Introduction Extracted Titanium slag is a type of industrial solid waste produced when titanium is recovered from titanium-containing blast furnace slag using the high-temperature carbonization-low-temperature selective chlorination method.Currently, it can only be disposed of through simple stockpiling and burial, which endangers both the environment and human health.The use of titanium slag to prepare microcrystalline glass with excellent physical and chemical properties is of great significance for the utilization of solid waste resources and the improvement of environmental pollution. Raw material components and heat treatment systems have a significant impact on the microstructure and mechanical properties of glass ceramics. The current work is based on the chemical composition of titanium slag. high-performance glass?ceramics were prepared by melting sintering method by adding quartz tailings to increase SiO2 content. Our study examines how the acidity coefficient (Mk) and sintering temperature affect the crystallization, microstructure, physical and chemical properties of microcrystalline glass. Additionally, we reveal the composition of the physical phase of glass ceramics made from titanium slag and the evolution of crystallization. These findings provide a technical foundation for the synergistic treatment of various solid wastes in the preparation of glass ceramics.
Methods Titanium slag and quartz tailings were prepared, combined, ball milled, and sieved accordingly. The required raw materials were weighed exactly, put into a corundum crucible, heated untill the glass liquid melted and clarified. The liquid was then quickly dumped into water, to form glass particles, following a procedure of drying, ball milling, and sieving. The basic glass powder and PVA solution were uniformly mixed before being placed in a press-bar mold and pressed into blank samples, which were then sintered to produce glass ceramics sheet samples.The chemical composition of the raw materials was evaluated using X-ray fluorescence spectrometry. A thermal analyzer was used to perform the DSC analysis simultaneously. An X-ray diffractometer was used to conduct physical phase analysis on raw materials and glass ceramics samples. The microstructure of the glass ceramics samples was observed using a scanning electron microscope (SEM), and their microscopic composition was analyzed using an energy dispersive-X-ray spectrometer (EDS).According to the principle of Archimedes, the bulk density and water absorption of each glass?ceramic sample were measured.The bending strength of glass?ceramics was tested by GB/T4741—1999 three-point bending method. JC/T 2097—2011 industrial microcrystalline plate was used to test the acid etching amount of microcrystalline glass.
Results and discussion The morphology investigation reveals that the samples' sintering or fusing steadily improves with an increase in Mk under the same temperature settings. At point of Mk=2.4, the sample begins to soften and distort, whereas at Mk =2.7, it looks to froth.The XRD spectra of the glass ceramics samples demonstrate that the type and amount of the early crystalline phases vary when the Mand sintering temperature increases. Increasing the heat treatment temperature enhances the intensity of the diffraction peaks of the crystalline phases in low Mk glass ceramics samples. At the same sintering temperature, the content of anorthite in glass ceramics samples rises with increasing Mk, while the content of diopside increases in low Mk and decreases in high Mk.The surface and cross-section micro-morphology of the glass ceramics samples demonstrates that the sintering temperature is too low and the materials do not attain the sintered state at lower temperature. With the same Mk, the number of holes in the samples decreases with increasing sintering temperature. As the sintering temperature rises, big closed holes become easier to develop.The features of the glass ceramics samples, together with the results of XRD spectra and SEM analysis, show that Flexural strength and bulk density are mainly related to the type of crystalline phase, crystal content, and appropriately increase the sintering temperature. Mk is conducive to the growth of tremolite and calcium feldspar crystals in the billet, and it also benefits exclusion of porosity, so that the glass ceramics can form a flatter surface, and show higher mechanical-strength, thus to improve the sample's densification, flexural strength, acid resistance, and reduce water absorption as well. At higher acidity coefficients, increasing the SiO2 content in the base glass causes an increase of the liquid phase, which is beneficial for filling pores, reducing the water absorption capacity of glass ceramics, and improving corrosion resistance under acidic conditions.
Conclusions With the increase of Mk and sintering temperature, the type and quantity of crystalline phases of glass ceramics samples will undergo high-temperature physical phase reconstruction. Within a certain temperature range, the increase of sintering temperature can promote the growth of crystals in glass ceramics and the intensity of the diffraction peaks of crystalline phases. However, there exists a moderate temperature, above which the transformation of the crystalline phase shows different behavior, that is, low Mk favors the growth of diopside in glass ceramics, while high Mk promotes the formation of anorthite. When the Mk and the sintering temperature are both low, the glass ceramics samples are not completely sintered. This conditions for crystal growth and exclusion of pores are not sufficient. When the Mk and the sintering temperature increase simultaneously, the liquid phase appears in the matrix, which benefits the growth procedure of crystals to form a fixed crystal skeleton. When the sintering temperature is too high or the Mk is too high, the glass matrix begins to melt, and the phenomenon of overcooking occurs, which leads to an increase in the glassy phase and the expansion of pores, resulting in a strong and solid crystal skeleton. The expansion of pores makes the disjointed circular pores in the glass ceramics samples gradually increase. At Mk =1.5 and sintering temperature of 1 190 ℃, the produced material shows a water absorption rate of 0.07%, bulk density of 3.05 g/cm3, acid resistance of 96.6%, flexural strength of 144 MPa, which fully meet the requirements of industrial glass ceramics panels.