The Amex Process for Extracting Thorium Ores with Alkyl Amines

Crouse, D.J.; Brown, K.B.

doi:10.1021/ie50600a030

Cited by 25 publications

(10 citation statements)

References 4 publications

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“…Amine extractants have been employed in the AMEX process, which was developed in the late 1950s, for extracting radioactive elements from REE-bearing minerals. In this process, the amine extractants are mixed with a sulfate leach liquor produced from monazite sands [57]. Thorium is first extracted with a primary amine (reaction 15) followed by a nitric acid stripping step.…”

Section: Solvent Extraction With Amine Extractantsmentioning

confidence: 99%

Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals

García

Latifi

Amini

et al. 2020

Metals

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Rare earth elements (REE), originally found in various low-grade deposits in the form of different minerals, are associated with gangues that have similar physicochemical properties. However, the production of REE is attractive due to their numerous applications in advanced materials and new technologies. The presence of the radioactive elements, thorium and uranium, in the REE deposits, is a production challenge. Their separation is crucial to gaining a product with minimum radioactivity in the downstream processes, and to mitigate the environmental and safety issues. In the present study, different techniques for separation of the radioactive elements from REE are reviewed, including leaching, precipitation, solvent extraction, and ion chromatography. In addition, the waste management of the separated radioactive elements is discussed with a particular conclusion that such a waste stream can be employed as a valuable co-product.

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Section: Solvent Extraction With Amine Extractantsmentioning

confidence: 99%

Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals

García

Latifi

Amini

et al. 2020

Metals

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“…Unlike uranium, thorium can be easily extracted chiefly from monazite sands through a complex multi-stage process (Crouse and Brown 1959). However, there is no international or standard classification for thorium resources and identified Th resources do not have the same meaning in terms of classification as identified U resources.…”

Section: Extraction Potentialitymentioning

confidence: 99%

Laboratory Enrichment of Radioactive Assemblages and Estimation of Thorium and Uranium Radioactivity in Fractions Separated from Placer Sands in Southeast Bangladesh

et al. 2014

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The present study reports the likely first attempt of separating radioactive minerals for estimation of activity concentration in the beach placer sands of Bangladesh. Several sand samples from heavy mineral deposits located at the south-eastern coastal belt of Bangladesh were processed to physically upgrade their radioactivity concentrations using plant and laboratory equipment. Following some modified flow procedure, individual fractions were separated and investigated using gamma-ray spectrometry and powder-XRD analysis. The radioactivity measurements indicated contributions of the thorium and uranium radioactive series and of 40 K. The maximum values of 232 Th and 238 U, estimated from the radioactivity of 208 Tl and 234 Th in secular equilibrium, were found to be 152,000 and 63,300 Bq/kg, respectively. The fraction of the moderately conductive part in electric separation contained thorium predominantly, while that of the non-conductive part was found to be uranium rich. The present arrangement of the pilot plant cascade and the fine tuning of setting parameters were found to be effective and economic separation process of the radioactive minerals from placer sands in Bangladesh. Probable radiological impacts and extraction potentiality of such radioactive materials are also discussed.

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“…Mechanically and electro-magnetically separated monazite from placer deposits are processed by two opening routes, acid method and alkaline method (Barghusen & Smutz, 1958;Crouse & Brown, 1959). In the former method, the ore is digested with conc.…”

Section: Monazite Processingmentioning

confidence: 99%

Thorium minerals in Sri Lanka, history of radioactivity and thorium as a future energy source: a compendium to commemorate the International Year of Chemistry 2011

Tennakone

2011

J. Natn. Sci. Foundation Sri Lanka

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The discovery of radioactivity more than a century ago and vigorous research on the subject thereafter has transformed the world scientifically and technologically through a deeper understanding of the nature of matter. Two stalwarts among the illustrious pioneers in this field were Lord Ernest Rutherford and Madame Marie Curie. Both were physicists by training and both won the Nobel Prize for Chemistry. While Rutherford's work was more inclined towards physics, enabling elucidation of the structure and mechanics of the atom, Curie's discoveries instantly catalyzed a revolution in chemistry. The year 2011, designated as the International Year of Chemistry, celebrates the centennial anniversary of award of the Chemistry Nobel Prize to Marie Curie. When Marie Curie separated radium from pitchblende, the curious researchers and amateurs started turning stones around looking for pitchblende and other radioactive minerals. In this endeavour, a British planter in Sri Lanka (then Ceylon) collected heavy rock samples, similar in appearance to pitchblende, and dispatched them to two eminent researchers pursuing studies on radioactivity in Britain. Analysis by chemists in Britain and subsequent prospecting by the then Ceylon Geological Survey enabled identification of thorium oxide thorium and silicate minerals, thorianite and thorite, containing a very high percentage of thorium. A number of major discoveries in radioactivity by outstanding pioneers in this field have been conducted using Ceylon thorianite and thorite. Most reputed physics and chemistry journals in the first three decades of the twentieth century carry articles on these discoveries making conspicuous references to Ceylon thorium minerals. The International Year of Chemistry is an appropriate moment to review the history of radioactivity in relation to thorium minerals of Sri Lanka. Coincidently, Sri Lanka and several other countries are currently focussing much attention on the use of thorium as a safe, environmentally benign and lasting source of energy. This work examines discoveries in radioactivity made by pioneers of this field, using Ceylon thorium minerals, giving historical anecdotes on use of Sri Lankan minerals in understanding fundamental properties of matter. The important aspects of uranium-thorium mineral chemistry, formation of radioactive mineral sand placer deposits and generation of thorium based nuclear energy are also discussed, because of current relevance of these topics to Sri Lanka.

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The Amex Process for Extracting Thorium Ores with Alkyl Amines

Cited by 25 publications

References 4 publications

Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals

Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals

Laboratory Enrichment of Radioactive Assemblages and Estimation of Thorium and Uranium Radioactivity in Fractions Separated from Placer Sands in Southeast Bangladesh

Thorium minerals in Sri Lanka, history of radioactivity and thorium as a future energy source: a compendium to commemorate the International Year of Chemistry 2011

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