Integrated development and optimisation of an organic acid-based hydrometallurgical process for treatment of spent lithium-ion batteries (LIBs)

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dc.contributor.advisorAkdogan, Guvenen_ZA
dc.contributor.advisorDorfling, Christieen_ZA
dc.contributor.authorJeza, Sabelo Acceptanceen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Process Engineering.en_ZA
dc.date.accessioned2022-03-09T08:46:55Zen_ZA
dc.date.accessioned2022-04-29T09:36:55Zen_ZA
dc.date.available2022-03-09T08:46:55Zen_ZA
dc.date.available2022-04-29T09:36:55Zen_ZA
dc.date.issued2022-04en_ZA
dc.descriptionThesis (MEng)--Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH SUMMARY: Lithium-ion batteries (LIBs) are the heart of some of the latest technological devices but these batteries become harmful waste at the end of their life. At present, the use of organic acid-based hydrometallurgy processing of spent LIBs is the most promising alternative route to pyrometallurgical processing in terms of economic feasibility and environmental impact. This study aimed to develop an integrated and optimised organic acid-based hydrometallurgical process for the treatment of LIBs to recover metals at end-of-life. This was achieved by conducting leaching, precipitation and solvent extraction batch experiments in a specific order, followed by flowsheet modelling using experimentally obtained values and techno-economic analysis to assess potential feasibility. Citric acid was selected as the organic acid with which to leach LIBs at a constant temperature of 95 °C, while stirring at 750 rpm, with a S/L ratio of 20 g/L and 2 vol. % H2O2. The effect of lixiviant concentration (0.75 M, 1 M, 1.5 M, 2 M and 3 M) on metal equilibrium extraction was also investigated. The concentration of 0.75 M resulted in equilibrium metal extraction of 94.3% Li, 95.1% Co, 96.2% Mn and 95.7% Ni after 1 hour. Ni was the first metal to be recovered through precipitation from a leachate solution using 0.07 M dimethyl glyoxime (DMG) at a pH of 6, followed by the solvent extraction of Mn using 10% D2EHPA at an O/A ratio of 3 and a pH of 5. Mn was stripped from the organic phase using 0.5 M H2SO4 at an O/A ratio of 1.33 followed by hydroxide precipitation. The aqueous phase from Mn solvent extraction mainly consisted of Co which was precipitated using NaOH at a pH of 13.5. Four process products were recovered: Ni(OH)2 with more than 99.5% purity and 62.7% Ni recovery; Mn(OH)2 with 89% purity and 90.2% recovery; Li2SO4 with 97% purity and 57.3% Li recovery and cobalt hydroxide based product (Co(OH)2) with 68 % purity and 71.4% Co recovery. A feed rate of 868 tonnes per year was used for the flowsheet modelling, based on the South African context in terms of expected LIBs waste, and this resulted in an estimated annual revenue of R190 023 414. The estimated capital expenditure was R162 920 270 and the operating expenditure was R88 148 631. An NPV value of R241 272 740 over a 10-year investment period was discounted at 11.11%, equivalent to a 67.95% IRR, which implies that the process would be profitable upon implementation.en_ZA
dc.description.abstractAFRIKAANS OPSOMMING: Litiumioonbatterye (LIBs) is die hart van sommige van die nuutste tegnologiese toestelle, maar hierdie batterye word skadelike afval aan die einde van hul lewe. Tans is die gebruik van organiese suurgebaseerde hidrometallurgiese prosessering van gebruikte LIBs die mees belowende alternatiewe roete vir pirometallurgiese prosessering in terme van ekonomiese uitvoerbaarheid en omgewingsimpak. Hierdie studie het beoog om ’n geïntegreerde en geoptimeerde organiese suurgebaseerde hidrometalllurgiese proses vir die behandeling van LIBs te ontwikkel om metale aan die end-van-lewe te herwin. Hierdie is bereik deur loging, presipitasie en oplosmiddelekstraksie uit te voer, gevolg deur vloeidiagrammodellering deur eksperimenteel verkrygde waardes en tegno-ekonomiese analise te gebruik om potensiële uitvoerbaarheid te assesseer. Sitroensuur is gekies as die organiese suur waarmee LIBS by ’n konstante temperatuur van 95 °C, terwyl geroer word by 750 rpm, met ’n S/L-ratio van 20 g/L en 2 vol.% H2O2 geloog sou word. Die effek van loogmiddelkonsentrasie (0.75 M, 1 M, 1.5 M, 2 M en M) op metaalekwilibriumekstraksie is ook ondersoek. Die konsentrasie van 0.75 M het ekwilibriummetaalekstraksie van 94.% Li, 95.1% Co, 96.2% Mn en 95.7% Ni na een uur tot gevolg gehad. Ni was die eerste metaal om herwin te word deur presipitasie uit ’n uitloogseloplossing deur 0.07 M dimetiel glioksiem (DMG) by pH 6 te gebruik, gevolg deur die oplosmiddelekstraksie van Mn deur 10% D2EHPA by O/A-ratio van 3 en ’n pH van 5 te gebruik. Mn is gestroop van die organiese fase deur 0.5 M H2SO4 by ’n O/A-ration van 1.3 te gebruik, gevolg deur hidroksiedpresipitasie. Die waterige fase van Mn-oplosmiddelekstraksie het hoofsaaklik bestaan uit Co wat gepresipiteer is deur NaOH by ’n pH van 13.5 te gebruik. Vier prosesprodukte is herwin: Ni(OH)2 met meer as 99.5% suiwerheid en 62.7% Ni-herwinning; Mn(OH)2 met 89% suiwerheid en 90.2%-herwinning; Li2SO4 met 97% suiwerheid en 57.% Liherwinning en kobalthidroksiedgebaseerde produk (Co(OH)2) met 68% suiwerheid en 71.4% Co-herwinning. ’n Voertempo van 868 ton per jaar is gebruik vir die vloeidiagrammodellering, gebaseer op die Suid-Afrikaanse konteks in terme van verwagte LIB-afval, en hierdie het ’n beraamde jaarlikse inkomste van R190 023 414 tot gevolg gehad. Die beraamde kapitale uitgawe was R162 920 270 en die bedryfskoste was R88 148 61.en_ZA
dc.description.versionMastersen_ZA
dc.format.extentxxviii, 174 pages : illustrationsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/124852en_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectLithium ion batteriesen_ZA
dc.subjectLeachingen_ZA
dc.subjectMetals -- Recyclingen_ZA
dc.subjectUCTDen_ZA
dc.titleIntegrated development and optimisation of an organic acid-based hydrometallurgical process for treatment of spent lithium-ion batteries (LIBs)en_ZA
dc.typeThesisen_ZA
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