Remove trace tin,lead,copper from platinum

[SpudJDog]

I am new to the forum and need help on a very practical problem. I have obtained a very large number of medical catheters, sterile in packaging, that have platinum electrodes on them. I have been removing them by hand and now have a large quantity of them. The electrodes themselves are pure platinum, but each electrode had a small gauge copper wire soldered to it with tin/lead (60/40) solder. I can heat the electrodes pretty high because they are platinum, but that doesn't remove the residual solder or copper. The electrodes are thin wall and tubular, ~ 1-2mm diameter and 2-5mm in length. The wires were spot-soldered to the inside of the electrode. I'm working with electrodes that have been removed from the catheter with minute quantities of solder and copper wire remaining.

 

I have been reading about using aqua regia, etc. to recover gold from things. Is there a similar process to selectively remove the copper, lead, and tin, leaving pure platinum? If I could selectively dissolve the platinum and then recover it that would be OK too, but then I would face the problem of heating the platinum enough to remelt it into metallic form.

 

I have read that copper can be dissolved in acetic or nitric acid, not touching the platinum. There must be similar techniques for dissolving the lead and tin using the qualities of platinum to keep from dissolving it. I have access to common acids and bases and the equipment to do some basic refining such as fume hoods, programmable tabletop furnace, beakers, magnetic stirrers, etc. Also, as an electrical engineer of 40 years I have enough common sense not to do anything stupid. My father was an organic chemist but unfortunately he has passed and I never learned as much from him as I should have.

 

Yes, I want to profit by this, but really only to recover my losses. I was stiffed by a medical device company for consulting fees and went to court and seized their assets. This is the only way to begin to recover my losses. I know I could sell these to scrap platinum refiners, but they want to give me spit for them. I want to do this myself partly as therapy for my sore backside, partly for fun, and mostly because I will retain the platinum as a hedge against inflation in my near-term retirement.

 

Any help would be quite genuinely appreciated.

[John Cuthber]

Nitric acid will dissolve tin, lead, copper, and quite a lot of other metals but it will leave the platinum alone.

If you are doing more than a few at a time I would suggest working outside unless you have a fume cupboard. The by-product of the reaction is a mixture of the oxides of nitrogen and they are not good for you.

 

BTW, please don't post the same thing twice.

Edited September 4, 2010 by John Cuthber

[SpudJDog]

John, thanks so much for the reply.

It sounds deceptively simple just using nitric, but I'm sure you're right and will try that right away. I do have a fume hood and will use it. I've had some experience with nitric, but am very far from being a chemist.

 

Sorry for posting twice. I thought each forum was pretty well insulated from others. Now I know.

 

best regards. I'll post the results for posterity.

 

thanks, again.

[SpudJDog]

I think you mean, stole their assets illegally. If you had acquired them legally, I'm sure you realize that working medical equipment is more valuable than scraps. Which court did you say made this judgment?

 

 

Mr. Skeptic, you have no grounds whatsoever for your comment. I have reported your comment.

 

In fact I was awarded ownership of the company but still had to buy all the equipment at auction because the landlord had a lien on the property. I did so and trucked it halfway across the country at my expense.

 

I have lots of medical equipment to sell if you would like to buy some.

 

Your own ignorance has prevented you from seeing the obvious fact that catheters are single-use devices. These are long past their resterilization date and are scrap except for the platinum. Google electrophysiology (EP) study and enlighten yourself.

[SpudJDog]

I bought 500 mL of 70% Nitric acid (~$15 at Rocky Mountain Reagents, Golden, CO).

 

I mixed it 3:1 acid to water. Any copper wire started foaming green immediately. Lead turned into a grayish sludge, and the reaction seemed to be exothermic. I left it overnight outside and all reaction had stopped by morning. I neutralized the solution and discarded it, rinsing the platinum well. It is shiny and all traces of solder and wire are gone.

 

Thanks again for the help.

[Mr Skeptic]

My apologies. It just seemed really strange to me that taking apart equipment and selling just one part of it for scrap would be worth more than the whole thing, especially if it was still in the original packaging. But that's no reason to jump to conclusions. I deleted my post. If you'd like, I can also vanish this post and any posts related to the subject.

[ammonium nitrate]

just use a candle to remove the lead, it has an incredeubly low melting temperature in comparison to other metals

[John Cuthber]

just use a candle to remove the lead, it has an incredeubly low melting temperature in comparison to other metals

 

Or don't, because molten lead attacks platinum.

[ammonium nitrate]

woops, my bad