# Gold refining with AR



## Riyoso (Oct 10, 2008)

I dissolve gold CPU scrap with AR and precipitate with SMB, I seem to never get the same results: All the gold does not seem to precipitate or sometimes no gold precipitates, even though I follow the exact same procedures every time. Is there a specific way of adding SMB to AR, or any other method of precipitating with SMB that I am not aware of? I do deNOX with urea before any precipitation.
Kind reagrds
Riyoso Abrahams
Namibia


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## butcher (Oct 11, 2008)

Aqua Regia its very important to rid nitric, also rid base metals prior to using if posible too much base metals a problem, I heat it evaporating solution down to a syrup(but not overheating), (not to crystalize), add a little HCl to wet, repeat this three times total, last time few drops of sulfuric acid if lead in solution, here I usually add a few prills of urea to see if it will fizz ( or as HAROLD suggest a little pure gold) add at least 3 times amount of water (some use more), if silver or lead in solution will usually fall as white powders, can add a little table salt to see if any silver left in solution, settle, decant, filter silver and lead (can seperate the lead and silver with boilng PbCl more soluble Hot than AgCl).
The solution containing Gold (and if metals while disolving were brought up to 150 deg for a period of time in the aqua regia) PGM's, can be dropped from the solution with many different methods, some precipitants are SO2 gas, which is kind of what you created in solution with SMB sodium meta bisulfite, sodium sulfite ect,. 
Or with copperas (ferrous sulfate), I make mine from transformer Iron laminates cut small pieces dissolved in dilute sulfuric acid with heat adding little sulfuric to keep acidic if storeing for latter use,(can evaporate to crystal) or can precipitate with a Metal lower in electromotive series than metal you trying to precipitate from solution, there are many precipatants that will work, 

{if all else fails you can use Zink dropping all metals below it copper gold pgm ect and incenerate off prior acid and start over, not loosing your valubles}. I find if I have a heavy copper solution in with my gold in aqua regia it is difficult, and I use copper to drop gold with a little copper ( decanting and reprocessing it lowers copper content making purer and easier next run through), also a warm water solution with precipitant in it helps me (I dont wory about extra water most of chloride metals left are soluble), letting sit at least 24 hours siphoning off liquid from brown Gold chloride powder, 
I dont discard my old spent solution as it still will disolve metals with Oxidizer added and lil fresh HCl, and may contain trace of gold, i use it on lower grades of scrap. or to clean up a copper gold powder from another batch ect, having a stock pot of it boiled lil bit thick with copper chain in bottom for storage non sealed container of it(nice brown powder in bottom). Aqua regia is to me harder to deal with than alot of these other methods and in my opinion used mainly for final stages or harder to disolve scrap, the more you get rid of base metals prior to using Aqua Regia the more successful it will and you be, and the cleaner the final product. there is usually safer processes,but Aqua Regia is a great tool, I try not to use a sledge hammer when I need a tack hammer am usually more successful. 

Hope this is helpful as I am by no means an expert on the Aqua regia process, & have my troubles too, and would like to see a topic devoted just to it, with the more expierienced of our group describing the technique and problems, as this seems to be an Old art of the trade.


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## nickvc (Sep 21, 2009)

one of the best precipitants i ever used /use is ascorbic acid this i add after killing the nitric with urea. When i was refining commercially i used ferrous sulphate first as its much cheaper and then used ascorbic to make sure all the gold was precipitated out.


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## eeTHr (Sep 21, 2009)

nickvc;

How selective is ascorbic acid?


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## nickvc (Sep 28, 2009)

sorry im not a chemist but im sure someone on here can give you an answer to how selective ascorbic is. When i was refining commercially i produced gold of 999 fairly consistently when required but most of my gold went back into the jewellery trade as carated products so small inclusions of copper and silver really didnt matter as they are part of the alloy been made. Speed of turnround was usually more important than producing 999 or better gold. If you have a clean gold solution which you can get by following harold or any other of the clever people on here im sure you would drop gold of 999 easily. i never could sell gold onto the market as, like most of us if not all of on here, i didnt have good delivery status. This was a commercial venture and i must say it was pointless to refine to a high grade if it didnt pay, this i think remains true today,if you do it for fun or to prove you can fine, but in a commercial sense check out wether it is worth the effort. As i did say ascorbic isnt cheap i used ferrous sulphate first and ascorbic to finish the precipitation. Not sure if what i did was right but it made money so i guess i did something right.


