# Nitric acid based cleaning detergents



## refiner123 (Nov 15, 2020)

This forum has loads of threads regarding nitric acid.
None of them seem to cover this question, so I decided to open a new thread.
If the option 4 is discussed in some previous thread, I apologise for opening a new one.

To do some amount of silver refining, I need to get nitric acid. If I process everyhing I have waiting at the moment, I will probably need more than one liter and if I continue with this journey, I will need more.
I have also collected also some amount of ewaste, which I might process at some point. (fingers, pins, etc) Processing of those ewaste pieces will need either HNO3, poor mans AR (NaNO3) or 
sodium hypochlorite (very dilute solution widely available as cleaning product)

Due to EU wide regulation, nitric acid has very limited availability in Finland.
I have found couple of ways to get nitric acid:

1)
The easy and most expensive method.
60% HNO3 for 20eur/l + transport costs (hazardous material transport, will at least double the cost)
HNO3 is available for business purposes without restrictions. (altough this is a hobby, I could use my business id in transactions and I still believe that financially positive results can be achieved if cost of work is free...)
This is from a shop, which sells small amounts of various chemicals to smaller users.
If I order one liter and pay the shipping charges, the next liter will be just as expensive.
5L containers have slightly better unit price and shipping charges would apply only once.
The other options below have lower initial cost than 5l HNO3 container + shipping.


2)
I have seen that some agricultural shops sell 60% HNO3 in 30liter cans for ~50eur + shipping costs.
This is used for example in greenhouses to clean up irrigation pipes and most likely is quite pure.
I am pretty sure that if a new customer orders only HNO3, delivered to clearly a location without any agricultural land nearby, they might inform authorities and there could be lots of questions asked. (even though HNO3 is OK to purchase and store for business use)
And on the other hand, I am not very confident on storing 30liters of HNO3 in plastic container for a long time in my own storage room.
This would be enough HNO3 for lifetime purposes.


3)
Get calcium nitrate fertilizer (15.5-0-0 + 19% Ca, which is 5Ca(NO3)2+NH4NO3+10H2O), 16eur/25kg
and combine it with NaHCO3 30eur/25kg to create NaNO3.
Nitrate fertilisers are listed as possible ingredients of explosives, so the EU wide regulation requires 
shops to report any suspicious buy attempts of nitrate fertilisers. Have to visit some agricultural shop which has calcium nitrate fertiliser in stock and buy with some amount of garden stuff...

There are multiple instructions available to distill HNO3 from NaNO3 + NaHSO4 (widely available as Ph- pool chemical)

If I calculated stoichiometric amounts correctly, 25kg calcium nitrate, 25kg NaHCO3, 35kg NaHSO4.H2O 
would yield with 100% efficiency about 16kg of HNO3, which equals to about 20l of 60% HNO3.
Total comparable cost would be about 8,5 eur/l (60% HNO3). The most expensive ingredient is Ph- chemical.

Ph- and distillation can be skipped for applications where poor mans AR is enough (gold recovery from ewaste), but silver requires HNO3.

This method allows to store relatively safe chemicals and make nitric acid only required amount when needed.
One bag of fertiliser and NaHCO3 each would be enough for lifetime and Ph- can be bought anytime from any store in 1,5 -- 7kg packages.
But there seems to be quite a bit of work to make the nitric acid with this process.


4) I found one professional cleaning detergent, which is based on nitric acid.
This is meant to clean up pipes, tanks and machines of dairy and brewery industries.

This detergent costs 80eur/20l and I found one shop which seems to have pickup location close enough to avoid expensive hazardous transport.
Of course the same EU rules apply as 2) and 3), some questions might be asked if a new customer buys nitric acid based industrial detergent.

Brocuhre tells the contents are:

Organic complexing agents < 5 % Softens water
Non-ionic surfactants < 5 % Removes dirt and lowers surface tension
Nitric acid 24-26 % Removes deposits and prevents the formation of deposits

According to MSDS, this also contains 1-5% citric acid (or is this the same as organic complexing agent mentioned in the brochure)

If it is 25% nitric acid by weight, comparable price for 60% nitric acid would be 11,5 EUR/l if I calculate densities correctly.
Also this option requires storing nitric acid based detergent in plastic container potentially for a long time, which might not be the safest thing to do.


