# Gold refining secret from karat jewelry



## SilverNitrate (Feb 3, 2008)

Ok this noob is telling his secret. But I will be brief and explain more later on.

Say you have a lot of jewelry gold, teeth, and even electronic teeth.

And you use AR (aqua regia). 

My method is dissolve everything in AR, generally its diluted to 50% of the concentrated acids to keep down on the fumes. Leave it in the acids for at least 2 days. make sure nothing you use in your lab is made of metal--- only use plastic and glass. 

filter the solution thru a buchner funnel into a bucket. 

add in sodium hydroxide solution making sure all is dissolved (the solution should look purplish brownish, with no green. then let this set up for a day or two. Test by dipping in a piece of copper if it forms a layer, you need more hydroxide. other wise your pH meter should be well over 10.

Mix up some Caustic Syurp (aldose solution) this will make a dark fluff on the bottom (this is gold) there will still be gold dissolved in the solution.
stir this and wait another day 

Titrate by pouring in conc. HNO3, the acid will immediately drop out the gold. The resulting copper and other metals will relain dissolved in the solution. 

You sould get at least 99% of your gold processed with a purity I have consistently got it over 99% purity.

After you seperated and rinsed off your gold, that solution should be set aside in a bucket with an ingot of copper and closed up for at least a week. any other gold will be dropped out and collected later.

If you did this from karat jewelry, the sludge containing silver chloride and stones can be handled this way.---

Take that then mix it in a beaker with NaOH and heat for some hours (depending on how much) as to make the silver into oxide. until this a nearly dry mass. 
Take outside and pour into a metal pot along with about 1/4 vol of dry sugar mix it then set it a fire with a match! after this burns you'll have pure silver!
Now take all the contents and dissolve in HNO3 to seperate the stones. now you have a silver nitrate solution which you can turn back into silver at a later time (see one of my other posts on processing that silver using the caustic syurp)
The stones can now be placed into a poly-propylene beaker of HF ---(yes the very deadly hydro-fluoric acid) this will dissolve the glass and lab made stones leaving behind only the pristene diamonds. anything else left will be small white worthless stones.



Disclaimer to anyone. This is for informational use only as this my method as from experience. I am well versed in the chemicals I use and know that some items can cause death if not properly handled. Other chemicals can permanently damage items. some process can potentially be a fire or explosion hazard.


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## Harold_V (Feb 3, 2008)

SilverNitrate said:


> My method is dissolve everything in AR, generally its diluted to 50% of the concentrated acids to keep down on the fumes. Leave it in the acids for at least 2 days. make sure nothing you use in your lab is made of metal--- only use plastic and glass.


While that can be effective on gold alloys that are low in silver, it will not dissolve gold that has excessive silver in its makeup. Green or yellow gold would likely resist fully dissolving due to the layer of silver chloride that forms on the solid pieces. If they're thin enough, that isn't the case, but if you attempt to dissolve jewelry in its original form, it would most certainly be a problem for heavy cross sections. How are you addressing the porting that won't dissolve? 



> You sould get at least 99% of your gold processed with a purity I have consistently got it over 99% purity.


Could you please tell us how you are assaying your yields to ascertain the purity?



> some process can potentially be a fire or explosion hazard.


Yes, I agree, you are providing instructions that have the potential to be unnecessarily hazardous. 

Would you please advise us why your method would be used in lieu of accepted practice, which is normally free of the majority of the hazards one may be exposed to with your system?

A good example that should be avoided when possible is working with concentrated basic solutions. They have the potential to instantly blind a person should some get in one's eyes. I survived exposure to tech grade nitric in that fashion, with no further consequences than a few days of discomfort. That's a far cry from being blinded. 

