# Gold Precipitation



## PGM-Au-Ag

Which is a better regent for precipitating Au from AR, Sodium Nitrite or Sodium Bisulfite and why? Thanks.


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## Geo

you havent tried any processes yet have you? if not, then dont do anything until you read Hoke's book "refining precious metal waste". you need to learn about what reagent does what.

sodium nitrate does not precipitate gold. SMB (sodium metabisulfite) is the preferred precipitant for gold on the forum.

dont do something that will endanger your self or someone else before you study what you want to do and how to do it.


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## nickvc

Seconded.

Don't take offence but refining isn't a chuck it in a bucket add a few chemicals, leave it and go to the bar, come back drain it off and add another chemical and hey presto gold.
Take the advice offered and study and read Hoke until it makes sense,also read the safety section and be prepared to spend many hours doing yet more reading before you attempt any recoveries or refining.
If you have values sitting around they are safe unless you dissolve them and then can't recover them,take your time and you can be successful and that button will be yours.


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## butcher

I have read where sodium nitrite is used to precipitate gold and works something like copperas, and I also understand the solution should not be too high of an acid content (excess acid), I have never used it, so I really do not know any details.

I have used sodium bisulfite and sodium metabisulfite, and they work well, copperas (ferrous sulfate) also works well.

Geo, note, he asked about sodium nitrite NaNO2, not sodium nitrate NaNO3.

Hoke also mentioned the use of sodium nitrite to precipitate gold from aqua regia.

I agree 100% study Hokes book, it is your key to understanding the processes.


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## PGM-Au-Ag

I was hoping that the Bisulfite precipitation would not be as fine a powder as the Sulfite. 

Does Hokes 's book add more detail than Ammen? 

Using Sodium Sulfite does require the solution to be free of Nitric and a ph of at least 5.5. If ph levels do not have to be as high with Sodium Bisulfite then that is another advantage. In addition, I do not know if the Nitrite produces the SO2 gas, which is desirable as the Bisulfite does.


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## johnny309

It is in Hoke's book


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## goldsilverpro

Geo, he did say sodium nitrite and not nitrate. Sodium nitrite can be used to precipitate gold.


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## Geo

after re-reading i understand i mis-read.  

PGM, i apologize, it happens sometimes when ive been up twenty hours.


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## butcher

Hoke page 56


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## PGM-Au-Ag

That's ok Geo, ain't nobody perfect.


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## Harold_V

PGM-Au-Ag said:


> I was hoping that the Bisulfite precipitation would not be as fine a powder as the Sulfite.


How the gold comes down may be a function of the degree of concentration, although I'm not sure that's true. Here's why I say so. 

I routinely re-processed all of my gold, and did so for years. I did it by repeating the aqua regia method, and used SO2 for precipitation. I routinely processed in lots that were approximately 75 ounces in size. The solution was generated such that I ended up with four four liter beakers, each containing, more or less, ¼ of the 75 ounces. The solution was evaporated to just one liter in volume, to which I'd add about three liters of ice, just prior to precipitation. 

The gold from this procedure came down dense and blond (very pale in color) and would settle in just a minute or two. The only exception would be if the solution got too hot, and ceased precipitating. When that occurred, I'd add a little more ice, to cool the solution slightly, then commence precipitation. The solution, now quite dilute, would precipitate much finer particles. I can only speculate that it was because of being greatly diluted. 

You may wish to give concentration a try, but, remember, precipitation with SO2 is an exothermic reaction, so if your solutions are too highly concentrated, precipitation will cease, just as it did for me. 

Harold


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## goldpete

please help me . i soaked some gold pins in nitric acid over night , then rinsed all the gold in water thoroughly before adding them to AR. i ended up with a lovely yellow solution and i really thought it was finally working out for me , but when i added the SMB , it went black then changed to atransperrent green.
i continued to add SMB but all it did was lighten in colour and no gold dropped.
so thismorning i added some aluminium and it smoked and changed to a dark brown solution and i see dark sandy dust on the bottom.
is that gold ? and why did my AR go green instead of dropping the gold ?


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## patnor1011

How did you neutralize nitric in your AR before adding SMB?
Here is your problem.


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## goldpete

i didnt . i thought thats what SMB does.
so if i had heated the AR for about half an hour , then added hcl then heated again , would that be ok to then add SMB ?


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## butcher

goldpete,

Before doing anything more I suggest you study Hokes Book, other wise your just going to be stumbling from one mistake and mess and into the next mess, fumbling around looking for where all of your gold has disappeared to, after you dissolved it.

