Aqua Regia vs. Acid Peroxide.

[NuggetHuntingFool]

I'm curious as to why you guys use Acid Peroxide instead of Aqua Regia in the first step (most of you).

It seems to me that Aqua Regia skips a step in the process by dissolving the gold in step #1. Whereas with Acid Peroxide you have to strip the foils, then dissolve them with Acid/Chlorine in step #2.


Is it a safety thing?
Cost?
Efficiency??

I'm still learning, but I hope this isn't too "green" of a question.

Thanks

 

[NuggetHuntingFool]

Sorry moderators. I didn't realize there was a "Chemical Processes" section that would have been more appropriate for this question.

Please move if you desire.

Thanks.

 

[lazersteve]

NHF,

AP removes the base metals and leaves the majority of the gold intact. This makes for cleaner gold once it is dissolved and uses zero nitric acid (expensive and hazardous). It takes a lot less AR (or HCl-Cl ) to dissolve the small amount of foils after removing the base metals and provides for cleaner gold precipitations.

Steve

 

[Harold_V]

Is it a safety thing?

Smart people don't recover gold with AR unless there's a good reason to do so. Eliminating base metals is always in your best interest, and that normally is not accomplished with AR. If you were to recover values from non-metallic objects, where the substrate does not become a part of the solution, AR is generally acceptable. When values are plated over base metals, it's not a good idea at all.

Cost?

Assuming you are able to buy nitric to make AR-----cost is generally not a factor. As much acid, overall, will be consumed by dissolving with AR directly as compared to eliminating base metals with nitric (or HCl) prior to dissolving the values. As Steve alluded, the benefits of doing so are achieving a much higher level of purity from the precipitated gold. Even with a selective reagent, gold that precipitates has a tendency to drag down anything that is in solution. When precipitating from solutions that are heavily laden with base metals, the end result is less than decent quality gold----even after washing well with an accepted washing procedure. There is no better way to insure high quality than to minimize garbage in solution.

Efficiency??

Likely not a major factor, although gold that is dissolved with considerable garbage often filters poorly. By incinerating at the appropriate time, and doing preliminary processing by acid, either HCl or nitric, depending on the nature of the material, the remaining solids (the values) will usually be far easier to filter after dissolution.

I'm still learning, but I hope this isn't too "green" of a question.

Not in my opinion. As you refine, you'll recognize problem areas that may be difficult to avoid, but with experience and a good understanding of the refining process, you'll generally learn methods that will eliminate, or at least minimize, given problems. The preliminary washes are a good example. A solution that may have been contaminated with tin can be very troublesome to filter, yet incineration and a preliminary wash in HCl eliminates the problem entirely. Beginners don't know that, and generally don't have enough imagination to solve the problem.

Harold

 

[NuggetHuntingFool]

Gentlemen,

Thanks for the replies. You've cleared up a lot of questions and curiosities in one post for me.

So basically when I'm panning and in my black sands I'll run AP through them so I can dissolve the contaminants and leave mostly precious metals (hopefully)?

Another question if you would.

Does HCL/Bleach dissolve other precious metals, or only gold?

Does it do Pt, Ag, Au?

Or if I was on the hunt for Pt for instance would I require AR?

By the way. I downloaded that Modern Marvels episode about acids... totally awesome. All I ask is one barrel-full of that yellow Pt paste!

Thanks,
I appreciate the help.

 

[Oz]

As to “Does HCL/Bleach dissolve other precious metals, or only gold?” Yes but it will give you silver chloride. Also on the PGMs it depends what forms they are in.

“Or if I was on the hunt for Pt for instance would I require AR?” if Ag is present again you will get silver chloride.

 

[NuggetHuntingFool]

So basically the silver is dissolved first in each instance of HCL/Chlorine and AR?

If I mad a mixture of gold and silver the chemicals would dissolve the silver first. Once it's finished with the silver will it start on the gold or will it leave the gold alone?

Will it dissolve both at the same time?

What if you had Au, Ag, and PGM's? How would you guys attack them, let's say for instance that there weren't other contaminants, just the three and you only had acids at your disposal.

