Rare-earth elements, thermal history, and the colour of natural fluorites

1987 ◽  
Vol 24 (10) ◽  
pp. 2082-2088 ◽  
Author(s):  
D. L. Naldrett ◽  
Andre Lachaine ◽  
S. N. Naldrett
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Absorption Spectra ◽  
Thermal History ◽  
Colloidal Particles ◽  
Radioactive Elements ◽  
Purple Colour ◽  
Naturally Occurring ◽  
Ionizing Radiations ◽  
Photo Acoustic Spectroscopy

The contents of La and of all 13 naturally occurring rare-earth elements (REEs) in samples of natural fluorites were determined by neutron activation analysis. The samples were chosen to test the relation of REE content to colour. Total REE contents of the samples ranged from 3.46 to 97.2 ppm; the range of the least abundant REE, Lu, was 0.031–0.57 ppm and the range of the most abundant REE, Ce, was 0.94–33.3 ppm. No relation was found between the absolute amounts nor the enrichment or depletion of a particular REE and colour. The absorption spectra from 400 to 700 nm were determined by photo-acoustic spectroscopy using a few milligrams of powdered fluorite sample. Optical absorption spectra were obtained for all samples including those that were too small or too opaque for transmission or reflectance methods. The absorption maxima obtained are similar to those reported by others for samples of similar colours. It is concluded that ionizing radiations from incorporated radioactive elements produce the divalent REE ions that account initially for purple colour. From the description given in the literature on the thermoluminescence of fluorites it is then shown that the thermal history can account for the ultimate colour. However, other factors, such as the presence of water vapour, oxygen, or hydrogen; variation in the growth rate of crystals; colloidal particles; and exposure to light, can contribute to the colour.

scholarly journals Assessment of Trace Elements in Soils and Sediments in the Abandoned Mercury Mine Site in Puerto Princesa City, Philippines

2021 ◽  
Vol 38 (2) ◽  
Author(s):  
Jessie Samaniego ◽  
Cris Reven Gibaga ◽  
Alexandria Tanciongco ◽  
Rasty Rastrullo
Keyword(s):  
Heavy Metals ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Contamination Factor ◽  
Area Measurement ◽  
Open Pit ◽  
Radioactive Elements ◽  
Mercury Mine ◽  
Naturally Occurring ◽  
Soil And Sediment

An abandoned mercury mine area in Puerto Princesa City, which was previously operated by Palawan Quicksilver Mines, Inc. (PQMI) from 1953 to 1976, is known for its unrehabilitated open-pit of mercury-rich rocks and exposed mine waste calcine stockpiles in the vicinity. In order to establish an understanding on the geology of the abandoned mercury mine deposit and to obtain clues in determining the possible metal pollutants in the area, measurement of trace element concentrations of soil and sediments collected from the PQMI vicinity were conducted. Soil and sediment samples were analyzed for heavy metals, rare-earth elements and naturally occurring radioactive elements and determined its contamination factor as part of risk assessment. Analytical results showed that aside from mercury, several heavy metals (nickel, chromium, manganese) were found to be anomalous due to the geology of the area. Statistical analyses show that chromium, nickel and antimony present the highest contamination factor among the sampling groups. Mercury is found to have negative bias with higher rare earth elements concentration but positively correlated with arsenic, antimony, and thallium. In general, there is low concentration of rare earth elements (except for scandium) in comparison with its respective average crustal concentration. Due to the nature of geology in the area, naturally occurring radioactive elements influence is also minimal. The results of this study, especially on the assessment of soil and sediment pollutants, are recommended as guidance to its mine rehabilitation.

scholarly journals Two-Step Solvent Extraction of Radioactive Elements and Rare Earths from Estonian Phosphorite Ore Using Nitrated Aliquat 336 and Bis(2-ethylhexyl) Phosphate

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 388
Author(s):  
Silvester Jürjo ◽  
Liis Siinor ◽  
Carolin Siimenson ◽  
Päärn Paiste ◽  
Enn Lust
Keyword(s):  
Rare Earth ◽  
Solvent Extraction ◽  
Rare Earth Elements ◽  
Toxic Elements ◽  
Downstream Processing ◽  
Liquid Extraction ◽  
Aliquat 336 ◽  
Radioactive Elements ◽  
Improved Method ◽  
Ph Values

