# Help?



## badestb (Dec 22, 2021)

So, I've been digesting circuit boards, gold fingers, and pretty much anything I can get my hands on that are gold plated in nitric acid for a few weeks now. I keep getting this grey or silver substance at the bottom of my beaker which doesn't disolve into the solution and keeps clogging up my filters really badly... At first I thought it was silver but then realized it would be dissolved in solution... What is this stuff? What do I do with and about it?


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## FrugalRefiner (Dec 22, 2021)

Tin.

Dave


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## badestb (Dec 22, 2021)

Really? How do you know? I mean how would I know?


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## badestb (Dec 22, 2021)

It doesn't stick to my magnet in my magnetic stirrer at all so it can't be tin right?


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## Noggin (Dec 22, 2021)

Check out information on metastannic acid.


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## Swissgoldrefiner (Dec 22, 2021)

If i were you, i will filter the solution. Then test the liquid with stanous test and try to dissolve the remain ing powder in new batch with nitric.


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## badestb (Dec 22, 2021)

Swissgoldrefiner said:


> If i were you, i will filter the solution. Then test the liquid with stanous test and try to dissolve the remain ing powder in new batch with nitric.


I have tested the solution with sanous cloride and it stays clear, the isn't any gold in the solution. And the nitric acid is still digesting plenty of other metals still... I will try to find a picture of it or a video with it in it to show you what it's like...


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## canedane (Dec 22, 2021)

badestb Welcome to the forum. I am sorry to tell you are not ready to use chemicals yet, you have to study first and know what you are doing. Google is your freind here. If you cant find or understand an answer then use GRF, but try first your self. Merry xmas.​Henrik


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## Swissgoldrefiner (Dec 22, 2021)

badestb said:


> I have tested the solution with sanous cloride and it stays clear, the isn't any gold in the solution. And the nitric acid is still digesting plenty of other metals still... I will try to find a picture of it or a video with it in it to show you what it's like...


I think there is anyway nothing inside as gold. For gold you need to add the chlorhydric acid as well...


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## orvi (Dec 22, 2021)

badestb said:


> So, I've been digesting circuit boards, gold fingers, and pretty much anything I can get my hands on that are gold plated in nitric acid for a few weeks now. I keep getting this grey or silver substance at the bottom of my beaker which doesn't disolve into the solution and keeps clogging up my filters really badly... At first I thought it was silver but then realized it would be dissolved in solution... What is this stuff? What do I do with and about it?


Acid isn´t magic thing where you put all junk and stuff, and you fish out shiny gold bar 
Putting whole PCBs into nitric is generally a bad idea due to presence of tin (you learned hard way) and also iron/kovar and aluminium. These metals refuse to dissolve in nitric acid, and complicate the things.

More you separate the metals and materials, less messy and better yielding your procedure would be.

Picture of material will be good for making some advice that could potentially help.


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## FrugalRefiner (Dec 22, 2021)

badestb said:


> Really? How do you know? I mean how would I know?


You said you were putting "circuit boards, gold fingers, and pretty much anything I can get my hands on that are gold plated in nitric acid". Circuit boards have solder, and the main component of solder is tin. It doesn't dissolve in nitric and it clogs filters. So it's an educated guess.

You can know by studying the forum before you combine any more ewaste and acids. It takes a lot of commitment to learn how to do this properly. Start by studying what to do with the toxic waste you've created that now contains an unknown variety of heavy metals.

I'm not trying to be mean, but I want you to understand this tales a lot of study. You can start with my Tips for Navigating and Posting on the Forum thread.

Dave


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## Noggin (Dec 22, 2021)

Hoke’s book specifically the chapter on observing the effect of acid on tin and the concept of acquaintance experiments should move you past this hurdle quickly.


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## Yggdrasil (Dec 22, 2021)

I have seen it before and it will probably come again.
It is a English daily language thing.



> It doesn't stick to my magnet in my magnetic stirrer at all so it can't be tin right?


Tin-can and other daily objects with tin in them. --> magnetic because it is not made of tin, but rather steel/iron thinly plated with tin (Sn) or other non corrosive white metal.

Many seem to make this misconception.


