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#1
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Gold refining in a nutshell.
This process involves a two-step acid dissolution using nitric acid and
aqua regia followed by reconstitution of gold. 1. Get all your gold together and figure out how much pure gold you have by weight. This may require melting a bar and having it assayed, but if you are pretty good at testing gold you can figure it out arithmetically. 2. Melt your gold in a crucible kiln and add 4 parts of copper to every part of pure gold. This is called "quartering." Once your copper/gold mixture is thoroughly melted and orange hot, empty your crucible using tongs and heat resistant gloves over a large barrel full of water to make copper/gold shot. Be careful not to drop the hot crucible in the water this can result in an explosion and injury. Use appropriate safety equipment including heavy aprons and welder type masks. 3. Empty the barrel and recover your shot. Place your copper/ gold shot in an industrial size stainless steel pot over a hot plate set at medium heat, if you have small quantity of shot you may use a large glass beaker instead. Add enough nitric acid to thoroughly cover the metal, approximately twice the height of the metal itself. This will cause immediate bubbling and dissolution of copper, silver and other metals resulting in a thick blue liquid. Copious fumes are being released so be sure you do this under a hood with excellent extraction or out in an open area where it is permitted. Use proper gas masks. Once the acid stops dissolving metal it needs to be replaced with fresh acid. Empty the old acid into a holding tank taking care not to empty out the gold material and replace it with new acid. Several "attacks" maybe needed until all that remains is a brownish powder, this is nearly pure gold, about .995 pure. 4. Following your last attack carefully rinse your gold powder until the acid is removed then slowly dry the material over a hot plate at a low temperature. Place the gold powder in a large beaker containing Aqua Regia (3 parts nitric acid to one part hydrochoric acid) over low heat, this is one of the only solvents strong enough to dissolve high grade gold. Lower grade golds cannot be dissolved this way because silver chlorides form and stop the process. That is why the two step process is required. 5. Once your gold is completely dissolved the aqua regia will turn a clear golden color. The aqua regia then needs to be neutralized by slowly adding "urea," an alkaline material which is available at feed stores. Do not add too much at once or a violent reaction will occur causing the liquid to spill. Once the addition of urea no longer cause the liquid to react, the acid has been neutralized. 6. To this golden liquid is added sodium bisulfite or ferrous sulphate which causes the gold to reconstitute from the liquid and precipitate to the bottom of the vessel. Remove the acid taking care not to spill any gold and rinse thoroughly until all acid is removed. It is wise to use a Buchner funnel with paper filter since small amounts of gold may be spilled. 7. Dry the gold and melt once again. You now have gold that is .999 pure or better. Dont throw out your leftover liquids, there is silver in that solution which may be recovered through processes beyond the scope of this note.=20 Big Moe in Miami |
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#2
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On Sun, 09 Oct 2005 16:55:23 GMT, "bigmoe"
wrote about gold refining in a nutshell. What kind of a nutshell? --=20 Marilee J. Layman |
#3
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On Sun, 09 Oct 2005 09:54:58 -0700, in =A4=07=F5 "bigmoe" =
wrote: This process involves a two-step acid dissolution using nitric acid and aqua regia followed by reconstitution of gold. Not bad as a synopsis, but people should do a little more research before relying only on this. A couple comments. Stainless steels are not all the same. I'd be reluctant to use a = stainless container for a nitric acid solution, as some stainless alloys won't hold= up to it, especially in the strengths used here, and in the presence of other = metallic ions, which might, under some circumstances, set up galvanic potentials = that could hasten corrosion of the stainless. I'd stick with lab grade glass,= like pyrex, or use an appropriate plastic like Nalgene or the like. =20 No mention is made of testing solutions to be sure all gold is recovered,= or to be absolutely sure that all acid is neutralized by the urea. Failure to = do that can result in loss of gold. The procedure described assumes a scrap of only gold or silver precious = metals, no platinum group metals. As described, the recovered gold will also = contain some or all of the platinum group metals that might have been in the = scrap. Additional steps are needed to seperate those