# inhibitors in sulfuric



## powermetalx (Apr 11, 2016)

Hi all,
I would like to use sulfuric acid, for making nitric acid (with nitric salt).

But the bottle I got has "inhibitors". Is this a deal-breaker? I have seen some people claim that it is no good when HCl has these added. Are there hazards I should know about? Will the solution be ineffective at dissolving ferrous metals?


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## Topher_osAUrus (Apr 11, 2016)

powermetalx said:


> Hi all,
> I would like to use sulfuric acid, for making nitric acid (with nitric salt).
> 
> But the bottle I got has "inhibitors". Is this a deal-breaker? I have seen some people claim that it is no good when HCl has these added. Are there hazards I should know about? Will the solution be ineffective at dissolving ferrous metals?




I have used that to make my nitric before.

Its pink colored right?

There was some speculation on the forum that it was simply a ph indicator for the factory, others thought it was the inhibitor ingredients.

One thing i noticed, was, after i diluted the acid a bit...and then reconcentrated, it was crystal clear.

The acid i produced with it was decent, but, i have since started using battery acid that i concentrate down.


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## powermetalx (Apr 12, 2016)

Great! Thanks for reply. 

What is the ratio you used for sulfuric to sodium nitrate?


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## upcyclist (Apr 12, 2016)

powermetalx said:


> Great! Thanks for reply.
> 
> What is the ratio you used for sulfuric to sodium nitrate?


You'll find some answers in Lazersteve's Cold Nitric Recipe--please read the whole thread!


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## Topher_osAUrus (Apr 12, 2016)

powermetalx said:


> Great! Thanks for reply.
> 
> What is the ratio you used for sulfuric to sodium nitrate?


Well, that isnt a straight up answer, but i will give it a shot and others can chime in as well

Steves (simple) cold nitric is as follows.
1.bring 100 ml distilled water to boil
2.remove from heat and add 180g of sodium nitrate (slowly, so when it begins to effervesce it doesnt boil over)
(here i filter, but i will type up my methodology next)
3. SLOWLY ADD concentrated sulfuric, DONT ALLOW TO BOIL
4.let chill to room temp (slower to cool the better)
5.AFTER room temp, put it in a salt water/ice bath to -5 degrees C
6.after -5 for 30 minutes, remove (50%ish) nitric from the sulfate salts that formed while chilling.
7.enjoy

I do it very similar, with just a couple things different (im not going to say its better, but, i think this helps)

1. Bring 250 ml di-H2O to boil

2.add 450g NaNO3 prills, dissolve entirely
2b. Filter

3.allow to cool to room temp, then ice bath (dont skip, your vessel will shatter undoubtedly.)
-this will precipitate from the saturated solution fairly pure sodium nitrate crystals (the bag of hi-yield is only 16% nitrates)

4.weigh out the molar equivalent of the saturated solution at 100 degrees C (180g NaNO3-100ml h20)

5. Boil 100 ml di-H2O

6.remove from heat, add purified nitrate

7dissolve, filter again.

8. Add concentrated sulfuric acid (i chill mine in an ice bath, but i run mine through a still)

9.chill to ambient temp, then ice bath to -5

Filter off the salts

Enjoy


Hope this helps


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## Geo (Apr 20, 2016)

Are you trying to distill nitric acid? If you are, sodium nitrate is a poor choice of nitrate. Any other nitrate besides ammonium nitrate will work better with less problems. As an aside, from personal experience, never use calcium nitrate to make poor man's AR. Calcium sulfate is a nightmare to try and deal with.


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## powermetalx (May 9, 2016)

Thanks for that advice! At the present time, all I have is sodium nitrate, so I will use what I have.

Next questions: I know the poor man's AR with just ammonia and muriatic, and I've seen a similar poor man's AR recipe with sodium nitrate and muriatic. Are there downsides to this I should be aware of? Also, is there a way of using the sulfuric acid to strengthen the poor man's AR? I suspect there should be a recipe of sulfuric, sodium nitrate and muriatic that eliminates the step of distilling the nitric, but produces a stronger solution than just sodium nitrate and muriatic.

