# Excess Nitric, de-nox with sulfamic acid?



## Hartbar (Feb 17, 2022)

I’ve seen where sulfamic acid is used to de-nox excess nitric in AR, prior to dropping for gold powder with SMB.
Curious if sulfamic can be used to to the same in Silver/copper nitrate after dissolving in nitric, prior to dropping with HCL or salt?
Thanks


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## goldandsilver123 (Feb 17, 2022)

No it can't. You need chloride ions for sulfamic to work properly, also it generates sulfate íons that you precipitate silver as silver sulfate.

Excess nitric is not a problem for silver.


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## Hartbar (Feb 17, 2022)

Thanks, is it advantageous to get all the nitric acid used up, by adding more silver with heat as a way to use all the nitric before the next process.
I see people do that with gold beads in AR


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## arthur kierski (Feb 18, 2022)

Hartbar said:


> I’ve seen where sulfamic acid is used to de-nox excess nitric in AR, prior to dropping for gold powder with SMB.
> Curious if sulfamic can be used to to the same in Silver/copper nitrate after dissolving in nitric, prior to dropping with HCL or salt?
> Thanks


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## arthur kierski (Feb 18, 2022)

i use Urea to denox excess nitric acid---never used sulfanic--regards Arthur Kierski


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## arthur kierski (Feb 18, 2022)

arthur kierski said:


> i use Urea to denox excess nitric acid---never used sulfanic--regards Arthur Kierski


i did not read your post completelly--- i use ura to denox excess nitric acid from ar----not for silver nitrate extraction,i do not needed


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## orvi (Feb 18, 2022)

From common silver salts, only nitrate has good solubility in aqueous solutions (and also perchlorate, but considering explosion hazards and cost of perchloric acid, it has no use in refining).

If you add sulfamic acid to silver nitrate/nitric acid solution, you will precipitate some of the silver as silver sulfamate or sulfate (silver sulfate has low solubility in water = around 8g/L).

I will not recommend to destroy excess nitric acid this way.

Depending on the next steps of your process, i will advise to add more silver to the solution and boil it till all nitric acid is consumed.
If you do not have more silver for this, you can sacrifice some extra copper - if you intend to cement the silver in the next step. Cementation of silver from solutions containing just a small ammount nitric acid is doable, but in order to speed up the consumption of the acid, stirring and heating is necessary. Just don´t forget to filter the solution before putting copper in.
Vast surface area of silver cement also help to consume last bits of nitric and eventually the silver all make it to the precipitate - if there is enough copper.


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## Martijn (Feb 18, 2022)

Hartbar said:


> Thanks, is it advantageous to get all the nitric acid used up, by adding more silver with heat as a way to use all the nitric before the next process.
> I see people do that with gold beads in AR


Not needed. Even if you should have all nitric used up, as soon as you add HCL, there is NO3 released from the AgNO3 and turned back into HNO3. 

You could even dissolve more silver with that water if you keep a bit silver nitrate in solution, using up all added chlorides. 
Adding some silver nitrate will use up any overdosed free HCL.


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## Martijn (Feb 18, 2022)

AgNO3 + HCl >> AgCl + HNO3
If my stiochiometry is correct you need 104 ml of 30%HCl to convert one mole of silver, which is 107.8 gr., into one mole of silver chloride. (143.32 gr) 
Creating one mole of nitric acid; 63 gr.


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## Martijn (Feb 18, 2022)

You first need to convert the silver into silver nitrate off course before adding HCL... So for one mole of silver nitrate (169.8 gr) you need 107.8 gr of silver. Just to be clear.

Waste waters reused again and again until the copper gets too concentrated.


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## campbellj46 (Feb 19, 2022)

I usually add more silver to use up excess nitric. Or I boil the solution, add water to bring the volume up, boil again and repeat until all nitric is gone. Adding sulphamic acid really has no benefit and an added expense in the process. Less steps, less expense.


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## Martijn (Feb 19, 2022)

Again, you don't have to. There's no need.


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## FrugalRefiner (Feb 19, 2022)

campbellj46 said:


> I usually add more silver to use up excess nitric. Or I boil the solution, add water to bring the volume up, boil again and repeat until all nitric is gone. Adding sulphamic acid really has no benefit and an added expense in the process. Less steps, less expense.


When you're trying to reduce the volume of a solution, you want to evaporate it, not boil it.

When you boil a solution, you have bubbles that pop when they reach the surface of the solution. When they pop, they send tiny droplets of solution flying out of your container, which will result in the loss of values.

When you evaporate a solution, it is done below the boiling point, so you have no bubbles popping, and no loss of values.

Dave


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## campbellj46 (Feb 19, 2022)

FrugalRefiner said:


> When you're trying to reduce the volume of a solution, you want to evaporate it, not boil it.
> 
> When you boil a solution, you have bubbles that pop when they reach the surface of the solution. When they pop, they send tiny droplets of solution flying out of your container, which will result in the loss of values.
> 
> ...


 Good info to have, thanks. I will keep it under the boiling point and see if that increases my recovery rates. Thank you so much


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## VK3NHL (Feb 19, 2022)

arthur kierski said:


> i did not read your post completelly--- i use ura to denox excess nitric acid from ar----not for silver nitrate extraction,i do not needed


Not a good idea, you do not want to produce Urea Nitrate especially with metal salts in solution.
Urea is best used on the garden.


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