AUH-R,
When I answered you last I could not see your pictures, that and the fact that I was not exactly sure what all you were talking about, just reading through the few posts.
The pictures add a whole new meaning.
It seems like I misunderstood a few things about what you were doing and how, you were doing them.
Now that I can see the pictures I have a little better Idea, I will not go back and try to correct my miss-understandings, but I will add just a few things I noticed from looking at the pictures.
What it looks like to me is you are working with Kovar iron based pins, these will include lead solder and the dreaded tin, HCl will attack these, and put them into solution, copper will not normally dissolve in just plain HCl without an oxidizer, but with heat and air from the atmosphere, or boiling some copper can be attacked. Gold will not be attacked, by HCl alone, or with HCl and a mild oxidizer like dilute hydrogen peroxide or oxygen from air. For copper to dissolve to much any extent needs an oxidizer like air, or oxygen which we normally add with H2O2 or an air pump.
Iron in solution as a chloride should not be boiled, heating is OK but, if boiled strongly we can precipitate the Iron out of solution as an oxide of iron, which will not dissolve in acids, I see what looks like iron oxides in your pictures above in that brown mud (probably iron copper and other metals, also in the ceramic dish with the foils where you say this is as close to incineration as you got.
I believe it is not the boiling hot solution that forms the red insoluble iron oxides, but it seems to me to be the bottom of the vessel where it comes into contact with the burner that cooks the iron out of solution forming the oxide (just speculation here).
This red rouge of iron will not dissolve very easily at all, even in strong acids or combinations of acids like aqua regia (which at time can be a good thing to help us separate our gold from the iron red rouge), other times we want to dissolve the iron away from our gold keeping the iron soluble (iron chloride in this case).
Looking at the picture of your foils in the ceramic dish, by the way the picture does not look anywhere near an incineration to me, you still have acidic chloride salts that have not been incinerated, the iron hydroxide’s and your gold foils, from the picture it just looks like you just dried these, before I would attempt an incineration on this type of material that had come from acidic chloride solutions, I would have rinsed the material and foils in a solution of sodium hydroxide to neutralize any remaining acid(or acidic metal salts), forming a salt water solution, and then rinse the powders very well to remove as much of the traces of chloride salts as I could, as gold chloride
The reason I would try to remove chlorides or any residual HCl is because at high temperatures we can cook off chlorine and HCl from the salts or powders, these gases can dissolve gold or platinum group metals and carry our values off in the fumes.
For an interesting read on this subject, look for the patient by Oskar Erhart (1939 I believe), the patient called process for converting gold, platinum, and other metals of the platinum group into a dissolved form, here he uses a heated jacket reactor, over a burner, with powdered or fine particles of gold and PGM on a shelf sieve above the HCl liquid level he also bubbles chlorine gas into the HCl solution the gases formed from HCl and chlorine pass through the valuable metals dissolve them into the fumes which are condensed back to liquid in the reflux condenser, dripping back through the powders and into the HCl / chlorine solution.
Iron in solution can look like copper in solution green to almost green/black, actually it is fairly easy to have a blackish concentrated solution of iron and copper in the same solution, but if this solution is diluted copper will begin to precipitate out as a whitish copper I chloride.
Iron can also make a pretty yellow solution that can look just like a gold chloride solution.
And as we know if we have a copper chloride solution and if we have elemental Iron it can push the copper back out of solution forming copper metal powders and an Iron chloride solution.
AUH-R,
Actually all in all it looks like you are doing pretty well.
The pictures painted a better picture than your description alone.
With your powders in the ceramic dish on your hot plate, wash them in a dilute hydroxide solution, and hot water washes, let it settle well before decanting the solution, with a suction bulb and pipette.
Through out this process I would leave powders in the dish, only removing liquids of soluble metal solution leaving any insoluble powders, so give them time to settle well.
You do have quite a bit of iron and copper to deal with in those powders, as well as tin and lead.
I would then dry the powders on low heat, raising the heat to high after they are dried, crush the powders after dried, keep them crushed until they finished roasting, use your propane torch and get them glowing red hot, stir the roast well to get plenty of oxygen to oxidize the metals which will also oxidize the tin,.
Before trying to recover your gold from them, we will want to remove the base metals.
Let them cool and give them good boil in HCl after the incineration (taking the solution up with water to remove tin and the soluble chloride metals.
I would try to dissolve as much of the base metals into solution as I could before I tried to put gold into solution,
If the HCl is colored heavily with metals continue with Hot HCl washes till it will pick up no more metal, be sure to let the insoluble powders settle well before you decant liquids.
You can dissolve the lead chloride in boiling hot water rinses.
Moving the decanted solutions to settling jars (any values carried or other insoluble base metal powder will settle in the jar and may need to be reprocessed.
Your lead chloride washes I would keep in a separate settling jar; the lead chloride will crystallize out as a white crystal after the water-cools, if the water is fairly clear after lead settles out the cool water can be returned to the powders and boiled again to pick up more lead (saving on water added to your waste stream).
After you can dissolve no more metals as a chloride solution, and your boiling hot water washes are picking up no more metals (judged by color or cooling lead crystals), your powders should be cleaned up enough to dissolve your gold, you can leave your gold in the ceramic dish, add HCl and small bleach additions to dissolve the gold, just barely warming your solution, after the gold goes into solution raise your heat a little to drive off free chlorine, when you have removed chlorine (here you can test for chlorine gas from the vapors of your solution, with a little ammonia in a lid of the bottle held in the fume of your solution, looking for that white smoke of ammonium chloride), once the chlorine is heated off you can shut off your stove cover your pot and let it settle out any insoluble salts, later decant your gold chloride solution through a filter into a clean jar for precipitating your gold.
