + tech grade nitric. 

That is the combination you are reporting above. Only problem is that this combination will not give the results you are having. :shock: 

Their has to be something else in the mix.
We just need to figure out what it is now.

I have never heard of mother nature producing 8K gold either. :shock: 
Karated gold is a man made mixture of base and precious metals to achieve a desired appearance of gold.

Hopefully this will help find some answers.
Tom C.


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## Geo (Feb 27, 2012)

you will seldom find pure gold in nature. all gold from the ground should be considered in karat gold until it is refined. I've found gold that was several different colors depending on where I found it. some of the purest gold i found was in Georgia, and it was around 18K-20K but never higher according to the assayer. Nevada gold is a close second, as I've never been to Alaska where i hear has the most pure gold from the ground.


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## nickvc (Feb 27, 2012)

As you have a bar that should provide a good result from your xrf so I'd do what Steve suggested and try another sample but alloy it down to 25% Au content, use silver if you have it if not use copper which will take more acid, and the nitric then should be able to do the desired job and remove the vast majority of base metals. The result you posted from your attempted refining shows you haven't removed all the silver so just add that material to the rest and inquart it and you should get the desired result, remember to use diluted nitric it works much better and when you have dissolved your gold in AR add a touch of sulphuric just in case there is some lead in the mix.


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## lazersteve (Feb 27, 2012)

Did you purchase your nitric acid from a mainstream lab supply or a 'mom and pop' company? 

Some solutions of nitric acid may have stabilizers and/or additives. This could be source of your salts.

Maybe there is a software setting in the XRF that is filtering out non-precious metals from the display?

Just to be clear, the photo you posted is of the material after *dilute nitric *treatment, correct?

Steve


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## dtectr (Feb 27, 2012)

Wow! This thread is all over the place! Where to start - 
Cmac maybe you don't want to hear what steve is telling you nicely but but a combo of gold and silver only will not produce blue- green crystals. The silver ion is clear colorless acc to Ammen. There are primarily 3 metals which produce those hues, to my limited knowledge - copper nickel and steel, sometimes. 
The salt crystals are from the concentration of your hour long "boil"-follow good procedure to avoid this in the future. 
You seem to have a vested interest in proving this is what you want it to be, rather than what it probably is. I hope you haven't invested too much in this material. 
Next Geo - to my limited experience niteliteone is spot on- gold karating is performed by humans not nature. It is always an alloy that may read as karat gold but by definition it is not. 
And we are still waiting for the most pertinent info before anyone can help - what is the source of this material? How was it processed into the dore' bar you started with?


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## Geo (Feb 27, 2012)

dtectr said:


> Next Geo - to my limited experience niteliteone is spot on- gold karating is performed by humans not nature. It is always an alloy that may read as karat gold but by definition it is not.
> And we are still waiting for the most pertinent info before anyone can help - what is the source of this material? How was it processed into the dore' bar you started with?



I've found gold nuggets with a red color and others ranging in color from from the reddish color to almost white (silver colored). pure gold is gold colored. what can make gold these colors? not arguing but ive never had an assay of pure gold.


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## dtectr (Feb 27, 2012)

You are correct, just not accurate ;- )
Gold is never pure in nature as it is ALLOYED with other metals, some base some precious. To my limited knowledge, in refining, to speak of "karat" gold is to refer to man-made specific alloys often in the form of jewelry or coinage- semantics, I guess.


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## chawimac (Feb 28, 2012)

Hello all,

Here is a pic of the XRF for what this initially starts out as, as well as the XRF with what is left over. I get 3 things: almost pure gold, almost pure silver, and a 50/50 mix of gold and silver. The XAN120 has two modes, one calibrated which filters out elements and a standards free setting that sniffs out everything! Well, pretty much.

Also is a pic of the Nitric I am using. The pictures in the first post are after Nitric and Distilled water. Half and half if you will. Boiled for a bit.

Question: I would inquart to prevent the silver from encrusting my sample and stopping the AR from working? This still does not explain the salts...

AS far as the starting material, I am not making any claims. I know it sounds weird the mixture, but I get it every week from a guy who has a little mine... Could it be that the seem he is tapping has both gold and silver and it gets mixed up when he leeches it? dtectr sorry but I am not maiking any claim as to anything. I am a noob. Thats why am posting as clearly as I can. I have no idea how it is processed into dore nor where or what it comes from... Yes I have a ton of cash into this, a ton.

