Periodic Reporting for period 1 - ELECTROION (Process engineering for sustainable recovery of valuable metals by ELECTRO-IONometallugy)
Período documentado: 2021-07-01 hasta 2023-06-30
The project focussed on the use of Ionometallurgy, as a potential resource efficient and methodology for selective metal recovery. It uses non-aqueous ionic solvents such as deep eutectic solvents (DESs), which are mixtures of Lewis acids and bases. These have several advantages over traditional ionic liquids, such as low cost and ease of preparation from readily available components. Thus, metals can be directly recovered from minerals by following a similar principle than the traditional hydrometallurgical route, but with higher selectivity and lower toxicity. This is enabled by the use of a largely non-aqueous environment, where solvation is controlled by the anion and the hydrogen bond donor (HBD) of the DES.
The main goal was to develop a non-aqueous, electrocatalytic processing technology able to efficiently and economically recover metals from solid matrixes using ionometallurgy.
The main goal was to develop a non-aqueous, electrocatalytic processing technology able to efficiently and economically recover metals from solid matrixes using ionometallurgy.
DESs have several advantages over traditional solvents, such as low cost and ease of preparation from readily available components.
The integration of DES with a oxidising agent enables to selectively separate metals from a substrate (e.g. PCBs or solar photovoltaic cells). BUT the process is mass transfer limited due to the high viscosity of the solvent (> 40 mPa s).
Addition of water can help reducing viscosity, which can be beneficial or not for improving selectivity. Ultrasound also demonstrated fast dissolution rate in DESs, but further investigation is still required.
Brines demonstrated promising results for leaching metals as a replacement for traditional mineral acids and DESs. This type of solvent tends to have high water content by which they are characterised by having lower viscosity in comparison to ionic fluids.
Secondment at Metso Research Centre (Pori – Finland)
The secondment lasted 2 months, and the main goal was to learn Process Simulations by using the Metso's chemical reaction and equilibrium software HSC Chemistry.
Exploitation of results and dissemination
The results obtained during this project were considered not suitable for IP protection and, thus, they were disseminated through conference presentations (e.g. 61st Conference of Metallurgists, Collaborative Network for X-Ray Spectroscopy – CONEX) and peer-reviewed publications. Most of the publications have been made available (green open access) through archiving in perpetuity on the Leicester Research Archive.
In addition, the results of the project were also transferred to a much wider audience through the following actions:
• Dissemination through social media (i.e. Facebook, Twitter, ResearchGate and LinkedIn).
• Update of the Wikipedia page on extractive metallurgy, as now the description of ionometallurgy is also included.
• Presentations of general aspects on ionometallurgy via local scientific events, such as the British Science Festival and Pint of Science, version 2022. Results of public and policy interest have been disseminated via news articles: https://www.bbc.co.uk/newsround/62886797
In addition, this new knowledge is currently being used as educational and training material within the Centre for Sustainable Material Processing and the Centre for Sustainable Resource Extraction, at the University of Leicester.
The integration of DES with a oxidising agent enables to selectively separate metals from a substrate (e.g. PCBs or solar photovoltaic cells). BUT the process is mass transfer limited due to the high viscosity of the solvent (> 40 mPa s).
Addition of water can help reducing viscosity, which can be beneficial or not for improving selectivity. Ultrasound also demonstrated fast dissolution rate in DESs, but further investigation is still required.
Brines demonstrated promising results for leaching metals as a replacement for traditional mineral acids and DESs. This type of solvent tends to have high water content by which they are characterised by having lower viscosity in comparison to ionic fluids.
Secondment at Metso Research Centre (Pori – Finland)
The secondment lasted 2 months, and the main goal was to learn Process Simulations by using the Metso's chemical reaction and equilibrium software HSC Chemistry.
Exploitation of results and dissemination
The results obtained during this project were considered not suitable for IP protection and, thus, they were disseminated through conference presentations (e.g. 61st Conference of Metallurgists, Collaborative Network for X-Ray Spectroscopy – CONEX) and peer-reviewed publications. Most of the publications have been made available (green open access) through archiving in perpetuity on the Leicester Research Archive.
In addition, the results of the project were also transferred to a much wider audience through the following actions:
• Dissemination through social media (i.e. Facebook, Twitter, ResearchGate and LinkedIn).
• Update of the Wikipedia page on extractive metallurgy, as now the description of ionometallurgy is also included.
• Presentations of general aspects on ionometallurgy via local scientific events, such as the British Science Festival and Pint of Science, version 2022. Results of public and policy interest have been disseminated via news articles: https://www.bbc.co.uk/newsround/62886797
In addition, this new knowledge is currently being used as educational and training material within the Centre for Sustainable Material Processing and the Centre for Sustainable Resource Extraction, at the University of Leicester.
