Stannous Chloride test. Bizarre reaction?

[Rusty2751]

G’day All,
I have some copper waste that came from a copper smelter/refinery after it closed down.
I thought that I would check it for values before sending it off for scrap. I dissolved some chunks in AR and did a stannous chloride test as usual to check for AU. I added the SC to the green/yellow AR .The test turned black immediately. Then after about 5 seconds the black disappeared and the test solution became clear. No colour at all. I thought that my SC might be getting a bit old so I proceeded to process the sample as usual.
Dilution, Urea & SMB. Nothing, not a thing. I am assuming that some other metal or chemical that is in the copper matrix is either giving me a false positive SC test result or is stopping the AU from reacting in the usual manner. Any Ideas or theories would be appreciated.
Thanks in advance
Rusty

 

[Harold_V]

Is it possible that your copper sample contains tellurium?

Harold

 

[Rusty2751]

G'day Harold,

Being from a copper smelter/refiner I would say that it definately contains tellurium.
Regards
Rusty

 

[Harold_V]

I recall having a similar reaction when testing material known to contain tellurium. While I'm not prepared to declare that as the reason for your experience, I wouldn't be too quick to dismiss it, either.

Harold

 

[Lino1406]

You don't have gold there,
but interesting why you assume
it could be there?

 

[Rusty2751]

G'day Lino1406.
What are your thoughts on the results of the SC test?

My rationale` for there being gold in the sludge is as follows
Gold and Copper have a great affinity for each other.
The highest producer of gold in the world besides gold mining is Copper mining. The gold is a by-product of the copper refining process. The sludge, which contains Cu particles, was removed from the smelter and refining cells when the plant closed down. I had similar SC test results from the fine powder in the sludge.
Regards
rusty

 

[Lino1406]

1. As I said, no gold in there
2. Black that turns into colorless liquid -
2a.No copper either, or - you got momentarily
Cu that disproportionated into Cu+1
2b.You got momentarily N+4 (NO2)
2c.At this moment I don't recall other
possibilities, though there sure may be...

 

[goldsilverpro]

I once spent a week at the Anaconda Copper electrolytic tankhouse in Montana. If I remember right, they purified 1,000,000# of copper per day and, as a by-product, they recovered 30,000 oz of silver and 3,000 oz of gold per month. These are only ballpark figures from my memory. They had 2,500, 400 gal cells. If you do the math, you'll see that the Ag and Au are present in the copper only in parts per million. All of the Au and silver end up being concentrated into what is called, "tankhouse slimes". These are the anode insolubles that are collected in the electrolytic cells. They are probably black in color and become quite slimy in a little water.

Therefore, although there are PM's in any metallic copper that you may find, the levels are most probably so low that you would have to dissolve about 100,000 oz of copper to get an oz of gold. This would take about 3,500 gallons of nitric. Not feasible.

The slags are also very lo-grade in PMs.

However, the tankhouse slimes are another story. They are fairly concentrated in Ag and Au. They also contain Se and Te, both of which can be toxic under certain circumstances. Somewhere, I think I have a write-up on refining tankhouse slimes - I'll look. Also, there might be some info on the internet.

My math could be a little off, but I'd bet it's close.

 

[Rusty2751]

Thanks for the reply.

I have about 9Mt of the stuff left over from sieving out the chunks of copper. It has been tested and still contains 16% Cu. I could sell it as is but I would hate myself if I sold it knowing that it contained a recoverable amount of PM's. I remember your entry of refining slimes. I will go back and read it again. I am not convinced that it is totally barren quite yet. I'll battle on for a while more.

Would it be possible that the Acids and Stabilizers in the slime could be effecting the SC test?

Keep the replies coming.

Regards
Rusty

 

[Silver]

I have about 9Mt of the stuff left over

9 Mt????

9 million tonnes??? :shock:

 

[Platdigger]

I think he means "Metric tons". Like...2240lbs each.

 

[Rusty2751]

Thanks Platdigger
for the clarifying that for me.
Regards
Rusty