Also, incredibly I have seen myself 99.x gold out in the field. I myself thought it was impossible but I have a 350 gram nugget to prove it, hehehe.

Thoughts?


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## chawimac (Feb 28, 2012)

Here are the other pics.


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## chawimac (Feb 28, 2012)

So please enlighten me. What could I possibly be doing wrong? Apart from the 8kt gold and the powerful nitric...


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## lazersteve (Feb 28, 2012)

The gold in the photo appears to have a clear/white crust here and there on it, is that flux ? Pure gold needs no flux when cornflaking.

The color of the treated material does not look like a typical silver chloride crust to me, but it may be the camera. Take a single piece of it and soak it in warm 10% ammonia hydroxide to see if the crust dissolves (silver chloride will) then pour off the liquid and add HCl to the ammonium solution to precipitate the silver as a white chloride again. Add enough HCl to make the solution acidic (below pH 5 would be fine).

Another strange thing is that the treated material looks to have bare spots that have not 'skinned over' possibly due to the gold content, but the color is wrong again, it should be brown, not shiney silver colored in the areas with no crust.

Are you sure the nitric has not been used previously and added back into the jug? Pour some out into a clear beaker and see what color it is. 

The XRF readings do show some base metals, all be it a very small amount.

To fix the problem add three parts silver to the left over material (75% silver/ 25% gold), digest in 35% nitric acid (distilled water only) and dissolve the resulting brown powder/sponge in AR after decanting the liquid from the dilute nitric treatment.

In your opening post the photo of the green material appears very salty to me, what is that a photo of ?

Steve


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## chawimac (Feb 28, 2012)

Steve,

Yes it is flux. I know not to use it now, thnx.

I have to make another batch of the material to test your silver chloride theory. Will post that soon.

As per colors of stuff, well no comment as I know not what to say.

The Nitric is brand new, I have 3 little barrels that I got off the chemical truck. It is clear like water.

I will try a batch at 25% gold and see how it goes.

The first pic is what results when I place the 8k gold/silver metal in 69% nitric/ distilled water, boil and let sit over night.

Thnx for the help and will let you know how it goes.


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## butcher (Feb 28, 2012)

I am wondering if the crust or salts are more white at first and are sitting in light and changing darker, like silver solutions in photography?

keep us posted as you solve this mystery.


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## eeTHr (Feb 28, 2012)

It looks like the XRF printout says 47% Au. That would be about 11 1/4 karat, right?

Apart from being almost twice the desired 6k, would that result in a white dore bar and cornflakes?


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## chawimac (Mar 13, 2012)

Update.

I inquarted the metal once again with some .900 Ag and made sure it was 25% Au on the XRF. I made the popcorn and tossed it in with a potion of half distilled water and half of the Nitric I have.

Curiously all went well. Much more complicated than simple AR but all in all well. Looks like I have some copper or nickel now as the liquid changed color after boiling. The original sample had no color as it was pure gold and silver.

All the popcorn dissolved after adding a bit more nitric. I then proceeded to the AR process.

It was horrible to filter this! Much more difficult. The gold just did not want to settle down! Any tips???

The problem, it turns out was the language barrier, as I failed to read the water bottle correctly. The water used in the first test was an electrolyte solution!!! Hence the salts. Once that ran out the problems stopped. Go figure.


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## eeTHr (Mar 13, 2012)

chawimac said:


> It was horrible to filter this! Much more difficult. The gold just did not want to settle down! Any tips???




Are you referring to the gold remaining in the nitric, or to the gold powder precipitated from the AR solution?


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## butcher (Mar 13, 2012)

Sounds like tin, in solution making filtering a problem.


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## eeTHr (Mar 14, 2012)

butcher said:


> Sounds like tin, in solution making filtering a problem.




I took it to mean that his gold wouldn't settle to the bottom.


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## Harold_V (Mar 14, 2012)

Heh! From my understanding, the solution wasn't separated from the honeycombed gold, but was, instead, allowed to remain while the gold was dissolved. Sounds to me like there's a lot of silver chloride present, with dissovled gold well mixed within. 

Please tell me I'm wrong. 

Harold


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## eeTHr (Mar 15, 2012)

chawimac---



eeTHr said:


> All the popcorn dissolved after adding a bit more nitric. I then proceeded to the AR process.



Strictly speaking, the above sequence doesn't make any sense, either.

