# Gold recovery .. Aqua regia Ash + papers



## RichWat123 (May 23, 2017)

Morning, 

I have looked and searched (as members will tell me to do) and cannot pinpoint an exact answer.. so to the forum.

I don't wish to make anyone's life hard, but if someone just knows the answers I would appreciate it.

Q. If I have ash and/or filter papers (mulch) that I know has aqua-regia with gold dissolved .. best way to recover as much liquid gold? 

I have been suspending in sieve and leaching but im not convinced ..

Q. If I incinerate this mulch .. to lessen the amount.. back to ash as it were.. what happens to the gold that is dissolved? 

I understand if I had precipitated to powder and had all my filter papers.. I am curious as to papers and mulch containing agua-regia gold solution.

Thanks in advance.


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## butcher (May 23, 2017)

I may not understand your question.
If you have papers with a gold chloride solution, you do not want to dry and incinerate. The gold is soluble in water and the solution can be washed from the paper. Gold and chloride (salts) are volatile, so you can lose some gold at the higher temperatures.

If the papers contain carbon and paper and gold chloride salts or solution, remember the carbon can absorb some of the gold, in this case wash out as much of the gold solution or salts as possible, the paper and carbon can then be washed with a solution of sodium hydroxide and rinsed squeezing out the liquid dissolved salts from filter before drying, these papers and carbon ash can be incinerated later where you may need a carbon source in a recovery project...


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## RichWat123 (May 23, 2017)

Thanks for the reply.


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## goldsilverpro (May 23, 2017)

If you want to use AR, you must first attempt to get total incineration of the burnables, with no black carbon visible.


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## artart47 (May 24, 2017)

Hi Rich!
About a year and a half ago, a member sent me a pretty good amount of powder that was from boards that he had processed. He had leached the materials and dropped out and dried everything that had dissolved in the solution. I'm sure that there had been a good amount of gold in the original powder.
I began working on material, small amounts in test tubes and wasn't finding any gold content at all. Upon inquiring about how he processed the material, I learned that the final thing he did to kill the acid/salts in the powder was to roast it to red heat. He told me that it make a large amount of smoke. There was one problem. If the gold had been in a metallic state, the smoke and fumes would have been chloride salts breaking down and/or other debris volatilizing, but he didn't fully understand what he was trying to do. His gold was in the form of gold chloride and in the smoke was all of his gold. a very costly mistake!
Please! Study until you fully understand what you are hoping to accomplish with any process, the chemistry behind it and the safety necessary before beginning.
Good luck!
Art.


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## RichWat123 (May 24, 2017)

Hi,

Thanks again for the replies.


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## g_axelsson (May 24, 2017)

Gold chloride being volatile is a tricky subject and I think it might be a matter of slowly increasing the temperature to avoid losses.

There are a lot of evidences for losses of gold when gold is heated with chloride containing materials. But on the other hand as long as there is base metals or silver present that is preferably removed when chlorine is bubbled through molten gold (Miller process).

Gold(III) chloride decomposes into gold(I) chloride and Cl2 at 250 C.
Gold(I) chloride decomposes into metallic gold and chlorine at 300 C.
According to wikipedia https://en.wikipedia.org/wiki/Gold_chloride

I think Dean made some experiments with carbon loaded with gold chloride but I don't recall the exact results right now.

Incineration of gold chloride containing material could lead to losses but it is also possible to do. I have done a direct incineration of some gold chloride containing rags after spilling some gold chloride. Since I didn't know how much I had at start and what amount of solution I missed I have no real knowledge of what the losses during incineration was, all I can say is that I tried to increase the temperature slowly and the amount of gold recovered seemed to be about what I was expecting.

Göran


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## kamal Ghobadi (Jun 13, 2019)

Dear SIr or Madam
I am trying to recover gold from ore by aqua regia.first I crushed the ore and poured the ore powder to a plastic container 2.added HCL until to cover the powder 3.let it to react with ore 4.add HNO3 again and wait for 2 days to finish the reaction 5.filter it and use some NaOH for remove HNO3 6.add SMB and change the colour to black 7.wait for precipitation of gold 8.black wasted material precipiated in bottom and I do not know what I have to do at this step?
if it possible PLZ help me with more info


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## FrugalRefiner (Jun 13, 2019)

What does an assay of your ore say? Adding acids to an unknown ore is very dangerous business.

In general, trying to process ore with AR is not a good approach.

Dave


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## lanfear (Jun 28, 2019)

I would like to continue on the original topic..

When you guys have filtered your auric chloride, and washed out the filter. What do you do with the filter?
Putting it in the regular filter pile is no good..
(I am doing this atm)
Maybe dribble some smb on it and then sticking it in the filter pile?
I know it should be next to nothing of gold left there, but still...?


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## nickton (Oct 11, 2019)

I am not one of the experts here but I think what we should do is rinse out those filters with water as best we can, though this will obviously give a minute amount of very diluted of auric chloride and seems hardly worth the effort. Perhaps I will keep the more yellow used filters in a separate container and process them all at once in sodium hydroxide (like butcher said), instead of throwing them in with other ones. I didn't realize that carbon absorbed gold either.

I wonder if there is a way to remove gold absorbed in carbon.


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## g_axelsson (Oct 11, 2019)

nickton said:


> I wonder if there is a way to remove gold absorbed in carbon.


Incineration.

In the end, you have to ask yourself how much work you are ready to put in to get the last part of gold. I throw all my filters into the same pile, anything I suspect could contain values. Then I'll just process it as a single batch. Sure, I'll have some losses but I have other material that I rather work with than spending hours on many smaller lots of old filters with trace amounts.

I might treat it with lye though, converting any chlorides to oxides and hydroxides will make it nicer to incinerate and converting silver chloride too.

Göran


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## Martijn (Oct 11, 2019)

I rinse my gold filters (coffee filter in a funnel, right after filtering the solution) with a spray bottle with warm water. Then test with a drop of stannous chloride while its still wet to see if there is anything left. Never had a significant color change. If you rinse well its not worth recovering i think.


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## nickton (Oct 16, 2019)

The only problem I have with rinsing is the extra dilution it creates, even though that can be corrected with the tedious process of evaporation. I'm at the point now where I try to avoid evaporating. If your auric chloride solution has too much water the precipitated gold becomes too fine a powder, doesn't get caught in a filter, and becomes generally another pain in the you know what to deal with. 8)


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