Unhydrated aminopropyl triethoxysilane was used to modify calcined kaolin produced from coal-bearing kaolinite. The aim was to develop a simple and economic modification method without the need for solution immersion and subsequent wastewater treatment. The samples before and after modification were tested using multiple methods, such as XRD, MAS-NMR, FT-IR, XPS, and SEM. The study results indicate that this modification can effectively improve the surface property of calcined kaolin. The activity index increased to 76.7% when the modifier usage was 2%. With a further increase in the modifier content, the activity index decreased. Surface modification did not reduce the whiteness of calcined kaolin. Further, the modification reaction mechanism was elucidated. Based on the detailed analyses, it was found that the modification reaction took place between the NH₂ groups in the modifier molecules and Al^VI-OH in calcined kaolin, and hydrogen bonds were formed between the NH₂ groups and the active sites on the calcined kaolin surface.

Compared to basalt and glass fibers, the production of inorganic fiber from industry solid wastes is an effective method to not only save natural resources but also recycle waste resources. Because the preparation of the fibers requires high temperature treatment, the production process is associated with high energy consumption and high carbon emissions. How to resolve these problems is a current research challenge in this field. Herein, we reviewed the study progress on these fibers and further discussed the key factors determining their characteristics, including chemical composition, melt structure, and viscosity of melt. In production, the matching of solid waste blends containing enough total content of SiO₂ and Al₂O₃, and a suitable amount of MgO and CaO, is beneficial to the structure control of the melt. The study found that the melt consisted of Q² and Q³; and that Q³ content more than Q² was more suitable for fiber production and its performance improvement. Such a melt structure can be achieved by controlling the degree of depolymerization and the temperature. New ultrasonic technology can shorten the homogenization time; its application is hoped to save energy and reduce carbon emissions. These conclusions will offer important guidance for the development of inorganic fibers from industry solid wastes in the future.

Calcium carbide slag is a highly alkaline solid waste generated during acetylene production, but its long-term accumulation causes land occupation and persistent environmental risks such as soil alkalinization and water pollution. To support circular economy and carbon emission reduction goals, in this study, we develop an integrated physical decontamination–mineralization process combining calcination, magnetic separation, sedimentation, and CO₂ mineralization. After calcination, magnetic separation, and 8 h of gravity sedimentation, the removal efficiency of Si reaches about 67% (residual Si content reduces to 0.43%), while those of Fe and Al are 75.4% and 74.2%, respectively. The purified calcium-rich slurry is then used for CO₂ mineralization. Under a solid-to-liquid ratio of 10% and a CO₂ flow rate of 0.4 L/min, CO₂ is fixed as carbonate solids, yielding calcite-type CaCO₃ with 97.88% ± 0.35% purity. This process is centered on physical separation and uses no acids, alkalis, or ammonium salts, avoiding secondary pollution while achieving waste valorization and permanent CO₂ sequestration. In this study, we provide a scalable, low-impact pathway for alkaline solid waste valorization and carbon emission reduction, contributing to sustainable consumption and production (SDG 12) and climate action (SDG 13).