Biomass ashes as potential raw materials for mineral wool manufacture: initial studies of glass structure and chemistry

The energy intensive and CO2-generating nature of commercial mineral wool and glass production necessitates advances and changes in materials and processes. The derivation of raw materials from waste products arising from biomass energy generation offers the possibility of a two-fold environmental benefit: partial replacement of carbonate raw minerals in production, leading to lower CO2 release during melting; and the utilisation and valorisation of byproducts which may otherwise be sent to landfill. Glass samples with a basaltic mineral wool composition were produced with additions to the raw materials of 0, 1, 5 and 10 wt% of a fly ash and a bottom ash arising from biomass combustion. The resulting glasses were analysed by x-ray fluorescence, x-ray diffraction, dilatometry, 57Fe Mössbauer and Raman spectroscopies, and their densities, molar volumes and viscosity–temperature profiles were calculated and compared against benchmark glass samples. All biomass ash-containing glasses were closely similar in both composition and properties to the benchmark glass, with up to 10 wt% ash additions to the raw materials. In addition, the use of the biomass fly ash led to a reduction in batch CO2 content estimated to be 1·5 kg CO2 per tonne of batch for each 1 wt% addition. These initial results provide evidence supporting the further development of these ash materials as potential value-added raw materials for mineral wool manufacture.