An alternative passive stripping system

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S

Shecker

Well-known member
Joined
Apr 1, 2008
Messages
241
Location
Gunnison, Colorado
I have been experimenting with another passive stripping approach to e-scrap that seems well suited for such things as cpu's, pins, fingers, monolithic capacitors, etc. I've been using a dilute solution of veterinarian grasde Povidine Iodine. I make an iodine solution that has a thin red color (iodine water). This dissolves gold, silver, platinum, palladium, but does not react with lead, tin, aluminum, or copper. As the solution begins to become saturated it starts dropping out some discrete particles of precious metals. It will continue to do until the solution looses it stability and goes clear. I ran some CPU's today and after about two hours the precious metals were laying in the bottom of the container. No precipitation was required. Forum members working with iodine may give this try and report their observations.

Randy in Gunnison
 
Just enough to make the water reddish-brown but you can still see through the solution. If the mixture becomes opaque add more water.

Randy in Gunnison
 
As the iodine is exhausted tiny bits of metal will fall to the bottom of whatever vessel you would use. There will also be a golden yellow solution left over which still contains gold. I recover most of that on carbon but I am still working on the residue gold left in solution.

Randy in Gunnison
 
can this be used to make solution you are talking about?
IODINE CRYSTALS 50g Top Quality Material 99.9%
Ebay Item number: 120462660705
 
I would guess Povidone Iodine is just a convenient source of elemental iodine like you found on eBay.

http://en.wikipedia.org/wiki/Povidone-iodine

I have read some things on iodine leaching but never really studied the process. You should be able to recover and reuse the iodine repeatedly.
 
This is a very interesting alternative. I was a bit weary of using Aqua Regia even though I have access to HNO3 and HCl... I'd much rather use this process, which looks much less dangerous. Does this process generate noxious or oxidizing gases? Can it be done indoors or is it preferable to do this outdoors?

I imagine this process must be quite slow (but I don't mind). So the metal precipitates directly at the bottom of the container? i'll try it on a handful of old gold-plated semiconductors to see if it works!

Robert
 
I wonder if Betadine (I have a pint bottle)which is a stronger solution of drugstore iodine would also work, I guess it should.
After you filter the precipt out then would you filter thru activated charcoal or use some zinc or iron salt(forgot the name)? Which would work better?
Wyndham
 
allrighty, heres a question......

If this solution "self precipitates", i would guess the crushed cpu's or pins would have to suspended in some sorta basket, as having the precipitation mixed with the materials would not be practical?

ryan
 
I was thinking of a plastic strainer for testing. I found out that Betadine is provodine at 9-10%.
What do we use after cleaning up and dropping the gold out of solution to recharge the iodine?
BTW it was iron sulphate, I think that I was referring to, to drop the gold out of the remaining solution.
Wyndham
 
Hello all,

Seems my first attempt at gold recovery was less than a stellar success... :(

Since I have no access to a fume hood and I live in a densely populated area, the Aqua Regia process would be very hard for me to attempt, so I decided to try out the iodine solution process.

So I attempted the experiment on a small scale to see if it works, and since iodine dissolves better in ethanol than H2O, I used that instead, but I decided to have a more concentrated mixture than recommended by the OP to see how fast it works.

In a small 50 ml flask, I added:
15 ml of Proviodine 7.5%
20 ml of ethanol 50%

aui_proc.jpg


Then I dropped a small piece of Pentium in the flask and I put a cork stopper on top. I let the mixture sit for over 48 hours, thinking that I would have my little pentium chunk stripped clean of gold, but to my surprise, the pins and the gold traces on the creamic substrate were totally unaffected.

So either I did something wrong, or the process itself takes a very very long time... The OP mentioned that he only used water and his mixture was just a "thin red color". My mixture was much more concentrated than that. So before attempting anything on a larger scale, I just wanted to ask the fine members of this forum who had success using this process if they have any recommendations, mixing ratios or suggestions they could share with me... :)

Robert in Montreal
 
roddenberry;

Being a beginner myself, I have not yet earned the right to rant or have pet peeves (with a small exception in the Bar and Grill section).

However, I would like to say that I am always confounded when someone states that they tried a certain formula or prosess, when in fact they have actually altered that specific formula or process! The way to test something like that is to duplicate what was stated, exactly. Then if a person wants to try to improve it, fire away, and maybe you can make something better. But don't skip the step of duplicating the stated method first!

roddenberry said:
So either I did something wrong....
Click to expand...
Hmmmmmmmm.


roddenberry said:
members of this forum who had success using this process....
Click to expand...

The original poster of the process says he had success, and he has listed all about how to do it. What's to question?

Actually, I've mis-applied processes myself :oops: , thinking I would outsmart the experts, but surprisingly :roll: none of those attempts succeeded. But I'll always try to improve something once I have gotten it correct, if I have a good enough reason to think it would be likely to work better. And maby it will work, and maybe not, but at least I will have a working reference to judge it by, which would be the duplication of the process as stated to begin with.

Well, now that I haven't ranted, maybe one of the experts can tell you what happened to your process. :lol:

Sincerely,
Don
 
Hello Don,

Sorry that I am the target of your rant for one of my first posts on this forum... The actual fact is that I have read several documents and texts, including a US patent (3625674) dating back from 1971 that states:
Au + H2O•C2H5OH:I = AuI + H2O•C2H5OH so the only "improvement" on the original poster's recipe was that I followed a more detailed and better described recipe that includes alcohol to keep a maximum of free iodine in the mixture.

I am not a chemist, but I do have elementary knowledge of chemistry and how chemicals react with one another. (always been fascinated by chemistry when I was a kid). Still, I prefer to follow a recipe that has a more precise description of the ingredients. The OP's description was rather vague. One element that isn't mentioned anywhere is the time of the reaction (a minute? a day? a week?).

Anyway, I didn't want to ruffle any feathers with my first post, just get a bit of wisdom from folks who have tried this process and have suceeded. Is heat used in the process? Does the process need a larger quantity of ingredients to "kick in"? Is there a catalyst used? I am simply trying out the process with what I have and gathering more information on the process until it works.

Experience is acquired by a series of trials and errors. My first test didn't work, but it doesn't mean that with a little TLC and a bit of luck, I won't get it right next time. :D: :lol:

Robert
 
Robert;

Well, I don't want to ruffle any feathers either, and I apologize to you for being disrespectful.

I, personally, welcome any new methods which would make processing e-scrap more viable; and I feel that the way that would come about is by people like you who get ideas, and then have the wherewithal to actually try them out.

But it does irk me to read, "I tried the process posted above," and then it turns out to have one or more things added or subtracted. I just go "Huh? That wasn't the process!" You know what I mean? Also, it makes me wonder how they would know if it was an improvement over the original method, if they didn't do the original method as a reference?

Anyway, I see what you are saying, and I can't disagree with your logic.

Now maybe someone who knows what's up with your process will shed some light on it.

c u L8r,

Don
 

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