Fabrication and properties of high-thermal-storage RTO ceramics using bauxite tailings and red mud

Abstract

Nowadays, it is critical to find materials and methods that can help reduce the human impact on the environment. Regenerative thermal oxidizers (RTOs) have a wide range of applications owing to their effective energy saving. Among the different RTOs, thermal-storage RTO ceramics have basic heat storage and release capability. The main objective of this work is to study the preparation of thermal-storage RTO ceramics for the treatment of exhaust gas using bauxite tailings and Bayer red mud from Jiaozuo City (Henan Province) with different mass fractions of magnetite as substitutes for the traditional raw materials (quartz and clay). The effect of the magnetite addition on the performance of the thermal-storage RTO ceramics prepared from the bauxite tailings and red mud was investigated. The raw materials were pressed into cylinder shape and then sintered at 950 °C, 1000 °C, 1050 °C, and 1100 °C. The developed materials were analyzed and characterized via X-ray diffraction and scanning electron microscopy, and specific heat capacity tests (differential scanning calorimetry using the sapphire method) were conducted on the thermal-storage RTO ceramics prepared at the optimal sintering temperature (1050 °C). The ceramics exhibit the best overall performance for magnetite content of 25% and sintering temperature of 1050 °C, with compressive strength of 134.96 MPa, volume density of 3.00 g/cm3, and linear shrinkage of 14.68%. The product also has a remarkably low water absorption rate and apparent porosity, water absorption of 0.02%, apparent porosity of 0.06%. Furthermore, the specific heat capacity is sufficiently high to meet the requirements of high-thermal-storage RTO ceramics. This study provides a new, low-cost solution for the preparation of high-thermal-storage RTO ceramics, which is helpful for reducing the exploitation of natural mineral resources.