The Constitution, Reactivity and Thermal Change of Phosphate Ores

Ando, Jumpei; Matsuno, Seiichi

doi:10.1246/bcsj.39.1915

Cited by 7 publications

(1 citation statement)

References 3 publications

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“…Пробы 1и 2 имеют приблизительно одинаковое количество Р2ОS, но различаются по содержанию примесей. Например, проба 1 с северной части участка Рягавере весьма богата пиритом (который составляет 60% общего Ре 2 0з) и органическим веществом, окисляемость [ 7 ] концентрата превышает 40 единиц. В пробе 2 из средней части участка магния больше, чем в пробе 1, пирит и органическое вещество присутствуют в незначительном количестве, зато непиритиого железа больше.…”

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Состав И Кислотная Переработка Фосфорита Участка Рягавере

Aasamäe¹,

Veiderma²

1982

Proceedings of the Academy of Sciences of the Estonian SSR. Che

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Состав И Кислотная Переработка Фосфорита Участка Рягавере

Aasamäe¹,

Veiderma²

1982

Proceedings of the Academy of Sciences of the Estonian SSR. Che

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Calcination of phosphate in impinging streams. Part I. development, theory and modeling

Ziv

Tamir

1993

Can. J. Chem. Eng.

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An impinging‐stream reactor, developed and tested for calcination of phosphate with low organic matter content, has proven to be an efficient device for conducting this process. Modeling of the calcination process has been done along two lines. Considering a single particle and assuming that calcination rate is controlled by the heat transfer in the particle, resulted in a criterion for testing the effect of temperature on the enrichment of P205 and other phenomena. Performing a heat balance on the reactor and on the particle, and incorporating physical concepts, led to correlations with only one adjustable parameter for the conversion of carbonates as a function of the operating parameters. The major conclusion drawn from implementation of the model was that phosphate calcination is governed by the internal resistance of the particle to the heat transfer. The calcination efficiency results, as well as the practical experience gained in this study, indicated that the impinging‐stream calciner may provide a promising tool for phosphate enrichment, and more generally, for processes involving gas‐solid contact at high temperatures.

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Behaviour of uranium during phosphate ore calcination

Stein

Starinsky

Kolodny

1982

J. Chem. Technol. Biotechnol.

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During industrial calcination of phosphate rock, uranium is mobilised with changes both in location and oxidation state. Fission track micromapping of uranium under the microscope has been employed to study the precise distribution of uranium within the samples. Oxidation state ratios of U(IV) to U(V1) were determined by chemical separation followed by delayed neutron activation. The calcination process was studied both in the laboratory and in a full-scale production kiln of the Oron plant (Israel). The phosphate ore contains about 100 parts of of uranium, and U(IV) comprises 3540% of the total U present. The uranium which was not extractable in weak acids, was evenly distributed in the apatite rock components. The study revealed that the following changes occur during the calcination process: (a) carbonate-fluorapatite loses COZ, and recrystallises to fluorapatite. The recrystallisation process intensifies with increasing temperature. (b) Around 600°C all the uranium is oxidised to the hexavalent state. (c) Migration of uranium in the apatite fragments initiates at 800°C. On increase of temperature to around 9oo°C, it forms uraniumrich phases in which it reaches 1-2 %. The uranium-rich phases exhibit different solubilities in dilute acids, in some cases enabling its preferential leaching from the rock. Other U-rich phases are extremely insoluble (posslbly fluorite, Ca-silicates) even in phosphoric acid, lowering extraction efficiency. Extraction yields can be improved by addition of salts (e.g. NazC03) which prevent the formation of insoluble U-rich phases.

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The Constitution, Reactivity and Thermal Change of Phosphate Ores

Abstract: Tests were made on twenty-five samples of phosphate ores from all over the world deposits. All of the samples consisted of apatite, plus small amounts of calcite and other minerals. The

Cited by 7 publications

References 3 publications

Состав И Кислотная Переработка Фосфорита Участка Рягавере

Состав И Кислотная Переработка Фосфорита Участка Рягавере

Calcination of phosphate in impinging streams. Part I. development, theory and modeling

Behaviour of uranium during phosphate ore calcination

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