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For this reason, they are also referred to as gibbsitic alumina and kaolinitic silica. High-grade bauxites contain N41 wt% AvAl 2 O 3 and b5 wt% RxSiO 2, while low-grade bauxites contain b 41 wt ...
For the utilization of low-grade bauxite in alumina refineries, numerous studies have focused on the high silica removal ratio in bauxite or roasted bauxite. The desilication concentrate exhibits high A/S. 7, 8, – 9 In the desilication process, silica minerals in the bauxite dissolve in the caustic solution, thereby forming a large amount ...
Deposits of bauxite ores near aluminum smelters often possess an excessively high percentage of silica. Development of such high-silica ores would be beneficial to alumina producers. Therefore, unique industrial and operational experience in the field of high-silica bauxite processing was gained at the Russian National Aluminium-Magnesium Institute, St. …
Bauxite is widely used to produce alumina. There are many bauxite resources with high iron content. These resources could not be processed and utilized efficiently due to the high concentration of iron (Fe). The alkaline leaching process has been proposed to remove iron from these bauxite resources. Therefore, in this study, the alkaline leaching process was …
In this study, low-grade bauxite ore from Seydişehir (Konya, Turkey) containing 57.33% Al2O3 and 9.01% SiO2, (A/S = 6.36) was investigated to determine the modal mineralogy and mineral liberation ...
Bauxite is the major alumina (Al 2 O 3) bearing ore used in the aluminum manufacturing industries.The bauxite containing less than 50% Al 2 O 3 is called low-grade bauxite ore which is commonly used for the alumina -based abrasives and refractories productions. The alumina -silica and alumina -ferrite complexes are the foremost impurities …
Acid selection for REEs leaching from bauxite residue. To choose the best leaching agent and optimum operating conditions, a systematic investigation was performed using HNO 3, HCl, and H 2 SO 4 ...
Keywords: Bauxite beneficiation, Clay removal, Silica reduction, Hydrocyclones. 1. Introduction. Bauxite is the main ore for production of metallic aluminum. Production is generally carried …
Bauxite reaction residue (BRR) produced from the poly-aluminum chloride (PAC) coagulant industry is a solid acidic waste that is harmful to environment. A low temperature synthesis route to convert the waste into water glass was reported. Silica dissolution process was systematically studied, including the thermodynamic analysis and the influence of calcium and aluminum on …
with high silica bauxites. Currently a number of bauxite producers, in Brazil, Indonesia and Australia for example, wash lateritic ores to remove kaolinite via processes utilizing screens and or hydrocyclones. These facilities comprise approximately 25 % of the global bauxite tonnage, or more than 60 MTPY [2].
Two highly effective Si-solubilizing bacterial strains H19 and G21 were obtained. • H19 and G21 could significantly (p < 0.05) remove Si from the high Si bauxite.The ratio of Al 2 O 3 /SiO 2 of the bauxite treated with H19 and G21 was more than nine.. H19 and G21 produced organic acids and EPS during the bio-desilication process.
Strains H19 and G21 could significantly remove Si from the high silica bauxite by the production of organic acids and expolyssaccharides. Furthermore, our findings indicated that Burkholderia anthina G21 had a greater bio-desilication from the bauxite than Arthrobacter pascens H19 by producing more H + and higher organic acids during the bio ...
The conventional process of bauxite ore dressing consists on the removal of natural mud through the steps of crushing, semi-autogenous grinding, crumble in trommel, followed by the
Fig. 1 Flowsheet of iron removal process from Severoonezhsk bauxite The efficiency of iron leaching (α) was calculated by α=[VCFe/(mwFe)]× (1) where CFe is the iron concentration in the filtrate detected by inductively coupled plasma optical emission spectrometry (ICP-OES), g/L; V is the volume of the iron chloride solution, L; m ...
