The potential of SiO₂ obtained from pyrite slag: Used in the fabrication of SiO₂/graphite glass ceramic with pronounced capacity for electromagnetic wave absorption

The rapid development of electronic devices is increasing electromagnetic pollution, raising demand for efficient electromagnetic wave absorption materials in commercial applications. Low-cost SiO₂/graphite glass ceramics with excellent EMW absorption and load-bearing capacity were fabricated using amorphous SiO₂, recycled from Baihe pyrite slag, showing potential for use as EMW absorbing building exterior walls decoration layer material. The effects of sintering temperature, graphite content, and fluxing agent addition on ceramic preparation were investigated. XRD, SEM, and EDS analyses confirmed phase composition and microstructural evolution during fabrication. Mechanical property of samples showed that adding a small amount of graphite improves crack propagation resistance and enhances mechanical properties, with bending strength of glass ceramics with 10 % graphite adding reached 18.3 MPa. However, further increasing graphite content reduces the material's mechanical properties. The EMW absorption of SiO₂/graphite glass ceramics with varying graphite contents was studied over 2–18 GHz. Optimal performance occurs at 20 % graphite content, achieving a minimum reflection loss (RL_min) of –28.4 dB and an effective absorption bandwidth of 3.4 GHz, due to impedance matching ability. Overall, the 20 % graphite composition offers excellent EMW absorption (RL_min=–28.4 dB) and good mechanical strength. The use of SiO₂ derived from Baihe pyrite slag to fabricate EMW absorbable glass ceramics enables tailings recycling, reduces environmental pollution, and lowers production costs for load-bearing EMW absorbing materials, supporting economic circularity.