Sciencemadness Discussion Board

High temperature 'incineration' of smartphones and e-waste ?

metalresearcher - 6-5-2017 at 08:55

A smartphone contains at least half of all 83 natural occurring elements.
Currently most e-waste goes to some African countries or India where people and even children are working with dangerous chemicals without any protection and all fumes are just dumped into the ambient air.

http://www.compoundchem.com/wp-content/uploads/2014/02/The-C...

I think that high temperature incinerating old smartphones (and e-waste in general) can reclaim the metals.
Putting the e-waste in an electic arc in an inert atmosphere, which temperature is over 3000 C, will result the waste to vaporize, all more complex compounds like plastics will decompose to simple hydrocarbons and other simple compounds like CO. Most of the metals will vaporize, except the highest melting ones like W, Ta (the latter from capacitors) and can be condensed in a fractional way which can reclaim the Li of the battery almost in a pure state due to its relatively low boiling point.
The precious metal remains, which comprise mostly of Cu (wiring) and soms Ag and Au (contacts), can be separated by electrolysis which already happens with such waste. Only metals like In and Sn (from the touchscreen) and Al (iPhone body) are a bit harder to reclaim I think.
Ceramic materials (glass of the screen, etc) just float as a slag on the metallic remains.

This way can be environmentally friendly, as no noxious gases are generated because these toxic gases are all decomposed at such temperatures.

Can this be a feasible way ?

NWS - 6-5-2017 at 09:58

I would recommend looking at chemical extraction first. The material used in circuit boards can contain chlorine and bromine(see FR-4 https://en.m.wikipedia.org/wiki/FR-4 ) , and there may be other plastics present which could produce under anoxic or reducing conditions some pretty nasty stuff like dioxins. You won't get CO without a source of oxygen.

[Edited on 6-5-2017 by NWS]

metalresearcher - 6-5-2017 at 12:34

Quote: Originally posted by NWS  
I would recommend looking at chemical extraction first. The material used in circuit boards can contain chlorine and bromine(see FR-4 https://en.m.wikipedia.org/wiki/FR-4 ) , and there may be other plastics present which could produce under anoxic or reducing conditions some pretty nasty stuff like dioxins. You won't get CO without a source of oxygen.

[Edited on 6-5-2017 by NWS]

That is exactly what I mean: at such high temperatures as in an electric arc (3000 C) dioxins decompose to harmless compounds. Maybe some HCl/HBr but that can easily be captured with water.

macckone - 6-5-2017 at 20:19

Incineration at those temperatures is not cost effective.
Which is why chemical extraction methods are used.
Crush it up, float the plastic bits, Dissolve the remaining
bits in acid solution then electrolize it. The crushing and
flotation use almost no energy to speak of. Flotation and
electrolysis is also used to clean up heavy metal contaminated
soil in remediation efforts.