Preparation And Performance Research Of Glass-ceramics By The Main Raw Materials Of Coal Gangue And Rice Husk

Coal gangue and rice husks are produced as solid waste in mining and agricultural production,resulting in a series of problems such as large occupied area,serious environmental pollution and high disposal costs.At present,in the application and development of solid waste,there are problems such as low value-added products,complicated process and secondary pollution,etc.In this paper,the main purpose of using gangue and rice husk as main raw materials are to increase the added value and simplify the production process.Through a series of tests and orthogonal table analysis,the raw materials and samples were tested and characterized using methods including ray diffraction,scanning electron microscopy,differential thermal analysis,and dielectric spectroscopy.The gangue and rice husk as the main raw material to prepare the glass-ceramics were used,explored the process of melting the glass with the solid waste as the main raw material.The melting properties of matrix glasses with different compositions were studied,and the crystallization and sintering behaviors were studied.The internal structure under different heat treatment conditions was studied,and the specifications for the construction of glass-ceramics were obtained.Finally,open up the application of glass-ceramics,color and foamed glass were developed and researched.This study reaches conclusions as follows:(1)The content of Si02 and Al2O3 in coal gangue reaches about 80%,the main component of rice hull ash is SiO2,the proportion is above 90%.From the composition analysis,it can provide the silicon aluminum and reducing agent needed in the glass-ceramic melting process;Considering the graininess,the coal gangue has fine grain size and irregular shape,and the rice husk ash has a net structure with light density.After grinding,the grain size requirements of glass production can be achieved.(2)The optimum process parameters of the base glass were determined by orthogonal test as follows:8%sodium oxide melts,15%calcium oxide melts,proportion 3.2 of SiO2/Al2O3 melts at 1450 ?.Under the process parameters,the glass melt has good fluidity,low melting temperature,uniform homogenization,and easy water quenching.At the same time,the crystallization activation energy of the glass is low:Ea = 410.514kJ/mol.The utilization ratio of coal gangue in the formulation is 70%,the proportion of rice hull ash introduced is 17%,and the utilization rate of waste is high,so the cost of the formula is low.(3)The key step in the preparation of glass-ceramics lies in the rational determination of its heat treatment system.In this paper,orthogonal experiments are used to study the interrelationships between the various heat treatment process factors.The best heat treatment process through experiments is as follows:Tnucleation = 740 ?,tnucleation = 1 h,Tcrystallization = 870 ?,t crystallization ?1.5 h.Under the heat treatment process,the main crystal phase of the glass-ceramics is Anorthite,and the secondary crystal phase is Diopside,which is consistent with crystals judged based on the formula composition of the ternary system phase diagram.Observed from the microstructure,the number of crystal phases is relatively large and the distribution is uniform.The network structure is shown,and the crystal size is suitable and fully developed.(4)By discussing the influence of heat treatment on the structure and properties of the glass-ceramics,obtained:the nucleation of crystals occurs above the glass transition temperature,and the number of crystal nuclei increases with the increase of the nucleation temperature,and the shrinkage rate increases accordingly.However,as the temperature continues to increase,the shrinkage rate will decrease.At the same time,the body density will have similar trends.At a suitable crystallization temperature and time,the crystals will gradually grow and be distributed uniformly,and accordingly,the physicochemical properties of the glass-ceramics will also be improved.Thus,the temperature is too high and too low to have a bad influence on nucleation and later crystallization.(5)The glass-ceramics obtained under the proposed formulation and optimum heat treatment process regimen have a density as high as 2.55 g/cm3 and a dielectric loss as low as 0.1.The 24 hour acid-base corrosion loss weight is 1.2%and 1.4%,so the chemical stability is excellent.The glass-ceramics prepared from gangue and rice hulls as the main raw materials were prepared by adding iron oxide and cobalt oxide as colorants to produce red and green series of colored glass-ceramics with uniform coloration.By adding sodium carbonate foaming agent to prepare foamed glass-ceramics,the internal voids and bubble diameters are relatively small,the distribution is uniform,the specific surface area is large,and the connectivity of the pores is good.Both the crystallization effect and the type of crystal phase are basically the same as the ordinary glass-ceramics prepared in this paper,and their application fields are widened.