Journal of Thermal Analysis and Calorimetry
Volume/Issue:
Volume 92: Issue 3
Calorimetric study of dissolution kinetics of phosphorite in diluted acetic acid
Authors:
T. Vaimakis University of Ioannina Department of Chemistry P.O. Box 1186 45110 Ioannina Greece

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E. Economou University of Ioannina Department of Chemistry P.O. Box 1186 45110 Ioannina Greece

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C. Trapalis Institute of Materials Science National Center for Scientific Research ‘Demokritos’ 153 10 Athens Greece

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Pages:
783–789
Online Publication Date:
02 Jul 2008
Publication Date:
01 Jun 2008
Article Category:
Research Article
DOI:
https://doi.org/10.1007/s10973-007-8025-8
Keywords:
calorimetric; kinetic mechanism; phosphorite dissolution
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Abstract  

In this report, we present a thermodynamic and kinetic study of the selective dissolution of calcite from low-grade phosphate ores (Epirus area, Greece) by dilute acetic acid at isothermal conditions. A twin calorimeter with two identical membrane vessels, for the acid dissolution process, and for the reference was used. The curves of rate vs. time of the phosphorite dissolution for various temperatures show that the maximum (.qmax) was increased, whereas the time (tpeak) to achieve the corresponding .qmax values was decreased, as the experimental temperature was increased. The dissolution enthalpy was increased from 13.1 to 16.7 kJ mol−1, as the experimental temperature was increased from 10.0 to 28.0°C. The chemical analysis of the supernatant solutions shows that the main process was the calcite dissolution. The reaction model with general form, ln(1/(1-X))=ktm, was found to fitted the experimental data regardless of the experimental temperature. These results were assigned in the presence of two different kinds of particles in the phosphorite. The activation energy of the dissolution process was found 69.7 kJ mol−1. The SEM micrographs of acid dissolution samples showed two different textures after acid dissolution.

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Cover Journal of Thermal Analysis and Calorimetry
Journal of Thermal Analysis and Calorimetry
Print ISSN:
1388-6150
Online ISSN:
1572-8943

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Journal of Thermal Analysis and Calorimetry
Language English
Size A4
Year of
Foundation		 1969
Volumes
per Year		 1
Issues
per Year		 24
Founder Akadémiai Kiadó
Founder's
Address		 H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
Publisher Akadémiai Kiadó
Springer Nature Switzerland AG
Publisher's
Address		 H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible
Publisher		 Chief Executive Officer, Akadémiai Kiadó
ISSN 1388-6150 (Print)
ISSN 1588-2926 (Online)

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