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GeoNetZero Centre for Doctoral Training (CDT): Mechanistic understanding of electro-oxidation processes for the selective recovery of battery technology metals from sulfidic geological minerals Ref: 4400

About the award

GeoNetZero

The CDT led by Herriot Watt, represents an exciting partnership between the Universities of Aberdeen, Birmingham, Dundee, Durham, Exeter, Keele, Newcastle, Nottingham, Plymouth, Royal Holloway and Strathclyde, the British Geological Survey, the Natural Environment Research Council and the Ministry of Business, Energy & Industrial Strategy. Its bespoke residential training program is funded by 9 industry sponsors: BP, Cairn Energy, Chrysaor, CNOOC, Equinor, ExxonMobil, Shell, Total and Verus Petroleum.

The CDT's research focus is on tackling the challenge of sustainable resource management and the crucial role the subsurface will play in the low-carbon energy transition towards a net zero carbon economy, covering the full spectrum of topics from carbon storage and geothermal energy to sustainable oil and gas resource management. The CDT projects will be of interest to those with a background primarily in the geosciences.

The CDT's academic partners have 17 fully-funded positions PhD available to commence in early October 2020.  Studentships are for 4 years, provide funding for tuition fees and stipend at the national UK Research & Innovation (UKRI) level and a generous £5k per annum Research Training & Support Grant (RTSG) allowance.

Location: Camborne School of Mines and the Environment & Sustainability Institute, Penryn, Cornwall.

Primary Supervisor: Dr Rich Crane, Camborne School of Mines, University of Exeter.  r.crane@exeter.ac.uk

Co-supervisor: Professor Karen Hudson-Edwards, Environment & Sustainability Institute and Camborne School of Mines, University of Exeter. k.hudson-edwards@exeter.ac.uk

Project Description:

The problem:

Battery technology metals underpin almost all modern technology and humankind’s urgently
needed transition to a new Green Economy is therefore inexorably linked to their continued
procurement from both primary ores and waste. An intrinsic issue, however, is that our current
metal mining practices are deeply unsustainable.

Towards a solution:

To shift the current paradigm away from its constraints, the obvious ‘Grand Challenge’ question is:
“Can we obtain metals from their host minerals with drastically less energy input and generating
little (or even zero) waste?”

To meet this end this GeoNetZero PhD project will explore the mechanisms and kinetics of
combining a targeted electric field with a solvent to enable the selective leaching of battery
technology metals, including Cu, Ni, Zn and Co, from sulfide-bearing geological materials. Our group
has recently provided a proof of concept for this process (for the recovery of Cu from a sulfidic ore)
[1], however, research in this area remains in its infancy. This project will build on this preliminary
work in order to develop a mechanistic understanding of this new sustainable mining approach. In
particular we will target a range of minerals which are known to be conceptually amenable for
leaching, however, very little is known with regard to how they will behave when a targeted electric
field is superimposed.

References

[1] Martens E, Prommer H, Sprocati R, Sun J, Dai X, Crane R, Jamieson J, Tong PO, Rolle M, Fourie A.
Toward a more sustainable mining future with electrokinetic in situ leaching. Science Advances.
2021 Apr 1;7(18):eabf9971.

Stated link to the overarching theme of the CDT. The Role of Geoscience in the
Energy Transition and the challenge to meet the net zero emission targets:

Electrokinetic in situ leaching is a new Sustainable Mining process which has the potential to enable
the extraction of battery metals, such as Cu, Ni, Zn and Co, from the subsurface and surface
stockpiles without the need to physically excavate the material. This would enable such metal
recovery to occur with less energy requirement and environmental disturbance than conventional
practices.

>99% of all metals (by mass) are currently extracted from the subsurface via physical excavation,
which requires complete removal of overburden (and associated biological inhabitants), in order to
gain access to the target metal, which then invariably also requires removal of the gangue material
(often >99% by volume). Several hundred Gt of metalliferous mine waste are produced each year
(this is several orders of magnitude greater than the production of municipal solid waste) with
commensurate global scale ecological damage. Metal mining also remains amongst the most
significant individual contributors to the Climate Emergency via direct CO2 emissions. It is therefore
clear that a different approach is required in order to avoid a triple environmental crisis of resource
scarcity, mine waste overload and irreversible Climate Change.

Details of mapping/fieldwork locations/data to be used by the project and confirmation of access to key data being secured: 

This project will target battery metal bearing minerals which are relevant to the UK (located within both onshore and offshore metal resources) and world-wide. Samples will be procured from industry and pure ‘control’ mineral samples will be purchased from verified suppliers.

Outline of planned work schedule for the 4-year research period:

The overarching objective of this GeoNetZero PhD project is to provide a mechanistic understanding
of how EK can be applied for precise control over metal leaching and solvent movement in battery
technology metal-bearing geological minerals. Research output in this area is currently limited to
our study ([1], above) wherein we focussed on the Cu system. These preliminary results suggest that
this new Sustainable Mining process could represent a step change in our ability to leach metals
from minerals which have previously been considered inaccessible for in situ leaching due to their
exhaustively low hydraulic conductivity. Instead we propose a new approach: using a targeted
electric field to transmit the solvent via electromigration, which is known to be much more
effective at transmitting fluids through low hydraulic conductivity systems than conventional
hydraulic pumping.

Key research questions will include:

To what extent can an electric field exhibit precise control over the movement of a solvent through
a low permeability mineral and/or across preferential flow pathways? To what extent can solvents
exhibit selectivity for target metal leaching and can such activity be fine-tuned using electrokinetics?
Can hybrid techniques (such as ultrasonication) be utilised to improve electrokinetic in situ leaching
even further?