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## eeTHr (Sep 28, 2009)

nickvc;

Yep, it pays to supply what is in demand.


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## asllan (Apr 6, 2010)

i won to now how the method of gold refining ar simply please help


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## nickvc (Apr 6, 2010)

asllan said:


> i won to now how the method of gold refining ar simply please help


There are loads of posts on the forum which cover refining by most methods,my advice to you is to read Hoke ,available on here as a free download,and use the search function and read about the methods that suit your purpose.There is no easy way to start you on the refining of gold unless you understand the basics so research and read and ask questions when you are better informed and will understand the answers you receive.Good luck and dont give up, refining is not something to be rushed and a good understanding of the dangers and problems will save you and us much time.


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## chemist (Apr 6, 2010)

Is there any smell associated with precipitation using ascorbic acid?
SMB smells bad (due to the excess SO2). If Ascorbic has no bad smell or dangerous fumes, it may be preferable for some people.


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## goldsilverpro (Apr 6, 2010)

asllan said:


> i won to now how the method of gold refining ar simply please help



Welcome to the forum.

Here is the free download for the Hoke book. It is simply written and covers the AR process in great detail.
http://goldrefiningforum.com/phpBB3/download/file.php?id=2480

I doubt if anyone is too keen on taking you step-by-step through the process. It's not that we don't want to help you. It's just that it can be quite long and it has been already covered about 100 times, in detail, on the forum. 

I would suggest first spending a week or two reading the book and searching the forum. Once you have some background on the process, we will be glad to answer any specific questions. 

If you have trouble searching, use the search engine on Steve's site, http://goldrecovery.us/ It works better than the one on the forum. You'll also find quite a few very instructive videos there on several different refining processes.


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## nickvc (Apr 7, 2010)

chemist said:


> Is there any smell associated with precipitation using ascorbic acid?
> SMB smells bad (due to the excess SO2). If Ascorbic has no bad smell or dangerous fumes, it may be preferable for some people.


If all the nitric is gone the only smell i can remember was a slight acidic one if the nitric is still their it will fume nitrous clouds so care is to be recommended,be aware ascorbic is far from cheap and i only used it usually after ferrous sulphate as it seemed to speed up the dropping time and time was the main problem i had as my customers wanted fast turn round of their material.


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## chemist (Apr 7, 2010)

Nickvc---Thanks. I didn't notice the price, but I do remember seeing bags of ascorbic acid the other day at a store that sells supplies for making beer and wine. I don't know what they use it for. Perhaps they make beer with added Vitamin C!
Considering the foul smell and dangerous aspects of SO2, I would think that a minor cost increase (over SMB) might be acceptable, especially for folks that do small batches. 
It would certainly be safer to move and store ascorbic acid.


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## gengates (Apr 19, 2010)

nickvc said:


> chemist said:
> 
> 
> > Is there any smell associated with precipitation using ascorbic acid?
> ...



newbie in the house here....
just learning how to refine gold, and am not a chemist. 

nickvc and anybody, i tried using ferrous sulphate in dropping gold, all i get is the very few fine white colored dust, that i believe, the powder ferrous sulphate i mixed with my gold chloride..... and its not dropping any gold i extracted from 3 cpus and few pins. i used 1:4.5 nitric and muriatic acid, neutralize the solution with urea, then used ferrous sulphate with out success of dropping. Pleas help. I used the ferrous sulphate that you buy in a drugstore, in capsule form, just extracted this white powder and i just drop it straight to my gold chloride....is this ok? or any ferrous chloride you can suggest.

thanks


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## Harold_V (Apr 20, 2010)

gengates said:


> i tried using ferrous sulphate in dropping gold, all i get is the very few fine white colored dust, that i believe, the powder ferrous sulphate i mixed with my gold chloride..... and its not dropping any gold i extracted from 3 cpus and few pins. i used 1:4.5 nitric and muriatic acid, neutralize the solution with urea, then used ferrous sulphate with out success of dropping. Pleas help. I used the ferrous sulphate that you buy in a drugstore, in capsule form, just extracted this white powder and i just drop it straight to my gold chloride....is this ok? or any ferrous chloride you can suggest.


There may be several reasons why you got no gold. One of them is the distinct possibility that you had none in solution. When you process base metals and gold combined, using AR, which I speak against on a regular basis, you risk that very thing. 

Here's the deal. 