Overall, a very confusing post.

I would recommend that when posting, you slow down and explain everything in exact sequence, and don't leave out any steps by *assuming* that people understand that they were done. If you want help in catching any possible errors---how is anyone supposed to know what's a possible error, and what you're just assuming that we somehow *know* that you actually did?

It might be difficult to get help from people that you have just confused. 8)


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## chawimac (Mar 16, 2012)

Hehe, here I'll slow down a bit. Sorry.

It helps if you read the whole thread as there were a lot of issues involved.

Where I am having problems, or rather inconveniences is in filtering gold that I dropped with SMB at the end of the AR process. I had a pretty good handle on the AR process of refining, where I am expecting a clay colored gold mud/sludge. In the in-quart process, when it comes time to drop the gold with SMB, the reaction is different as the gold is different. The color is much darker and it is not a slime/sludge. It is rather a very fine powder that does not want to gravitate to the bottom of the container. I know I am getting most of the gold I am supposed to because the numbers add up, but the filtering process is much more difficult that a basic AR process that does not involve previous Nitric/In-quart process.

As far as tin being present, perhaps but none was indicated in my XRF analysis. Maybe a trace amount. I have read people complain about this (filtering) in the forum before, but first hand experience really puts it in perspective.

Harold, I am confused with what you propose. I inquarted, made popcorn, processed the material with nitric/water, the result was mostly dissolved gold. I drained the silver containing solution and dropped a bunch of silver with some PC copper from that solution. Kept adding copper until it would no longer dissolve. Got out the right amount of silver I was expecting. 

The brown material that was left in the reactor was washed with distilled water a couple of times. (Yes I dumped that water with the silver as I know it contains silver.) What I said before was that the original popcorn did not fully dissolve with the 50/50 Nitric solution. I had to add a few drops of nitric here and there until all the popcorn dissolved. I used my technical grade Nitric with distilled water I bought in my chemical supply place, on a 50/50 ratio as described throughout the forum.

The material in the reactor was then processed with AR as I would normally do with material containing 12% Ag or less, as I am assuming this material qualifies. So what I did was process the material with AR in several additions, boiled a bit at the end of the reaction. Once reaction was done, I added Urea dissolved in water until my solution stopped fizzing. I added Ice, filtered this solution to remove any silver traces. I added SMB dissolved in water to drop the gold. Filtered, for about a day. haha The last part was the issue.

Am I being concise enough or is there anything anyone would want me to elaborate? Pretty standard process I think... Or am I wrong? As I stated before the salts in the first post came from the water I was using.

Comments?


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## lazersteve (Mar 16, 2012)

After filtering out the ice solution the liquid is where the gold should be (a simple stannous test to confirm). 

You then add SMB and let the gold settle over night. Test the solution again for dissolved gold, if present add more SMB and repeat the settling process.

After the gold sponge has fully settled carefully siphon or decant off the barren liquid leaving the gold in the flask in which it was precipitated.

The next few steps are a variation of Harold's wash process for gold sponge:

Now rinse once or twice with water, letting all the powder settle between decanting and the second wash.

Now cover the gold powder with HCl and place a watch glass over the beaker top. Heat to a gentle boil on continue heating until the HCl no longer darkens.

Let cool, settle, and siphon off the acid testing for Au before properly disposing of the barren liquid. 

I prefer a few final water rinses to flush out the last of the barren solution from the gold sponge.

If I suspect silver is still present (dark colored gold sponge) I also do a wash with warm ammonium hydroxide 10% and follow up with a few more water rinse/settle/decant cycles. Always swing the pH of ammonia solutions below 7 with HCl before properly disposing/storing to prevent exposive comppounds from forming if the liquid drys out.

At this point I begin drying the gold in the same flask it was precipitated in. 

Once the gold no longer sticks to the flask when it is swirlled you are ready for either a second refining or melting. Melt a small sample and check for discoloration in the flux and/or on the surface of the button. If the button turns out shiny melt all of the gold sponge in a properly prepared dish. If the gold button looks discolored or crusty redissolve all of the powder and the button again in AR repeating the entire process for the highest purity gold.

Steve


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## eeTHr (Mar 16, 2012)

chawimac---

If you want to know exactly how to solve your problems, then you should use exact terminology when describing what you have done. When something "dissolves," it goes into solution. Nitric doesn't dissolve gold. This can make people wonder what you actually did.

