toothpick93
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Processing a bar of impure bar of gold
G'day SM
I'm looking at investing in a couple things to refine and sell, I have everything I need to refine just nothing to process so I'm looking a few scrap
places. I might make a separate post regarding another refining process I would like to do but for now this one is the main one I would like to know
the details for. So some guy is selling a 50.62 gram bar of a gold ingot which has been processed once but only to get a mixed alloy bar, he states it
contains Gold, Silver, Copper, Nickel and maybe a few others from Computer boards and military telecommunication electronics (which I know is a high
gold yield for military boards. The main 2 metals I would like to recover would be Gold and Silver of course and I can process the remaining later, I
have a furnace that can reach up to 1400 degrees Celcius which is not hot enough for nickel but I should be able to melt the far into beads for more
surface area.
If the melting goes well I should have heads of metal instead of a bar which I can then dissolve in Aqua Regia, I dont care about how long it takes.
from here I plan to go about selective precipitation to separate the gold from the solution and then the silver. How would I go about this to only
precipitate one at a time instead of forcing out everything from solution.
Questions:
Will everything from that alloy bar dissolve in Aqua Regia?
Will sodium bisulfite be the best method of extracting the gold?
What should the method be to extract silver if there is much to be recovered?
Anything else I should know?
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diddi
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there is a YT chanel called goldnscrap, from memory. they have some good ideas. if it is raw puta boards, dont expect too much gold. i have done a
few runs of e-waste and there is a lot of work for not much good stuff. most is copper which uses up buckets of nitric acid. hardly worth the loss
of chems for what you get to be honest. and there are some threads here as well.
Beginning construction of periodic table display
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ave369
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Not everything. Silver will not dissolve in aqua regia, instead it will turn into the insoluble silver chloride. Gold, copper and nickel will
dissolve. Silver is easily extracted from the insoluble residue; calcine it to remove chlorine.
The remaining stuff, a mixture of tetrachloroauric acid and chloride complexes of other metals, can be separated with fractional crystallization and
then reduced.
[Edited on 8-3-2016 by ave369]
Smells like ammonia....
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woelen
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The mixture of chloroauric acid and other metal's complexes need not be separated. Simply add the bisulfite to the acidic mix. Gold precipitates,
while the other metals like copper and nickel remain in solution.
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j_sum1
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You could also look up kadriver on these boards. He has introduced some novel methods for refining scrap using low-cost and low hazard OTC chemicals
and techniques. His YT channel (under a different name which I forget) has detailed step by step procedures to follow.
Recently I have been watching Cody's lab. He is part way through a series on refining from a variety of different grades. He demonstrates a number
of different procedures so that you can evaluate the effectiveness of each. Currently 6 vids in the series with more to come. Both gold and silver
discussed.
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toothpick93
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Thank you so much for all of your feed back 
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Sulaiman
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Just something to consider;
with facilities to recover scrap precious metals in bulk
why sell the scrap in small quantities rather than refine it ?
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toothpick93
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Also Will I be able to melt the ingot in the furnace even if the temperature is not hot enough for Nickel?
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