When I answered you last I could not see your pictures, that and the fact that I was not exactly sure what all you were talking about, just reading through the few posts.
The pictures add a whole new meaning.
It seems like I misunderstood a few things about what you were doing and how, you were doing them.
Now that I can see the pictures I have a little better Idea, I will not go back and try to correct my miss-understandings, but I will add just a few things I noticed from looking at the pictures.
What it looks like to me is you are working with Kovar iron based pins, these will include lead solder and the dreaded tin, HCl will attack these, and put them into solution, copper will not normally dissolve in just plain HCl without an oxidizer, but with heat and air from the atmosphere, or boiling some copper can be attacked. Gold will not be attacked, by HCl alone, or with HCl and a mild oxidizer like dilute hydrogen peroxide or oxygen from air. For copper to dissolve to much any extent needs an oxidizer like air, or oxygen which we normally add with H2O2 or an air pump.
Iron in solution as a chloride should not be boiled, heating is OK but, if boiled strongly we can precipitate the Iron out of solution as an oxide of iron, which will not dissolve in acids, I see what looks like iron oxides in your pictures above in that brown mud (probably iron copper and other metals, also in the ceramic dish with the foils where you say this is as close to incineration as you got.
I believe it is not the boiling hot solution that forms the red insoluble iron oxides, but it seems to me to be the bottom of the vessel where it comes into contact with the burner that cooks the iron out of solution forming the oxide (just speculation here).
This red rouge of iron will not dissolve very easily at all, even in strong acids or combinations of acids like aqua regia (which at time can be a good thing to help us separate our gold from the iron red rouge), other times we want to dissolve the iron away from our gold keeping the iron soluble (iron chloride in this case).
Looking at the picture of your foils in the ceramic dish, by the way the picture does not look anywhere near an incineration to me, you still have acidic chloride salts that have not been incinerated, the iron hydroxide’s and your gold foils, from the picture it just looks like you just dried these, before I would attempt an incineration on this type of material that had come from acidic chloride solutions, I would have rinsed the material and foils in a solution of sodium hydroxide to neutralize any remaining acid(or acidic metal salts), forming a salt water solution, and then rinse the powders very well to remove as much of the traces of chloride salts as I could, as gold chloride
The reason I would try to remove chlorides or any residual HCl is because at high temperatures we can cook off chlorine and HCl from the salts or powders, these gases can dissolve gold or platinum group metals and carry our values off in the fumes.
For an interesting read on this subject, look for the patient by Oskar Erhart (1939 I believe), the patient called process for converting gold, platinum, and other metals of the platinum group into a dissolved form, here he uses a heated jacket reactor, over a burner, with powdered or fine particles of gold and PGM on a shelf sieve above the HCl liquid level he also bubbles chlorine gas into the HCl solution the gases formed from HCl and chlorine pass through the valuable metals dissolve them into the fumes which are condensed back to liquid in the reflux condenser, dripping back through the powders and into the HCl / chlorine solution.
Iron in solution can look like copper in solution green to almost green/black, actually it is fairly easy to have a blackish concentrated solution of iron and copper in the same solution, but if this solution is diluted copper will begin to precipitate out as a whitish copper I chloride.
Iron can also make a pretty yellow solution that can look just like a gold chloride solution.
And as we know if we have a copper chloride solution and if we have elemental Iron it can push the copper back out of solution forming copper metal powders and an Iron chloride solution.
AUH-R,
Actually all in all it looks like you are doing pretty well.
The pictures painted a better picture than your description alone.
With your powders in the ceramic dish on your hot plate, wash them in a dilute hydroxide solution, and hot water washes, let it settle well before decanting the solution, with a suction bulb and pipette.
Through out this process I would leave powders in the dish, only removing liquids of soluble metal solution leaving any insoluble powders, so give them time to settle well.
You do have quite a bit of iron and copper to deal with in those powders, as well as tin and lead.
I would then dry the powders on low heat, raising the heat to high after they are dried, crush the powders after dried, keep them crushed until they finished roasting, use your propane torch and get them glowing red hot, stir the roast well to get plenty of oxygen to oxidize the metals which will also oxidize the tin,.
Before trying to recover your gold from them, we will want to remove the base metals.
Let them cool and give them good boil in HCl after the incineration (taking the solution up with water to remove tin and the soluble chloride metals.
I would try to dissolve as much of the base metals into solution as I could before I tried to put gold into solution,
If the HCl is colored heavily with metals continue with Hot HCl washes till it will pick up no more metal, be sure to let the insoluble powders settle well before you decant liquids.
You can dissolve the lead chloride in boiling hot water rinses.
Moving the decanted solutions to settling jars (any values carried or other insoluble base metal powder will settle in the jar and may need to be reprocessed.
Your lead chloride washes I would keep in a separate settling jar; the lead chloride will crystallize out as a white crystal after the water-cools, if the water is fairly clear after lead settles out the cool water can be returned to the powders and boiled again to pick up more lead (saving on water added to your waste stream).
After you can dissolve no more metals as a chloride solution, and your boiling hot water washes are picking up no more metals (judged by color or cooling lead crystals), your powders should be cleaned up enough to dissolve your gold, you can leave your gold in the ceramic dish, add HCl and small bleach additions to dissolve the gold, just barely warming your solution, after the gold goes into solution raise your heat a little to drive off free chlorine, when you have removed chlorine (here you can test for chlorine gas from the vapors of your solution, with a little ammonia in a lid of the bottle held in the fume of your solution, looking for that white smoke of ammonium chloride), once the chlorine is heated off you can shut off your stove cover your pot and let it settle out any insoluble salts, later decant your gold chloride solution through a filter into a clean jar for precipitating your gold.
