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An Overview of Rare Earth Ores Beneficiation in Vietnam

Nhu Thi Kim Dung, Pham Van Luan, Vu Thi Chinh, Tran Van Duoc

Inżynieria Mineralna

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2021

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no. 2

227--236

EN

Rare earth metals are used in electricity, electronics, nuclear, optics, space, metallurgy, superconducting and super magnetic materials, glass and ceramics, and agriculture. Some rare earth elements are added to fertilizers for crops and some trials for animal feed. Rare earth elements, except for radioactive promethium, are relatively abundant in the earth's crust. Vietnam has a tremendous rare earth potential, distributed mainly in the Northwest, including Nam Xe, Dong Pao, Muong Hum, and Yen Bai. There are many research projects on rare earth ores of different types globally, but the focus is mainly on the essential minerals, including monazite, xenotime, and bastnaesite. This report summarizes research data on rare earth ore intending to produce a general assessment of rare earth ore and its beneficiation technology in Vietnam.

2

Metale ziem rzadkich : otrzymywanie i odzysk z materiałów odpadowych

Saternus M., Willner J., Fornalczyk A., Lisińska M.

Przemysł Chemiczny

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2017

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T. 96, nr 7

1595--1599

PL

Metale ziem rzadkich zyskują coraz większe znaczenie we współczesnym świecie. Stosowane są do produkcji magnesów, laserów, szkła, luminoforów. Lampy LED, komputery czy telewizory to urządzenia, które bez tych metali nie mogłyby istnieć. Przedstawiono podstawowe zastosowanie metali ziem rzadkich. Podano ceny ich tlenków w latach 1995-2016 oraz wielkość ich produkcji. Przedstawiono metody produkcji tych metali z rud oraz ich alternatywne otrzymywanie poprzez recykling materiałów odpadowych, takich jak magnesy, fosfory czy akumulatory NiMH. W podsumowaniu podano prognozę zużycia metali ziem rzadkich.

EN

A review with 55 refs.

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Conventional synthesis and characterization of rare earth doped barium borophosphates, BaBPO5:RE (Y, Gd and La)

Çelik Gül G., Kurtuluş F.

Archives of Materials Science and Engineering

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2016

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Vol. 81, nr 2

49--54

EN

Purpose: of this research, our target is synthesis and characterization of rare earth metals such as Y, Gd and La doped barium borophosphate compounds which are applicable in non-linear optics industry. Design/methodology/approach: The starting materials rare earth oxides, barium carbonate, boric acid and ammonium dihydrogen phosphate as analytically grade weighed 0.01:1:1:1 molar ratio and homogenized in an agate mortar. The mixture placed into a porcelain crucible to heat in high temperature oven step by step. First, mixtures were waited at 400°C for 2 hours for calcination process, subsequently heated 900°C with step rate 10°C/m for 8 hours, and finally cooled down to room temperature with step rate 10°C/m. After many grindings final product get ready for characterization. X-ray powder diffraction (XRD) analysis was performed using PANanalytical X’Pert PRO Diffractometer (XRD) with Cu Kα (1.5406 Å, 45 kV and 30 mA) radiation. Fourier transform infrared spectroscopy (FTIR) was taken on a Perkin Elmer Spectrum 100 FTIR Spectrometer from 4000 to 650 cm-1. Scanning electron microscopy was achieved in SEM JEOL 6390-LV. Luminescence properties were performed by Andor Solis Sr 500i spectrophotometer. Conventional solid state syntheses were done in Protherm furnace. Findings: The powder XRD patterns of the samples show that there is no impurity related to doping materials mean all diffractions corresponding to host material barium borophosphate crystallized in hexagonal system with unit cell parameters a=7.1003 and c=6.9705 Å. The unit cell parameters of rare earth doped barium borophosphates were calculated and display both increase and decrease depends on ionic Radius of rare earths. The other supporting methods confirm the crystal structure and luminescence properties. Research limitations/implications: The synthesis method has some disadvantages such as low homogeneity, non-uniform product etc. We tried to minimize these negative aspects in our research and succeeded. Practical implications: Phosphor materials Y:BaBPO5, Gd:BaBPO5 and La:BaBPO5 (ICSD 51171) were synthesized by conventional solid state method and characterizations was mainly based on powder X-ray diffraction pattern. Also, morphological and luminescence properties were completed to get the highest knowledge. Originality/value: Of the paper is first time conventional synthesis of Y, Gd and La doped BaBPO5 compounds, calculation of unit cell parameters, and investigation of morphological and luminescent properties.

