Following soda and carbon additions, the addition of lime into the sintering process of 20 g CaO to 100 g bauxite residue (80% excess to stoichiometric requirements to form Ca 2 SiO 4) is necessary to investigate the consumption of free and bound silica in desilication products, relying on higher thermodynamic affinity with calcium.
The basis of the Bayer process is an understanding of the characteristics of the sodiumhydroxide—sodiumaluminate solution relationship, namely its ability to keep sodiumaluminate in a dissolved state over a wide range of conditions, especially on the temperature and caustic soda concentrations.
Soda sintering or limesoda sintering process, began from L ouis Le Chatelier's work in 1855 in obtaining aluminum hydroxide (Al(OH) 3 ) from sintering bauxite with soda at around 1000 °C which
Overall typical composition of a bauxite residue is given in Table 2 and based on the process conditions and region, the bauxite residue composition is tabulated as Table 3 and 4, respectively. Next to the major elements like Fe, Al, Si, Ca, and Na, there are also valuable minor elements such as Ga, V, Zr, and rare earth elements (Evans, 2016).
Lime is used extensively within the Bayer process, where it performs many useful functions. In particular, it can enhance the extraction of alumina (improving the dissolution of boehmite and diaspore or the conversion of aluminogoethite), control liquor impurities (desilication, causticisation or phosphorous control), assist with the removal of impurities from the pregnant liquor (liquor ...
The alkali methods for alumina extraction from byproducts of HAC can be classified into lime sintering process, limesoda sintering process, hydrochemical process, and hematite involved roastingalkali leachingBayer process. ... Teng W, Wang XG, Qin JG, Xu P, Li PC (2010) Alkali desilicated coal fly ash as substitute of bauxite in limesoda ...
1. Milling The bauxite is washed and crushed, reducing the particle size and increasing the available surface area for the digestion stage. Lime and "spent liquor" (caustic soda returned from the precipitation stage) are added at the mills to make a pumpable slurry. 2. Desilication
The dominance of Ca in the sintering process is assigned to the excessive addition of lime. Depending upon the refining process adopted by the refinery, Al 2 O 3 ... Wu, Y.: Characterization of red mud derived from a combined Bayer process and bauxite calcination method. J. Hazard. Mater. 146(12), 255261 (2007) Google Scholar ...
In Bayer process, low temperature treatment of bauxite generally applicable to gibbsite in the presence of a significant amount of boehmite (>3%), requires a temperature increase and the addition of an additive to improve the leaching conditions. This research is based on improvement of low temperature leaching conditions 108 °C and the addition of lime during the attack of some types of ...
Sometimes [when?] lime is added at this stage to precipitate the silica as calcium silicate. The solution is clarified by filtering off the solid impurities, commonly with a rotary sand trap and with the aid of a flocculant such as starch, to remove the fine particles.
Although lime is extensively used when processing diasporic bauxites, the studies on boehmitic bauxites and the overall effects on the process are limited. In this paper, lime impact was investigated at all stages of the Bayer process including the effect on alumina quality, energy and raw material consumptions.
The production of alumina (Al2O3) from bauxite via the Bayer process is underpinned by the use of lime in a variety of process reactions. One of the most important is the causticisation of...
To simulate the hydration process of bauxite tailings as supplementary cementitious material, the hydration kinetics of a calcination activated bauxite tailingslimegypsum ternary system was investigated. Hydration heat of the ternary system was measured at 50 °C by an isothermal calorimeter. Kinetics equations were used to simulate the hydration process of the ternary system.
In the lime sinter process the additive is a calcium salt (usually calcite — ... Based on the stability field of silica gel formation, a stepwise acid leaching process for bauxite residue is proposed to facilitate downstream processing of the critical metals. Extraction of scandium from bauxite residue by highpressure leaching in sulfuric ...
The metallurgical method is a significant technology to extract valuable metals from highsilicon bauxite in industry, which can destroy the complex symbiosis and improve the reactivity by appropriate treatment methods, such as the lime Bayer process (Liu et al., 2018, du Plessis et al., 2021), the sintering process (Yu et al., 2020, Pei et al ...
During the digestion process of the Bayer method, lithium and gallium in bauxite will enter into the sodium aluminate solution (Tang et al. 2020; Xu et al. 2018 ), which will return to the digestion process for recycling after the precipitation of aluminum hydroxide from the decomposition of crystal species.
Bauxite residue is a hazardous solid waste generated during the Bayer process of extracting alumina from bauxite ore, the high alkalinity of which limits its largescale industrial applications. In order to reduce the alkalinity of bauxite residue, rich lime additions from 0 to 30 wt.% and high digestion temperatures from 250 °C to 300 °C were performed on a highferrite diasporic bauxite ...
Lime is an essential reagent required in various process steps of the Bayer process, in which bauxite ore is converted into alumina (Whittington et al. 1997), as illustrated in Fig. is used for improving conversion of goethite to hematite and dissolution of boehmite and diaspore during digestion; control of liquor impurities such as silica, oxalate, titanium and phosphorous; minimising ...
An Improved Lime Sinter Process to Produce Al2O3 from LowGrade AlContaining Resources. Yongpan Tian, Xiaolin Pan, Haiyan Yu, Yuejiao Han, Ganfeng Tu, Shiwen Bi; ... and Bauxite Alloys, Processing, and Characterization Reduction Technology Shop Technology Technology Casting
The investigational trial explored the unconfined compression strength and stressstrain characteristics of the lime treated soil composites, treated using combinations of 7% lime and %, %, 1% and 2 % bauxite residue. The lime treated soil composites were moulded in to cylindrical specimens of 38 mm diameter and height of 76 mm, cured ...
In this process, bauxite is smelted and reduced, which yields pig iron and a calcium aluminate slag. Alumina is further produced from the slag through a hydrometallurgical process. In the present study, different bauxites with different chemical compositions are smelted with lime and reduced by coke.
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