metals to avoid = contamination of the recovered gold, and considering the value of some of the PGM metals, = it's worth doing. =20 Mention needs also to be made of required safety precautions. The acids = used and the fumes are not friendly to lungs or workshops. These materials = need to be used with considerable care. Interested folks may wish to delve into the I.Shor web site at http://shorinternational.com/contents.htm. There's a lot of good info on refining there, including, if you search deeply enough, pretty much full instructions for the whole detailed procedure for in-shop refining, = including procedures for refining silver and recovering platinum. They describe it= around their "sub zero" product, which replaces the nitric acid in the aqua = regia mix, for increased safety, and, I think, lower costs. But the procedure is = otherwise the same as if you're using the traditional acid mix. They sell many of = the needed chemicals and testing stuff too, as well as their well known = "Simplicity" system for refining, that greatly reduces the risks associated with the = acids used in the usual method. Hope that helps. Peter Rowe |
#4
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Why the copper? No mention of any flux to keep that copper from =
oxidizing=20 in the melt. Why no mention of the proper strength of Nitric acid? Too=20 strong acid causes your Gold to break apart into a powder that is = extremely=20 difficult to remove from the solution. Use Pyrex --- not stainless steel. In fact there are so many things wrong with this procedure that perhaps = the=20 proper subject line should have been "Gold refining from the nuthouse." In point of fact any alloy less than 990 fine in combined Gold and = Silver=20 can not be parted without the gold disintegrating with some of the Gold=20 particles so fine that they cannot be removed from suspension. = "Quartering"=20 is better known to the refining trade as "Inquarts" and the metal used is= =20 Silver. If there is 2 1/2 - 3 times more Silver than Gold in the = resulting=20 "shot", and if the "shot" is rolled to .010 inch thickness, and if 1.06 = s.g.=20 Nitric Acid is used (first heat the acid until vapor can be seen rising = from=20 it, then add the rolled alloy. If it does not immediately begin to = dissolve=20 then add 1.26 s.g. Nitric Acid a droop at a time until it does.) the base= =20 metals and Silver will quietly dissolve into the acid and the rolled = alloy=20 can be seen to shrink without breaking apart. When the action of the acid= =20 ceases, carefully pour off the solution into another beaker and add = enough=20 1.26 s.g. Nitric acid to cover the remaining metal and heat to just below= a=20 boil and hold there for 10 - 30 minutes. Then pour the acid into the = beaker=20 with the previous solution. Cover the remaining metal with distilled = water=20 and bring to a boil. This will remove most of the Silver Nitrate = remaining=20 in the Gold. Repeat the distilled water wash twice more. You can now=20 "anneal" the remaining Gold which will change it from a brownish-black,=20 amorphous mass to the familiar yellow of Gold. An experienced eye can = tell=20 the relative purity of the Gold by its color. After annealing the additional Aqua regia step can be done to recover = Fine=20 Gold of .999 or better fineness. As Peter so nicely puts it, anyone wanting to try their hand at refining= =20 Gold will be well ahead of the game by doing a lot more reading than a = post=20 to a newsgroup. --=20 Don Thompson Remmy sez, Count de Monet. Unless, of course, you are Baroque. "bigmoe" wrote in message=20 ... This process involves a two-step acid dissolution using nitric acid and aqua regia followed by reconstitution of gold. 1. Get all your gold together and figure out how much pure gold you have by weight. This may require melting a bar and having it assayed, but if you are pretty good at testing gold you can figure it out arithmetically. 2. Melt your gold in a crucible kiln and add 4 parts of copper to every part of pure gold. This is called "quartering." Once your copper/gold mixture is thoroughly melted and orange hot, empty your crucible using tongs and heat resistant gloves over a large barrel full of water to make copper/gold shot. Be careful not to drop the hot crucible in the water this can result in an explosion and injury. Use appropriate safety equipment including heavy aprons and welder type masks. 