Iodide+ AR

[ander]

Hi everybody. This is my first post, so please, be patient. I'm a chemist, but I work in a totally different division in chemistry. My father has a lot '70-'90 of e-scrap. To dissolve gold many different compositions can be used. To dissolve "purified" gold we use bleach and HCl or AR. To dissolve gold from a mixture we can use complexes like triiodide at low pH. I made single attempt to dissolve gold flake in KI3, and it certainly did dissolve, but it took 2 days @ 10C degrees( garage test). I made some more 9% I2 solution and it hardy works. Thiosulphate leach also isn't suitable- it dissolves copper too, and it does it very slowly. So my question is: have aybody tried to use a mixture of nitric acid- iodine or iodide+iodine, or other stuff like KI3 +H2O2? The goal is to get gold and leave Ag, Cu, Be, Pb, Sn. Cadmium iodide unfortunately is soluble in water, but there is not much of that beast in alloys. What are Your opinions? Does it make any sense? rgrds

 

[Juan Manuel Arcos Frank]

Ander:

Welcome!!!!!!. Where are you from?

Both processes have been discused in this Forum.You can find the posts using the search box.

About thiosulfate process you need to add some cupric salts as catalyzer to make it fast enough.

Kindest regards

Manuel

 

[ander]

I'm from Poland, middle-eastern Europe. Of course I made both solutions accordingly to numerous advices (patents, books). But I couldn't find any attempt of using iodine with nitric acid or hydrogen peroxide do leach gold. I'm thinking of some kind of "Iodine AR" wherein the complexing anion is I not Cl, which salts of Cu or Be are soluble. Time is cruicial, that's why I's seeking for extermally strong mixture- chemicals are no problem to me.

 

[Juan Manuel Arcos Frank]

Ander:

Well,it sound interesting.How about to try it?...make some AR,add some I2 (or KI) add some gold and let us see what happens.

Pozdrowienia

Manuel

 

[ander]

I set 4 test probes with 3 different compositions. 3 of them contain 20% nitric acid: first one with potassium iodide, second one potassium iodide and iodine, third one same iodine. The last one is 65% nitric acid with iodine. The problem is that nitric acid has much higher oxidative potential that hydroiodic acid could bare so both solutions with iodide got oxidised to free iodine. Same iodine is very slightly soluble in nitric acid so the solutions 3 and 4 are only pale yellow. It seems that 65% nitric acid oxidises gold plated pins but very slowly. I can't find any way to create I- ions in the solution due to the oxidising nature of nitric acid. The fourth composition dissolves also lead I suppose- solution gets milky after a while. I also prepared AR+ potassium iodide and it seems better than others I made. Tomorrow I'll have results.

 

[ander]

I was naive. The method with mixing nitric acid and iodine is waste of time. Only two compositions worked- poorly, long time, dissolving all metals- and making mud like mixture of iodides on the bottom.

 

[Lino1406]

Iodides do not exist in the presence of
HNO3

 

[ander]

Iodides do not exist in the presence of
HNO3

Insoluble ones do.

 

[johnon]

I've used thiosulfate w/some success on ores and mine wastes; the trick is to use catatytic amts. of copper metal and NH4OH To adjust pH to 9-10. Decant lixiviate & slimes, treat w/ CO2 & let settle (flocculate w/potato starch if necessary); decant supernatant, boil & titrate -add thiosulphate to 0.8M and you've regenerated your leach (you'll also precip additional cons.). Treat cons w/acetic or other weak acid to destroy residual thiosulfate & fire; you'll have to work w/your flux a bit get a bead. This method is a work in progress; am interested to see if I(minus) would help. Will try and get back to you.

I love this bar :lol: .