High-silicon bauxite, as a potential resource for the industrial production of alumina, contains large amounts of Al 2 O 3 and SiO 2.It mainly exists as minerals of boehmite, diaspore, kaolinite and muscovite with fine-grained dissemination and high chemical inertness, which is difficult to be separated by the beneficiation method (Pandey et al., 2010).
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A process for removing silicon dioxide from bauxite is disclosed. The method includes the step of mixing bauxite with a caustic soda liquor to form a mixture and to dissolve and stabilise at...
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In this paper, a novel process is proposed to extract Al 2 O 3 and SiO 2 from high-silica bauxite without residue discharge, that is, sintering bauxite with Na 2 CO 3 followed by two-step …
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The satisfactory results on the mass ratio of Al2O3 to SiO2 and the Al2O3 recovery were obtained for the flotation separation of artificially mixed minerals and diasporic bauxite using BHUA...
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Dealkalization is a prerequisite to converting bauxite residue into non-hazardous materials that can be used for various upcycling applications. Structural alkali (Na +) lodged inside the densely packed aluminosilicate-cages of sodalite, the dominant desilication product from refining alumina, is a common culprit in the persistence of strong alkalinity of bauxite residue.
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(mass ratio of Al 2 O 3 to SiO 2) of dis solved residues is increased to 8.55, while the A/S of the bauxite is only 4.97. Key words: Bayer process; kaolinite; pre-desilication; dissolution kinetic ...
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Zhan et al. (2013) found that Bacillus circulans, B. mucilaginosus, and B. edaphics could remove 24–52% SiO 2 from bauxite ores after 7 days of incubation. Zhao et al. (2017) screened one Paenibacillus mucilaginosus BM-4 with high desilication ability and found that the Al 2 O 3 /SiO 2 ratio of aluminosilicate minerals was improved from 3.05 ...
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The main mineral phases in high-iron bauxite were diaspore (AlOOH) and limonite (most of them are cryptocrystalline goethite (FeOOH)) together with a phase of quartz (SiO 2) and titanium dioxide (TiO 2). The mineral composition of raw ore was determined by identification of rock and minerals method according to the optical properties of the ...
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Process X: applied for red bauxite to remove iron oxide (chief impurity) Process Y: applied for white bauxite to remove Z (chief impurity). Then, Process X and impurity Z are: View Solution. Q4. Observe the following statements regarding purification of bauxite: I. During Hall's process, silica is removed as Si (vapour).
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Limestone is an impurity associated to bauxite due to geological and morphological conditions prevailing during its formation. Experimental work has shown that limestone can be easily removed from bauxite using magnetic separation techniques. Three samples of Greek bauxite were used with different CaCO 3 content, that assayed between 2.5% and 8 ...
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The major element composition of the bauxite is dominated by elevated concentrations of SiO 2, TiO 2, Al 2 O 3, and Fe 2 O 3, and analyses of element mobility within the bauxite indicate that all elements except for Nb and Ni, and to a lesser extent Cr, are depleted relative to the immobile element Ti.
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(4.1) 3 Al 2 SiO 5 (OH) 4 + 18 NaOH → 6 Na 2 SiO 3 + 6 NaAl (OH) 4 + 3 H 2 O ... Process flowsheet of bauxite ore to remove silica and reactive silica from the ore. 4.7.1.2. Magnetic separation of the bauxite ore. Magnetic separation had shown promises for some of the bauxite ores (Bhagat et al., ...
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Dissolution kinetics and removal mechanism of kaolinite in diasporic bauxite in alkali solution at atmospheric pressure Yan WU, Xiao-lin PAN, Yue-jiao HAN, Hai-yan YU ... bauxite, so all of the SiO2 are in the form of kaolinite in this bauxite. The calculated mineral composition is shown in Table 2. The A/S of the bauxite is 4.97, which
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Aluminum-silicates such as pyrophyllite, illite, kaolinite and chlorite are impurity minerals in diasporic-bauxite, it being necessary to remove these silicate minerals to improve the mass ratio of Al 2 O 3 /SiO 2 of diasporic-bauxite for the Bayer process.
