# Sulfamic acid



## Zhazham (Apr 7, 2022)

I have been trying to find sulfamic acid to neutralise excess nitric in AR solution. Does it need to be pure sulfamic acid? There are many products containing 30-50% of it but i can't find 100% stuff.

I found possibly interesting product with sulfamic acid, SMB and a bit of tencides. It is used in farms, to wash milk tanks. Wondering, if it would be ready mixture to drop off gold from AR solution?


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## orvi (Apr 7, 2022)

It is often used for cleaning coffee machines or descaling the lime sediment from tubes and closed appliances. Solid crystalline powder that is practically pure sulfamic acid.


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## Zhazham (Apr 7, 2022)

Thank's for the tip. I found some products for cleaning up coffee machines but those also contain citric acid. Just have to keep on looking..


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## PeterM (Apr 8, 2022)

Sulfamic acid is cheap, here on Ebay Sulfamic Acid 1 lb Bag 99.8% Technical Crystal | eBay


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## richoc (Apr 8, 2022)

In Finland I have no idea where you would go, but here you can get Sulfamic at a home beer brewing supply store. Used as a bottle wash solution, not sure if it is pure.

There are many other ways to deal with the excess nitric, mine is to add more Gold to put it to use.
You can add in a Gold button on known weight just use up the acid if nothing else on hand.

Urea that can be obtained at any fertilizer store, 50 lbs last year was $12 USD at the big farm supply place.
The Urea will turn the Nitric acid back to Sulfuric acid, there by dropping and lead so you need to filter.
Go very easy on the use of the Urea because it will cause a build up if to much is used.
To get out any Lead dropped before dropping the Gold, saves a step of dropping some Sulfuric to drop the lead.

You can simmer it off, reduce the amount of solution by cooking it down, forcing out the Nitric as gas.
Then cool add 3x the volume of distilled water and then SMB to drop your Gold.
You really only need a Milligram more of SMB than the expected Gold recovery, to many people waste a lot of supplies.


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## FrugalRefiner (Apr 8, 2022)

richoc said:


> Urea that can be obtained at any fertilizer store, 50 lbs last year was $12 USD at the big farm supply place.
> The Urea will turn the Nitric acid back to Sulfuric acid, there by dropping and lead so you need to filter.
> Go very easy on the use of the Urea because it will cause a build up if to much is used.
> To get out any Lead dropped before dropping the Gold, saves a step of dropping some Sulfuric to drop the lead.


Urea will not create sulfuric acid. That's a benefit of using sulfamic acid. Urea ( CO(NH2)2 ) lacks any sulfur, which sulfamic acid ( H3NSO3 ) provides.



richoc said:


> You can simmer it off, reduce the amount of solution by cooking it down, forcing out the Nitric as gas.
> Then cool add 3x the volume of distilled water and then SMB to drop your Gold.
> You really only need a Milligram more of SMB than the expected Gold recovery, to many people waste a lot of supplies.


When evaporating to eliminate excess nitric, you should add HCl once the solution is highly concentrated. It will evolve NOx gas from nitrates trapped in the solution. Repeat if needed till no more NOx evolves.

After diluting the solution, do a final filtration to eliminate any silver chloride that might precipitate from the dilution.

Dave


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## richoc (Apr 13, 2022)

Never tried hitting it with HCL after a "final concentration" all other metals "removed" in the process before this step , the final drop.
Then 3 washes of the gold cake with Lab grade HCL then 3 rinses with near boiling water seams to make sure the gold is clean to melt.

I have not used the method of "cooking it down" in a long time (just a few time ever but that was how I was trained to process) as my developed method now is to work slow and cold to avoid off gassing NOx. I am in a large city and try to avoid drawing any unwanted attention to what I am doing, orange smoke coming out of the fume pipe would do this. I try and condense all the escaping gasses and use them back in the reaction until expended. When I open my reaction chamber to the open air, I hope to see no colored vapors escaping it at all.

I have always wondered about this nasty smell people speak off when doing a SMB drop?
I have never experienced a "nasty smell " during the addition of SMB.
Is that "nasty smell" do to the excess Nitric still present?


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## Yggdrasil (Apr 13, 2022)

richoc said:


> Never tried hitting it with HCL after a "final concentration" all other metals "removed" in the process before this step , the final drop.
> Then 3 washes of the gold cake with Lab grade HCL then 3 rinses with near boiling water seams to make sure the gold is clean to melt.
> 
> I have not used the method of "cooking it down" in a long time (just a few time ever but that was how I was trained to process) as my developed method now is to work slow and cold to avoid off gassing NOx. I am in a large city and try to avoid drawing any unwanted attention to what I am doing, orange smoke coming out of the fume pipe would do this. I try and condense all the escaping gasses and use them back in the reaction until expended. When I open my reaction chamber to the open air, I hope to see no colored vapors escaping it at all.
> ...


