Production of Lightweight Fillers from Waste Glass and Paper Sludge Ash

The production of high-performance lightweight fillers (LWFs) using mixed colour recycled glass and paper sludge ash (PSA) has been investigated. PSA has low sintering activity at temperatures below 1200 °C and therefore glass was added to promote liquid-phase sintering. This allows sintering to occur with simultaneous gas evolution from the decomposition of calcium carbonate present in PSA and this results in extensive pore formation and the production of foamed materials. The lightweight porous materials formed are suitable for use as LWFs. Key process parameters including PSA content, particle size of the raw materials and sintering conditions have been optimised. Optimum processing of glass containing 20 wt% PSA at 800 °C produces particles with physical and mechanical properties comparable to leading commercially available LWF products.