Selective Recovery of Critical Raw Materials by Using Metal-Organic Framework Based Adsorbents

Project Information

RUMBA

Grant agreement ID: 101024565

DOI

10.3030/101024565

Project terminated on 16 April 2023

EC signature date 23 April 2021

Start date 1 May 2022

End date 31 May 2025

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 259 398,72

EU contribution

€ 259 398,72

Coordinated by

FUNDACION ICAMCYL
Spain

Periodic Reporting for period 1 - RUMBA (Selective Recovery of Critical Raw Materials by Using Metal-Organic Framework Based Adsorbents)

Reporting period: 2022-05-01 to 2025-04-30

Summary of the context and overall objectives of the project

European industrial and technological growth strongly depends on its access to critical raw materials (CRMs) which are crucial for the development of cutting-edge technology products, such as miniaturized electronic devices, electric cars, solar cells, wind turbines, Li-ion batteries, etc.
To secure a sustainable supply of CRMs that accompany the technological growth, Europe needs to face with several challenges along the whole raw materials value chain: exploration, extraction, processing, and recycling. Regarding the ore extraction and processing methodologies, and in congruence with the Circular Economy initiative, one of the alternatives for Europe is to develop innovative methods for the recovery of the CRMs wasted as by-products in mining debris (low-grade ore deposits).

RUMBA project was designed for the tailored recovery of CRMs (Nb, Ta, W) from European underexploited mining side streams, by using Metal-Organic Framework (MOF) adsorbents. The project was conceived as a methodological improvement of the currently existing recovery processes, mainly based on liquid-liquid extraction. MOFs were selected as CRM-capturing agents due to their porosity, flexibility, adsorption capacity, chemical and thermal stability, which make them capable of extremely fast sorption with unprecedentedly high selectivity toward targeted ionic species.

The main objective of RUMBA was to provide a new route to selectively recover W, Nb, and Ta CRMs from low-grade ores by using MOFs adsorbents, opening new ways for mining and raw materials exploration, processing, and recovery.
Selected MOFs were expected to be stable, efficient, selective, with high adsorption rates, and recyclable.

RUMBA specific objectives (SO) were:

• SO1. To identify MOFs for W, Nb and Ta ion adsorption.
• SO2. To select the greener synthetic methods for the preparation of MOFs avoiding using toxic substances to the environment.
• SO3. To characterize the obtained MOFs
• SO4. To study the adsorption efficiency and selectivity of MOFs toward the target CRMs in laboratory tests and from real samples obtained from industrial low-grade ore resources.
• SO5. To exploit the interest of the CRM-MOF systems in applications of environmental relevance.

RUMBA was designed for a 36-month period, the work covered in this final report includes the first 11 months of the project.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the lifetime of the project (11 out of 36 months), a family of MOFs (known as MOF-74 or CPO-27) was identified as potential adsorbent for tungsten (W) polyoxometalates under acidic conditions (SO1)

Different synthetic approaches (solvothermal, slow diffusion, direct mixing at room temperature) were carried out for the preparation of the identified family of MOFs. Successful results were obtained for zinc and magnesium MOFs, even at room temperature and using water as solvent (SO2)
The structure and thermal stability of prepared MOFs were characterized by powder x-ray diffraction (PXRD) and thermogravimetric analysis (ATG) respectively (SO3).

In this period, the adsorption efficiency and selectivity of MOFs toward the target CRMs (SO4) was not tested, and the exploitation of CRM-MOF systems (SO5) was not explored.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

New and clean technologies demand increasing amounts of critical raw materials. In the current scenario, we are facing the major transition towards energy production through renewables and the challenge for renewable energy storage. Raw materials constitute the basis of the active components (magnets, electronics, surface) of solar panels, wind turbines, batteries, and so on. A real decarbonization of society to combat climate change goes to a secure supply of critical raw materials whose demand will grow substantially.

However, the extraction of these CRMs has often severe social and ecological consequences. For instance, mining activities can alter landscapes and ecosystems producing local contamination of water, soil, and air.

Among the strategies across the value chain to secure raw material supply, attempts towards a circular economy play a crucial role. In this regard, RUMBA involved the first approach of recovering critical raw materials from aqueous solutions by using tailored Metal-organic Framework adsorbents. A further development of such technology will allow the transformation and improvement of the current extraction/purification hydrometallurgical methods, contributing to securing the supply of critical raw materials.

Structure of the porous MOF-74 (left) and the ɑ-Keggin anion of tungsten (right)