# GOLD FILLED



## VAN (Mar 3, 2007)

IS THE BEST WAY TO REFINE GOLD FILL TO USE ACID OR AQUA REGIA?


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## Harold_V (Mar 4, 2007)

Aqua regia IS acid. It's a combination of HCL & HNO3.

If you don't have a copy, look for the book Refining Precious Metal Wastes, by C.M. Hoke. It's a wonderful book, published in the early '40's, as I recall, that will teach you to process gold wastes properly. Hoke was a chemist that wrote for folks (like us), that may not have a chemical background. I learned refining from that very book, back in the early 70's. 

For your information, Rio Grande (Jewelry) Supply, I think in New Mexico, used to sell a reprint of the book for a reasonable price. Don't know it they still do. 

Aqua regia isn't proper for dissolving yellow alloyed gold. The presence of silver makes dissolution difficult, if not impossible. You can literally boil heavy cross sections of 14K gold indefinitely in aqua regia and not dissolve the gold due to the impervious layer of silver chloride that encapsulates the gold, protecting it from further action. It's the presence of chlorine (HCL) that creates the problem. I've had minimal success with 10K, but it's a struggle. Much easier to inquart the stuff with silver and run it with nitric first. 

Processing karat gold is accomplished either by raising the gold content such that it represents no less than 90% of the alloy, and is then dissolved in aqua regia. The alternative is raising the base metal content until gold comprises only 25% of the alloy, at which time the base metal is dissolved with nitric acid. Once the base metal is removed, the gold will then dissolve easily in aqua regia for purification. 

If the items you have in your possession are thin enough, you can run them in nitric to eliminate the base metal, then go after the remains with aqua regia. It's likely that the little remaining silver won't be adequate to stop the gold from dissolving. If it is, you'll find a thin layer of gold that has a green appearance (that's the silver chloride) that refuses to dissolve. I feel that scenario is highly unlikely, however. It should work fine if you start with nitric and water, and pour off the solution before starting with aqua regia. Be sure to recover the silver from the solution. In this case, it's wise to do that with copper plates, for there may be lead present. Use the nitric sparingly---use only enough to do the job. Boiling helps get the mileage out of the acid. I used a gas fired hotplate for that purpose. You can do that outdoors if you don't have a fume hood. 

For your information, it's always a good idea to heat things to redness before starting the refining process. The presence of oil creates problems later-----and there's no better way to eliminate it than by incineration. It makes the stuff look ugly----but does no harm if all you intend to do is extract the values. 

Good luck! 

Harold


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## PRECIOUS METALS (Mar 4, 2007)

would it matter if you start burning the mucd while its still wet


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## VAN (Mar 4, 2007)

THANKS FOR THE INFO ILL TRY YOUR METHOD I KNEW AQUA WAS ACID BUT FIGURED IT WOULD WORK LOTS TO LEARN
VAN


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## VAN (Mar 4, 2007)

WHAT IS THE RECIPE WATER AND NITRIC? PARTS PER


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## Harold_V (Mar 5, 2007)

The amount isn't really important. When water is added, the hydronium ion assists the dissolution, so you actually get better mileage from the acid, or so I'm told. I'm not a chemist. 

My usual practice was to add about as much water as nitric. Too much just makes the action slower, but if you heat the work it won't make much difference. The one thing to learn is to control the amount of nitric you use. It's clearly a PITA when you use more than is required. A little experimenting will get you familiar so you'll have a sense of direction. 

Be careful with some of these metals. They are quite eager to react with nitric and can do so almost violently. Use a large beaker with a little solution, so there's enough room for the foaming without boiling over. If that does happen, depending on circumstances, wipe everything up with paper towels, then incinerate well. As long as you don't toss anything, you won't lose the gold, even if it boils over. It's a good idea to do your work in a confined area, with a surface that lends itself to being cleaned up under such occasions. I worked in a fume hood with a colorlith base----made it easy ------and safe. 

Harold


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## Anonymous (Mar 8, 2007)

Van, when I do gold filled I bought a coffee maker. The automatic kind. Then I cut the top off and trimmed it up a bit. The hot plate is built in and the temp seems to be constant. It has a nice pouring handle and a plastic lid! It also has a timer if you want to get real fancy.
MIDAS


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## lazersteve (Mar 8, 2007)

Great idea Midas!

