HISTORIC TAILINGS FROM CANANEA, MEXICO, AS A SOURCE OF CRITICAL METALS: SIGNIFICANCE OF CHARACTERIZATION AND HOST MINERAL DETERMINATION IN ASSESSING THEIR POTENTIAL

The 21st century presents a growing demand for substantial volumes of raw materials to support the development of cleaner technologies and sustainable energy sources. Consequently, there is a particular focus on critical elements, which each country identifies based on its national strategies. Exploring non-conventional sources becomes essential to secure the necessary supply of these critical elements. Many of these elements are found as trace impurities in host minerals, necessitating a comprehensive study of their occurrence and relationships as the initial step toward recovery.

Porphyry copper deposits generate large volumes of tailings, representing a potential source of elements being discarded. Cananea, Sonora is the most important copper mine in Mexico, which has a long history; as a result, some tailings were dumped more than 50 years ago, which leads us to think that there are economically attractive concentrations of elements present that were not attractive at the time, in addition to the fact that technologies have advanced. This research seeks to determine the potential of the historic tailings of Cananea Sonora as a source of critical elements through a physical, geochemical, and mineralogical characterization, emphasizing the importance of mineralogy for its assessment.

A representative surface and subsurface sampling was carried out, followed by a characterization of physical and chemical properties. The total geochemistry was determined by ICP/OES, while mineralogy was assessed using XRD. Elemental mapping was performed with EMPA-EDS/WDS.

According to the results, Cu, Ga, Mo, and Re show enrichments, considered critical for North American countries and economically attractive prospects. Their mineralogy shows that Re occurs together with Zn and S; Cu is associated with S and, in some cases, Fe. The presence of jarosite, clays, and iron oxides, which, according to the pH with an average mean of 3.6, can be the host minerals containing Mo and Re. Based on the qualitative findings, more specific and appropriate metallurgical tests can be conducted to recover these critical elements. This marks a crucial step in understanding non-conventional sources for element recovery, paving the way for more sustainable resource management.