Need to recover a significant amount of gold from 25l of neutralised Aqua Regia Solution

[goldkron]

I failed to seperate the base metals from the Gold foils and pins, etc. So essentially I have 25l of the neutralised solution with a lot of gold dissolved along with the base metals. The only success I had in recovering any was by using a mercury based method. Is there another way to force the gold out while leaving all the base metals dissolved? Should I be adding copper powder to the solution?


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[17freeliberty76]

what was your initial processes, known base metals, amount, etc.... that would help alot :!: :?:

 

[jarlowski1]

The addition of Sodium metabisulphite (Smb) (1.5 times the estimated amount of gold) will drop the gold out of a denoxed AR solution. To denox the solution you should add sulfamic acid until no reaction occurs. Cool the solution with a ice to make sure all the silver is pushed out of the solution. Then add the smb. Allow it to settle overnight. The result will give you a dirty gold powder which should be washed and refined again.

 

[goldenchild]

Copper. If your solution is 100% aqueous then use copper to drop out the PMs. Then filter out all the PM powder and process separately. Being neutralized I think you'll have to acidify it for the PMs to plate onto the Cu.

 

[Barstool miner]

the ancient Greeks used to suspend Copper wire in the neutral Pregnant Solution
and the Gold Reduced on to the Copper and drops off as Gold tear drops .Some form of Galvanic action . I use an Activated Carbon column to collect Gold out of full strength AR.

 

[anachronism]

the ancient Greeks used to suspend Copper wire in the neutral Pregnant Solution
and the Gold Reduced on to the Copper and drops off as Gold tear drops .Some form of Galvanic action . I use an Activated Carbon column to collect Gold out of full strength AR.

That's out of a pure solution I assume ?

 

[g_axelsson]

The addition of Sodium metabisulphite (Smb) (1.5 times the estimated amount of gold) will drop the gold out of a denoxed AR solution. To denox the solution you should add sulfamic acid until no reaction occurs. Cool the solution with a ice to make sure all the silver is pushed out of the solution. Then add the smb. Allow it to settle overnight. The result will give you a dirty gold powder which should be washed and refined again.

Assuming (quite a big assumption in this case) that "neutralized AR solution" actually means chemically neutralized solution at pH 7...

He was talking about a neutralized solution so there is no acids there but there might be nitrates. I don't know how well sulfamic acid works in a neutral solution, but at least smb doesn't work unless there are some acid there.

I would suggest to use the easiest method and start over again. Add copper scrap and a bit of hydrochloric acid to get it acidic pH. If there are brown gas coming off then there are residual nitrates in solution and the nitric acid is dissolving copper. When it stops, add a bit more hydrochloric acid again. Repeat until adding HCl doesn't produce any NOx gases. Now the gold can cement on the copper without being redissolved. When the liquid tests barren with stannous chloride you can go on with the next step and separate the solids from the liquid. The sediments can then be refined again to get rid of any copper.

Göran

 

[g_axelsson]

I failed to seperate the base metals from the Gold foils and pins, etc. So essentially I have 25l of the neutralised solution with a lot of gold dissolved along with the base metals. The only success I had in recovering any was by using a mercury based method. Is there another way to force the gold out while leaving all the base metals dissolved? Should I be adding copper powder to the solution?

More details please or we might guide you in the wrong direction.
- How much scrap? Quality?
- How much is "a lot of gold"?
! Do Not Use Mercury ! Especially if you are using acids. It will produce water soluble mercury salts and that can easily poison both you and anyone around you. There are no reason to use mercury in modern gold refining.
- Neutralized? Do you mean pH 7?
- Have you tested with stannous chloride? If not, stop whatever you are doing and read up on testing. Maybe your gold isn't there but hiding in the solid waste. Stannous is the eyes of the refiner, it's easy, quick and sensitive.
- Have you read Hoke yet?

Answer these questions from me and other members so we can help you i the right direction.

Göran

 

[jarlowski1]

Goran is right. I assumed he meant denoxed. I thought it was a language barrier that made him say "neutralized" instead of denoxed. So more information would be needed.

 

[Geo]

You are giving an amount or volume of solution. How much weight of each type of item did you dissolve in 25L of solution. Fully gold plated pins vary wildly in both directions from norm, if you can find what the norm is. The question shouldn't be how much is there, but rather, how can I ensure that I have recovered all there was to get. After you have determined the weight of metal, do some research and figure out how much aqua regia was needed to dissolve that amount of metal. Was there any solids left after the dissolution? If so, was it black solids or white solids? It does matter. Did you test the solution with stannous chloride? What did the positive test look like? Since there is so much base metal involved, you may use ferrous sulfate to precipitate gold from a "dirty" solution of mixed metals selectively. More so than with sodium metabisulfite. It takes a little longer to settle but the drop is much cleaner assuming you have destroyed all free nitric acid. You can test the solution, immediately after precipitating with ferrous sulfate, with stannous chloride. Something you can't do with SMB because you will get a false positive. A positive test after adding ferrous sulfate is a true positive and means you need to add more. You will know you have precipitated all of the gold after two negative test done an hour apart.