3. Empty the barrel and recover your shot. Place your copper/ gold shot in an industrial size stainless steel pot over a hot plate set at medium heat, if you have small quantity of shot you may use a large glass beaker instead. Add enough nitric acid to thoroughly cover the metal, approximately twice the height of the metal itself. This will cause immediate bubbling and dissolution of copper, silver and other metals resulting in a thick blue liquid. Copious fumes are being released so be sure you do this under a hood with excellent extraction or out in an open area where it is permitted. Use proper gas masks. Once the acid stops dissolving metal it needs to be replaced with fresh acid. Empty the old acid into a holding tank taking care not to empty out the gold material and replace it with new acid. Several "attacks" maybe needed until all that remains is a brownish powder, this is nearly pure gold, about .995 pure. 4. Following your last attack carefully rinse your gold powder until the acid is removed then slowly dry the material over a hot plate at a low temperature. Place the gold powder in a large beaker containing Aqua Regia (3 parts nitric acid to one part hydrochoric acid) over low heat, this is one of the only solvents strong enough to dissolve high grade gold. Lower grade golds cannot be dissolved this way because silver chlorides form and stop the process. That is why the two step process is required. 5. Once your gold is completely dissolved the aqua regia will turn a clear golden color. The aqua regia then needs to be neutralized by slowly adding "urea," an alkaline material which is available at feed stores. Do not add too much at once or a violent reaction will occur causing the liquid to spill. Once the addition of urea no longer cause the liquid to react, the acid has been neutralized. 6. To this golden liquid is added sodium bisulfite or ferrous sulphate which causes the gold to reconstitute from the liquid and precipitate to the bottom of the vessel. Remove the acid taking care not to spill any gold and rinse thoroughly until all acid is removed. It is wise to use a Buchner funnel with paper filter since small amounts of gold may be spilled. 7. Dry the gold and melt once again. You now have gold that is .999 pure or better. Dont throw out your leftover liquids, there is silver in that solution which may be recovered through processes beyond the scope of this note. Big Moe in Miami |
#5
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Gold refining in a nutshell.
I bought a Shor Simplicity outfit which works very well,with a good
technical back up service,although I found that it is not as inofensive as they make out. All is great until you come to precipitate the gold where the fumes are very smelly and pungent....not as described in the video. Does anyone have a suggestion as to what I can do about these fumes....as I dont want to fall out with my neighbours. I have built a cabinet with an extractor which works perfectly but produces out side a "mist" ,pungent and I imagine toxic. regards Jim Ladd Don T ha escrito: Why the copper? No mention of any flux to keep that copper from oxidizing in the melt. Why no mention of the proper strength of Nitric acid? Too strong acid causes your Gold to break apart into a powder that is extremely difficult to remove from the solution. Use Pyrex --- not stainless steel. In fact there are so many things wrong with this procedure that perhaps the proper subject line should have been "Gold refining from the nuthouse." In point of fact any alloy less than 990 fine in combined Gold and Silver can not be parted without the gold disintegrating with some of the Gold particles so fine that they cannot be removed from suspension. "Quartering" is better known to the refining trade as "Inquarts" and the metal used is Silver. If there is 2 1/2 - 3 times more Silver than Gold in the resulting "shot", and if the "shot" is rolled to .010 inch thickness, and if 1.06s.g. Nitric Acid is used (first heat the acid until vapor can be seen risingfrom it, then add the rolled alloy. If it does not immediately begin to dissolve then add 1.26 s.g. Nitric Acid a droop at a time until it does.) the base metals and Silver will quietly dissolve into the acid and the rolled alloy can be seen to shrink without breaking apart. When the action of the acid ceases, carefully pour off the solution into another beaker and add enough 1.26 s.g. Nitric acid to cover the remaining metal and heat to just below a boil and hold there for 10 - 30 minutes. Then pour the acid into the beaker with the previous solution. Cover the remaining metal with distilled water and bring to a boil. This will remove most of the Silver Nitrate remaining in the Gold. Repeat the distilled water wash twice more. You can now "anneal" the remaining Gold which will change it from a brownish-black, amorphous mass to the familiar yellow of Gold. An experienced eye can tell the relative purity of the Gold by its color. After annealing the additional Aqua regia step can be done to recover Fine Gold of .999 or better fineness. As Peter so nicely puts it, anyone wanting to try their hand at refining Gold will be well ahead of the game by doing a lot more reading than a post to a newsgroup. -- Don Thompson Remmy sez, Count de Monet. Unless, of course, you are Baroque. "bigmoe" wrote in message ... This process involves a two-step acid dissolution using nitric acid and aqua regia followed by reconstitution of gold. 1. Get all your gold together and figure out how much pure gold you have by weight. This may require melting a bar and having it assayed, but if you are pretty good at testing gold you can figure it out arithmetically. 