Institute of Metallurgy of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia:
G. N. Kozhevnikov, Head of Laboratory of Electrothermy of Reduction Processes
A. G. Vodopyanov, Leading Researcher
V. A. Pankov, Leading Researcher, e-mail: pankov_va@mail.ru
B. P. Kuzmin, Senior Researcher

This article gives the results of research of joint processing of Middle Timan bauxites (Komi Republic) and red mud disposal areas of Urals Aluminum Smelter (Kamensk-Uralsky, Sverdlovsk Oblast) for the purpose of development of process flowsheet. Technology includes the following reduction melting:
— melting of the charge, containing 36.5% of bauxite, 36.5% of red mud, 19.2% of lime and 7.8% of petroleum coke with obtaining of cast iron (0.65% of Si);
— melting of the slag, based on calcium aluminates (12CaO·7Al₂О₃ and CaO·Al₂O₃), containing 0.228% of rare-earth metals (Sc, Y, La, Ce, Pr, Nd).
Obtained slag is leached in Na₂CO₃ – NaOH solution at the temperature of 353 K during 40 minutes. Grade of Al₂O₃ leaching in the solution was 91.83%. The slime, based on calcium carbonate and metal hydroxides, and containing 0.302% of rare-earth metals, was processed by the solution with 30% of HNO₃. Hydroxides of iron, aluminum and rare-earth metals were consequtively precipitated from obtained nitric acid solution in the range of pH = 3.2 to pH = 8.0. The precipitate, containing 81% of iron oxide and 2.5% of alumina, was released from the solution with pH=3.2. Precipitation of hydroxides of yttrium, cerium and neodymium was started with pH > 3.2, pH > 4.4 and pH > 5.5, respectively. As a result, there was obtained the precipitate of hydroxides, containing 89.4% of Al₂O₃ and 0.95% of rare-earth metals. Concentration of precipitate on rare-earth metals was carried out by its processing in NaOH solution. As a result, there was obtained the concentrate with 9.18% of rareearth metals. Processing is carried out without formation of wastes and worsening of environmental status. Obtained results will be tested and specified during the industrial testings. The practical significance of the work is concluded in expanding of Russian resource base for the production of alumina, titanium and rare elements.

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