Study On Preparation Of Fly Ash Based Inorganic Fibers And The Melting Characteristics Of Its Raw Materials

Shanxi province is an important coal chemical and coal power industry base in China.In a long time,it is also an important energy export and a heavy industry province,which has made outstanding contributions to the national economic construction.At the same time,it has also produced and stockpiled a large number of coal-based solid wastes,such as fly ash,coal gangue,desulphurization gypsum,magnesium slag,and steel slag.As a result,a series of problems,such as,environment pollution,ecological security,has produced due to the inability of consuming them in time.To change this situation,the utilization of solid waste resources need to be solved urgently.The utilization of coal-based solid wastes in building materials is the main way to realize resource recycling at present and in the future.However,the low overall utilization rate is still an important factor restricting the efficient utilization of solid waste.Using solid waste resources to explore new products with high value and realize a wide application is an important way to ease the current contradiction between production and consumption.In this study,based on the previous research about fly ash mineral wool fibers,a fly ash-based continuous fiber produced from fly ash,magnesium slag,and less additive was prepared in the lab.It was considered as a novel method of fly ash recycling,meanwhile,extend a new field of inorganic continuous fiber made from industry solid wastes resources in China.In this study,fly ash and magnesium slag,as the main raw materials,were selected to prepare fibers at different formulations.The melting behavior of these raw blends,including the melting characteristics and crystal structure changes during the process of temperature rise were studied through ash melting point tester,X-ray diffractometer,infrared absorption spectrum,and other equipment.The change properties of temperature-viscosity during the process of temperature-cooling are measured by high-temperature rotational viscosity tester.Some continuous fibers are prepared.The main results are as follows:(1)Eight blends with different acidity coefficients were prepared using fly ash and magnesium slag as the main raw materials.The acidity coefficients are as follows: M_K1.0,M_K1.2,M_K1.4,M_K1.6,M_K1.8,M_K2.0,M_K2.2,and M_K2.4.The change curves between the melting temperature of these blends and acidity coefficients were tested and recorded.The results show that the melting temperature of blends gradually first decreases with the increase in the acidity coefficient from M_K1.0 to1.8,then increases when the acidity coefficient further enhance from M_K 1.8 to 2.4.(2)To explore the melting behavior and the transformation of the crystal inside these blends,these blends were calcined at a gradient-increase temperature in the region near the melting point of every blend,obtained samples were tested.The results indicated that the main crystal phases of the samples with a low acidity coefficient from M_K1.0 ~ 1.6 were Akermanite and Gehlenite.With the increase of acidity coefficient from M_K1.8 ~ 2.4,Labradorite and Bytownite appear in the samples,meanwhile,Labradorite,and Anorthite become the main crystalline phases.That is considered as the main reason that resulted in the melting temperature of the above blends first drop then increase with the acidity coefficient increasing during the range from M_K1.0 to 2.4.(3)The results show that the viscosity of the samples increases with the decrease of the melt temperature,but the viscosity and the viscosity growth rate of the samples with different components are different.Through investigating the influence of differently chemical constituents on the viscosity of these melts,results indicated as follows: Si O2 attributes to increase the viscosity;a small increase of Al2O3 reduce the viscosity,while an increase in the content of Al2O3 can cause the viscosity and the rate of viscosity growth increase;Ca O and Mg O reduce the viscosity,but if too much Cao and Mg O in the sample cause the viscosity to increase rapidly at an uncertain temperature point.(4)The viscosity of the mixture of fly ash and magnesium slag is predicted by using the prediction model of the fusion viscosity of coal ash.By the improved S2 model,the viscosity of M_K1.4 ~ 2.4 blends below 25Pa*s can be predicted.(5)The blend of M_K1.6 was used to produce continuous fiber.Compared to basalt fiber produced in the same lab in mechanical properties and heat resistance.The tensile strength of basalt fiber can reach 1500 MPa,the tensile modulus can reach above 15 GPa,and the solid waste fiber can reach 900 MPa and 11 GPa respectively.The basalt fiber produced can withstand 500?.When the calcination temperature reaches 600?,the basalt fiber begins to break seriously.However,the fly ash fiber can still maintain a complete fiber shape and retain certain mechanical properties after calcining even at 600?.The experimental results show that it is feasible to prepare continuous fibers from solid wastes such as fly ash.Although the mechanical properties of the fiber are slightly insufficient,it shows good heat resistance,coupled with the low cost of solid waste,the prospect,and the advantages of fly ash fiber are obvious.It is necessary to go further based on the basis of the existing research results.