Improving High-Alumina Iron Ores Processing via the Investigation of the Influence of Alumina Concentration and Type on High-Temperature Characteristics

Aiming at the effective utilization of the abundant high-alumina iron ores with low iron grade, the influence of alumina concentration and type on high-temperature characteristics was clarified based on the analyses of eight typical iron ores. The results indicate that high-temperature characteristics of iron ores in various alumina types are different. Higher Al2O3 concentration is deleterious to assimilability and liquid phase fluidity, but the influence extent of each alumina type is substantially different. Kaolinite (Al2O3·2SiO2·2H2O) contributes to correspondingly better assimilability, followed by hercynite (Fe(Fe, Al)2O4), gibbsite (Al(OH)3), diaspore (AlO(OH)), and free state alumina (Al2O3) in turn. Diaspore promotes relatively higher liquid phase fluidity, followed by kaolinite, free state alumina, and hercynite, while gibbsite possesses the maximum adverse impact. Kaolinite and hercynite are more beneficial to form dendritic or acicular silico-ferrite of calcium and alumina (SFCA) with high strength due to the better reactivity, and gibbsite and diaspore lead to more formation of relatively lower strength lamellar or tabular SFCA, while free state alumina is preferable to form disseminated SCFA with rather poorer strength. Kaolinite and hercynite are the most desirable alumina types for sintering rather than free state alumina.

CFD Investigation of Bath Flow and Its Related Alumina Transmission in Aluminum Reduction Cells: Slotted Anodes and Busbar Designs

Alumina is an indispensable raw material for the modern aluminum electrolysis industry. The distribution and transmission of alumina within the bath is of great significance to maintain stable operation and reduce energy consumption. In this study, a computational fluid dynamics (CFD) model was developed to investigate the bath flow and its related alumina transmission in aluminum reduction cells. The bath flow driven by bubbles, electromagnetic force, and aluminum flow presented two different sized vortices in the horizontal plane of the anode–cathode distance (ACD). Both numerical results and industrial data show that the average alumina concentration in the half-cell at the duct end is slightly larger than that of the tap end. With the application of slotted anodes, the maximum velocity of the bath flow increased and the average velocity decreased slightly in the horizontal plane, resulting in a more uniform distribution of alumina than that in the use of unslotted anodes. The symmetrical nature of the bath flow vortices became more obvious with the upgrade of the busbar design and the alumina concentration gradient became smaller within the bath.

Deoxidizing effect on the low-alloyed steel's nonmetallic inclusion's compositions

The investigating results are given in the article for the deoxidizing effect on the non-metallic inclusion compositions tubes steels melted in the vacuum induction furnaces with periclase lining. The oxygen thermodynamic activity was calculated for the lanthanum, cerium, alumina and yttrium melts during four heats. The magnesia spinel inclusion's formation condition was evaluated depending on the deoxidizer's used and on the deoxidizing depth. It was shown how the reduced alumina concentration during the steel ladle treatment governs the non-metal inclusions' compositions and on the possibility of their modification during the commercial tubes steels melting.