Global Research Progress and Trends on Critical Metals: A Bibliometric Analysis

In the perspective of observing the latest worldwide and European strategies toward green transition and delivering a secured access to local resources, the objective of this study was to analyze the research progress on critical materials and, more specific, critical metals and review the future research hot-topics for critical metals. Consequently, a bibliometric analysis for the assessment of the current state of the art research, future trends as well as evolution through time of the critical metals research was performed in the present work. The study included four phases of work: (i) search string selection, (ii) data collection, (iii) data processing, and (iv) data interpretation. A total of 433 publications on critical metals were collected from Scopus database between 1977 and 2023, with an increasing yearly trend and a burst in 2013. The data retrieved showed a significant increase in publications related to the topic in the last 10 years. The results show that research interest is concentrated around six critical areas: (i) bioleaching as an important process of critical metal recovery, (ii) circular economy concepts and recovery of critical metals by urban mining from e-waste, (iii) resource recovery from waste landfills as urban mines, (iv) targeted studies on various critical elements (copper, zinc, gallium, silver, lithium), (v) rare elements as industry vitamins and, (vi) coal deposits and coal ashes as an alternative source of critical metals. This analysis could provide important guidance for further directions on the development of research for recovery of critical metals.