The rice husk combustion in a bubbling and atmospheric fluidized bed reactor was investigated. This paper presents the rice husk ash characterization employing the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) among others. After combustion, a rice husk ash containing 93% amorphous silica and <3% unburned char was produced. Methods usually applied to fixed bed considering external sources of energy and high reaction times were employed. Thus, the potential of this type of reactors with respect to speed, continuity and self-sufficiency energy of the process was shown.

The synthesis of the ceramic pigment Victoria Green (Ca3Cr2Si3O12 ) is described. As raw materials CaCO3, Cr2O3, and SiO2 obtained from rice husk were used. Borax was used as mineralizer. Raw materials were formulated stoichiometrically and calcined from 1000 to 1200 ºC for 180 min. The main phase detected was uvarovite with particle size below 45 mm. The pigments were applied on ceramic tiles and sintered at 1150 ºC for 40 min. The synthesis process showed to be adequate to produce the green pigment, whose characteristics resemble those of a commercial pigment.