09/12/2021
Marie Skłodowska-Curie Actions

MSCA-COFUND-CLEAR-Doc - PhD Position #CD21-27 "Behavior of pyrite-rich geomaterials : experimental and thermo-hygro-chemical modelling of the oxydation effect"

This job offer has expired


  • ORGANISATION/COMPANY
    Université Gustave Eiffel
  • RESEARCH FIELD
    EngineeringMaterials engineering
  • RESEARCHER PROFILE
    First Stage Researcher (R1)
  • APPLICATION DEADLINE
    21/03/2022 17:00 - Europe/Brussels
  • LOCATION
    France › Marne-La-Vallée
  • TYPE OF CONTRACT
    Temporary
  • JOB STATUS
    Full-time
  • HOURS PER WEEK
    35
  • OFFER STARTING DATE
    03/10/2022
  • EU RESEARCH FRAMEWORK PROGRAMME
    H2020 / Marie Skłodowska-Curie Actions COFUND
  • REFERENCE NUMBER
    101034248
  • MARIE CURIE GRANT AGREEMENT NUMBER
    101034248

OFFER DESCRIPTION

Sulfur is an element present in most of geological formations, particularly in sedimentary basins. Present in the form of sulphates under gypsum CaSO4.2H2O form or sulphides under pyrite FeS2 form, only the sulphates content is usually considered in environmental regulations on excavated soils and no specifications are given on sulphide content. However, a important challenge concerns the reuse of excavated soils above all in urban areas (soil excavated during the excavation of foundations for buildings or road infrastructures or during the deeper excavation with tunneling machines).

These materials produced in very large quantities require, if they cannot be reused, to be stored on adequate sites considering their geochemical characteristics. Applied tests for soil qualification are based on short term leaching with water and they do not allow to evaluate the slow evolution of pyrites once in contact with water and oxygen (in air) as well as the effect of such oxidizing effect. Indeed, the presence of pyrites can be at the origin of pathology (swelling) when they are present in compacted soil layers under pavements or at the origin of sulphate pollution if the management of pyritic soils on storage sites is not conform (pyrites produce sulphuric acid and soluble sulphates, an acid that can be neutralized by carbonates, then producing gypsum). However, these harmful effects from an environmental and/or geotechnical point of view occur more or less quickly or even very slowly because the oxidation kinetics of pyrites is difficult to assess, given its variability according to the environmental conditions and the compaction rate of soil.

The present PhD thesis proposes both experimental and modelling work in order to better understand the harmful potential of pyrites in geomaterials (excavated soils, foundation soils, concrete sands...). This work concerns both the field of storage of excavated soil to avoid a possible pollution, earthworks for infrastructure in order to limit damages under pavements, quarries domain (pyrite-rich aggregates can be found in concrete) but also the management of mining waste that generates acid water (problem of well known acid mine drainage). It proposes to realize a critical review of the different tests (standardized or not) and approaches available in the literature to characterize the harmful potential of pyrites (review of static or dynamic test, discussion of the significance or not of threshold value to define a harmfulness)

This work plans to acquire fundamental knowledge on the phenomenon of pyrite oxidation (study of surface reactivity) leading to the drafting of recommendations for the management of pyritic soil. This work will be based on tests applied on soil layers extracted from the Paris basin (sandy and clayey layer from Ypresian geological formation). The different steps could be:

  1. Study of the parameters impacting the pyrite oxidation phenomenon (and other sulfides potentially present after quantitative mineralogical characterization and observation): batch experiment to impose an oxidation in saturated condition and study of the phenomenon at particle scale (reactivity of the pyrite surface using electrochemistry).
  2. Study of the inhibiting parameters (or protective effects against the oxidation of pyrites): a better understanding of the role of the organic matter and in particular the lignite (close to coal) present in close contact with the clusters of pyrites in some Ypresian clay formations.
  3. Study of the neutralization by carbonates of the acid generated by the pyrite oxidation: we are interested in the potential of slow-reacting carbonates such as dolomite as opposed to calcite as well as the impact of the size of the carbonate particles and the mixing method to be applied to obtain an optimum neutralization (comparison with a non-optimized mixture).
  4. Determination of the oxidation kinetics according to the environmental conditions applied with percolation column tests (experiment in saturated condition, in unsaturated condition and comparison with an oxidation under air in contact with the humidity of the air leading potentially to a phenomenon of passivation of the pyrite surface), experiment using wet/dry cycles such as proposed in the standardized dynamic procedures of characterization of pyritic materials.
  5. The challenge is to understand the relationship between the kinetics measured in laboratory tests and those observed under in situ conditions (e.g. on a pyrite soil storage site). To cover the different cases, a model of the pyrite oxidation phenomenon is proposed with a coupled Thermo-Hygro-Chemical (THC) approach
  6. Finally, the last step would be to compare the results of modelling and measurements performed on pyrite materials extracted from sites (1:1 scale) using the environmental parameters under which the material has been submitted (duration, temperature/activation of the phenomenon, rainfall/leaching...)

Finally, this PhD thesis work will provide a tool (validated model) to better understand the cycle of sulfides in the environment, particularly in relation to excavated soil. The actions of micro-organisms which also play an important role should not be forgotten and an attempt to better understand the mechanical impact (in terms of swelling) of pyrites in a compacted soil treated for example with hydraulic binder will be done.

More Information

Benefits

  • High-quality doctoral training rewarded by a PhD degree, delivered by Université Gustave Eiffel.
  • Access to cutting-edge infrastructures for research & innovation.
  • Appointment for a period of 36 months based on a salary of 2 700 € (gross salary per month).
  • Job contract under the French labour legislation in force, respecting health and safety, and social security: 35 hours per week contract, 25 days of annual leave per year.
  • International mobility will be mandatory.
  • An international environment supported by the adherence to the European Charter & Code.
  • Access to dedicated CLEAR-Doc trainings with a strong interdisciplinary focus, together with a Career development Plan.

Eligibility criteria

  • At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree. At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate.
  • At the time of the deadline, applicants must be in the first four years (full-time equivalent research experience) of their research career (career breaks excluded) and not yet been awarded a doctoral degree. Career breaks refer to periods of time where the candidate was not active in research, regardless of his/her employment status (sick leave, maternity leave etc). Short stays such as holidays and/or compulsory national service are not taken into account.
  • At the time of the deadline, applicants must not have resided or carried out their main activity (work, studies, etc.) in France for more than 12 months in the 3 years immediately prior to the call deadline.
  • Applicants must be available to start the programme on schedule (around 1st October 2022).

Selection process

Additional comments

  • The First step before applying is contacting the PhD supervisor. You will not be able to apply without an acceptation letter from the PhD supervisor.
  • Please contact the PhD supervisor for any additional detail on job offer.
  • There are no restrictions concerning the age, gender or nationality of the candidates. Applicants with career breaks or variations in the chronological sequence of their career, with mobility experience or with interdisciplinary background or private sector experience are welcome to apply.

Web site for additional job details

Offer Requirements

  • REQUIRED EDUCATION LEVEL
    Engineering: Master Degree or equivalent
  • REQUIRED LANGUAGES
    ENGLISH: Good

Skills/Qualifications

  • At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree.
  • At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate.

Specific Requirements

International Mobility:

To be discussed with the PhD thesis supervisor.

Work location(s)
1 position(s) available at
Université Gustave Eiffel
France
Marne-La-Vallée
77454
5, Boulevard Descartes

EURAXESS offer ID: 717610

Disclaimer:

The responsibility for the jobs published on this website, including the job description, lies entirely with the publishing institutions. The application is handled uniquely by the employer, who is also fully responsible for the recruitment and selection processes.

 

Please contact support@euraxess.org if you wish to download all jobs in XML.