Study Of Desilication Process Of Micro-Crystal Muscovite From West Sichuan

Micro-crystal muscovite from west Sichuan area is an important resources of Aluminosilicate minerals and it is also an important raw material with preparation calcined mullite. But compared to chemical composition of mullite, the content of SiO₂ in micro-crystal muscovite relatively high, the content of Al₂O₃ is relatively low. It can not get mullite with high purity that preparation with calcined micro-crystal muscovite. Paper use micro-crystal muscovite from west Sichuan area as material, the experiment use high temperature of calcination company with alkali leaching, desilication of it that's designed to reduce the content of SiO₂ in micro-crystal and increase the rate of Al/Si. To improve the purity of mullite that preparation of micro-crystal muscovite which has important academic significance and practical value.The paper through high temperature of calcination make the SiO₂ in micro-crystal muscovite become"active". The aqueous alkali will make the"active"SiO₂ become soluble silicate. It achieve that reduce the content of SiO₂, through the technology of desilication. Paper discussed the effect of desilication of micro-crystal muscovite at different conditions that including: calcination temperature,alkali concentration,leaching temperature and time etc. By XRD,SEM etc characterized on the experiment that preparation of mullite use desilication of micro-crystal. The main work and results of this paper are as follows:(1) The result of process conditon optimization shows that the better conditions of desilication of micro-crystal muscovite are: calcination temperature is 1250℃, holding 60min, for the first time of the desilication content of 20% NaOH (liquid to solid ratio 25:1); the second time of the desilication content of 15% NaOH (liquid to solid ratio 35:1), the leaching temperature is 90℃, leaching time 120min.(2) Under the better of process condition optimization, the content of SiO₂ in desilication micro-crystal muscovite reduced from 56.66% to 27.36%, and the content of Al₂O₃ increased from 24.26% to 45.32%, molar ratio of Al₂O₃/ SiO₂ increased from 0.25 to 1, the desilication has obvious effect.(3) The characterization of XRD,SEM result shows that preparation mullite with desilication micro-crystal muscovite is better than undesilcation.(4) Use of micro-crystal muscovite after desiliation as raw material, When the temperature reaches 1400℃, mullite began to form, with the calcination temperature, mullite content increased and the glass content reduced. The better calcination temperature is 1450℃, holding 3 hour; prepared of mullite crystal is well-developed, show columnar, generally the colun length is 0.5～2μm.