Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (3)

Search Parameters:
Keywords = coarse gibbsite

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
17 pages, 8378 KB  
Article
Enhanced Precipitation of Gibbsite from Sodium Aluminate Solution by Adding Agglomerated Active Al(OH)3 Seed
by Andrei Shoppert, Dmitry Valeev, Konstantin Alekseev and Irina Loginova
Metals 2023, 13(2), 193; https://doi.org/10.3390/met13020193 - 18 Jan 2023
Cited by 6 | Viewed by 5029
Abstract
The addition of active seed for increasing the precipitation rate leads to the formation of fine Al(OH)3 particles that complicates separation of solid from the mother liquor. In this study, the enhanced precipitation of coarse Al(OH)3 from sodium aluminate solution using [...] Read more.
The addition of active seed for increasing the precipitation rate leads to the formation of fine Al(OH)3 particles that complicates separation of solid from the mother liquor. In this study, the enhanced precipitation of coarse Al(OH)3 from sodium aluminate solution using active agglomerated seed was investigated. Aluminum salt (Al2(SO4)3) were used for active agglomerated seed precipitation at the initial of the process. About 50% of precipitation rate was obtained when these agglomerates were used as a seed in the amount of 20 g L−1 at 25 °C within 10 h. The agglomerated active seed and precipitate samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). SEM images showed that agglomerates consist of flake-like particles that can be stick together by bayerite (β-Al(OH)3) acting as a binder. The precipitation temperature above 35 °C and the high concentration of free alkali (αk = 1.645Na2Ok/Al2O3 > 3) lead to the agglomerates refinement that can be associated with the bayerite dissolution. Full article
(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy—2nd Edition)
Show Figures

Figure 1

12 pages, 4677 KB  
Article
Processing of Low-Quality Gibbsite-Kaolinite Bauxites
by Symbat Dyussenova, Rinat Abdulvaliyev, Ata Akcil, Sergey Gladyshev and Galiya Ruzakhunova
Metals 2022, 12(6), 1030; https://doi.org/10.3390/met12061030 - 17 Jun 2022
Cited by 7 | Viewed by 3097
Abstract
The results of studies on the processing of gibbsite-kaolinite bauxite are presented. The developed technology includes preliminary chemical activation and thermal transformation during enrichment to obtain a concentrate suitable for processing by the Bayer method. As a result of the chemical activation of [...] Read more.
The results of studies on the processing of gibbsite-kaolinite bauxite are presented. The developed technology includes preliminary chemical activation and thermal transformation during enrichment to obtain a concentrate suitable for processing by the Bayer method. As a result of the chemical activation of gibbsite-kaolinite bauxite in a solution of sodium bicarbonate, a change in the phase composition occurs, which made it possible to improve the results of gravity enrichment with the production of a coarse-grained gibbsite fraction. The transformation of bauxite in the temperature range of 900–1000 °C is explained by the decomposition reactions of siderite, gibbsite, kaolinite, calcite, dolomite and sodium ferro-sulfide oxide, as well as the formation of sodium aluminosilicate, hematite, quartz and the chemically stable phase of corundum. The optimum firing temperature of bauxite is 950 °C, after which, as a result of alkaline treatment during chemical enrichment, the extraction of SiO2 into solution was 74.9%. A silicon modulus of enriched bauxite 10.9 units was obtained. As a result of the autoclave leaching of gibbsite-kaolinite bauxite after a two-stage enrichment, the maximum extraction of alumina into solution was 87.4%. The yield of red mud during the processing of bauxite enriched and calcined at 950 °C was 37.62%. During the autoclave leaching of bauxite without enrichment, the yield of red mud was 71%. Full article
Show Figures

Figure 1

10 pages, 9274 KB  
Article
Formation of Phases and Porous System in the Product of Hydrothermal Treatment of χ-Al2O3
by Svetlana R. Egorova, Aliya N. Mukhamed’yarova, Oksana V. Nesterova, Yuqing Zhang, Juliya D. Skibina and Alexander A. Lamberov
Coatings 2018, 8(1), 30; https://doi.org/10.3390/coatings8010030 - 11 Jan 2018
Cited by 9 | Viewed by 5516
Abstract
The presence of χ-Al2O3 resulting from thermal decomposition gibbsite as part of alumina catalysts is unfavorable because of its acid characteristics. One of the available techniques of χ-Al2O3 removal is crystallization under hydrothermal conditions into boehmite, which [...] Read more.
The presence of χ-Al2O3 resulting from thermal decomposition gibbsite as part of alumina catalysts is unfavorable because of its acid characteristics. One of the available techniques of χ-Al2O3 removal is crystallization under hydrothermal conditions into boehmite, which is a main precursor of active γ-Al2O3. The influence of products of the hydrothermal treatment of χ-Al2O3 obtaining in result of thermal decomposition gibbsite under T = 150–200 °C, P = 0.5–1.5 MPa and pH = 4.0–9.2 were studied. The hydrothermal treatment products in these conditions are gibbsite and boehmite phases which are formed coincidently by parallel ways. In the alkaline medium at pH = 8.0–9.2 three-dimensional parallelepiped boehmite crystals with the edge length > 200 nm are formed, at pH = 4.0 two-dimensional rhombic-shaped plates with thickness 20–100 nm and with the edge length ~ 80–500 nm are formed. Crystallization of coarse boehmite particles promotes the formation of large and closed mesoporous. Full article
Show Figures

Graphical abstract

Back to TopTop