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dc.contributor.advisorPurcell, W.
dc.contributor.advisorVenter, J.
dc.contributor.authorMnculwane, Hlengiwe Thandekile
dc.date.accessioned2016-09-01T12:04:17Z
dc.date.available2016-09-01T12:04:17Z
dc.date.issued2016-01
dc.identifier.urihttp://hdl.handle.net/11660/4035
dc.description.abstractEnglish: The main objective of this study was to develop an analytical method to accurately quantify scandium in different Sc-containing matrices including inorganic compounds, organometallic complexes and finally low grade Sc mineral ores and residues. The organometallic complexes (Sc(acac)3, Sc(tfac)3, Sc(btfac)3, Sc(dbm)3, Sc(hfac)3 and Sc(sacac)3) were synthesized and characterised using melting point, IR, CHNS-micro element analysis and X-ray crystallography techniques. The study involved the use of different mineral acids such as HNO3, HCl and H2SO4 for the dissolution of the different samples using both open-beaker and microwave-assisted dissolution techniques. Flux fusion using NH4F·HF flux was used for the dissolution of columbite mineral and Ta/Nb residue samples. ICP-OES was used for quantification of Sc in all samples as well as some of the other metals in the mineral samples. The wavelengths were carefully selected to minimise any spectral interferences and the matrix matching was also ensured throughout the study for accurate measurements. ScCl3·H2O was dissolved in water and recoveries ranging from 99.64 - 99.79 % were obtained. Open-beaker dissolution of Sc2O3 with HNO3, HCl or H2SO4 yielded Sc recoveries ranging from 44(7) - 99.2(4) % and these recoveries were improved with the microwave dissolution method to recoveries between 99.8(3) and 101(1) %. Excellent Sc recoveries from the most of the organometallic complexes (Sc(acac)3, Sc(tfac)3, Sc(btfac)3, Sc(dbm)3 and Sc(sacac)3) ranging from 95(3) - 99.4(6) % were obtained while Sc(hfac)3 yielded a lower than expected recovery of 80.4(4) % due to the possibility that the molar mass from the empirical formula known is incorrect or that an impure product was isolated. Excellent results were obtained for the columbite ore and the Ta/Nb residue samples (Sample A and B respectively) after the NH4F·HF fusion dissolution. In the process of the beneficiation of Sc, magnetic separation was attempted for the removal of Fe and Ti from the rest of the sample (both Sample A and Sample B) but was considered unsatisfactory since a large portion of the Fe in the sample did not exhibit ferromagnetic properties and hence remained with the original portion (nonmagnetic) of the samples. Results also indicated the loss of a relatively significant portion of Sc in both samples. Solvent extraction with MIBK was also attempted for the possible extraction of Ta and Nb and the results indicated that this process was only successful to eliminate the Ta in large quantities and that both the Ta and Nb can be extracted with MIBK at high [H2SO4] with relatively insignificant losses of Sc, especially from Sample B. The experimental results for the scandium analysis were validated for a large number of validation parameters, which included accuracy, precision, sensitivity, specificity, linearity, etc. to confirm whether the newly developed analytical procedures were suitable for the scandium determination in terms of internationally required standards (ISO 17025). The limit of detection (LOD) and limit of quantitation (LOQ) for Sc were determined to be 0.000991and 0.00991 ppm respectively, which is sufficient to measure trace amounts of scandium. The linearity of the calibration curves was determined from the regression coefficient (R2) and ranged from 0.996 to 1.00. Statistical tests of the experimental results were calculated using the hypothesis test of the t-statistical at 95 % confidence interval (C.I) to determine whether the results were acceptable as recommended by ISO 17025.en_ZA
