Iodine Flux for the precipitate

[donnybrook]

I am still having some problems with smelting the precipitates after leaching with iodine. I have been following one of the tecniques which suggests converting your gold and silver iodides to gold and silver chlorides by adding Clorox (or Chlorox), adjust the pH and then drop out with SMB.

Other information suggests that the precipitate be boiled in Lye to convert to an oxide,then roast for 2 hours to convert to a metal.

I do not believe that the gold is dropped using SMB as the Sodium Hydroxide itself brings all metals down at pH7. That these are chlorides and as platdigger said "they (the gold Chlorides) are probably going up in smoke"?

Coconut fibre has also been suggested. It is something not commonly available where I live. Activated Charcoal is used in fish aquariums and perhaps this is the same thing. A carbon based material?

There was also another post somewhere in the Forum on recovering the iodine by adjusting the pH usining white vinegar. Has anyone seen this method?

Any suggestions.
donnybrook

 

[Platdigger]

Donny, if you go back and look, I never said anything about gold chlorides.

If you truely were able to convert the gold to a chloride......all you would have to do at that point is, drop with your favorite precipitant, or cement it out.....end of problem.
Randy

 

[4metals]

Raising the pH of iodine solutions containing gold iodide with potassium hydroxide will drop the gold and produce potassium iodide. Quick drop and color shift when the gold drops out of concentrated solution.

 

[Anonymous]

Metals
will the gold be of a size large enough to filter? or will it have to settle and be decanted?

Thanks
Jim

 

[4metals]

I have used this method to drop gold from iodine etch solutions used in electronics manufacturing. Never had any issues filtering the solution.

 

[donnybrook]

Thanks Randy,
I purchased a method from someone not in Australia. They say add clorox or chlorox home made (instant colour change as the red dissapears and the brown remains). Then adjust pH using hydrochloric acid and sodium hydroxide or Lye. Add precipitant at a pH of 7(I used SMB). The gold should drop as a sulphide. The method I purchased from a company not in Australia then said "you will not recover your iodine using this method"?? Why not? Can this be answered?

There are two products or chemicals sodiumetabilsulphite or sodiummetabisulfate. One of these will not work (??) or in any case if the precipitant is not fresh it does not work or as effectively. Many of the texts including that by Hoak which I last read about 16 years ago said it "the precipitant must be fresh". The same with cupperas which you make by boiling a garden product and filtering for the solution or make your own using scrap iron and sulphuric. Its easier from the packet as long as the product is fresh. Moist air on days of high RH can destroy your SMB or just long periods of storage.

Lye will drop everything. It will drop your metals as a black precipitate which will go brown and can be filtered. Did I drop a gold chloride which the other writer said it was ? Other references to this say you should boil in sodium hydroxide to convert your gold chloride to gold oxide. No logic to this suggestion if what is said in the first instance is accepted as the "Procedure". Keep the pH below 12 as you will take up the platinum group metals (at pH 13) for two hours. It then becomes an oxide of gold and it should then be roasted to convert back to metal or gold metal with no visible yellow colour as such as described within the purchased information. You can hear the excahnge or conversion taking place within your dish. Some of these references are also on the Web.

The error has been mine. They say never blame your tools. I dropped a gold chloride or a chloride in some form or even a hydroxide off gold, I failed to do the correct thing, and guess what, I blew it. I will repeat the experiment. Take more care next time.
Donnybrook

 

[eeTHr]

Being a beginner myself, I can't really recommend anything; but---

Here is a site where the author says he is both a prospector and a chemist.

On this page, scroll down to the "Leaching" section, and about halfway down that section he explains how to recycle your iodine, and below that is the "Recovery of the Gold" section.

http://www.prospectorsparadise.com/html/leaching.html

His methods are very much simpler that what you described in your top post.

I have never tried it, so I can't absolutely say for certain.

 

[donnybrook]

Thank you eeThr and other Forum members for input on this topic. The method and website page referred to was written by the late Ken Williams. A great man and fellow Prospector who would always respond to your emails if you had a problem when he had time. It is the most direct method which I will get back to you on after running the experiment again using a few pounds of tabled concentrates from two locations. Other small clues on the Forum suggest adding a full strength (9% or 7 %) solution and letting the iodine work for a few days in a sealed container, then later dilute with water. I will add a small hole to the top of the container ( a beer brew drum) as I am sure there would be some reaction and container expansion subject to environment and temperature.

I have made up some Clorox or Chlorox using his method and dry swimming pool powder. The end product is probably 50% strength. Stored it in a cool place as I think the commercial product here in Australia is only about 12%. It is just a super strength bleach which under normal circumstances loses its potency on the shelf.

I have used both the Iodine leach and also the SSN (or SWAN Leach) on different samples taken from different locations hundreds of miles apart. I ran the SSN Leach on the same type of sample I had problems with using iodine and it produced a heavy precipitate.

They say "different strokes for different folks". So perhaps the same "dictum" applies to different ores or concentrates.

Donnybrook

 

[donnybrook]

Randy,
No you never said "it will go up in smoke" it was something said by someone else. I apologise for quoting you as having said that.

Regards,
donnybrook