As far as I have understood, 25% nitric acid is strong enough for gold and silver refining.
But the question is, what kind of impurities this kind of detergent can have (non-ionic surfactants...), 
and do they harm while refining gold or silver?

Could those impurities be removed with simple distillation?
Simple distillation without any vigreaux columns, etc would just keep the nitric acid concentration unaffected.
Fractional distillation with vigreaux column could be used to increase the concentration closer to azeotrope, but I have understood that this is a very slow process.


Another agricultural cleaning detergent has 20-40% nitric acid with price 40eur/20l (but delivery costs would be high)
This contains also phosphoric acid 0,1 - 1%, 
N,N-dimethyldecylamine N-oxide 0,1 - 1%
and Dekyylidimetylamine 0,01%

Any idea whether those will effect refining purposes and could those be removed easily with distillation or some other means?


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## refiner123 (Nov 16, 2020)

Hi

I forgot one important question from this:
Would it be any safer to store 20l of 25% nitric acid detergent in plastic container than 30l of 60% nitric acid?
The absolute amount of nitric is smaller, but both quantities are enough for a very long time period.
Will plastic container falll apart during long storage?


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## etack (Nov 19, 2020)

I store my nitric in beer kegs. I use the "pony keg" it 7.5 gal. 28ish liters.

If you can get it, get it and you can always sell the amount you dont use.

Eric


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## refiner123 (Dec 17, 2020)

Agricultural shops don't seem to be willing to sell the cheap 60% nitric to non-farmers 

But I managed to get acidic detergent meant for cleaning milk processing machinery. According to MSDS it is 28% nitric acid. In the endgame this 20 liter canister cost me 53eur including shipping. (which makes the comparable cost of nitric very close to homemade nitric from Calcium nitrate + NaHCO3 + NaHSO4 with hopefully less work)
The next thing is to try distilling it clean enough for silver refining.

It has <1% of phosphoric acid, which should be "easy" to remove by distillation.

I am not sure what kind and how much of surfactants and other contaminants this liquid contains. Hopefully those are the most volatile part of the solution and bubble out first. (or have very high boiling point and stay with the phosphoric acid)

I have found this thread on the other forum covering somewhat similar subject:
http://www.sciencemadness.org/talk/viewthread.php?tid=9499

And somebody has made a youtube video where he distills nitric acid from concrete etching agent:
https://www.youtube.com/watch?v=S6GpMQ98u8I


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## VK3NHL (Feb 20, 2022)

I guess I’m lucky in Australia getting my 73% HNO3 for $A100.0 for 20L.


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## djlotyg (Feb 20, 2022)

VK3NHL said:


> I guess I’m lucky in Australia getting my 73% HNO3 for $A100.0 for 20L.


I’m up for some soon, in Vic. Are you able to tell where that’s from?


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## Dbs (Feb 21, 2022)

VK3NHL said:


> I guess I’m lucky in Australia getting my 73% HNO3 for $A100.0 for 20L.


From Sydney. I'd love to know as well!


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## VK3NHL (Feb 21, 2022)

djlotyg said:


> I’m up for some soon, in Vic. Are you able to tell where that’s from?


I get my HNO3 from PARAMOUNT CHEMICALS In Preston 
Contact: Kal 




__





Contact - Paramount Chemicals


Pick-up is available by appointment only. Call Warehouse 0418 378 999 Address: Rear 160 High St Preston, Victoria 3072, AUSTRALIA Phone No: (03) 94951522 Fax No: (03) 94950112 Email: [email protected]




paramountchemicals.com.au





Kal is great to deal with too..

Regards
Tony


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## VK3NHL (Feb 21, 2022)

VK3NHL said:


> I get my HNO3 from PARAMOUNT CHEMICALS In Preston
> Contact: Kal
> 
> 
> ...


They also stock:
SMB
H2SO4
Sulphamic

Cheers
Tony


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## djlotyg (Feb 22, 2022)

VK3NHL said:


> They also stock:
> SMB
> H2SO4
> Sulphamic
> ...


Much appreciated.


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## Joip11421 (Jun 13, 2022)

Anyone on rhis thread from Nevada, California, Arizona area? In a few months I'm set to start processing my silver scrap that I've collected. Have about 3Kg now, but have found a good source of industrial scrap, just waiting on time. I would prefer not to have to make my own nitric, but if that's my only choice, then I will.


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