Upcycling petrochemical industry incinerator slag and waste glass into lightweight ceramic foam glass

The incineration of different industrial waste significantly reduces its volume but produces substantial amounts of fly ash and bottom ash, collectively termed Industrial Waste Incinerator Slags (IWIS), which pose serious environmental risks if not properly managed. This study investigates the sustainable reuse of IWIS obtained from a petrochemical refinery in Hungary as a secondary raw material to produce ceramic foam glass (CFG). Waste bottle glass (BG) was combined with varying proportions of IWIS, while silicon carbide (SiC) served as the foaming agent. The mixtures were compacted using a hydraulic press at 18 MPa and sintered at the temperatures corresponding to the maximum foaming height, determined via heating microscopy. Temperature holding times were varied to evaluate their effect on the sintering behaviour and final properties of the CFG samples. The raw materials and the produced samples were investigated based on mineralogical, chemical, and morphological studies using X-ray diffraction (XRD) and X-ray fluorescence (XRF) to evaluate phase composition and elemental distribution. A comprehensive analysis of technical properties, including compressive strength, water absorption, bulk density, and thermal conductivity, was conducted to assess the influence of IWIS and SiC on the performance of the CFG. Water absorption ranged from 0.85 to 32.39 %, thermal conductivity varied between 0.11 and 0.85 W/m·K, and bulk density ranged from 0.58 to 2.25 g/cm³, indicating a wide tunability of properties based on processing conditions. These findings demonstrate the technical feasibility of utilizing petrochemical IWIS into glass–ceramic foams with competitive thermal insulation performance for non-load-bearing construction applications.