# Stannous chloride test for silver



## scavenger (Sep 13, 2007)

I processed about 5kgs of crushed cpu ceramic in HCL/Cl and I ended up with a lot of yellow/white gunk in my filter. When I drop Stannous on it it turns dark blue. Any ideas on what this is?


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## lazersteve (Sep 13, 2007)

Scavenger,

If I had to guess I would say it's most likely copper chloride. It should dissolve in HCl. You need to wash the gold foils until the white powder is all gone (HCl no longer darkens or turns blue green).

This is usually caused by low acid levels in the solution. As the solution saturates with copper (I) chloride the copper (I) choride drops out as a whitish powder).


Steve


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## scavenger (Sep 13, 2007)

Hi Steve, I've tried boiling this gunk in HCL to no avail. Nitric wont touch it either. The crushed cpus had been already stripped of outside metals as I was after the gold on the inside. Could it possibly lead from the solder?


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## badastro (Sep 13, 2007)

I've seen this white powder before, and it is quite weird. I thought it was silver chloride at first, but it's something more complicated.

I filtered off the white powder and added base to it. I then evaporated the powder dry and began to calcine it. The volume shrank, and it gave off a flammable gas. Eventually I was left with a glassy bead. I cracked it open and found little balls of silvery metal which I think is silver, but it seems the majority of the material is a non-metal.


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## lazersteve (Sep 13, 2007)

Sorry,

I thought you were using AP to process the whole cpus. I don't know how I made that mistake. 

The yellow is most likely just auric chloride. 

Will the white salt dissolve in plain water? 

Steve


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## scavenger (Sep 13, 2007)

Water has no effect. The powder is kind of fluffy when in solution and sinks fast. I'm sure the yellow is auric chloride but it is impossible to wash it out of this gunk.


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## snail (Sep 13, 2007)

In one of my early attempts to use HCl/Cl I created a similar sounding white precipitate. I was dissolving about 17 grams of well washed foils, when the solution reached saturation, I believed the disolution stopped due to a lack of bleach. I made several additions of bleach causing a lot of gassing and the creation of Quite a bit of white precipitate. I assumed so much bleach was added a salt of some kind was created. It took several additions of HCl and bleach to dissolve all the foils.

I washed the precipitate with HCl and siphoned the acid off several times until it remained clear. When i incinerated the precipitate it formed a rock hard lump.

Dale


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## scavenger (Sep 14, 2007)

Hi Dale, Thanks for your reply. Did the lump resemble metal at all?


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## snail (Sep 14, 2007)

No , but it was only heated enough to whiten the carbon in the ash, a stainless container at a dull red heat. Also the gold was very clean when I started the process.

Dale


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## Flashman (Sep 14, 2007)

Be careful, might be getting some of the dopants from the silicon, which could include arsenic (has a yellowy powderish form) and gallium, or alloys of several combined.


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## NoIdea (Aug 11, 2011)

scavenger said:


> I processed about 5kgs of crushed cpu ceramic in HCL/Cl and I ended up with a lot of yellow/white gunk in my filter. When I drop Stannous on it it turns dark blue. Any ideas on what this is?



Hello - Just wondering if this problem was ever solved?

Started to get into the thread and then ....... :shock: 

Deano


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## Geo (Aug 13, 2011)

could be tin dioxide. it forms a white crystal in the presence of hcl that will not dissolve in straight hcl or boiling water but i think it will dissolve in ethanol, you may want to try that and see if it dissolves. you only get this when theres alot of solder in you stock.


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