A. A. Baikov Institute of Metallurgy and Material Science RAS, Moscow, Russia:

B. G. Balmaev, Leading Researcher, Laboratory of Physical Chemistry and Aluminium Technology, e-mail: 3.boris@gmail.com

National University of Science and Technology “MISiS”, Moscow, Russia:
S. S. Kirov, Assistant Professor, Chair of Non-ferrous Metals and Gold, e-mail: kirovss@list.ru
V. I. Pak, Post-Graduate Student, Chair of Non-ferrous Metals and Gold, e-mail: pakvi@misis.ru
M. A. Ivanov, Post-Graduate Student, Chair of Non-ferrous Metals and Gold, e-mail: ivanov@misis.ru

Our paper studies the kinetic regularities of autoclave leaching of kaolin clays of East Siberian deposits with hydrochloric acid in laboratory conditions and pilot plant tests. A probabilistic-deterministic mathematical model of hydrochloric acid leaching is constructed, which allows to predict the best parameters of the process. Laboratory studies on the leaching of kaolin clays with hydrochloric acid were carried out in 50 ml ampoule autoclaves. Investigations in the pilot plant tests were carried out in a 27 l autoclave with impeller stirrer. The dependence of the reaction rate of the reaction of kaolin clay with hydrochloric acid on temperature was obtained. The values of the activation energy and reaction order for HCl are determined, showing that under laboratory conditions the process goes on in the transition region, and in the pilot plant tests – in diffusion. Dependences of extraction of Al₂O₃ in solution on the rate of mixing were obtained. An increase in the speed of rotation of the mixer from 30 to 90 rpm helps to increase the extraction of alumina into the solution from 91% to 92.82%. A constructed mathematical model of the process of leaching of kaolin clays with hydrochloric acid adequately describes the process, which is confirmed by both statistical criteria and control experiments and minimizes technological risks in the subsequent industrial introduction of the technology.
This work was carried out with the sponsorship of the Ministry of Education and Science of the Russian Federation within the fulfilment of the subsidiary agreement engagements on November 2nd 2015, No. 14.581.21.0019 (unique ID: RFMEFI58115X0019).

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