Description and Documentation
A greater variety of metals have an increasing importance for human development. Other than the most common metallic elements (Fe, Cr, Ni, Mn), base (Cu, Zn, Pb), light (Al) and precious metals, modern technology relies on virtually all of the stable elements of the periodic table. Consequently, there is a growing global concern over the long term availability of secure and adequate supplies of the metals needed by contemporary society. CMs, which are those of increasing economic
importance that might be susceptible to future scarcity, are a particular worry being vulnerable to politically or economically driven fluctuations in their supply.
As global demand for CMs grows, primary raw materials will continue to play a key role and mobilizing Europe domestic potential better is an essential part of the EU becoming more resilient and developing open strategic autonomy. Europe has a long tradition of mining and extractive activities and is well-endowed with aggregates and industrial minerals as well as certain base metals such as copper and zinc. It is less successful in developing projects to source critical raw materials, although there is significant potential for these (Critical Raw Materials Resilience: Charting a Path towards greater Security and Sustainability European Union report on critical raw materials, 2023).
The latter European Union report on CRMs listed many CMs and their possible sources. Notwithstanding the key role of CMs for high-technology, “low-carbon energy” industries, green and defense and space applications, for many of these metals there is not enough information on how they are concentrated in the Earth’s crust, how to extract them from their ores, and how to use, recycle and dispose them effectively and safely.
The CMs are often “co-elements”, related to the production of metals of much larger distribution and use, such as Al, Pb, Zn and Cu. For instance, REEs, Sc, Ga, and Ta have small geological resources relative to their current demand and are mainly recovered as by-products of other metallic ores. The request for CMs for the development of future technologies is thus rising enormously. Also the recycling of the technological devices derived from these metals is extremely important, as shown by the growing interest in the field of the so-called “e-waste” and “urban mining”.
For all these reasons, the interest in the scientific community to research new resources of CMs is growing hugely. The bauxite ores are commonly exploited worldwide for Al but also contain other metals of potential economic interest that are not recovered because their amounts and behavior are not completely known, and appropriate and economic metallurgical techniques have not been developed so far.
Recently, an evaluation of the critical raw materials distribution in the Sardinian bauxite, coupled with the “economic importance” and “supply risk” parameters, indicates that the ore contains large amounts of metals characterized by a “supply risk”, such as light and heavy REEs, and metals of “economic importance”, such as V and W thus suggesting Sardinian bauxite deposits can be reconsidered as a potential source of critical raw materials.
In recent years the RM were found to contain many useful metals including REEs, Sc, and Ga. However, very little data is known for RM from the Italian waste site (Portovesme storage site, SW Sardinia). On the other hand, RM, as well as mine wastes, represent nowadays a serious environmental hazard, either when stored in open tailings (e.g. the Ajka alumina plant disaster in Hungary) or when discarded in the sea, as in many cases in Europe.
The present project is thus based on three main objectives summarized below:
1. Analyzing and modeling the geochemical processes promoting the concentration of CMs in specific phases in the selected bauxite and RM samples.
2. CMs recovery from ores and RM leached solutions, mostly based on the low cost SPE methods using novel sorbents based on peptides from enzymatic hydrolysis of agricultural wastes.
3. Testing the possibility to reuse RM and bauxite residues obtained from the CMs recovery processing in new formulations of AAMs for the production of low cost and environment friendly building materials.