Saint Petersburg Mining University (St. Petersburg, Russia):

Brichkin V. N., Head of Chair, Doctor of Engineering Sciences, kafmetall@mail.ru
Vasilyev V. V., Assistant, Candidate of Engineering Sciences
Gumenyuk А. М., Postgraduate student

JSC Polymetal Engineering (St. Petersburg, Russia):

Nagornaya E. A., Leading Engineer, Candidate of Engineering Sciences, AlekseevaEA@polymetal.ru

The quality of bauxite is the fundamental basis for choosing the type of process for alumina production, in accordance with traditional approaches and modern challenges. The analysis of bauxite processing parameters by known alkaline methods allows establishing that not only the absolute content of the target component in the bauxite composition but also its relative content expressed by the magnitude of the silicon module is an important characteristic of bauxite quality. This allows setting the task of conditioning the bauxite composition by the value of the silicon module, which is much different from the problems traditionally solved during mineral processing. At the same time, the fundamental basis of mechanical conditioning is observance of the principle of independence of grinding of variousstrength components of mineral mass. In relation to bauxites, this principle is realized as a result of their complex polymineral composition, including quartz-feldspathic rocks, characterized by high hardness and high silica content, which creates the appropriate conditions for size classification of the components. An experimental study of a sample of low-quality bauxites showed a significant differentiation in the chemical composition of the separated granulometric fractions of the base bauxite. It is shown that additional changes in the composition of fractions occur in the process of dry and wet grinding of bauxite. It was found that the highest contrast in grinding of aluminum and silicon minerals is reached with a grinding time of 15 minutes. The subsequent optimization of the grinding mode (type of the grinding media, the filling degree of the mill, the mill speed and the dilution) showed a possibility of receiving the ground bauxite with a silicon module to 5.93 with its initial value of 4.15 with a yield of ground fraction about 94 %.
The work was performed with the financial aid from the Ministry of Education and Science of the Russian Federation (project No. 11.4098.2017/PCh, dated 01 January 2017).

1. On the strategy of scientific and technological development of the Russian Federation. Russian Federation Presidential Decree No. 642, of December 1, 2016. Moscow, Kremlin. 25 p.
2. Loginova I. V., Kyrchikov A. V., Penyugalova N. P. Technology of alumina production. Ekaterinburg: Publ. Uralskiy Federalnyy Universitet, 2015. 336 p.
3. Wang Xing Li. Alumina production theory & technology. Changsha: Central South University, 2010. 411 p.
4. Zhao Qiuyue, Zhang Zimu, Zhu Xiaofeng, Liu Yan, Lu Guozhi, Zhang Ting'an, Wang Shuchan. Economic analysis of producing alumina with low-grade bauxite (red mud) by calcification-carbonization method. Light Metals. 2014. pp. 165–168.
5. Bazhin V. Yu., Brichkin V. N., Sizyakov V. M., Cherkasova M. V. Pyrometallurgical processing of nepheline furnace charge with use of additives of a natural and technogenic origin. Metallurg. 2017. No. 2. pp. 68–74.
6. Skaarup S. B., Gordeev Yu. A., Volkov V. V., Sizyakov V. M. Dry sintering of nepheline — a new more energy efficient technology. Light Metals. 2014. pp. 111–116.
7. Wang Xing Li. Refining alumina from fly ash. Travaux ICSOBA. 2013. Vol. 38, No. 42. pp. 408–410.
8. Sizyakov V. M., Brichkin V. N., Kurtenkov R. V. Increasing all-round utilization of nepheline raw materials through belite sludge soda conversion. Obogashchenie Rud. 2016. No. 1. pp. 34–39.
9. Sizyakov V. M., Utkov V. A., Brichkin V. N., Gumenyuk A. M. Limestone-nepheline mix compsition conditioning by using alkali-free feed additives. Obogashchenie Rud. 2017. No. 1. pp. 51–55.
10. Abramov V. Ya., Nikolaev I. V., Stelmakova G. D. Physical and chemical basis of aluminum raw materials complex processing (alkaline methods). Moscow: Metallurgiya, 1985. 288 p.
11. Sabirzyanov N. A., Yatsenko S. P. Hydrochemical methods of complex bauxite processing. Ekaterinburg: UrO RAN, 2005. 340 p.
12. Yatsenko S. P., Sabirzyanov N. A., Pasechnik L. A., Pyagay I. N., Skachkov V. M. Hydrochemical reprocessing of alumina industry mud. Ekologiya i Promyshlennost Rossii. 2012. No. 11. pp. 10–13.
13. Dubovikov O. A., Andreyev E. E., Nikolayeva N. V. Microbiological conditioning of bauxites. Obogashchenie Rud. 2011. No. 5. pp. 19–23.