Glass fibre recycling from wind turbine blade waste using ball milling method

Abstract

A large share of the wind turbine blades being decommissioned have been made of glass fibre-reinforced polymer (GFRP) which is a composite made of glass fibres encased within a thermoset resin. It is increasingly challenging to dispose of these huge composite constructions environmentally and logistically, and this encourages the design of scalable recycling lines that could produce reusable secondary raw materials. The traditional ways of GFRP recycling (like pyrolysis or chemical treatment) are capable of recovering relatively clean fibres however, these are energy-consuming, and need dangerous processing conditions, so their recyclability in the industry is limited.

In this paper, the research proposal deals with an arid mechanical recycling process where wind turbine blade GFRP offcuts are milled in a planetary ball mill, and centrifugal heavy-liquid separation is conducted to separate the glass fibre fraction. The paper narrows down on the effect of the four important operating variables such as milling time, rotational speed, ball to powder ratio (BPR) and grinding ball diameter on the yield of powder, purity of the glass fibre and the use of energy. A typical particle size of around 12 սm (D90) was achieved and purity of the glass fibre of about 88 89 per cent under the optimised conditions of fine-milling (3 mm zirconia balls, 700 rpm, BPR 6:1, 120 min). Values of degree of liberation to a maximum of 85.5% were recorded in the case of course-grinding with bigger balls. The amount of energy needed to mill the ball was estimated and compared to the literature figures of pyrolysis, chemical recycling and mechanical size reduction.

The findings indicate that by doing high-energy ball milling along with density-based separation, glass-fibre-enriched powders that can be put back into service as fillers or fine-structural reinforcement in cementitious composites and moulding compounds can be obtained at a significantly reduced cost of energy consumption compared with thermal or chemical recycling. The thesis further puts forward the combined performance measure which combines yield, purity and specific energy giving a more relevant optimisation framework in applications compared with the degree of liberation measure.

Date of Award	15 Jul 2026
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Kok Wong (Supervisor) & Nai Yeen Gavin Lai (Supervisor)