# A mixture of Indium/Copper/Iron/Nickel in AR



## zephler (Apr 16, 2014)

how would one go about separating the metals out? Yes, it is possible to do it with D2EHPA, but what about selective precipitation by adjusting the pH or with precipitation using NaSH? I would think that cementation or electrolysis at this point would not work very well.....


----------



## joubjonn (Apr 16, 2014)

Remember, indium is $0.60/gram. Have to ask yourself "is it worth the trouble"?


----------



## zephler (Apr 16, 2014)

I really am starting to think that the only option here is to go the D2EHPA route, as filtering hydroxide sludges is damn near impossible, and any Fe present will kill an EW attempt....hrmmm...might just have to leave this one alone


----------



## joubjonn (Apr 16, 2014)

Cement it with copper. That would leave you with just the Indium. Probably not 99% but close to it.


----------



## zephler (Apr 16, 2014)

thank you! At pH would you recommend to cement at, and is it the Indium that would fall out, or is it the other metals that would fall out?


----------



## joubjonn (Apr 16, 2014)

no need to adjust it, just place a nice thick piece of copper in the solution for a week or so. decant and save the powders, everything below copper in the periodic table will come out, leaving Ni and Iron in solution.


----------



## zephler (Apr 16, 2014)

Thank you for your input!

Do you mean Electrochemical Series, not Periodic Table? I am having trouble finding an electrochemical series table with Indium listed on it, do you by chance have one handy? As for pH, so a pH of 1.5 is fine?


----------



## joubjonn (Apr 16, 2014)

Search the forum. It's been posted many times. As well as cementing threads and how that works. You will find everything you need with the search function.


----------



## Platdigger (Apr 16, 2014)

Actually Indium is more reactive than copper so should not cement to copper.


----------



## necromancer (Apr 16, 2014)

joubjonn said:


> Remember, indium is $0.60/gram. Have to ask yourself "is it worth the trouble"?




only if you have a element collection, mine has started, 1oz Au, Ag, In, just can't figure out how to display an ounce of O2


----------



## kurtak (Apr 17, 2014)

Platdigger said:


> Actually Indium is more reactive than copper so should not cement to copper.



correct

Kurt


----------



## g_axelsson (Apr 17, 2014)

I'm also interested in it. I have some indium that I dissolved from heat spreaders but I left the beaker too long and copper started to dissolve too. Now I have an indium and copper chloride mess in that beaker.  

I'm wondering if selective plating at a specific voltage could be used to separate the metals.
There is a measurement method for identifying metals in solutions called voltammetry where metals are plated out at specific potentials.

I'm not interested in it for the money but for the joy of recovering and refining that metal myself. 8) 

Göran


----------



## solar_plasma (Apr 18, 2014)

Just guessing.....testing free of silver and gold to avoid the formation of dangerous compounds, precipitating everything as hydroxides or maybe phoshates and redissolving copper with NH4OH? :?:


----------



## g_axelsson (Apr 30, 2014)

It seemed to work quite good to selectively plating out each metal. It started producing copper powder, then it begun to plate a lead grayish powder that I suspect was the indium.
This was just a test with two carbon electrodes and a regulated power supply. To make it a more viable process the voltage and current should be controlled better to only plate copper in the first step. It would also have been good with some agitation to keep the solution moving past the electrodes and avoiding local depletion.

I just went on and plated out all the metals from the solution so now I have a mixture of indium and copper powders. I'm going to melt it together into a blob of metal and then try to make an indium refining cell some time.

But my conclusion is that electrowinning at a specific voltage could extract a large part of one metal at a time from a mixed solution.

Göran


----------



## butcher (May 1, 2014)

Indium being above hydrogen in the reactivity series, indium will dissolve in HCl.
The copper metal being below hydrogen in the reactivity series will not replace hydrogen or dissolve in HCl without an oxidizer.

With the copper being reduced to metal powders, I think I would try HCl.


----------



## g_axelsson (May 1, 2014)

Indium dissolves slowly in HCl (according to literature) and copper powder easily oxidizes in powder form and the copper oxide is dissolved in HCl. Even if I don't dissolve any copper I still have to turn it back into metal again, either by cementing with zinc or electrowinning, any copper dissolved would contaminate my final product.

In an electrolytic refining cell (both chloride or sulfate system could be used) the copper should drop as anode sludge and I would get metallic indium directly. By rerunning the indium I would get higher purity with the same setup.

... and I also want to test the electrolytic cell with indium just for fun. :mrgreen: 

ref:
Preparation of high-purity indium by electrorefining (pdf), ZHOU Zhrhua, MO Hong-bing and ZENG Dong-ming, Trans. Nonferrous Met. Soc. China (2004)
Processing of indium: a review (pdf), Alfantazi and Moskalyk, Minerals Engineering 16 (2003) pg. 687–694

Göran


----------



## solar_plasma (May 1, 2014)

Maybe a pretreatment could save time: 
Fe3+ is precipitated quatitively as hydroxide at pH3,5 1 (ofcourse all iron(II) needs to be oxidized to iron(III) frist - chlorine would do that.If the AR has been treated with reducing agents, the iron probably has been reduced to oxstage II, too)
NH4OH will precipitate indium and in excess NH3 both copper and nickel will stay in solution as complexes, while indium won't 2,3

Ref.:
1 http://tu-dresden.de/die_tu_dresden...wesen/ifw/lehre/V5 - Schwermetallfaellung.pdf
2 http://books.google.de/books?id=ViO...e&q=precipitation of indium hydroxide&f=false
3 wiki/Nickel(II)hydroxide, copper(II)hydroxide



> from heat spreaders but I left the beaker too long and copper started to dissolve too. Now I have an indium and copper chloride mess in that beaker.



if it is only indium and copper (and traces of nickel), this should even be easier to separate


----------

