Insight into the Microstructural Evolution and Fluorine Migration Mechanism of Lightweight Ceramsite Derived from Fluorite Tailings

Abstract

Fluorite tailings (FT), derived from fluorite flotation processes, are predominantly disposed of in landfills across China, leading to resource wastage and environmental contamination. This study focuses on the preparation of ceramsite from FT via a pelletizing and sintering process. The effects of materials addition ratio, sintering condition on the physical properties of the ceramsite were systematically investigated. Utilizing FTIR, XRD, SEM and industrial CT, the evolution of phase and microstructures receives a systematic examination. The results reveal that ceramsite properties influenced by feldspar content, pyroplastic mass fraction and internal foaming behavior during sintering. The resulting ceramsite exhibits a high compressive strength of 4.63MPa, a water absorption rate of 0.21%, and an apparent density of 0.890g/cm3. Moreover, the ceramsite matrix encapsulates stable F-containing compounds like CaF2, facilitating F-ion immobilization within the structure. The incorporation of FT in ceramsite production represents a pragmatic strategy for mitigating the adverse impacts of FT disposal.

Keywords: fluorite tailings, lightweight ceramsite, microstructural evolution, fluoride ion immobilization, physical properties