# Oxalic method



## Paige (Jun 19, 2007)

When I pour the boiling gold solution into the boiling oxalic acid, do I need to worry about boil over? If the nitric is gone, is it going to bubble up and over my vessels? How much capacity should I have?

Pregnant solution 500 mg.
Oxalic solution 500 mg.

Should I have at least a 2 liter container or is the reaction rather tame?

Paige

And I wanted to thank all of you who take time to help me. I really appreciate it. Professor Steve in Virginia taught me so much, I can never repay his kindness. But this forum is great! What a super collection of great minds to help out us dummies.


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## lazersteve (Jun 19, 2007)

Paige,

It sounds like you are not doing something correctly. 

First off nothing should be boiling. Fill your clean separatory funnel with 250 mL clean BDG.

Secondly, if you used AR to process your gold, the BDG and AR solution are shaken in the separatory funnel to strip the gold chloride out of the liquid *before* the golden yellow BDG goes into the oxalic acid mixture. The AR is stripped in portions. Add a 250 mL portion pregnant AR solution to the funnel and shake vigorously. Let it settle and drain off the AR into a separate container. Repeat until all the AR has been washed with the BDG. Be sure the two liquids completely separate in the funnel before draining the lower layer off each time.

Next the BDG layer is washed by shaking in the separatory funnel 3-5 times with *diluted* HCl. The HCl washes are drained off of the BDG and combined together in a separate contianer for testing and disposal.

Lastly the BDG is added to the oxalic acid dissolved in water and stirred over a gentle heat. There will be two separate layers while this is happening. The stirring helps the oxalic solution contact the Auric Chloride in the BDG to drop the gold as beautiful gold flakes. Stir until the upper layer is clear again.

Reuse the BDG after filtering out any gold flakes.

This is a very brief descripiton so feel free to ask questions. It would help me to understand where you are at in the process if you fill me in on your endeavours up to this point before you go any further. Photos would be very helpful.

Steve


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## NobleMetalsRecovery (Jun 19, 2007)

I think I can help clarify what Paige was referring to about the boiling AR and the boiling Oxalic acid solutions. In Ammen's book on Gold Refining he includes a method to precipitate gold from an AR solution. That method requires the AR and the Oxalic acid to both be boiling. Also, with that method the precipitation is almost immediate.


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## NobleMetalsRecovery (Jun 19, 2007)

A question for Steve on the BDG system . If AR was used to digest the gold Ammen says the nitric acid content should be less than 1/10 M before stripping it with the BDG.

Do you know if adding Urea will do the job? Are you doing anything to get rid of the nitric?


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## lazersteve (Jun 20, 2007)

Steve,

I don't have any hard data on the acceptable levels of nitric when using BDG. I've used BDG to strip gold from H2O2-HCl and HCl-Cl soluitons only. I assisted Noxx with a batch of AR using BDG and he didn't neutralize the nitric as far as I know. The literature that I have (not Ammens) claims BDG will work on AR solutions without the need to neutralize nitric acid.

If you have any other data on using BDG with AR that would be great.

Steve


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## Paige (Jun 20, 2007)

Thanks LazerSteve; Steve was right about where I got the boiling oxalic information. I think that I have it down now. My "mud" has been thru AR twice and am hoping putting it thru this solvent way will get me on the road to .9995+.

Obviously, I only do this for a hobby, and stand in awe of you folks who do it professionally, but it can get to be an expensive hobby, so I am really trying to conserve and be careful. 

My attempt at cell usage to strip plate wasn't very successful, probably because of poor quality of stuff to be deplated. But closing that out are questions for another post.

Lazersteve and Steve, Thanks. Paige


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## Noxx (Jun 20, 2007)

Exactly lazersteve, I did not neutralise the acid. The AR was still very acidic. And I achieved good results.


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## NobleMetalsRecovery (Jun 20, 2007)

Not too surprised to hear that it worked. It's nice to know of a way to drop gold with nitric acid still present. 

I think the incentive for removing the nitric acid is to preserve the quality of the BDG for reusing it.

Any details available on the process you used to drop the gold from the BDG?


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## Noxx (Jun 20, 2007)

Yes, I made a tutorial on how to use BDG. But I haven't finished it yet. But today I finished school ! Yay ! So I will have the time to complete it and publish it.


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## lazersteve (Jun 21, 2007)

Diethylene glycol dibutyl ether said:


> *Chemical Stability:* Stable under normal temperatures and pressures. Absorbs carbon dioxide from the air. May decompose violently on contact with nitric acid.
> *Conditions to Avoid:* Incompatible materials, excess heat, strong oxidants.




The MSDS for 98% BDG supports a reactivity with nitric. Note however the stipulation ('may') and result of the interaction ('decompose violently'). From this I would surmise you would certainly know it if this decomposition were taking place. It would also seem that excess heat is not recommended and may even promote decomposition under certain conditions.

Good information to know. I'm going to see if I can locate some more precise numerical data on this subject.

Steve


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## aflacglobal (Jun 21, 2007)

But today I finished school ! 

_*Congradulations!*_
What was that GPA ? No i don't mean Gold prospectors assoc.
Grade point Average.

Your ready for a job now. :wink:


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## Paige (Jun 21, 2007)

Congratulations?


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## Noxx (Jun 21, 2007)

Thanks Aflac. Well I finished High School, now I'm going in Chemical engineering at the end of the summer.

I'll try to work for myself (how do you call it?) this summer, trying to start my own business. 

What is Grade point average, could you explain please ?

Thanks


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## lmills148 (Jun 21, 2007)

Noxx said:


> Yes, I made a tutorial on how to use BDG. But I haven't finished it yet. But today I finished school ! Yay ! So I will have the time to complete it and publish it.


congradulations


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## NobleMetalsRecovery (Jun 21, 2007)

Thank you Lazersteve for bringing attention to the potential hazards of BDG in connection with nitric acid, and perhaps also for AR solutions. I will proceed with greater than normal caution until more is known.

I have been neutralizing the nitric acid in the AR solution with urea before adding the BDG. I did this out of concern for reusing the BDG, not being aware of the potential hazards of nitric acid and BDG. Think I'll re-read the MSDS that came with the BDG.


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## aflacglobal (Jun 22, 2007)

What is Grade point average, could you explain please ? 

I forgot canadians do things different. lol

GPA means how high or low was your score.
A = 90-100
B=90-80
C=80-70 
D=70-60
F=60 and below. The percentages are an average of how well you scored on subjects. Now i think they use the standard of 4.0 3.0 3.5 GPA Ect.


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## Noxx (Jun 22, 2007)

Well, I don't know it yet... I don't know my GPA for english, french and spanish. I know that I got 82% in Chemistry and 83% in Physics and 71% in Maths 536.


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