Let me put my situation and strategy out there, to see what general advice people have:

The long and short of my process so far:
1) I have used an AP method to strip many gold foils from some boards.
2) Unfortunately, a fair amount of gray metastannous precipitate formed--there was solder on there I couldn't get off easily.
3) This slowed down filtering to a crawl, so I had to use several filters. 
4) The resulting filters have a lot of gold in them, but need a little more care processing than a really clean set.

Here is my plan:
1) Make some nitric acid
2) Wash the filters in the nitric, to clean off any residual base metals
3) Put the filters in a poor man's AR solution formed from sodium nitrate and muriatic.
4) Wait for everything to dissolve, including filters, and then separate the (hopefully golden!) AR solution from the crud.
5) neutralize/precipitate, and maybe iterate the process to get higher purity.

Questions:
1) Will the nitric acid dissolve the filters on its own? That is, can I soak the filters in the nitric and expect them to break down totally?
2) Perhaps I can skip the nitric step and just go directly to the AR step?
3) Can I make a stronger AR solution by adding sulfuric, instead of just sodium nitrate and muriatic?

Many thanks!


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## Topher_osAUrus (May 9, 2016)

powermetalx said:


> Thanks for that advice! At the present time, all I have is sodium nitrate, so I will use what I have.
> 
> Next questions: I know the poor man's AR with just ammonia and muriatic, and I've seen a similar poor man's AR recipe with sodium nitrate and muriatic. Are there downsides to this I should be aware of? Also, is there a way of using the sulfuric acid to strengthen the poor man's AR? I suspect there should be a recipe of sulfuric, sodium nitrate and muriatic that eliminates the step of distilling the nitric, but produces a stronger solution than just sodium nitrate and muriatic.
> 
> ...



I havent heard of poor man AR w ammonia and muriatic?.. Ive always read thst ammonia should be best kept from your lab.

Poormans AR is nitrate fertilizer and HCl. I add a little extra water too.
The problems-
-its hard to know exactly how much nitrate to use, so usually its in excess, so i always have to use sulfamic to denox.
-it can create extra salts to deal with

Ive never added sulfuric to my poorman AR, just when trying to evaporate and remove lead sulfate, which i replaced evaporating method of denox to sulfamic.

You say that you had metastannic in your ar?
I thought that was only made when dissolving in nitric? But im not totally for sure.

I do know, that taking your filters straight to nitric is NOT the best bet. You will certainly dissolve gold if you do not follow incineration procedures beforehand.

Honestly, i dont know about the sulfuric in poormans. I always kept to the recipe.

You will surely get more detailed answers shortly.

-topher

Edit to add a key word


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## powermetalx (May 9, 2016)

You're quite right about the poor man's aqua regia not using ammonia. The recipe I saw was for muriatic and bleach. In my defense--it isn't a process I was actually going to use.

Thanks for the reply!


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## UncleBenBen (May 10, 2016)

HCl and bleach will readily dissolve gold foils and powders. Granted, not as fast as AR, but it eliminates the need to denox. Just gently heat the solution after all is dissolved to remove excess chlorine, let it cool, filter well and precipitate.

But as Topher mentioned, do incinerate the filters and foils first. Harold_V's thread on incineration is on the first page of the library section I believe. Follow Harold's advice and you can't go wrong.

Once properly incinerated, the tin can be removed with a good wash in HCl.

What ever route you take, be it poor man's or making nitric or just using bleach, just don't skip incineration. That tin is a thief and will steal your hard won gold from you. Nobody wants that! :mrgreen:


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## upcyclist (May 10, 2016)

powermetalx said:


> You're quite right about the poor man's aqua regia not using ammonia. The recipe I saw was for muriatic and bleach. In my defense--it isn't a process I was actually going to use.


Just a quick correction: "Poor man's AR" is a mixture of HCl (muriatic/hydrochloric acid) and a nitrate (often sodium nitrate). The nitrate ions act as an oxidizer, just like nitric acid in true Aqua Regia.

HCl & Bleach also dissolves gold, because in this case the bleach provides the oxidizing agent. HCl + bleach is NOT, however, "Poor man's AR".


