Nitric acid recovery from sodium nitrate waste solution with excessive sodium chloride (salt)?

[icejj]

Is it possible to recover nitric acid after silver chloride precipitation using too much NaCl sodium chloride (salt)?

I had a copper nitrate waste solution which was a result of performing the 50/50 method of nitric and distilled water on gold filled material. I then added sodium chloride NaCl (salt) to the waste solution to precipate the silver out of the waste solution as silver chloride. I ended up using too much salt, so I now essentially have aqua regia. I know this because I tested the resulting solution and it dissolved gold. Is there a way to recover the nitric acid from this solution now that the solution is essentially a weaker form of aqua regia due to adding too much salt?

 

[Yggdrasil]

Is it possible to recover nitric acid after silver chloride precipitation using too much NaCl sodium chloride (salt)?

I had a copper nitrate waste solution which was a result of performing the 50/50 method of nitric and distilled water on gold filled material. I then added sodium chloride NaCl (salt) to the waste solution to precipate the silver out of the waste solution as silver chloride. I ended up using too much salt, so I now essentially have aqua regia. I know this because I tested the resulting solution and it dissolved gold. Is there a way to recover the nitric acid from this solution now that the solution is essentially a weaker form of aqua regia due to adding too much salt?

Not much to do with that other than spend the Chlorides by dissolving more Gold.
Or set it aside for your next AR batch, some extra Salt will not affect that much.

 

[icejj]

Not much to do with that other than spend the Chlorides by dissolving more Gold.
Or set it aside for your next AR batch, some extra Salt will not affect that much.

Could I use the solution on gold-filled material until the chlorides are used up? I'm thinking that if I were to use the solution to get rid of the base metals for a large batch of gold filled material, then correct if I'm wrong, but wouldn't the solution dissolve the gold and other metals until there are no more chlorides present, then cement the gold out of solution due to the presence of a large amount of base metals still being digested (and maybe even create silver chloride in the process), and then the rest of nitric in solution would continue dissolving the rest of the base metals of the gold filled material? And thus I would end up with no more chlorides, precipitated gold, gold "shells" from the gold filled material, and precipitated silver chloride?

I'm trying to see if I can find a way to still reuse the solution on gold-filled material, since I have a lot of this solution left over and don't want to let the nitric go to waste if I don't have to...

 

[Yggdrasil]

Could I use the solution on gold-filled material until the chlorides are used up? I'm thinking that if I were to use the solution to get rid of the base metals for a large batch of gold filled material, then correct if I'm wrong, but wouldn't the solution dissolve the gold and other metals until there are no more chlorides present, then cement the gold out of solution due to the presence of a large amount of base metals still being digested (and maybe even create silver chloride in the process), and then the rest of nitric in solution would continue dissolving the rest of the base metals of the gold filled material? And thus I would end up with no more chlorides, precipitated gold, gold "shells" from the gold filled material, and precipitated silver chloride?

I'm trying to see if I can find a way to still reuse the solution on gold-filled material, since I have a lot of this solution left over and don't want to let the nitric go to waste if I don't have to...

Yes there will simultaneous dissolving and cementing including formation of Silver Chloride.
Not very recommended, can be messy.

One can use it for Dissolving Gold or producing Silver Chloride.
If you have some amounts of dissolved Silver, you can use this to drop the Silver as Silver Chloride and when the Chlorides are spent you will have a solution of Nitric and basically Sodium Nitrate which should be safe for Silver or AR.

 

[Martijn]

Could I use the solution on gold-filled material until the chlorides are used up? I'm thinking that if I were to use the solution to get rid of the base metals for a large batch of gold filled material, then correct if I'm wrong, but wouldn't the solution dissolve the gold and other metals until there are no more chlorides present, then cement the gold out of solution due to the presence of a large amount of base metals still being digested (and maybe even create silver chloride in the process), and then the rest of nitric in solution would continue dissolving the rest of the base metals of the gold filled material? And thus I would end up with no more chlorides, precipitated gold, gold "shells" from the gold filled material, and precipitated silver chloride?

I'm trying to see if I can find a way to still reuse the solution on gold-filled material, since I have a lot of this solution left over and don't want to let the nitric go to waste if I don't have to...

I think adding silver nitrate is the best option to get all chlorides out.

 

[orvi]

Is it possible to recover nitric acid after silver chloride precipitation using too much NaCl sodium chloride (salt)?

I had a copper nitrate waste solution which was a result of performing the 50/50 method of nitric and distilled water on gold filled material. I then added sodium chloride NaCl (salt) to the waste solution to precipate the silver out of the waste solution as silver chloride. I ended up using too much salt, so I now essentially have aqua regia. I know this because I tested the resulting solution and it dissolved gold. Is there a way to recover the nitric acid from this solution now that the solution is essentially a weaker form of aqua regia due to adding too much salt?

