Recovering water and nitric acid from copper nitrate?

[SerialHobbiest]

I found this interesting video on recovering nitric acid and water from copper nitrate https://youtu.be/hmB5x0LYfSE

Does anyone do this for their gold and silver waste?

I’m not anywhere near doing something like this, since I haven’t even CREATED any waste copper nitrate yet, but it seems fairly easy and environmentally safer when done correctly. The set up looks a lot like the two chamber fume scrubber I’ve seen pics of in this forum.

If I ever get to the point of refining in any volume, I like the idea of doing it in such a way that limits waste and recoups valuable ingredients. Are there other ways to material out of the refining waste stream and putting it back into the process?

 

[butcher]

Copper nitrate can be a very useful waste byproduct, I have recovered nitric from copper nitrate (using similar but different processes in the video), but also used it in other recovery processes or to make other reagents from what many may consider a waste.

There are many different ways to reuse much of the waste byproducts we generate before it is treated and disposed of.
Sulfuric acid is basically a waste byproduct of the industries (much of this waste comes from just trying to keep our air clean from other chemical processes mostly from the mining industry). The industries found it cost them a lot of money to safely dispose of this acid, So in order to save money, they started finding as many different uses they could for the sulfuric waste or ways to market their trash, so guess who invented some of our drain products and came up with many of the other products or uses of the sulfuric in order to sell this waste produced, instead of paying to dispose of it.

 

[Geo]

Slowly evaporate the copper nitrate with minimum heat, if any. It's better to cover loosely with a cloth or paper towel and allow it to evaporate on it's own. Keep it in a cool, dry place. Once it evaporated as far as it will within a reasonable amount of time, place the copper nitrate in a distillation rig. Measure an amount of concentrated sulfuric acid that is 10% of your copper nitrate. Slowly add the acid to the flask. Go slow to prevent spitting and sputtering. Slowly heat the flask to 210°F to start the reaction. The reaction is complete when the material in the boiling flask is relatively dry. The remaining salt will be copper sulfate. The nitric acid will distill off. Any excess water in solution will distill over first so test the first of the distillate until it reacts to copper when dripped on it.

 

[SerialHobbiest]

Quick follow up question: I’m planning to use the silver chloride, lye and sugar path to get my metallic silver. Will I be able to recover nitric acid after precipitating the silver chloride out of the silver nitrate? In other words, will the salt I use to covert to silver chloride make it impossible to recover the nitric?

 

[butcher]

Depends.

Say you have AgNO3 silver nitrate, note the name nitrate, not nitric so we have basically no nitric or acid, but a salt of silver and a salt of nitrate ions.

So if I add salt to this salt of silver (note here no acid, no hydrogen or hydronium ions?
silver nitrate reaction with sodium chloride producing an insoluble silver chloride in a solution of sodim nitrate.
AgNO3 + NaCl --> AgCl + NaNO3

Or using potassium chloride salt to produce insoluble silver chloride in a solution of potassium nitrate.
AgNO3 + KCl --> AgCl + KNO3

but we can add the hydronium ions from say sulfuric acid and make an solution of nitric acid in a salt solution of potassium sulfate or sodium sulfate.

2NaNO3 + H2SO4 --> 2HNO3 + Na2SO4
2KNO3 + H2SO4 --> 2HNO3 + K2SO4
freezing the solution we can remove some of the salts and use as poor mans nitric acid.
Better yet distill off the nitric acid from the sulfate salts.

Now if we used acid to make our silver chloride.
AgNO3 + HCl --> AgCl + HNO3
Here we have an insoluble silver chloride in a solution of nitric acid.
Here the hydronium ion from our acid gives us nitric acid,
But here also comes our problem, if we add an excess of HCl we actually make a form of aqua regia which the silver chloride is still insoluble in, this acid begins decomposition upon mixing, and this acid or product is no longer nitric acid...

AgCl + HNO3 + HCl --> silver chloride in aqua regia.

Cementing the silver out of the nitrate solution using copper gives you silver metal (without the hassle or problems of conversion of the silver salts back to metal.

Then the copper nitrate can be made into nitric acid, by adding copper, and H2SO4 and then distilling.

If the added copper was gold plated then you may wish to see my post on killing more than one bird with a stone, to recover the gold while making nitric acid, and leaving you with copper sulfate byproduct to use in electrolysis recovery projects...

 

[SerialHobbiest]

Thank you, Butcher. I can’t afford a silver cell or the forge needed to make shot, etc., and I don’t feel I’d be able to ethically run a cell in my home anyway. My best bet at getting fine silver at the end is the lye and sugar process.

I have some experience to earn before I start thinking about recouping nitric anyway, so I’ll table that for the time being.

 

[butcher]

Can’t afford a silver cell , the forge needed to make shot, etc.,

Cementing the silver on copper, leaving you with copper nitrate solution (which can be reused later for other purposes), leaving you with a fairly pure silver, without the hassle of dealing with the chloride conversion of the silver.
I hate converting silver chloride and avoid making it whenever possible.
I have had better luck using the dilute sulfuric and iron method to convert silver chloride to metal, than ever using the sugar/lye method, or trying to reduce it with a soda ash and carbon fusion and flux melting it...

The more you study and learn the more you may find you do not need to spend a lot on equipment, there are many ways to improvise, and many times those ways can actually be or work better than spending a bunch of money on equipment you find out later you really do not need.
You can always make a simple silver cell (that is if you have enough silver and the need.
You can start out with a Mapp gas torch and a $3.00 melting dish.
Invest in education and it will pay for the lab supplies.

Lou made some good posts on getting silver pure with the silver chloride conversion methods, looking up those should prove helpful in your adventure.

Keep us posted of how the project proceeds, with either way you choose to go.

 

[SerialHobbiest]

Will do. I haven’t heard of the sulfuric and iron method, I’m going to look into it.

 

[SerialHobbiest]

Butcher, if you don’t mind me asking, what difficulties did you have with the lye and sugar conversion?

 

[butcher]

It is silver chloride itself I dislike to have to convert. So I do not make silver chloride if I do not have to.
Cementing silver from a nitrate solution using copper helped to solve that problem for the most part.

I had several problems, probably the same as most others have had, of things not working like the book said they would, or be as easy as it sounded like it should be.
One problem with trying to convert a very large batch of silver, left me with a wood work bench covered in gray purple silver, (broken glassware).
silver chloride conversion with the Karo syrup and lye method works, stirring can be a problem (household blender helped), if the silver chloride is not fresh and clean it becomes more difficult, you need the lye to convert the silver to oxide or hydroxide (turn black) in the process, although the process would generate heat, sometimes it did not seem to generate enough on its own and I would have to add heat, basically my results about half the time failed.
Basically I just found it easier to use the sulfuric and iron method when I did have silver chloride to convert to metal, I found it easier for me and that I have less trouble getting the conversion to move forward, so by choice I did not practice my skills using the lye method any further, I found what worked for me.