Extractive metallurgy of rare earths

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He is an alumnus of Banaras Hindu University. Gupta has authored nearly publications. New Edition Now Covers Recycling, Environmental Issues, and Analytical Determination Employing four decades of experience in the rare metal and rare earths industry, the authors of Extractive Metallurgy of Rare Earths, Second Edition present the entire subject of rare earth elements with depth and accuracy. This second edition updates the most important developments from the past 10 years. It emphasizes advances made in rare-earth materials processing converting a rare-earth metal, alloy, or compound to a device-ready material , breakthroughs in the area of rare-earth separation, and now includes a chapter on the recycling of rare earth elements from magnets, batteries, and phosphors among others, covering both manufacturing scrap or materials in end of life devices.

Extraction of rare earths from iron-rich rare earth deposits

Essential to Your Collection This second edition presents comprehensive, detailed, and up-to-date coverage that includes: All aspects of rare earth extractive metallurgy A status of rare earth extraction from various world resources Flow sheets that can be used for rare earths separation, metal reduction, alloy making, refining and end product materials preparation Techniques of various rare earths recycling options An outline of environmental issues in rare earths mining and processing Methods of rare earths determination and analyses of components and impurities in rare earth materials Information extensively linked to primary literature with a complete listing of references A narration of the changing scenario of world rare earth resources and possibility of their exploitation An indispensable resource, Extractive Metallurgy of Rare Earths, Second Edition explains the many aspects of rare earth extractive metallurgy clearly and systematically.

The text reveals process implementation possibilities and research opportunities, and considers potential solutions to the challenges impacting this rapidly changing industry. Read more Read less. Amazon Global Store US International products have separate terms, are sold from abroad and may differ from local products, including fit, age ratings, and language of product, labeling or instructions.

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English Choose a language for shopping. The use of organophosphorous extractants Thakur, and phosphine oxide Shaibu et al. Recent research on rare earth solvent extraction has been done in Brazil. Morais and Ciminelli report a process to obtain a high-grade La 2 O 3 with a yield of In the year , a hydrometallurgical demonstration of a leaching and solvent extraction plant unit, which produced rare earth compounds, was operated by the Nuclear Industries of Brazil — INB in Minas Gerais state MG and was closed after a period of experimental operation Rosental, The Centre for Mineral Technology - CETEM, in Rio de Janeiro RJ , worked in the 80s in the design and implementation of a pilot plant for solvent extraction to separate the rare earths, yielding high purity oxides of samarium, neodymium and gadolinium from leach liquors originating from monazite ore Barbosa, In Brazil, the processing of rare earths, and the production of compounds, metals or alloys partially developed in the past, needs to be renewed, updated and expanded to include new sources and new technologies minerals.

As a target of the Brazilian government, the Ministry of Science, Technology and Innovation - MCTI is currently promoting initiatives for the resumption of research on rare earths in Brazil. Thus, the present study shows results of research conducted by the Centre for Mineral Technology - CETEM aiming at contributing to the structuring and development of a rare earth supply chain, considered as promising and strategic for Brazil.

A synthetic liquor of rare earths was produced with a rare earth composition similar to an actual liquor corresponding to the leaching stage of a Brazilian monazite. Beyond batch laboratory tests for investigation of process variables, a micro continuous pilot plant was operated for monitoring of performance at each stage of extraction. The tests had as their main objective to verify the best conditions for the separation of LREE from other rare earth elements in a synthetic liquor.

The quantitative analysis was performed for the elements La, Pr, Nd and Sm. Sm was used as a reference for the separation between light and heavy elements. In the case of the pilot plant, Gd was also analyzed. The synthetic liquor of rare earth chlorides was prepared from their oxides with added in stoichiometric excess HCl and heated. Before the addition of HCl, a paste was made with the mixture of oxides and distilled water in a beaker to facilitate the solubility of the same.

After the preparation of this paste, the beaker was heated on a hot plate and HCl was added slowly. The rare earth elements are completely solubilized when the solution becomes clear. After this process, the beaker should be heated to reduce the initial volume and form a wet and compact paste. The final mixture should then be transferred to a flask and the final volume completed with distilled water. All the rare earth compounds were supplied by Nuclear Industries of Brazil S. The absence of cerium in the synthetic liquor was designed to simulate a liquor from which cerium had been previously removed by precipitation.

