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    Wyświetlanie 1-7 z 7
    Tytuł:
    Leaching kinetic study of Y and Eu from waste phosphors using hydrochloric acid solution containing hydrogen peroxide
    Autorzy:
    Yu, M.
    Jiang, Z.
    Mei, G.
    Chen, X.
    Powiązania:
    https://bibliotekanauki.pl/articles/949690.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    waste phosphors
    leaching
    kinetics
    rare earth elements
    Opis:
    The leaching kinetics of Y and Eu from waste phosphors using a hydrochloric acid (HCl) solution containing hydrogen peroxide (H2O2) were investigated. Characterization of the waste phosphors was performed using XRD to ascertain the phases as (Y0.95Eu0.05)2O3 (red phosphors), (Ce0.67Tb0.33)MgAl11O19 (green phosphors), (Ba0.9Eu0.1)Mg2Al16O27 (blue phosphors), and SiO2 (quartz). The influence of factors such as HCl concentration, addition amount of H2O2, temperature, and reaction time on the leaching performance of Y and Eu was investigated. The maximum leaching recoveries of Y (99.87%) and Eu (88.72%) were obtained at 4 M HCl, 0.2 cm3/g H2O2, 60 ℃ temperature, and 180 min of reaction time at a liquid-to-solid ratio of 7.5 cm3/g. Leaching kinetic results showed the best fit with the shrinking sphere model (1-(1-x)1/3)=kct), ensuring that the overall leaching process was governed by a chemical control mechanism. Activation energies of 42.35 and 33.28 kJ/mol were acquired for leaching of Y and Eu, respectively, at 40-70 ℃, which further supports the proposed chemical control leaching process.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 238-248
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Solubility of Eskisehir thorium/rare earth ores in sulphuric and nitric acids
    Autorzy:
    Kursun, I.
    Tombal, T. D.
    Terzi, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/109924.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    thorium
    rare earth elements
    bastnaesite
    leaching
    solubility
    Opis:
    Nuclear energy is considered as one of the most important energy resources in the world. Thorium (Th) has a significant potential to be used in electricity production by nuclear energy since its existence is not depended on the presence of another radioactive elements, and it has larger potential reserves than uranium. Bastnaesite ((Ce, La)CO3F) is one of the minerals from which Th can be economically extracted. In this study, solubility of bastnaesite containing ore obtained from Eskisehir, Turkey was investigated by leaching with H2SO4 and HNO3 in terms of leaching performance of thorium and some rare-earth elements (Ce, Nd, La). In this context, representative samples were taken from three different areas in Eskisehir-Kizilcaoren region, and a composite sample was prepared to be used for the leaching experiments. The effects of several parameters such as the solid ratio, leaching time, acid amount and pulp temperature, on dissolution efficiencies of Th, Nd, Ce and La was investigated. The best results were obtained using 3.42 mol/dm3 HNO3, solid–to–liquid ratio of 35%, 120 min leaching time and 60 oC temperature. Under these optimum conditions, the dissolution efficiencies of Th, Ce, Nd, and La were obtained as 94%, 82%, 77% and 70%, respectively.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 476-483
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The recycling-oriented material characterization of hard disk drives with special emphasis on NdFeB magnets
    Autorzy:
    Dańczak, A.
    Chojnacka, I.
    Matuska, S.
    Marcola, K.
    Leśniewicz, A.
    Wełna, M.
    Żak, A.
    Adamski, Z.
