| ArticleName |
Indicators and regularities of hydrolytic decomposition
of metastable aluminate solutions in the Na2O – K2O – Al2O3 – H2O system |
| Abstract |
Target processing of aluminum ores with increased potassium content is well known in the world practice and at different stages of development of alumina production technology was associated with the use of the most available and preferable raw materials, including leucites, alunites, nepheline syenites and close to them urtite minerals. Currently, we can talk about a renaissance of interest in potassium-containing raw materials due to the gradual depletion of reserves and the impoverishment of traditional aluminum-containing raw materials against the high demand for and cost of the soda-potash products, potassium fertilizers, aluminum hydroxide, alumina, and materials based on them. This study used theoretical and experimental methods of research, including calculations of the equilibrium composition of aluminate solutions in the Na2O – K2O – Al2O3 – H2O system based on the additivity principle and experimental study of indicators and regularities of hydrolysis of aluminate solutions on aluminum hydroxide seed (decomposition), depending on the mole fraction of K2O in alkaline aluminate solution. It was found that the degree of decomposition of aluminate solutions in the Na2O – K2O – Al2O3 – H2O system has a violation in the monotonicity of its change with the appearance of a special point at the mole fraction of K2O equal to 0.33, the presence of which can be explained by a change in the process mechanism due to a change in the ionic composition of the aluminate solution. The correlation between the degree of decomposition of aluminate solutions and the value of the average median particle diameter of the resulting aluminum hydroxide precipitate was shown, indicating a close relationship between the growth processes of crystallization and the hydrolytic decomposition mechanism in general, as well as their dependence on the ionic composition of aluminate solutions. The effect of transition of supersaturated (metastable) aluminate solutions into the area of unsaturated compositions has been established, which is of theoretical significance for understanding the mechanism of decomposition of potassium-bearing aluminate solutions and of practical importance for creating an effective technological cycle for the processing of aluminum-bearing raw materials based on the Na2O – K2O – Al2O3 – H2O system.
The work was carried out with the financial support of the Russian Science Foundation under the Agreement No. 18-19-00577-П of April 28 2021 of grant for fundamental scientific research and exploratory scientific research. |
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Indicators and regularities of hydrolytic decomposition
of metastable aluminate solutions in the Na2O – K2O – Al2O3 – H2O system