The following will be conducted:

1) Sample procurement (Months 0-6): this will involve the undertaking of a targeted literature
survey and liaising with industry in order to identify a small selection of minerals which are suitable
for electrokinetic in situ leaching (EK-ISL) but also nationally and globally relevant in terms of battery
technology metal content (minerals may include: chalcopyrite, pentlandite, erythrite and
sphalerite). Samples will undergo comprehensive analytical characterisation using a range of
techniques including: QEMSCAN, SEM-EDX, XRD, ICP-MS/OES (follow total acid digestion) and XRF.

2) Small-scale electrokinetic in situ leaching experiments (Months 6-24): this will involve the
construction (and optimisation) of small-scale (e.g. 20x20x20cm) electrokinetic in situ leaching
reactions cells (building on our published output [1]) in order to undertake a range of controlled
experiments as a function of time, solvent chemistry, electric field intensity, mineral particle size
distribution and electrode architecture. Such experiments will use real mineral samples, mixtures
of minerals and gangue material, and synthetic comparator systems (i.e. pure quartz sand mixed
with mineral-bearing particles) in order to interrogate the fundamental processes, including the
differential contributions of electromigration, electro-osmosis and electrophoresis to metal
movement. Aqueous samples will be collected in effluent chambers and then analysed using ICPMS/OES in order to understand the efficacy of the leaching process and the physical and chemical
composition of the sediment following the cessation of each experiment will be compared with the
starting material (using the analytical techniques listed in (1)) in order to understand the selectivity
of leaching and prevalence of different flow regimes (plug flow vs preferential flow).

3) Larger-scale electrokinetic in situ leaching experiments (Months 24-36): the most promising
application specifications (and associated sample types) with be further interrogated at larger scale
(e.g. 50x50x50cm) in order to gain further understanding of scale-dependent processes (such as
preferential flow, surface passivation and gangue mineral chemistry phenomena). Full analytical
characterisation (using the techniques outlined above) will be conducted.

All output will be published in Open Access academic journals.

Supervisory arrangements and involvement of external partners:

This project will foster collaborations with Professor Henning Prommer and Professor Andy Fourie (University of Western Australia) and Professor Massimo Rolle (Technical University of Denmark). This incoming GeoNetZero PhD candidate will join our growing and vibrant research team (which currently comprises 2 Postdocs and 1 PhD student). We currently undertake monthly targeted meetings in order to coordinate research activities and liaise through our “EK-ISL” TEAMs Channel. The incoming GeoNetZero PhD candidate will be encouraged to engage fully with this useful resource.

Likely graduate career routes:

This PhD project will suit those who are targeting either academic or industrial career pathways.
Electrokinetic in situ leaching remains in its infancy (it is currently at Technology Readiness Level 1-
3) and there are an entire suite of minerals (and ore deposit types) which we are yet to explore –
such minerals will be the focus on this PhD project and as such the research will be predominantly
Blue Sky but retain a long-term perspective towards commercial reality. The student will gain an
expert understanding of a wide range of disciplines and analytical protocols which span the nexus
of electrochemistry, hydrogeology and hydrometallurgy – as such the student will be well suited to
either gain Postdoctoral positions in these fields, or equally to work within R&D positions within
either start-up or large mining companies, particularly those which are engaged in in situ leaching
practices (which is an emerging area for the mining industry).

Visit the GeoNETZero CDT website for information about the partnership or contact the CDT manager, Lorna Morrow, on L.H.Morrow@hw.ac.uk

Funding

Studentships are fully funded for 4 years and cover tuition fees and stipend at the UK Research & Innovation recommended levels for each year of study.  For the 2020/21 academic session, this is £4,327 for fees and £15,609 for stipend.

Eligibility

GeoNetZero CDT studentships are open to UK and Irish nationals who, if successful in their applications, will receive a full studentship including payment of university tuition fees at the home fees rate.

A limited number of full studentships are also available to international students which are defined as EU (excluding Irish nationals), EEA, Swiss and all other non-UK nationals.  For further details please see the GeoNetZero CDT website.

Those not meeting the nationality and residency requirements to be treated as a ‘home’ student may apply for a limited number of full studentships for international students. Although international students are usually charged a higher tuition fee rate than ‘home’ students, those international students offered a GeoNetZero Centre for Doctoral Training full studentship starting in 2022 will only be charged the ‘home’ tuition fee rate (which will be covered by the studentship).

International applicants need to be aware that you will have to cover the cost of your student visa, healthcare surcharge and other costs of moving to the UK to do a PhD. More information on this is available from the following link https://www.exeter.ac.uk/students/international/applyingforavisa/studentvisas/money/.

The conditions for eligibility of home fees status are complex and you will need to seek advice if you have moved to or from the UK (or Republic of Ireland) within the past 3 years or have applied for settled status under the EU Settlement Scheme.

Entry requirements

You should have or expect to achieve at least a 2:1 Honours degree, or equivalent, in a relevant science subject.  Experience in pertinent research areas is desirable.

If English is not your first language you will need to meet the English language requirements and provide proof of proficiency.  For more information and a list of acceptable alternative tests please see http://www.exeter.ac.uk/pg-research/apply/english/http://www.exeter.ac.uk/pg-research/apply/english/

How to apply

You will be asked to submit some personal details and upload a full CV, covering letter and details of two academic referees. Your covering letter should outline your academic interests, prior research experience and reasons for wishing to undertake this project.

Please quote reference 4400 on your application and in any correspondence about this studentship.

Summary

Application deadline:18th February 2022
Number of awards:1
Value:4-year studentship: Tuition fees (UK) and an annual stipend at the national UKRI level
Duration of award:per year
Contact: PGR Admissions Team pgrenquiries@exeter.ac.uk