Browsing by Author "Kupi, Aleksanteri"
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- Kinetic study of LiOH production from leached Li-ore
Kemian tekniikan korkeakoulu | Master's thesis(2024-05-21) Kupi, AleksanteriShift towards renewable energy sources has led to an increase in demand of metals needed for associated technologies. Especially lithium ion batteries are in great demand due to their use in electric vehicles as power storage. Consequently, production of lithium ion battery precursors, lithium hydroxide and lithium carbonate, are expected to increase to meet the demand. Metso, a metallurgical engineering company, has patented an alkaline two-stage leaching process for the production of lithium hydroxide from beta-spodumene concentrate. The process is in the phase of commercialization in Finland and United States. It has an average lithium yield of over 90%. Further improvements to the process could be achieved by modeling the kinetics, starting with conversion leaching of Li2CO3 into LiOH. In the literature review, current alkaline methods of LiOH · H2O production were studied. The common unit operations were outlined, and Metso’s patented LiOH · H2O process was discussed. More detailed literature review of conversion leaching was conducted. Traditional kinetic process modeling workflow was discussed. Conversion leaching experiments were performed at Metso Research Center in Pori. The raw material of the experiments was soda leaching filter cake originating from spodumene. Lime milk was used to leach Li2CO3 into LiOH. The experiments had a lithium yield in the range of 80.2–94.5%. Higher stirring speed increased the lithium yield. Temperature did not have a distinguishable trend. Lower soda leaching cake amount increased the lithium yield. Higher Ca(OH)2:Li2CO3 ratio and shorter lime milk pump time increased the leaching rate and lithium yield. Kinetic model for the conversion leaching was developed using a novel method, which combined HSC Sim process modeling software and Python code with the help of proprietary HSC-Python API. A dynamic, isothermal, and perfectly mixed conversion leaching reactor model was created in HSC Sim. Six relevant reactions and their associated rate equations were implemented in the model. Python was used for data pre-processing, implementing a parameter optimizer, setting initial guesses for the kinetic parameters, and activating the relevant reactions. A modified Arrhenius equation was used as the basis for the kinetic parameter estimation. The model optimized the fit of the simulated data to the experimental data with the least squares method. The best-fit scenario had a coefficient of determination R2 of 95.0%. The kinetic parameters had acceptable confidence interval error, and the correlations between the parameters were low. The best-fit reaction mechanism was in-situ ion exchange on Li2CO3 surface, with Ca2+ attacking lithium, leaching lithium to the solution and precipitating CaCO3. Additionally, Li2CO3 equilibrium solubility reaction was used. - Tellurium cementation from copper anode slime leachate
Kemiantekniikan korkeakoulu | Bachelor's thesis(2022-05-08) Kupi, Aleksanteri