I know I have read over the years on this forum that GaA'a are recyclable, in that the chip can be melted down (?) and used again, whereas with silicon, this is not possible. I can't find a link but the info must have come from oogee or fj, if I remember correctly. So additionally, yes, it has been spoken of here (or SH before here), although honestly I can't remember what the final conclusion was other than it was good enough for me.

Edit:

A coupleof links regarding recycling:

http://www.appropedia.org/Semiconductor_recycling_plant_case_study_of_GaAs_photovoltaic_manufacturing

http://www.waferworld.com/gaas-inp-reclaim