The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

Koen Binnemans - One of the best experts on this subject based on the ideXlab platform.

  • recovery of rare earths from waste cathode ray tube crt Phosphor Powder by selective sulfation roasting and water leaching
    Hydrometallurgy, 2019
    Co-Authors: Mehmet Ali Recai Onal, Koen Binnemans
    Abstract:

    Abstract Until recently, most displays, such as television and computer screens, were based on cathode ray tubes (CRTs). With the introduction of new types of displays including liquid crystal displays, CRTs have been widely replaced, leading to a gradual build-up of hazardous CRT Powder waste. In this paper, a new approach is introduced where the valuable rare-earth elements (REEs) (i.e. yttrium and europium) in the Powder are selectively recovered, leaving behind a zinc-rich residue and glass for further recycling. The main rare-earth compound in the waste Powder is Y2O2S:Eu3+ (YOS). The fine-grained CRT Powder was mixed with zinc sulfate monohydrate (ZnSO4·H2O) and roasted at 600–900 °C for short periods of time. In this way, Y2O2S:Eu3+ was transformed into water-soluble rare-earth sulfates. Meanwhile, ZnS underwent a two-stage reaction with ZnSO4·H2O, where first a partially water-soluble intermediate (ZnO·2ZnSO4) and then the water-insoluble ZnO was formed. Addition of a sufficient amount of ZnSO4·H2O ensured the recovery of ≥95% of the rare earths in a subsequent water leaching step, but there was also co-dissolution of about 5% of the total amount of zinc present. Several purification methods were tested and compared to separate the REEs from the zinc impurity in the solutions. In addition to the conventional precipitation methods with sulfides and oxalic acid, a novel liquid-liquid exchange reaction between REE-containing leachate and zinc-loaded Versatic Acid 10 was tested. Finally, a complete flow sheet is proposed for the (almost complete) valorization of REEs as well as the total zinc present.

Zhe Tan - One of the best experts on this subject based on the ideXlab platform.

  • characterization recovery potentiality and evaluation on recycling major metals from waste cathode ray tube Phosphor Powder by using sulphuric acid leaching
    Journal of Cleaner Production, 2016
    Co-Authors: Xiangmiao Tian, Xiaofei Yin, Yu Gong, Zhe Tan
    Abstract:

    Abstract Phosphor Powder from waste cathode ray tubes (CRT) was leached by acid leaching technology, and also, “H2SO4 + H2O2” system was utilized to reduce the release of poisonous gas H2S into atmosphere, single-factor method was used to determine the optimal operation conditions (H2SO4 concentration, the volume of H2O2 and H2SO4, temperature, time and the ratio of liquid and solid). Moreover, a quantitative analysis on recovery benefits was conducted to evaluate the effect of this method. Our results demonstrated that the recovery of Y and Eu has highly positive profits, as their price reached 1018.69 CNY/kg and 380.64 CNY/kg, separately. However, the recovery of Zn and Al has negative profits was due to its lower enrichment factors (EFs) and market price in comparison with Y and Eu. In general, this technology has a great potential to recover four major metals from waste Phosphor Powder, about 757.04 CNY per kilogram Powder economic value can be produced using this process. Therefore, using “H2SO4 + H2O2” system for recycling Zn, Al, Y and Eu is a green and sustainable technology from waste cathode-ray tube fluorescent Powder.

Ingann Chen - One of the best experts on this subject based on the ideXlab platform.

  • copper concentration dependence of structure morphology and optical properties of zns cu cl Phosphor Powder
    Journal of Physics and Chemistry of Solids, 2008
    Co-Authors: Yung Tang Nien, Ingann Chen, Chii Shyang Hwang, Shengyuan Chu
    Abstract:

