20-40. Mineralogical controls on critical mineral distribution in ores and mine waste: Implications for mineral exploration, resource recovery, and environmental impacts

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Critical minerals are essential to the economic and national security of the United States. Increasing their domestic supply, an initiate set forth by the Presidential Executive Order 13817, necessitates evaluating potentially viable sources including identifying and developing new ore deposits, optimizing recovery efficiencies at existing operations, and locating new unconventional sources including industrial and mining wastes.  Assessing potential resources of critical mineral commodities in ore and mine waste necessities an in-depth knowledge of their mineralogical hosts and their distribution and speciation within those minerals at the atomic, crystal, and chemical levels. Additionally, the mineralogical distribution of critical minerals is an important factor when evaluating the effect of weathering at legacy mine waste sites both from reprocessing and environmental perspectives.

This Mendenhall research opportunity invites proposals on mineral chemistry, crystal chemistry, and the structural and atomic complexity of minerals that may relate to topics including understanding critical mineral enrichment during ore formation, mineralogical deportment of critical minerals during ore processing and in mine waste, advances in extraction methods for their recovery, or how critical mineral commodities behave during weathering and their ultimate fate in the environment.

The complex chemical and crystallographic properties of minerals that host critical mineral commodities necessitate the use of standard and advanced mineralogical characterization techniques that include, but are not limited to, diffraction-based techniques (X-ray, neutron, and electron backscatter), electron microscopy (scanning and transmission), Raman spectroscopy, mass spectroscopy, and synchrotron-based X-ray absorption spectroscopy, X-ray fluorescence spectroscopy, and X-ray diffraction. We seek a candidate that can utilize and apply some of these complementary characterization techniques. Ongoing and potential future research by the Geology, Energy and Minerals Science Center (GEMSC) on the lifecycles of critical minerals and mine waste as a resource utilizes these capabilities, some provided by the GEMSC and some provided through standing collaborations with external facilities. Examples of current research initiatives that warrant additional study include: 1. ore genesis studies of Zn deposits with potentially recoverable Ge that have unique sphalerite trace-element chemistry and Ge speciation (Piatak and others, 2020); 2. processes that affect Ge-enrichment in mine waste where variable co-substitution mechanisms influence Ge distribution and speciation in sphalerite and its weathering products (White and others, 2020); 3. deportment of Te during the metallurgical extraction of Cu from porphyry ores (Hayes and others 2020); and 4. evaluation of potential critical mineral, base metal and precious metal recovery from mill tailings and slag (Seal and others 2021). Another emerging research area that merits further study is the distribution, speciation, and structural state of “invisible” gold (Au), commonly lost to mine waste during the processing of ores from various deposit types including porphyry Cu systems.

To advance research in mineralogical influences of critical mineral enrichment, mineral synthesis under controlled conditions and chemical environments may be an area of complementary research. Also, the reaction of minerals during laboratory leaching tests and under various temperature regimes may be warranted to better understand weathering processes, and would be useful for developing techniques for recovery of residual valuable elements. The knowledge of mechanisms of critical mineral trace element sequestration in the weathering environment (lattice bound vs. sorption) would provide constraints on models describing the fate of critical minerals.

This research opportunity requires a proficient candidate with 1. experience in field sampling of and/or laboratory work on ore deposits and/or mine wastes, 2. analytical skills and experience in some of the standard and advanced mineralogical characterization techniques discussed above, 3. interpretive skills in mineralogy and crystal chemistry, and 4. proven ability to disseminate scientific results through oral presentations and peer-reviewed scientific publications.

Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.

References:

Hayes, S.M, Piatak, N.M., Seal, R.R. II, White, S.J.O., McAleer, R, Frenzel, M., 2020, Potential for increased recovery of tellurium and other critical elements from waste products of operating mines. Abstract volume First International Conference Mineral Resources for Future Generations, AIMS, April 2-3, 2020, Aachen, Germany.

Piatak, N.M., White, S.J.O., Hayes, S.M., Seal, R.R. II, McAleer, R.J., Green, C.J., 2020, Germanium in sphalerite from Zn-Pb deposits in the USA: Insight into ore genesis and implications for resource recovery. Abstract volume First International Conference Mineral Resources for Future Generations, AIMS, April 2-3, 2020, Aachen, Germany.

Seal, R.R., Piatak, N.M., White, S.J.O., Hayes, S.M., 2021, Mine waste as a potential source of critical minerals: The importance of understanding speciation and identifying synergies between resource recovery and environmental management; Proceedings, British Columbia Geological Survey, Geological Survey of Canada, U.S. Geological Survey, and Geoscience Australia online workshop “Critical Minerals: From Discovery to Supply Chain”, November 16-18, 2021.

White, S.J.O., Piatak, N.M., McAleer, R.J., Hayes. S.M., Seal, R.R. II, Schaider, L.A., Shine, J.P., 2020, Speciation and mineral hosts of germanium in mine wastes: Implications for recovery, Goldschmidt Conference, Honolulu, Hawaii, June 21-26, 2020.

Proposed Duty Station: Reston, Virginia

Areas of PhD: Geology, chemistry, physical science, or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet the qualifications for one of the following: Research Chemist, Research Geologist, Research Physical Scientist.

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Human Resources Office Contact: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov