Coal gangue, a prevalent solid waste in the coal industry, has long been a significant concern due to its substantial production volume and potential environmental hazards. However, it contains valuable components such as silica and alumina, making it a promising raw material for synthesizing cementitious materials. This study focused on the synthesis of coal gangue-based magnesium silicate hydrate (M-S-H) and calcium silicate hydrate (C-S-H) through mechanical–thermal–chemical composite activation treatment. The cementitious activity of coal gangue samples and the characterization of the resulting cementitious materials were analyzed using ICP-AES, FTIR, XRD, SEM, and DSC-TG. Results indicated that calcination temperature, calcination time, the Ca/Si molar ratio, and the Mg/Si molar ratio were key factors influencing the cementitious activity of coal gangue, exhibiting a positive correlation with the dissolution amounts of Si⁴⁺ and Al³⁺. When kaolin in coal gangue was fully decomposed into active Al₂O₃ and SiO₂, the cementitious activity of coal gangue reached its peak. M-S-H and C-S-H were successfully synthesized after 7 days of curing at room temperature, significantly reducing the synthesis time. The synthesized M-S-H and C-S-H exhibited large specific surface areas, good mechanical properties, and well-developed pore structures, making them suitable as mesoporous materials that provide numerous active sites for adsorbing metal ions.

This study reveals the synergistic effects of Mn and Zr microalloying and equal-channel angular pressing (ECAP) on the microstructure and corrosion behavior of Mg-Y-Zn alloys in Hanks’ solution. At moderate deformation levels (four passes), the alignment of LPSO phases forms semi-continuous barrier structures, promoting the formation of dense corrosion product layers and improving corrosion resistance. (e.g., Mg-Y-Zn-Mn 4p: 1.07 mm·y⁻¹). However, excessive deformation (eight passes) leads to severe fragmentation of LPSO phases, increasing cathodic activity and intensifying micro-galvanic coupling in Mn-containing alloys (Mg-Y-Zn-Mn 8p: 2.61 mm·y⁻¹). In contrast, Zr-containing alloys exhibit continuous improvement in corrosion resistance with increasing ECAP passes, attributed to enhanced electrochemical uniformity resulting from homogeneous ultrafine-grained structures (Mg-Y-Zn-Zr 8p: 0.87 mm·y⁻¹). These findings elucidate the critical mechanism by which the interplay between microalloying chemistry and severe plastic deformation governs electrochemical uniformity and corrosion kinetics. This work provides new insight into the corrosion behavior of ECAP-processed Mg-Y-Zn alloys, highlighting the critical role of balancing microstructural refinement and electrochemical heterogeneity, and offers guidance for the optimization of corrosion-resistant Mg-based materials.

To understand the cause of the high content of phosphorus in the North Chaohu Lake Catchment of China, the distribution of the total phosphorus in groundwater and the dissolution of rock phosphorus near Chaohu Lake were investigated, and a few interesting findings have been revealed. Firstly, four main processes affecting the groundwater quality in North Chaohu Lake Catchment were identified with the results of factor analysis, including anthropogenic activities and the dissolution of carbonate rocks, phosphorus, and fluorine-bearing minerals. Secondly, the dissolution of rock phosphorus can be well described using the one-dimensional diffusion equation, with a semi-infinite boundary condition, and the Langmuir kinetic equation. A relatively low ambient temperature (less than 25 °C) was probably responsible for the small diffusion coefficient compared to that of the previous studies. Thirdly, the high-potential maximum dissolution of rock phosphorus (C_max) indicated that the dissolution of rock phosphorus could pose a risk to the ambient water body, and C_max was found to be independent of the total rock phosphorus content.