# Refining placer gold and 10k-18K yellow gold



## Steven Crim (Jul 7, 2007)

I am a newbie doing my research before starting gold refining as a hobby. I am a new Forum member today and very happy to find and read so much info at one location. My goal is to refine my gold as pure as possible 999+. I have a few questions on my mind at this time.

1) With the inquartation method...if treating with nitric acid dissolves the silver, copper, zinc, etc, leaving only gold precipitate...why use AR?

2) With the inquartation method...I understand that allowing the gold particles to get too small can result in them staying suspended and lost while filtering or decanting etc.....but, if you allow the gold particles to stay larger, ie large (2-3mm) pellets to stay in their original honeycomb shape don't you risk the possibility of some of the non-gold metals being shielded by the gold and not being dissolved by nitric acid resulting in reduction of purity? How does one find the middle road for best possible purity?

**My thanks in advance to Harold and everyone for your help!! I will be getting the books by Ammen and Hokes soon. Steve


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## Harold_V (Jul 8, 2007)

Steven Crim said:


> I am a newbie doing my research before starting gold refining as a hobby. I am a new Forum member today and very happy to find and read so much info at one location. My goal is to refine my gold as pure as possible 999+. I have a few questions on my mind at this time.



Welcome to the forum, Steven. There's a good bunch of people here, quite knowledgeable and eager to learn and share information. You came to the right place. 



> 1) With the inquartation method...if treating with nitric acid dissolves the silver, copper, zinc, etc, leaving only gold precipitate...why use AR?



What you'll come to discover as you progress is that this system is very good at eliminating the bulk of base metals, but is not good at removing them entirely. The real value is that it removes silver to the point where AR will fully dissolve your gold, which, otherwise, can be troublesomes. It's also a great idea to include as little as possible in the way of base metals in your gold chloride solution, so dragdown is not such a problem. The initial digest addresses these issues, assuming you do it correctly. 

The preliminary treatment (nitric, after inquartation) will remove the majority of the low value metals, but you'll find that there's always a trace left behind. If your objective was to refine gold for re-alloying for manufacturing jewelry, and you were absolutely certain that you had not included iron or lead with your gold, it's conceivable you could use the gold after the first treatment, but it would be very risky, plus you'd have no way of recovering other values, such as platinum, and often even palladium. While each of them will follow the silver, you don't get a total separation. As I said, the treatment is very good at eliminating, but not totally. 

When you dissolve in AR, you put the values in solution, from which you can selectively precipitate specific elements, leaving the others behind in solution for later recovery. You would not be able to separate them otherwise, although there are other methods that don't lend themselves well to the hobby refiner. 

Your quest for 999+ gold will demand that you use AR, and you may come to find that a gold cell will be useful----although with diligence you can produce very acceptable gold without one. Don't expect 4 9's---but you should be able to reliably hit the industry standard of 9995----following good procedures and paying very careful attention to washing and melting practice. It's very easy to undo all your hard refining work when you melt your final product. You simply have to think "clean" at all times. 



> 2) With the inquartation method...I understand that allowing the gold particles to get too small can result in them staying suspended and lost while filtering or decanting etc.....but, if you allow the gold particles to stay larger, ie large (2-3mm) pellets to stay in their original honeycomb shape don't you risk the possibility of some of the non-gold metals being shielded by the gold and not being dissolved by nitric acid resulting in reduction of purity? How does one find the middle road for best possible purity?



Your concern is slightly misdirected. The size of particles you'll generate when you pour your inquarted gold in to shot (or cornflakes, as I like to call them) makes almost no difference, not as long as they're not too large. As they increase in size, it takes longer for the nitric to penetrate the alloy to the center, to eliminate all the base metal and silver. The concern about the gold being finely divided comes from improper inquartation, where you have the gold content too low. It's quite important to stay as close as you can to 25% (20/30% will usually function in an acceptable fashion), which will allow the gold to honeycomb to the point of full extraction of base metals without the gold reducing to tiny particles. That's where you get in trouble. You can also experience problems when you have some of the undesirable elements melted with your gold. Avoid tin like the plague-----it makes filtration almost impossible. 

When you inquart and pour your shot (cornflakes), you'll find that if you pour from a melting dish, you'll get cornflakes. If you pour from a nozzle (hole in the bottom of a dish) you'll get shot. Don't know why it makes a difference, but it does. 

Luck!

Harold


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## Joe (Nov 2, 2007)

I'm curious about something. Harold said, "avoid tin like the plague." I think he means that tin forms an awful insoluble white substance in nitric acid that has an oily appearance. At least that is what I have witnessed. 

I bring it up because it would be convenient to dissolve contacts still soldered to the PCB. Could the white insoluble substance that forms in nitric be metastannic acid? 

I've heard mention on here of a white insoluble substance being caught in filters. I wonder if it could be traces of metastannic acid. 

If so, it seems that the problems with dissolving solder in nitric might be avoided by treating the solder with hydrochloric acid. I don't know. I don't think I've ever tried putting PCB solder in HCL. It should attack the tin, but not the lead. 

I understand that it is hazardous environmentally and health wise to dissolve lead, but I'm following a thought. Thanks in advance for any responses. [/quote]


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## Harold_V (Nov 2, 2007)

I had an experience with tin that made things change for me. The problem I was addressing with tin is the snotty product that makes filtration difficult. Running tin through the nitric process seems to produce an abundance. 

I processed a lot of dental amalgam through the years. Part of my process, after retorting, was to roast the amalgam in an open container. I got the material to the mushy state, bordering on being completely molten. Stirring as it cooled provided small bits that were easily handled when it was cooled. The eutectic point of the amalgam is quite low, being an alloy of tin, silver and copper, so you're not talking about excessive heat in this instance. 

Bottom line is that once so heated, the solution that came from extracting the silver was easy to filter------the tin being oxidized by the roasting process. 

Your thoughts are very good. At some point in your processing, and it need not be before the application of nitric, if you'll incinerate the remaining solids after any given process (that's to kill acids, and to insure you've removed carbonaceous materials), you can then boil the material in HCL, which will dissolve the troublesome tin, or it's compound, making filtration of your gold chloride solution dead easy. It stands to reason that you'd wash the processed material well with tap water prior to dissolving the values with AR. 

Harold


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