4

Wzrost monokryształów molibdenianu wapnia domieszkowanych jonami ziem rzadkich (CaMoO4 : RE) do badań w zakresie immobilizacji odpadów radioaktywnych

Świrkowicz M., Szyrski W., Kisielewski J., Wieteska K., Wierzchowski W., Malinowska A., Wierzbicka E., Karaś A., Jurkiewicz-Wegner E.

Materiały Elektroniczne

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2013

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T. 41, nr 4

10--19

PL

Stosując metodę Czochralskiego oraz układ cieplny z tyglem platynowym o średnicy 55 mm i wysokości 55 mm oraz biernym dogrzewaczem platynowym uzyskano monokryształy CaMoO4 niedomieszkowane i domieszkowane europem, neodymem oraz jednocześnie europem i neodymem o średnicy do 25 mm i długości do 90 mm. Szybkość wzrostu zawarta była w zakresie 1,5 - 3,0 mm/h, a szybkość obrotowa 10 - 15 obr./min. Pierwsze procesy wzrostu przeprowadzono stosując niezorientowane zarodki z CaWO4 (National Institute of Standards and Technology, USA). W oparciu o otrzymane monokryształy przygotowano zarodki o orientacji [001]. Przeprowadzono badania dyfrakcyjne rentgenowskie, synchrotronowe topograficzne, właściwości optycznych i składu chemicznego. Określono współczynniki segregacji europu i neodymu (kEu ≈ 0,40, kNd ≈ 0,28). Stwierdzono, że w przypadku współdomieszkowania rośnie współczynnik segregacji neodymu a maleje europu (kEu ≈ 0,30 i kNd ≈ 0,32). Transmisja optyczna monokryształów silnie zależy od domieszki. W przypadku neodymu obserwuje się wyraźne i ostre pasma absorpcji. Monokryształy z europem wykazują silną absorpcję w zakresie widzialnym i bliskiej podczerwieni.

EN

Single crystals of CaMoO4 either undoped or doped with europium, neodymium and europium and at the same time with neodymium with a diameter of 25 mm and a length of up to 90 mm, were obtained using the Czochralski method and a thermal system with a platinum crucible 55 mm in diameter and 55 mm in height and a passive platinum afterheater. The growth rate was in the 1.5 - 3.0 mm/h range and the rotation rate varied between 10 and 15 r./min. At the beginning, the growth processes were carried out applying un-oriented CaWO4 seeds (from the National Institute of Standards and Technology, USA). Based on the resultant single crystals, [001] - oriented seeds were prepared. X-ray powder diffraction patterns, synchrotron topography, optical transmission and chemical compositions were measured. Segregation coefficients of europium and neodymium were determined to be kEu ≈ 0,40 and kNd ≈ 0,28 respectively. In the case of co-doping, the segregation coefficient of neodymium increases and that of europium decreases (kEu ≈ 0,30 and kNd ≈ 0,32). The optical transmission of single crystals strongly depends on the dopant. Sharp and narrow absorption bands are observed for neodymium, whereas single crystals with europium exhibit a strong absorption in the visible and near-infrared regions.

5

Non-metallic inclusions in high manganese austenitic alloys

Grajcar A., Galisz U., Bulkowski L.

