Recycling of low-silicate iron tailings in the production of lightweight building materials

作者：Chen, Yongliang^*; Chen, Junbao; Du, Jianhua; Chen, Tiejun; Wang, Xuedong; Ren, Dajun

来源：Journal of Material Cycles and Waste Management, 2022, 24(2): 506-516.

DOI：10.1007/s10163-021-01336-y

• Low-silicate iron tailings
• Lightweight building materials
• Bentonite
• Perlite
• Feldspar

A feasible process for preparing lightweight building materials from the low-silicate iron tailings was developed. Various proportions of bentonite, expanded perlite and feldspar were mixed into iron tailings to serve as binder, pore former and fluxing agent, respectively. The effects of blending ratios of raw materials and firing temperatures on the final product's properties were investigated in laboratory-scale trials. It was found that the optimal ratios of materials were 46 wt.% iron tailings, 19 wt.% bentonite, 25 wt.% expanded perlite and 10 wt.% feldspar. The best firing temperature was 900 degrees C. The properties of the new material were: bulk density 0.90 g cm(-3); compressive strength 8.5 MPa; apparent porosity 42.96%; and thermal conductivity coefficient 0.222 W/(m center dot K), all meeting Chinese Standard Specifications for Fired Heat Preservation Brick and Block (GB 26538-2011) for MU7.5 bricks. The phase compositions and microstructure of the material specimens were analyzed by XRD and SEM, showing that the main mineral phases in the materials were quartz, hematite, mullite, anorthite, microcline and albite. The internal structure contained adequate micropores, which contributed to the mechanical properties and lightweight index of the final product.