Aesthetic Iodine/Iodide Precipitation

[solar_plasma]

0,7 g gold; from the purple precipitate, it got very dark when dried.

So, together with the cementated almost black powder 0,9 g. An unknown amount of later cementated precipitate is still filtering. The first half of it was brown (gold?), the last half of it is grey (palladium?)

 

[solar_plasma]

clearly to see: a grey layer above brown stuff

the dried purple pricipitate has a high density (left), it's 0,7 g. The dark powder (from first cementation) on the right weights only 0,2 g!


81,8 g leached scrap left back. As you can see, it was mostly RAM's and comparable material.

 

[solar_plasma]

3,7 g (above)
0,7 g (left)
0,2 g (right)
___________
4,6 g unrefined gold (I assume some palladium, because a part of the cementation made grey powder. I guess about 0,1g can still be scrubbed off the material and some 0,1 gramms will maybe be collected, when I've cleaned all vessels)

 

[lazersteve]

Got any photos of the melted gold buttons and their final weights?

 

[solar_plasma]

No,I want to refine the material first and that means reading, reading, reading ...and understanding

BUT I have made a test with DMG on the grey powder, so this should be palladium, right?:

 

[ericrm]

finger and such look indeed to be copper,did you look with an pen eraser, or scratching with a knife to make sure you are 100% positive that you have leached your gold and not only deposited a fine deposit of metal or iodine as on my computer it look pink/purple and spotted rather than a very pale pink from virgin copper. i should receive my iodine in about a week and experiment just like you...

 

[solar_plasma]

The copper fingers look like freshly etched copper with some spots of cemented palladium. It's pure copper for sure.

 

[lazersteve]

Solar,

Your photos are too distant from the test tube to be able to get a close up view of what is in the test tube. Get your camera closer to the test tube and set it to macro mode to take a closeup, detailed photo of what's in the bottom of the test tube like this one:

Steve

 

[solar_plasma]

Thank you Steve for your sceptical questions. I retried and this time no yellow. Paradox. I incenerated a very smal piece in a tube till red glowing heat and purple fume occured, there is a copper-reddish spot in the middle now - the grey powder must have been some copperiodide?

Then I testet one black piece from my purple precipitate with a little torch, it didn't get hot enough to melt, but here occured nothing unexpected. I retry later by autogenous welder, when I have time again.

I know, I have to be sure before I go on. I will find out.

Thanks.

 

[solar_plasma]

I've heated some very small pieces with oxygene and it melted. It's a silver white metal!!! ....any ideas so far? ....and it is magnetic! wow,I have made nickel metal? :roll: maybe 2% nickel alloy and I have found the 2% ultra pure...nickel? :roll:

 

[solar_plasma]

Mistake 1: I've heated some grey powder, assumed Pd), I didn't know for sure, what it is (small amount, but neverthess, also small amount can cause diseases or explode)

Mistake 2: Since my SnCl2 seems not to work,I have not tested the black/purple material, assumed gold, for gold ...that was stupid.

I think two mistakes are enough to learn of on one day.

I will first go on, when I could test positive for gold. Then I want to wash the material first with clean KI to get all iodides washed out, then with hot water, then like Harold V. advices with inceneration and washing with acids before melting. I have to read this point again and I will ask, if there is something I don't understand.

Lesson learned today: Never think you are smart!

 

[lazersteve]

Be careful incinerating compounds containing iodine, the thick purple iodine vapors are poisonous. Iodine will also stain (red to yellow brown stains) just about everything it comes into contact with that is organic. It's best to heat iodine compounds in a closed system with a cold finger condenser to trap the iodine via sublimation as the iodine vaporizes upon decomposition.

Steve

 

[solar_plasma]

Yes,that's a good advice, since I can not be sure to be able to leach all iodides out with the KI-solution and thereafter with water. I thought of bubbling the fumes through sodium thiosulfate at the end of the assembly and to lead an inert gas through the vessel with the stuff that is to be incenerated, so the fumes will be borne through the assembly. What would be inert? with glowing base metals they could react, though...or bad idea at all? I have no Helium, that would be nice.

Edit: since I have no helium, I will not send any gas through it. I'll build a condenser and for safety thiosulfate at the end. Then I can reuse the gained sublimate for a new Lugol's solution.