 

[Geo]

the ancient Greeks used to suspend Copper wire in the neutral Pregnant Solution
and the Gold Reduced on to the Copper and drops off as Gold tear drops .Some form of Galvanic action . I use an Activated Carbon column to collect Gold out of full strength AR.

That is cementation. Ionic exchange. The reactivity series of metals tells us that metals that are more reactive than the metal that is in solution will exchange ions with what's in solution. Copper is more reactive than gold or silver or any of the other noble metals. That means copper will go into solution and the other metals will come out of solution as a metal. Metals that are more reactive than copper will remove the copper from solution in the same way. Iron is more reactive than copper so iron metal will cement copper from solution. This is also steps used in treating waste solution before disposal.

 

[goldkron]

what was your initial processes, known base metals, amount, etc.... that would help alot :!: :?:

My methods improved throughout my overall process but primarily I performed as follows:

I processed some commercial boards used in cell towers, I managed to find around 14 at my local dump a few months back.

Initially I was dissolving everything in pure nitric acid not taking note I should have seperated the different metals. This is did start doing about 4 boards in. And later started dissolving in aqua regia. I then used some urea to attempt to neutralise the acid which did the job but also made a big mess in the solution. Once filtering all the excess urea out, I then started adding sodium metabisulphate and presumably added too much. The whiteish sand at the bottom of the beakers, I extracted and dried out in my oven which formed a dust, except there little to no gold in the dust. Unfortunately I had to move house which is when I poured all the various solutions into 1 x 25l drum and it's sat for about 2 months. I did add a lot of water to the solution to ensure it was neutralised.


The metals I have found so far include mainly zinc, copper , aluminium, rhodium, silver and very little gold. My solution has always tested positive for gold when using stannous chloride but the gold remains dissolved. I am now ready to start trying to extract it again, I need some solid advice and to not make any more timely mistakes.

Thanks

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[goldkron]

The addition of Sodium metabisulphite (Smb) (1.5 times the estimated amount of gold) will drop the gold out of a denoxed AR solution. To denox the solution you should add sulfamic acid until no reaction occurs. Cool the solution with a ice to make sure all the silver is pushed out of the solution. Then add the smb. Allow it to settle overnight. The result will give you a dirty gold powder which should be washed and refined again.

I def messed this process up previously which may explain why my SMB precipitated no gold. Thank you

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[goldkron]

I failed to seperate the base metals from the Gold foils and pins, etc. So essentially I have 25l of the neutralised solution with a lot of gold dissolved along with the base metals. The only success I had in recovering any was by using a mercury based method. Is there another way to force the gold out while leaving all the base metals dissolved? Should I be adding copper powder to the solution?

More details please or we might guide you in the wrong direction.
- How much scrap? Quality?
- How much is "a lot of gold"?
! Do Not Use Mercury ! Especially if you are using acids. It will produce water soluble mercury salts and that can easily poison both you and anyone around you. There are no reason to use mercury in modern gold refining.
- Neutralized? Do you mean pH 7?
- Have you tested with stannous chloride? If not, stop whatever you are doing and read up on testing. Maybe your gold isn't there but hiding in the solid waste. Stannous is the eyes of the refiner, it's easy, quick and sensitive.
- Have you read Hoke yet?

Answer these questions from me and other members so we can help you i the right direction.

Göran

Hi, yes I have tested with stannous chloride and it shows positive. When I say neautralised I just mean that it is not reacting as an acid anymore and I have not tested the PH, although I know wish I had done.

Scrap is hard to estimate with regards to gold but conservatively 50-75gms .

Quality was good.

Don't want to use mercury, far too dangerous and I believe not necessary, the only reason I am tempted is that the one time I did use it, I managed to pull 40g of dust which was 20% gold equalling 8gms. That was processing around 2 litres of my solution. Thanks

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[anachronism]

Can I just clarify that you're expecting to get 50-75g from 14 boards?

If I have misunderstood you then please accept my apologies however if I didn't misunderstand you where did you get the data that suggested this yield?

Jon

 

[goldkron]

Can I just clarify that you're expecting to get 50-75g from 14 boards?

If I have misunderstood you then please accept my apologies however if I didn't misunderstand you where did you get the data that suggested this yield?

Jon

Hi Jon, sorry but neglected to mention that there was also quite a lot of gold plated jewellery. I have no data to confirm how much gold there is except an estimate and "guesstimating [emoji38]" from the only data I have, I did pull out 8 grams from 2litres and I have another 25 litres to process. I must emphasize these boards were a good few kilos each and were covered in gold foil, pins, etc. My best guess is that might have been old damaged boards from a 3g tower.

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[17freeliberty76]

what was your initial processes, known base metals, amount, etc.... that would help alot :!: :?:

My methods improved throughout my overall process but primarily I performed as follows:

I processed some commercial boards used in cell towers, I managed to find around 14 at my local dump a few months back.

