Alumina dissolution

Combining alumina dissolution, equation 16, and the anode and cathode reactions, equations 17—19, gives the overall reaction... 

Gilbert et al. [37] and Olsen [38] showed that by alumina dissolution in molten cryolite the following reactions occur as a function of increasing A1203... 

Finally, scheme D is probably more realistic than either of the previous ones. It is hard to determine without further study which effect will predominate in this case, but in any case tungstate adsorption may be expected to exert an influence on alumina dissolution rates. 

The key parameters that govern the teohnological developments are current, faradic yield, energy consumption, the kinetios of alumina dissolution and, from more recent analysis, temperature. Moreover, in a bid to avoid CO2 emissions, researchers are looking into replacing carbon anodes with dimensionally stable anodes which should produce dioxygen. However this would oause the energetio yield to decrease. 

Indeed, the oxide/water contact time is drastically reduced if one freezes the impregnated catalyst with liquid nitrogen a few seconds after impregnation, and then freeze-dries the solvent in vacuum [48]. The consequence of this procedure is to limit the extent of M0O3 formation after calcination (Figure 4.6) alumina dissolution and [AlMoe] precipitation have been inhibited, whereas conventional drying at about 100-120°C probably speeds up the alumina dissolution rate, especially since liquid water is initially present. 

The alumina addition into the electrolyte is made above the anode holes. The oxygen escape generates electrolyte circulation by the phenomenon of gas-lift, facilitating the alumina dissolution. 

Influence of LOI on Alumina Dissolution in Molten Aluminum Electrolyte... 

Experimental method and apparatus for alumina dissolution rate measurement... 

Influence of LOI on Alumina Dissolution in Molten Aluminum Electrolyte 79 Table 1.8.1 Composition of the cryolite used... 

These authors neglected both the electrostatic effect and the dissolution of alumina. Although alumina dissolution xmder the given experimental conditions was checked and its contribution to the total consumption seemed to be not significant, the experimental... 

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