dc.description.abstractAfrikaans: Die primêre doel van hierdie studie was om 'n analitiese metode te ontwikkel om skandium akkuraat in verskillende Sc-bevattende matrikse, insluitend anorganiese verbindings, organometaalkomplekse en uiteindelik lae graad Sc minerale erts en prosesafval-materiaal te kwantifiseer. ʼn Aantal organometaalkomplekse, naamlik Sc(acac)3, Sc(tfac)3, Sc(btfac)3, Sc(dbm)3, Sc(hfac)3 en Sc(sacac)3 is tydens die studie berei en met behulp van smeltpunt, IR, CHNS mikro-element analise en Xstraalkristallografie tegnieke gekarakteriseer. Verder is die vertering van die verskillende monsters met behulp van beide gewone oop beker en mikrogolfvertering in die teenwoodigheid van ‘n aantal HNO3, HCl en H2SO4 ondersoek. Die vertering en oplos van die kolumbiet minerale monster en die Ta/Nb prosesafval monsters is ook met gesmelte sout of vloeimiddelsmelting ondersoek en NH4F∙HF is hoofsaaklik as smeltmiddel gebruik. In alle gevalle is IGP-OES is vir die akkurate bepaling van die hoeveelheid Sc en ander elemente in al die anorganiese verbindings, organometaalkomplekse asook in die minerale monsters gebruik. Die golflengtes vir hierdie bepalings is sorgvuldig gekies om enige spektrale steurings te verhoed en in alle gevalle is matriksparing toegepas om die moontlike invloed van al die bygevoegde chemikalië in die Sc-bepaling uit te skakel. Die ScCl3·H2O los maklik op in water en Sc-opbrengste wat tussen 99.64 - 99.79 % wissel, is verkry. Die natvertering van Sc2O3 in HNO3, HCl of H2SO4 het Sc-opbrengste wat wissel tussen 44(7) - 99.2(4) % gelewer. Die gebruik van mikrogolfvertering in die teenwoordigheid van dieselfde sure het die Sc-opbrengste tot 99.8(3) en 101(1) % verbeter. Uitstekende Sc-opbrengste is vir die meerderheid organometaalkomplekse ((Sc(acac)3, Sc(tfac)3, Sc(btfac)3, Sc(dbm)3 en Sc(sacac)3) verkry met Sc-waardes wat tussen 95(3) en 99.4(6) % gewissel het, terwyl heelwat laer Sc-opbrenste (80.4(4) %) vir Sc(hfac)3 verkry is. Moontlike redes vir hierdie laer opbrengste kan moontlik aan die gebruik van ʼn verkeerdelike molêre massa of empiriese formule of dat ʼn onsuiwere produk geïsoleer is, toegeskryf word. Die magnetiese skeiding van Fe en Ti in beide die kolumbiet erts en die Ta/Nb prosesafval-materiaal was onbevredigend met ʼn groot hoeveelheid van die yster wat in die nie-magnetiese gedeelte agtergebly het asook betekenisvolle Sc-hoeveelhede wat in die magnetiese gedeelte verlore geraak het. Uitstekende Sc-resultate is na die NH4F∙HF vloeimiddelsmeltinig vertering vir die beide die kolumbiet erts en die Ta/Nb prosesafval-materiaal verkry. Resultate het ook die verlies van 'n relatief beduidende gedeelte van Sc in beide monsters aangedui. Die skeiding van Ta en Nb in beide die kolumbiet erts en die Ta/Nb prosesafval-materiaal met behulp van MIBK oplosmiddel-ekstraksie ondersoek. Die resultate het aangedui dat hierdie proses suksesvol is om al die Ta in beide monsters te verwyder, met relatief onbeduidende verliese van Sc. Die eksperimentele resultate vir die Sc- analise is vir 'n groot aantal valideringsparameters volgens ISO 17025 kriteria, wat onder andere akkuraatheid, presisie, sensitiwiteit, spesifisiteit, lineariteit ens. insluit, geëvalueer. Die beperking/grens van die opsporing (LOD) en laagste vlak van kwantifisering (LOQ) vir Sc was 0.000991 en 0.00991 dpm onderskeidelik bepaal. Die lineariteit van al die kalibrasie kurwes (regressie-koëffisiënt, R2) het tussen 0.996 - 1.00. gevarieer. Verdere statistiese toetse vir al die eksperimentele resultate is met behulp van ʼn hipotese toets (t-toets met ʼn op 95 % betroubaarheidsinterval) geëvalueer.af
dc.description.sponsorshipMINTEKen_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectDissertation (M.Sc. (Chemistry))--University of the Free State, 2016en_ZA
dc.subjectScandiumen_ZA
dc.subjectQuantative analysisen_ZA
dc.subjectQualitative analysisen_ZA
dc.titleScandium quantification in selected inorganic and organometallic compoundsen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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