Testing A/P solution with stannous

[golddigger2]

Hi I'm just wondering if there is any problems testing A/P for the presence of dissolved gold with stannous chloride? I have been using the A/P process for about 2 years and have always tested spent solutions with stannous. I have never had a positive test for gold and have never seen black precipitated gold powder either. I must assume therefore that I am using the process correctly. I just want to know if there are any pitfalls to testing this particular solution with stannous.

Thanks

 

[dtectr]

good question. I have been wondering about that, as well, as some early material had solder traces.
I look forward to responses on this topic.

 

[lazersteve]

With AP you must make sure the solution is saturated with copper to be sure no gold is present. The color of a saturated AP solution is dark chocolate brown.

As for testing Acid Peroxide with stannous chloride, I find that a positive result will take a few minutes to develop before the purple/black color appears. When the stannous is initially added the solution/swab will lose some of it's color, then the positive result will develop shortly thereafter. Testing your stannous chloride against a standard solution (known positive) mixed with a little brown AP solution will give you some practice recognizing this result.

Remember your stannous can go bad so be sure you always have a standard solution on hand to confirm your stannous is up to par for testing.

Steve

 

[golddigger2]

Thanks steve excellent advice as always. I have another question about cleaning the copper powder once it is dropped from the A/P I know it's on the forum somewhere as I have read your post before. But I have tried the search on goldrecovery .us and the search function on the forum would someone please be so kind as to post the link?

 

[lazersteve]

Is this the one?:

Copper from Spent Solutions

Steve

 

[Marcel]

Btw: I dip the Q-tip into the AP solution first and then put a drop of Stannous chloride on it.
Since the reaction is weaker I suggets to go that way, otherwise you may dilute the Stannous Chloride too much by dipping it into the AP .
If using SC with AR it doesn´t matter because the reaction is so fast and strong.
Or do you think it wont matter with AP as well?

 

[golddigger2]

Thanks Steve but I saw a post a while ago where you explained how to cleanup your waste copper powder to get it ready to sell. I know you could use 95% sulphuric but as the copper is dirty I'm worried it may react with other metals still in the dropped copper like steel

 

[lazersteve]

How about this one:

Acid Peroxide Clean up


Steve

 

[golddigger2]

That's the one. Awesome thanks Steve

 

[golddigger2]

Does having a small amount of copper in hcl/ chlorox have any adverse effects on precipitation with Smb?

 

[maynman1751]

Does having a small amount of copper in hcl/ chlorox have any adverse effects on precipitation with Smb?

No, not really. You may have some drag down of copper with your precipitate but that can be eliminated by proper washings and re-refining.