Sinterization of Doping Mullite with Rare Earths Using a Silica Rich Residue from a Geothermal Power Plant

Abstract

Using the conventional sinterization process, we have obtained a mullitic material using as source of silica a residue originated inthe Cerro Prieto Geothermal Power Plant (Baja California, Mexico). This residue has been purified and used in the preparation of vitreous, refractory and Si 3 N 4 materials[1,2]. We are interesed in expanding the applications and uses of this silica rich residue. In this work we study the formulation which corresponds to the stoichiometric ratio (3Al 2 O 3 .2 SiO 2 ) changing this with the adition of about 2% w/w of rare earths as doping agents. In every case we obtained mullitic materials fully identified by X - Ray Diffraction and microanalysed by Scanning Electron Microscopy (SEM). The mechanical properties assayed by the method of indentation were satisfactory, and comparable with those obtained from other synterezed materials prepared with other sources of silic materials. Our results indicate that this silica rich residue (obtained from the operation of geothermal power plant) can be used in the preparation of ceramic materials,especially in those in wich the mullite is used as the starting raw material of composite materials. We have observed the presence of a considerable quantily of micropores in these composite materials which can be attributed to the nature of the silica residue used: microamorphous with a median particle diameter between 0.21 to 11.36 micron.