    Abstract ZnS:Cu,Cl Phosphors were prepared by firing ZnS Powder with 1 wt% NaCl and CuS nanocrystallites in the range of 40–5000 ppm at 900 °C for 2 h in an atmosphere of 3% H 2 /Ar and sulfur vapor. The particle size and structure of the ZnS:Cu,Cl Powders were found to depend on the Cu concentration. The Powders with Cu⩾400 ppm exhibited a cubic structure and were approximately 5 μm in size as compared to the hexagonal structure of those with less Cu additions (∼2 μm). The difference, resulting from the precipitation of Cu x S in the Powders as determined by X-ray photoelectron and diffuse reflectivity analyses, revealed that the Powders with Cu>400 ppm showed the Cu 2p main peaks and higher absorbance in the UV–vis region due to the wide range of the bandgap energy of Cu x S (1.2–1.75 eV). Electroluminescence (EL) consisting of blue, self-activated (SA) and green emission peaking at 440, 470 and 510 nm, was observed only in the Powders with Cu⩾400 ppm. Besides the activator concentration quenching effect, the variation of EL intensity with the Cu concentration was elucidated to result the from amount of Cu x S precipitates as well as charge carriers in the Powders.

  • raman scattering and electroluminescence of zns cu cl Phosphor Powder
    Applied Physics Letters, 2006
    Co-Authors: Yung Tang Nien, Ingann Chen
    Abstract:

    Raman spectra of ZnS:Cu,Cl Powders show a structural transition from hexagonal to cubic and a crystal growth with increasing Cu addition (>400ppm), which is supposed to result from Cu incorporation or CuxS precipitation. The redshift of longitudinal optical mode in ZnS:Cu,Cl with increased amounts of Cu suggests that the excess Cu ions were located interstitially in the lattice and created a tensile strain. Under an electric field (3.75×106V∕m), a broad emission spectrum superposing of green, self-activated blue, and blue bands can be observed in the Powders (Cu⩾400ppm), which agrees with the luminescence centers of CuZn+, vacancies, and Cui+, respectively.

Mehmet Ali Recai Onal - One of the best experts on this subject based on the ideXlab platform.

  • recovery of rare earths from waste cathode ray tube crt Phosphor Powder by selective sulfation roasting and water leaching
    Hydrometallurgy, 2019
    Co-Authors: Mehmet Ali Recai Onal, Koen Binnemans
    Abstract:

    Abstract Until recently, most displays, such as television and computer screens, were based on cathode ray tubes (CRTs). With the introduction of new types of displays including liquid crystal displays, CRTs have been widely replaced, leading to a gradual build-up of hazardous CRT Powder waste. In this paper, a new approach is introduced where the valuable rare-earth elements (REEs) (i.e. yttrium and europium) in the Powder are selectively recovered, leaving behind a zinc-rich residue and glass for further recycling. The main rare-earth compound in the waste Powder is Y2O2S:Eu3+ (YOS). The fine-grained CRT Powder was mixed with zinc sulfate monohydrate (ZnSO4·H2O) and roasted at 600–900 °C for short periods of time. In this way, Y2O2S:Eu3+ was transformed into water-soluble rare-earth sulfates. Meanwhile, ZnS underwent a two-stage reaction with ZnSO4·H2O, where first a partially water-soluble intermediate (ZnO·2ZnSO4) and then the water-insoluble ZnO was formed. Addition of a sufficient amount of ZnSO4·H2O ensured the recovery of ≥95% of the rare earths in a subsequent water leaching step, but there was also co-dissolution of about 5% of the total amount of zinc present. Several purification methods were tested and compared to separate the REEs from the zinc impurity in the solutions. In addition to the conventional precipitation methods with sulfides and oxalic acid, a novel liquid-liquid exchange reaction between REE-containing leachate and zinc-loaded Versatic Acid 10 was tested. Finally, a complete flow sheet is proposed for the (almost complete) valorization of REEs as well as the total zinc present.

Binnemans Koen - One of the best experts on this subject based on the ideXlab platform.