In small ammounts, there is no gain in recovering nitric, if you factor in the time spent and energies.

For the future, I would advise to cement the silver on copper and then move to the recovery of nitric, if you determined to do it. AgCl is just another obstacle in the path, cementation is producing already metallic silver, just stir it well and give it plenty of time to properly cement.

As it was mentioned, sad news. When you overadd chlorides, they will stay in the pot. Only application is to use this nitrate rich feed as oxidizer in AR-like dissolutions. We did this quite a bit in the past, when we concentrated copper nitrate waste from silver refining and dumped it into the AR dissolution of general gold plated scrap, instead of nitric acid. To start the dissolution, then we continued with regular nitric to finish the dissolution of course.

 

[Martijn]

In small ammounts, there is no gain in recovering nitric, if you factor in the time spent and energies.

For the hobbyist, reusing the copper nitrate and converting it to nitric by adding sulfuric makes a great first leach for copper cell anode slimes or gold slimes from the sulfuric stripping cell.

Especially if you can't buy it anymore. And lab distillation sets are hard to buy in your country or ridiculously expensive.

Poor mans nitric is still an option.

These workarounds are time consuming though.

 

[Martijn]

Slow reactions with lots of reflux. Save on use and you'll have less to recover.

 

[icejj]

For the future, I would advise to cement the silver on copper and then move to the recovery of nitric, if you determined to do it.

I learned that the hard way. I have about 20 gallons of waste that I precipitated silver chloride out of that has too much salt in it. Once I realized that cementing with copper would be ideal for me instead, I switched to doing it that way and now have about 15 gallons of copper nitrate, that I'm in the process of recovering the nitric from by adding sulfuric acid.

As it was mentioned, sad news. When you overadd chlorides, they will stay in the pot. Only application is to use this nitrate rich feed as oxidizer in AR-like dissolutions.

So even if I added silver nitrate to the aforementioned 20 gallons to create silver chloride and spend the chlorides, I still wouldn't be able to recover just the nitric by adding sulfuric acid to the solution due to the presence of the chlorides? Correct? I think I see now. Thanks!

 

[orvi]

So even if I added silver nitrate to the aforementioned 20 gallons to create silver chloride and spend the chlorides, I still wouldn't be able to recover just the nitric by adding sulfuric acid to the solution due to the presence of the chlorides? Correct? I think I see now. Thanks!

No, you can. But it depends on how much chlorides do you have in. If it is just a little, you can pour in some reasonable excess of silver solution until you see formation of white precipitate. Essentially, you can "titrate" this solution with silver solution. As AgCl is very insoluble, hardly any chlorides would be left in the liquid - and that enables you to continue with the nitric recovery.

Every 107g of dissolved silver require around 58 g of NaCl to be precipitated from solution as silver chloride. I assume you used saturated brine for precipitation... That said, with solubility of salt being 33g/100ml, you would need to add roughly 110 g of dissolved silver in nitrate solution to scavenge excess chlorides from roughly 190 ml of saturated brine. That is just a quick ballpark calculation, but should give you the idea where you are and what need to be done to reach the goal

 

[orvi]

For the hobbyist, reusing the copper nitrate and converting it to nitric by adding sulfuric makes a great first leach for copper cell anode slimes or gold slimes from the sulfuric stripping cell.

Especially if you can't buy it anymore. And lab distillation sets are hard to buy in your country or ridiculously expensive.

Poor mans nitric is still an option.

These workarounds are time consuming though.

Yeah, I understand this. I also struggled to buy the nitric from the start, however, nowdays, when you cannot even buy sulfuric acid... It is tough to even go with Poorman´s...

Usable nitric can be made from calcium nitrate fertilizer by addition of sulfuric acid tho. Not the most plesant operation to do, but OK. I distilled some nitric in the past, but recovery is tedious to be honest.

 

[icejj]

No, you can. But it depends on how much chlorides do you have in. If it is just a little, you can pour in some reasonable excess of silver solution until you see formation of white precipitate. Essentially, you can "titrate" this solution with silver solution. As AgCl is very insoluble, hardly any chlorides would be left in the liquid - and that enables you to continue with the nitric recovery.

Oh okay. I'm going to try it this way then. I don't know if it's a small amount though...

Every 107g of dissolved silver require around 58 g of NaCl to be precipitated from solution as silver chloride. I assume you used saturated brine for precipitation... That said, with solubility of salt being 33g/100ml, you would need to add roughly 110 g of dissolved silver in nitrate solution to scavenge excess chlorides from roughly 190 ml of saturated brine. That is just a quick ballpark calculation, but should give you the idea where you are and what need to be done to reach the goal

This was very helpful . Thanks!