Estonian phosphorite ore contains trace amounts of rare earth elements (REEs), many other d-metals, and some radioactive elements. Rare earth elements, Mo, V, etc. might be economically exploitable, while some radioactive and toxic elements should be removed before any other downstream processing for environmental and nutritional safety reasons. All untreated hazardous elements remain in landfilled waste in much higher concentration than they occur naturally. To resolve this problem U, Th, and Tl were removed from phosphorite ore at first using liquid extraction. In the next step, REE were isolated from raffinate. Nitrated Aliquat 336 (A336[NO3]) and Bis(2-ethylhexyl) Phosphate (D2EHPA) were used in liquid extraction for comparison. An improved method for exclusive separation of radioactive elements and REEs from phosphorite ore in 2-steps has been developed, exploiting liquid extraction at different pH values.

scholarly journals Development of methods for the recovery оf rare-earth elements from the mineral resources of the Arctic

2021 ◽  
Author(s):  
E. P. Lokshin ◽  
◽  
O. A. Tareeva ◽  
◽  
◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Raw Materials ◽  
Mineral Resources ◽  
The Arctic ◽  
Resource Saving ◽  
Apatite Concentrate ◽  
Naturally Occurring ◽  
Wide Range ◽  
Rare Earth Mineral

This paper summarizes the findings of the research aimed at the development of a new method for the integrated processing of naturally occurring and anthropogenic rare-earth raw materials based on the decomposition of rare-earth element (REE) concentrates in the presence of sulfocationite. Sorption and desorption of REE cations on a strongly acidic ion exchanger, sorbent regeneration, and REE recovery from eluates are discussed. A virtually zero-waste integrated process for apatite concentrate is proposed. The generalization of the research findings is aimed at demonstrating the prospects and universality of the proposed resource-saving and environmentally safe approach to the processing of various types of naturally occurring and anthropogenic rare-earth mineral feeds. The new methodology made it possible to develop a number of new hydrochemical processes united by a single approach, providing a qualitative increase in the processing performance of various types of rare-earth mineral feeds. The theoretical foundations of a unified approach to the processing of a wide range of minerals can significantly accelerate and cheapen the implementation of specific process circuits, significantly reduce reagent consumption and waste generation, simplify the separation of rare earth elements and impurities, and the separation of rare earth elements from naturally occurring radionuclides, fluorine, and phosphorus. The study was funded by the Kolarctic CBC 2014-2020 program, Project KO1030 SEESIMA — Supporting Environmental Economic and Social Impacts of Mining Activity.

scholarly journals Peningkatan Perolehan Uranium, Torium, dan Logam Tanah Jarang dalam Residu Pelarutan Parsial pada Pengolahan Monasit

EKSPLORIUM ◽  
2021 ◽  
Vol 42 (2) ◽  
pp. 141
Author(s):  
Novita Sari Fatihah ◽  
Mutia Anggraini ◽  
Afiq Azfar Pratama ◽  
Kurnia Setiawan Widana
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Metals ◽  
Ammonium Hydroxide ◽  
Deposition Process ◽  
Optimum Process ◽  
Process Conditions ◽  
Radioactive Elements ◽  
Partial Dissolution ◽  
Total Dissolution

