Hyperaccumulator plants extract rare earth elements from soils, enabling low-carbon recovery through phytomining. This approach supports sustainable resource extraction and converts waste sites into productive material sources.
Study: Phytomining of rare earth elements from soils using plants. Image Credit: Rebel Red Runner/Shutterstock
In a recent article published in the journal Communications Earth & Environment, researchers explored the use of hyperaccumulator plants for phytomining rare-earth elements (REEs) from soils as a sustainable alternative to traditional mining, proposing strategies to enhance extraction efficiency and commercial viability by upcycling biomass into functional materials.
Context and Challenges of REE Phytomining
Rare earth elements (REEs) are essential components for modern technology, particularly in applications such as high-strength magnets, catalysts, LED screens, and specialty fertilizers. The global demand for REEs has surged due to their critical role in advancing low-carbon technologies, with projections indicating a doubling of demand for magnet-related REEs by 2050.
Soils worldwide contain REEs at relatively consistent concentrations, comparable to those of other metals such as copper and zinc, making them an unconventional yet potentially vast resource. In particular, soils derived from granitic weathering display elevated REE concentrations, yet these elements are often present in very dilute form and mixed with chemically similar impurities, complicating extraction by traditional methods.
Secondary sources, such as mine tailings and industrial residues, pose similar difficulties for REE recovery. Phytomining, which utilizes hyperaccumulator plants to extract metals from soils into biomass, emerges as a promising sustainable technology. This approach is suited to REE-enriched soils, including mine tailings and contaminated sites, and could turn these underutilized resources into economically viable sources of REEs with lower environmental impact.
Recovery Techniques and Biomass Processing
This study employed a multidisciplinary approach to advance phytomining of rare earth elements (REEs) from soils using hyperaccumulator plants. The first step involved selecting appropriate metal crops, plants capable of accumulating over 0.1 wt% REEs in their biomass. Candidate species include tropical and subtropical ferns like Dicranopteris linearis and Blechnopsis orientalis, as well as the temperate forb Phytolacca americana, chosen for their high biomass production and strong REE uptake.
Soil and plant REE concentrations across multiple sites were systematically analyzed to establish uptake efficiency and correlations. Post-harvest, the biomass was processed to recover REEs selectively. Hydrometallurgical techniques such as acid leaching, impurity separation, precipitation with oxalic acid, and calcination were used to produce rare-earth oxides. To address the economic and environmental challenges of this method, alternative pathways were explored.
These include direct conversion of REE-enriched biomass into functional materials like specialty fertilizers and catalysts, leveraging inherent biomass composition rich in metals such as nickel and manganese.
Environmental and economic evaluations were integrated through life-cycle assessments that compared phytomining with conventional mining. This framework combines plant biology, chemistry, and engineering to optimize phytoextraction and biomass valorization, with the aim of developing sustainable and commercially viable routes for REE recovery from unconventional sources.
Phytomining Performance and Environmental Assessment
The study identifies Dicranopteris linearis and Phytolacca americana as effective hyperaccumulators for phytomining rare earth elements (REEs) from soils. Both species exhibit significant positive correlations between soil REE concentrations and biomass accumulation, with D. linearis mainly accumulating light REEs (LREEs) in tropical and subtropical regions, and P. americana preferentially accumulating heavy REEs (HREEs) in temperate areas.
These complementary accumulation patterns suggest strategic selection of REE crops based on location and target REEs. Hydrometallurgical recovery methods applied to biomass demonstrated the ability to achieve high-purity rare-earth oxides (REOs) with recovery efficiencies approaching
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89%. However, the energy-intensive and solvent-demanding nature of these processes poses economic and environmental challenges.
Alternative approaches focus on direct conversion of REE-rich biomass into functional materials, such as specialty fertilizers and catalysts, which adds economic value and reduces carbon emissions. Ash derived from D. linearis biomass, for example, enhances crop growth and stress resistance, though environmental safety concerns related to REE exposure warrant careful assessment.
Life cycle assessment reveals that conventional mining yields higher carbon emissions compared to phytomining, which can approach carbon neutrality when plant-based CO2 sequestration is considered. Direct conversion routes further reduce environmental footprints and operational costs, increasing commercial viability.
While phytomining alone may not replace conventional mining, integrating it with existing land uses and mining rehabilitation offers sustainable avenues for REE extraction. Future research should prioritize field validation, cultivar development, and international collaboration to facilitate practical application.
Outlook and Integration Strategies
Phytomining represents a novel complementary pathway to supplement traditional REE mining by harnessing unconventional resources such as REE-enriched soils and mine wastes. While it is unlikely to replace conventional mining entirely, phytomining can reduce environmental damage and improve resource circularity by converting waste sites into productive sources.
The most immediate barriers remain low REE concentrations in biomass and the lack of cost-effective recovery methods, necessitating multidisciplinary efforts, including field trials and breeding programs, to optimize metal crops. Socio-economic benefits may emerge when phytomining is incorporated into local value chains, particularly in areas where mining has caused land degradation.
Environmental risks associated with co-accumulated toxic elements require careful management. Overall, phytomining offers a low-carbon and potentially sustainable alternative to conventional mining and, with support from international cooperative frameworks and further development, could play a significant role in future REE supply chains.
Journal Reference
Huang C. L., Xie C. D., et al. (2026). Phytomining of rare earth elements from soils using plants. Communications Earth & Environment. DOI: 10.1038/s43247-026-03549-1, https://www.nature.com/articles/s43247-026-03549-1