Aluminum Hydroxide Impurities Occlusions and Contamination Sources

Dobra, Gheorghe; Garcia-Granda, Santiago; Iliev, Sorin; Cotet, Lucian; Iosif, Hulka; Negrea, Petru; Duteanu, Narcis; Boiangiu, Alina; Filipescu, Laurentiu

Gheorghe Dobra, Santiago Garcia-Granda, Sorin Iliev, Lucian Cotet, Hulka Iosif, Petru Negrea, Narcis Duteanu, Alina Boiangiu, Laurentiu Filipescu

Aluminum Hydroxide Impurities Occlusions and Contamination Sources

Abstract:

This paper is reporting the data concerning impurities occlusion in the dried, milled and classified aluminum hydroxide, the sources of contamination and the ways to control the purity of classified aluminum hydroxide as raw material for special aluminas. Mainly, all the micronic size particles, floating in the super-saturated Bayer liquors, are potential sources of occluded impurities in the aluminum hydroxide particles. There are several mechanisms for embedding the impurities in crystalline substances. Of these, most probable ones in the Bayer alumina process are: a) occlusion of the spent liquor drops containing impurities inside the polycrystalline aluminum hydroxide congregates; b) hetero-nucleation of aluminum hydroxide on the surface of particles or colloids containing one or more impurities (the foreign particles are seized inside a crystals or inside of a crystalline multi-particulate association); c) incorporation of available ions or molecule reactive fragments in the poor crystalline structures of aluminum hydroxide after nucleation, during different growth stages of all already aggregated particles, under certain super-saturations. d) building up bridges between the scanty aggregated particles or filling the inside hollows of these aggregates with new quickly crystallized material, including the particulate impurities, mainly, during large fluctuations of the super-saturation. Using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy EDS (Apollo SSD detector, EDAX), the contributions of each of these mechanisms can be investigated simply and assumed from the collected data. It was shown that well crystallized phases originating directly from bauxite (like the aluminum substituted goethite and substituted hematite, rutile or quartz), as well as the well as the crystallized new born phases during specific Bayer reactions (like cancrinite, are not promoting directly the impurities occlusion. Poor crystalline phases (like sodalite and katoite or other secondary phases and their micronic size fragments are really sustaining impurities occlusion through all the acknowledged mechanisms.

Keywords:
alumina hydrate; bauxite residue; impurities; mineralogical phases; occlusion; microscopy

Issue: 2020, Volume 71, Issue 9

Pages: 65-76

Publication date: 2020/9/5

https://doi.org/10.37358/RC.20.9.8318

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This article is published under the Creative Commons Attribution 4.0 International License

Citation Styles

Cite this article as:
DOBRA, G., GARCIA-GRANDA, S., ILIEV, S., COTET, L., IOSIF, H., NEGREA, P., DUTEANU, N., BOIANGIU, A., FILIPESCU, L., Aluminum Hydroxide Impurities Occlusions and Contamination Sources, Rev. Chim., 71(9), 2020, 65-76.

Vancouver
Dobra G, Garcia-Granda S, Iliev S, Cotet L, Iosif H, Negrea P, Duteanu N, Boiangiu A, Filipescu L. Aluminum Hydroxide Impurities Occlusions and Contamination Sources. Rev. Chim.[internet]. 2020 Sep;71(9):65-76. Available from: https://doi.org/10.37358/RC.20.9.8318

APA 6th edition
Dobra, G., Garcia-Granda, S., Iliev, S., Cotet, L., Iosif, H., Negrea, P.,... Filipescu, L. (2020). Aluminum Hydroxide Impurities Occlusions and Contamination Sources. Revista de Chimie, 71(9), 65-76. https://doi.org/10.37358/RC.20.9.8318

Harvard
Dobra, G., Garcia-Granda, S., Iliev, S., Cotet, L., Iosif, H., Negrea, P., Duteanu, N., Boiangiu, A., Filipescu, L. (2020). 'Aluminum Hydroxide Impurities Occlusions and Contamination Sources', Revista de Chimie, 71(9), pp. 65-76. https://doi.org/10.37358/RC.20.9.8318

IEEE
G. Dobra, S. Garcia-Granda, S. Iliev, L. Cotet, H. Iosif, P. Negrea, N. Duteanu, A. Boiangiu, L. Filipescu, "Aluminum Hydroxide Impurities Occlusions and Contamination Sources". Revista de Chimie, vol. 71, no. 9, pp. 65-76, 2020. [online]. https://doi.org/10.37358/RC.20.9.8318

Text
Gheorghe Dobra, Santiago Garcia-Granda, Sorin Iliev, Lucian Cotet, Hulka Iosif, Petru Negrea, Narcis Duteanu, Alina Boiangiu, Laurentiu Filipescu,
Aluminum Hydroxide Impurities Occlusions and Contamination Sources,
Revista de Chimie,
Volume 71, Issue 9,
2020,
Pages 65-76,
ISSN 2668-8212,
https://doi.org/10.37358/RC.20.9.8318.
(https://revistadechimie.ro/Articles.asp?ID=8318)
Keywords: alumina hydrate; bauxite residue; impurities; mineralogical phases; occlusion; microscopy

RIS
TY - JOUR
T1 - Aluminum Hydroxide Impurities Occlusions and Contamination Sources
A1 - Dobra, Gheorghe
A2 - Garcia-Granda, Santiago
A3 - Iliev, Sorin
A4 - Cotet, Lucian
A5 - Iosif, Hulka
A6 - Negrea, Petru
A7 - Duteanu, Narcis
A8 - Boiangiu, Alina
A9 - Filipescu, Laurentiu
JF - Revista de Chimie
JO - Rev. Chim.
PB - Revista de Chimie SRL
SN - 2668-8212
Y1 - 2020
VL - 71
IS - 9
SP - 65
EP - 76
UR - https://doi.org/10.37358/RC.20.9.8318
KW - alumina hydrate
KW - bauxite residue
KW - impurities
KW - mineralogical phases
KW - occlusion
KW - microscopy
ER -

BibTex
@article{RevCh2020P65,
author = {Dobra Gheorghe and Garcia-Granda Santiago and Iliev Sorin and Cotet Lucian and Iosif Hulka and Negrea Petru and Duteanu Narcis and Boiangiu Alina and Filipescu Laurentiu},
title = {Aluminum Hydroxide Impurities Occlusions and Contamination Sources},
journal = {Revista de Chimie},
volume = {71},
number = {9},
pages = {65-76},
year = {2020},
issn = {2668-8212},
doi = {https://doi.org/10.37358/RC.20.9.8318},
url = {https://revistadechimie.ro/Articles.asp?ID=8318}
}

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