    Rycerz, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/109315.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    hard disk drives
    rare earth elements
    permanent magnets
    recycling
    Opis:
    Hard disk drives (HDDs) consist of many components made from various materials: e.g. aluminum, steel, copper and rare earth elements (REEs). Recycling and reuse of these materials is desirable for economic and environmental reasons. Developing of potential HDDs recycling methods requires knowledge about HDDs material characteristic. The study aims to explore knowledge about structure and chemical composition of HDDs main components with special emphasis on NdFeB magnets. HDDs collected for the experiments came from Desktop PCs and Notebooks. The dependence between the average mass of HDDs components and such parameters as producer, year and country of production and disk capacity was analyzed. Chemical composition of NdFeB magnets and the heaviest components (i.e. top cover, mounting chassis, platters and metallic plates from magnet assembly of actuator) was analyzed by various analytical methods. The heaviest HDDs main components: top cover and mounting chassis, with the highest recycling potential, are made of aluminum and steel respectively. The majority of HDDs components showed also the existence of different alloy additions: C, Mg, Si, P, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sn and Pb. NdFeB magnets constitute 2.2 ± 1.1% of the average HDD from Desktop PC (517.3 ± 64.2 g) and 3.2 ± 1.2% from Notebook (108.2 ± 24.3 g). The chemical composition of NdFeB magnets from collected HDDs changes in the wide range: Fe (53–62%), Nd (25–29%), Pr (2–13%), Dy (0.1– 1.4%), Ni (2–6%), Co (0.5–3.6%), B (0.8–1.0%). Recycling of permanent magnets based on NdFeB alloys is potential remedy to fill the gap in the supply of rare earth elements on the global REEs market.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 363-376
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of alkali processing for the recycling of rare earth values from spent fluorescent lamps
    Autorzy:
    Shukla, Neha
    Tanvar, Himanshu
    Dhawan, Nikhil
    Powiązania:
    https://bibliotekanauki.pl/articles/1449193.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    fluorescent lamps
    rare earth elements
    activation energy
    recovery
    cerium
    terbium
    Opis:
    Phosphor samples collected after crushing and sieving of discarded fluorescent lamps comprise approximately 31 % rare earth elements in the form of $Y_{1.90}Eu_{0.10}O_3$, $Al11Ce_{0.67}MgO_{19}Tb_{0.33}$, and $Al_{10.09}Ba_{0.96}Mg_{0.91}O_{17}$: $Eu^{2+}$ phase. Direct leaching and mechanical activation assisted leaching are incapable of recovering $Ce$, $Tb$ values from the $Al_{11}Ce_{0.67}MgO_{19}Tb_{0.33}$ phase. Heat treatment with $NaOH$ was found successful for dissociation of $Ce$, $Tb$ phase via substitution of rare-earth ion by $Na^+$ ion to form rare earth oxide and water-soluble $NaAlO_2$. $Y$, $Eu$, $Ce$, and $Tb$ values were recovered from heattreated mass in a two-step leaching process followed by recovery from the leach solution by oxalic acid precipitation. Over 95 % extraction rate was attained after heat treatment at 400 °C with 150 wt-% $NaOH$ for 1 h. It was found that $Y$, $Eu$ containing phase does not take part in the heat treatment process whereas the $Ce$, $Tb$ phase undergoes a solid-state chemical reaction with $NaOH$ via product layer diffusion model with 41.5 kJ/mol activation energy. Approximately 15 g mixed oxide (purity >95 %) of $Y$ (79 %), $Eu$ (7 %), $Ce$ (5 %), and $Tb$ (4 %) could be recovered from 100 units of discarded FLs. Microwave treatment of phosphor and $NaOH$ (50 wt-%) yielded approximately 42 % $Y$, 100 % $Eu$, 65 % $Ce$, and 70 % Tb recovery in just 5 min. Approximately 9 g of REO and 5 g of cerium enriched leach residue were recovered from the microwave route within 5 min and depicted high microwave potential application in the recovery of $Ce$ and $Tb$ values from waste phosphor sample.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 4; 710-722
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Separation of rare earth elements from the leaching solution of waste phosphors by solvent extraction with Cyanex 272 and its mixture with Alamine 336
    Autorzy:
    Xing, Weidong
    Lee, Man Seung
    Powiązania:
    https://bibliotekanauki.pl/articles/1449503.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    phosphors
    rare earth elements
    HCl solution
    solvent extraction
    Cyanex 272
    Opis:
