Ferric bauxite, a type of bauxite with high hematite content, has yet to be commercialized. Direct reduction [1−2] can realize ferric bauxite comprehensive utilization; however, the sodium carbonate consumption in direct reduction is considerably higher than that in the ordinary bauxite processing technology [3]. Previous research
Perovskite 1. Introduction Lime is often considered as a panacea in the Bayer process. Its uses are so widespread that there is virtually no unit operation where it does not find an application. Table 1 gives an overview of the main uses of lime in the Bayer process, including low temperature applications (not all applications are given).
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 Bayer process is the principal method for the production of alumina from bauxite worldwide. The modern version of the process (developed in the 1880's) still maintains the key steps of dissolution of aluminarich minerals into hot caustic solution, separation of the insoluble phases, followed by gibbsite precipitation and calcination of the gibbsite to alumina (Al 2 O 3).
Most authors' studies have focused on the pyrometallurgical process, especially in the smeltingreduction process for treating lowgrade bauxite. Sellaeg et al. [74] processed the gibbsitic bauxite mixed with lime and coke via the Pedersen process at 1600 ℃ for 60 min. The separation of pig iron and calciumaluminate slag could be achieved ...
Bauxite residue is the industrial solid waste discharged from the production of alumina by bauxite, which contains a certain amount of ferric oxide in a reddishbrown color, so it is also called "red mud", and is a typical nonferrous metallurgical solid waste (Wang et al. 2018; Xue et al. 2022).The varieties of bauxite residue depend on the grade of the bauxite and alumina production process.
The mechanochemical processing of bauxite with lime has been investigated. The milling of bauxite and lime mixtures in an attritor mill resulted in the formation of an iron rich hydrogarnet phase in bauxite/lime slurries containing greater than 9% CaO. ... The role of lime in the Bayer process with less lime is to eliminate the harmful effect ...
Different ways for alkaline recovery of aluminum from bauxite residue are considered from the literature and examined in experiments. The advantages and disadvantages of a hightemperature digestion via Bayer process and sodalime sintering process are elaborated and compared. As a hybrid process, bauxite residue undergoes a reductive smelting process with lime addition in an electric arc ...
Bauxite residue is a highly salinesodic tailings material formed as a byproduct of the Bayer process for alumina production. In situ remediation of bauxite residue has the potential to provide an effective means for accelerated rehabilitation of residue storage areas. However, previous work has predominantly only used chemical and physical amendments to date, limiting rates of pH ...
The Bayer process simulation is based on the modelling of selected and defined unit processes and inputoutput parameters from the published literatures, described in the following section. In the Bayer process simulation, the bauxite ore, extraction liquor and lime addition are mixed and heated in digesters in the pressure leaching step.
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
Bauxite is generally extracted by open cast mining, being almost always found near the surface, with processes that vary slightly depending on the location. Before mining can commence the land needs to be cleared of timber and vegetation. Alongside this process may be the collection of seeds and/or saplings, for inclusion in a seedbank, which ...
The effect of lime on gibbsite bauxite digestion is different from its effect on diaspore bauxite due to its different composition and digestion properties [15, 16]. In one report, gibbsite bauxite was digested by adding 1% lime at 145 °C, achieving a better digestion efficiency of %. However, excessive lime addition will lead to excess ...
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).
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 ...
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.
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 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 ...
The flotationBayer process has been widely applied in the alumina refineries, but it introduces large amounts of hazardous organic reagents and produces tailings totaling of about 25% of the initial bauxite ores in weight. 25,26 The lime Bayer process has been also employed to process a portion of highsilica bauxite, but it cannot ...
Based on lime sintering method, a novel process of alumina production from lowgrade bauxite containing sulfur or fly ash is carried out in this paper. The phase of alumina transforms from 12CaO·7Al 2 O 3 (C 12 A 7) to 4CaO·3Al 2 O 3 ·SO 3 (C 4 A 3 S), whose alumina leaching property is better, through decreasing sinter temperature and time ...
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 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 basis of the ...
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