Archives of Materials Science and Engineering

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2011

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Vol. 50, nr 1

21-30

EN

Purpose: The aim of the paper is to identify the type, fraction and chemical composition of non-metallic inclusions modified by rare-earth elements in an advanced group of high-manganese austenitic C-Mn-Si-Al-type steels with Nb and Ti microadditions. Design/methodology/approach: The heats of 3 high-Mn steels of a various content of Si, Al and Ti were melted in a vacuum induction furnace and a modification of non-metallic inclusions was carried out by the mischmetal in the amount of 0.87 g or 1.74 g per 1 kg of steel. Evaluation of the metallurgical purity of steels with non-metallic inclusions was done basing on determination their fraction, type, size and morphology. Stereological parameters of the inclusions were assessed by the use of automatic image analyzer cooperating with light microscope. EDS method was used to assess the chemical composition of non-metallic inclusions. Findings: It was found that the steels are characterized by high metallurgical purity connected to low concentrations of phosphorus and gases at a slightly higher sulphur content, introduced to a melt together with electrolytic manganese. The steels contain fine sulfide inclusions with a mean size from 21 to 25 ěm2 in a majority and their fraction equals from 0.047 to 0.09%, depending on sulphur content. MnS, carbonitrides of the (Ti,Nb)(C,N) type and complex carbosulfides containing Mn, Ti and Nb were identified in steels. The beneficial influence in decreasing a fraction of non-metallic inclusions and their susceptibility to elongate in a rolling direction has a higher addition of mischmetal and titanium microaddition. A modification of the chemical composition of non-metallic inclusions by Ce, La and Nd proceeds in an external zone of inclusions. Research limitations/implications: Further investigations relating the type and morphology of non-metallic inclusions to mechanical properties of sheets at various sections according to the rolling direction are needed. Practical implications: The knowledge of the type and morphology of non-metallic inclusions forming in high-Mn alloys and the effectiveness of their modification has a significant meaning for metallurgical and steel making technologies. Originality/value: A problem of the identification of non-metallic inclusions modified by REE and titanium is a new topic in studies on the metallurgical purity of advanced high-strength high-manganese steels.

6

Barwienie szkła pierwiastkami ziem rzadkich na przykładzie prazeodymu

Środa M., Cholewa-Kowalska K.

Materiały Ceramiczne

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2009

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T. 61, nr 3

208-211

PL

Ziemie rzadkie jako domieszki optycznie aktywne znajdują coraz szersze zastosowanie w szkłach dla optoelektroniki. Energia przejść elektronowych typu f-f w lantanowcach odpowiada zakresowi fal od bliskiej podczerwieni do bliskiego ultrafioletu, co ma bezpośredni wpływ na barwę szkła. W pracy przeprowadzono badania transmisji w zakresie UV-VIS dla szkieł, których matryce oparte były na różnych tlenkach więźbotwórczych (SiO2, P2O5, B2O3, PbO). Stwierdzono, że matryca szkła nie wpływa na położenie pasm absorpcyjnych prazeodymu, natomiast wpływa na intensywność pasm przy 470 nm i 483 nm, które zmazane są z przejściami do poziomów 3P, i 3P0. Wyznaczając parametry barwy w układzie CIE L*a*b* pokazano, że zdolność barwiąca jonów prazeodymu jest zależna od typu szkła.

EN

Rare earth elements are widely used as active optical dopants to luminescent and photonic materials. Energy transition between f-f orbitals of rare-earth elements gives effects in the visible region of spectrum. It induces the change of colour of the glass. The effect of a glassy matrix (SiO2, P2O5, B2O3, PbO) on the colouration properties of Pr3+ has been studied. It was stated that the matrix does not influence the position of absorption bands. However, it affects the intensity of bands at 470 nm and 483 nm, which are connected with electron transfers to the 3P, and 3P0 states, respectively. Basing on the L*a*b CIE system, it was shown that the colouration ability of Pr3+ depends on the type of glass.

7

Effect of lanthanum on the tensile properties of carbon-fibre reinforced thermoplastic polyimide composites

Li J., Cheng X. H.

