Iodine leach

[Yggdrasil]

for high ph level

????
Please explain. Why do you do a thing...
you do a thing for a purpose, what is that purpose and why.

 

[orvi]

You need acidic solution, take pH paper and add HCL till you get pH around 2 and less. That should be good enough. SMB is added to the point when reaction mixture clears up significantly (destroying iodine) and then a bit more (like a spoonful for dropping gold. I do not exactly know how much of the iodine was in.

 

[rakno91]

????
Please explain. Why do you do a thing...
you do a thing for a purpose, what is that purpose and why.

i just read it said so. although i had a very little knowledge of chemistry so as a first timer , considered it a step that i had to raise ph then i had to bring ph down with ascorbic acid for result

 

[rakno91]

You need acidic solution, take pH paper and add HCL till you get pH around 2 and less. That should be good enough. SMB is added to the point when reaction mixture clears up significantly (destroying iodine) and then a bit more (like a spoonful for dropping gold. I do not exactly know how much of the iodine was in.

the solution was iodine1: potassium iodide 2:water10

 

[4metals]

Probably 30 years ago we used to get in drums of iodine etch solution which was used to selectively etch hybrid microcircuits. They were loaded with gold and simply adding KOH released the gold and regenerated the iodine to make KI which was used to make more etchant.

 

[orvi]

Probably 30 years ago we used to get in drums of iodine etch solution which was used to selectively etch hybrid microcircuits. They were loaded with gold and simply adding KOH released the gold and regenerated the iodine to make KI which was used to make more etchant.

Yeah, phase diagram is right about this, and of course, simply KOH will do the job. But I assumed he has base metals in there, which will precipitate as hydroxides and complicate the workup procedure. Not quite a problem, but filtering that could be painful.

 

[manorman]

Why are you adding NaOH?

 

[manorman]

It sounds like he he adding NaOH inbthe wrong step, I believe it should be used after the gold is recovered using vitc or SMB. NaOH will recover the KI

 

[4metals]

Even if base metals were present, which they were not in the application I mentioned, they can be separated out after drying the precipitate and acidifying in Hydrochloric Acid which would likely re-dissolve the hydroxides leaving the gold as an insoluble.
Of course every application is different and may present different hydroxide impurities, but the bottom line is the gold will be down and a little experimentation will show you the right path to purification.

 

[rakno91]

It sounds like he he adding NaOH inbthe wrong step, I believe it should be used after the gold is recovered using vitc or SMB. NaOH will recover the KI

hi manorman
can you guide me from step 1 to finale.the gold stripping material could be e waste,or the base metal may be copper or ss.thanks

 

[Simplestar]

I know this is an old thread but I am curious if anyone figured out what the black sludge was from? I seen two posts about it somewhere in this thread. Could it be povidone that causes that?