    Waste phosphors contain rare earth elements (REEs) such as yttrium (Y), europium (Eu), cerium (Ce), terbium (Tb) and lanthanum (La). Separation of these REEs from the leaching solution of waste phosphors was investigated by solvent extraction with single Cyanex 272, binary mixture (mixture of Cyanex 272 and Alamine 336), ionic liquid (prepared by Cyanex 272 and Aliquat 336) in kerosene. The effect of solution pH and extractants concentration was mainly investigated. The results indicated that Y(III) was selectively extracted by single Cyanex 272 over the other four REEs from the HCl solution with initial pH range from 3 to 5. Synergistic extraction with the binary mixture was enough for the extraction of Y(III), Tb(III) and Eu(III) with a small amount of Ce(III). Scrubbing with pure Y(III) solution with intermediate acidity was effective in scrubbing Ce(III) from the loaded binary mixture organic phase. Stripping behavior of the Y(III), Tb(III) and Eu(III) by HCl solution was similar to each other. Tb(III) and Eu(III) can be separated by extraction with the binary mixture followed by scrubbing with pure Tb(III) solution. McCabe-Thiele diagrams were constructed for the extraction of Y(III) by single Cyanex 272 and that of Tb(III) by the mixture. A process was proposed for the separation of REEs from the leaching solution of waste phosphors by solvent extraction.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 1; 184-194
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on REE occurrence in a Svanbergite and basic ore characteristics
    Autorzy:
    Ma, Keyu
    Zhang, Jie
    Deng, Qiufeng
    Men, Pengpeng
    Zhang, Yusong
    Shi, Xiulin
    Powiązania:
    https://bibliotekanauki.pl/articles/2146882.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    svanbergite
    rare earth elements (REEs)
    occurrence state
    crandallite
    ore characteristics
    Opis:
    Svanbergite in Sichuan Province, China is a special middle-low grade phosphorus ore. It contains rare earth elements (REEs), aluminum, and strontium that can be exploited and utilized. In this study, several methods were used to systematically study the occurrence of REEs in the ore and basic ore characteristics. The ore, which was rich in REEs, Al, and Sr, was classified as marine sedimentary low-grade phosphorus ore. The main ore mineral was crandallite and pyrite, and independent REE minerals were not found. Crandallite was the main carrier mineral of useful elements, including P, REEs, Al, and Sr. REE+ was inferred to mainly exist in crandallite via isomorphism by replacing Ca2+ and H+. The crandallite was mainly characterized as fine-grained, and minerals were closely disseminated. The results from this study will provide a valuable reference for expanding available REE resources and the efficient comprehensive utilization of svanbergite.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 3; art. no. 147377
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    High-temperature carbothermal dephosphorization of Malaysian monazite
    Autorzy:
    Udayakumar, Sanjith
    Sheikh Abdul Hamid, Sheikh Abdul Rezan
    Baharun, Norlia
    Pownceby, Mark
    Powiązania:
    https://bibliotekanauki.pl/articles/2146886.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    malaysian monazite concentrate
    dephosphorization
    carbothermal reduction
    rare earth elements
    graphite
    Opis:
    High-temperature carbothermal reduction experiments with graphite powder were conducted to assess the dephosphorization behavior of Malaysian monazite concentrate. Thermodynamic analysis of the possible dephosphorization reactions was conducted to evaluate the feasibility of the carbothermal reduction of the monazite phases. The effects of temperature, particle size, and monazite to carbon ratio were then investigated under different conditions. The carbothermal reduction experiments were conducted based on the Taguchi design method, and up to 97% of phosphorous removal was achieved under optimized conditions. The optimal conditions for dephosphorization were determined as; a reduction temperature of 1350 °C, a particle size of -75 μm, and monazite to carbon molar ratio of 0.3. Microstructural and phase characterization of the dephosphorized products revealed that CeO2, Nd2O3, La2O3, and Pr2O3 oxide phases were prominent, and no residual peaks of monazite remained in the reduced products. The information gained from the study can aid in the design of a suitable post-dephosphorization hydrometallurgical treatment for exploiting Malaysian monazite as a local source of REEs.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2021, 57, 6; 140--155
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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