Sustainable Valorization of Industrial Mineral Residues: Comprehensive Characterization and Advanced Material Applications
The Industrial Chemistry Laboratory has developed a unique method for the production of dicarboxylic acids directly from oil shale, without the need for pyrolysis or combustion, thereby offering a way of security of supply of basic chemicals. In addition to dicarboxylic acids, the process also generates other organic acids and mineral by-products, all of which have potential for further valorization. Although there are several known applications for these versatile compounds, new fields need to be investigated to maximize their potential and further expand their use.
It is also important to emphasize that working with these materials is not limited to the direct conversion of oil shale — on the contrary, we believe the knowledge generated around both dicarboxylic acids and mineral residues has wide relevance, ex. from lignite (brown coal) to lignin processing residues, both of which involve the handling of hundreds of millions of tons of material globally. The goal of the project is to refine various mineral resources and mining residues that remain after the removal of organic fractions for various high-tech applications. These materials might possibly still contain some organic material which can be successfully utilized. The research can be split into two, depending on whether the focus will be set on the organic components or inorganic materials combined with materials science.
The first goal focuses on the analysis of the mineral parts that remain after the removal of organic matter. These inorganic materials need to be physicochemically thoroughly characterized (chemical composition, physical properties) to assess their feasibility in/as, e.g., catalysis, energy storage and construction materials. The potential use of light modification or treatment methods will be investigated, and their suitability will be assessed by determining whether the applicability was enhanced and to which extent. The advanced materials characterization will be carried out during the planned secondment at the University of Eastern Finland, at the laboratory of the distinguished professor Vesa-Pekka Lehto. This offers another perspective into the research thanks to the use of different analytical methods, and the international experience obtained will be highly useful.
The second goal is to convert compounds derived from organic matter into plasticizers. By transforming diacids into mono- or polymeric plasticizers, their properties can be improved and applications broadened — from defense to consumer plastics. A key innovation is the integration of inorganic residues from the same process (or other industry waste, like oil shale ash) as catalysts or fillers. Modified oil shale ash has already been successfully used in derivatization reactions (such as transesterification) and helps in reducing reliance on virgin mineral resources. Therefore, the focus of the second goal will be on developing new plasticizers, binders, and material systems by adapting the production process such as testing diacid mixtures with novel catalysts. Strong emphasis will be also placed on product composition and performance analysis.
The candidate can decide whether they are interested in both goals or would prefer to focus primarily on one, while actively collaborating with other ongoing research directions in the lab. He/she is expected to describe their preference in the motivational letter, along with some general ideas on how they would approach the topic.
This project can be considered as a combination of organic synthesis, analytical chemistry, materials characterization, it also includes development and requires an in-depth analysis of the properties of the resulting material to determine their applicability in a wide variety of applications. The ultimate aim is to create materials that match or exceed current standards, while leveraging local raw materials and integrated process design.
Dr. Birgit Mets (ORCID ID: 0000-0002-4641-1484) defended her PhD in the field of thermal engineering, on the topic of the pyrolysis of Estonian oil shale. Afterwards she shifted her focus from the pyrolysis process to valorization, with the goal of finding alternative and more useful ways for the utilization of fossil fuels (instead of pyrolysis and combustion) and from technical to chemical aspects. She has been a member of the (senior) research staff of numerous projects – in the last 10 years, she has participated in more than 20 projects, most of which have been dealing with oil shale and its applications in Estonia (both scientific as well as contracted research concerning industry). Four projects are currently ongoing, and these are all related to the valorisation of different resources and focus on sustainable solutions and circular economy, since her background is in the field of chemistry. She is currently working part-time at the Geological Survey of Estonia, as a technology expert, investigating the valorization potential of phosphate ores. She is currently supervising one PhD student.
Current research focus: oil shale, valorization, chemical production, material science, plasticizers.
Number of Publications: 38 (Scopus)
Key Funding:
• TK228U4, Centre of Excellence in Circular Economy for Strategic Mineral and Carbon Resources
• TEM-TA128, Sustainable Conversion of the Organic Part of Mineral Resources and Secondary Raw Materials to High Value Chemicals
• MNKE23052, Valorisation of oil shale ash into biodegradable chloride-free snow and de-icing agents
Awards and memberships:
• 2024 - ICTAC Promising Researcher Award
• 2023 - TalTech 2022 Junior Researcher of the Year
• Founder of the Estonian Thermal Analysis and Calorimetry Society (2024)
Professor Vesa-Pekka Lehto (ORCID ID: 0000-0001-8153-1070) has served as a full professor of materials physics at the University of Eastern Finland (UEF) since 2008. His research focuses on the development of silicon-based nanostructured materials for three key applications: (i) multifunctional drug delivery systems, (ii) anode materials for lithium-ion batteries, and (iii) adsorbents for metal ions, particularly in dilute aqueous solutions. He has a strong background in the physicochemical characterization of inorganic nanomaterials, pharmaceuticals, and disordered materials. He leads the Pharmaceutical Physics Research Group, comprising approximately 20 researchers in the Department of Technical Physics at UEF.
Professor Lehto has authored over 230 peer-reviewed publications. His work has been cited more than 8 000 times, with an H-index of 49 (Web of Science).
Dr. Kristiina Kaldas (ORCID ID: 0000-0002-8697-0627) is the head of the Industrial Chemistry Laboratory. She defended her PhD on the topic of the oxidation of oil shale, with the goal of producing dicarboxylic acids. Her background is in chemistry, mainly organic chemistry and synthesis. She has been responsible for the development and sustainability of the laboratory, the focus of which has been on solving chemical and chemical engineering problems for industrial companies. The work of Dr. Kaldas has been leading the paradigm shift in the use of oil shale – its direct conversion into valuable chemicals. At the same time, valorization methods for the produced residues and by-products are being developed to enhance sustainability and adhere to circular economy principles. Dr. Kaldas is the principal investigator of two out of four of her ongoing projects and is currently supervising three PhD students.
A successful candidate is expected to have a background in chemistry – experience in organic synthesis and material science are prerequisites, with knowledge about natural resources and raw materials being crucial as well. Additionally, experience in analytical chemistry (the use of different methods) is needed to be able to investigate the structure and properties of the materials obtained. The candidate must have at least 4 years of experience working in a research laboratory dealing with similar topics. Beneficial features include willingness to learn, independence, good teamwork skills, curiosity and high analytical abilities.