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When the mixture of the high-silica bauxite and Na2CO3 with mole ratio of Na2O/(Al2O3 + SiO2) of 1 was sintered at 950 °C for 30 min, diaspore and kaolinite were primarily converted into Na1 ...Web
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 of ...Web
The HPAL method was successfully applied in extraction of aluminosilicates in high-silica bauxite (Valeev et al., 2016a, 2016b), a by-product of the coagulant industry (Zhao et al., 2020b), and in the slag from the red mud carbothermic reduction smelting process (Rivera et al., 2019; Zinoveev et al., 2021a).Web
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 …Web
Aluminum production from bauxite is achieved with the Bayer process, which is a hydrometallurgical method. However, in the Bayer process, in time, it is possible to encounter problems such as the formation of excessive amounts of red mud in aluminum production, its environmental risks, its requirement of large storage sites, the excessive …Web
processing of high silica bauxites. High silica bauxites are usually considered to be those with reactive silica contents 1 in excess of ~8% by weight of the bauxite.Web
High aluminum content: Bauxite is the primary source of aluminum metal, with a typical composition of around 40-60% aluminum oxide (Al2O3). The high aluminum content makes it an important raw material for the production of alumina and aluminum. ... In the case of bauxite formation, silica and other minerals are leached out of the rock, …Web
Alumina industry is an important portion of the national economy. However, with the gradual decrease of high-grade bauxite and the increasing demand for aluminum resources, the efficient and comprehensive utilization of low-grade bauxite became more important [1, 2].Due to the low mass ratio of alumina-silica (A/S), low-grade bauxite was …Web
It can be seen in Table 1 that for the bauxite samples 1–3 from the origin of A the Al 2 O 3 content is above 51.6%, the SiO 2 content is over 8.6%, and the alumina to silica ratio is in the range of 5.5 to 6. But the bauxite from the B origin has an alumina content of about 51%, a lower SiO 2 content of less than 8.3%, and a higher Fe 2 O 3 …Web
However, Guangxi gibbsite bauxite has an alumina-to-silica ratio (A/S) of only 3.37, very different than that of high-grade Guinean bauxite, which has an A/S of up to 20. Although there have been a few studies on the high-temperature treatment of gibbsite bauxite, the effect of aluminogoethite on the digestion properties of Guinean bauxite has ...Web
High silica bauxites have been used commercially with the Lime-Soda-Sinter Process, also known also as, the Combination Process. In this process, the high silica bauxite is ground with spent sodium aluminate liquor, stored for up to 24 h in heated atmospheric pressure tanks to allow the majority of the desilication process to be …Web
This bauxite is considered to be of low grade due to its high silica content and its correspondingly low silica modulus ( μ Si = 2.5). The bauxite consists of sinters with dimensions of 1–100 μ m.Web
Deposits of bauxite ores near aluminum smelters often possess an excessively high percentage of silica. Development of such high-silica ores would be …Web
High silica bauxites are considered to be bauxites that contain > 8 wt% silica. These cannot be processed by conventional Bayer processing but require a sinter process (see Section 3.8 ). A significant proportion of global bauxite ore reserves have too high a silica content to be commercially viable for Bayer refining because high silica levels ...Web
Beneficiation of High Silica Bauxite Ores of India an Innovative Approach. Mukesh Kumar Bimalananda Senapati C. Kumar. Materials Science. 2016; Many bauxite reserves in India have Al2O3/SiO2 ratio of 4 to 6 and hence pose difficulties in production of alumina through the Bayer process.Web
1. Introduction. 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 …Web
The high silica bauxite was obtained from Shanxi Aluminum of Hejin, Shanxi province (China). The bauxite was crushed in a disc vibration grinder (RS 200; Retsch, Germany), sieved to isolate the 75- to 150-μm mineral powders, and cleaned based on the method of Sheng et al. (2008). The treated bauxite was then used for element analysis …Web
After filtering, a bauxite concentrate with a high A/S ratio is obtained, which can be applied as a raw material for the Bayer process [15–17]. Show abstract When low-grade high-silica bauxite undergoes desilication by alkaline leaching, a large amount of alkali-silicate solution will be produced.Web
The physiosorbed water on the surface of the free silica was found to have a weak adsorption band at 684 cm − 1 attributed to the Si-O-Si bending vibration mode of the water [20].Web
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 needs to be desiliconized. In this study, the effectiveness of red mud and a mixture of red mud and CaO as desilication reagents of the alkali ...Web
Considering the excellent chemical stability of silica in acids, such as HCl, HNO 3 and H 2 SO 4, the acid leaching process can realize the separation of Al 2 O 3 and SiO 2 from the high-silicon bauxite (Martinez et al., 2006, Shemi et al., 2015). However, due to its drawbacks such as strong causticity, high acid consumption and serious ...Web
Keeping the above characteristics in view, several west coast lateritic bauxite mines of India employ dry crushing−screening process to bring down silica content from the metallurgical grade bauxite [].Recently, a bauxite mine of Guinea known as AGB2A has also adopted the dry beneficiation procedure to cut down silica from about 7% to below …Web
The high-silica bauxite was mixed evenly with various amounts of Na 2 CO 3 in a ceramic mortar. The mixtures were transferred to a muffle furnace and sintered for a certain time after the temperature is raised to a specified level. The sintered samples were cooled to room temperature and then ground to below 74 μm in particle size for leaching.Web
Aluminosilicate refractories are manufactured using refractory clays, sillimanite minerals, bauxite, and mixtures of alumina and silica sand. They will refer, somewhat arbitrarily, to common crystalline compounds with melting temperatures of at least 1500 °C [2].The major categories of traditional refractories are fire clays, high alumina, and silica.Web
Mechanochemical treatment of high silica bauxite with lime in an attrition mill resulted in a 30 % drop in caustic soda consumption . Mechanical activation of bauxite in the Bayer process of alumina production was carried out during the leaching process itself [6, 9] or as a pre-treatment [7, 8]. The research on mechanical activation of bauxite ...Web
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 …Web
Thermal activation of bauxite has been proposed to enable removal of organic carbon and reducing boehmite digestion temperature. However, there is limited published research about how thermally activated bauxite behaves at pre-desilication (<100 °C) conditions. Combining x-ray diffraction and scanning electron microscopy energy dispersive …Web
The highest solution silicate concentration appeared after 30 min for activated bauxite sample with 8M NaOH, reaching a maximum concentration of 0.185 M that …Web
For instance, one tonne of silica dissolving from bauxite at the time of digestion requires 1.2 tonnes of soda. Soda is used to process high silica bauxites, and it accounts for up to 20% of alumina production expenses. High levels of reactive silica in the ore wreak havoc on the process's settling, crystallisation, filtration, and calcination.Web