Avoid the use of urea, if possible. Instead, if you suspect left over nitric in your AR, after all your gold is dissolved, weigh a small bead of gold, and put it in the (heated) AR. If it dissolves, do another bead, and so on. When a bead won't dissolve any more, dilute the solution, chill if you want to, and filter the solution into another container (pick what's left of the bead out of the filter). Then precipitate.

When you are dissolving gold from inquartation, you can estimate the amount of SMB required pretty accurately, and use just a little bit more. Test the solution with stannous after the drop, to be sure none remains in solution.

If you don't want to wait for all the gold to settle, after the majority of it is on the bottom, siphon off the solution into another container and let it settle for a week. And process the gold that has already dropped. There shouldn't be very much gold in suspension, as it must be very tiny particles to suspend. The dirtier the AR, the more dark, tiny particles there will be.

When you rinse the dropped gold, bring it to a boil until until the rinse solution doesn't gain color. This boiling will also *agglomorate the gold powder* better, and you shouldn't have any problems with powders suspended in the rinse solutions, thereafter.


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## chawimac (Mar 18, 2012)

eeThr

Thnx for the advice. Will try to be more clear.

Steve, great advice. I do appreciate.

To followup on the comments:
Why avoid urea? Some people suggest it. As far as a button here or there, it doesn't seem very practical. I am no refiner but I do 2 kilo lots in my little reactor. Some of this stuff may seem simple when doing 50 grams, but at a larger scale its very laborious. I know refiners are set up to process this easier, but I am stuck in the middle. Also, is ice optional? Is water to dilute enough to drop out the silver? I just feel I am not getting all the silver sometimes.

I XRF everything before I process, that way I know how much gold or silver to expect and how much chemicals to use throughout the whole process. I do not use SnCl, as I get all kind of weird colors. Haven't quite gotten the handle of it yet. I use a Hanna Redox meter. Pretty cut and dry. My SnCl gets greenish after a week or so.

Back to filtering the gold, it isn't practical to wait a week for this stuff to settle. Hehe I am poor, and I can loose my shirt speculating so long on gold! Process gold and wait a day to settle, then wash a couple of times, waiting for it to settle every time. Doesn't that take forever? There must be an easier way??? I will try the boiling of the gold to get it to agglomerate. Hope that speeds things up. I do appreciate the interest and help of all.

Thnx


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## lazersteve (Mar 18, 2012)

Heating the gold after adding SMB will speed the settling process, boiling will not as the motion of the boiling liquid will keep things stirred up to a slight degree.

Settling for a full 24 hours can be avoided at the expense of some of the yields. You can allow the bulk of the gold to settle for 30 minutes to one hour, then pour off the suspension of fine gold particles that remains along with the gold that may still be reducing in the solution. The liquid that is poured off will contain a small percentage of the gold if you precipitate from pure solutions without base metal contamination. The more contamination in the liquid, the slower the gold settles and the more you will pour off with the solution when 'speed refining'.

Filtering with a buchner funnel and vaccum flask will eliminate the need for settling, but you will temporarily lose some gold to the filter paper. The paper can be burnt later to recover the 'lost' gold. Occassionally some of the finer particles of gold make it past the filter paper and you will need to filter more than once. A buchner setup is not in some peoples budget and has the added cost of electricity, filter papers, and labor. All to often you will find the vacuum process slows to a crawl and you'll be right back to waiting. There are some ways to speed the process, but you must weigh the cost in time and equipment verse the change in the price of gold.

If you are not in a race against time to turn the gold into money, patience can sometimes pay off with slightly higher yields and less equipment and labor costs.

Steve


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## eeTHr (Mar 19, 2012)

chawimac said:


> eeThr
> 
> Thnx for the advice. Will try to be more clear.
> 
> ...




Chawimac---

If you are doing large quantities in one batch, you should read this post by Harold_V. It addresses a few things which would be important to you, including a couple which you asked about.


P.S. People avoid using urea because of the reasoning that it's just an additional substance in solution, which might cause problems later, and it is unnecessary. For large quantities of Au in solution, use a larger button of Au. Just weight it before putting it in, and again after removing it, and you will know how much was dissolved into your solution, for subtraction of that much powder later if tracking the yeild is important. And it totally eliminates guesswork about the nitric content, eliminating unforseen extra steps. It's just a neater, more certain way of doing things, when you are concerned about time.


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