IMPROVED METHODS FOR REMOVAL OF SILICATE DEPOSITS T.R. McCartney1, Samar Gharaibeh1, Roxanne Shank1 1 # 2-321 37 N.E. Calgary, AB, T2E6P6 mccartney.thomas@cleanharbors: None ABSTRACT The removal of silica scale deposits from process equipment represents a substantial challenge in chemical cleaning.
Typically, the production of 1 t bauxite concentrate with A/S (mass ratio of alumina to silica) of 8−10 will generate about 0.3 t bauxite tailing with A/S of 1.5−2.0 by treating raw bauxite ...
More than 99% of the iron could be extracted under optimized conditions [109,110]. Valeev et al. [111] found that pre-calcination of Severoonezhsk bauxite at 700 • C for 0.5 h resulted in a ...
For the utilization of low-grade bauxite in alumina refineries, numerous studies have focused on the high silica removal ratio in bauxite or roasted bauxite. The desilication …
The high-silica bauxite sample used in this study had been described in our previous study, which has a high Al 2 O 3 content of 62.92%, a high SiO 2 content of 16.72%, …
A process for removing silica from bauxite is disclosed. The method includes the step of mixing bauxite with a caustic liquor to form a mixture and to dissolve and stabilise at least a substantial part of the reactive silica from the bauxite. The caustic liquor is selected to have a high caustic concentration and a high alumina content.
When low-grade high-silica bauxite undergoes desilication by alkaline leaching, a large amount of alkali-silicate solution will be produced. To realize its recycling, the alkali-silicate solution ...
and the various removal mechanisms and strategies that exist to manage them are reviewed, and some of the issues and challenges that have arisen as a result are discussed. The influence that impurities have upon the characteristics of bauxite residue is also described. Keywords: Organics, oxalate, sulfate, causticisation, bauxite residue 1.
One of the issues encountered during the Bayer process is the presence of silica in bauxite samples, particularly in the form of Kln (Al 2 O 3.2SiO 2.2H 2 O) or reactive silica. ... Certain acids can reduce silica solubilization and remove other elements such as iron (Zhu et al., 2020). The high concentration of acid during leaching generates ...
The Bayer process is a chemical process for refining aluminium hydroxide, Al(OH) 3 from bauxite; this aluminium hydroxide is subsequently calcined to produce alumina, Al 2 O 3.The …
Abstract When producing alumina from aluminum-containing raw materials (bauxite, alunite), it is important to control the silica level in a solution of sodium aluminate. The studies show that this adsorbent having layered binary hydroxides, such as hydrocalumite sulfate AFm-SO4, is characterized by excellent desilication properties. The temperature, time, and …
Leaching Kinetics Both bauxite and activated bauxite begin to dissolve upon contact with the alkaline solution (4 M and 8 M NaOH), the main elemental (Si, Al, Ti and Fe) concentrations in the liquor are shown in Fig. 1.The solution silicate dissolution -precipitation pattern is seen Fig. 1a, which is similar to that of pure kaolinite or metakaolin.
DOI: 10.1016/J.MINENG.2008.09.001 Corpus ID: 97467177; Separation of silica from bauxite via froth flotation @article{Massola2009SeparationOS, title={Separation of silica from bauxite via froth flotation}, author={Camila Peres Massola and Arthur Pinto Chaves and J.R.F. de Lima and Christian Fonseca de Andrade}, journal={Minerals Engineering}, year={2009}, …
The more is the silica, higher is the soda consumption which increases the cost of alumina production. Physical beneficiation techniques are employed to reduce the reactive silica content of bauxite. Based on several investigations it has been made possible to remove ~30% of silica with 92% recovery depending on the characteristics of the ore.
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. A new quaternary ammonium salt (DTAL) has been shown to be efficient in the flotation of these silicates.
A new process of Al 2 O 3 production from low-grade diasporic bauxite based on the reactive silica dissolution and stabilization in concentrated NaOH-NaAl(OH) 4 solutions is proposed and proved feasible. NaOH and Al 2 O 3 concentrations and leaching temperature were found to be the main factors affecting the leaching process of reactive silica. The A/S (mass …
