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Title: THERMAL DEHYDRATION OF NATURAL HYDROUS FERRIC SULFATE Fe(SO4)(OH)?2H2O

THERMAL DEHYDRATION OF NATURAL HYDROUS FERRIC SULFATE Fe(SO4)(OH)?2H2O
N. Zayakina;M. Kudrin;V. Fridovsky
1314-2704
English
20
1.1
Thermal dehydration of a natural hydrous ferric sulfate Fe(SO4)(OH)?2H2O was studied using x-ray-phase and thermal analyses. This mineral was found in the hypergenesis zone of the Khangalas gold deposit, Eastern Yakutia, Russia. A comparative analysis of the sample with known hypergenic hydrous ferric sulfates with a similar Fe2O3:SO3 ratio close to 1:1 was performed. The dissimilarities between the founded mineral and its possible polymorphs ? butlerite and parabutlerite are identified. The mineral is less stable and begins to break down at 60 °C. Water loss in the first two endothermic peaks (120 and 255 °C) is about 16%, which is close to the loss of two H2O molecules. At 120 °C a new previously unknown phase X is formed, which persists to temperatures of ~255-280 °C. No analogs to the X ray pattern of this phase could be found. The interplanar distances and intensities of its main lines are as follows: d (I) -9.3(100), 4.66(25), 3.53(42), 3.32(10), 2.144(8) A. It is likely that this phase is a hydrous sulfate Fe(SO4)(OH)·0.5H2O, that has not yet been identified in nature. Completely water and OH group disappear by 450 °C, while the mass loss is ~24 %. For temperatures of ~300 °C and higher, the dehydration processes for all the minerals of the studied group are almost identical. When further heating occurs, the mineral is completely dehydrated and anhydrous ferrous sulfates are formed. The final stage of the decomposition of anhydrous ferrous sulfate after heating the sample to 700 °C ? hematite formation.
conference
20th International Multidisciplinary Scientific GeoConference SGEM 2020
20th International Multidisciplinary Scientific GeoConference SGEM 2020, 18 - 24 August, 2020
Proceedings Paper
STEF92 Technology
International Multidisciplinary Scientific GeoConference-SGEM
SWS Scholarly Society; Acad Sci Czech Republ; Latvian Acad Sci; Polish Acad Sci; Russian Acad Sci; Serbian Acad Sci & Arts; Natl Acad Sci Ukraine; Natl Acad Sci Armenia; Sci Council Japan; European Acad Sci, Arts & Letters; Acad Fine Arts Zagreb Croatia; C
863-870
18 - 24 August, 2020
website
cdrom
6764
natural sulfate Fe3+(SO4)(OH)?2H2O; butlerite; parabutlerite; thermal decomposition; x-ray phase and thermal analysis; Khangalas deposit; Eastern Yakutia.