Reuse of volcanic material as a mineral additive in spodumene tailings-based ceramic production: Physical, mechanical, structural, and durability changes

Abstract

Vast amounts of volcanic materials (VM) are produced annually from volcanic eruptions, with the majority being deposited in urban and sub-urban areas due to the lack of legislation regarding its disposal and recycling. To address this issue, this study explores the reuse of VM as a mineral additive in spodumene tailings-based ceramics for construction. In this study, spodumene tailings (QFS) were used as the primary precursor for ceramic production. The effects of QFS milling, VM incorporation, and sintering at different temperatures (950 °C, 1050 °C, and 1150 °C) were investigated through visual observation, compressive strength testing, X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC), scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM-EDS), water absorption and apparent density measurements, freeze–thaw resistance testing, and exposure to sulfuric acid, acetic acid, and combined sulfate and chloride environments. The experimental results demonstrated that milling QFS and incorporating VM as a mineral additive significantly improved the composite ceramics' high-temperature performance. These improvements included reduced voids and cracks along with enhanced residual strength, densification, and durability compared to ceramics produced with unmilled QFS or without VM. The densification and strength gains were primarily attributed to the partial melting of the QFS and VM particles from approximately 1050 °C. At this temperature, the formulation comprising 60 wt% milled QFS and 40 wt% VM achieved a high compressive strength of 45 MPa and a low water absorption rate of 5 %. Furthermore, ceramics containing milled QFS and VM exhibited superior stability after 60 days of exposure to sulfuric acid, acetic acid, and combined sulfate and chloride environments, as well as 120 freeze–thaw cycles in water. The higher stability is attributed to the dual effect of the elevated sintering temperature and VM addition, which together promoted the formation of more stable crystalline phases and a denser ceramic structure.