Diluted Nitric Acid Recovery

[jimbo12]

Is there a Specific Sequence to Follow if I want to Recover my Silver Metal, Plat. ,Copper,and is it possible to recover the Nitric ?
Acid was 70% and was Reduced by Distilled Water at approx. Ratio 1 gal. acid to 5 gal. water ? There is approx 8 oz. of Inquarted that is in solution
Thank You

 

[Yggdrasil]

Is there a Specific Sequence to Follow if I want to Recover my Silver Metal, Plat. ,Copper,and is it possible to recover the Nitric ?
Acid was 70% and was Reduced by Distilled Water at approx. Ratio 1 gal. acid to 5 gal. water ? There is approx 8 oz. of Inquarted that is in solution
Thank You

Since the information is a bit low, I'm just guessing here.
You used the acid to part inquarted Gold?
And you have not done anything to it after?

 

[jimbo12]

Since the information is a bit low, I'm just guessing here.
You used the acid to part inquarted Gold?
And you have not done anything to it after?

Yes I have not gone to aqua yet

 

[Martijn]

This is a good video for you.

I just evaporated 9 liter of copper nitrate waste solution down to 600ml of mainly copper nitrate trihydrate. Did that at 60 degrees C to avoid decomposition and loose nitric. He only evaporated down until the color shifted to green.
Bottled it for when I have a good distillation setup ready.
You can save the copper sulfate to make electrolyte for a future copper refining cell.

 

[Yggdrasil]

Yes I have not gone to aqua yet

If you add HCl little by little you will drop the Silver to Silver Chloride and thus regenerate some of the Nitric.
Then you can go different ways, search the forum.

 

[Martijn]

If you add HCl little by little you will drop the Silver to Silver Chloride and thus regenerate some of the Nitric.
Then you can go different ways, search the forum.

Ok. I read it wrong. He dissolved 8 oz of inquarted gold in a gallon of 70% nitric and 5 gallon of water.
So 6 oz of silver was dissolved and that leaves enough free nitric for another 100 oz to be dissolved or 3 kilo of silver.

It will be a long slow process fractionally distilling that back down to the azeotrope of 68%

Then carefully converting most of the silver to chlorides should work better.
You can calculate stoichiometrically how much you need for 6 oz and leave a little silver in solution to ensure no chlorides are left and use that for future inquarting or sterling recovery.
If you need some nitric for AR, you take some and add more HCl and filter it clean of AgCl.

You have enough free nitric in there to dissolve another couple of kilo's of silver.
For next attempts, add one ml of 68% HNO3 for one gram of silver or 31 ml for one ounce. It's actually about 1.25ml per gram but better be safe than sorry.
In your case that's six time as much as your is diluted.
Slowly add small amounts until all is dissolved or leave a small amount undissolved.
Adding copper at this point to cement the silver out would consume and waste the nitric and take about a kilo of copper.

 

[lazersteve]

Some of the Nitrate goes up in smoke as NOx when dissolving so the above suggestion do work but with a net loss of nitric thru each pass. I typically get 3 decent cycles of nitric when dissolving silver before I perform a full nitrate recovery on the remaining nitric in the solution.

Equation for dissolving Ag in diluted nitric acid is:

3Ag + 4HNO3 → 3AgNO3 + NO + 2H2O

So you lose one NO3-, or 25% of your nitric with each pass. (75% left after 1 pass, 56.3% after second pass, and 42% after 3rd pass). Put in simple terms if you start with an equivalent 1000ml of concentrated (15.9 moles) HNO3 you will have roughly 750ml (~12 moles) recoverable after 1 pass, 563ml (~9 moles) after 2 passes, and 420ml (~6.7 moles) recoverable after the third pass. For these figures I multiplied the starting molarity by the 0.75, 0.563, and 0.42 for illustration. I didn't run the numbers for each pass so these estimates are likely a little high after the first run, but you get the idea. It's the law of diminishing returns, but it works, I've tested it repeatedly in my work.

Steve

 

[jimbo12]

So maybe I should have explained this better ......

51 oz. went into nitric solution

21 oz. gold
20 oz. copper
13 oz. silver

Approx 5 Gals. Distilled Water and 1 Gal. 70% Nitric

My Objective Here Is To Find Out What Sequence (In What Order ) to Pull My Silver / Other Precious Metals back out and Since Nitric is More Expensive am I better off Rejuvenating the Nitric and than Neutralize Leftovers

 

[lazersteve]

Solution gets filtered off of solids rinsing with distilled water.

Silver gets precipitated as chloride.

