RajaMohsin
Well-known member
Okay sir i will try this
Stannous chloride Colors?
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RajaMohsin, I've looked at your pictures of your stannous tests, and they don't look like positive tests for gold to me.
When gold reacts with stannous chloride, it produces a distinctive purple color. It even has a name - Purple of Cassius. It can be very dark in concentrated gold solutions, but it is still purple. If it is too black to tell, the concentrated solution can be diluted, and the test made again.
But your tests look brown to me. This is a common reaction when a solution has copper dissolved in it, and SMB is used to precipitate gold. It is called a false positive because the dark color can be confused with the dark purple of a concentrated gold solution.
You can try to dilute your solution and try the stannous test again. You're looking for a purple color, not brown,
I wish I could be more encouraging, but I don't think you have a lot of gold there.
Dave
When gold reacts with stannous chloride, it produces a distinctive purple color. It even has a name - Purple of Cassius. It can be very dark in concentrated gold solutions, but it is still purple. If it is too black to tell, the concentrated solution can be diluted, and the test made again.
But your tests look brown to me. This is a common reaction when a solution has copper dissolved in it, and SMB is used to precipitate gold. It is called a false positive because the dark color can be confused with the dark purple of a concentrated gold solution.
You can try to dilute your solution and try the stannous test again. You're looking for a purple color, not brown,
I wish I could be more encouraging, but I don't think you have a lot of gold there.
Dave
Did you actually see the XRF result that said 40-60% Gold or was this the XRF belonging to the seller?
I have had customers bring material looking just like what you have into the refinery for us to melt and sample. The stuff looks like gold but it smoked badly when melting and it contained no precious metals on assay. We learned to test a small sample of the powder before melting with nitric acid. That is a quick indicator of whether or not it is gold.
I fear your grandfather was fooled by an XRF that was set to read gold where there was no gold. There are many scams in Africa, sad but true.
I have had customers bring material looking just like what you have into the refinery for us to melt and sample. The stuff looks like gold but it smoked badly when melting and it contained no precious metals on assay. We learned to test a small sample of the powder before melting with nitric acid. That is a quick indicator of whether or not it is gold.
I fear your grandfather was fooled by an XRF that was set to read gold where there was no gold. There are many scams in Africa, sad but true.
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- Oct 26, 2020
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Good morning to all of You guys
Have a Bless day.
Sometimes it has been seen that some peoples or some web sites, sell a supposed gold powder.
The seller puts a little bit of gold powder.
very minimum ,Just enough so that the xrf machines can read that small amount of gold powder.
But in reality everything they sell you is not gold.
Have a Bless day.
Sometimes it has been seen that some peoples or some web sites, sell a supposed gold powder.
The seller puts a little bit of gold powder.
very minimum ,Just enough so that the xrf machines can read that small amount of gold powder.
But in reality everything they sell you is not gold.
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RajaMohsin
Well-known member
I check in xrf the gold was show in xrf testing not before buy check now i check all dust powder in xrf the gold was show 50 60 percent and i put some dust in nitric end the end black powder is remaing now black powder was not dissolving in nitric
- Joined
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I don't know the amount of gold powder in the material you bought.
many peoples don’t trust xrf machines.
I’m one of them.
That black powder that You have after the
cleaning the material with Nitric acid.
You need to
Dissolve it the Black powder with aqua regia
to see if it is gold or Not.
grab the black powder,put it in a beaker
wash it with hot water few times.
to get rid of any acid and some mud or whatever is in there.
decant the water.
add Aqua Regia to it.
AR is HCL + Nitric acid.
(please use googles and rubber gloves
for your own safety).
First add HCL to the black powder in the beaker.
how many mls should be add it?.
depend on the amount of powder you have in the beaker
just cover all the material with HCL.
then add Nitric acid ,one drop of Nitric acid at the time.
until You see that the powder is dissolve it in the solution.
(of course if it is gold powder).
test it with fresh made Stannous Chloride.
testing with Stannous Chloride is the most important part.
because it will show You if there is gold in the solution.
if it is positive.
You now can Denox the solution with Sulfamic acid if You have it.
or You can use Urea
Urea is more easily available in many countries than Sulfamic acid.
Then filter the solution out
now the solution is ready for precipitating the gold with SMB or with Iron Sulfate.
many peoples don’t trust xrf machines.
I’m one of them.
That black powder that You have after the
cleaning the material with Nitric acid.
You need to
Dissolve it the Black powder with aqua regia
to see if it is gold or Not.
grab the black powder,put it in a beaker
wash it with hot water few times.
to get rid of any acid and some mud or whatever is in there.
decant the water.
add Aqua Regia to it.
AR is HCL + Nitric acid.
(please use googles and rubber gloves
for your own safety).
First add HCL to the black powder in the beaker.
how many mls should be add it?.
depend on the amount of powder you have in the beaker
just cover all the material with HCL.
then add Nitric acid ,one drop of Nitric acid at the time.
until You see that the powder is dissolve it in the solution.
(of course if it is gold powder).
test it with fresh made Stannous Chloride.
testing with Stannous Chloride is the most important part.
because it will show You if there is gold in the solution.
if it is positive.
You now can Denox the solution with Sulfamic acid if You have it.
or You can use Urea
Urea is more easily available in many countries than Sulfamic acid.
Then filter the solution out
now the solution is ready for precipitating the gold with SMB or with Iron Sulfate.
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ragood
Member
The attached picture shows a stannous chloride test of my solution after dropping the gold with SMB. The color looks brown to me. I remember it turning orange immediately and then turning brown as shown in the picture.
Do I have platinum in my solution? I refined some old white gold rings in this batch. I read some white gold contains platinum.
Thanks.
Do I have platinum in my solution? I refined some old white gold rings in this batch. I read some white gold contains platinum.
Thanks.
Attachments
That is why I prefer testing on paper. The gold stain on paper will obliterate the Platinum stain if there is still gold in solution. On a spoon or spot plate, if there is still a small amount of gold it gets dark and it is often difficult to see in some solutions. So you may have other PM's but that may be gold as well.
ragood
Member
I know it's not gold because I let the gold settle and then filtered the solution and put it back in a clean beaker and put another spoonful of SMB into it and nothing precipitated out. The solution stayed clear and nothing settled in the beaker.
What you "know" is there and what is there might be two different beasts.
That is why we test.
Your stannous do not indicate Gold as far as what I see in the picture.
It looks like a false positive.
Often the result if excessive SMB.
A more detailed description might be needed.
Edit to correct spelling
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More often Pd than Pt.
ragood
Member
Excessive SMB can cause a brown stannous test result?
Where would the palladium have come from? I was refining some scrap gold jewelry. Three of the rings were 1920s to 1940s white gold so I thought there might have been some platinum in them.
Where would the palladium have come from? I was refining some scrap gold jewelry. Three of the rings were 1920s to 1940s white gold so I thought there might have been some platinum in them.
I did not say that there are Pd, just that it is more likely to be Pd than Pt in white Gold.
