I have mixture of gold, silver, tin, lead and copper as iodides. It was made by adding iodide and SMB to solution after AR dissolving and messing up by adding aluminum. Aluminum was added after SMB precipitation failed. Adding potassium iodide will turn them into soluble coplex forms. How can I drop out the gold separately? vitamin c does not work good, adding hydroxide and heating coprecipitates oxides. Maybe I should add hydroxide alone and heat to precipitate gold and oxides, lead and tin will dissolve in excess hydroxide. I would have then copper oxide, silver oxide and gold as powder. Then simply adding weak acid like acetic should dissolve silver and copper leaving gold. Is that a good idea? Thanks in advance.
gold precip from iodide complex
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Ander, this is starting to sound like a dangerous mix of chemical's.
It does not seem dangerous to me- not as explosives. Iodide complexes are well known and stable. Solution that left after iodides precipitation contains chlorides, some nitrates, sulfates, iodides and aluminum, sodium, potassium. They are not explosive neither very harmful. Solid iodides are also safe, the problem is with processing not with their dangerous properties.
I do not use iodine, If I did I would not mix with nitrates, or aqua regia,
I am not sure, sounds like a desperate attempt to get metals from a solution, and mixing processes, to me that can get dangerous, unless you understand the chemistry of all reactions involved, with this mix, I do not,
you may understand chemistry better than I do? but to me it sounds like you may have gotten a little inventive, and it is usually best to stick with proven methods, unless we really understand these reactions, the fact you have lead and tin in aqua regia gives me a clue you, really dont have that understanding yet.
if value in solution, what about replacing values with zink, and roasting precipitant and starting fresh.
if values are in powders a good red hot inceneration, start over eliminating tin, lead, and as much base metals as possible as chloride,
incenerate powders again, to remove chloride's from powders and then go for remaining base metals with nitric.
then insolubles with aqua regia.
if you want more information of seperating these metals (like lead chloride) we can help with that.
my concern would be the waste solution and how to safely deal with it. maybe someone with more knowledge with iodine can help.
I am not sure, sounds like a desperate attempt to get metals from a solution, and mixing processes, to me that can get dangerous, unless you understand the chemistry of all reactions involved, with this mix, I do not,
you may understand chemistry better than I do? but to me it sounds like you may have gotten a little inventive, and it is usually best to stick with proven methods, unless we really understand these reactions, the fact you have lead and tin in aqua regia gives me a clue you, really dont have that understanding yet.
if value in solution, what about replacing values with zink, and roasting precipitant and starting fresh.
if values are in powders a good red hot inceneration, start over eliminating tin, lead, and as much base metals as possible as chloride,
incenerate powders again, to remove chloride's from powders and then go for remaining base metals with nitric.
then insolubles with aqua regia.
if you want more information of seperating these metals (like lead chloride) we can help with that.
my concern would be the waste solution and how to safely deal with it. maybe someone with more knowledge with iodine can help.
Iodine is safe in acidic solution. Lead, tin and silver are present due to unprecise decantation. Solution was diluted by 5 times from its original volume. so called insoluble salts precipitate very slowly from diluted solutions and are difficult to separate by filtration or decantation. Today I will take part of my mucky powder and precipitate it as oxides. I have nice centrifuge at work- fits 320ml liquid at once, attached info says its 480gs . So no waiting for settling down is needed, just 5 minutes for perfect separation. My problem is, as you might noticed, impatience. Saving couple of hours results as waste of couple of days.
(The mess was totally my fault. I took off a couple days to make some PMs recovery. So I dropped out metals with aluminum- but I was impatient and had no clue how to separate metals from waste liquid.) Yesterday I dissolved separated iodides in potassium iodide and precipitated oxides with potassium hydroxide- 1 hour heating and centrifuge. Today I tried to dissolve the oxide but it didn't, so I reduced it to metal powder. Tomorrow I will work with centrifuge again. Liquid after iodide precipitation was treated with potassium hydroxide to drop metals as oxides (I'm not sure what it was exactly- seems gold+ copper oxide) until aluminum hydroxide redissolved, then centrifuged to obtain desired mixture. Because of shortage of time leftover mixture was treated couple hours ago with ascorbic acid to redissolve some aluminum hydroxide that was extremally hard to get rid of, liquid was so viscous that 80g (calculated) couldnt separate it from gold in 10 minutes of centrifuging. So, yesterday I spent good 6 hours operating centrifuge. Tomorrow will be also a busy day. I hope I will handle that eventually.
Irons
Well-known member
ander said:
Saying when I worked for the Government: How come we always have time to do it over, but never enough time to do it right in the first place?
:mrgreen:
Finally I got my copper powder rinsed and ready for redissolving. I'm curious if i could use sodium persulfate to dissolve copper. Then gold shouldn't dissole due to lack of halogen ions. And the solution should have blue color in case of gold absence.
Black residue from hydroxide precipitation was dissolved in AR- traces of tin and some other stuff were filtered. Reduction with SMB partially failed another time, some precipitate formed but it was not gold. So I used oxalic acid- It seems that most of the starting material was copper, leftover solution was green and lot of black powder formed. I tried to melt obtained powder, but apparently it was some nasty mixture. Melting with flux gave very few tiny whitish beads. Most of the powder dissolved in flux. Another 'hard way' lesson- don't mess with tin, lead and aluminum.
Black residue from hydroxide precipitation was dissolved in AR- traces of tin and some other stuff were filtered. Reduction with SMB partially failed another time, some precipitate formed but it was not gold. So I used oxalic acid- It seems that most of the starting material was copper, leftover solution was green and lot of black powder formed. I tried to melt obtained powder, but apparently it was some nasty mixture. Melting with flux gave very few tiny whitish beads. Most of the powder dissolved in flux. Another 'hard way' lesson- don't mess with tin, lead and aluminum.
ander if you are serious, you need to quit being inventive, there are processes that took century's to develop they work well, the wheel is already round, we just need to use it. maybe once we understand how to use the round wheel we may be able to modify it, but trying to modify a wheel that took century's to develop without a good understanding of it can only lead towards failure, you have the brains for this, use them to learn standard proceedures, get sucsessful with them first, you will get further towards your goal.
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I can't add anything to that statement.butcher said:
I will never understand people that aspire to refine, but insist on trying everything they can think of when there are good and viable processes at their fingertips. I am particularly troubled by "clever" individuals (those that think they already know how to refine when they don't) that don't have a clue, and don't want one.
I have to assume, due in part to what my objective was, that a person often refines for more than a single reason. Mine was to accumulate a serious supply of precious metals, which I managed to do. I was not interested in changing the wheel, finding it sufficiently round. I concentrated my efforts on improving my quality, which, in turn, had a profound effect on cornering more customers. I stuck with tried and proven methods, and was handsomely rewarded for my efforts. Then I sold my wheel and retired.
Harold
we do appreciate you showing us how to get our wheels rolling Harold.
trouble is sometimes these hamster wheels in our head are always turning.
trouble is sometimes these hamster wheels in our head are always turning.
