Study On Glass-Ceramics Prepared By Recycling Blast Slag

With the rapid development of industry, plenty of slag is ejected into environment. The blast slag is a waste which is emitted in large quantities in metallurgical industry. And it is also a valuable renewable resource. At present, the majority of blast slag is used as a raw material for slag cement. But it is not the most effective way, and it can not reach the requirements of saving energy, reducing emission and saving resource.The blast slag is mostly composed of CaO,Al2O3和SiO2,which are the important component of the CaO-Al2O3-MgO-SiO2 System glass-ceramics. Furthermore, Fe2O3(FeO) in the blast slag is an effective nucleation agent in the glass-ceramics system. So it is a new, effective way to prepare glass-ceramics materials by using the blast slag. It is the great significance for improving the utilization of steel slag, increasing the economic efficiency of enterprises and reducing the environmental pollution.In this paper, the glass-ceramics of CaO-MgO-Al2O3-SiO2 system had been initially prepared by direct sintering method using the blast slag produced by a certain steel corporation in Yunnan province and wasted glass. The major crystalline of the glass-ceramics was diopside (CaMgSi2O6). DSC was used to ascertain the heat-treatment temperature system, and XRD to characterize the phase composition. The effect of forming pressure, heat-treatment parameters and the content of the blast slag in raw material was discussed.In this paper, the sample was suppressed by semi-dry molding method. Along with the increase of the forming pressure, the properties of the glass-ceramics also changed. Through research, the pressure was changed between 110MPa and 150MPa. And along with the increase of the forming pressure, the performance of the glass-ceramics also was improved. It is faster to improve the performance of the glass-ceramics when the forming pressure increased from 110MPa to 130MPa than increasing from 130MPa to 150MPa. Taking into account the die life and energy consumption, not the greater pressure was the better, but we should choose the best points. Taking all factors, we determined that the pressure was 130MPa.Along with the increase of the content of the blast slag, the content of the crystal phase in the glass-ceramics was different, or even was changed. When the content of the blast slag was 35wt%, the major crystalline of the glass-ceramics was diopside (CaMgSi2O6). And when the content of the blast slag was 55wt%, the major crystalline of the glass-ceramics was akermanite (Ca2MgSi2O7). Along with the increase of the content of the blast slag, the properties of glass-ceramics were different. When the content of the blast slag was 35wt%, the properties of glass-ceramics were best. However, the utilization of blast slag was low. For meeting the performance requirements of glass-ceramics and maximizing the utilization of blast slag, we the content of the blast slag was 45wt%.The properties of the glass-ceramics can also be promoted by optimizing the heat-treatment parameters. The optimal heat-treatment parameters in this paper are: nucleated at 750℃for 1.5h, then crystallized at 880℃for 2.5h. The proper rate for heating is:5～10℃/min.