Upcycling Waste Mineral Wool into Ambient Pressure-Dried Silica Aerogels

This study presents a novel method for upcycling waste mineral wool into silica aerogels synthesized via the ambient pressure drying method. Mineral wool is a widely used insulation material that is commonly landfilled rather than recycled. Prior research investigated alternative applications of waste mineral wool as an aggregate in various industries, such as cement production or ceramics manufacturing. Due to its high amorphous silica content, it can serve as a raw material for silica aerogels. Aerogels are outstanding insulation materials due to their unique properties, such as low thermal conductivity and density, high surface area and porosity, and innate fire retardancy. However, the current high price of aerogels hinders their use on large scales, partly due to the embedded production costs, such as raw materials and the energy-intensive drying process. To address this, a cost-effective production route using waste materials is explored, thereby reducing waste and promoting sustainability. The extraction of silica is optimized based on efficiency and practical scalability at the industrial level. Several waste samples, which have different degrees of pollution from demolition waste, are tested to determine the effect of common contaminants on the silica extraction efficiency. The resulting aerogels are hydrophobic and have a thermal conductivity of 22-26 mW m^-1 K^-1, a specific surface area of 603-676 m²/g, and a density of 86-136 kg/m³. This research demonstrates a novel approach for silica extraction from mineral wool waste, accounting for demolition-related impurities, and offers insights into sustainable waste management practices.