Nitric Acid Elimination

[EVO-AU]

Everybody: Yeah, you too, my usuals ( you know who you are )..

Doggone it, I would like , no I want a definite , simple method of eliminating nitric acid from A/R. Yes, I have tried a bunch, including evaporation ( sucks ) ... PLEASE ? ! ?

Sincerely, Phill

 

[goldsilverpro]

Never use an excess of nitric when using aqua regia. Use an excess of HCl and then add the nitric in small increments. Only use enough nitric to dissolve what you are dissolving. If you do this, you won't have to worry about eliminating excess nitric because there won't be an excess.

 

[teabone]

Urea works well for me.

 

[lazersteve]

Truer words were never spoken GSP.

Too many times with chemical reactions people think more is better when performing reactions. Closer to the truth chemistry requires a bit of up front math before you begin your reaction to ascertain the volumes of the acids needed.

Phil,

If you are using poormans AR (sodium nitrate and HCl) you can add the sodium nitrate in small amounts just as if it were nitric acid. Be sure you heat the reaction for a short period longer after the bulk of the reaction dies down after each addition. Also add in very small increments as the foaming will overflow your beaker.

This procedure also cuts down on fumes.

Alternately you can use Harold's trick of adding a known mass of gold button to the reaction to use up any remaining nitric. Keep good notes on what you add so you can determine the correct yield data for the batch.

Lastly, Urea does work.

Steve

 

[EVO-AU]

Gentlemen: I have tried urea, but the stuff I have is about 18 months old. It came from a kit ( Shor ) that I got suckered into when I was investigating boards. I don't play 'round with boards and stuff. I work only with ore from Mother Nature. Does urea loses its' potentcy after time ? Poormans' methods aren't in my realm.. I purchase everything from Action or Elemental. I use HCL from Lowes', but there is too much other stuff in the solution to give me acurate results.

Steve - have you ever worked with Hydrazine ? I acquired some from a friend and am a little wary of it, but as soon as I have a decent bit of heavies,I'm going to give it all hell !!! Any ideas ?

Thanks all, Phill

 

[oef62nd]

EVO

UREA works if you have the right urea 46-0-0 I Have 50 lbs and will sell you some just PM me


Keith

 

[Noxx]

I found out by experience that gold produce from Urea will be less pure. In fact, as soon as you add come chemicals, you also add a tiny amount of contaminants.

I follow GSP and Harold's tips: I use as less as possible HNO3 and I do one evaporation. This way, I believe you can produce very pure gold.

 

[jaun]

I dilute the AR with 5 x water and precipitate with smb.
In have tested all my solutions every time after precipitation, and all the gold precipitated!

But like GSP and lazersteve said, don’t use excess nitric.


8)

 

[markqf1]

It takes time and experience to learn that you don't have to do everything "by the book".
The common AR recipe is what it is, to make up for the lack of experience of most.

Mark

 

[teclu]

I dilute the AR with 5 x water and precipitate with smb.
In have tested all my solutions every time after precipitation, and all the gold precipitated!

But like GSP and lazersteve said, don’t use excess nitric.


8)

Jaun Hi!

Please tell me if I understood correctly: if the nitric is kept under control(used not in excess) and AR is diluted with 5Xwater, then the precipitation will run in good conditions everytime....my question is: without evaporation or urea?

Did someone else try this technique?.... Other opinions?


Thanks!

teclu

 

[teabone]

Excess water works fine , but the drawback is a large volume of wastewater to deal with.

 

[goldsilverpro]

The purpose of the dilution is to precipitate the silver chloride that may be dissolved in the strong acid. After dilution, the silver chloride can be filtered out. If you don't do this, the silver chloride can contaminate the precipitated gold during the rinsing (dilution) stage. Early in my career, I did some experiments to determine the amount of dilution needed to prevent this contamination. I found that a 3 to 1 dilution was most effective. At that point, the curve leveled out and continued dilution did not precipitate much more silver chloride. Therefore, a 5 to 1 dilution can be overkill, unless an excess of nitric has been used. All it does is create a larger volume of solution that must be filtered.

When excess nitric has been used, it is possible to dilute the solution enough (some say 10 to 1) to allow the gold to precipitate. However, this causes much more filtration and slows down the process. As I've said many times, the trick to all this is to never use more nitric than is needed to dissolve the gold.

 

[Lino1406]

Do not use hydrazine with nitric acid
(strong reducer + strong oxidizer = boom!)