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The European Union determines a group of elements as critical raw materials (CRM) due to their economic importance and supply risk. Lithium and a group of rare earth elements were included in the latest CRM list (2020).

The importance of these has been increased, especially related to the development of green energy technology. Lithium is needed particularly in manufacturing rechargeable batteries used in electric cars and mobile phones. Rare earth elements (REEs) are utilized in wind turbines and small amounts occur also in different household products, e.g., DVD players, smartphones, computers, and TVs.

Thus, mostly raw materials are extracted from the bedrock: more precisely from minerals and rocks that composed of them. Lithium and REEs were chosen as the scope of the study due to their topicality and analysed samples were collected from the European Union region.

Laser-spectroscopy in mineral and rock analysis

In laser-spectroscopic analysis, interaction between laser light and matter can be measured.

In the presented Ph.D. thesis, the used laser-spectroscopic methods give different kinds of information about mineral and rock samples. Laser-induced breakdown spectroscopy (LIBS) determines an elemental composition of a mineral and it is suitable for also detecting light elements. Thus, it is also very suitable for analysing lithium minerals. Molecular structures and mineralogical information can be determined with time-gated Raman spectroscopy, which is also suitable for detecting luminescent minerals. Laser-induced luminescence spectroscopy reveals the minerals’ luminescence activators occurring even in very small concentrations. Rare earth elements can commonly act as luminescence activators.

These methods are suitable for in situ and on-line analysis: Measurements are very rapid, sample preparation is minimal and, thus, analysis can be performed directly from the mineral or rock sample surface.

Partly this study is financed by the Academy of Finland, while the project of lithium-bearing rock analysis with LIBS was funded by the K. H. Renlund Foundation, that focuses on supporting geological research.

Background

Sari Romppanen graduated as Master of Science from the University of Turku in 2014 with a major subject as geology and mineralogy. Already her Master’s thesis was interdisciplinary work consisting of analysing the geochemical pathways of metals from bedrock and soil into water and berries. Before the Ph.D. project, Romppanen worked at the mining industry, and she understands the importance of the fast methods in ore analysis.

The research is published in JYU Dissertations series, number 393, Jyväskylä, 2021.
ISBN 978-951-39-8689-6 (PDF), URN:ISBN:978-951-39-8689-6, ISSN 2489-9003
Permanent link to publication:

M.Sc. Sari Romppanen defends her doctoral dissertation "Laser-spectroscopic studies of rare earth element- and lithium-bearing minerals and rocks" at the Ä¢¹½Ö±²¥ on Monday 14 of June 2021 starting at noon.  Opponent is Professor Michael Gaft (Ariel University) and Custos is University Teacher Saara Kaski  (Ä¢¹½Ö±²¥). The doctoral dissertation is held in English.

The audience can follow the dissertation online.
Link to the Zoom Webinar event (Zoom application or Google Chrome web browser recommended):

Phone number to which the audience can present possible additional questions at the end of the event (to the custos): +358 40 805 3691