Free Nitric & preciping Au from AR

[kurt]

Ok – about a week ago I asked about the need to put AR through the evaporation process to remove free nitric before preciping with SMB - & in a reply posted by Nick he mentioned ---“The best method is to make sure you have no free nitric or failing that use Harolds method and dissolve a gold button to help consume any nitric left over”

So – this question is not one of - how to or what to do – but rather a question to see if I am understanding what’s actually taking place in the chemistry here.

So if I am understanding it right – when dissolving gold in AR – the free nitric is being consumed as the gold dissolves. So if all the gold is dissolved in your AR at the end – there is a likely hood of still having free nitric – therefore the need of the evaporation process to assure there is no more free nitric before preciping.

On the other hand – if once the AR has stopped working on the gold – & you still have un-dissolved gold – it’s because the free nitric in the AR has all been consumed & therefore AR that has stopped working & still has un-dissolved gold can/could preciped without going through the evaporation process.

Hence the above answer to my original question - “The best method is to make sure you have no free nitric (evaporation with the addition of sulphuric &HCL) or failing that use Harolds method and dissolve a gold button to help consume any nitric left over”

Meaning – you can precip gold from AR with SMB – without going through the evaporation process – IF – your AR has stopped working on dissolving the gold – AND – you still have un-dissolved gold in the AR? --- Because there is no longer any free nitric in the AR to complete the dissolving of the remaining gold? --- Or – is there some other reason to do the evaporation process – other then removing the free nitric?

Kurt

 

[Harold_V]

Meaning – you can precip gold from AR with SMB – without going through the evaporation process – IF – your AR has stopped working on dissolving the gold – AND – you still have un-dissolved gold in the AR? --- Because there is no longer any free nitric in the AR to complete the dissolving of the remaining gold?

That may or may not be the case. As you gain experience, you'll come to understand that an excess of HCl when dissolving with AR does no harm---but a lack of adequate HCl will emulate the same condition displayed when you have consumed all the nitric---there will be no further dissolution of gold. So then, the lesson learned, here, is that if you have an excess of undissolved gold present, you can readily determine if the reason is the lack of HCl by simply adding a little more. If you see further activity at the gold, it's clear, there was an absence of HCl. Do bear in mind, this should be conducted with heated solutions. Cold solutions are too slow to react, so the results may not be conclusive.

--- Or – is there some other reason to do the evaporation process – other then removing the free nitric?

Your objective may be to concentrate the solution in question. That's important when you process the platinum group, which generally does not precipitate well, if at all, from dilute solutions.

I preferred precipitating gold from highly concentrated solutions, so I evaporated, even when I knew there was no excess of nitric. I did so in order to keep the volumes in check. Concentrated solutions of gold yield considerable heat upon precipitation, so ice must be used to cool the solution, assuming you're using SO2 for precipitation. That would include the use of SMB. A level of concentration in excess of three ounces per liter would be a case for needing ice.

Harold

 

[kurt]

Thanks Harold

I am begaining to see why I was so disapointed in the results I was getting when I first started playing with the refining proccess a little over a year & a half ago (& before finding this forum) --- I was going on LOTS of mis info &/or incomplete info - of which there is a HUGE amount of floating around out there on the net.

Example's (1) to make AR mix 1 part 70% nitric with 3 parts HCL - instead of the 1 part 70% nitric with 4 parts HCL as told to do in Hokes & on the forum here (2)Dissolve fingers & pins in enough AR to cover them - then add equal amount of SMB dissolved in water - let settle over night & "WaLa" in the morning you will have all the gold settled to the bottom which will be 24K (& never till I found this site did I ever here anything about testing solutions)

And thats the kind of info I was going on before finding this site - no wonder I was so disapointed in my results in the begaining

Kurt

 

[dtectr]

I, for one, appreciate your sharing your disappointments from "Anti-Info" (kind of like "antimatter", which causes a violent reaction when it comes into contact with "matter") floating around out there.

And, you seem to really want to learn - that will get you far here, as we're all still learning. We usually have 2 or 3 new folks a month, whenever gold goes up again, that bring that garbage info here, want us to fix their problems created by following it, then get mad at us for not telling them how brilliant they are.

Hopefully, you didn't throw away any of your solutions or residues - If there's still undissolved gold there, it can be recovered, once you've learned the processes well.

