supposed problem with chelating resin

[ander]

Hello,
I got some purolite S-920 chelating resin. It's thiouronium resin dedicated to remove mercury, platinides, gold and silver.
Here's the problem:
I read that recommended column lengt is not less than 1meter, and there should be two columns connected, so the total resin bed is 2m high.
Also, there is recommended flowrate 10 bed volumes per hour. I made my "column' as 3X 100cm long hose, 6mm inner diameter, filled with resin in 90% of length.
I calculated that total bed volume is around 70ccm, so flowrate should be no more than 700ccm per hour. I made test and i got around 500ccm per hour so i match
the limit. But:
I used dissolved scrap containing: copper, nickel, some iron and of cource gold. Its color was greenish. As soon as the solution reached the bed surface in column its color turned slowly to yellow, red and finally brown. As it flows thru the column its color is fading back to yellowish-green. I put some SMB to, I supposed, gold-free soluion from the column but it clearly showed that there is lot of something that reacts as gold.
The Questions are:
What did I do wrong?
I did not rinse column with anything but DI water prior to gold extraction attempt.
Do I have to do some kind of conditioning before use of fresh resin?
Is Purolite resin not so gold specific as the company claims and reacts with other metals such as nickel or copper?
Is there any possible problem with urea added to remove excess of AR?
Should I sompletely remove nitric ion from the solution? And how to do that?
Is there possibility that resin frees some thiourea to solution ant that makes the color?
Is ther possibility that resin reduces gold to nanoparticles which then dissolve back in acid solution?

Regards,
ander

 

[butcher]

ander,

I really have no clue, a quick look at this ion exchange resin, seems to indicate it is for dilute solutions to remove metal ions from water, not aqua regia, oxidizers apparently destroy the resin, I know nothing of this ion exchange resin.
They also mentioned about running the water through activated charcoal first, this to me sounds like a way to treat water to clean up a few metals before putting water back into the environment, not a process to recover gold.

I just quickly goggled this Ion exchange resin and glanced over the paper, so I really do not know much about it, and could be wrong about what it can do, or what it is intended to do.

Why are you trying this resin? Are you working with ore? Is this just something you are experimenting with, or is there a reason to use this instead of conventional processes?

The chemical soup your running through this resin is this what the manufacture suggested or is it something you thought might work?

Sorry I cannot help you, all I have is questions, maybe someone else here has some experience with this ion exchange resin they can share with you.

 

[ander]

butcher,
I read that someone was using it to recover metals from e-scrap and also got some info from people involved in resin industry.
I have lot of diluted solution with high concentration of contaminants like aluminum and zinc. I tried to use SMB but the gold was in form of so tiny particles it did not settled after a month.
I probably found the problem as i forgot to check pH value. I adjusted it to 2 and now the solution is brown and some fluffy sediment is forming slowly. I'll try to filter it off and then run it thru the resin.

 

[Lou]

I will send you some contact info.