Solar thermal treatment of manganese ores

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dc.contributor.advisorDinter, Franken_ZA
dc.contributor.advisorMcGregor, Craigen_ZA
dc.contributor.advisorReynolds, Quinnen_ZA
dc.contributor.authorHockaday, Aletta Carolinaen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.en_ZA
dc.date.accessioned2023-03-02T06:56:16Z
dc.date.accessioned2023-05-18T07:01:05Z
dc.date.available2023-03-02T06:56:16Z
dc.date.available2023-05-18T07:01:05Z
dc.date.issued2023-03
dc.descriptionThesis (PhD)--Stellenbosch University, 2023. en_ZA
dc.description.abstractENGLISH SUMMARY: The use of sunlight as an alternative energy source is well established in the electricity sector, but mineral processing has lagged in adopting renewable energy sources. Specifically, the combustion of fossil fuels for process heat and using coal as a reductant are still the norm. It is possible to heat minerals directly with concentrating solar technology. Simultaneously, thermal decomposition reactions can cause the removal of oxygen or the decomposition of carbonate minerals without reductants. The use of concentrating solar technology for the pre-treatment of manganese ores was investigated in this light. Pre-heating, calcination and pre-reduction were identified as processes within the temperature range achievable by solar particle receivers. Manganese ores differ in the amount of carbonate minerals present and in the degree of oxidation of manganese. After chemical and mineralogical assaying of three South African manganese ores, their behaviour was investigated in thermogravimetric laboratory experiments. Tests were also done using a rooftop flat mirror parabolic dish concentrator to confirm that the laboratory studies may be used to inform the ores’ behaviour in on-sun conditions. Comparing the mass loss achieved during experiments to expected mass loss under equilibrium conditions, it was clear that mass loss was kinetically limited at temperatures below 950 °C. A dynamic reaction rate model was formulated from published literature to explain the ore behaviour in this temperature range. The model was validated against the measured mass loss data from all the experiments. Scaling of the technology was investigated for a 2.5 MWt solar plant. A radiation view factor model was formulated describing the rotary solar receiver energy flows. The reaction rate model was incorporated into this dynamic process model, enabling the calculation of the material composition in each receiver zone and for the products. The model was evaluated for daily and monthly periods in minute timesteps. The products were shown to produce energy savings and reduce greenhouse gas emissions when used in high-carbon ferromanganese production. The solar thermal plant process model showed that a 2.5 MWt solar plant can treat 5800 to 10600 metric tons of manganese ore per year at a levelised cost of heat of 380 R/MWh for 20-year project life. At the same time, while avoiding greenhouse gas emissions, this energy cost is lower than that of electric heating and heating with diesel combustion.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die gebruik van sonlig as 'n alternatiewe energiebron is goed gevestig in die elektrisiteit sektor, maar mineraalverwerking het agterwee gebly in die aanvaarding van hernubare energiebronne. Spesifiek, die verbranding van fossielbrandstowwe vir proses verhitting en die gebruik van steenkool as reduktant is steeds die norm. Dit is moontlik om minerale direk te verhit met konsentrerende son tegnologie. Terselfdertyd kan termiese ontbindings reaksies die verwydering van suurstof en die ontbinding van karbonaat minerale sonder reduktante bewerk. Die gebruik van konsentrerende son tegnologie vir die voorbehandeling van mangaan ertse is in hierdie lig ondersoek. Voorverhitting, kalsinering en reduksie was geidentifiseer as prosesse binne die temperatuur bereik wat deur partikel son reaktors haalbaar is. Mangaan ertse verskil in die hoeveelheid karbonaat minerale wat teenwoordig is en in die oksidasie graad van mangaan. Nadat drie Suid-Afrikaanse mangaan ertse chemiese en mineralogies getoets was, was hul gedrag in termogravimetriese laboratorium eksperimente ondersoek. Toetse was ook gedoen met behulp van 'n paraboliese skottel konsentrator om te bevestig dat die laboratorium studies gebruik kan word om die ertse se gedrag in son verhitting te beskryf. Deur die massaverlies tydens eksperimente te vergelyk met verwagte massaverlies onder ewewigstoestande, was dit duidelik dat massaverlies kineties beperk was by temperature onder 950 °C. 'n Dinamiese reaksietempo model is uit gepubliseerde literatuur geformuleer om die erts gedrag vir hierdie temperature te beskryf. Die model is gevalideer teen die gemete massaverlies data van al die eksperimente. Die skaal van die tegnologie is ondersoek vir 'n 2,5 MWt-sonkrag aanleg. 'n Roterende son reaktor is deur 'n stralings aansig faktor model beskryf. Die reaksietempo model is in hierdie dinamiese proses model opgeneem, wat die berekening van die materiaal samestelling in elke reaktor sone en vir die produkte moontlik gemaak het. Die model is geevalueer oor daaglikse en maandelikse tydperke in minuut tyd stappe. Daar was getoon dat die produkte energie besparing en 'n vermindering van kweekhuis gas vrystellings bewerk wanneer dit gebruik word in hoe koolstof ferromangaan produksie. Die son termiese aanleg proses model het getoon dat 'n 2,5 MWt-sonkrag aanleg 5800 tot 10600 ton mangaanerts per jaar kan behandel teen 'n gelykgemaakte verhittings koste van 380 R/MWh vir 'n projek tydperk van 20 jaar.af_ZA
dc.description.versionDoctorate
dc.format.extentxx, 177 pages : illustrations, maps, includes annexures
dc.identifier.urihttp://hdl.handle.net/10019.1/127034
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch University
dc.rights.holderStellenbosch University
dc.subject.lcshManganese oresen_ZA
dc.subject.lcshSolar thermal energyen_ZA
dc.subject.lcshSolar heatingen_ZA
dc.subject.lcshRenewable energy sourcesen_ZA
dc.subject.nameUCTD
dc.titleSolar thermal treatment of manganese oresen_ZA
dc.typeThesisen_ZA
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Doctoral Degrees (Mechanical and Mechatronic Engineering)