As long as you have ANY base metal left un-dissolved, as the acid level diminishes, any values in solution will be cemented on the un-dissolved base metals. You may or may not recognize the now cemented values as gold in that if the solution is dirty enough, it may come down black. In such a case, your gold will have been removed in filtration. 

It is VERY important that you understand the significance of using stannous chloride for testing, and that you TEST at every opportunity, to insure that you know where your gold is. So you understand, we had a reader that felt there was no need to test. I contend that without testing, you are operating blindly. Stannous chloride is, for all practical purposes, the eyes of the refiner. Without its use, you generally have no clue what you have, nor where your values may be if they are not found in precipitation. I have now assumed the posture that a person that refines without using stannous chloride will receive no help from me----for they are not willing to meet me half way and do what they should be doing in the first place. 

You would expect very little gold from such a small amount of material, but you should be able to easily detect it in solution, and to identify the gold in precipitation. Using ferrous sulfate, the cloud that forms is usually a brown color, which clouds the solution almost instantly. It can take hours to settle.

I do not approve of your source of ferrous sulfate. It most likely has a filler added, which renders it fairly useless for the purpose of precipitation. 

In order for ferrous sulfate to function, it's important that it be pale green in color. As it oxidizes it changes to a light brown color (rust), and no longer contains the needed electron that precipitates the values from the chloride solution. I suggest you go to a large garden supply store and find a small bag of iron, intended for use on gardens. It should be marked as ferrous sulfate. It would be wise to inspect the product if at all possible, insuring that it is green. 

When you use ferrous sulfate, you will achieve very good results by dissolving an ounce of crystal in a small amount of water, then dripping in some HCl until the solution clarifies. The color will shift ever so slightly, and the solution will be clear of flocculence. It can then be poured to your filtered gold chloride solution, resulting in an instantaneous precipitation, assuming you have no free nitric present. 

While I mentioned an ounce of crystal, know that an ounce of crystal is capable of precipitating a troy ounce of gold. 

Again, be certain to test your solution, using stannous chloride, to insure that you have it all down. 

If none of this makes sense, I strongly suggest you stop what you're doing and read Hoke. Read the book until what she preaches makes sense to you. It will, by then, be well understood, and you won't have the questions you now have. 

Hope this helps. 

Harold

Oh, yeah! Welcome to the forum.


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## gengates (Apr 20, 2010)

Harold_V,

Many thanks! I just found a source of Ferrous Sulfate in the local garden supply, maybe this saturday ill try it. Since i am a beginner, and use only what available chemical i have locally here, i have not found a source yet of a gold testing chemical. It is very exciting indeed, i have no problem in AR dissolving all the metals (all is left are ceramics and plastic. I have filtered the solution. Also i have no problem in neutralizing the nitric acid by urea... this gold dropping is just my problem. Hoping that there is gold that i can see visibly at least. That will make my day already since am a beginner and first timer.

Ill post my update later.

thank you all!


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## gengates (Apr 21, 2010)

When you use ferrous sulfate, you will achieve very good results by dissolving an ounce of crystal in a small amount of water, then dripping in some HCl until the solution clarifies. 


Harold_v,

instead of HCl, can i use Muriatic acid?


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## Platinum (Apr 21, 2010)

Hcl is muriatic acid.


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## Harold_V (Apr 21, 2010)

gengates said:


> i have not found a source yet of a gold testing chemical.


Please accept the following comment in the spirit in which it is offered. 

Would you put on blinders, then drive your auto? 

That's what you're doing, processing without the ability to test. 

Do not delay getting stannous chloride. Until you have some, anyone that offers you advice may be leading you astray. You can not be helped until you know the nature of the help you need. You must know where your gold is before it can be recovered. Testing is how that is determined. 

I always used stannous chloride crystal to build my test solution, but the guys on this board have been promoting making it from a bit of lead free solder, which you will find to be 95% tin. A snippet dissolved in some HCl and you're good to go. Do not put it off. 



> It is very exciting indeed, i have no problem in AR dissolving all the metals (all is left are ceramics and plastic.


Your time will come. That is especially true when you learn to use proportioned amounts of acid, so you don't waste any. Do not consider that your one experience is representative-----it is not. Also, you need to learn the reasons why you are told to not dissolve base metals along with values. That is very much a part of learning to refine with acceptable results. 



> I have filtered the solution.



Yes. This time. What about next time, when you happen to include some tin in the mix?

You are being instructed in methods that avoid problems. Problems that you _will _ encounter, it's just a matter of when. Pay attention now, so you can avoid them, and so you will be well versed when they occur, already possessing the knowledge to work around the issue. 



