低濃度クエン酸分解による高炉スラグからの高純度シリカの選択的回収とその乾燥剤としての応用

抄録

Blast furnace slag is generated in large quantities as a by-product of ironmaking and is mainly utilized in bulk applications such as cement production. However, high-value utilization focusing on the functional properties of individual components included in the slag remains insufficient. Using a low-concentration citric acid aqueous solution, selective separation and recovery of silica from blast furnace slag could be performed but some impurities remained. Cation-exchange resin treatment reduced impurity metal ions such as Ca and Mg so effectively that the SiO₂ purity increased to approximately 95%. Water vapor adsorption measurements revealed type-IV isotherms with hysteresis that indicated the development of mesoporous structures. Practical desiccation performance was evaluated under closed vessels in comparison with a commercial silica gel. The recovered silica exhibited moisture adsorption behavior comparable to that of the commercial one and demonstrated its applicability as a desiccant material for humidity control applications. The proposed method enables efficient recovery of functional silica from blast furnace slag under relatively mild conditions and has potential as a sustainable resource-recycling utilization process.