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## powermetalx (May 12, 2016)

Ok. So here is my updated process:
1) Incinerate
2) Wash in HCl 
3) dissolve what remains in poor man's AR or else muriatic-and-bleach.
4) Filter
5) Neutralize and precipate.

I looked at Harold's thread on incineration, and he recommends using a stainless steel pan on very high heat to incinerate. Does anyone else have better suggestions? For one thing, how can I make sure to recover all the valuables from the steel pan? Won't there be many gold flakes and powder clinging to the pan? I prefer to keep all values in a glass/pyrex container so that I can be sure to recover with a simple acid wash.

Thanks again!


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## UncleBenBen (May 12, 2016)

As long as you don't get hot enough to melt, your values won't stick to the stainless steel. I know how you feel. I was nervous as a long tailed cat in a room full of rocking chairs the first few times I incinerated foils.

Just keep it at a dull red glow and don't let it get hot enough to melt and you will be fine. I use a stainless skillet and a cheap propane camp stove and carefully add a bit of heat from above occasionally with a propane torch. It works pretty good for me.

You can also use Corning ware if you don't want to use stainless.


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## Topher_osAUrus (May 12, 2016)

UncleBenBen said:


> As long as you don't get hot enough to melt, your values won't stick to the stainless steel. I know how you feel. I was nervous as a long tailed cat in a room full of rocking chairs the first few times I incinerated foils.
> 
> Just keep it at a dull red glow and don't let it get hot enough to melt and you will be fine. I use a stainless skillet and a cheap propane camp stove and carefully add a bit of heat from above occasionally with a propane torch. It works pretty good for me.
> 
> You can also use Corning ware if you don't want to use stainless.




Yeah! Corning ware for life!

Hah, sorry, i can be pretty dumb...but, i would still like to share!

Both are perfectly acceptable. Both also have their flaws.

Ill start with stainless.
-it only lasts a few incinerations before perforating (thats what scares me...i dont want to lose my precious..)
-once the chromium layer has been compromised, it begins to rust.. Rust begins to flake. Then add iron to your gold. Adding another step of magnetic separation, and minoot(spelling?) loses from that.
-if incinersting stuff that has been in HCl, it attacks the psn quickly... This can be alleviated by neutralizing the chloride salts with sodium hydroxide or the like (which butcher suggests, as gold and other values are easily lost in smoke when in salt compounds)
*-the good-*
-they dont melt
-they dont chip or break
-they are cheap as cheap can be at a second hand store
-other things im overlooking

***Corning Ware***
-*the bad*-
-they are so white and beautiful..who wants to beat them up?(well, i do..at times)
-they can break into a billion.little pieces if they have any flaws
-said flaws, while they may not be noticeable, will still cause problems for you if you are heating and crushing
-i cant think of anything else..but i am biased, as i love corning...that company is the reason for everything...lightbulbs for edison, pyrex, windows in the space shuttle, nose cones for space shuttle, crt tubes, lcd screens, gorilla glass, and about a million other things (i am still going to add to my corningware thread soon, for those that care [*crickets..*]..)

-the good-
-theyre cheap
-resilient
-you can literally melt gold in them -i have done it-
-you can incinerate, leech, and nuke (nitric) in them, with no ill effect..
-and more, but i wont bother you with my fan-boy rant

Ahh...corningware...

What was this thread about again?  

-topher, the obsessive


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## g_axelsson (May 12, 2016)

powermetalx said:


> Ok. So here is my updated process:
> 1) Incinerate
> 2) Wash in HCl
> 3) dissolve what remains in poor man's AR or else muriatic-and-bleach.
> ...


Instead of neutralize, denox!

You want an acidic solution without nitrates, especially if you are using SMB to precipitate.

Göran


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## upcyclist (May 16, 2016)

g_axelsson said:


> powermetalx said:
> 
> 
> > Ok. So here is my updated process:
> ...


Indeed! Note that the final stage of the waste treatment process starts with neutralizing the waste acid in order to drop _all remaining metals_ (or at least as many of them as possible). Not just the gold.


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## nickton (Feb 4, 2018)

iopu :mrgreen:


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