Final refining gold, - brainstorming

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Yes Sir- my method is neither of the methods described in your links.

Maybe we have a language issue here that isn't helping as it's possibly causing some misunderstanding Solar.
 
Maybe we have a language issue here that isn't helping as it's possibly causing some misunderstanding Solar.
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Maybe. I talk chemistry. Maybe you didn't mean conc. sulfuric acid and you didn't mean H2O2, I don't know. But that is, what you described.
 
I'm not going to lower myself to squabble with you on a public forum Sir.

You don't know enough about what I mentioned to make a proper judgement call. You heard Sulphuric acid and Hydrogen peroxide and made a whole host of assumptions.

Let's leave it at that and move on.
 
If you have access to Sulphuric acid you can also take out a lot of copper using the sulphur/peroxide method.

It's not one that's commonly described but it's a great way for getting the remains of the copper out of your powder and it's a completely controllable reaction, even though of course concentrated sulphuric acid is an extreme hazard.

Jon
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That's what I heard. Cónc. sulfuric and peroxide, where I assumed you meaned hydrogen peroxide, which was mentioned later and I don't believe, that you have contradicted that. Those two are something quite dangerous and even if only unpropper mixed tend to explode while heating to 120°C, not to mention, what will happen, if they are used uncorrectly. Controllable? Yes, a controlled demolition is also controllable, but not by everyone who reads this thread.
 
solar_plasma said:
Those two are something quite dangerous and even if only unpropper mixed tend to explode while heating to 120°C
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Having carried out this process with Spaceships, and having read his posts above, heating of this process to 120c has never been mentioned, nor is heating part of the process.
The very process is exothermic, providing all the heat that the reaction requires, the hydrogen peroxide is used to oxidise any copper in the gold powders and then with the addition of the sulphuric acid the copper oxide, produced by the previous reaction, is dissolved.
 
martyn111 said:
Having carried out this process with Spaceships, and having read his posts above, heating of this process to 120c has never been mentioned, nor is heating part of the process.
The very process is exothermic, providing all the heat that the reaction requires, the hydrogen peroxide is used to oxidise any copper in the gold powders and then with the addition of the sulphuric acid the copper oxide, produced by the previous reaction, is dissolved.
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I'm hoping that one of you will provide some details to the process so that we can all understand how it is different than piranha solution. Bickering back and forth without explaining the details isn't helping anyone and it just adds to the clutter.

Dave
 
martyn111:
heating of this process to 120c has never been mentioned, nor is heating part of the process.
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I have mentioned it. When you mix the two chemicals, heating is part of the process:

wikipedia:
Mixing the solution is exothermic. The resultant heat can bring solution temperatures up to 120 °C. It must be allowed to cool reasonably before applying any heat. The sudden increase in temperature can also lead to violent boiling, or even splashing of the extremely acidic solution.
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Lou:
Re: piranha and base piranha in refining?.
No use in anything we do.
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I'm not going to be drawn into a P*ssing contest with anyone over this.
Solar, re read my post and you will see that i mentioned that the reaction is exothermic, so please explain your reply.
The full process has not been explained due to your insistance that conc sulphuric is the devils spawn although this is the same chemical used in the gold stripping cell.
You may be in a position that you use chemicals everyday in your work, therefore you should be aware that all chemicals if handled incorrectly are dangerous but can also be a very useful tool when used correctly.
Had you not jumped down Jon's throat the minute he mentioned conc sulphuric and hydrogen peroxide in the same sentence then a fuller explanation of the process could have been made.
 
Right Ok Solar.

Here's the process (against my better judgement if the truth be known). When reading it I hope that you recall that you never asked WHAT I was doing, you made a load of assumptions based upon the chemicals involved.

For reference please use all appropriate safety procedures:

Take your dirty Gold powder and place in a cleaned glass jar.
Cover to a depth of 1cm with distilled water. Measure the amount of water used. This should allow for the use of different sized containers.
Add Concentrated (yes the devil liquid) Sulphuric acid to the water to the same quantity as the distilled water previously added.
Stir gently with a glass rod to ensure it is fully mixed.
Add Hydrogen Peroxide from a pipette, one or two drops.
You will see the gold begin to fizz slightly as the reaction occurs. At this point you will see blue liquid (Copper sulphate) start to enter to solution. This is the copper being leeched out of the gold.
Stir gently to ensure all the peroxide has been used.
Add another drop or two of peroxide, then rinse and repeat until no further reaction occurs and the solution doesn't get any more "blue."

