Preparation method of mullite whiskers

The invention relates to a preparation method of mullite whiskers. According to the invention, first, fly ash is placed in a corundum ball milling tank; a slurry prepared by using a planetary ball mill of the corundum ball milling tank is dried, grinded, and is sieved by using a sieve of 40 meshes; Al2(SO4)3.18H2O is grinded in a mortar, and is sieved by using a sieve of 20 meshes; fly ash, Al2(SO4)3.18H2O, and Na2SO4 are sufficiently mixed, and the mixture is placed in a corundum cup; the cup is covered and sealed; the cup is calcined in a high-temperature electric furnace, and is naturally cooled with the furnace; the material obtained after calcining is washed by using distilled water, filtered, and dried; the material is then washed by using 20% HF acid, filtered, and dried, such that the finished product can be obtained. According to the invention, fly ash, which is a solid waste discharged from a coal-fired power plant, is adopted as a main material; the aluminum content in the formula is regulated by using Al2(SO4)3.18H2O; Na2SO4 is adopted as a solvent, and the mullite whiskers are synthesized under a relatively low temperature; the lengths of the whiskers are 0.58-1.2mum, and the diameters of the whiskers are 43-69nm.