Initially I was dissolving everything in pure nitric acid not taking note I should have seperated the different metals. This is did start doing about 4 boards in. And later started dissolving in aqua regia. I then used some urea to attempt to neutralise the acid which did the job but also made a big mess in the solution. Once filtering all the excess urea out, I then started adding sodium metabisulphate and presumably added too much. The whiteish sand at the bottom of the beakers, I extracted and dried out in my oven which formed a dust, except there little to no gold in the dust. Unfortunately I had to move house which is when I poured all the various solutions into 1 x 25l drum and it's sat for about 2 months. I did add a lot of water to the solution to ensure it was neutralised.

:|after reading what i wrote hereunder... not all of this pertains to you.. AFTER YOU READ THIS "IF THE SHOE FITS" Im not being a prick or a smartass when I say this, so please dont take this the wrong way... if you do i apologize in advance.
:?: so out of 14 boards that you tried to process ..... with everything still on it, you used 25 Liters HNO3 HCL H20?
:idea:
Go grab the lid, put it back on the drum, take that drum and store it somewhere safe. THEN FORGET EVERYTHING YOU THINK YOU THOUGHT YOU KNEW... get a copy of HOKE'S book, read it, then read it again and take notes. Or if in PDF use the highliter and add comments/notes as you read. After that sift thru the forum and study, dont ask questions, if you have one write them down.... after you accumulate 50+ questions, answer the ? yourself first. Then "open-book test" those 50+ Q&A's you previously took..

*****DONT START PROCESSING UNTIL YOU GET 98% RIGHT*****

Then ask questions on the forum....almost every thread that I have read on here and ive been digging since I joined and well before that as a guest. People post questions then 9/10 times the "big guys" answer, sometimes debate, they even teach eachother new things... its clearley posted in the threads and you will find great information & hopefully comprehend and learn from the best in the industry.

The question.... that was just answered, with all the right information.....
IN THE EXACT SAME THREAD, RIGHT UNDER THE REPLIES/POSTS.... THAT THE "NEW MEMBER" JUST SCROLLED PAST.... WITHOUT READING ANY OF THE INFORMATION... OR THEY DID READ AND CANT COMPREHEND/ RETAIN/WRAP THERE HEAD AROUND..... DOESNT UNDERSTAND WHAT A FORUM IS .. :?
I DONT HAVE THAT ANSWER TO WHY PEOPLE DO THIS.... BUT IT DRIVES ME UP A WALL... Let me tell you why... I'AM IN THE MY GROOVE... STUDYING.... LEARNING.... PUMPED UP THINKING BOUT MY END GOAL :G :G :G THEN HERE COMES "THROW YOU OFF OF YOUR GROOVE QUESTION"......ME LOOKING AT MY SCREEN :arrow: :shock: :?

The forum is full of this unneeded B/S.... IF YOU CANT TAKE THE TIME TO LEARN THIS STUFF YOU SHOULDN'T BE DOING IT... ESPECIALLY THE FUNDAMENTALS OF THIS HOBBY OR INDUSTRY.... THE "BIG GUYS" KEEP POSTING THE SAME BASIC FUNDAMENTAL THINGS OVER AND OVER AGAIN... I PRAISE THEM FOR THEIR PATIENCE, AND PASSION TO HELP PEOPLE.. :G I KNOW I WENT ON A BIT OF A RANT... BUT ITS FRUSTRATING TO SEE SOME OF THE POSTS.... IM TRYING TO MAKE A LIVING FROM THIS AND IVE PUT ALOT OF TIME STUDYING IM JUST HAVING A HARD TIME FINDING MATERIAL AT A REASONABLE PRICE, OR CONTRACTS.... MOST OF THESE PEOPLE THAT POST THESES SAID POSTS PROB WASTED IT OR THREW IT IN THE TRASH.... GOLD FEVER KICKED IN.... THEN FADED AWAY ONCE THEY FOOUND OUT YOU ACTUALLY HAVE TO STUDY AND LEARN AND SPEND HOURS AND HOURS AT IT. IM DONE...... THANK YOU FOR YOUR TIME

 

[goldkron]

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[kurtak]

yes I have tested with stannous chloride and it shows positive.

Are you sure the test is in fact positive for gold ?

If you used to much SMB when you tried to precipitate the gold you could very well be getting what is known as a FALSE positive

Use a Q-tip --- wet the end of it with your stannous chloride - then put a drop of your solution on it - take a picture of it - post the pic here so we can see it

IMO - based on everything I have read here - until I/we SEE your stannous test - it is a waste of time to try & solve this problem

IF (big if) in fact the stannous test is positive for gold - we will also need to know the Ph of the solution --- so get some Ph paper & show us a picture of the Ph test results

Until we SEE those test results this will continue to be nothing more the ????? with the answers nothing more then assumptions (assumption there is even gold in solution)

Kurt

 

[anachronism]

As Kurt said- PICTURES please 8) 8) 8)

Let's see that Stannous test.