2. Melt your gold in a crucible kiln and add 4 parts of copper to every part of pure gold. This is called "quartering." Once your copper/gold mixture is thoroughly melted and orange hot, empty your crucible using tongs and heat resistant gloves over a large barrel full of water to make copper/gold shot. Be careful not to drop the hot crucible in the water this can result in an explosion and injury. Use appropriate safety equipment including heavy aprons and welder type masks. 3. Empty the barrel and recover your shot. Place your copper/ gold shot in an industrial size stainless steel pot over a hot plate set at medium heat, if you have small quantity of shot you may use a large glass beaker instead. Add enough nitric acid to thoroughly cover the metal, approximately twice the height of the metal itself. This will cause immediate bubbling and dissolution of copper, silver and other metals resulting in a thick blue liquid. Copious fumes are being released so be sure you do this under a hood with excellent extraction or out in an open area where it is permitted. Use proper gas masks. Once the acid stops dissolving metal it needs to be replaced with fresh acid. Empty the old acid into a holding tank taking care not to empty out the gold material and replace it with new acid. Several "attacks" maybe needed until all that remains is a brownish powder, this is nearly pure gold, about .995 pure. 4. Following your last attack carefully rinse your gold powder until the acid is removed then slowly dry the material over a hot plate at a low temperature. Place the gold powder in a large beaker containing Aqua Regia (3 parts nitric acid to one part hydrochoric acid) over low heat, this is one of the only solvents strong enough to dissolve high grade gold. Lower grade golds cannot be dissolved this way because silver chlorides form and stop the process. That is why the two step process is required. 5. Once your gold is completely dissolved the aqua regia will turn a clear golden color. The aqua regia then needs to be neutralized by slowly adding "urea," an alkaline material which is available at feed stores. Do not add too much at once or a violent reaction will occur causing the liquid to spill. Once the addition of urea no longer cause the liquid to react, the acid has been neutralized. 6. To this golden liquid is added sodium bisulfite or ferrous sulphate which causes the gold to reconstitute from the liquid and precipitate to the bottom of the vessel. Remove the acid taking care not to spill any gold and rinse thoroughly until all acid is removed. It is wise to use a Buchner funnel with paper filter since small amounts of gold may be spilled. 7. Dry the gold and melt once again. You now have gold that is .999 pure or better. Dont throw out your leftover liquids, there is silver in that solution which may be recovered through processes beyond the scope of this note. Big Moe in Miami |
#6
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Gold refining in a nutshell.
Perhaps the best way to reduce the fumes is to dilute your precipitant and
add it very slowly to the mother liquor. This will generate fumes of lesser intensity and they will have a chance to dissipate before they become noisome to the neighbors. Also increasing the airflow through your cabinet and the height of the outside "stack" will help. -- Don Thompson Remmy sez, Count de Monet. Unless, of course, you are Baroque. wrote in message ... I bought a Shor Simplicity outfit which works very well,with a good technical back up service,although I found that it is not as inofensive as they make out. All is great until you come to precipitate the gold where the fumes are very smelly and pungent....not as described in the video. Does anyone have a suggestion as to what I can do about these fumes....as I dont want to fall out with my neighbours. I have built a cabinet with an extractor which works perfectly but produces out side a "mist" ,pungent and I imagine toxic. regards Jim Ladd Don T ha escrito: Why the copper? No mention of any flux to keep that copper from oxidizing in the melt. Why no mention of the proper strength of Nitric acid? Too strong acid causes your Gold to break apart into a powder that is extremely difficult to remove from the solution. Use Pyrex --- not stainless steel. In fact there are so many things wrong with this procedure that perhaps the proper subject line should have been "Gold refining from the nuthouse." In point of fact any alloy less than 990 fine in combined Gold and Silver can not be parted without the gold disintegrating with some of the Gold particles so fine that they cannot be removed from suspension. "Quartering" is