I feel if you do not do the studying before you begin your just wasting your gold and time.

You are looking for the evaporation process to remove excess nitric acid, you can find the process in Hokes book, (notice in her book she uses a steam table, which would not boil the solution while dispelling the free nitric acid from solution, you can use other heat sources as long as you can control the temperature, I imagine you also have an excess of SMB in this solution.


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## goldpete

ive been watching so many videos on youtube and they all make it look so easy , and ive read so many foums . im tying to oganise all the info but it seems im confused somewhere along the line


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## tek4g63

Goldpete.
Forget the you tube videos for now. Most are fake or wrong, and the ones that are real should only be watched after you have built a working knowledge of the art of recovery and refining. Also from this point on forget reading any other forums or google searches. You have found the right place, that is as long as your willing to learn. 

Use the search function on this forum to answer most of your questions.

Put your mess away safely, for now, and study your butt off. As long as you don't throw anything away your gold will still be there waiting on you. 

There are much better ways to dissolve your gold foils. Ways that you don't have to rid the solution of free nitrates. Like HCL/CL (hydrochloric acid / bleach ) it will dissolve your recovered foils and all you will have to do is leave it alone for 24 hours to let the chlorine evaporate out before adding SMB. 

Your on the right track, please stay on it. Study, and study more before asking questions, then when you have a question, ask it before you try anything. I did this and my first try at recovery and refining went text book perfect. It's all thanks to the members of this forum, the only place I get my information.

Can't wait to see that first button.


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## goldpete

tek4g63 said:


> Goldpete.
> Forget the you tube videos for now. Most are fake or wrong, and the ones that are real should only be watched after you have built a working knowledge of the art of recovery and refining. Also from this point on forget reading any other forums or google searches. You have found the right place, that is as long as your willing to learn.
> 
> Use the search function on this forum to answer most of your questions.
> 
> Put your mess away safely, for now, and study your butt off. As long as you don't throw anything away your gold will still be there waiting on you.
> 
> There are much better ways to dissolve your gold foils. Ways that you don't have to rid the solution of free nitrates. Like HCL/CL (hydrochloric acid / bleach ) it will dissolve your recovered foils and all you will have to do is leave it alone for 24 hours to let the chlorine evaporate out before adding SMB.
> 
> Your on the right track, please stay on it. Study, and study more before asking questions, then when you have a question, ask it before you try anything. I did this and my first try at recovery and refining went text book perfect. It's all thanks to the members of this forum, the only place I get my information.
> 
> Can't wait to see that first button.


thankyou so much for your help , and i will follow what you say to the letter. , i think i had a win today . cuz i put some aluminium into the aqua regia that i talked about before and it fizzled and smoked and turned a purplish colour , then i heated it till it reduced half its quantity , then i put HCL into it till it reached its original volume and it has returned to the deep yellow . im so excited ....... i kept heating it till it reduced by half its volume . so now i have about 100ml of deep yellow solution. what do i do now?


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## maynman1751

> so now i have about 100ml of deep yellow solution. what do i do now?



Put a cover over it and do your reading and studying. It will be much more beneficial to you if you find this answer out yourself rather than someone telling you what to do next. Your gold isn't going anywhere. Cool your jets and take your time to learn proper procedure. It's a lot better than messing up and then trying to figure out how to fix it. Listen to the advice given and you'll be on your way!


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## goldpete

maynman1751 said:


> so now i have about 100ml of deep yellow solution. what do i do now?
> 
> 
> 
> 
> Put a cover over it and do your reading and studying. It will be much more beneficial to you if you find this answer out yourself rather than someone telling you what to do next. Your gold isn't going anywhere. Cool your jets and take your time to learn proper procedure. It's a lot better than messing up and then trying to figure out how to fix it. Listen to the advice given and you'll be on your way!
Click to expand...


ok thanks .just out of curiousity ,did i do good returning the solution back to a deep yellow


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## maynman1751

goldpete said:


> maynman1751 said:
> 
> 
> 
> 
> 
> 
> so now i have about 100ml of deep yellow solution. what do i do now?
> 
> 
> 
> 
> Put a cover over it and do your reading and studying. It will be much more beneficial to you if you find this answer out yourself rather than someone telling you what to do next. Your gold isn't going anywhere. Cool your jets and take your time to learn proper procedure. It's a lot better than messing up and then trying to figure out how to fix it. Listen to the advice given and you'll be on your way!
> 
> Click to expand...
> 
> 
> ok thanks .just out of curiousity ,did i do good returning the solution back to a deep yellow
Click to expand...


