Effect Of Dynamic Hydrothermal Synthesis Of Xonotlite On Filtration Separation Process

Xonotlite is a kind of semi-crystalline calcium silicate material.Because of the complex synthetic conditions,the crystallization of the material would be bad.In the filtration process,the filtration rate would be slow,the water content of filter cake would be high,and the filtration would be difficult.Therefore,this thesis,which focuses on the experiment and mechanism of the synthesis and filtration of the xonotlite,is expected to provide the theoretical basis and experimental basis for the filtration and separation issues in industry.Base on experiment,this thesis investigates the effects of different synthetic conditions on the crystalline state of xonotlite.The result shows that the synthetic temperature has great influence on the phase composition of the final product.Mechanical stirring can not only improve the dispersion of ions in solution,but also exert shear force on crystal particles.As a consequence,the particle size characteristics and crystalline state of particle would be influenced.After tracing the growth process of xonotlite,it is found out that xonotlite grows from the group of floc to fibrous crystal structure.Prolonging the synthetic time is beneficial to improve crystal structure.Aiming at the difficulties of the filtration of xonotlite and the high water content of filter cake,the experiment investigates the moisture-occurrence status of xonotlite and optimizes the filtration separation process.The result shows that the moisture content of the cake is mainly determined by the water content of surface water,clearance water and combining water.The increase of particle size can reduce the content of surface water and interstitial water in the cake,but it would produce a large amount of bound water in crystal structure.Temperature has a promoting effect on improving the filtration speed.As a kind of medium compressible material,the operation pressure of 0.2MPa is suitable for xonotlite.SDBS has the best dehydration performance,which could decrease the moisture content of the cake by 2.12% and increase the filtration rate by 1.11 times.Base on the results of the experiment,this thesis discusses the production process of xonotlite.