fingers in AP working great...stannous not so great

[wildbill_hickup]

Well I started my first small batch of fingers in AP on Saterday and they are almost done. I was surprised at the numbers of foils I got concidering I only processed maybe a dozen fingers... OK so I threw in a couple of pieces of plated jewlery and a tiny 10K chain. I am pleased the way things are going and plan to wash tomorrow night after work. I'm not sure if I'll move on to AC process now or wait till I have more foils. That's the good news :lol: .

OK all that being said I wish I could say the same with my stannous sollution :? . I'm on my second try with no results, here is what I have done....twice. This is based on a post that I read from Lasersteve. It was in answer to anothers question.

2 TBSP Muriatic acid .5g 95% tin solder, cut in tiny pieces (I know Steve you use pure tin). I hope that is not the problem but as I understand it others here use solder 95% tin 5% antimony and it works fine. OK I heated the mixture until solder pieces bubbled and kept heating till they were almost desolved, and set aside to cool a little. I took one of the foils that happened to be floating on top of the AP sollution, rinced it a little and put it in a testtube then added a drop of HCL and a drop of Clorox it fised, the foil disappeared and all seemed well to this point. I soaked up some of the small amout of liquid on a Qtip and then put a drop of stannous on the Qtip. Waited...................... nothing.

So what am I doing wrong??????

 

[Pawnbroker Bob]

I would try your SC directly on a piece of known gold. you should get a dark spot. This will tell you that your SC is good.

I don't know about the heating of the HCL. I just fill up a small eye drop bottle and drop in a big chunk of the same solder you use. It bubbles etc.... I keep putting the solder in until it no longer disolves so I know the acid is saturated. I also leave a bit of solder in the bottle. Seems to keep longer and fresher.

You may not have enough solder in your acid or by heating you may have gotten rid of some of the CL.

PB

 

[wildbill_hickup]

Tried SC on a 10K gold ring. nothing :!:
Should this be an instant reaction or do I have to wait :?:

Well I guess I'll try it your way this time :wink:. I did try and add more solder to existing batch, it doesn't bubble or disintergrate so either the acid is dead or it's saturated. Either way it still dosen't work :!: :!:

Done the way you discribe, how long does it take to disolve solder :?:

 

[lazersteve]

Wildbill,

Stannous chloride will only test gold that is in solution. It will not work on elemental (ie: metallic, karat, foil, etc) gold.

The reaction is pretty much instant.

Are you sure your solder contains tin?


When I make stannous from powdered tin, I apply just enough heat to get the fizzing started then I remove it from the heat. I usually let the solution cool before using.

It's possible if you used and excess of HCl-Cl to dissolve the gold foil(s), your solution is redissolving the colloidal gold (purple stain) that the tin is precipitating. Try gently heating the pregnant gold test solution to drive out any free chlorine and then add a few drops of HCl to it before testing. You may see some salt when you do this, that's normal. The salt should dissolve when the extra HCl is added.

I routinely dissolve a few foils in a small test tube as a control for my stannous chloride and have never had any problems.

Let us know what you find out.

Steve

 

[wildbill_hickup]

Steve, It says 95% tin, 5% antimony.

Ok still working with SC mentioned above (ie. second batch) only I have added conciderably more solder (now I wish I had weighed it) I'm guessing .5g this morning and another ,5g this afternoon. Both desolved leaving only some residue in the bottom. So roughly I have 2 tbsp HCL and 1.5g solder.

I retested AC sollution I had this morning (from some of the gold foils) on a clean filter paper and did get a reaction how-be-it not what I was expecting. It turned yellow/brown :shock: I tried again on a clean spot, same responce. :roll:

I cleaned a testtube and started over this time with a 10K wedding ring. I cut a very small piece and added a couple drops of HCL and a drop of CL, it fized and then settle down I put a sample on the filter and added a drop of SC, same result only fainter I tried again twice same result.

Then I decided to try a Qtip as you suggest Steve and low and behold faint purple. Let it set for about a minute and it darkend I tried the other end of the Qtip and got the same result.

My conclusions are these
1 Not enough solder/tin in SC sollution. I am going to dump this and start fresh. This time I will carefully measure everything before adding. I will heat just until bubbles appear as you said steve I will also keep adding solder to saturation point as PB suggested.
2 I believe there must be something on the filters that is causing the false reading (yellow).At this time I will only use Qtips until testing is more consistant. I like the idea of the filter as you can test more than once on the same filter, but intil I get all this figured out I stick with the Qtips.

OK now that all that is taken care of here is another. Can I test my AP with SC to see if there is any gold in solution? If so, do i add small amouts of copper to drop gold or can I drop with SMB (I think I got the abbreveation right)? As it is now (light emerald green) can this be used again :?: If so I should NOT try and drop gold with SMB, RIGHT :!: :!:

 

[lazersteve]

Wildbill,

Stannous works on AP also. The green color sometimes interferes a little bit, but nothing too problematic (just a green color to the swab in addition to purple).

If the AP has dissolved gold in it and is still nice and emerald green, just reuse it on the next batch without adding any peroxide. A bubbler is fine, but don't add any more peroxide. The peroxide and free HCl work to redissolve the foils and fine gold powder, air does not do this.

When the AP is a nice chocolate milk color the gold should all be precipitated. Retest with stannous to confirm. The chocolate color is from copper saturation. If done properly the amount of gold is so small it's really not worth the effort to go after it until the solution is loaded with foils. Then the gold should come out in the filters as a black powder with the foils.

You can return the solution to the reactive emerald green color with an air bubbler or a small peroxide addition once all the foils and gold powder have been removed.

Steve

 

[Harold_V]

At this time I will only use Qtips until testing is more consistant. I like the idea of the filter as you can test more than once on the same filter, but intil I get all this figured out I stick with the Qtips.

A spot plate won't "break the bank", and will serve you for years. I ran my operation with one from the start and wouldn't have it any other way.

There are times when a test on paper can have advantages-----but I wouldn't recommend not having a spot plate. After all, they're made for performing just such tests.

do i add small amouts of copper to drop gold

I recommend you avoid using copper for gold precipitation unless you are having extensive problems and intend to start over. Even then, scrap steel is an excellent choice, which I'd recommend over copper.

You will struggle to achieve fine gold if you precipitate with copper. It's not selective the way other reagents are. Sulfur dioxide is amongst the best of choices, or even ferrous sulfate. Read Hoke for more information.

Harold

 

[wildbill_hickup]

I will try and find one, trying to get chemistry stuff up hear in the sticks is tough. It took 3 weeks just to find the chemicals that are most mentioned, particularly andything that has the 'nyt' sound, boy I'm glad I don't look arabic. Anyway I picked up an old chemistry set at a yardsale this weekend, it has a spot 'plate' well sort of, it's just cheap thin plastic but maybe it will do till I find a better one. I even got a bonus, a full jar of copper sulfate, no test tubes though, damn. Well I guess I can't expect much for a buck.

Steel it is when I'm ready, according to what Steve said if I understand him right I will just keep using the same sollution again as it is still pretty light in color.

I'm up to the chapter on silver in Hokes book. But I got impatient and finally had all the stuff. I just had to process those fingers. Now that I have that out of my system I can get back to the book. I'm not much of a book worm, I have to see it work to really understand. Thanks to all for the help I'm sure I'll need more! Maybe I'll even be able to give some back one day!!!