A fluidised-bed process for the recovery of glass fibres from scrap thermoset composites

A fluidised bed combustion process was developed for the treatment of thermoset composites in the form of process scrap or end-of-life components. The process was shown to be robust, coping with contaminated scrap of variable composition and providing useful outputs in the form of recovered fibres, particulate materials and heat. Comminuted feeds were decomposed at a bed temperature of 450°C and a fluidising velocity of 1.3 m/s. Fibres with mean lengths of up to 5 mm were collected at purities of up to 80% by using a novel rotating sieve separator. Shorter fibres were collected with the particulate mineral fillers. The tensile strength of recovered E-glass fibres was reduced by up to 50% although this depended on the thermal history within the process. Fibre modulus was relatively unaffected by the exposure to high temperatures. Recovered fibres were successfully reused in DMC formulations and veil products. A simple economic model suggests that the process would break even at a throughput of approximately 9000 tonnes scrap composite per year.