Materials Science Poland

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2007

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Vol. 25, No. 1

85--93

EN

Rare earth (RE) La modification and air-oxidation methods were used to improve the interfacial adhesion of the carbon fibre reinforced polyimide (CF/PI) composite. The interfacial characteristics of composites reinforced by carbon fibres, treated with different surface modification methods, were investigated comparatively. Results showed that both RE modification and air-oxidation method improved the adhesion between the reinforcement and matrix, and that the RE modification method was superior to the air-oxidation method. For the CF/PI composite, optimum interfacial adhesion was obtained at 0.3 wt. % of La concentration. The fracture surfaces of samples were investigated by scanning electronic microscopy (SEM) to analyse the effects of various surface treatment methods.

8

Preparation and upconversion properties of Er3+,Yb3+:Y2Si2O7 nanocrystallites embedded in PVA polymer nanocomposites

Hreniak D., Głuchowski P., Stręk W., Bettinelli M., Kozłowska A., Kozłowski M.

Materials Science Poland

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2006

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Vol. 24, No. 2/1

405--413

EN

The preparation of polymer nanocomposites consisting of poly(vinyl) alcohol (PVA) network and RE3+:Y2Si2O7 nanocrystalline particles (RE=Yb, Er) is presented. The optical properties of the nanocomposite were preliminarily studied. In particular, efficient upconversion was observed in Er3+ and Yb3+ codoped Y2Si2O7 nanoparticles embedded in the polymeric PVA host. It was found that the luminescence features of the RE3+:Y2Si2O7 nanoparticles were affected by the polymeric host, resulting in a shortening of the luminescence lifetimes. This effect is discussed in terms of effective refractive index.

9

Magnetic properties and electronic structure of YxGd1-xNi5 compounds

Bajorek A., Stysiak D., Chełkowska G., Deniszczyk J., Borgieł W., Neumann M.

Materials Science Poland

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2006

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Vol. 24, No. 3

867--874

EN

Measurements of the magnetic susceptibility, crystal and electronic structure for YxGd1-xNi5 (x=0.0, 0.2, 0.5, 0.8, 1.0) compounds with the CaCu5 type of crystal structure are reported. The substitution of Y for Gd atoms results in a decrease of the volume unit cell and the Curie temperature. In the paramagnetic range (300-650K) the DC susceptibility follows Curie-Weiss law for all investigated compounds. The effective moment deduced from the Curie constant decreases rapidly with Y concentration. The saturation magnetic moment for GdNi5 shows negative polarization of Ni 3d band induced by interactions with Gd 5d states. Both valence band and core level X-ray photoelectron spectra are analyzed. The presence of the satellite structure in Ni2p core level suggests the magnetic polarisation of Ni 3d states which dominate the valence band in all investigated compositions. The experimental investigations were completed with the band structure calculations. In all cases the calculations were based on KKR and KKR-CPA methods. Satisfactory agreement between the measured spectra and those obtained from the calculated electronic structure has been achieved.

10

Wysokotemperaturowe materiały nadprzewodnikowe

Sosnowski J.

Przegląd Elektrotechniczny

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2003

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R. 79, nr 9(2)

623-625

PL

W pracy zaprezentowano postępy w odkrywaniu nowych materiałów nadprzewodnikowych oraz rolę płaszczyzn miedziowo-tlenowych w osiąganiu coraz większych wartości temperatury krytycznej. Opisano również występowanie nadprzewodnictwa wysokotemperaturowego w materiałach nie będących związkami miedzi, takich jak fullereny oraz nowoodkryty nadprzewodnik dwuborek magnezu. Przedstawiono modele teoretyczne uwzględniające warstwową strukturę krystalograficzną nadprzewodników wysokotemperaturowych.

EN

In the paper, progress in the enhancement of the critical temperature of the superconducting materials has been presented. The influence of the copper-oxide planes on the critical temperature has been shown. The occurrence of high temperature superconductivity in the non-copper compounds, such as fullerenes and magnesium diboride, has also been investigated.