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These operations – scrubbing and desliming – were necessary to remove the slimes, otherwise it would face froth control problems. After this separation, the feed sample presented 23.9% available alumina (AA), 43.7% insoluble silica (In SiO 2), and 0.9% reactive silica (Re SiO 2).
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Bauxite is the main raw material in primary aluminum production and its reactive silica content and mass ratio of Al 2 O 3 to SiO 2 (A/S) has a critical role in the economic viability of Bayer process. As a major source of the reactive silica, clay impurities should be removed from the ore as much as possible by a beneficiation method such as froth flotation before the Bayer …
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Various methods of mechanical and chemical purification of bauxite are used to preliminarily remove clay minerals (such as kaolinite) from bauxite ore . Bauxite ore of a …
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This is due to the formation of lamellar hydroxyl—sodalite (OH—SOD) which is deposited on the surface of kaolinite and hinders the further dissolution of kaolinite. Under the optimum conditions, the A/S (mass ratio of Al 2 O 3 to SiO 2) of dissolved residues is increased to 8.55, while the A/S of the bauxite is only 4.97.
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The reverse-flotation process cannot achieve effective separation of Al 2 O 3 and SiO 2 from high-ferrous bauxite [13] because high-ferrous bauxite is characterized by a high content of Al 2 O 3 ...
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For achieving this purpose, iron removal tests were performed on bauxite samples with an alumina to silica modulus of 0.73. After determining the appropriate iron removal method among the magnetic ...
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The study explores the synthesis of lightweight MgAl 2 O 4-Mg 2 SiO 4 porous aggregates using magnesite tailings and bauxite chamotte as raw materials, employing an in-situ decomposition synthesis method. The effects of raw material ratios and sintering temperature on the microstructure and properties of the porous aggregates were systematically investigated.
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A novel process is proposed to extract alumina and silica from high-silica bauxite without residue discharge. 1. Introduction. Silica is a major impurity in bauxite ores, which is commonly present as quartz (SiO 2) and phyllosilicate minerals such as kaolinite (Al 4 [Si 4 O 10](OH) 8), illite (K x Al 4 Si 8−x Al x O 20 (OH) 2) and pyrophyllite (Al 2 [Si 4 O 10](OH) 2). 1,2 When producing ...
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Silicon is the main impurity in high-silica bauxite [1], [2], [3] and causes scaling on plant surfaces while affecting the quality of alumina during alumina production, using alkaline methods such as the conventional Bayer process [4], [5], [6].With the increasing demand for alumina refineries, the utilization of low-grade high-silica bauxite has attracted substantial …
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In this section, the optimal phosphoric acid leaching conditions for the removal of SiO 2 and enrichment of La 2 O 3, Ce 2 O 3, Sc 2 O 3 and Y 2 O 3 from iron-removed BR …
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The diasporic-bauxite in China is characterized by a high content of Al 2 O 3 and SiO 2 and a low ratio of Al 2 O 3 to SiO 2 (m(Al 2 O 3)/m(SiO 2)=A/S, usually 5–6) compared with gibbsite–bauxite and boehmite–bauxite in other countries.The costs of producing aluminum oxide from such refractory bauxite by "sintering" or "combining" technologies is much higher than …
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In our previous study, TiO 2 was enriched through stepwise removal of SiO 2 and Al 2 O 3 via H 3 PO 4 and NaOH leaching from non-magnetic material, which was derived from reductive …
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The sulfur in high-sulfur bauxite not only pollutes the environment but also harms alumina production. This study investigated the removal of sulfur from high-sulfur bauxite by adding Zn or ZnO during the Bayer process. The …
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the quality of the bauxite, and more than 75% of the bauxite ore in China has an A/S ratio less than 7, while that of bauxite found in Australia and Guinea is greater than 10. There are ~150 million tons of high-sulfur bauxite reserves in China. The largest sulfur-containing com-ponent of Chinese bauxite ore is pyrite (FeS 2). The FeS 2
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