Feasibility of an efficient recovery of rare earth-activated phosphors from waste fluorescent lamps through dense-medium centrifugation

Hirajima, Tsuyoshi; Sasaki, Keiko; Bissombolo, Abel; Hirai, Hisao; Hamada, M.; Tsunekawa, Masami

doi:10.1016/j.seppur.2004.12.014

Cited by 70 publications

(28 citation statements)

References 11 publications

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“…Figure 5 shows that Al 3+ and Fe 3+ , which started to hydrolyze when the pH was 3.08 and 1.62, respectively, can be removed effectively by adjusting the pH of leaching solution. The Al(OH) 3 and Fe(OH) 3 generated were stable and not easy to dissolve because of their large solubility product constant; however, the pH cannot be too high, otherwise it may contribute to the loss of rare earth metals. Figure 6 reports the relationship between pH and the yields of impurities and rare earth metals.…”

Section: Impurities Removal With Ammoniamentioning

confidence: 99%

“…Tsuyoshi Hirajima et al [2] used collecting agents and dispersants to separate rare earth trichromatic fluorescent phosphors by flotation method. Hirajima et al [3] used diazomethane as the layered medium and sodium oleate as a surfactant to recycle rare earth fluorescent phosphors by centrifugal separation method. Akira Otsuki et al [4] adopted two-step liquid-liquid extraction methods to separate red, green, and blue rare earth…”

Section: Introductionmentioning

confidence: 99%

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Recycling Y and Eu from Waste Fluorescent Powder and High Temperature Solid-State Synthesis of Y2O3:Eu Phosphors

et al. 2017

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Y 2 O 3 :Eu were prepared through precursors synthesized by leaching tests, removing impurities, enrichment of Y and Eu from residual purified liquors, annealing treatment, and high temperature solid-state reaction method, which is the most suitable for large-scale production. The analysis of product shows that the purity is 99.42%. The resultant powders were characterized by X-ray diffraction (XRD), differential thermal analysis (TG-DTA), scanning electron microscope (SEM), and photoluminescence (PL). Compared with the commercial phosphors, the XRD spectrum of the product samples revealed the synthesized particles to have a pure cubic Y 2 O 3 :Eu structure without any impurities in the crystalline phase. On the morphology, the Y 2 O 3 :Eu particles synthesized by a combustion and high temperature solid state process with sintering aids, were large and uniform. For luminescence property, the emission intensity of Y 2 O 3 :Eu phosphors synthesized by combustion process and high temperature solid state process with sintering aids were higher than those without sintering aids, at 1400 • C.

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Section: Impurities Removal With Ammoniamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recycling Y and Eu from Waste Fluorescent Powder and High Temperature Solid-State Synthesis of Y2O3:Eu Phosphors

et al. 2017

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“…This technology is based on the phenomenon of fluorescence, which is why this type of lamp is commonly known as fluorescent lamps. In order to produce this phenomenon it is necessary to introduce certain chemicals inside the lamp with which produce it, namely, liquid mercury and phosphor powder (Hirajima et al, 2005). Due to the use of this heavy metal, fluorescent lamps are also known as mercury lamps.…”

Section: Introductionmentioning

confidence: 99%

Determination of mercury distribution inside spent compact fluorescent lamps by atomic absorption spectrometry

Rey‐Raap

Gallardo

2012

Waste Management

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a b s t r a c tIn this study, spent compact fluorescent lamps were characterized to determine the distribution of mercury. The procedure used in this research allowed mercury to be extracted in the vapor phase, from the phosphor powder, and the glass matrix. Mercury concentration in the three phases was determined by the method known as cold vapor atomic absorption spectrometry. Median values obtained in the study showed that a compact fluorescent lamp contained 24.52 ± 0.4 ppb of mercury in the vapor phase, 204.16 ± 8.9 ppb of mercury in the phosphor powder, and 18.74 ± 0.5 ppb of mercury in the glass matrix. There are differences in mercury concentration between the lamps since the year of manufacture or the hours of operation affect both mercury content and its distribution. The 85.76% of the mercury introduced into a compact fluorescent lamp becomes a component of the phosphor powder, while more than 13.66% is diffused through the glass matrix. By washing and eliminating all phosphor powder attached to the glass surface it is possible to classified the glass as a non-hazardous waste.

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“…Recycling of the rare earth elements, such as Y, Eu, La, Ce and Tb is not considered practical due to the lack of an available method [1]. Also, experiments are made with waste phosphors collected during the recycling of end-of-life fluorescent lamps to obtain a highly enriched phosphors product as a starting material for the better extraction of rare earth elements [2]. Fluorescent lamps can be recycled by crushing the tubes and splitting them into component parts, allowing mercury and other components (mainly glass) to be recovered [3].…”

Section: Introductionmentioning

confidence: 99%

New technology for waste fluorescent lamps treatment in Lithuania—characterisation and environmental impact

Urniežaitė¹,

Jankūnaitė²,

Griškonis³

2007

WIT Transactions on Ecology and the Environment, Vol 106

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Treatment of waste fluorescent lamps, which are widely used all over the world, is a very important field of environmental research. Due to the presence of mercury vapour in these lamps, this kind of waste requires special attention to its disposal. This study aims to evaluate the environmental impact of fluorescent lamps and to describe the principal aspects of new technology used for their treatment in Lithuania.The main parameters in this treatment process are mercury and manganese concentrations in the treatment of residual waste of fluorescent lamps. Mercury concentration in fractionated treatment residuals was determined by complexonometric titration and the manganese concentration was determined by the atomic absorption method. The results, obtained in the study, show manganese and mercury content in fluorescent lamp treatment products and the main physical parameters of these treatment products. This study revealed that concentrations of metallic mercury and water soluble mercury salts in the examined samples are within the permitted limits. Also, this paper presents residuals X-ray analysis results.Results of this study show that the products of waste fluorescent lamps treatment can be treated as environmentally friendly, according to their solubility in water. It gives an opportunity to look for more possibilities of this product's disposal. As the presented treatment technology is relatively new and used to treat only small amounts of waste fluorescent lamps, this technology could be modified for larger productivity. Studies of this technology should go further in the aspects of different ways of treating the disposal of products, development of technology, etc.

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Feasibility of an efficient recovery of rare earth-activated phosphors from waste fluorescent lamps through dense-medium centrifugation

Cited by 70 publications

References 11 publications

Recycling Y and Eu from Waste Fluorescent Powder and High Temperature Solid-State Synthesis of Y2O3:Eu Phosphors

Recycling Y and Eu from Waste Fluorescent Powder and High Temperature Solid-State Synthesis of Y2O3:Eu Phosphors

Determination of mercury distribution inside spent compact fluorescent lamps by atomic absorption spectrometry

New technology for waste fluorescent lamps treatment in Lithuania—characterisation and environmental impact

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