Study On Crystallization Mechanism Of Coal Ash-red Mud Microcrystalline Glass

As countries the deepening process of industrialization,our country's solid wastes such as coal ash,red mud for measuring also increased year by year,but overall domestic for coal ash and red mud recycling way less,utilization rate is low,solid waste of a large number of accumulation caused serious pollution to the environment and caused serious influence on people's life.Solid waste is used to prepare glass-ceramics,which has a large amount of solid waste and is widely used in the market.It can effectively alleviate the accumulation problem and form a virtuous cycle.In this paper,the influence of different solid wastes on the crystallization process of glass ceramics in the preparation of glass ceramics was studied.The two most typical solid wastes,coal ash and red mud,were selected as the main raw materials to prepare glass ceramics of Ca O-Al₂O₃-Si O₂system.The thermal stability,crystallization activation energy and crystal growth index of different samples were calculated and analyzed.The results showed that the thermal stability of the base glass was significantly reduced by the introduction of red mud.When the red mud content increased from 0%to 80%,?T decreased from 357.65 to 211 and?T'decreased from 0.610 to 0.346 at the heating rate of 10oC/min.With the increase of red mud content,the crystallizing activation energy of coal ash-red mud glass first increased and then decreased.When the red mud content increased from 0%to 80%,the crystallization activation energy increased from 367.643 KJ/mol to 452.064 KJ/mol,and then decreased to 287.893 KJ/mol.When the Al₂O₃content is between 15.364%and 26.887%,the effect of blocking crystallization of glass ceramics is most obvious.When the temperature rise rate was 10oC/min,the crystallization mechanism of the microcrystalline glass samples was global crystallization.With the increase of the temperature rise rate,some samples changed from global crystallization to surface crystallization.When the red mud content is between 20%-40%and 50%-70%,the crystal phase is relatively stable.Of coal ash,red mud glass ceramics crystallization process of the study found that red mud content is 30%of the microcrystalline glass sample excellent comprehensive performance,crystallization degree is high,but its exothermic peak temperature above 960oC,crystallization activation energy is larger than 460 KJ/mol,and in order to reduce energy consumption,this paper introduced the titanium slag as nucleation agent,to further reduce the crystallization activation energy of microcrystalline glass,preparation of the coal ash-red mud glass ceramics of different content of titanium slag,and analysis the based thermal stability with different glass ceramics samples of different content of titanium slag,crystallization activation energy of glass and crystal growth index,At the same time,XRD and SEM were used to detect the microcrystalline glass samples after heat treatment.The experimental results show that the thermal stability of base glass decreases with the increase of titanium slag content.When the content of titanium slag increased to 20%,?T decreased from 320.21 to 273.15 and?T'decreased from 0.531 to 0.452 at the heating rate of 5 C/min.With the increase of titanium slag content,the crystallizing activation energy of red mud glass with fly ash decreases uniformly.When the content of titanium slag increased from 0%to 20%,the crystallization activation energy decreased from 452.064 KJ/mol to 300.990 KJ/mol.When the temperature rise rate was below 15oC/min,the crystallization mechanism of all the glass ceramics was the whole crystallization mechanism,and titanium slag promoted the crystallization process of coal ash-red mud glass ceramics obviously,so that more grains were precipitated from glass ceramics with uniform size.