It's controllable - by the limited use of the peroxide. It's not what you have been referring to in your previous posts.

Imagine that it's a lateral thinking approach to the standard forum use of AR. Nobody uses standard mixed AR - they DRIP the Nitric acid in so there is no excess. I welcome comments.

Jon
 
I don't jump in anyones throat. There was nothing offending in what I said. If you two fellows try to make a personal thing of it, you can do it. I don't mind. I discuss facts.

The problem is, you talked about conc. sulfuric and H2O2, never mentioned you really meant dilluted sulfuric. That is what you actually are using. Yes, it's amazing how fast it eats the copper. But as I said, even dilluted it is violent stuff, not to compare with sulfuric. And reread, what I wrote: no one who reads this should think of using it full strength - leave it to professionals who know its dangers and proper use! (unless he is a professional).


Where do you two guys have a problem with this?

I never said, it couldn't be used dilluted, - only that it is still extemely hazardous, if you don't know to handle it, not to compare with sulfuric under 100°C or AR, those are pussy cats compared to this tiger.

On the other side, what benefit do you have with it, it does the same thing in seconds, hot dilluted sulfuric would do in half an hour. Impatience could be a reason to use it. The more I learn about refining, the more I try not to be impatient.
 
Whew! Glad you guys got that out of your systems.

Jon, thanks for posting the details of your process. It's obviously quite different than piranha, though it starts with the same chemicals. I find the process interesting in the approach of adding the peroxide dropwise to diluted sulfuric acid, just like adding nitric in increments when making AR.

Perhaps now that the process has been described, we can get some others to opine on it.

Dave
 
If you do not say what you mean,or explain your comments well, and you do not state details the best you can, or explain what you are trying to say in detail, you leave what you say up to assumptions, where the reader has to assume, or you leave your comment up to assumption of the reader, where you can be easily misunderstood.

Also with many of us here speaking different languages there are also problems with translating the messages, which can further lead to confusion.


Solar was assuming with safety in mind for other readers, and without better details what else would be expected, without more details many of us here concerned for others safety would do the same thing.

You should be clear of what you are talking about (as best as you can), especially when discussing a dangerous process, or one that someone can make assumptions of, and could become (in the wrong hands) a very dangerous process, with little details and assumptions of unclear statements, a very dangerous process could result getting a new member hurt or crippled for life.




I see no benefit to using the sulfuric acid (whether assisted with H2O2 oxidizer or not), on these gold powders, in fact I believe it would be a mistake, especially if this material came from electronic scrap, where any remaining lead in the gold would form an insoluble lead sulfate, contaminating the gold and making it brittle after melting.

With the normal process we use and the gold washing procedure of the gold wash we can eliminate lead as a soluble chloride in boiling hot water rinses.


I see no benefit at all to using sulfuric acid to dissolve copper (over the conventional copper II chloride leach), whether you are speeding up the process with a little O2 addition from H2O2 or not.
there are times where I choose to use sulfuric acid to remove base metals (sometimes even as a replacement for nitric acid a process I will not go into detail because of its dangers), but for general use I like the copper II chloride leach to dissolve copper (when nitric acid is not an option) especially for fine copper metal from electronic scrap, the chemicals are cheaper (for me), and I can rejuvenate the CuCl2 leach for very little cost, and reuse it again, this not only lets me dissolve more copper for less money but also helps to lower cost and trouble in the waste stream (although when I do make copper sulfate it is normally reused in other processes).

Actually I believe you can dissolve gold as a sulfate if the H2SO4 acid and H2O2 where concentrated enough (extremely dangerous process, which would just be stupid to try), but the gold would not stay dissolved long as a persulfate of gold, as I believe it would be unstable as a gold persulfate,. My thinking on this would not be much different than using the concentrated sulfuric acid gold deplating cell where gold is dissolved at the anode, but as the gold per-sulfate leaves the highly oxidizing environment of the anode area the unstable gold per-sulfate converts back to gold metal powder and sulfuric acid, also similar to this process in the electrolytic cell, a strong peroxymonosulfuric acid H2SO5 would likely passivate copper (with an oxidation layer) at least until the solution lost its overly strong oxidation power.

