The resin has a low Tg (temp at which it turns goopy again) - somewhere around 500*F even for 'aerospace' stuff. Whereas recycling aluminum requires roughly double that temperature to begin to melt aluminum.

The carbon fiber is then chopped and used as reinforcement in other material likes plastics. SGL Group, who supplies/partners in production with BMW, even uses reclaimed and production waste in it's production process for the new 7-series.

A more technical breakdown and state of the industry can be found here: http://www.compositesworld.com/articles/recycled-carbon-fibe...