Study Of The Steel Slag-red Mud Glass-ceramic

With the rapid development of steel industry and aluminium industry, a large amount of steel slags and red mud slag mountains of red mud were thrown away to form slag mountains in steelmaking and extracting alumina process, which not only occupied a lot of land, but also caused serious environmental pollution. In recent years, how to effectively use steel slag and red mud has become a hot research topic. In this thesis, steel slag and red mud were innovatively used as main raw materials, and melting method was adopted, in the absence of nucleation agent and flux, the formula and heat treatment process were optimized to prepare red mud steel slag glass-ceramic with excellent performances and achieve the dual benefits of society and economic.In the experiment, total content of steel slag and red mud was designed as90%, in which the percentage of steel slag was40%,45%,50%,55%and60%, respectively. THe heat treatment process of basic glass was determined by differential thermal analysis, XRD and SEM were adopted after heat treatment to analyze the phase composition and microstructure of glass ceramics. Effects of steel content of slag red and red mud, and heat treatment temperature on the physical and chemical properties of glass ceramics were studied, and the changes of the physical and chemical properties were discussed. Finally, the optimal proportion of the red mud-steel slag glass ceramics and heat treatment temperature were obtained.The results showed that, the phases of glass ceramics had never changed with the variation of steel slag and red mud content. The main crystal phase is gehlenite, and the second phase was calcium iron diopside. With the increase of steel slag, gehlenite phase increased gradually, calcium iron diopside phase gradually reduced; as for the microstructure, the crystals precipitated were granularor lump shaped, from0.2tolμm. With the addition of steel slag, the grain size and density gradually increased. However, with excessive steel slag, microcracks and holes appeared in glass ceramics, which affected its properties. With the increases of steel slag addition, its mechanical properties increased firstly and then decreased, and the chemical stability improved gradually. When the dosage of steel slag was50%, the density of the glass ceramics was preferable, and the mechanical properties was optimal, with flexural strength of161.57MPa and the microhardness of839.5MPa.In this paper, glass ceramics prepared by50%steel slag and40%red mud was significantly discussed for the influence of heat treatment temperature on the phase compositions, microstructure and various physical and chemical properties. Variation of nucleation temperature did not change the main crystalline phase, while crystalline phase of the samples changed with the variation of nucleation temperature, the calcium iron diopside changed into gehlenite, it’s easier to precipitate gehlenite phase at high crystallization temperature. With the rises of nucleation and crystallization temperature, the nucleation and growth process of glass ceramics was completed gradually, and the grain density became more uniform. However, higher heat treatment temperature would cause accumulation of coarse grains, and defects of cracks and holes appeared in glass ceramics matrix, which affected its properties. Flexural strength increased with the rise of nucleation temperature, and along with the increase of crystallization temperature it showed a trend of decrease after the first increase. The higher the heat treatment temperature, the more stable the chemical durability of the glass ceramics. When steel slag content was50%andred mud content was40%, the optimal heat treatment temperatures were:the nucleation temperature of770℃, the crystallization temperature of870℃.