143From the moment the Bayer method appeared in alumina technology, the notion of the quality of the bauxite raw material has been a constant. The most basic and constantly accompanying impurity of the latter is silica, which almost completely dissolves dur ing the production process, transferring into sodium silicate. In turn, favorable conditions for the interac tion of sodium silicate with components of the alkalialuminate solution appear with the formation of low soluble sodium aluminum silicate hydrate (SASH) of the following chemical composition: Na 2 O ⋅ Al 2 O 3 ⋅ nSiO 2 ⋅ 2H 2 O (n = 1.75-2.00) at elevated tempera tures and the prolonged duration of some processes [1]. Several types of SASH are revealed in alumina industry: nosean, sodalite, cancrinite, zeolite, etc. They differ from each other by the incorporation of various ions in the aluminate solution into the crystal lattice skeleton and by the degree of saturation by sil ica [2]. The main negative consequence of the forma tion of these compounds is the loss of valuable compo nents of the alkali-aluminate solution with silica. Therefore, it is recommended to process the bauxites with a silicon module of ≥6-7 units using the Bayer method. The sintering method is more reasonable for bauxites with smaller silicon modules.Currently, Ural alumina plants operate using a mixture of SUBR and STBR bauxites. In the future they will process only STBR bauxites.Bauxites of the Srednetimanskoe deposit (the STBR bauxite mine) are ore of medium quality; their silicon module is mainly 6-7 units. In connection with this, it is desirable to investigate the behavior of silica in alkali-aluminate solutions.STBR bauxites belong to the boehmite-cha mosite-hematite type with a small diaspore impurity. They are high ferrous, sulfur free, and low carbonate. In contrast to North Ural bauxites (SUBR), where the main alumina containing mineral is diaspore, it is boehmite in STBR bauxites, which is confirmed by the spectral analysis data (Fig. 1). Boehmite is a more chemically active form of aluminum hydroxide when compared with the diaspore of SUBR bauxites.Silica containing minerals of the STBR bauxite are presented by chamosite and kaolinite. A higher cha mosite content is characteristic of low module baux ites. The content of these minerals considerably varies, which is a distinctive feature of bauxites of the Sred netimanskoe group. The main iron containing min eral in STBR bauxites is hematite. Abstract-A new technology of processing raw materials with the use of active alkali is suggested for bauxites of the Srednetimanskoe deposit; bauxite is opened at 300°C for 1 h. This technology makes it possible to increase the recovery of alumina to 94-98% and obtain red slimes and zeolite enriched with iron (58%) and titanium (4.8%); the environmental problem of storing red slimes is resolved. The blast furnace smelting of such slimes makes it possible to obtain naturally doped cast iron and slag enriched with titanium and rare earth metals. When purifying (desiliconizing) the a...

When bauxites from the Middle Timan and Severouralsk deposits are processed into alumina by the low-temperature sintered process the high-iron content red mud can be obtained. The red mud contain up to 58 % of iron and are a potential raw material for ferrous metallurgy. Rare earth elements (REEs) such as Sc, Y and La are converted from bauxites to red mud in the form of hydroxides during processing and are easily leached by weak acid solutions. In this work, the red mud is treated with a solution of sulfuric acid (pH = 2.5–5), the REEs pass into solution, and then the solution is neutralized to obtain a precipitate, i.e. a concentrate of rare elements. The recovery of REEs is about 75–90 % (Sc, Y, La). The high-iron content red mud is converted to the naturally-doped cast iron and titanium slag (up to 50 wt.% TiO2). As a result of processing bauxite, alumina (Al2O3), the naturally-doped cast iron, concentrate of REEs (Sc, Y, La, etc.) and titanium slag (TiO2) are obtained. The flowsheet of the proposed complete processing of the high-iron content red mud is given.

In Russia, the main feedstock for producing aluminum is bauxite. During the processing of 1 ton of bauxite into alumina (Al2O3), up to 0.5–0.6 ton of techno-genic waste is formed, that is red mud. It is not currently disposed of and accumulated in mud tailing dumps. It contains valuable components: Al – 8 %; Fe – 25 %; Ti – 2.4 % and it can be considered as a potential raw material for ferrous metallurgy and as a source of vanadium, titanium, and rare-earth elements (REE) Sc, Y, La. The paper shows the possibility of obtaining red mud with an increased iron content of up to 36 %, with an additional extraction of aluminum. Red mud from the Ural Aluminum Plant (Russia) is considered. It is proposed to direct this mud to the production of pellets for the production of cast iron. To extract aluminum from red mud, it is proposed to process the mud in a highly alkaline medium by sintering in the temperature range 300–600 °C. The resulting sinter is leached with water or a slightly alkaline solution with the conversion of aluminum compounds into solution. The red mud, obtained this way, exhibits magnetic properties. A magnetic separation was carried out, and the yield of the magnetic fraction is 79.87 %. The iron content increases by 25 % and amounts to 51.88 % of Fe2O3.

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