Again I see little benefit here with this method of using sulfuric acid to dissolve copper making copper sulfate.
 
spaceships said:
I think you're wrong to tell me off for mentioning a process that is actually valid. It's not some half baked lunatic idea, it's based upon valid and accurate chemical process.
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Please adjust your attitude. You were not "told off". We have a policy on this board to restrict any suggestions that can prove to be a bad decision on the part of the unknowing. Concentrated sulfuric is known to be quite hazardous, so the cautionary note was acceptable. We generally advise against its use, especially when heated. We also expect readers to speak out when they read anything that presents unnecessary risks.

The real problem we have is having readers who often have little to no chemical training, and are not in tune with the hazards that may be present. For example, we are typically unwilling to discuss much about HFl, strictly because it presents hazards that can be life-threatening.

Assuming you have a process in mind that tends to lean towards being rather dangerous, and you wish to discuss it to some end, you should be the one to present the warnings. Do not assume that because you have an understanding that others share your knowledge. They often do not. We do not endorse anyone's use of the board to promote a process that offers unnecessary risks.

Harold
 
I've tried to follow this dog and pony show, and am less than impressed. I'm at a loss to understand why you must re-invent the wheel? What possible reason would one have to use the sulfuric process? To think that ANYONE would spend as much time defending a process that has no real practical use, as has been expended on this one, is beyond my understanding. It is my opinion that this entire matter needs to come to an end. Do you get my drift?

You want to wash your recovered gold with better odds of eliminating copper? Long before I'd choose sulfuric, I'd choose nitric (and I recommend that it not be your choice). The problem is, you're working with a substance that has been recovered from a chloride, so you risk dissolving some of the gold along with the unwanted base metals, which would even include lead, very unlike sulfuric. That, in and of itself, should be reason enough for this sulfuric process to be eliminated from use. I won't go in to the difficulty of eliminating all of the sulfuric after the wash has occurred.

We've been through this before---and there's more than good reasons why we wash our gold as we do. We use the procedure we promote because it works (and damned well, if you don't see yourself as being clever, and avoiding doing it properly), and it offers the least possibility of risk.

Get on with things of substance, and put your damned egos in neutral.

Harold
 
In all my chemicals i fear and respect sulfuric the most. True it can be handled properly and safely, but i'm a man of probability. In a game of chance the sure way to beat the house is you don't play in the first place. The only time i use sulfuric is to remove lead. I've run a very successful hobby with just Hcl, nitric, smb, and urea. Some people don't even use urea, but with my batch sizes nitric acid is always in excess and solution volume is such that evaporation or use of a gold button is not feasible. Some people only need these three basic chemicals and you can produce quality gold time after time. A gold refinery can be had for very little investment compared to the returns. The wealth of the refinery comes not from it worth, but from one's knowledge.
 
I have read that diluted sulfuric in a cell will desolve gold.
if you dilute sulfuric and add h2o2 would it not desolve gold,
and if sulfuric needs to be diluted,why not just start with
battery acid,already diluted,instead of 98% sulfuric.
I would like to understand these points.
thanks john
 
Sulfuric acid doesn't dissolve gold unless another oxidizer is present.

That's part of the reason the sulfuric acid stripping cell works--it generates peroxysulfuric acid in situ which is a transient species that dies off, putting the gold back in ground state as a black/brown powder that will settle.


If you're talking about cleaning up gold after chemical reduction you need to consider several things:

1. Is it contaminated with silver chloride?
2. Is it contaminated with other base metals?
3. How was it precipitated-- copperas, SMB, oxalic?

If you suspect AgCl contamination, that's where an ammonia wash is indicated.
If you suspect other base metals, warm, 70% sulfuric acid is highly effective at removing those, including Pd.

If it was precipitated with copperas, expect iron contamination, especially if solution was dilute and not highly acidic. If it was reduced with SMB, expect palladium and/or copper (I) chloride contamination, if it was reduced with oxalic but was a dirty solution, expect copper oxalate contamination (and other metals that form insoluble oxalates, particularly rare earths and alkaline earth metals (Ca+2).

No need to use peroxide in any situation for cleaning up Au, unless you're redissolving it!
 
So,

if I have used SMB (gold (medium brown), source e-scrap, possibly contaminated with everything common to e-scrap)

washed with hot 36% HCl (Pb, Cu, edit: all or almost all other base metals)
washed with boiling water (Pb)
dissolved all AgCl with NH4OH (then made the filtrate acidic again with HCl to avoid unstable silver compounds and precipitated AgCl)

will there be anything left I could remove with
warm sulfuric 70%
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?

Isn't the Pd already dissolved in HCl?

EDIT:
Already answered:
If you suspect other base metals...
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Thanks!
 

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