Sulfamic acid

[piperpod]

So like if you had 10 lbs of pins. And we’re doing smaller batches , can you just keep adding more pins till no reaction…

 

[Yggdrasil]

So like if you had 10 lbs of pins. And we’re doing smaller batches , can you just keep adding more pins till no reaction…

Welcome to us.
Your question hints that you are new to this.
So wait with the chemicals until you have studied some.

And yes and no to your question, you will discover when studying.

Here is some material for you.

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

Forum rules : https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/post-327766

 

[orvi]

So like if you had 10 lbs of pins. And we’re doing smaller batches , can you just keep adding more pins till no reaction

Depends on how you process them. If you process by plain nitric, then you can eventually discard also the juice with active acid. But for AR processing, this is a good technique. With few tweaks of course.

Truth is, if you have active AR, then letting it sit over unreacted material is best way how to denox and simultaneously cement the gold and other PMs on the remains of pins

 

[piperpod]

Depends on how you process them. If you process by plain nitric, then you can eventually discard also the juice with active acid. But for AR processing, this is a good technique. With few tweaks of course.

Truth is, if you have active AR, then letting it sit over unreacted material is best way how to denox and simultaneously cement the gold and other PMs on the remains of pins

Yes I mean using AR, what kind of tweaks ….

 

[eaglekeeper]

So like if you had 10 lbs of pins. And we’re doing smaller batches , can you just keep adding more pins till no reaction…

There's Lowes, Home depot and Ace hardware all over St Louis. You should have no problem finding Sulfamic acid.



or

 

[orvi]

Yes I mean using AR, what kind of tweaks ….

Cheapest de-noxing is with more material. There are some things to consider - if it is plated stuff, plating should be scratched, or base metal should be somewhat exposed to react with AR. If AR is at least hot to touch, nitric will be fully spent in matter of few hours. Holding the reaction at 80+°C helps to speed this up, you crank it near boiling at the end and you are basically done. Test with stannous, simmer to pack the precipitated PMs, let it still off heat for hour or so and you are ready to decant/filter the barren liquid and continue with stuff that remained.

Eventually, you will need sulfamic acid to denox. If you are hesitant to use sulfamic, there are some other options - like cementation+denox on solid copper. This is very nice method for concentrating gold to some workable material, it is relatively fast when hot... But you add significant copper to the waste. You also can neutralize the acid and then cement... But this I don´t recommend, it does not work that OK with various material feeds.

 

[Sunnyket]

It also depends in what form the gold is. If it is chunky, or shot to the water, than yes, you will need AR boiling to dissolve it. On the other hand, if it is gold precipitate from say SMB reduction, you does not need nitric at all. Acquire hydrogen peroxide and go with it. No de-NOxing needed afterwards. Just let the beaker with hot liquid open for few minutes and all chlorine and oxygen just escape out. And if not, SMB will very easily kill the chlorine in order of miliseconds

Thanks orvi for details

 

[Sunnyket]

It is somewhat tricky to use right ammount, and it takes too much time sometimes. Good technique is use less, then pour pregnant liquid and dissolve the rest. Little bit of nitric isn´t that catastrophic, SMB will kill it before dropping the gold, but the solution should be at least hot to the touch, otherwise reaction of nitric and SMB can have long induction period and liquors can eventually erupt gasses.

Convenient way is to make slurry of SMB (does not need to be dissolved truly), stir the pregnant hot liquid vigorously and pour the slurry in at rate that manage the controlled reaction.

Thing is, you does not need to de-NOx specifically with sulfamic acid, sulfite or SMB can do it too, but they are basic. This means, you are neutralizing your acid to begin with. Sulfamic acid is acidic. Of course, you can add more acid at beginning of gold drop there are many possibilities...

Cheapest de-NOxing agent and gold reducer is sodium sulfite. You grab still hot AR solution, make sulfite slurry and slowly pour it in with stirring. Be careful as reaction can be vigorous with eruption of gas - if you have excess nitric in. Do not use dry powder, as it is very wasteful technique. Particles of sulfite/SMB will start to hiss and are taken to the surface by the generated bubbles. This means, you will spend the acid in the place of contact, and simultaneously waste active reagent to the air - SO2. Slurry reacts under the level of liquid, so the SO2 generated is really adsorbed to the liquor. This works only when not overwhelming excess of nitric was used. Otherwise, it will take unhealthy ammount of SMB/sulfite to do this and that will severly deplete free acid in the juice. Causing silver or orther chloride resdues to come out of solution.

Of course, you will need to re-refine obtained gold. But it is much quicker than other techniques.

Thanks for this, it helps alot

 

[Sunnyket]

That was what I said.
If you use only the amount of Nitric needed or just a little more.
The SMB will take care if it, no need to use Sulfamic.

Orvi gave you some good advice, in the small scale it is practical to use the correct amount, if you are going bigger it gets more complicated as time becomes an driving factor.

Yes sir,
it means actual gold weight to nitric ratio is must be accurate. ?

I did Silver (gold plated silver ornaments) refining and after refining silver i got some dust residue that contains gold. In this case what will you do?

Please reply

 

[Yggdrasil]

Yes sir,
it means actual gold weight to nitric ratio is must be accurate. ?

I did Silver (gold plated silver ornaments) refining and after refining silver i got some dust residue that contains gold. In this case what will you do?

Please reply

No use it on the dissolved Gold as is.
But as always best if there are no excess.
How do you know there are Gold in the residue?
Anyway, if it is plating dissolve in HCl/Bleach or HCl/Peroxide. Make sure it is acidic and drop as usual.

 

[Sunnyket]

No use it on the dissolved Gold as is.
But as always best if there are no excess.
How do you know there are Gold in the residue?
Anyway, if it is plating dissolve in HCl/Bleach or HCl/Peroxide. Make sure it is acidic and drop as usual.

Residue contains gold approx 20%-30% of weight there are other metals too in that residue

 

[Yggdrasil]

Residue contains gold approx 20%-30% of weight there are other metals too in that residue

How do you know?

 

[Sunnyket]

How do you know?

I've done multiple times Aqua regia(different batches ) with this type of stuff and approximately i get that percentage of gold in residue

 

[Yggdrasil]

I've done multiple times Aqua regia(different batches ) with this type of stuff and approximately i get that percentage of gold in residue

Ok, so what have you changed since you are asking now?
How was your Stannous then?

Anyway it is plating is it not?
Then any method of dissolving will do, AR is not necessary.

 

[Sunnyket]

Ok, so what have you changed since you are asking now?
How was your Stannous then?

Anyway it is plating is it not?
Then any method of dissolving will do, AR is not necessary.

I'm beginner in processing.. Only one method i know that is AR so I'm curious what other effective methods
Thanku

 

[Yggdrasil]

I'm beginner in processing.. Only one method i know that is AR so I'm curious what other effective methods
Thanku

Foils is much better to process in HCl/Peroxide, HCl/pool Chlorine or HCl/Bleach(Sodium Hypochlorite).
I prefer the two first, since they don't neutralize the HCl.
Dropping the Gold is the same. SMB, Ascorbic, Oxalic or what ever suits your needs.

 

[Sunnyket]

Foils is much better to process in HCl/Peroxide, HCl/pool Chlorine or HCl/Bleach(Sodium Hypochlorite).
I prefer the two first, since they don't neutralize the HCl.
Dropping the Gold is the same. SMB, Ascorbic, Oxalic or what ever suits your needs.

HCL peroxide dissolve gold?