Contaminated Soils as Potential Secondary Sources of Critical Metals: Remediation Technologies and Recovery Perspectives

Critical metals play a crucial role in advancing sustainable energy technologies, with their demand steadily increasing due to the global push for a circular economy. At present, critical metals are primarily extracted from mineral resources, but critical metal-contaminated soils could often be considered as an alternative source of these elements. There is a growing need for remediation approaches that not only decontaminate soils but also recover valuable metals, thereby aligning with the principles of a circular economy. This review aims to suggest soil remediation strategies able to tackle critical metals contamination, particularly those capable of extracting these elements (dual-purpose technologies). Existing studies indicate that critical metal-contaminated soils are commonly found near mining sites, but their increasing use is spreading these elements into the whole environment. Considering nickel as an example of critical metal, we examine some consolidated technologies which, in addition to remediation, enable the recovery of this critical metal from the soil. Phytomining demonstrated significant potential in extracting nickel from contaminated soils. Electrokinetic treatment and soil washing can be considered as a promising methodology to clean up soils, also facilitating nickel recovery.