The extraction system was composed of organic solutions of DEHPA Di- 2-ethylhexyl phosphoric acid , in different concentrations. Concentrations of rare earth in the aqueous phases were determined by optical emission spectrometry with inductively coupled plasma — ICP-OES Agilent , and the concentrations of the organic phase were determined by mass balance. The tests were performed varying the initial pH of the liquor to investigate the influence in the percentages of extraction and separation factor.

The pH of the liquor was initially set to a value determined in each test with addition of HCl 6. The extraction tests were performed in Erlenmeyer flasks under agitation of rpm in a reciprocal shaker IKA , 15 minutes and at room temperature. After this time the solution was put at rest for 40 minutes in a separation funnel for the separation phase.

The tests followed the same methodology described in section 2. The time influence between 15 and seconds on the percentage of extraction was studied. In all tests, the pH was maintained at 1. A volume of 50mL of aqueous and organic solutions wasused. The tests were also conducted in a beaker with magnetic stirring. These tests were performed to construct the McCabe-Thiele diagram for determining the number of stages required in a circuit of extraction for the separation of heavy rare earths from other lighter elements.

Seven tests were performed at three different pH values 0. The tests were conducted following the same methodology of the other previous tests. The continuous counter-current experiments were carried out in a sequence of mixer-settler stages, with mixers of mL and settlers of mL. Six stages for extraction were used as shown in Figure 1. The DEHPA Di- 2-ethylhexyl phosphoric acid is a kind of typical organic phosphoric acid extractant, widely used for rare earth separation because of its higher extraction efficiency.

This reagent is a liquid cationic extractant and the metal is exchanged by the hydrogen ion of its hydroxyl group. In general, on industrial solvent extraction application concentrations, the DEHPA form dimmers in kerosene solutions Hirashima, et al. Figure 2 shows the performance of extraction of light elements and samarium by DEHPA as a function of initial aqueous phase pH. The extraction efficiency at an equal volume of organic and aqueous phases is commonly defined by:. As expected, the extraction increases with increasing aqueous pH.

It was observed that at pH 1. The preference for the DEHPA extraction of rare earth elements increases with increasing atomic number. The distribution ratio D was calculated as the ratio of the concentration of metal present in the organic phase [M] org to that in the aqueous phase [M] aq at equilibrium:. It is of considerable interest to quantitatively compare the separation ability.

The values of the separation factors for the pair of elements Sm-Nd are represented in Figure 3. The separation factor values calculated confirm the optimum pH value to be between 0. It is believed that the observed fact relates to the formation of complex species extracted. It is known that acid extractants of a chelating nature or monobasic such as DEHPA release a hydrogen from each molecule that combines with the metal extracted. The number of molecules of extractant involved in the formation species extracted depends, among other things, onthe oxidation state or the coordination number of the metal ion in solution.

Thus the volume occupied by these species in the organic phase can be a limiter to promote extraction. The different times of extraction evaluated in this test, and the percentage of extraction are shown in Figure 5. The chemical equilibrium of extraction is reached very quickly with no significant difference in the percentage of extraction after 30 seconds. In subsequent experiments, a contact time of 15 minutes is adopted to ensure complete equilibration.

The isotherms were plotted in the three pH values, 0.

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However, only the McCabe-Thiele isotherm at 1. In Figure 7 , notice that the isotherm at pH 1.

Dr Dreisinger on extraction technologies for Rare Earths

For example, with feed liquor at around 1. The first point of the curve, in reality is not an experimental point but rather a continuation of the trend line in order to mark the beginning of the operating line.

Extractive Metallurgy of Rare Earths

It should also be noted that the curve is shifted to the right, meaning that case one still likely have residue of Sm in the raffinate. Figure 8 shows the results of average extraction by stage, for the elements La, Pr, Nd, Sm and Gd for two days of operation. We highlight the good extractions Sm and Gd in the first stage, while the other metals, the light ones, feature extraction increased over the subsequent stages. With these observations, we note that the separation factor between the medium and light REE will decrease along the circuit. This paper presents results for the analysis of technical indexes for separating light REE from the medium and heavy REE, in hydrochloric media, by solvent extraction.

The extraction increases with increasing aqueous pH, particularly for Sm.

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The separation factor calculated confirm the optimum pH value between 0. The result of the continuous circuit presents similarities with the information showing the possibility of separation for these elements.

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  • Mineral Summary. Accessed on: 31January Progress Report. Solvent extraction separation of La from chloride solution containing Pr and Nd with Cyanex Hydrometallurgy , v. Solvent extraction separation of Pr and Nd from chloride solution containing La using Cyanex and its mixture with other extractants. Separation and Purification Technology , v.

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