 

[kurt]

Hi dtectr

Unfortunatly I threw most of it out thinking - "well I guess thats all there was" in the begianing :evil: Luckly in the begianing I was playing mostly with very small batch's in trying to figure it all out However - I do have a few solutions hanging around from some larger batch's I tried just before finding this site so ya we can still work on that MESS once I am certain I have the proccess down working from start to finish on a few fresh batch's.

If I had to guess (cause only God really knows) I would say I have lost around 1 & 1/2 - 2 oz gold before find this site :evil: &

Kurt

 

[Harold_V]

One thing to keep in mind, which no one talks about that promotes the use of AR to process gold without addressing base metals--- is---once you have dissolved values, be they gold, platinum or palladium, if you do NOT dissolve all of the base metals at the same time, they will cement the values, so you have done nothing more than dissolve base metals in the end. That's acceptable, assuming you test routinely and know when to discard the solution before adding more acid, but rarely does anyone understand what's going on---so they don't.

The big mistake they make is to stop when action ceases, then attempt to recover their values, not understanding that they have long since cemented----or that there was some base metal remaining, which, in turn, cemented some of the values until it, too, had been dissolved (by the cementation process). Testing still reveals values in solution, with a percentage now cemented and possibly discarded with what the "refiner" (a term I use loosely) deems to be waste material.

Assuming neither of the two scenarios occur, and all of the metals are successfully dissolved, the resulting value is so dirty it borders on the impossible to wash adequately to pass an acceptable level of acceptance. A second refining, in this case, isn't an option---it's mandatory.

I have gone head to head with many since moderating this forum-----often with a smart remark about there being several ways to skin the cat.

Yep---there is.

Trouble is, most of them yield inferior results.

We promote processes on this board that guarantees acceptable results, and typically offers the least risk, both to the operator and ecology. You are setting an excellent example of how readers should react when being told what they're doing isn't wise. Too bad others don't follow your example.

Harold

 

[nickvc]

Kurt you seem to be heading in the right direction and I see you becoming a valued member of the forum.
I for one look forward to hearing how you proceed and will be waiting for news of your successes which I'm sure will come in the very near future.

 

[kurt]

YES – FINALLY – Real Success with Real Results --- don’t have time to post pics &/or detail right now as I need to get ready to go over to my brothers place & help him do some work on his observatory. He’s into astronomy BIG TIME & the cement pillar he mounts his telescope to heaved & shifted over the winter so we need to dig it up, pull it out, big it down deeper & reset it. So I will be busy with that for the next couple day & then I will post pics & details.

I AM JAZZED !!!

Kurt

 

[Wyndham]

Harold, if I understand what you said, AR can & will dissolve everything(metals) and the excess non value metals will cement out the gold values as well as some of the other metals creating a"Dirty" precipitant, then test for values and drop those values out so everything in the solution(Ideally) is dropped then you could use a process that just takes out the non valued metals that have cemented out leaving just the gold precipitant. I'm leaving out the other parts like diluting, filtering, washing, incinerating because I'm not sure which comes where right now, I'm trying to understand the basic part here. Have I got it anywhere close? Thanks
Wyndham

 

[goldenchild]

Harold, if I understand what you said, AR can & will dissolve everything(metals) and the excess non value metals will cement out the gold values as well as some of the other metals creating a"Dirty" precipitant, then test for values and drop those values out so everything in the solution(Ideally) is dropped then you could use a process that just takes out the non valued metals that have cemented out leaving just the gold precipitant. I'm leaving out the other parts like diluting, filtering, washing, incinerating because I'm not sure which comes where right now, I'm trying to understand the basic part here. Have I got it anywhere close? Thanks
Wyndham

AR will dissolve most any metals and will cement out your gold only as long as there is undigested base metal in solution. This can be tough to do if you aren't experienced in using AR opposed to an inquartation process. This is why Harold is a strong advocate of getting rid of all the base metals first (recovery) and then processing the left over gold (refining). Especially when you are just starting out in this business/hobby.

When using AR to go straight to refining it may leave pieces of gold behind that were undissolved but don't appear to be gold bearing. To someone starting out this could spell losses in the way of disposing valuable material.
I know Harold won't like this since it's goes against what the this forum is more geared toward but I hope that he'll see that it will help answer your question and bring light to alternative methods (viable ones that is).