 

[solar_plasma]

For all those who followed this thread and who are as new to iodine as me: I think iodine is getting interesting at a point, at which I hardly would do experiments and learn just by reading (look: http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=34&t=4301&start=40)

I consider the NH4I-method to be highly dangerous, if you not EXACTLY know what, how and when to do! Well, nothing I will "try out" by a recipe. I wished, some of the iodine-experts would live nearby. NH4I seems to do, what I had hoped KI/I could provide.


...and hey,the chlorox-method is lovely! Very nice to controll. Since today I guess I have a new favorite! :lol:

 

[solar_plasma]

I've ordered an ORP-electrode for my pH/temp/I/U-multimeter, now. I have not given up, so far! 8)

 

[ericrm]

so i just started to play with iodine this week and here are the result

i used high purity i and ki and demineralised water 1/ 4/ 10 by weight

the etching rate is indeed fast
but it cemented back on the item...
i dont have the picture but i have leached finger with iodine and disolved the "aparently non gold bering finger) in ar the result "seem to be" a positive for gold....
and i did got a lot of with yelow and purple unknow precipitate...

i have a question for those who knows better than me, am i trying to make gold iodide or gold potassium iodide?

i will try more in the next week but for now like stuk like everyone else...

 

[ericrm]

i just made a second try with 6g I/ 26g KI/ 176g h2o and the result are worst... on a little " plated bracelet" the solution seemed to attack base metal faster than gold and let gold in flake when i was shaking it.it also make a lot of whitish precipitate...

i tryed with a finger from memory and all it did was to cover the finger with a dark residu, i have removed it with a paper towel ,and it is blue.. i suspect that iodine plated on the gold...
i dont know what im missing ...

the white stuff seem to apear on contact with copper/ base metal under the nickel layer...

edit ... it is copper(i) iodide thank you wiki

 

[solar_plasma]

gold iodide or gold potassium iodide?

I read only about gold iodide AuI3 (edit: no, I meaned AuI). KI is only present in order to make the iodine solvable, as far as I understand. Could any chemist or hydrometallurgist say something to this?


In the summer vacation iodine will be one of my projects again, this time with ORP-meter. I guess without, you have no chance and, like me, end up with a copper, cobalt or nickel button. I do not expect the great success. Until now, I am come to the believe that the selectivity is widely overestimated or at least only benefits in special settings like ores and/or big leaching units.

Is there anybody who used this really succesful on small-batched e-scrap? And if, - how did you do it?

I wonder, if the cementation could be avoided by a steady flow of fresh leaching solution. Then the solution, that "filtrated" through the pins e.g. could be separated from the gold by for example electrolysis (if it was only iodine solution without KI) or resin. The solution would have to be regenerated and would newly flow through the gold plated material. But again, this would probably only work in a big well-controlled unit.


But what is wondering me mostly, is the fact, that no paper tells anything about the cementation problem!

 

[solar_plasma]

Back to the reason of my sleepless nights:

I believe precipitation of gold III hydroxide will be a way to go. Gold III hydroxide, formed from gold I iodide by adding NaOH or KOH, which leaves NaI or KI in solution, forms oxide when dried, which decomposes at only 160°C to its elements. Most possible basemetals will form hydroxides too, which mostly will be soluble in acids, others allmost insoluble in acids. So, they should be easily removable before further treatment of the gold. So, decanting solution from hydroxides, rest gets vakuum filtered, NaI respectivly KI re-uses by oxidation of iodide to iodine. Hydroxides are heated to 200°C and get acid washed thereafter. Gold remains in the solids together with acid resistant compounds

Comments are welcome. Otherwise I crack that nut alone, if I have to! *dreaming* then aaaaall the honour is mine undevided ...no, any helping on the right track is very welcome! Ti-i-i-ime is on my side. 8) :lol:

Btw: To all other newbs: this is an alternative recovery method, which I am trying to understand and learn. I think it contains unnecessarily many steps compared to the usual methods. It is nasty. It is poorly described on the net. There are good reasons, why AP, AC, AR and sulfuric are the common methods

 

[ericrm]

solar_plasma, how will you deal with your copper iodide waste?