Welcome aboard.

Please post a picture of your setup if you can.

Steve


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## VAN (Mar 8, 2007)

AFTER I BOIL THE JEWELRY WITH NITRIC ,THEN POUR OFF EXCESS ACID, THEN THE SLUDGE AT BOTTOM IS THE GOLD? SHOULD YOU WAIT AND LET THE SOLUTION SETTLE A LITTLE? THE SPOURED OFF SOLUTION IS THEN MOSTLY COPPER AND SOME SILVER. HOW DO YOU GET THE COPPER? ADD SALT FOR THE SILVER.
VAN


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## Harold_V (Mar 9, 2007)

VAN said:


> AFTER I BOIL THE JEWELRY WITH NITRIC ,THEN POUR OFF EXCESS ACID, THEN THE SLUDGE AT BOTTOM IS THE GOLD? SHOULD YOU WAIT AND LET THE SOLUTION SETTLE A LITTLE? THE SPOURED OFF SOLUTION IS THEN MOSTLY COPPER AND SOME SILVER. HOW DO YOU GET THE COPPER? ADD SALT FOR THE SILVER.
> VAN



I expect that you may get varied responses on this subject. Best I can offer is how I dealt with gold filled objects when I ran my refining business. 

After dissolving everything that will go into solution with nitric, the solution is taken up with water to dilute it well, then allowed to settle. Once the solution has settled, it is decanted, and a little salt introduced to the decanted solution to precipitate the silver as chloride. The solids that remain in the beaker should all be put in a filter and allowed to dry. Do not discard anything solid, especially if you find the material is purple in color. That's a sign of either silver chloride that has been exposed to light, or colloidal gold. Once dry, the filter and contents are incinerated until all the paper and resulting carbon is burned away completely. That can be accomplished in a discarded stainless frying pan, heated on a hotplate, then additional heat added with a torch when the pan is hot and the paper has quit burning. Heat until there is nothing left that burns. 

The remains are then placed in a beaker and washed in boiling HCL and water. That removes substances that make filtration of the gold chloride solution possible. If you skip this operation, there are times when it can take days for the chloride solution to get through the filter.

The HCL/water solution from this operation is discarded after testing. It would normally contain very little aside from traces of copper and iron. Aqua regia is then introduced to the beaker, dissolving the values. After evaporation, the solution is filtered, then the gold precipitated. You can expect one ounce of nitric and four ounces of HCL to dissolve a troy ounce of gold. Don't use any more than you need-----free nitric must be evaporated in order to recover the gold. 

When you refine chemically, never discard any filters. They should be incinerated and the resulting ash stored, for eventual processing for values. You'll recover considerable silver from chloride, plus traces of gold that are impossible to wash completely from the filters. Look at spent filters as a savings account. That's what they are. 

You can recover the copper from these solutions by introducing scrap steel, which replaces the copper in solution, and precipitates the copper as a fine mud. That is best carried out in a 5 gallon plastic bucket. 

Hope this helps. I know of no slick ways to process gold filled material. It's usually quite dirty stuff. 

Harold


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## VAN (Mar 10, 2007)

IS ANYONE ELSE RUNNING GOLD FILLED? IS IT WORTH TRYING ? I CAN GET SO MUCH OF IT IT ALMOST SEEMS LIKE IT WOULD BE WORTH IT.


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## Harold_V (Mar 11, 2007)

Typical gold filled material is far better than *anything* plated, and that includes extremely high quality wave guide materials. You can expect as great as 5% recovery from GF materials, and they're easy to process, although objects so made don't lend themselves to a stripping cell. You have to think like a refiner, not a gold recovery person, if you intend to process gold filled materials. 

If you want high quality gold, it should be dissolved and precipitated after all base metals are eliminated with a nitric and water boil. Also, because of the high risk of lead contamination, a trace of sulfuric acid should be introduced to the gold chloride before filtration, which will eliminate lead as lead sulfate. It is best added during the evaporation process. 

You likely are beginning to understand that it's a good idea to have a small fume hood and hot plate to run gold properly, although you can work under a window with an exhaust fan. I got by that way for a short while before building my first fume hood. 