Thanks,
Great info.

 

[Anonymous]

I tried chemicals with black sands, all I can say is it takes a lot of acids to
dissolve that stuff. It did not work out for me, but, you may have a richer source.

 

[Harold_V]

So basically the silver is dissolved first in each instance of HCL/Chlorine and AR?

If I mad a mixture of gold and silver the chemicals would dissolve the silver first. Once it's finished with the silver will it start on the gold or will it leave the gold alone?

In both instances, silver will NOT dissolve. If it is present in great enough volume, nothing will dissolve. You can not dissolve silver with a chloride. It will yield silver chloride, if anything. Generally it does nothing.

What if you had Au, Ag, and PGM's? How would you guys attack them, let's say for instance that there weren't other contaminants, just the three and you only had acids at your disposal.

Thanks,
Great info.[/quote]
You'd be in trouble. Once silver and the platinum metals mix, they will dissolve along with silver, using dilute nitric acid----so separating them can be involved. They are generally best recovered when parting silver in a silver cell.

READ HOKE! I don't care if you buy a copy or download a copy-----do it before you proceed further. These are fundamental things you should understand before refining. It can prove to be valuable information, preventing you from tossing values, or understanding why your metal isn't doing what you hoped it would.

Harold

 

[NuggetHuntingFool]

Harold, I actually clicked on your link and my copy arrived via UPS today .

I'm looking forward to the read.


Thanks

 

[Harold_V]

Very good!

Much of what you want to know will start making sense. Best of all, you'll be able to ask questions that make sense because you'll have a better understanding.

I'd enjoy a report on your opinion of the book. Others may need the shove to make the choice to buy. They might appreciate comments beyond mine in that regard. I have no doubt many think I profit from the book. I do not. I am not affiliated with the book, or its sales, in any way.

Harold

 

[NuggetHuntingFool]

You might as well post more links to other good books in your signature too... You're a huge wealth of knowledge.

I will post an opinion of the book when I've read some more.

As far as making money from the book... it wouldn't surprise me if your knowledge has made you millions already...

Thanks.

 

[Anonymous]

NHF,

AP removes the base metals and leaves the majority of the gold intact. This makes for cleaner gold once it is dissolved and uses zero nitric acid (expensive and hazardous). It takes a lot less AR (or HCl-Cl ) to dissolve the small amount of foils after removing the base metals and provides for cleaner gold precipitations.

Steve

If I may add a quick question to clarify this conversation in my mine.

THE AP solution will not dissolve gold only base metals.

so I am to assume the greenish liquid i have after treating my gold pins is waste?

 

[arthur kierski]

peroxide +hcl dissolves gold, pt and pd ---i do it almost daily

 

[NuggetHuntingFool]

Are you sure AP dissolves gold??

From what I've seen it doesn't.


Steve uses AP in his videos and the gold remains in solid-form. However, the base metals are another story!


??????????

 

[Anonymous]

I think he ment HCL and clorox. Acidic peroxide only seams to strip the copper underneath.

This still leaves my question hanging. Is my green solution full of foils waste? Or should I keep it in some hope that values lie within?

should it be tossed after filtering?

 

[NuggetHuntingFool]

Well if it dissolves copper then it might just be of some value eventually.

I've been reading Hoke's book and she states you can leave your filter papers to dry for recovery of material at a later date.

I guess if you eventually build up a good supply of copper-infused filters it could be worthwhile. No?


I'm not sure though, but I suppose one of the high-ups in this forum will give us a good answer.

 

[Scott2357]

If there is too much peroxide(use 3% to be safe) or solution is too warm, gold will dissolve.

 

[NuggetHuntingFool]

Which just proves how little I really do know!

 

[Harold_V]

should it be tossed after filtering?

When handling solutions that have contained precious metals, be they dissolved or not, nothing should be discarded without first testing with stannous chloride that is known to be active. A follow-up test with salt or HCl for traces of silver is also a good idea. Even well experienced refiners exercise these tests.

Harold