Industrial upscaling of waste mineral wool valorisation in the circular economy perspective: Integrating secondary and local raw materials in the European ceramic industry

The transition toward a circular economy requires the ceramic industry to reduce dependence on primary raw materials and integrate secondary resources into established production routes. In this study, the valorisation of waste mineral wool, previously transformed through thermal inertization into a homogeneous glass (named Re. Wo), is scaled up from laboratory validation to pilot-plant production of porcelain stoneware tiles. Unlike previous investigations based on non-European raw materials and laboratory-scale tests, this work employs locally sourced European clays and sands, strengthening supply-chain resilience and environmental coherence. Four formulations were designed, including a benchmark and batches containing 2-6 wt.% Re.Wo as partial replacement of feldspar. After laboratory simulation (TRL 4), selected compositions were processed at pilot scale (TRL 6) using standard ceramic equipment under representative processing conditions for milling, spray drying, pressing, and roller-kiln firing, culminating in the production of a batch of 60 m2 of tiles. Technological properties of unfired and fired bodies, gresification behaviour, phase evolution, and thermal stability were systematically evaluated. The successful pilot-plant production demonstrates the technical feasibility of the process, showing that Re.Wo-bearing formulations up to 4 wt.% can be processed at TRL6 while maintaining technological and mechanical performance comparable to that of the benchmark. A preliminary life cycle assessment (LCA) was conducted to evaluate the environmental implications of Re.Wo incorporation within a prospective industrial scenario. This work provides a pilot-scale proof of feasibility for the integration of inertized hazardous waste into high-value ceramic products, contributing simultaneously to landfill diversion and reduction of critical raw material use.