better known to the refining trade as "Inquarts" and the metal used is Silver. If there is 2 1/2 - 3 times more Silver than Gold in the resulting "shot", and if the "shot" is rolled to .010 inch thickness, and if 1.06 s.g. Nitric Acid is used (first heat the acid until vapor can be seen rising from it, then add the rolled alloy. If it does not immediately begin to dissolve then add 1.26 s.g. Nitric Acid a droop at a time until it does.) the base metals and Silver will quietly dissolve into the acid and the rolled alloy can be seen to shrink without breaking apart. When the action of the acid ceases, carefully pour off the solution into another beaker and add enough 1.26 s.g. Nitric acid to cover the remaining metal and heat to just below a boil and hold there for 10 - 30 minutes. Then pour the acid into the beaker with the previous solution. Cover the remaining metal with distilled water and bring to a boil. This will remove most of the Silver Nitrate remaining in the Gold. Repeat the distilled water wash twice more. You can now "anneal" the remaining Gold which will change it from a brownish-black, amorphous mass to the familiar yellow of Gold. An experienced eye can tell the relative purity of the Gold by its color. After annealing the additional Aqua regia step can be done to recover Fine Gold of .999 or better fineness. As Peter so nicely puts it, anyone wanting to try their hand at refining Gold will be well ahead of the game by doing a lot more reading than a post to a newsgroup. -- Don Thompson Remmy sez, Count de Monet. Unless, of course, you are Baroque. "bigmoe" wrote in message ... This process involves a two-step acid dissolution using nitric acid and aqua regia followed by reconstitution of gold. 1. Get all your gold together and figure out how much pure gold you have by weight. This may require melting a bar and having it assayed, but if you are pretty good at testing gold you can figure it out arithmetically. 2. Melt your gold in a crucible kiln and add 4 parts of copper to every part of pure gold. This is called "quartering." Once your copper/gold mixture is thoroughly melted and orange hot, empty your crucible using tongs and heat resistant gloves over a large barrel full of water to make copper/gold shot. Be careful not to drop the hot crucible in the water this can result in an explosion and injury. Use appropriate safety equipment including heavy aprons and welder type masks. 3. Empty the barrel and recover your shot. Place your copper/ gold shot in an industrial size stainless steel pot over a hot plate set at medium heat, if you have small quantity of shot you may use a large glass beaker instead. Add enough nitric acid to thoroughly cover the metal, approximately twice the height of the metal itself. This will cause immediate bubbling and dissolution of copper, silver and other metals resulting in a thick blue liquid. Copious fumes are being released so be sure you do this under a hood with excellent extraction or out in an open area where it is permitted. Use proper gas masks. Once the acid stops dissolving metal it needs to be replaced with fresh acid. Empty the old acid into a holding tank taking care not to empty out the gold material and replace it with new acid. Several "attacks" maybe needed until all that remains is a brownish powder, this is nearly pure gold, about .995 pure. 4. Following your last attack carefully rinse your gold powder until the acid is removed then slowly dry the material over a hot plate at a low temperature. Place the gold powder in a large beaker containing Aqua Regia (3 parts nitric acid to one part hydrochoric acid) over low heat, this is one of the only solvents strong enough to dissolve high grade gold. Lower grade golds cannot be dissolved this way because silver chlorides form and stop the process. That is why the two step process is required. 5. Once your gold is completely dissolved the aqua regia will turn a clear golden color. The aqua regia then needs to be neutralized by slowly adding "urea," an alkaline material which is available at feed stores. Do not add too much at once or a violent reaction will occur causing the liquid to spill. Once the addition of urea no longer cause the liquid to react, the acid has been neutralized. 6. To this golden liquid is added sodium bisulfite or ferrous sulphate which causes the gold to reconstitute from the liquid and precipitate to the bottom of the vessel. Remove the acid taking care not to spill any gold and rinse thoroughly until all acid is removed. It is wise to use a Buchner funnel with paper filter since small amounts of gold may be spilled. 7. Dry the gold and melt once again. You now have gold that is .999 pure or better. Dont throw out your leftover liquids, there is silver in that solution which may be recovered through processes beyond the scope of this note. Big Moe in Miami |
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