Siphon solution from silver chloride.

Rinse silver chloride repeatedly until wash waters are clear.

Test a few ml of solution by first adding sulfamic acid to kill any nitric/nitrates followed by stannous test.

Steve

 

[Yggdrasil]

So maybe I should have explained this better ......

51 oz. went into nitric solution

21 oz. gold
20 oz. copper
13 oz. silver

Approx 5 Gals. Distilled Water and 1 Gal. 70% Nitric

My Objective Here Is To Find Out What Sequence (In What Order ) to Pull My Silver / Other Precious Metals back out and Since Nitric is More Expensive am I better off Rejuvenating the Nitric and than Neutralize Leftovers

Simply put.
Gold will be in solid form.
Siphon all the liquid into another container.
HCl will convert the Silver Nitrate to Silver Chloride and regenerate most of the Nitric and add a small amount of water.

Take a small amount for example 10ml and measure how much HCl is needed before it stops forming a white cloud.
Calculate how much HCl is needed for the whole solution. And add a little less to your solution, then start adding in small increments.
You can switch to table salt in the end to avoid creating Aqua Regia.
Let it settle and siphon off the liquid. This is now mainly a solution of Copper Nitrate.
The Solid needs proper washing and rinsing, keep the washes in a container of its own or mix it with the other if you have he time to evaporate.
Now you have clean Silver Chloride to process, there are two common methods for that, Lye-Sugar method or Iron-dilute Sulfuric method.
The rest of the solution is well explained by Lazersteve and others.
It might be wise to evaporate it a bit though.

 

[jimbo12]

Simply put.
Gold will be in solid form.
Siphon all the liquid into another container.
HCl will convert the Silver Nitrate to Silver Chloride and regenerate most of the Nitric and add a small amount of water.

Take a small amount for example 10ml and measure how much HCl is needed before it stops forming a white cloud.
Calculate how much HCl is needed for the whole solution. And add a little less to your solution, then start adding in small increments.
You can switch to table salt in the end to avoid creating Aqua Regia.
Let it settle and siphon off the liquid. This is now mainly a solution of Copper Nitrate.
The Solid needs proper washing and rinsing, keep the washes in a container of its own or mix it with the other if you have he time to evaporate.
Now you have clean Silver Chloride to process, there are two common methods for that, Lye-Sugar method or Iron-dilute Sulfuric method.
The rest of the solution is well explained by Lazersteve and others.
It might be wise to evaporate it a bit though.

Thank You for the info. Just a couple more questions.
Should I put Back on heat while adding HCL ?
Should I Use Tap Or Distilled Water ?

 

[Yggdrasil]

Thank You for the info. Just a couple more questions.
Should I put Back on heat while adding HCL ?
Should I Use Tap Or Distilled Water ?

No need for heat and when dealing with Silver, ALWAYS distilled water.
In this setting, water is only for washing.
For the washing, not so important with distilled, it is already in Chloride form.

 

[jimbo12]

No need for heat and when dealing with Silver, ALWAYS distilled water.
In this setting, water is only for washing.
For the washing, not so important with distilled, it is already in Chloride form.

No need for heat and when dealing with Silver, ALWAYS distilled water.
In this setting, water is only for washing.
For the washing, not so important with distilled, it is already in Chloride form.

Thanks Again, Jim

 

[jimbo12]

No need for heat and when dealing with Silver, ALWAYS distilled water.
In this setting, water is only for washing.
For the washing, not so important with distilled, it is already in Chloride form.

Finished Silver came out good but If I want to denox my acid and cement out my copper without nitric recovery or heat do I denox 1st and than add my iron or later and what is the most economical additive to denox ?

Thank You

 

[Yggdrasil]

Finished Silver came out good but If I want to denox my acid and cement out my copper without nitric recovery or heat do I denox 1st and than add my iron or later and what is the most economical additive to denox ?

Thank You

How much solution are we talking about here?

 

[jimbo12]

7-8 gallons

 

[Yggdrasil]

7-8 gallons

Ok.
So you are doing this mostly to get rid of the toxic copper in solution, true?

 

[jimbo12]

yes and or copper recovery

 

[Yggdrasil]

yes and or copper recovery

Well there is less than a USD worth of Copper so I consider that as waste treatment.
9 ish USD per 2.2 pounds of Copper, current spot. Will give your Copper a value of 0.6-0.7 USD
So I recommend you to search and read the sections on dealing with waste.

 

[Yggdrasil]

yes and or copper recovery

The value of the Nitric is probably way higher than the value of the Copper.