Harold


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## SilverNitrate (Feb 4, 2008)

> While that can be effective on gold alloys that are low in silver, it will not dissolve gold that has excessive silver in its makeup. Green or yellow gold would likely resist fully dissolving due to the layer of silver chloride that forms on the solid pieces. If they're thin enough, that isn't the case, but if you attempt to dissolve jewelry in its original form, it would most certainly be a problem for heavy cross sections. How are you addressing the porting that won't dissolve?


silver chloride that is formed is semi-permeable meaning that with ample time the acids will leach out the gold... hence why it should be done over a period of days



> Could you please tell us how you are assaying your yields to ascertain the purity?


I do this mainly as a hobby, refining the jewelry gold, though I am a PM broker as well, I likes to make high karat metals either to sell on market or into other chemicals. 
When I sell gold I have to have it independently assayed and the lowest number I got is 99.19% and as high as 99.8% metal basis.



> Would you please advise us why your method would be used in lieu of accepted practice, which is normally free of the majority of the hazards one may be exposed to with your system?



Refining gold is a more so a skill where as one's technique may differ from another to attain similar results. I find that the way I perform the method has less enviromental impact than other methods using AR. True there are the hazards but its the least hazardous way I have found thus far. One should always wear resistant gloves, face shield, lab-coat, work under a fume hood, and work close to a source of running water. Never take safety for granted.

The step involving HF acid is only used for recovering and identifying diamonds.


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## Smitty (Feb 4, 2008)

For anyone that is considering using HF in their experiments, please be extra careful since a regular water wash will not cure HF exposure on skin. Exposure to HF because it contains Flourine will require an injection of Calcium done by a physician. 

You may want to invest 75 dollars in a diamond/moisanite tester. It's hard to test stones if they are too small using the tester also.

It's also nice to hear that there are other options used for processing.


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## Harold_V (Feb 4, 2008)

SilverNitrate said:


> silver chloride that is formed is semi-permeable meaning that with ample time the acids will leach out the gold... hence why it should be done over a period of days


Having refined gold for well over 20 years, using the inquartation and AR process, I found that once you form a layer of silver chloride on gold, it becomes impervious. There's a delicate balance where the gold and other metals go into solution before the impervious layer can form. It could very well be that your process doesn't allow it to form, although I can't imagine it is a function of time. I've boiled in AR, for hours, gold that is high in silver as I've described, and it won't dissolve, nor will the silver chloride break down. It simply forms a thick layer and all action ceases. 



> I do this mainly as a hobby, refining the jewelry gold, though I am a PM broker as well, I likes to make high karat metals either to sell on market or into other chemicals.
> 
> When I sell gold I have to have it independently assayed and the lowest number I got is 99.19% and as high as 99.8% metal basis.



Thanks for that. While the numbers aren't bad, you're below the industry standard (9995), which I would not find acceptable. Depending on the contaminants, and the use of the gold, it could prove to be troublesome, and in some cases, costly, for the user. There are far better techniques that more or less insure quality. Proper handling in those cases is essential as well.. Anyone can produce inferior quality from the best of procedures if they aren't vigilant in following good practice. 

I'm more than familiar with precipitating gold from dirty solutions. I processed bench filings by dissolving them directly in AR, although they received a hot nitric/water wash prior to dissolution. The quality of the gold that came from that process was never good. You can't expect clean gold when it's precipitated from dirty solutions. If for no other reason, drag down will contaminate it beyond an acceptable level, and often even prolonged washing in hot HCl won't improve it to an acceptable level. 



> Refining gold is a more so a skill where as one's technique may differ from another to attain similar results. I find that the way I perform the method has less enviromental impact than other methods using AR. True there are the hazards but its the least hazardous way I have found thus far. One should always wear resistant gloves, face shield, lab-coat, work under a fume hood, and work close to a source of running water. Never take safety for granted.


I certainly agree with your recommendations to wear protective gear, and to work in a fume hood. Still, some of the process you recommend are more trouble than using more commonly applied methods. None of them present any more hazards for the environment that those you propose, and are certainly much faster. Quality would be better, too. 

For example, starting with a few ounces of gold, I can inquart, dissolve base metals and have gold dissolved and evaporating in less than two hours. I did that routinely. When pressed, a small amount of gold (a few ounces) can be processed totally in less than 24 hours. 