Its the So2 gas, it stings in the nostrils and if inhaled will combine with water to create precursors to Sulfuric.
Some find it unbearable, to me it's just mildly irritating so I just pull back and continue.
Of course if breathing with your nose it will never reach high concentrations, because you will have to leave the area before it becomes dangerous.


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## orvi (Apr 13, 2022)

Yggdrasil said:


> Its the So2 gas, it stings in the nostrils and if inhaled will combine with water to create precursors to Sulfuric.
> Some find it unbearable, to me it's just mildly irritating so I just pull back and continue.
> Of course if breathing with your nose it will never reach high concentrations, because you will have to leave the area before it becomes dangerous.


SO2 is very good preservative  old sayings about guys that worked in pyrite-roasting facilities (old manufacture of sulfuric acid via FeS2 -> SO2 -> SO3 -> H2SO4) were they never catched flu or tonsillitis  However, their wives pointed out that their bed performance gradually decayed  so be careful with SO2. Also people with blood pressure issues or heart diseases/difficulties should be on higher alert, because SO2 could mess up the heart rhytm and blood pressure.


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## Zhazham (Apr 14, 2022)

Thanks's for all these tips. Helped me to look to right direction. I found product of +99% sulfamic acid. It is for cleaning up room humidifier. It is widely available in supermarkets.

Nowdays it is a bit difficult to find anything by googling. Google is lifting up not so relevant results, because of their business model.


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## Zhazham (Apr 14, 2022)

About Urea. I have seen many advices to not to use It with nitric acid. From one source i heard that it would make explosive Urea nitrate. I don't have such expertise to know if it is true, but sounds plausible to me.


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## Edlin (May 10, 2022)

Zhazham said:


> I have been trying to find sulfamic acid to neutralise excess nitric in AR solution. Does it need to be pure sulfamic acid? There are many products containing 30-50% of it but i can't find 100% stuff.
> 
> I found possibly interesting product with sulfamic acid, SMB and a bit of tencides. It is used in farms, to wash milk tanks. Wondering, if it would be ready mixture to drop off gold from AR solution?


Check the tile section. It’s also used to clean grout from tile.


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## dpgold (Aug 17, 2022)

FrugalRefiner said:


> Urea will not create sulfuric acid. That's a benefit of using sulfamic acid. Urea ( CO(NH2)2 ) lacks any sulfur, which sulfamic acid ( H3NSO3 ) provides.
> 
> 
> When evaporating to eliminate excess nitric, you should add HCl once the solution is highly concentrated. It will evolve NOx gas from nitrates trapped in the solution. Repeat if needed till no more NOx evolves.
> ...


So when sulfamic acid reacting with HCL will produce sulfuric acid will precipitate any lead present? The lead then needs to be filtered and then drop the gold? In the case denoxing is done with urea and a bit of sulfuric added that will also drop lead?


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## 4metals (Aug 17, 2022)

Why use urea and sulfamic? If you are using urea and you suspect lead, add a small amount of sulfuric acid to drop the lead.


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## dpgold (Aug 17, 2022)

4metals said:


> Why use urea and sulfamic? If you are using urea and you suspect lead, add a small amount of sulfuric acid to drop the lead.


thank you, that is what I wanted to know.


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## Yggdrasil (Aug 17, 2022)

dpgold said:


> So when sulfamic acid reacting with HCL will produce sulfuric acid will precipitate any lead present? The lead then needs to be filtered and then drop the gold? In the case denoxing is done with urea and a bit of sulfuric added that will also drop lead?


No, not the HCl, but the Nitric and the NOx will. And this way destroy any surplus Nitric and NOx, giving you some Sulfuric as end result.


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## ZPM (Oct 30, 2022)

A few years ago I read that prolonged exposure to SO2 can cause your body to build up a tolerance to its odor. This is not a good tolerance. You can potentially be exposed to higher levels of SO2 gas while your nose is telling you it's "not so bad".
Please use proper PPE and/or a fume hood. Your health is far more valuable than any precious metal.


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## Ray Levi (Dec 12, 2022)

Zhazham said:


> I have been trying to find sulfamic acid to neutralise excess nitric in AR solution. Does it need to be pure sulfamic acid? There are many products containing 30-50% of it but i can't find 100% stuff.
> 
> I found possibly interesting product with sulfamic acid, SMB and a bit of tencides. It is used in farms, to wash milk tanks. Wondering, if it would be ready mixture to drop off gold from AR solution?


Contact www.xelexo.net. great prices, free shipping.


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