I'm not sure. You need to test with stannous to see if there's gold in solution. That's why stannous is so important. It's your eyes into the solutions. It tells you what you have or don't have. Do a search for making stannous. It's very simple and very necessary.


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## goldpete

goldpete said:


> maynman1751 said:
> 
> 
> 
> 
> 
> 
> so now i have about 100ml of deep yellow solution. what do i do now?
> 
> 
> 
> 
> Put a cover over it and do your reading and studying. It will be much more beneficial to you if you find this answer out yourself rather than someone telling you what to do next. Your gold isn't going anywhere. Cool your jets and take your time to learn proper procedure. It's a lot better than messing up and then trying to figure out how to fix it. Listen to the advice given and you'll be on your way!
> 
> Click to expand...
> 
> 
> ok thanks .just out of curiousity ,did i do good returning the solution back to a deep yellow
Click to expand...

 

well thatwas intereting , i read the book , very informnative indeed


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## dcorley001

Don't know if I'm more impressed or jealous. Wish I could read and absorb an over 300 page technical manual in one night...


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## goldpete

well it was easy because most of the book didnt apply to me ............. im not interested in aquriing the silver or paladium or any other metals . so i scrolled down . then i went past where it talked about other types of gold such as green gold , white gold etc and i scrolled on past where it talked about chemicals and techniques i dont have.

i have notes stored next to the parts that relate to me . for example , the soaking in nitric ,
mixing and using the aqua regia,
avaporating the nitric,
dropping the cold ( which didnt help becaue im using smb instead of copperas)
washing the gold
and finally the melting of the gold


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## qst42know

You missed some very important information. 

These other metals are closely associated with gold and show up often. Lead, silver, and platinum group metals all show up in e-scrap. When they do you need to know how to deal with them whether you want them or not. You will fail to achieve an acceptable degree of gold purity if you don't learn what Hoke teaches to exclude these other metals.


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## Harold_V

What qst42know said.
If you short-change the reading of Hoke's book, you're going to miss a great deal of information that relates to processing gold. You, above everyone else, will pay a price for that decision. 

I strongly recommend you read the entire book, then do it again. Do it until you UNDERSTAND what she teaches. It serves no purpose to go through the motions, then come away without an understanding. It's all interrelated----so if you choose portions you _think_ you need to know, you're going to have an endless supply of questions, not understanding why things turn out as they do, and that's assuming you achieve some degree of success. 

You can't learn to play the piano by practicing only select notes. You must learn all of them. Everything in her book is important to you, whether you recognize that fact, or not. 

Harold


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## Nur

Hello everybody,
I am student from Malaysia. I am doing research in environmental impact of recycling gold from e-waste. I cooperate with one of companies in Malaysia. However, some data is consider as confidential. I really need the assumption amount of chemicals they use to analyze the environmental impact for producing gold from e-waste. I really appreciate if expertise from this forum can help me. The company have used nitric acid, hydrochloric acid, sulphuric acid, sodium hydroxide, zinc dust and zinc ingot in acid dissolution process. What I know from literature, nitric acid and hydrochloric acid is aqua regia, sulphuric acid can be used for leaching copper,zinc dust and zinc ingot used to drop palladium and silver. I don't know the function of sodium hydroxide. After acid dissolution, precipitation process is needed but this company don't give me any data including the name of chemicals for precipitating gold, copper, silver, palladium and platinum. Everybody know what are the chemicals that may can be used for precipitating all metals and the amount/ratio of assumption for each precipitators? Is it possible that the sodium metabisulfite is used for precipitating gold in the acid dissolution mixture?or iron (III) chloride more suitable to used for precipitating gold?How about palladium, platinum, silver and copper?Really need your help.


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## Palladium

Here you can find all the answers :arrow:


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## GoldDen

You say that 'here you can find all the answers'. I have read loads of questions on here that are left ignored or (un)answered with a rather unhelpful "read the book". If this is supposed to be a forum then it would be nice if questions are actually answered and a brief explanation of the solution given. 

If this forum just exists to massage some member's egos you may as well replace the forum with a message "I know the answers 'cos I'm really really clever but I'm not telling stupid you ! Read Hoke's book, re-read Hoke's book, it is all in Hoke's book...  " 

Yes great thanks ! While the process maybe totally covered in that book, however, as the materials vary it would be nice if someone did take the time to explain why the solution produced a white/grey powder instead of black, or why it went blue instead of yellow... you can't get that level of support from a book.

