Browsing by Author "Wilson, Benjamin P., Dr., Aalto University, Finland"
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Item Complexities of Hydrometallurgical Recycling of Spent NiMH and Li-ion Batteries(Aalto University, 2020) Porvali, Antti; Lundström, Mari, Asst. Prof., Aalto University, Finland; Wilson, Benjamin P., Dr., Aalto University, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Hydrometallurgy and Corrosion; Kemian tekniikan korkeakoulu; School of Chemical Technology; Lundström, Mari, Asst. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandNickel metal hydride (NiMH) and lithium ion (Li-ion) batteries are the keystone for many devices in our everyday lives. Their unique chemistry, the very thing that enables them to function as batteries, makes their recycling a complex metallurgical challenge. Improving the understandingof chemical behavior of spent batteries in metallurgical recycling is at the core of this thesis. In this thesis, the recycling, or metallurgical processing, of these two battery types was investigated. Particular emphasis was placed on observing the phenomena associated with the leaching of industrially processed spent batteries. In the case of Li-ion batteries, the resultsobtained from treating industrially processed spent batteries was contrasted to more controlled conditions where synthetic active cathode materials, along with synthetic impurities, were dissolved and studied. Leaching-related chemistry was investigated with both battery types inH2SO4. HCl was briefly investigated with Li-ion batteries. Data was obtained on Fe catalyzed leaching of LiCoO2 in the presence of Cu. The choice of impurities was based on understanding of the composition of spent batteries and industrially processed spent battery scrap. It was shown that under synthetic conditions, dissolved Fe catalyzes the dissolution of Cu and LiCoO2, resulting in extraction rates ranging between 95% - 100% under relatively mild (T = 30 °C, [H2SO4] = 2 M, no H2O2) leaching conditions. In the case of NiMH batteries, the treatment of REEs found in these batteries was investigated by the means of experimentation and process modeling. Their precipitation and removal from the leachate were achieved with the traditional double salt precipitation. Mixed-element crystals were observed in the charcaterization, containing both Na and K in the lattice along with REEs. Their further processing was investigated by NaOH conversion and in-situ Ce oxidation. Ce oxidation degree of 93% was achieved, however limited conversion was observed which was hypothesized of being due to formation of hydroxysulfates resulting from the dissociation of the double salt. Process sidestreams resulting from the REE processing were investigated by the methods of modelling (HSC Chemistry), metamodeling (Regression), and laboratory experiments in order to help understand the relation of process parameters to observed process behaviour. As an overarching theme of the dissertation, the compendium contains suggestions related to methodology through which the spent batteries could be studied more effectively in the future: for instance, thorough the characterization and flexible combinatorial use in research of simulated conditions, manually opened spent batteries, and industrial spent battery streams would be desirable. Forming a comprehensive understanding of the leaching behavior in industrial wastes requires several approaches. The use of flowsheet modeling and a combination of synthetic and industrial material experiments have been shown to be beneficial tools in understanding the planned process system as a whole.Item Performance of Lignin as a Sustainable Anticorrosion Coating(Aalto University, 2022) Dastpak, Arman; Wilson, Benjamin P., Dr., Aalto University, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Hydrometallurgy and Corrosion; Kemian tekniikan korkeakoulu; School of Chemical Technology; Lundström, Mari, Asst. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandSynthetic polymers play a pivotal role in many industrial applications that includes their utilization as barrier coatings for corrosion protection of metal surfaces. However, use of such non-renewable coatings results in environmental pollution both during production and use. As such, there is a global effort to find/produce more sustainable metal coatings from renewable resources including biomass-based polymers. Consequently, this thesis investigates the performance of technical lignin—a primary waste from biomass processing industries—as an organic binder in anticorrosion coatings, with a focus on the industrial applicability of these materials and associated deposition techniques. Electrochemical properties of stainless steel spin-coated with two different organosolv lignin (dissolved in 1,4-Dioxane) were investigated. Results showed that the coatings enhanced the resistance of surfaces against corrosion with a lignin source-dependent variation of the barrier properties. In order to address the limited lignin solubility in many organic solvents, the screening of a series of industrially-applicable organic solvents was undertaken. Findings indicated that two solvents—diethylene glycol monobutyl ether (DEGBE) and propylene glycol monomethyl ether (PGME)—act as strong solvents for a kraft and an organosolv lignin, and that DEGBE also has a plasticizing effect on lignin. However, electrochemical analysis of lignin-coated steel prepared from PGME following prolonged immersion (24 hours) in 5 wt.% NaCl, showed that these coatings offer limited protection. Furthermore, cracking of lignin-PGME coatings was observed, which was found to be mitigated by addition of triethyl citrate (TEC) as a plasticizer. An alternative and more environmentally benign route for the preparation of lignin-based coatings was further achieved by the preparation of aqueous dispersions of colloidal lignin particles (CLPs) using DEGBE as the starting solvent in a solvent-exchange procedure. Consequently, it was possible to prepare combined lignin-cellulose composite coatings using electrophoretic deposition (EPD) from aqueous dispersions at low deposition potentials, and resulted in coatings with enhanced durability during long term immersion (15 days) in 3.5 wt.% NaCl electrolyte. An important outcome of this process was the coalescense of CLPs during drying—as a result of the DEGBE—that enabled the formation of compact coatings. Such techniques and coalescing characteristics could be exploited in the preparation of water-borne lignin layers with enhanced corrosion protection capabilities as part of a future fully sustainable coating formulation.