 

[icejj]

Yes there will simultaneous dissolving and cementing including formation of Silver Chloride.
Not very recommended, can be messy.

One can use it for Dissolving Gold or producing Silver Chloride.
If you have some amounts of dissolved Silver, you can use this to drop the Silver as Silver Chloride and when the Chlorides are spent you will have a solution of Nitric and basically Sodium Nitrate which should be safe for Silver or AR.

Thanks for this!

 

[icejj]

For the hobbyist, reusing the copper nitrate and converting it to nitric by adding sulfuric makes a great first leach for copper cell anode slimes or gold slimes from the sulfuric stripping cell.

I added a calculated amount of sulfuric to copper nitrate waste (for this batch of copper nitrate waste, I precipitated the silver out of solution using copper), and although it produced a lot of copper sulfate, the color of the resulting solution is still blueish. The blueish color is a lot lighter in tint than before I added the sulfuric, but it is still tinted blue. I expected it to be colorless or close to it? I burned a few drops of the resulting solution and it turned white instead of black, so the amount of sulfuric seems to be fine. Any reasons why my solution still has dissolved metals in it? I feared that I would saturate the solution with too much sulfuric if I were to keep adding more without consulting someone... any idea on what I should do next?

 

[Yggdrasil]

I added a calculated amount of sulfuric to copper nitrate waste (for this batch of copper nitrate waste, I precipitated the silver out of solution using copper), and although it produced a lot of copper sulfate, the color of the resulting solution is still blueish. The blueish color is a lot lighter in tint than before I added the sulfuric, but it is still tinted blue. I expected it to be colorless or close to it? I burned a few drops of the resulting solution and it turned white instead of black, so the amount of sulfuric seems to be fine. Any reasons why my solution still has dissolved metals in it? I feared that I would saturate the solution with too much sulfuric if I were to keep adding more without consulting someone... any idea on what I should do next?

There is still Copper in it.

 

[eaglekeeper]

Yeah, I understand this. I also struggled to buy the nitric from the start, however, nowdays, when you cannot even buy sulfuric acid... It is tough to even go with Poorman´s...

Nurdrage on YouTube has a video on how to make nitric acid from Sodium Bisulfate and a nitrate salt. It will still require a distillation.

I've never had the need to try it........yet.

 

[icejj]

There is still Copper in it.

So I should continue adding sulfuric, even though the solution is burning white when I add a few drops to a small beaker and apply heat?

 

[Martijn]

I added a calculated amount of sulfuric to copper nitrate waste (for this batch of copper nitrate waste, I precipitated the silver out of solution using copper), and although it produced a lot of copper sulfate, the color of the resulting solution is still blueish. The blueish color is a lot lighter in tint than before I added the sulfuric, but it is still tinted blue. I expected it to be colorless or close to it? I burned a few drops of the resulting solution and it turned white instead of black, so the amount of sulfuric seems to be fine. Any reasons why my solution still has dissolved metals in it? I feared that I would saturate the solution with too much sulfuric if I were to keep adding more without consulting someone... any idea on what I should do next?

The copper nitrate(greenish blue) will be converted to copper sulfate(cobalt blue) and some free nitric.
To get most of the copper sulfate out, put it in a freezer and decant the liquid from the blue crystals.
To see if all copper nitrate is converted, dry a drop of the solution in a beaker. White is anhydrous CuSO4, indicating a slight excess of sulfuric. Green means there is still CuNO3 in there. Add a bit more sulfuric if you want to get it out, but honestly you will probably create more copper nitrate with that recovered nitric, so dont worry about it.

To get colorless nitric, you will need to distill the nitric out.
There will always be traces of copper sulfate, regardless of how wel you concentrate it and then how deep you freeze it.
So blue it will be.

 

[icejj]

The copper nitrate(greenish blue) will be converted to copper sulfate(cobalt blue) and some free nitric.
To get most of the copper sulfate out, put it in a freezer and decant the liquid from the blue crystals.
To see if all copper nitrate is converted, dry a drop of the solution in a beaker. White is anhydrous CuSO4, indicating a slight excess of sulfuric. Green means there is still CuNO3 in there. Add a bit more sulfuric if you want to get it out, but honestly you will probably create more copper nitrate with that recovered nitric, so dont worry about it.

To get colorless nitric, you will need to distill the nitric out.
There will always be traces of copper sulfate, regardless of how wel you concentrate it and then how deep you freeze it.
So blue it will be.

Okay I see, thank you for the clarification.

 

[Martijn]

Okay I see, thank you for the clarification.

Next time you don't need to calculate, just take 100ml of the solution and add sulfuric, slowly and keep track of how much you added until a test drop turns white.
Multiply it by 10 times the total amount of liters of solution to convert and add a bit less at once. Then add small bits until the test drop turns white again.