So is this a forum or a self help group for people insecure in their intellectual abilities that need some mutual reassuring ? 

I had to bring this up otherwise this forum will waste away and die off, have you seen how many people don't get a real answer and never come back ?


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## patnor1011

GoldDen said:


> You say that 'here you can find all the answers'. I have read loads of questions on here that are left ignored or (un)answered with a rather unhelpful "read the book". If this is supposed to be a forum then it would be nice if questions are actually answered and a brief explanation of the solution given.
> 
> If this forum just exists to massage some member's egos you may as well replace the forum with a message "I know the answers 'cos I'm really really clever but I'm not telling stupid you ! Read Hoke's book, re-read Hoke's book, it is all in Hoke's book...  "
> 
> Yes great thanks ! While the process maybe totally covered in that book, however, as the materials vary it would be nice if someone did take the time to explain why the solution produced a white/grey powder instead of black, or why it went blue instead of yellow... you can't get that level of support from a book.
> 
> So is this a forum or a self help group for people insecure in their intellectual abilities that need some mutual reassuring ?
> 
> I had to bring this up otherwise this forum will waste away and die off, have you seen how many people don't get a real answer and never come back ?



I can assure you forum is not going to die. This type of answer come to what can be called basic question. If someone ask basic question it mean he does not know what he is doing. No answer is going to help him unless he get a grip on pretty basic simple things. Whoever struggle with these should find different hobby. 
Recovery and refining is so complex that unless you are willing to put in considerable amount of time for studying you will fail and while failing you are going to endanger yourself and everyone around you.


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## FrugalRefiner

GoldDen, The Tips for Navigating and Posting on the Forum thread may help you understand how this forum works. Insulting members in your first post isn't a great way to make friends.

Dave


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## GoldDen

I don't want to belittle these processes, but come on it is hardly THAT difficult. it is not SO COMPLEX. Yes, it can be dangerous, but surely no more so than, say, gas welding ? Why make it sound like you need a higher degree in chemistry to do this ? If people on here wanted to learn about chemistry then I would really NOT recommend Hoke's cook book, but take a comprehensive Open University degree course.

The processes are not that tricky, When refining I estimate the approximate amount and, yes, it gets sloshed in. I am not going to titrate tiny drops at a time into a 5L solution, and don't tell me you do either. 

It strikes me that most posters have A specific problem (too much bleach, not enough SMB, too fine gold powder, strange sediments, unexpected colours, poor filtering, etc). They are looking for a 'top tip' to correct the problem. I suspect that the 'gurus' on here are people that work in a scrap that have picked up a little chemistry, I really doubt that anyone has a higher degree in chemistry, or possibly even a first, however, where they score is they have the HUGE advantage of loads of experience. Some of them must have come across a similar problem in the past and eventually they found a way to correct it (or not and we can all benefit from finding the solution).

So why don't these "gurus" pass on some of this knowledge gained through experience, trial and error ? It beats just telling everyone to go off and read a book. " They will be better chemists if they work it out themselves !" Possibly, but if that is your goal then host a tutorial page to teach people chemistry, why have a gold refining forum ? 

The forum may not die off as there will be an old core of 'experts' mutually feeling good about their knowledge as the elite, but it is a great shame that the site is not growing anywhere near as it should given the massive surge in people refining gold these days... 

Just reading through this thread I could list half a dozen members that with encouragement could have learnt and become contributors in the future, instead they seem to have vanished.


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## 4metals

GoldDen,

Cute name, a little play on words, you gave it some thought. 

Too bad you didn't give as much thought to being a member here. You came here and after half an hour as a member you're telling us this forum will waste away and die off. Hmmmm.

It is my opinion that you have come here to cause more trouble than to learn. I happen to have an advanced degree in chemistry as do others here. Unfortunately my degree is not in psychology, if it were, I might consider your presence here entertaining, instead I consider your presence here more trouble than you are likely worth. So I am banning you. I hope you at least downloaded the book from the library because that will be where you will be learning, not here anymore.


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## Anonymous

Aww bless.

Edit: for those who have PMed me or phoned me and asked if my comment was some Brit expression yes it is. It was based on the fact that I thought that 4Metals handled that extremely well, given that the guy was a douche. 8) 8) 

sorry for any confusion.

Jon


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