Project highlights

  • Gain expertise in novel methods of processing minerals in high ionic strength media.
  • Visit industry to gain insight into current hydrometallurgical mineral processing techniques.
  • Design and build prototype reactors for processing minerals with optimal space-time yield.

Overview

The mining industry accounts for 10 percent of world energy consumption. The US mining industry alone consumes 1246 Trillion Btu/Year. Much of this is concerned with drilling, crushing and the logistics of ore movement. Traditional ore processing is generally carried out using either hydrometallurgy (high cost, low volume, reasonable selectivity) or pyrometallurgy (lower cost, high volume, low selectivity). Both methods require a large energy input and produce large volumes of waste e.g. slags or waste water. This project will seek to propose a paradigm shift in mining seeking to extract metals in situ without drilling. This will use a new type of solvent process and a novel method of fracturing rock with the aim of being more selective, using less energy, and being more environmentally compatible.

Electrocatalytic and electrolytic methods can be used to solubilize metals and metallic compounds from complex matrices. Ionic media can also increase the selectivity and efficiency of metal extraction and winning. The main issue is mass transport and rates of reaction in viscous media. This project aims to use focused ultrasound to dissolve minerals in-situ. Ultrasound has been used for assisted drilling (UAD) but never with a reactive lixiviant. Negating much of the need for drilling and moving and treating gangue material could reduce energy consumption by 80% and reduce environmental issues such as tailings dams and slag heaps.

The project will address a diverse group of ore minerals commonly encountered in important hydrothermal deposit types such as epithermal gold and porphyry copper (including the world-class Lepanto deposit, in the Philippines, with our partner ARGO). These minerals, and the chemical elements they host, pose both challenges and opportunities for mineral processing operations.

This project will explore the electrochemistry of common sulfosalt minerals in ionic liquids to assess the potential for new environmentally-benign approaches to processing. It will suit a student, either with a degree in mineral processing/applied geology/geochemistry/mineralogy who is keen to develop skills in chemistry and engineering, or with a degree in chemistry who is keen to apply their skills in the mineral processing industry.

Host

University of Leicester

Theme

  • Climate and Environmental Sustainability

Supervisors

Project investigator

  • Prof Andy Abbott

 

 

Co-investigators

  • Prof Gawen Jenkin

How to apply

Methodology

You will characterise the structure and chemistry of sulphosalt samples, assessing their reactivity in deep eutectic solvents and their reaction products using optical profiling, cyclic voltammetry, UV-vis spectroscopy, fast frame video and electrochemical quartz crystal microbalance. These data will be correlated with the mineralogical information to derive general rules about the behaviour of these minerals. These results will be used to design bulk tests on concentrated samples to assess the efficacy of dissolution and methods of recovery of the components from solution. There will be the opportunity to investigate routes to produce end-products as well as means of safe disposal of waste products (such as converting arsenic to scorodite). Based on results, a pilot scale test will be carried out to demonstrate the possible industrial application of your work. The ‘Green’ metrics of the process will be calculated to support the objectives of improving sustainability and decreasing environmental  impact.

Training and skills

Geological training will include: reflected light microscopy and scanning electron microscopy (SEM) for mineralogical and textural characterisation of sample material, operation of the electron microprobe to determine the chemistry of samples and X-ray diffraction (XRD) to confirm crystal structures. Chemical training will include: electrochemical techniques such as cyclic voltammetry and chronocoulometry, advanced microscopy including SEM and 3D optical profilometry, and spectroscopy to determine speciation in the solid and solution states.

You will have the opportunity to take introductory modules in mineralogy, ore deposit geology, Advanced Analytical Chemistry or Sustainability of Materials to upgrade your knowledge as required. We will also provide training on enterprise and protecting intellectual property.

Partners and collaboration

Prof Abbott developed deep eutectic solvents and their application to metal processing. He has worked on scale-up and chemical engineering aspects of reactor design through numerous EU and Innovate UK projects. He is a partner on a Marie Curie Training network on ionometallurgy. Prof Jenkin has over 25 years experience in mineralogy and geochemistry and their application to mineral deposits He has pioneered mineral processing with Prof Abbott over the past 5 years. If a suitable candidate is chosen we will approach ARGO to sponsor the CASE part of the project.

Further details

Prof Andrew Abbott;

Department of Chemistry, University of Leicester,

LE1 7RH, UK

T: 0116 252 2087,

E: [email protected]

To apply to this project please visit: https://le.ac.uk/study/research-degrees/funded-opportunities/centa-phd-studentships

Possible timeline

Year 1

Training in research techniques. Obtain additional samples (including museum visits) and characterise these mineralogically. Carry out experiments on selected samples to scope out the major controls on dissolution and metal recovery. Publication and presentation at national conference.

Year 2

Visit processing operations to observe current practices, obtain samples and liaise with metallurgical staff. Systematically investigate a range of samples with the aim of being able to predict reactivity across the group and write publication. Bulk testing of concentrates and investigation of recovery. Presentation at international conference.

Year 3

Completion of bulk testing and write publication. Presentation at international conference. Design and implementation of pilot demonstration. Final publication. Write and submit thesis.

Further reading

  • Abbott A. P., Frisch G., Hartley J. Ryder K. S. Processing of metals and metal oxides using ionic liquids Green Chem., 2011, 13, 471–481
  • Abbott A. P., Harris R. C., Holyoak F., Frisch G., Hartley J. Jenkin G. R. T., Electrocatalytic Recovery of Elements from Complex Mixtures using Deep Eutectic Solvents Green Chem., 2015, 17, 2172 – 2179
  • Jenkin GRT, Al-Bassam AZM, Harris RC, Abbott AP, Smith DJ, Holwell DA, Chapman RJ, Stanley CJ (2015). The application of deep eutectic solvent ionic liquids for environmentally-friendly dissolution and recovery of precious metals. Minerals Engineering, 2016, 87, 18-24
  • Abbott A. P., Al-Bassam A. Z. M., Goddard A., Harris R. C., Jenkin G. R. T., Nisbet F. J. and Wieland M., Dissolution of Pyrite and other Fe-S-As minerals using Deep Eutectic Solvents, Green Chem, 2017, 19, 2225 – 2233
  • M. Pateli, D. Thompson, S. S. M. Alabdullah, A. P. Abbott, G. R. T. Jenkin, J. M. Hartley The effect of pH and hydrogen bond donor on the dissolution of metal oxides in deep eutectic solvents, Green Chem., 2020, 22, 5476-5486
  • Lei, I. Aldous, J. M. Hartley, D. L. Thompson, S. Scott, R. Hanson, P. A. Anderson, E. Kendrick, R. Sommerville, K. S. Ryder, A. P. Abbott, Lithium ion battery recycling using high-intensity ultrasonication, Green Chem., 2021, 23, 4710 – 4715

 

COVID-19

As long as the University laboratories are open then the project should be able to continue as planned. All of the samples required have already been sourced. If there was some University closure then the techno-economic and life cycle analysis of the process, and benchmarking this against current processes, would take a larger role in the overall project. We have done this very successfully with other projects during lockdown and developed a process called retro-economic analysis which provides useful cost-benefit analysis based on a commodity price. This could account for a closure of 4 months and could enable a paper and thesis chapter to be written. A longer stoppage would lead to a desk study modelling potential new lixiviants (liquids used to digest a solute) based on their cost and environmental compatibility.