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dc.contributor.advisorMishra, Brajendra
dc.contributor.authorEduafo, Patrick Max
dc.date.accessioned2016-02-23T18:12:12Z
dc.date.accessioned2022-02-03T12:56:07Z
dc.date.available2016-02-23T18:12:12Z
dc.date.available2022-02-03T12:56:07Z
dc.date.issued2016
dc.identifierT 7995
dc.identifier.urihttps://hdl.handle.net/11124/170056
dc.description2016 Spring.
dc.descriptionIncludes illustrations (some color).
dc.descriptionIncludes bibliographical references.
dc.description.abstractCharacterization techniques and experimental measurements were used to evaluate a process for recycling rare earth elements (REEs) from spent fluorescent lamp phosphors. QEMSCAN analysis revealed that over 60% of the rare earth bearing minerals was less than 10 µm. A representative sample of the as-received feed contained 14.59 wt% total rare earth elements (TREE) and upon sieving to below 75 µm, the grade increased to 19.60 wt% REE with 98.75% recovery. Based on experimental work, a new process for extracting the chief REEs from end of life fluorescent lamps has been developed. The proposed flowsheet employs a three-stage leaching and precipitation process for selective extraction and recovery of the REEs. Hydrochloric acid was used as lixiviant in batch leach experiments on the phosphor powder. The maximum extraction obtained was 100% for both yttrium and europium under the following leaching conditions: 2.5 M HCl, 70˚C, 1 hour, 180 g/L and 600 rpm. However, the solubility of cerium, lanthanum and terbium remained low at these conditions. Kinetic data of the leaching of yttrium and europium showed best fit to the logarithmic rate expression of the empirical model of leaching. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298 to 343 K. Precipitation tests demonstrate that at least 50% excess the stoichiometric amount of oxalic acid is needed to recover yttrium and europium efficiently to produce a pure (Y, Eu) mixed oxide. Total recovery of the REEs was achieved even at very low pH or without any base added. Over 99% pure mixed rare earth oxide at 99% recovery has been attained. An economic assessment of the developed process using operating and capital cost have be undertaken and based on the analysis of the three economic scenarios, two are economic and one is non-economic.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2010-2019 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectfluorescent lamp
dc.subjectlamp phosphor
dc.subjectleaching
dc.subjectprecipitation
dc.subjectrare earth elements
dc.subjectrecycling
dc.titleInvestigation of recovery and recycling of rare earth elements from waste fluorescent lamp phosphors
dc.typeText
dc.contributor.committeememberTaylor, Patrick R.
dc.contributor.committeememberAnderson, Corby G.
dc.contributor.committeememberEggert, Roderick G.
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineMetallurgical and Materials Engineering
thesis.degree.grantorColorado School of Mines
dc.rights.accessEmbargo expires: 2018-02-24


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