stannous chloride test

[khaledmo]

hello
i have a chemical test for a sample of rocks
can anyone tell me if its test is a definitely result that gold or precious metals are present ?
and the ratio is economic ?
ore is 1 kg
the solution is 500 ml
test with stannous chloride to aqua regia

 

[FrugalRefiner]

It might just be my screen, but it doesn't look purple to me. Then again, since you used AR, there might just be too much oxidizer left in the solution.

Dave

 

[khaledmo]

It might just be my screen, but it doesn't look purple to me. Then again, since you used AR, there might just be too much oxidizer left in the solution.

Dave

thank u sir
Yes, I did the test before neutralizing nitric acid
is that problem ?
i wash the ore with nitric acid about 12 hours before using AR
stannus chloride does give reaction like that with non-precious metals ?

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[FrugalRefiner]

If you have excess oxidizer in your AR (in your case the oxidizer is the nitric acid), as soon as the stannous chloride reacts with the gold in solution to create the distinctive purple color, the excess oxidizer dissolves it again. You may never even see a change of color because the two reactions are happening at the same time.

Stannous chloride does give reactions with non precious metals. Copper can create a brown reaction that many refer to as a false positive.

I have never processed an ore, so I'm far from the best person to help you. I'll hope Deano sees this thread. He is the authority when it comes to working with ores.

Dave

 

[khaledmo]

If you have excess oxidizer in your AR (in your case the oxidizer is the nitric acid), as soon as the stannous chloride reacts with the gold in solution to create the distinctive purple color, the excess oxidizer dissolves it again. You may never even see a change of color because the two reactions are happening at the same time.

Stannous chloride does give reactions with non precious metals. Copper can create a brown reaction that many refer to as a false positive.

I have never processed an ore, so I'm far from the best person to help you. I'll hope Deano sees this thread. He is the authority when it comes to working with ores.

Dave

This is exactly what happens
after the reaction of stannous chloride it redissolved in acid and the color is gone .

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[Lino1406]

With positive test, black or brown should stay, with additional color ring (to the original). If vanishing, even after prolonged time - negative.

 

[khaledmo]

With positive test, black or brown should stay, with additional color ring (to the original). If vanishing, even after prolonged time - negative.

thank u sir
Even if there is a large amount of nitric acid ?
when i dilute solution the blach color is stay

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[Lino1406]

Stannous test, by itself is not a proof. It is to be followed by dropping an amount and testing the precipitate in particular test for the expected metal

 

[g_axelsson]

Put a solid piece of copper into the solution and look for any metal cementing onto it.

If you have excess nitric acid the copper will dissolve, using up the nitric acid.

Göran