Preparation and mechanism of Fe2O3-based calcium feldspar porous ceramics by direct foaming method using iron tailings

This study develops a feasible process for preparing Fe 2 O 3 -based calcium feldspar porous ceramics (FCPC) from industrial waste iron tailings via a direct foaming method, together with conventional ceramic raw materials of quartz and kaolin, and silicon carbide (SiC) as a foaming agent. The effects of iron tailings content and foaming agent content on the properties and microstructure of FCPC were investigated. It was found that the optimal ratios of materials were 40 wt% iron tailings, 40 wt% quartz, 20 wt% kaolin, and 0.6 wt% SiC, the firing temperature was significantly reduced to 1160 °C. The obtained FCPC demonstrated excellent overall performance, featuring a high apparent porosity of 79.22 %, a low bulk density of 0.49 g/cm 3 , compressive strength of 3.53 MPa, and thermal conductivity of 0.1361 W/(m·K). The phase analysis revealed the presence of quartz, anorthite, hematite, hercynite, ferrosilite, and cristobalite as the main crystalline phases. The outstanding properties of FCPC were attributed to its unique microporous architecture, pore size distribution, and phase composition, with both the iron tailings content and SiC addition playing critical roles in regulating microstructure, porosity, and mechanical strength. Iron tailings acting as both the primary raw material and functional flux were responsible for reducing sintering temperature, SiC addition played a crucial role in raising high porosity and reducing bulk density of FCPC, and iron tailings as auxiliary foaming agent improved SiC fully oxidation. Overall, this work proposes an attractive low-temperature rapid sintering method for the fabrication of high-performance FCPC using iron tailings as the main raw material, establishes a rapid, low-cost, and energy-efficient pathway for the sustainable production of porous ceramics.