Bauxite is mined and transported by conveyor to a processing plant, screened and washed, then placed into blended stockpiles to feed the alumina refinery. While being stacked to the stockpile, the ore is sampled. Completed stockpiles must be acceptably close to target grade (composition), not only in alumina, but also in residual silica, carbon and sodium carbonate. The mine is an open-cut pit....

Recent studies have shown that the mullitization of diphasic aluminosilicate matrices comprising transitional alumina and amorphous silica occurs via a nucleation and growth process. Nucleation is preceded by a temperature-dependent incubation period. Following this incubation period, rapid nucleation of mullite occurs, producing about 1.8 X 10" nuclei/cm3, which remains constant throughout the...

Surfactant-templated silica thin films are potentially important materials for applications such as chemical sensing. However, a serious limitation for their use in aqueous environments is their poor hydrolytic stability. One convenient method of increasing the resistance of mesoporous silica to water degradation is addition of alumina, either doped into the pore walls during material synthesis...

Colloidal silica bonded refractory castables have been developed recently. It was found that colloidal silica is one of the best binders can substitute other binders such as cement in No Cement Castable (NCC) and Ultra Low Cement Castable (ULCC) refractories. Also composition of colloidal silica with appropriate additives resulted in a gel form which makes the initial strength. Moreover, the na...

Catalytic total oxidation of noxious volatile organic compounds (VOCs) is an important process to remove these from the atmosphere. This first systematic study influence support on activity iridium oxide supported catalysts for VOCs. Iridium titania, ?-alumina, silica and zeolites have been prepared using different calcination temperatures. The short chain alkanes their mixtures has evaluated p...

The highly ordered mesoporous silica media, SBA-15, was synthesized and incorporated with iron, aluminum, and zinc oxides using an incipientwetness impregnation technique. Adsorption capacities and kinetics of metal-impregnated SBA-15 were compared with activated alumina which is widely used for arsenic removal. Media impregnated with 10% of aluminum by weight (designated to Al10SBA-15) had 1.9...

Rapid thermal treatments potentially allow for a significant reduction in production time of ceramic multilayered membranes, in turn aiding increased industrial application of these membranes and accelerating research on their development. Two methods are proposed for the rapid thermal treatment of thin supported inorganic membrane films. Both methods involve an instant increment in temperature...

The objective of this study was to investigate the effect of hydrofluoric acid etching treatment on the surface characteristics of zirconia and Streptococcus sanguinis (S. sanguinis) and Porphyromonas gingivalis (P. gingivalis) biofilm formation on zirconia. Zirconia specimens were prepared with different treatments, including being polished with 1000-grit SiC abrasive paper as the control grou...