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## badestb (Dec 22, 2021)

canedane said:


> badestb Welcome to the forum. I am sorry to tell you are not ready to use chemicals yet, you have to study first and know what you are doing. Google is your freind here. If you cant find or understand an answer then use GRF, but try first your self. Merry xmas.​Henrik


I don't know why you think I have been doing anything but studying, & a HARD crash course at that! With all due respect brother, I bet that there isn't one person who has done this gold recovery stuff in all of history who hasn't had to learn thru trial and error... Every single one of us has had questions throughout... But that's the joy of a site like this! It gives us a chance to come together, when we normally would have to struggle alone the whole way, and help each other through our mistakes... So I don't think you have any business judging me or telling me I shouldn't be using chemicals, who are you to make such a call? Then insult me more by telling me Merry Xmas? Wow! Thanks for welcoming a new person into the wonderful hobby, you really made me feel welcome!


canedane said:


> badestb Welcome to the forum. I am sorry to tell you are not ready to use chemicals yet, you have to study first and know what you are doing. Google is your freind here. If you cant find or understand an answer then use GRF, but try first your self. Merry xmas.​Henrik


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## badestb (Dec 23, 2021)

Noggin said:


> Hoke’s book specifically the chapter on observing the effect of acid on tin and the concept of acquaintance experiments should move you past this hurdle quickly.


I really appreciate that suggestion, I recently started to read that book and am grateful to be pointed in the right direction... Even as trivial as everybody appears to find my question. We thout questions, how am I supposed to learn?


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## Yggdrasil (Dec 23, 2021)

badestb said:


> I don't know why you think I have been doing anything but studying, & a HARD crash course at that! With all due respect brother, I bet that there isn't one person who has done this gold recovery stuff in all of history who hasn't had to learn thru trial and error... Every single one of us has had questions throughout... But that's the joy of a site like this! It gives us a chance to come together, when we normally would have to struggle alone the whole way, and help each other through our mistakes... So I don't think you have any business judging me or telling me I shouldn't be using chemicals, who are you to make such a call? Then insult me more by telling me Merry Xmas? Wow! Thanks for welcoming a new person into the wonderful hobby, you really made me feel welcome!


Now.
I kind of agree with CaneDane to some extent. Your questions and use of terminology indicate, but just indicate that you are not up to speed on certain areas.

It may or may not be just your use of terminology.
When it goes to the way he greeted you, well it was harsh and less than welcoming. His primary language is not English, so things may have been garbled in transmission. Anything else he can fill in for himself.

Your reaction was probably out of frustration, we have all been there, and the one thing that do not work, is biting back when corrected.
Suck it up and keep studying.

And not out of disrespect, I do wish you a Merry and fruitful Christmas.

Regards Per-Ove


Edit to add: 
Welcome to our forum by the way


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## MicheleM (Dec 23, 2021)

@badestb you wrote: "I don't know why you think I have been doing anything but studying". It is self-evident . I do not know if you tried to study but simply not enough. I suggest you to read ALL the threads on this forum before any attempts to recover precious metals.


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## Noggin (Dec 23, 2021)

badestb said:


> I really appreciate that suggestion, I recently started to read that book and am grateful to be pointed in the right direction... Even as trivial as everybody appears to find my question. We thout questions, how am I supposed to learn?


Don’t take that comment too much to heart. Lots of these threads seem to invite these. Where it’s justified is when someone is doing something highly dangerous or polluting. You’re not that guy imho. Welcome to the forum!


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## MicheleM (Dec 23, 2021)

In my opinion we should never underestimate the dangers coming from precious metals recovery and refining, the vast majority of reaction products are highly toxic.


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## Martijn (Dec 23, 2021)

Welcome to the forum Badestb. 

Dissving pcb's and gold plated items in nitric is a waste of time and money. 
Because to avoid metastannic acid (That grey white stuff you've created) you will first have to leach the solder off with HCL. 

Then to avoid creating weak AR while digesting with nitric, you will have to wash and rinse all HCL residue thoroughly. Porous materials will be nearly impossible to rinse good enough. 

And the tiny amount of plated gold (microns thick) on a solid piece of basemetal is not worth the chemical waste created and acids used to recover the gold. 

Acid peroxide would be a better way imo.