> Also i have no problem in neutralizing the nitric acid by urea... this gold dropping is just my problem.


You can't claim you have no problem with urea if you have not recovered your values. What you can claim is that you have not recovered your values. The reason why is yet to be determined. You can do that by paying attention to what you're being told, not by second guessing the situation because you have jumped through a given number of hoops. 



> Hoping that there is gold that i can see visibly at least. That will make my day already since am a beginner and first timer.


That, of course, depends on how much you started with, and whether it ended up in your final solution, or not. You don't know if it did, or not. You must test to know. Your values could well be in the solids you removed in filtration. I don't know that they are, and I don't know that they're not. Again, you must TEST your solution. Mean time, do not discard anything. 



> Ill post my update later.



Hoping to hear a positive report. Mean time, read Hoke. Read Hoke again.

Harold


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## gengates (Apr 21, 2010)

I feel a little bit ashamed of myself on my postings and inquiries i made, but you're all right, ignorance of the topic you are interested with excuses no one....loud and clear, i have to read and read and read....and there are no shortcuts. but newbies all the time, wants shortcuts to their answers due to excitements, that includes myself. 

many thanks for everybody, for listening.


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## Platinum (Apr 21, 2010)

gengates said:


> I feel a little bit ashamed of myself on my postings and inquiries i made, but you're all right, ignorance of the topic you are interested with excuses no one....loud and clear, i have to read and read and read....and there are no shortcuts. but newbies all the time, wants shortcuts to their answers due to excitements, that includes myself.
> 
> many thanks for everybody, for listening.



Just keep reading and if you have any questions ask. There are not stupid questions, just stupid excuses for not asking a stupid question.


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## Harold_V (Apr 22, 2010)

gengates said:


> I feel a little bit ashamed of myself on my postings and inquiries i made, but you're all right, ignorance of the topic you are interested with excuses no one....loud and clear, i have to read and read and read....and there are no shortcuts. but newbies all the time, wants shortcuts to their answers due to excitements, that includes myself.
> 
> many thanks for everybody, for listening.


No need to be ashamed. Perhaps you should have seen me when I started refining---I could hardly contain myself. 

Unlike you, however, I had no one to whom I could turn for advice. Were it not for Hoke's book, I wouldn't have learned much. It is for that reason I promote her book. She alone is responsible for the little I know about refining. Her teachings were adequate to allow me to refine on a commercial basis until I retired.

I admire (and respect) your comment about there being no shortcut. If only the others would come to terms with that logic. 

Read Hoke! 8) 

Harold


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## flawlessfinish805 (May 26, 2010)

I have read through Hoke's book and it is very useful. I just dont know how well it works when applied to raw ore from a mine shaft or tailing pile. That is what I am working with. My friend inherited some gold mines that havent been worked since 1942. So I would appreciate some assistance in making an AR that will be pretty universal for what other elements my AR may encounter. 
I am currently using a method from a man A.K. Williams, but he is not detailed enough to finish the job. I have also been using sulfuric acid from the auto store instead of HCL. Which I will be receiving in the mail shortly. Here is what i have tried so far:
1. mix 4:1 sulfuric to nitric (sometimes i added h2o2, very small amount)
2. added my ore
3. let it stand over night
4. poured off acid into another container
5. added diluted 3 tablespoons ammonium nitrate to a quart of water
6. poured ammon. nitrate into AR
7. observed the AR turn slightly greenish and give off red-brown smoke
8. no mud..or slightly any mud precipitating
9. poured more ammonium nitrate
10. observed green-dark blue AR and precipitate seemed to be less now.

-precipitate is less than a "pinch" of sand or mud
-I never checked Ph
-i never changed the temperature

I know this is all wrong...or mostly wrong but can you (harold_v or any others who are knowledglable) telll me where i went wrong and maybe put me back on the right track. I have fire assayed this same material and it came back around 64oz/ton of precious metal. but i didnt seperate the metals so i dont know how much actual gold there was. but i could tell the was some palledium by the smokey look on my prill.


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## goldsilverpro (May 26, 2010)

Hydrochloric and sulfuric are not interchangeable when making up aqua regia. Sulfuric plus nitric is not aqua regia and will not dissolve gold. Instead of buying hydrochloric, it is much cheaper to buy muriatic acid from a hardware store. Muriatic is hydrochloric acid with a little lower purity.


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