When you have a large volume of material to handle, which I did, the idea if giving any of it the luxury of sitting for days while they quietly worked simply would be unreasonable. Still, I find your process interesting. 



> The step involving HF acid is only used for recovering and identifying diamonds.



There are certainly better methods that don't present the risk of handling HF. Remember, many of these guys are working with less than essential equipment. It's a good idea to refrain from making recommendations to use HF-----which can get most of these guys in trouble, which they may not recognize until the damage is done. Unlike nitric, it doesn't give you much warning, does it! :wink: 

Harold


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## Irons (Feb 4, 2008)

Smitty said:


> For anyone that is considering using HF in their experiments, please be extra careful since a regular water wash will not cure HF exposure on skin. Exposure to HF because it contains Flourine will require an injection of Calcium done by a physician.
> 
> You may want to invest 75 dollars in a diamond/moisanite tester. It's hard to test stones if they are too small using the tester also.
> 
> It's also nice to hear that there are other options used for processing.



HF will dissolve them too.


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## SilverNitrate (Feb 4, 2008)

> HF will dissolve them too.



generally any sizeable ruby emeralds or pearl would be removed beforehand. those teenie tiny diamonds that cheap jewelry have can be identified more quicky using HF. 
I know the dangers of using HF and do not endorse its use. The fumes given off is as deadly as H2S or cyanide. Only the most advanced should consider its use for processing diamonds.


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## SilverNitrate (Feb 4, 2008)

> Thanks for that. While the numbers aren't bad, you're below the industry standard (9995), which I would not find acceptable. Depending on the contaminants, and the use of the gold, it could prove to be troublesome, and in some cases, costly, for the user. There are far better techniques that more or less insure quality. Proper handling in those cases is essential as well.. Anyone can produce inferior quality from the best of procedures if they aren't vigilant in following good practice.



In order to get gold pass 9995 fine the electrolysis will do, and still there is the time element. 
Noone here has access to molten gold piped thru with chlorine gas (the commercial bulk process)


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## Harold_V (Feb 4, 2008)

SilverNitrate said:


> > Thanks for that. While the numbers aren't bad, you're below the industry standard (9995), which I would not find acceptable. Depending on the contaminants, and the use of the gold, it could prove to be troublesome, and in some cases, costly, for the user. There are far better techniques that more or less insure quality. Proper handling in those cases is essential as well.. Anyone can produce inferior quality from the best of procedures if they aren't vigilant in following good practice.
> 
> 
> 
> ...


Yes, the Miller process. It should be avoided, much the same as HF-----it is, really, beyond the scope of the hobby refiner. 

I routinely surpassed 9995 quality-----although I never claimed to achieve 9999. All done chemically. My gold would melt without a flux cover, showing no oxides. You may have seen this picture, which has been posted several times. 

Harold


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## Lou (Feb 4, 2008)

That's the Miller process if I remember correctly. 

Never done it personally, but I could easily set up for it. Well, maybe not, I don't know offhand what pressure my regulator will go to for chlorine and it will have to be significant to account for the density of liquid gold.

I often thought about using it, but I deemed in impractical for my small amounts of gold. Now if I were processing 400 oz at a time instead of 4, perhaps then I'd consider it.



Personally, I'd keep away from the stuff if I were you lot and didn't have the proper gloves, respirator, and hood or nice teflonware  Generally, if you work with dilute (10-20%) solutions it's fairly safe so long as you don't get any on you. The 70% and anhydrous HF are wicked nasty and fume just standing.


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## lazersteve (Feb 4, 2008)

Irons said:


> Title: Better hope there's no Emeralds, Rubies or Sapphires
> 
> Body:HF will dissolve them too.



Irons posting style is to include his title comment in his posts. 

