Of all Bayer process impurities, few attract more attention than the simplest dicarboxylate. While some oxalate enters the Bayer process with bauxite as oxalic acid adsorbed on various minerals, the majority is created by the oxidation and pyrolysis of bauxite organics under Bayer digestion conditions. The rate of its formation in digestion is ...
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Abstract Bauxite residue (red mud—RM), a byproduct of the Bayer process for refining bauxite to alumina, is highly alkaline (pH ∼ 13) and its treatment and storage poses unique waste management challenges. In this work, the acid neutralizing capacity (ANC) of Jamaican RM from a storage facility in Sherwin, Texas, was measured, and the solid and aqueous phase contributions to the ANC were ...
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Bauxite residue is a strongly alkaline solid waste which is generated by the alumina refining sector. This waste stream may represent a high risk to the surrounding environment during the storage process (Jiang et al. 2022; Wu et al. 2020).Consequently, there have been several investigations of methods relating to for the safe disposal of bauxite residue.
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The obtained results indicate that the above process technique is an unique method for the preparation of nano alumina (Al2O 3) from natural source such as bauxite. View Show abstract
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The gibbsite bauxite from Shandong was also processed with CalcificationCarbonization method. The gibbsite bauxite is easier to dispose than diasporic bauxite, so a lower calcification temperature is chosen at 180 °C. The concentration of Na 2 O and Al 2 O 3 is and g·L −1. The calciumsilicate ratio n(CaO)/n(SiO 2) = 3: The ...
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The solid addition of a calcium source, such as gypsum or bassanite avoids many of the complications mentioned thus far for 'inprocess' bauxite residue neutralisation, however it appears that the effectiveness of these compounds is compromised by encapsulation, requiring relatively higher dosages to be used.
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The added amount of calcium oxide has a large influence on the calcification dissolution process of bauxite, the mass fraction of Na 2 O in the calcified slag can be reduced to % when the ratio of calcium to silicon reaches :1, and the slag is a single hydrated garnet phase.
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The process of extracting aluminum from bauxite involves crushing and refining the mineral to produce alumina, which is then used to produce aluminum metal. ... When bauxite is processed with limestone and heated in a kiln, it produces a type of cement known as calcium aluminate cement. Chemicals: Bauxite can be used to produce a variety of ...
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Bauxite residue, or red mud (RM), is an alkaline sludge waste produced via the alumina extraction process in bauxite mines. Depending on the source of bauxite, this residue can be considered as a ...
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In addition, slaked lime (Ca(OH) 2) is typically added within the Bayer process to enhance extraction of the available alumina from bauxite and this can lead to the formation of many solid phase calcium hydroxides, carbonates and aluminates, such as TCA (tricalcium aluminate — Ca 3 Al 2 (OH) 12). These solids act as an alkalinity store and ...
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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. The undissolved waste after the aluminium compounds are extracted, bauxite tailings, contains iron oxides, silica, calcia, titania and some unreacted alumina.
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Abstract The recovery of major components of bauxite residue by carbothermic reduction at °C and subsequent slag leaching in a Na3CO3(aq) solution is studied. Iron recovers primarily to pigiron and lime is added to tune the calcium aluminate slags towards the highly leachable mayenite phase. The concentration of aluminum in the leachate correlates well with the occurrence of ...
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He achieved this by using bauxite and lime as raw materials, and burning them together in a cupola furnace. Published by Rankin and Wright in 1915, the limealumina phase diagram demonstrates the presence of five calcium aluminate compounds—CA, CA 2, C 3 A, CA 6, and C1 2 A 7 .
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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 to a large amount of red mud discharge, most of the lithium and gallium in the ...
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Sintered calcium aluminate is produced by sintering of high purity alumina and low silica limestone. Fused calcium aluminate is produced by melting of high grade bauxite and low silica limestone and then solidifying and crushing the molten material. In both the process of manufacturing selection of raw materials is an important aspect.
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AntiSkid/AntiSlip Protection. Calcined Bauxite is an ideal aggregate for antiskid applications. It is used extensively for vehicle skid prevention and on surfaces requiring additional safety. The bauxite may be trowelled into fresh concrete, added to paints or applied to surfaces using resin cements and adhesives.
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Calcium oxide plays an important role in alumina production by binding SiO2 from aluminosilicate raw materials (bauxite, nepheline, kaolinite, etc.) in aluminumfree compounds. The efficiency of the hydrochemical technology depends on the activities of calcium oxide or its compounds introduced into the alkaline aluminosilicate slurry. In this paper, we considered the effects of different ...
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The Pedersen process was commercialized and is a high temperature (molten state) process that can separate iron and calcium aluminate slag . The method is regarded to be more material efficient and flexible in terms of the raw materials qualification to produce alumina as it can holistically utilize the bauxite or other alumina sources and ...
