The solubility of alumina in molten Na 3 AlF 6 containing various amounts of AlF 3 , CaF 2 , and LiF was determined by measuring the weight loss of a rotating sintered corundum disc. The results were fitted to the following empirical expression:.50[LiF] 3 3 42[LiF] ⅐ [AlF ] 3 Ϫ 0.20[CaF ] Ϫ 0.30[MgF ] ϩ 2 2 2000 ϩ [LiF] ⅐ [AlF ] 3 1.5 2.2[LiF] B ϭ 4.8 Ϫ 0.048[AlF ] ϩ 3 3 10 ϩ [LiF] ϩ 0.001[AlF ] 3where the square brackets denote weight percent of components in the system Na 3 AlF 6 -Al 2 O 3 (sat)-AlF 3 -CaF 2 -MgF 2 -LiF and t is the temperature in degree Celsius. The standard deviation between the equation and the experimental points in the temperature range from 1050 ЊC to about 850 ЊC was found to be 0.29 wt pct Al 2 O 3 . A series of revised phase diagram data of interest for aluminum electrolysis was derived based on the present work and recently published data for primary crystallization of Na 3 AlF 6 in the same systems.

Modifications of CaO-based sorbents with various inorganic salts to overcome the degradation in the reactivity between the active material and CO2 in a carbon capture process have previously been evaluated. The present paper focuses on the performance of a novel CO2 capture technology, where CaCl2 is applied as the solvent for the dissolution/dispersion of CaO and CaCO3. CO2 capture by CaO was carried out with carbonation temperatures in the range of 770–830 °C by bubbling simulated flue gas through the melt, using a fully automated flow-through atmospheric pressure reactor. Subsequently, decomposition of the formed CaCO3 to CaO and CO2 was conducted at 910–950 °C using pure N2. Online gas analysis was performed using a Fourier transform infrared (FTIR) gas detector and gravimetric analysis. The results indicate that the CaO carbonation efficiency decreases at temperatures higher than 800 °C. Increasing the concentration of CaO enhances the carbonation reaction. The amount of CO2 uptake for 15 wt % CaO in calcium dichloride was 0.541 g of CO2/g of sorbent. Moreover, investigation of CO2 absorption/desorption by 5.32 wt % CaO in CaCl2 at 787 °C showed an increase in CaO reactivity, defined as the ratio between the real and theoretical CO2 sorption per unit of CaO, from 55.4 to 64.2% after 10 cycles. In all cases, the decarbonation process proceeded rapidly, reaching 100% efficiency.

No abstract

Gas induced bath circulation in the interpolar gap of aluminium cells was studied in a room temperature physical model and by computer simulation. The circulation velocity increased with increasing gas formation rate, increasing angle of inclination and decreasing bath viscosity, while it was less affected by anode immersion depth, interpolar distance (in the normal range), and convection in the metal. A typical bath velocity near the cathode was 0.05 m s-1. The flow velocity decreased with decreasing bubble size. The results were fitted to a simple semi-empirical expression, and the velocities measured in the model experiments were in good agreement with the findings of the computer simulation.

Thermocells represent a promising way to utilize heat as a power source. The aim of this work is to develop a thermocell with identical gas electrodes using molten carbonate-based electrolytes. The cell can generate power from waste heat, and can also utilize the CO 2 rich off-gas available in metal producing industries. The flow rate of the gas supply to the electrodes needs to be optimized. Its effect on the Seebeck coefficient was not studied systematically before. The addition of solid oxide to the molten carbonate melt alters also the system's Seebeck coefficient. We report measurements where we vary the content of solid oxide in the liquid eutectic electrolyte mixture as well as the electrode gas flow rate. The Seebeck coefficient is reported for various ratios of eutectic (Li,Na) 2 CO 3 molten carbonate and dispersed solid oxide MgO, and for varying gas (CO 2 |O 2 ) flow rates to the electrode interfaces.