Nitrate,

Your process seems to require quite a bit of back and forth with HNO3. I see no need to increase the amount of HNO3 or my exposure to it when processing gold. As a matter of a fact, I'm all for *never* using nitric acid in my gold processing if at all possible. The same goes double for me and HF. There are cheaper and more easily accessible ways to dissolve your gold scrap and still achieve 'fine' gold. 

Personally, I will not post any method or refining process that I can not endorse as useful to others. 

Steve


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## Irons (Feb 4, 2008)

I knew that.  I was just giving a poke about other precious stones that would.

Separating Diamonds from gangue is another fun hobby. 

I see plenty of tiny stones hereabouts. Too bad they're not worth much.

I was reading about a dead star recently that is mostly crystallized carbon. that would kill the market.


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## Lou (Feb 4, 2008)

I'm going to have to read that post subject more closely from now on my friend. Sorry Irons! I goofed--I figured you knew better anyways.


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## SilverNitrate (Feb 4, 2008)

I'm saying HF has nothing to do with the refining of gold. only to stain or dissolve non-diamonds after all the gold and silver has been processed.

an aquaregia made of HF / HNO3 will not work nearly as good as HCl / HNO3 ...have tried it and then had silica precititate to deal with in the end.


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## Irons (Feb 4, 2008)

Lou said:


> I'm going to have to read that post subject more closely from now on my friend. Sorry Irons! I goofed--I figured you knew better anyways.



Most of the time, I deserve it. :twisted:


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## rockhammer53 (Feb 26, 2008)

Hydrofloric Acid is VERY dangerous in any concentration. It burns throught the skin and seeks the calcium in the bones. We had 1 exposure in an industrial lab where a female tech was splashed with a 10% solution and recieved contact with less than 2 mL and can no longer use her right hand from the tissue and bone damage suffered. This is NASTY stuff and should be avoided at the hobby level ! This CANNOT be reversed... period ! This is a real danger to children and pets and in some states you can be held criminally liable for harming others with it ! YOU HAVE BEEN WARNED !!! :!: :!: :!:


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## Harold_V (Feb 26, 2008)

I'm at a loss to understand how hydrofluoric acid relates to refining precious metals, particularly gold. None of the processes I used require it. 

The warning is worth hearing, I have no quarrel with that. 

Harold


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## rockhammer53 (Feb 29, 2008)

In the last 18 years of precious metals refining and electrowinning / electroplating the only place where HF was ever used was an etchant for Ti on a ceramic substrate in a High Tech lab.

I agree with Harold that HF has no place in this forum for any process or formula.


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## Irons (Feb 29, 2008)

Harold_V said:


> I'm at a loss to understand how hydrofluoric acid relates to refining precious metals, particularly gold. None of the processes I used require it.
> 
> The warning is worth hearing, I have no quarrel with that.
> 
> Harold



You cannot believe how painful a chemical burn from 70% HF is. We had a worker that used to open the bunghole on drums and take a sniff to see what was inside. He did that with a 55 Gallon Drum of 70% HF and it nearly killed him on the spot. He spent weeks in the hospital.


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## Harold_V (Mar 1, 2008)

Very early in my learning curve, when I had less than an idea of the evilness of acids, I sniffed a container of HCl. Need I tell you that I learned a great deal from that experience? 

As the old saying goes, when a guy picks up a horseshoe, straight from the hot coals of the forge, "it doesn't take me all day to look at a horse shoe".

Harold


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## SilverNitrate (Mar 1, 2008)

In most cases it is nearly impossible to acquire HF due to it high toxicity. Most people may know it as the stuff vandals use to scribble on windows as it permanently frosts glass. 
Hencewise this frosting will work on most gemstones and leave diamonds more identifiable.


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## Harold_V (Mar 1, 2008)

SilverNitrate said:


> In most cases it is nearly impossible to acquire HF due to it high toxicity. Most people may know it as the stuff vandals use to scribble on windows as it permanently frosts glass.
> Hencewise this frosting will work on most gemstones and leave diamonds more identifiable.



*That's what diamond testers are for*. 