Harold


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## lazersteve (Mar 11, 2007)

Hello Harold,

Could you write a short post on how to design a fume hood for the forum? I've been wanting to build one but have not done the research to build one. It would be a great safety contribution to the forum.


Steve


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## Noxx (Mar 11, 2007)

Yes, me too I would like to have some infos


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## socorban (Mar 11, 2007)

To my understanding there just exhuast hoods, like over your stove.

Unless there is a special fan you can get that will last longer being subject to acidic fumes the "hood" is a "hood" I use one in my basement were i use my cell. I just blocked up the outer window and installed a exhaust hood from lowes, it has served me very well for over 6 months and still running strong. No fumes and no oder when its runnin, of course you dont want a cheapo, i got a hefty more industrial style one but there all the same concept.

Hood, ventalation pipe to an outside source i.e. window or something.


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## Harold_V (Mar 11, 2007)

I'll post a picture of the last hood I built, and provide some details---but it may take a couple days. None of the pics of my refining days and lab are digital, so they'll have to be scanned and sized. I'm up to my ears in a house building project and don't have a lot of free time right now. Not to worry----I'll get it done. Just be patient. 

A conventional kitchen range hood is the wrong approach. It not only won't resist the acids you'll work with, it also allows fumes to escape into the environment where you work. A fume hood doesn't. You don't work under it, you work inside it. Everything goes up the stack, it has no choice. The range hood will work fine for limited use, but when you start refining, your hood must stand up to some pretty serious acid fumes---like when you're evaporating solutions, or even when you're dissolving your gold. Further, it should be filtered, so you can recover traces that end up in the exhaust stream. I had a routine of cleaning my hood every other year and always recovered at least 8 ounces of gold when I did. I'll talk more about that, and filters, when I post. 

The biggest problem you're going to face is finding a suitable material. Asbestos was still available to some degree when I built my equipment, so I didn't have any trouble finding acid and heat resistant board. Fact is, I was given a large stack of board that measured 1¼" thick, 18" wide, and 6 feet long. I used it in sections to form the sides of the hood. 

The chance of finding asbestos isn't good today---so someone should do some research to see what's out there that could be used for the intended purpose. It need not be thick-----3/4" material would suffice. 

Harold


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## lazersteve (Mar 11, 2007)

Harold,

Thank you for sharing this invaluable knowledge with us!

Take your time preparing the post. I'll do the necessary reasearch on the material you mention.


Steve


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## Anonymous (Mar 11, 2007)

I built a hood out of plexi glass and a small plastic fan. When the run off is over Ill post alot of pics on different items.
Midas


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## Noxx (Mar 11, 2007)

Hellos Midas,
Thank You for your participation. I will probably build my own when you will put pîctures.


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## Anonymous (Mar 11, 2007)

I'm not near as smart as Harold ,but I built a hood from plexi glass. I built a box{outa plexi} using brass or steel corner hinges the long ones drilled holes used a rivet gun then completely coated the exposed metal with silicon tube groute. then cut round hole used dryer exhaust couplers at hardware and dryer exhaust hose siliconed everything to be air tight as possible and made a front door there you go when I have more time Ill upload a pic My speeling is terrible.
Midas


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## VAN (Mar 11, 2007)

I just started the nitric in a crock pot and when I added the metal ALL HELL broke loose!!!!!hahahaha big gold colored flakes were boiling over everywhere luckily i did it outside. actually i hope that was gold flakes coz if so im a very happy man. But in reality there can't be that much gold from them,also my acid quit boiling and i can see the bracletts in there . the color of the acid turned a beautiful torquoise color.what do i need to do other than find another HOBBY!!!!!!!!!


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## Noxx (Mar 11, 2007)

Lol you're lucky... Me too yesterday my nitric acid eated my plastic bottle and I lost it all. Luckily, I did it outside.