ABSTRAK. Monasit merupakan mineral hasil samping pengolahan timah yang mengandung fosfat, logam tanah jarang, dan unsur radioaktif berupa uranium dan torium. Unsur-unsur tersebut dapat dimanfaatkan secara optimal jika terpisah satu dengan yang lainnya melalui proses pengolahan. Pengolahan monasit meliputi proses dekomposisi, pelarutan parsial, dan pengendapan. Pemisahan unsur logam tanah jarang dari unsur radioaktif dalam monasit dilakukan melalui proses pelarutan parsial, akan tetapi pemisahan tersebut belum optimal sehingga diperlukan proses lebih lanjut untuk meningkatkan perolehan unsur-unsur tersebut. Pada penelitian ini, proses tersebut dilakukan melalui dua metode yaitu pelarutan total dengan asam klorida (HCl) yang bertujuan untuk melarutkan semua unsur dalam endapan dan pengendapan dengan ammonium hidroksida (NH4OH) yang bertujuan untuk memisahkan unsur radioaktif dan unsur logam tanah jarang. Kedua metode tersebut dilakukan pada kondisi optimum proses dengan berbagai variasi pH, suhu, dan waktu. Berdasarkan hasil pengamatan diperoleh bahwa kelarutan optimum masing-masing unsur sebesar 67,6% uranium, 15,3% torium, dan 50,8% LTJ pada kondisi proses pelarutan pH 1, pada suhu 80°C selama 2 jam. Sedangkan pada proses pengendapan diperoleh recovery pengendapan masing-masing unsur sebesar 57% uranium, 75,7% torium, 4,8% logam tanah jarang pada kondisi pH 6. Berdasarkan data tersebut disimpulkan bahwa uranium, torium, dan logam tanah jarang dapat larut pada kondisi proses pelarutan pH 1, suhu 80°C selama 2 jam, dan dapat dipisahkan pada kondisi pH pengendapan 6.ABSTRACT. Monazite is a by-product of tin processing containing phosphate, rare earth elements, and radioactive elements such as uranium and thorium. These elements can be utilized optimally if separated from one another through processing. Monazite processing includes decomposition, partial dissolution, and precipitation processes. The separation of rare earth elements from radioactive elements in monazite is carried out through a partial dissolution process, but the separation is not optimal so that further processes are needed to increase the recovery of these elements. In this study, the process was carried out using two methods, namely total dissolution with hydrochloric acid (HCl) which aims to dissolve all elements in the precipitate and precipitation with ammonium hydroxide (NH4OH) which aims to separate radioactive elements and rare earth elements. Both methods were carried out under optimum process conditions with various variations in pH, temperature, and time. Based on observations, it was found that the optimum solubility of each element was 67.6% uranium, 15.3% thorium and 50.8% LTJ under the dissolving process conditions of pH 1, at 80°C for 2 hours. While in the deposition process, the precipitation recovery of each element is 57% uranium, 75.7% thorium, 4.8% rare earth metals at pH 6 conditions. Based on these data, it can be concluded that uranium, thorium, and rare earth elements can be dissolved at pH 1, at 80°C for 2 hours, and can be separated at pH 6 precipitation conditions.

Infrared absorption spectra of formates of the rare earth elements

1967 ◽  
Vol 8 (1) ◽  
pp. 45-49 ◽  
Author(s):  
O. D. Saralidze ◽  
L. P. Shklover ◽  
K. I. Petrov ◽  
V. E. Plyushchev
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Infrared Absorption Spectra ◽  
The Rare Earth

The Influence of Sample Self-Absorption on Wavelength Shifts and Shape Changes in the Soft X-Ray Region: The Rare-Earth M Series

1967 ◽  
Vol 11 ◽  
pp. 230-240
Author(s):  
David W. Fischer ◽  
William L. Baun
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Absorption Spectra ◽  
Emission Spectra ◽  
Emission Lines ◽  
Electron Transitions ◽  
Emission And Absorption Spectra ◽  
Real Emission ◽  
Shape Changes ◽  
The Rare Earth

AbstractThe Mα and Mβ emission spectra and the Mjv and My absorption spectra have been studied for the entire series of rare-earth elements. It is conclusively shown that the complicated multiplet structure observed in the emission spectra is not real emission structure but is, instead, produced by sample self-absorption. This is demonstrated by observing the emission spectra over wide variations in take-off angle and bombarding electron energies and finally by comparing the detailed structure of both the emission and absorption spectra. The MIV and MV absorption structure completely overlaps the Mα and Mβ emission lines, which are each found to have but one intensity maximum when obtained under conditions of minimum. self-absorption. Some of these spectra have never been shown previously, while others have been studied in detail by several investigators. Points of agreement and disagreement with previous work are mentioned, and the wavelengths of the emission lines and absorption edges are listed for all of the rare-earth elements. It is concluded that the 4f → 3d electron transitions are reversible in these elements.

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