The idea of recommending the use of HF in that capacity is way beyond anything that should be posted on this forum, although I intend to leave it as a reference.  

Please do not lose sight of the fact that almost none of these guys work with a fume hood, and some don't have enough wisdom to wear proper protective gear. Suggesting they use of HF is akin to telling them to work with cyanide when they have no clue. 

Be careful, folks. It's easy to get injured working with these reagents, as you all, I'm sure, already know. 

Harold


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## AKDan (Mar 2, 2008)

Hoke even mentions the use of HF. On page 182 it is suggested as the method of removing sand, enamel, porcelain and glass from platinum filings or iridium powder.

Better to educate in the proper function of any device, substance or item rather than to make it a boogy man in the closet. The fools of the world will obtain and abuse what they will, no matter what the warning or advice. 

Those with a more legitamate uses will benefit more from the education than from the stop signs, and will obtain and use if there is a need anyway. I hear the same junk about guns all the time too. A tool is a tool, and the only difference is in the use.


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## OMG (Mar 2, 2008)

I agree with AkDan saying that everything is a tool. The only thing is that HF is an extremely dangerous tool, and you can probably come up with something so you don't have to use such a dangerous tool.


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## Harold_V (Mar 2, 2008)

AKDan said:


> Hoke even mentions the use of HF. On page 182 it is suggested as the method of removing sand, enamel, porcelain and glass from platinum filings or iridium powder.


Sadly, she also recommended tossing on a generous amount of gasoline when incinerating. I surely wouldn't support her with that recommendation, either. I have a lot of faith in her book, but keep in mind that it was written when few, if any, regulations prevented people from being stupid. 



> Better to educate in the proper function of any device, substance or item rather than to make it a boogy man in the closet. The fools of the world will obtain and abuse what they will, no matter what the warning or advice.


The very reason I intend to leave the post with the recommendation. Readers may become aware, but they will not get encouragement from those of us that understand the unnecessary dangers involved. I want evidence presented that those of us on the board that advise are advising against it. This isn't strictly about handing out information that may or may not be useful, it's about giving a recommendation that isn't necessary, and has a high risk of harm. 



> Those with a more legitamate uses will benefit more from the education than from the stop signs, and will obtain and use if there is a need anyway. I hear the same junk about guns all the time too. A tool is a tool, and the only difference is in the use.


I agree, but fools will interpret the suggestion as something that could benefit them in some way, get harmed, then attempt to hold everyone but themselves responsible. I refuse to place myself, or Noxx, in that position. I do not endorse any process that is high risk, and serves no useful purpose, particularly when there are alternate courses of action that offer no risks at all. We are not here to temp idiots, we're here to, hopefully, provide information that is practical and useful for those that enjoy recovering precious metals. Damned few, if any, need worry about a "method of removing sand, enamel, porcelain and glass from platinum filings or iridium powder" These are not elements that the vast majority will encounter, and few of them will deal with filings, anyway. I refined for well over 20 years, and used HF for one reason and one reason only------and that was a rarity. I used it to pickle platinum buttons, in a small platinum dish. It is safe to say that in all my years of refining, I used a grand total of a couple fluid ounces, and I refined on a regular basis, 7/24/365. 

We have to be a bit careful on this forum to not provide instructions that are obviously unnecessary----and can prove to be quite harmful. Working with HF is one of the things that we don't need, and should not promote. Those that feel they need it can go elsewhere for their knowledge. Here, they are advised to not use it. If they are child enough to not follow good and proper advice, I sure as hell don't want to advise them to use HF for any reason. I think I speak for at least one of the other moderators in that regard, and perhaps both of them. GSP has an attitude about HF such that he won't even mention it by name. He's a well educated and experienced refiner. There's a message in that for anyone with brains. 

Harold


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## Lou (Mar 2, 2008)

It's nasty stuff through and through, but it has its uses. 


A safer alternative to working with HF is to use ammonium bifluoride. It is a solid, if kept neutral it will not form any HF. You can form HF in situ by adding H2SO4.

