That may be because the gold didn't use the particulate as a neculation site because it occurred at the FeSo4 surface instead as an overall reaction in the solution. The trash would act as a seed crystal for the formation of gold clusters to occur on the surface.
the amazing impossible to filter clean solution!
- Thread starter cnbarr
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I'd be shocked if you get 15 g, but perhaps the color was stronger before all the filtration/dilution...
My guess as to the cloudiness is that you may have some tin in the mix, not much but some. If that's possible I'd suggest incinerating your gold powder and a good hydrochloric acid soak to remove any traces before redissolving.
I had a similar experience with what I believe was saturated lead chloride. It went straight through the filter and never cleared up. Then I remembered to add a few drops of H2SO4, a lot of white salt precipitated and suddenly I could filter it without problem.
Göran
Göran
, all the pins were pressed into the board, clean no solder on any them. I always incinerate as a pretreatment just incase there are any oils or organics.
I processed 15lbs of the same pins a few days prior, with no issues at all, and I always add a bit of H2SO4 to help clear up any possible lead.
@Lou, yes my original volume was much lower, about 500ml, it increased to almost 2000ml after 30+ filterings.
I processed 15lbs of the same pins a few days prior, with no issues at all, and I always add a bit of H2SO4 to help clear up any possible lead.
@Lou, yes my original volume was much lower, about 500ml, it increased to almost 2000ml after 30+ filterings.
Geo
Well-known member
looks like an insoluble chloride. actually, it looks like AgCl. is there the possibility of some cross contamination with silver? maybe the pins had a component that was silver or was plated with silver. once the silver goes through the AR solution, the AgCl will be so fine that it will pass through the finest filters until you get down to lab filters made to filter 1 micron or less.
I see that some people are guessing if there is Au in solution just by the color. I'm curious as to how that works when a lot of times doing ewaste we are working with very dirty solutions? I have a picture of a solution I literally just dropped and am waiting for it to settle so I wanted to see what everyone thinks about this solution. I know it's a little off topic but wanted to post the pic to this thread to see if the people who have commented on this would comment on my picture.
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Moose, to be honest I absolutely never judge gold content by the color, unless it is a very clean solution, but by that point I already know what I have!
Hey Geo, you were right! I took a 100ml sample to work today, and filtered it through a glass fiber filter, then digested the solids, and had it and the filtrate tested on the icp-oes. The digested solids were 285ppm silver and the solution held 122ppm silver!
The question is were did the silver come from and why didn't I see with the other two batches of the same pins I ran?
I don't know where it came from but it was there, the only thing I can figure is if there were some other pins mixed in with them that I overlooked.
Hey Geo, you were right! I took a 100ml sample to work today, and filtered it through a glass fiber filter, then digested the solids, and had it and the filtrate tested on the icp-oes. The digested solids were 285ppm silver and the solution held 122ppm silver!
The question is were did the silver come from and why didn't I see with the other two batches of the same pins I ran?
I don't know where it came from but it was there, the only thing I can figure is if there were some other pins mixed in with them that I overlooked.
Geo
Well-known member
well, it sounds like something residual. check the nitric bath that you digested the pins in. there may be a recoverable amount of silver in it.
freechemist
In Remembrance
To me, this is the key-sentence in this whole long thread, the most important word being "guessing". But I see no notion, like testing, SnCl2 and the like. Testing will show you, if there still are really values in the pictured remaining "amazing solution", and if it makes sense, therefore to continue working with it.
Even with a lot of dissolved base metals, the presence of gold (yellow) in the solution can usually be seen, if you look at it in the right way. With good lighting, the yellow color of dissolved gold can sometimes be seen at the very edges, where the surface of the solution meets the glass. In a clear glass beaker or white plastic bucket, I draw some solution up on the plastic or glass an inch or two with a stir rod. With good lighting, if gold is present, you will momentarily see a yellow streak that is fairly slow to drain back into the solution. Assuming no PGM's are present, about the only other common thing in solution that will be yellow is iron. However, iron in solution doesn't produce a yellow streak on the glass or plastic.
Believe it or not. It's always worked for me, but only as a quicky gross indicator, especially while I'm dropping gold. You still need stannous chloride testing to determine whether all the gold is 100% dropped.
Believe it or not. It's always worked for me, but only as a quicky gross indicator, especially while I'm dropping gold. You still need stannous chloride testing to determine whether all the gold is 100% dropped.
Thanks for the info Chris. It's always good to have those little tricks in the bag. I have noticed what you said though especially at the top of the solution where the AR meets the glass before dropping there is yellow and after it has faded to more of a green color. This is in AR solutions from ceramic cpus, not a clean AR solution.
Tyler
Tyler