  • Integrated process for the recovery of yttrium and europium from CRT Phosphor waste
    'Royal Society of Chemistry (RSC)', 2019
    Co-Authors: Forte Federica, Yurramendi Lourdes, Aldana, José Luis, Onghena Bieke, Binnemans Koen
    Abstract:

    An integrated process flow sheet for the recovery of yttrium and europium from waste cathode-ray tube (CRT) Phosphors was developed. This flow sheet is based on a sequence of roasting, leaching with organic acids and precipitation steps. Zinc was efficiently removed from the roasted CRT Phosphors by leaching with acetic acid, giving access to the rare earth content. Yttrium and europium were quantitatively leached from the residue by a 1 mol L−1 methanesulphonic acid (MSA) solution. Precipitation with oxalic acid gave a mixed Y/Eu oxalate of high purity (>99 wt%). Co-precipitation of zinc was less than 2 wt%.This work has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 680629 (REMAGHIC: New Recovery Processes to produce Rare Earth-Magnesium Alloys of High Performance and Low Cost) (project website: http://www.remaghic-project.eu). The authors acknowledge Relight srl (Rho, Italy) for providing the CRT Phosphor Powder

  • Recovery of rare earths from waste cathode ray tube (CRT) Phosphor Powder by selective sulfation roasting and water leaching
    'Elsevier BV', 2019
    Co-Authors: Onal, Mehmet Ali Recai, Binnemans Koen
    Abstract:

    © 2018 Elsevier B.V. Until recently, most displays, such as television and computer screens, were based on cathode ray tubes (CRTs). With the introduction of new types of displays including liquid crystal displays, CRTs have been widely replaced, leading to a gradual build-up of hazardous CRT Powder waste. In this paper, a new approach is introduced where the valuable rare-earth elements (REEs) (i.e. yttrium and europium) in the Powder are selectively recovered, leaving behind a zinc-rich residue and glass for further recycling. The main rare-earth compound in the waste Powder is Y 2 O 2 S:Eu 3+ (YOS). The fine-grained CRT Powder was mixed with zinc sulfate monohydrate (ZnSO 4 ·H 2 O) and roasted at 600–900 °C for short periods of time. In this way, Y 2 O 2 S:Eu 3+ was transformed into water-soluble rare-earth sulfates. Meanwhile, ZnS underwent a two-stage reaction with ZnSO 4 ·H 2 O, where first a partially water-soluble intermediate (ZnO·2ZnSO 4 ) and then the water-insoluble ZnO was formed. Addition of a sufficient amount of ZnSO 4 ·H 2 O ensured the recovery of ≥95% of the rare earths in a subsequent water leaching step, but there was also co-dissolution of about 5% of the total amount of zinc present. Several purification methods were tested and compared to separate the REEs from the zinc impurity in the solutions. In addition to the conventional precipitation methods with sulfides and oxalic acid, a novel liquid-liquid exchange reaction between REE-containing leachate and zinc-loaded Versatic Acid 10 was tested. Finally, a complete flow sheet is proposed for the (almost complete) valorization of REEs as well as the total zinc present.status: publishe

  • Enhancing rare-earth recovery from lamp Phosphor waste
    'Elsevier BV', 2019
    Co-Authors: Yurramendi Lourdes, Forte Federica, Aldana, José Luis, Gijsemans Lukas, Del Río Carmen, Binnemans Koen
    Abstract:

    In the present work rare-earth recovery was performed from a residue of a hydrometallurgical process based on sulphuric acid leaching of lamp Phosphor waste by which the red Phosphor Y2O3:Eu3+ was removed for further recovery. The undissolved residue is rich in lanthanum, cerium and the valuable terbium, present as phosphates and aluminates in the green and blue Phosphors. The process here proposed is based on an integrated pyro-hydrometallurgical approach involving a thermal treatment (roasting in the presence of sodium carbonate) aimed at converting rare-earth phosphates into oxides, which can be more easily leached by mineral acids (HCl and H2SO4) in a further leaching step. Rare-earth recovery from the leachate was then performed by solvent extraction with the extractant di-(2-ethylhexyl)Phosphoric acid, D2EHPA, followed by precipitation with oxalic acid and calcination. 82% Ce, 75% La and 82% Tb were recovered as mixed La2O3 + CeO2 oxide (99% purity) and Tb4O7 (64% purity).This work has received funding from the European Union's Horizon2020 research and innovation programme under Grant Agreement No.680629 (REMAGHIC: New Recovery Processes to produce Rare Earth-Magnesium Alloys of High Performance and Low Cost) (project website:http://www.remaghic-project.eu/). The authors acknowledge Relightsrl for providing the lamp Phosphor Powder