I use AR in the primary chemical steps of refining. Mostly for gold filled scrap. Mainly for speed's sake and chemical savings. This is after becoming very familiar with the inqartation method and recovery/refining practices in general. Enough to feel comfortable trying to refine directly with AR.

The key to processing the scrap successfully using AR is ensuring 100% digestion. This means only leaving behind silver chloride and other materials that can't be digested such as dirt or Rhodium. The resulting solution would then be filtered ridding the solution of these "free radicals" and the gold would then be precipitated. After precipitation the gold would be separated from the solution and the necessary processes follow. I think this answers the pieces of the process you wanted to know.

In hopes of getting back on Harold's good side again right away, I will say this :mrgreen: Incineration is extremely important when using AR as a primary process! You won't be able to tell the difference between gold and dirt in a dark green solution.

 

[nickvc]

Harold, if I understand what you said, AR can & will dissolve everything(metals) and the excess non value metals will cement out the gold values as well as some of the other metals creating a"Dirty" precipitant, then test for values and drop those values out so everything in the solution(Ideally) is dropped then you could use a process that just takes out the non valued metals that have cemented out leaving just the gold precipitant. I'm leaving out the other parts like diluting, filtering, washing, incinerating because I'm not sure which comes where right now, I'm trying to understand the basic part here. Have I got it anywhere close? Thanks
Wyndham

You almost got it, what Harold was alluding to was that if you use AR to dissolve everything but leave some base metals undissolved any gold or values will cement out leaving a cleaner starting mix to dissolve again with little garbage amongst it, it's not a way to go for the beginner as it takes good judgement and experience.

 

[Oz]

Spot on Nick!

Who would want to precipitate gold out of such a dirty solution as you get when all is digested? Drag down anyone? You will likely lose PGM as well when chemically precipitating from such a dilute solution. As added benefits of leaving some base metals, you know all of your nitric has been consumed, and all of your values are neatly corralled into the corner of your beaker in a concentrated form.

As stated, if you are not completely fluent in testing, you will lose values with this method!

 

[goldenchild]

Guess it's not for everyone but the reality is, for the most part, this is how it's done on a larger scale. In a mid to large scale operation the scrap is shotted relying on mixing karats of lower and higher grades to obtain a respectable inquartation. Any undigested material is accounted for and reprocessed. Not being argumentative here but just trying to show that other methods are out there.

I will be processing a few pounds of gold filled soon and will try and document the process. The main thing that I want to show is that the dark green dirty solution is not all that bad if handled properly.

 

[Harold_V]

Harold, if I understand what you said, AR can & will dissolve everything(metals) and the excess non value metals will cement out the gold values as well as some of the other metals creating a"Dirty" precipitant, then test for values and drop those values out so everything in the solution(Ideally) is dropped then you could use a process that just takes out the non valued metals that have cemented out leaving just the gold precipitant. I'm leaving out the other parts like diluting, filtering, washing, incinerating because I'm not sure which comes where right now, I'm trying to understand the basic part here. Have I got it anywhere close? Thanks
Wyndham

AR will dissolve almost all metals (not silver, which it converts to silver chloride, for the most part, assuming it is less than 10% of the alloy), so if the process is carried to fruition, with no remaining base metals left undisclosed, the only real negative is that the resulting precipitate will drag down a serious amount of garbage, because it comes from a very dirty solution.

I think I understand your question, but I'd like you to look at it the way I'm discussing the issue----which is using AR without addressing base metals is clearly NOT a good idea. The only exception to that is when you desire to use the cementation process to recover the values for various reasons. The one good example I can cite would be when I received for refining, a large volume of dental material, in which there was a lot of base metal (high temperature alloy). I chose to separate the garbage from the values by dissolving everything, using AR sparingly, so all of the material would NOT dissolve. I wanted enough base metal remaining undisclosed to cement the values that did dissolve. When the AR had been exhausted, I had a mixture of values and base metals in solution. The remaining base metals then cemented the values, consuming yet more of the base metals, and recovering the values, which settled as slimes. When the solution tested barren, it was removed from the vessel and more AR introduced, again, not enough to digest everything. By repeating this process one or more times, you slowly eliminate the base metals, save for a small amount at the end, when all of the solids are dissolved and processed for values. By now, the amount of base metal that is present is drastically reduced, yielding a much higher quality precipitation.

