Preparation and properties of endothermic functional ceramics with iron tailings as raw materials

Abstract

The present work attempts to utilize iron tailings as the main raw materials for preparation of functional ceramics as a means of resource utilization. A new type of endothermic functional ceramics, which can be used in the field of solar energy, was prepared via semi-dry pressing followed by pressureless sintering. The results show that the functional ceramics made of 68 wt% iron tailings, 26 wt% iron ore, 3 wt% alumina, 1 wt% potash feldspar and 2 wt% kaolin, sintered at 1185°C exhibited the best overall performance. Visual observation reveals that there were no cracks on the surface of the samples even after 20 cycles of intense thermal shock. Other attributes could be summarized as follows: Infrared emissivity in mid-infrared region: 0.85; thermal conductivity at 500°C: 2.066 W/ (m·K); flexural strength: 119.03 MPa. XRD analysis indicates that the main crystalline phases in the samples are augite, magnetite and a small amount of hematite. An increase in the proportion of iron oxide contributed to lower melting temperature of the functional ceramics, deepen color, promote densification and increase infrared emissivity. In short, the introduction of iron tailings improves the thermal and physical properties to a certain extent.

Preparation and performance of solid thermal energy storage materials based on low-grade pyrophyllite minerals

“…In general, the thermal energy storage per unit volume increases with the increase of sintering temperatures. It is mainly because the higher sintering temperature is beneficial to the compactness of the samples, so the specific and bulk density is relatively high [ 23 ]. According to the above experiment results, when the sintering temperature is 1200 °C, the thermal properties of the solid thermal energy storage material are optimum.…”

“…Now, low-grade tailings have more than 8 billion tons [ 11 ], and can't be effectively utilized. Some researchers proposed to prepare functional endothermic materials with iron tailing and bauxite tailings [ 23 , 24 ]. Pyrophyllite minerals account for 70% of the world in China, and their main compositions are SiO 2 and Al 2 O 3 [ 25 ].…”

­Effect of sintering treatment time on the sintering behaviour and thermal shock resistance of Li2O-Al2O3-SiO2 glass-ceramics

“…The poor conduction of heat by the trapped air in the pores restricts the ability of atoms in glass- ceramic to conduct heat. Hence, a lower percentage of porosity can enhance thermal conductivity [51,52]. The lowest thermal conductivity of A3_4 was due to the greater porosity obtained amongst the other samples.…”