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## VAN (Mar 11, 2007)

What are the gold colored flakes my acid test kit wouldn't eat it the 14k did but the 10k didn't. The 14k ate it but turned black HMMMMMM sounds like gold but it couldn.t be I only pay 20.00 a lb for it


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## VAN (Mar 11, 2007)

I ended up with the jewelry NOT dissolving and about 2" of green white gooooo at the bottom of my crock pot. Ill try again tomorrow. This time I won't put as much jewelry in the pot!!!!! AND TRY GOING SLOWER.aLL IN ALL ANOTHER GOOD DAY AT THE office.
vAN


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## Noxx (Mar 11, 2007)

You ended up with an insoluble salt right ?
It is cause mainly by too much silver in the solution. If you tried dissolving jewelry that contains silver, It may hide you gold and you won't be able to precipitate it all.


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## VAN (Mar 11, 2007)

I don't know what it is: white green goooo. The jewelry never dissolved so I can't imagine there could be that much silver in there. Might be anyway will try tomorrow. New mixture. Its so damn cold here could be the reason,my sulfuric didn't dissolve the sodium nitrte so I dissolved it in water, then added it to the mix thats when the poop hit the fan boil over opps. Then I added more water and sulfuric and it did boil and fizz for about an hour then quit AND SO DID I!!!!!!!
Van


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## Noxx (Mar 11, 2007)

Lol. Try soaking your jewelry in nitric acid before putting it in Aqua Regia. Should solve problem.


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## VAN (Mar 11, 2007)

I was boiling in nitric acid. but not much boiling going on at one point it was fizzing pretty good then quit. NOW I just went back out to shut the lights off checked the acid to see if it was some kind of silver and the white green goooo was GONE!!!!! What the .... is going on what should I do next ? I think Ill boil the acid till evaporated then make a new batch and start over whata ya think?


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## Noxx (Mar 11, 2007)

Why not just pouring the acid off ?


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## VAN (Mar 11, 2007)

Because it quit fizzing that's why I quit. So it must have run out of kick. It didn't reduce the jewelry either.


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## NaNO3 (Mar 11, 2007)

Van
Go back and read this topic.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=63
Read what Harold_V wrote.


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## VAN (Mar 11, 2007)

I did and tried to follow it to a tee, but had a break down somewhere. This is not something Ill learn in one day or by just reading. DOING it will be the best and unfortunately I haven't done enough so Ill have to keep banging away. Not to be proud but I'm a quick study when the bebe finely rolls in the hole! Thats why I read almost every post, but I think the main reason things went screwy its so damn cold. My acid formed crystals overnight and so then I just added and added till it fizzed duh I should start over and go slower. Thanks for your concerns everyone! DON'T GIVE UP ON ME YET!!!!!!!
Van
ps keep giving me that valued info.


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## Noxx (Mar 11, 2007)

Of course we will !


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## VAN (Mar 12, 2007)

Todd doesn't live there anymore and don't know where he moved his biz! will keep looking. Goota be a way for you canucks to have as much fun as Im having.hahahaha
hope that's not a derogatory term up there!!!!! seeing how Im a big AV'S FAN!!!!!!


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## Harold_V (Mar 12, 2007)

VAN said:


> My acid formed crystals overnight and so then I just added and added till it fizzed duh I should start over and go slower.



You're experiencing what happens when you try to work without the aid of supplemental heat. Chemical reactions always work faster with temperature, plus you get much better use from the acids involved. 

If you're trying to dissolve base metals without heating the solutions, it will be a long, hard process. It will work, just not as fast, and certainly not as well. The crystals you spoke of will go back into solution upon heating and adding a little water. It's normal for them to grow from saturated solutions as they cool. 

I realize I've harped on things quite a bit, but the things I have to say are exactly the things you're going to have to come to terms with if you intend to refine, or extract, precious metals. 

I started out in a garage, working under a window with a fan pushing fumes outside. It was better than nothing, but not by much. You simply must have a place to handle acids safely, or consider your hobby one that is restricted to the warm months alone. You can keep it relatively simple, but it's almost impossible to work without a hood of sorts, and a heat source to assist in the reactions. It may look overwhelming at first, but you build the needed things one at a time-----and let the profits from refining pay the bill. Worked for me. 

Harold


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## VAN (Mar 12, 2007)

well enough of this cold weather reclaiming Im going back in the house and drink lemonade till spring thats about JUNE here that gives me 5 months to play golf.fish and reclaim gold I NEED TO MOVE!!!!!!!!


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