kadriver
Well-known member
Here is a new video that I just completed:
https://youtu.be/8i2KXu1LhvA
Thanks for looking!
kadriver
https://youtu.be/8i2KXu1LhvA
Thanks for looking!
kadriver
goldsilverpro said:Excellent, Kevin!
I do have a couple of things, though.
(1) Ice vs dilution to drop AgCl. I've always felt that the ice method isn't nearly as efficient and I think you proved this in your video. I noticed that, when adding the ice to the 2nd AR, you still got a lot of AgCl dropping. Had you diluted the AR with 3 times water (instead of using the ice), in the 1st AR, you would have had no AgCl dropping in the 2nd AR, since it was all filtered out the 1st time.
Ice would drop most of the AgCl but, if the solution is allowed to warm, at all, even a few degrees, before it all goes through the filter, it will tend to re-dissolve (re-stabilize itself). Then, any rinsing dilutes the solution and causes the AgCl to re-precipitate, thereby contaminating the gold. Think about it. Before filtering, if the chilled solution is allowed to warm, you are essentially back to square one.
If you do use ice, I would use enough to get it down to about 33F and hold it there for awhile, Use the vac filter so it will suck through fast. It could help to freeze the funnel beforehand if it's made of porcelain.
Also, 3X dilution tends to take the power out of HNO3 that is present. Had you diluted and filtered the 1st AR, I would bet that the ferrous sulfate drop would have been trouble free. There are limits to this, of course.
(2) What's this about a brown stain when testing Au with stannous chloride? I've been doing this all my life and, when Au was present, the color always ranged from light purple to a very dark purple (essentially black), depending on the Au content - never brown, never, not with Au. The problem with brown is that other metals can also give brown. I think people call this a false positive although I never understood why - it's either purple or it isn't. I should mention that, while working with AR, I usually made up a fresh solution of stannous chloride, first thing, each morning - 1g stannous chloride, 15ml HCl, 15ml water - took only a couple of minutes to make it. I bought a 1/4 pound (113g) of stannous chloride crystals on eBay for about $11. I think the ad is still there but the guy went up a couple of $'s. I've never used tin solder to make it and maybe that could be the difference. When you tested the stannous chloride with the known gold solution, the color didn't look right to me.
goldsilverpro said:Excellent, Kevin!
I do have a couple of things, though.
(2) What's this about a brown stain when testing Au with stannous chloride? I've been doing this all my life and, when Au was present, the color always ranged from light purple to a very dark purple (essentially black), depending on the Au content - never brown, never, not with Au. The problem with brown is that other metals can also give brown. I think people call this a false positive although I never understood why - it's either purple or it isn't. I should mention that, while working with AR, I usually made up a fresh solution of stannous chloride, first thing, each morning - 1g stannous chloride, 15ml HCl, 15ml water - took only a couple of minutes to make it. I bought a 1/4 pound (113g) of stannous chloride crystals on eBay for about $11. I think the ad is still there but the guy went up a couple of $'s. I've never used tin solder to make it and maybe that could be the difference. When you tested the stannous chloride with the known gold solution, the color didn't look right to me.
Barren Realms 007 said:I would be a more precise in the use of the SMB you are using. Since you have an approximate weight of the gold you are recovering you can weigh out your SMB and dissolve it in water then add it to your solution. Rather than just dumping spoon fulls of SMB into your solution. I would have to say that the color from the stannous test was from the use of so much SMB.
Over all I would say a good production on the video.
Palladium said:Two questions. Are you using a hcl wash after the 2nd drop? Are you using two filter papers in the buchner?
kadriver said:Barren Realms 007 said:I would be a more precise in the use of the SMB you are using. Since you have an approximate weight of the gold you are recovering you can weigh out your SMB and dissolve it in water then add it to your solution. Rather than just dumping spoon fulls of SMB into your solution. I would have to say that the color from the stannous test was from the use of so much SMB.
Over all I would say a good production on the video.
Barren,
I'm not a chemist in any sense, I wouldn't know the "P" block from the "S" block except for watching a few videos on Khan Academy. How would one go about calculating the amount of SMB to use if the approximate quantity of pure gold yield is known?
Can you show an example please?
Thanks
kadriver
goldsilverpro said:Kevin,
The only disadvantage of 3X dilution I can think of is that there is more waste solution. However, the advantages of dilution greatly outweigh this, in my experience - Easier drops - Silver (as chloride) almost totally eliminated at the 1st filtering.
g_axelsson said:To avoid adding too much nitric I add less than the calculated amount at the beginning, then when I have dissolved most gold, approximately 90%, I let the reaction go to completion and pour off the gold chloride. Then I add a bit more HCl and small amounts of nitric. As the volume is smaller and the acids stronger it's easier to dissolve the last part without adding too much nitric.
Göran
Lou said:Or just rinse the silver chloride out with strong HCl to complex the silver and any copper.
Nice thing about the ammonia water rinse is you can see any copper go, but that copper is only going to go if it's copper (II), not copper (I) which is what most of the copper contaminant is. Use strong HCl and you get the copper and the silver removed.
I wrote a post about that rinse somewhere...
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