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The Utilization of Bauxite Residue with a CalciteRich Bauxite Ore in the Pedersen Process for Iron and Alumina Extraction Original Research Article Open access Published: 08 March 2021 52, ( 2021 ) Download PDF You have full access to this open access article Metallurgical and Materials Transactions B Aims and scope Submit manuscript
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Bauxite residue is a kind of strong alkaline waste produced in the production of alumina. Its longterm storage poses a potential threat to the environment. With the tightening of environment policies in various countries, the strong alkalinity of bauxite residue has become a bottleneck restricting .
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1. Introduction. The characteristics of Chinese bauxite are high alumina, high silica, low ferrite, and middle and lowgrade diasporic bauxite (Niu, 2003, Yang, 2006).Consequently a combination process (Gu, 2004, Ai and Cheng, 2002) is mainly used to produce alumina in China, in which the flow is complicated and the energy consumption is Bayer process is an economical process with ...
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Bauxite containing less than 50% Al 2 O 3 is called lowgrade bauxite ore, which is generally used for the production of aluminum appliances such as abrasives, ceramics, and refractories . The presence of impurities, including silica, iron oxides, and calcium contribute to the bauxite being classified as a lowgrade ore.
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Overall, the bauxitebased defluoridation process described here offers a method that is potentially (1) effective at remediating fluoride contaminated groundwater, (2) affordable to impoverished s, (3) easy to operate and maintain without skilled labor, (4) culturally appropriate, and (5) widely available in fluorideaffected regions w...
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The alkaline release kinetics and response relationship of NA with respect to the process of bauxite residue neutralization were explored in this study. ... and C 1s to higher values were also found in the NA treated bauxite residue. Moreover, the calcium in the bauxite residue could react with NA to form "bridges" between organic matter ...
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The hydrometallurgy process of the "calcificationcarbonation method" (CCM; process flowchart shown in Fig. 1) was proposed (Zhang et al., 2017; Zhang et al., 2013; Lu et al., 2014; Lu et al., 2017) to convert the hydrated sodium aluminosilicate phase in Bayer red mud to CaO·SiO 2 and CaCO the calcification process, siliconcontaining phases (such as kaolinite in bauxite) are ...
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The Pedersen process is an alternative process for the production of alumina. Initially, bauxite ores, or other aluminous materials, are smelted with lime to produce pig iron and a slag of mainly calcium aluminate composition. The latter is subsequently leached in Na 2 CO 3 solutions to extract alumina hydrate.
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The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100::, reduction temperature of 1450°C and reduction time of ... smelting process was used to recover iron and calcium aluminate slag from highferrous bauxite. The reduction reaction mechanism is expressed by the following equations
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In general, a national acceptable synthesis method involves a twostep method where the bauxite, hydrochloric acid and calcium aluminate are used as raw materials to prepare liquid PAC [5,6]. And, in China, PAC is also based on those process to produce, however, which resulted in generation of large volumes of very acidic residue called ...
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The sinter process is widely used to process the poorgrade diasporic bauxite ores with A/S below 7, in China and Russia, by sintering the bauxite ore with sodium carbonate and limestone to form sodium aluminate and calcium silicate. In the process, the sinter is then leached with water, caustic soda solution, and recycled liquor to dissolve ...
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This breakthrough has broadened the available bauxite reserves and effectively mitigated the harmful effects of SiO 2 during the Bayer leaching process while minimizing bauxite residue emissions. Calciumsilica slag (CSS) emerges as a solid residue generated during the chemical predesilication of medium and lowgrade bauxite.
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[Show full abstract] process conditions were the bauxite/anthracite/slaked lime weight ratio of 100::, reduction temperature of 1450°C and reduction time of 20 min. Under these ...
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Calcium was introduced to bauxite residue to form leachable calcium aluminate phases with the existing alumina in bauxite residue. This involved the addition of either CaCO 3 or a mixture of CaO ...
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This process involves the separation of alumina from unwanted components such as iron, titanium, silica, calcium, vanadium, manganese, etc., in bauxite. In this process, bauxite is heated along with the caustic soda at high pressure (~30 atm), resulting in the formation of sodium aluminate (reactions (1)(4) ) ( Gil, 2005; Ma et al ., 2009 ).
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The main minerals in the reduction product from the ironaluminum symbiotic ore obtained by the lowcalcium reduction process are Fe, NaAlO 2, Na 2 CaSiO 4 and NaAlSiO 4, and the iron metallization efficiency, the leaching efficiency of Al 2 O 3 and the content of iron in the concentrate are %, % and % respectively under the ...
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