Current research has focused on the sustainable and efficient recovery of critical/technological metals from secondary raw materials by integrating the use of non-aqueous solvents, such as deep eutectic solvents (DESs) and unconventional brines, with process intensification methodologies such as ultrasound and electrocatalysis. Spent electronic components (SEC), such as printed circuit boards, solar photovoltaic (PV) cells, magnets and thermoelectrical generators, were considered as they are an attractive source for critical/technological metals. Until now, the dissolution and subsequent recovery of metals from SEC considers either pyro- and/or hydrometallurgy. Such processing routes are typically very energy intensive, and are not exempted of producing a vast amount of solid and liquid residues. Consequently, there is a need to develop more energy-efficient and environmentally-compatible processes. Deep eutectic solvents (DESs) have several advantages over traditional solvents, such as low cost and ease of preparation from readily available components. Thus, metals can be directly recovered from complex solid materials by following a similar principle to the traditional chemical processes, but with higher selectivity and lower toxicity.
The utilisation of brines, on the other hand, demonstrated promising results for leaching metals as a replacement for traditional mineral acids and/or highly viscous DESs. Due to their high water content, these liquids have a lower viscosity in comparison to ionic fluids. Hence, they represent a new medium with interesting properties for the dissolution and recovery of metals, which deserve further attention.
Within the ELECTROION project, it was pioneered the catalytic dissolution of metals from meteorite proxies of metal-rich asteroids using a DES. Three types of meteorites were investigated: 2 chondrites and one iron meteorite. Chondrites samples were composed of silicates (olivine, pyroxene, amphibole) with metallic phases occurring as native metal alloys and sulphides. Metallic Fe-Ni and troilite (FeS) were the most abundant metal-bearing phases in all three samples, particularly in the iron-rich meteorite. The samples were subjected to chemical micro-etching experiments with iodine and iron(III) chloride as oxidising agent in a DES formed from the mixture of choline chloride (ChCl) and ethylene glycol (EG). Micro-etching experiments demonstrated that iron-nickel phases were effectively leached out in this solvent, while other mineral phases remained unreactive. Thus, chemical oxidation using DESs has a great potential for metal recovery and separation from NEAs. DESs such as the eutectic system ChCl: 2EG meets some of the criteria for its potential use in space, being an anhydrous solvent and having low vapour pressure. In addition, due to the relatively high chloride concentration (ca. 5 mol dm ̶ 3) and the absence of oxygen gas in space, the formation of less reactive oxide/hydroxide is circumvented. Furthermore, the technology hereby proposed, though in a nascent stage, is very promising with DESs possessing many favourable physical and chemical characteristics. Moving forward, this will require an integrated understanding of how asteroids have been formed, what minerals host potentially useful metals, and what electrochemical methodologies can be implemented for metal recovery.
The utilisation of brines, on the other hand, demonstrated promising results for leaching metals as a replacement for traditional mineral acids and/or highly viscous DESs. Due to their high water content, these liquids have a lower viscosity in comparison to ionic fluids. Hence, they represent a new medium with interesting properties for the dissolution and recovery of metals, which deserve further attention.
Within the ELECTROION project, it was pioneered the catalytic dissolution of metals from meteorite proxies of metal-rich asteroids using a DES. Three types of meteorites were investigated: 2 chondrites and one iron meteorite. Chondrites samples were composed of silicates (olivine, pyroxene, amphibole) with metallic phases occurring as native metal alloys and sulphides. Metallic Fe-Ni and troilite (FeS) were the most abundant metal-bearing phases in all three samples, particularly in the iron-rich meteorite. The samples were subjected to chemical micro-etching experiments with iodine and iron(III) chloride as oxidising agent in a DES formed from the mixture of choline chloride (ChCl) and ethylene glycol (EG). Micro-etching experiments demonstrated that iron-nickel phases were effectively leached out in this solvent, while other mineral phases remained unreactive. Thus, chemical oxidation using DESs has a great potential for metal recovery and separation from NEAs. DESs such as the eutectic system ChCl: 2EG meets some of the criteria for its potential use in space, being an anhydrous solvent and having low vapour pressure. In addition, due to the relatively high chloride concentration (ca. 5 mol dm ̶ 3) and the absence of oxygen gas in space, the formation of less reactive oxide/hydroxide is circumvented. Furthermore, the technology hereby proposed, though in a nascent stage, is very promising with DESs possessing many favourable physical and chemical characteristics. Moving forward, this will require an integrated understanding of how asteroids have been formed, what minerals host potentially useful metals, and what electrochemical methodologies can be implemented for metal recovery.