Martijn. 

And yes, judging your approach to this suggest you need to study a lot more. 
And ask away if you have a question. 
Have you read Dealing with waste? 








Dealing with Waste


I have been roaming this site for a few weeks, and with Hoke's book on it's way (fyi Harold) and Steve's DVD's I should be ready to start recovering pm's here pretty soon. I do have concerns about how to correctly deal with wastes. I am looking for some insight into how you guys deal with this...




goldrefiningforum.com


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## nickvc (Dec 23, 2021)

This really isn’t a comment aimed only at you but to those who do very similar things to start , you are not the first and I very much doubt the last .
The one thing to bear in mind in recovery and refining is that many of the chemicals we use are toxic and can and do cause serious and sometimes permanent damage which is the main reason we strongly advise new members to read and study and not blindly mix chemicals without the knowledge of what the result will be , the metals we are after are some of the least reactive elements on the planet and need highly reactive acids or alkaline elements to be able to react . 
Bottom line is do not experiment with chemicals unless you have a damn good idea of the outcome it will end badly in many cases.


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## Dougplogan (Dec 23, 2021)

Most e waist has tin on or it it. I learned the hard way trying to desolve metal pins. You shouldve soaked in hydrochloric acid to wash the tin off first. My fear or reason for going straight to nitric was fear of desolving gold. But after you wash as best you can with water any gold that does desolve at first which will be a small amount will cement back out onto desolving copper. Provided it was only contaminated with tiny amount of hydrochloric acid. Any ways what worked for me was just to continue desolving all base metals. At that point I decanted and washed with water over and over. No it didn't get all of the white metastannic acid but it did help to remove some. Then I went straight to aqua regia. The metastannic acid didn't desolve in the aqua regia. Instead of filtering I leached the liquid off with two shoe laces instead. It was slow but worked for me. I'm very new to this and their are other better ways I'm sure. Use patience and whatever you do. Do it in tiny test batches that way you know if you can pull it off or not without loosing whole batch


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## orvi (Dec 23, 2021)

badestb said:


> I don't know why you think I have been doing anything but studying, & a HARD crash course at that! With all due respect brother, *I bet that there isn't one person who has done this gold recovery stuff in all of history who hasn't had to learn thru trial and error...* Every single one of us has had questions throughout... But that's the joy of a site like this! It gives us a chance to come together, when we normally would have to struggle alone the whole way, and help each other through our mistakes... So I don't think you have any business judging me or telling me I shouldn't be using chemicals, who are you to make such a call? Then insult me more by telling me Merry Xmas? Wow! Thanks for welcoming a new person into the wonderful hobby, you really made me feel welcome!


It was an educated view on what you have done  we make mistakes, but point of all of you consider "insults" is to focus you more on learning basic principles and consequences of certain chemical reactions. Part with resolving mess created by going with first idea that come to your mind could be practically completely skipped, if you focus on research.
Almost everything we do about refining was done before. You should think about it everytime you are going to process some boards, CPUs, pins, MLCCs etc... Best thing about this forum = you can search key words and find immense quantity of suggestions on how to do it the best and how to certainly not.
With so much available knowledge on the internet (also visualized like YT videos) and espetially here on GRF, you dont need to go through trial and error. It could take few hours of learning, but it can save you whole lot of frustration and money/time.
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Moralizing aside. I dont exactly know how cheaply you could access nitric acid, but to dissolve huge ammounts of base metals, you will need a good bit of it. Pieces of aluminium and iron could be hard to dissolve and you will end up with bunch of crap at the end. 
If the foils are relatively "attached" to the boards (still), take them out of the soup and carefully wash them with water. You can throughly wash the boards from nitric (like immersing in the bucket of water) and continue with HCl/air or AP to remove the rest of base metals - much more advised.

If too much foils fell from the boards, it would be more painful. Try not to shake and stirr the container too much, or you will crush the foils to small pieces. Foils could be separated to some extent by pouring the metastannic goo through fine sieve/strainer (not made of metal ofc) - the white goo should pass, foils will rest. If there are too many small golden pieces still after several "strainings", then you will need to filter the metastannic anyway...