The reason you should NOT use AR, otherwise, is because the conditions I discussed, above, exist, even when you may not intend for them to exist. As a result, gold can be, and often is, lost. Even when the operation is successful, the resulting gold is quite dirty---because it comes from what I'd call a filthy solution. There's nothing quite like inquartation to raise the quality of the gold before it's processed for purity.

Harold

 

[Harold_V]

I use AR in the primary chemical steps of refining. Mostly for gold filled scrap.

Blink! Blink!
Sorry, but that may just be the most stupid thing I've heard lately. There is nothing to be gained by processing gold filled material with AR ----absolutely nothing. You are dealing with, at best, 5% gold, which is often contaminated with tin and lead. I can't think of any better example to steer people away from direct dissolution than gold filled materials. They scream for the first digest in nitric to eliminate the troublesome materials that are present.

Have you processed eye glass frames? If so, have you done so in volume? I did, and routinely. Thousands of pairs, in fact. The resulting solution, even after eliminating base metals, was extremely difficult to filter. So much so that I incinerated the recovered values, then did an HCl wash prior to dissolution. I can't even begin to imagine the difficulty I'd have experienced by dissolving them in AR directly.

Mainly for speed's sake and chemical savings.

I'm at a loss to understand how you save anything with chemicals. In either case, everything must be dissolved. By dissolving all the garbage along with the values, the volumes of solutions are huge as compared to processing only the values. Brings to mind the need to evaporate. Which would you prefer, a few ounces of solution or a few quarts of solution?

Plain and simple.

Virtually ALL of the new readers that come to this forum have used AR to process, and, almost to the man, they have failed (that's why they're here). Gee! I wonder why?

The direct AR method should not be promoted, not any more than one would promote parking one's car in the garage by driving through the unopened door.

If you choose to process as you've described, I have no issues with your decision, but it should not be promoted on this forum---which has the potential to undo all the work we try to do to get these guys on the right track. All too many seek the easy way out, and it clearly is not. It just leads to the same failures and questions.

I'm getting damned sick and tired of answering the same questions over and over again, thanks to others not allowing this piss poor method to die the death it deserves. In a nutshell, AR is not a recovery process, with very few exceptions. but should be looked upon as a refining process.

Harold

 

[kurt]

Goldenchild

I really, Really, REALLY have to agree with Harold on this one --- The process of refining PMs by using AR to digest both base metal & PMs as a workable alternate refining process should not be suggested on this forum. --- That is just the kind miss information I was following for close to 1 & ½ years before finding this forum & only God knows how much value I lost following such bad instruction. (its been a LOT)

As much as it “may” be an alternate – workable – method – like me – MANY – of the people coming to this forum – have had there head “filled” with exactly that kind of instruction – from an internet FULL of exactly that as instruction AND they can’t figure out why they are not getting any value back &/or were it’s going --- And that’s because with such instruction there is NEVER any complete explanation of what is going on between the chemicals the base metals & the PMs&/or the effects of the base metals on the PMs as a result of the chemical reaction.

I am “just now” – “starting” – to get my head wrapped around it all & just now starting to have “real” success – after finding this forum & following the WISE instruction of this forum (& Hokes – which I found thanks to this forum) to REMOVE as much base metal – mechanically &/or chemically - BEFORE putting PMs into solution – to then recover them in a refined form.

Please understand that I am not saying that you are wrong about being able to use AR to dissolve both base metal & PMs & come out with a refined PM with little or no loss in the end – I am just saying it not a very good suggestion to present it as a workable alternate method to refining for people on this forum – because like me – most of the people on this forum – have already been instructed to do just that – as the way to refine - & now they are trying to figure out – were is all my value going

Kurt

 

[Wyndham]

Thank you Harold for the indepth reply. I can readily see that the percentage of gold in plated or filled material compared to the base metal points to better methods than AR. Knowing these facts and the other methods available I can put this method aside but have learned much as to why it works.
In my business as a potter, I have learned many ways and processes to work with clay but I have chosen only a few that work best for the product I wish to create today. However, Knowing how other processes work allows me the opportunity to use those tools should the need arise. As my customer's taste changes over time, I can use my bag of tricks for a new direction if needed.
This forum is a roadmap that can't be found anywhere else on the net, thanks again Wyndham