The convenience here is that this can be dissolved into water, and then poured over whatever one wants to digest. Then one would add sulfuric acid until they see material dissolve. This eliminates the pouring of HF, or the dilution of concentrated HF (a very mobile liquid, easily sloshes about).


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## AKDan (Mar 2, 2008)

Thank you for the reply Harold, and in reality I agree with you and all of your reasoning with regard to this subject. Reading through the many posts throughout this board I find myself in wonder at some of the operations and tactics people are chosing to use. I am amazed that there are not more stories of illness, injury, or death with respect to some of these "OK, this is what I did" stories.

Lou, thank you for the follow-up and what seems to be a much safer alternative to producing, and working with a dangerous substance.


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## Platdigger (Mar 2, 2008)

So, is there an effective way to (kill) for lack of a better word, the hf after produced?
Randy


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## Lou (Mar 3, 2008)

Yes, calcium hydroxide. You will get CaF2 precipitate, pretty stable stuff. Just keep it away from acid.


Lou


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## Arcani (Mar 27, 2008)

I believe he said in the original post that the HF was just a way of testing diamonds(as dangerous as that my be). I would like to hear more on his GOLD refining technique,(WHICH DOES NOT INVOLVE HF)


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## Anonymous (Mar 27, 2008)

I would not use it to test gemstone in jewerly because even though it may not affect diamonds what about other jews? I would think that gold or pt jewerly would rarely have glass as the gems maybe amethis(sp) or other semi precious.


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## ghut (Apr 27, 2008)

There's a lot of gold jewelry containing CZ's. As a jeweler and active purchaser of old jewelry, I deal with these almost daily. The easiest solution we've found is seperate pieces with CZs and diamonds and refining them seperatly.

A problem I have a the moment is that we had a glass container with approx. 3 oz of gold mud dropped on the floor. We strained most of the glass out, but still have very small particles of glass in the unmelted mud. Other than using HF, are there any recommendations to separate the glass from the gold? I'm thinking maybe we should just melt the mud and refine. Would this solve the problem?


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## Irons (Apr 27, 2008)

Just dissolve it in HCl/Cl and re-precipitate it. The glass won't dissolve.

If you melt it, it will take that much longer to digest it and you will end up having to use AR.

The HCl doesn't have to be concentrated, in fact, above .5 Molar HCl, the solubility of Chlorine decreases. Heating it also drives off Chlorine.

This Winter I did tests on HCl/Cl and it even worked well at Minus 20 Centigrade.

Take The Gold powder and put it in 2 equal volumes of HCl, Add a few drops of Chlorine bleach to generate Chlorine. If you add too much bleach, the Chlorine will just boil off and be wasted. You can always add more HCl later.

I prefer using 1/3 strength HCl and adding just enough bleach to make the solution cloudy. When it goes clear again in several hours, I add a little bit more.

Don't do this indoors unless you have a fume hood.

lasersteve has a video on the process.


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## Lou (Apr 27, 2008)

Personally, I would just melt it with extra borax. The borax will melt and react with any glass, which will float to the top and can be skimmed off or preferably broken off the cool button.


I had something similar happen to me with platinum black and some glass that got into it (broken stirring rod) after spending about 20 minutes trying to pick out the little flakes of glass, I just decided to use ammonium bifluoride and some sulfuric acid to remove the glass, then dry the Pt. Worked like a charm!


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## goldsilverpro (Apr 27, 2008)

I'm sure it's contaminated from being on the floor. You need to re-refine it so there's no reason to melt it. Just dissolve it in minimum aqua regia, dilute 3 to 1, filter, and go from there.


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## ghut (May 2, 2008)

Thanks for all the suggestions/advice and great info. I did refine it without melting. Good results with a beautiful shinning 1.9ozt ingot. I lost a small amount


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## ghut (May 2, 2008)

Don't quite know what happened my last post posted while I was typing. I lost a small amount still on the floor somewhere, but was relieved with the results I finished with.


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