With simple gravity filtration it would took ages, but it is what it is. If you have vacuum pump and vacuum filtration setup, it would be easier. As the gold is not leached and is in form of foils, you dont necessarily need filter paper. Some old cloth or non-wowen texile could also help speed it up if used instead of paper (but acid could eat/disintegrate it when soaked for too long).
When you retrieve the foils, cover the goo with HCl and add minute nitric, heat it till all foils dissolve and filter. Should work to make gold go into the solution.


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## Noggin (Dec 23, 2021)

MicheleM said:


> In my opinion we should never underestimate the dangers coming from precious metals recovery and refining, the vast majority of reaction products are highly toxic.


To my point though, I think you'd be hard-pressed to identify the danger here. His biggest issue is not realizing that the free nitric would be metabolized almost right away. That's hardly a reason to tell him to put down the chemicals or read the entire forum. 
I have not been a contributor here for long, but I embrace teachable moments respectfully and that's my thing.


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## MicheleM (Dec 23, 2021)

@Noggin I can't agree with you because we don't know what he is doing exactly : no information except that he put some electronic boards in acid and make a mess. He doesn't know enough and If you don't know enough what you are doing the dangers can be everywhere: no googles, no gloves, no respirator, working inside, pets or kids nearby just to name a few. I gave a suggestion: read first, to help him in his path. He is free to do what he think is right


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## orvi (Dec 23, 2021)

Noggin said:


> To my point though, I think you'd be hard-pressed to identify the danger here. His biggest issue is not realizing that the free nitric would be metabolized almost right away. That's hardly a reason to tell him to put down the chemicals or read the entire forum.
> I have not been a contributor here for long, but I embrace teachable moments respectfully and that's my thing.


There are much more things to consider aside of just nitric being metabolized - nitrates are not the healthiest anions known. Nitric create very awful burns which are painful and heal very slowly. Nitrogen oxides are certainly created in the process, which are another big bad thing. Inhaling these vapors could lead to serious health issues - immediate and also prolonged. Lead from solder in soluble form is another thing. Cautious approach is the best you could do when inexperienced, but the whole situation of putting boards straight into the acid is telling me that good portion of accessible knowledge was not applied. I am just assuming here, to be clear.

21. century. We dont need to go through trial and error with well resolved and known issues.


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## Noggin (Dec 23, 2021)

orvi said:


> There are much more things to consider aside of just nitric being metabolized - nitrates are not the healthiest anions known. Nitric create very awful burns which are painful and heal very slowly. Nitrogen oxides are certainly created in the process, which are another big bad thing. Inhaling these vapors could lead to serious health issues - immediate and also prolonged. Lead from solder in soluble form is another thing. Cautious approach is the best you could do when inexperienced, but the whole situation of putting boards straight into the acid is telling me that good portion of accessible knowledge was not applied. I am just assuming here, to be clear.
> 
> 21. century. We dont need to go through trial and error with well resolved and known issues.


You and Michelle are completely right. He may have made other errors. But he didn't bring any dangerous practices up. And nor would I impute those on him automatically. Anyone who knows to use nitric to dissolve metal has been warned at the same time of being instructed. If someone mentions that they are boiling piranha solution in a coffee mug, I'm right there with you.


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## butcher (Dec 23, 2021)

I am glad someone was there to slap me up against the head once in a while when I was young.

If I am sleepwalking towards a busy freeway, I would just hope someone would be kind enough and take the time enough, from their busy day to slap me up the side of the head, to wake me up, it may hurt less than all of those fast moving trucks on the freeway.


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## orvi (Dec 24, 2021)

Noggin said:


> You and Michelle are completely right. He may have made other errors. But he didn't bring any dangerous practices up. And nor would I impute those on him automatically. Anyone who knows to use nitric to dissolve metal has been warned at the same time of being instructed. If someone mentions that they are boiling piranha solution in a coffee mug, I'm right there with you.


Yes, you are correct - I am a bit "overcaring". That is probably my habit from hours and hours of teaching chemistry. Being over-cautious about what your class is doing, hence i am responsible for them... Not all of them can figure out obvious dangers, often doing all kinds of dumbassery, despite they have complete guide and written step by step procedures. 
I am just used to it, so maybe i am overreacting in other situations


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