Salt in Acid

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.

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

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?

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

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?

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

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.

Thnx

Click to expand...

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.

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.

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.

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

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?

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?

Click to expand...

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.

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.

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?

Here are the other pics.

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

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

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.

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.

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?