A Random Thought on how to Recover Indium

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darinventions

Well-known member
Joined
Jan 10, 2015
Messages
98
So I’ve been reading different threads on recovering Indium out of LCD screens...Everything I’ve read so far leads to recovering everything but the Indium,,, So this left me with one question,, HOW CAN I GET THE INDIUM OUT? Most all of us have had to come up with some way to dispose of these pesky screens that you can’t do anything with,, an is not economically feasible to recover the Indium out of unless you have tons of them,,not to mention all the waste byproduct produced dealing with the liquid crystal inside of them... So I had a IDEA....And please share your thoughts,,,I’m under the impression that when Indium melts, that it like most other metals will bead up and bond with one another,,So if you were to crush them up, place inside a steel drum with a lid removing the plug in the lid of course,covering all the broken material with a high temperature oil like cooking oil,and building a bonfire around it if that would work for extracting the Indium,,and simply saving the oil for another extraction later on? Now before someone has a fit about this possible method I should add that I have no idea about the liquid crystal in the screens,, so take it easy on me,, as far as the glass,i know of a few places that take all glass no matter what condition as long as it’s not leaded TV glass...And I will add that I’ve got about 5 acres of empty land to do this on if it’s a feasible idea..
 
It isn't metal, it is in the form of an oxide.

http://goldrefiningwiki.com/mediawiki/index.php/LCD
A mixture of indium and tin oxides are used and sits on the inside of the glass sheets. The amount of indium used in a screen is tiny, about 0.01% of the weight of the glass. (0.1g / kg) The liquid crystal is a mixture of 10 to 25 different compounds and are highly toxic to the environment. It can be dissolved in a solution of 17% (vol%) isopropyl alcohol assisted by ultrasonic.
There are some references that might be interesting at the end of the article.

Göran
 
Very Well Answered Sir,,, so attempting to recover any amount of Indium from LCD screens of ALL types is a waste of time and effort,,With that said anyone who obtains these screens are better off to try their best to leave them intact an sell or give them to a recycler that has the proper equipment to deal with this type of scrap..
 
To effectively recover indium and tin from LCD-screens requires tons of material, specialized equipment and good waste treatment.
Actually, I don't know if there is anyone recovering indium from LCD-screens yet. A quick googling turned up a number of research papers but no refinery saying they do recover indium.

Göran
 
There are several large integrated smelting operations that recover indium. Originally they recovered indium as a byproduct of other metal recovery (zinc, copper) but they all now treat e-waste as well.

For example, Teck (formerly Cominco) Trail Operations in BC treat indium-rich waste and e-waste through slag fuming furnaces (reductive coal-oxygen fired tuyere furnacse). This makes a fume (dust) containing lead, zinc, indium, cadmium and other volatile metals.

The fume is slurried, dehalogenated, slurried again and leached with sulfuric acid. Indium is precipitated via pH bump as a preconcentrate. The preconcentrate is reductively leached in stronger sulfuric acid. Indium is removed from leachate via solvent extraction. The pregnant strip solution is "sponged" - metallic zinc is used to cement indium. The sponge is releached and indium is electrowon. The cathodes are melted and the melt is purified via some chemical additions to oxidize impurities to a dross. Indium sticks are cast and sold.

That is the short version. I skipped a lot of the little steps (there are a lot of filtration steps in there, for example).

Umicore (Union Miniere) recovers indium in Belgium via copper and zinc circuits. Their process is actually a little more convoluted than Teck's. They make a lot more indium products as a result, including ultra-high purity, indium alloys and if memory serves indium compounds like indium tin oxide.

There were also two primary copper smelters in Ontario and Quebec that made indium-rich byproducts for further refining. One was shut down a while ago since a lot of the e-waste they were treating was contaminated with beryllium. I don't know the current status.

The large smelting operations don't just treat e-waste. It is a tiny input compared to primary scraps, battery paste, plates and of course mineral concentrates (lead con, zinc con or copper con).

If I were to try to recover indium from screens, I would try a pyrometallurgical circuit, since the indium is "trapped" in a glass matrix, and so very dilute. I would just sell the impure product to a refinery somewhere. I don't think a furnace (and ventilation) just for e-waste treatment would be economically viable, but I may be wrong. Direct hydrometallurgical routes would be even more costly (fine grinding, lots of acid, precipitation, releaching, solvent extraction, etc. etc. and I would bet still very low recovery). Indium isn't worth enough. Just my $0.02, with a 100% discount for the forum...
 
Thanks for that Geraldo

One thing worth noting is that the majority of refineries keep all these metals for themselves anyway. Anything above gold, silver, copper, Palladium, Platinum goes into their pocket as their "bonus."

If I could find a refinery who paid out on a wider range of metals I would be looking to have a serious chat with them because it galls me how much "bonus" they are making over and above their published charges and it can run into thousands of dollars per tonne on certain equipment.

Jon
 
I agree with Jon, thanks Geraldo. That was a quite thoroughly description of the market today.

The only common source where it would be even feasible to recover indium for an amateur would be from the solder used to fasten the heat spreader to the CPU chip on modern CPU:s. I've tried to recover indium that way and I managed to get some, but only sub-gram amounts via wet chemistry methods. My losses were quite large and I need to study the chemistry of indium more.

Göran
 
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