The process of carbonization of aluminate solutions is one of the main in the hardware and technological schemes of alumina production from nepheline and low-grade bauxite. Total energy costs for this process are determined by the power consumed by agitating devices and spent on gas supply to the apparatus. The value of the latter depends on the hydraulic resistance of carbonizers and gas flow rate. Varying geometrical parameters of the mixing device and liquid level in the apparatus, we were able to select the best operating modes of carbonizer, as well as to study the effect of gas speed and speed of the mixing device on the mass transfer coefficient.
Currently, aluminum smelters require alumina of higher quality in terms of physical properties, so many studies are aimed at obtaining sand alumina. The method of obtaining sand alumina proposed by the St. Petersburg Mining Institute is considered. The influence of seed coarseness on the formation of productive alumina is considered. The influence of seed coarseness in the Bayer method and in the method of sintering with carbonization of aluminum hydroxide is studied. The proposed method of alumina production is at the stage of scientific research, so the introduction into the technology is not yet discussed.
Currently, aluminum smelters are in demand for alumina of a higher physical quality. Therefore, many studies are aimed at obtaining sand alumina. The method of obtaining sand alumina proposed by the St. Petersburg Mining Institute and the process of alumina structure formation are considered. Much attention is paid to the induction period of the carbonization process, since the formation of the structure of coarse-grained hydroxide occurs precisely in this period. An analysis of the relationship between the induction period during carbonization and the structure of the future main phase released from the aluminate solution during mass crystallization, the mechanism of the induction period in the carbonization process is given. The proposed method of alumina production is at the stage of scientific research and is not yet ready for implementation.
