Thermochemical activation of hydrated aluminosilicates and its importance for alumina production

Дубовиков, О. А.; Brichkin, V. N.; Ris, Aleksandra; Sundurov, Aleksandr

doi:10.17580/nfm.2018.02.02

Cited by 12 publications

(10 citation statements)

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“…Technological processes associated with the processing of minerals, in particular, apatite-nepheline raw materials, as well as metallurgical and chemical production, lead to the formation of large amounts of waste, which is an environmental problem of mineral complexes. One of the significant problems is the emission of process gases into the atmosphere containing toxic substances, including sulfur-containing compounds. − …”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Characteristics of the Hydrogen Sulfide Sorption Process by Ferromanganese Materials

et al. 2022

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The work analyzes hydrogen sulfide sorption from model gas mixtures containing H 2 S from 1.25 × 10 −3 to 1.28 × 10 −4 mol/L under static conditions at temperatures 253 and 298 K on the raw manganese ore of the Ulu-Telyak deposit (Bashkortostan, Russia), manganese(IV) oxide, and manganese(IV) and iron(III) oxide mixtures. The thermodynamic models for calculating the equilibrium constants and Gibbs energy changes were analyzed. The sorption isotherms were described by the Langmuir, Freundlich, Temkin, and Dubinin−Radushkevich models. The value of enthalpy H (253 298) 0 Δ − of hydrogen sorption on the ore was −68.98 ± 3.45 kJ/mol and those on model mixtures Mn 4 + Fe 2 O 3 and MnO 4 were ±12.20 kJ/mol and −103.826 ± 5.19 kJ/ mol, respectively, and the entropies of the hydrogen sulfide sorption process on three manganese materials at 253 K were calculated.The limiting capacity values of manganese materials at 253 and 298 K were obtained. The morphological analysis of the ore samples, Mn 4 + Fe 2 O 3 , and MnO 4 , before and after hydrogen sulfide sorption, was carried out at 253 K. The obtained thermodynamic parameters determine the advantage of using the raw manganese ore over pure oxides, which characterizes its effective practical application in the desulfurization process.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic Characteristics of the Hydrogen Sulfide Sorption Process by Ferromanganese Materials

et al. 2022

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“…The emission of waste gases containing toxic substances, including sulfur-containing compounds, is a serious environmental problem of the metallurgical industry [1][2][3][4][5][6]. Sorption methods are still effective in the field of the air environment cleaning process.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Features of the Hydrogen Sulfide Sorption on the Ferro-Manganese Material

Cheremisina¹,

Черемисина

Ponomareva

et al. 2021

Metals

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The kinetics of hydrogen sulfide sorption by the surface of a ferromanganese material containing in its composition a mixture of iron (II) and (III) oxides FeO × Fe2O3, takanelite (Mn, Ca) Mn4O9 × 3H2O and quartz SiO2, and which is samples of unrefined ferromanganese ore, was studied in this work. Sorption rate constant and activation energy constant values were calculated. The catalytic effect of iron (III) oxide was established, the presence of which in natural material contributes to a decrease in the H2S sorption activation energy. Based on the results of X-ray phase and chromatographic analysis methods, a chemical (redox) reaction of the conversion of hydrogen sulfide into elemental sulfur and H2O was revealed. The overall process rate is expressed in terms of the physical sorption stage and chemical transformation of the components; the influence of the rate of the third stage—reaction products desorption—on the overall rate of the process is taken into account. The limiting stage of the process is determined—a chemical reaction. The relation between the heat and the activation energy of the chemical transformation is used according to the Bronsted—Polanyi rule for catalytic processes. It was found that with an increase in the chemisorption heat, the activation energy of the chemisorption stage decreases and, as a consequence, its rate increases. The sorption process parameters were calculated—the Fe2O3 coverage degree with the initial substances and reaction products providing the maximum sorption rate, which can be a criterion for evaluating the catalytically active sites of the catalyst surface for carrying out catalytic reactions.

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“…Therefore, an achieving of the thermochemical activation by the addition of fluxing agents (i. e. Charcoal) to the kaolin-limestone mixtures in the sintering process would produce more low costeffectiveness and energy-efficiency by lowering the temperature limit of the phase transformation (i.e., dicalcium silicate C 2 S β to γ phases). Not only this, but also the charcoal addition extremely improving the physical surface properties of the self-disintegrated sinter powders and particles and hence enhancing the leaching process and maximizing the alumina percent recovery (Qiu et al, 2004;Sizyakov et al, 2013a;Sizyakov et al, 2013b;Sizyakov & Brichkin, 2018;Dubovikov et al, 2018;. In addition to the charcoal, previous researches indicated that the common other additive of inorganic fluxing agents were MgO, A1 2 O 3 , Fe 2 O 3 , BaO, B 2 O 3 , Na 2 O, K 2 O, P 2 O 5 , MnO 2 and Cr 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

“…β-C 2 S to γ-phases). Moreover, the addition of charcoal would significantly improve the surface properties of the self-disintegrated sinter powders and particles and hence would increase leaching and maximize the alumina percentage recovery (APR; Qiu et al, 2004;Sizyakov et al, 2013aSizyakov et al, , 2013bDubovikov et al, 2018;Sizyakov & Brichkin, 2018;Li et al, 2019). Previous work showed that other compounds such as MgO, Al 2 O 3 , Fe 2 O 3 , BaO, B 2 O 3 , Na 2 O, K 2 O, P 2 O 5 , MnO 2 and Cr 2 O 3 , present either as chemical impurities or as fluxing additives to kaolin, were unfavourable because they stabilized the β-C 2 S phase and hence prevented self-disintegration (Wang et al, 2011;Yu et al, 2012Yu et al, , 2014Yu et al, , 2019Guo et al, 2014;Yan et al, 2017;Bazhirov et al, 2020).…”

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confidence: 99%

Enhanced alumina extraction from kaolin by thermochemical activation using charcoal

et al. 2021

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Thermochemical activation of hydrated aluminosilicates and its importance for alumina production

Cited by 12 publications

References 0 publications

Thermodynamic Characteristics of the Hydrogen Sulfide Sorption Process by Ferromanganese Materials

Thermodynamic Characteristics of the Hydrogen Sulfide Sorption Process by Ferromanganese Materials

Kinetic Features of the Hydrogen Sulfide Sorption on the Ferro-Manganese Material

Enhanced alumina extraction from kaolin by thermochemical activation using charcoal

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