Evidence of rare earth elements origin in acid mine drainage from the Iberian Pyrite Belt (SW Spain)

León, Rafael; Macías, Francisco; Cánovas, Carlos Ruiz; Millán-Becerro, Ricardo; Pérez‐López, Rafael; Ayora, Carlos; Nieto, José Miguel

doi:10.1016/j.oregeorev.2023.105336

Cited by 12 publications

(9 citation statements)

References 69 publications

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“…REE speciation in AMD is controlled by pH, where they predominantly occur as a mixture of free ions and sulfate complexes at low pH. , However, their concentration decreases with increasing pH due to adsorption onto particulate matter and coprecipitation with Al and/or Fe at circumneutral to alkaline pH values. , Clay minerals, specifically illite and kaolinite, comprise an appreciable component of the sediment in the Huelva estuary of the Tinto and Odiel rivers and are an important control on REE transport . Moreover, normalized REE patterns between the waters and rocks in the Iberian Pyrite Belt demonstrate a geochemical relationship between AMD and shales …”

Section: Resultsmentioning

confidence: 99%

“…The higher REE concentrations in brines also corresponded with shales and mudstones having the highest REE concentrations in the Western Canada Sedimentary Basin . This relationship could indicate water-rock interactions with fine-grained materials being the main source of REE in the brines, which is supported by leaching experiments from rocks of the Iberian Pyrite Belt, where REE normalization patterns were transferred from rocks into solution, indicating water-rock interactions as an important source of REE to the waters . However, determining the source of the REE could be considerably more complicated.…”

Section: Resultsmentioning

confidence: 99%

“…93 Moreover, normalized REE patterns between the waters and rocks in the Iberian Pyrite Belt demonstrate a geochemical relationship between AMD and shales. 21 Groundwater and basinal brines produced as a byproduct of geothermal energy production or hydrocarbon extraction have also been touted as possible REE sources. Although these waters have received less attention than AMD, the mechanisms controlling REE concentrations are similar, being strongly dependent on pH, ionic strength, and the presence of competing anions and cations in addition to fluid temperature.…”

Section: Role Of Clays In Alternative Sources Of Reementioning

confidence: 99%

“…23 This relationship could indicate water-rock interactions with fine-grained materials being the main source of REE in the brines, which is supported by leaching experiments from rocks of the Iberian Pyrite Belt, where REE normalization patterns were transferred from rocks into solution, indicating water-rock interactions as an important source of REE to the waters. 21 However, determining the source of the REE could be considerably more complicated. Quillinan et al 8 observed that while lithology is important, basinal controls and geologic history also play an important role in determining brine REE concentrations.…”

Section: Role Of Clays In Alternative Sources Of Reementioning

confidence: 99%

“…A common factor among these sources is the association of REE with clay minerals and fine-grained sediments. For example, the shales of the Iberian Pyrite Belt could be a significant source of REE to AMD waters, where their transport at neutral to basic pH conditions is dominated by particulate phases including clays . Analysis of a global data set of REE in sedimentary strata revealed that fine-grained clastic rocks are more enriched in REE than carbonates, evaporites, and sandstones, while REE concentrations in formation waters of Saskatchewan, Canada were highest in formations predominantly composed of fine-grained clastics .…”

Section: Introductionmentioning

confidence: 99%

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Rare Earth Element Adsorption to Clay Minerals: Mechanistic Insights and Implications for Recovery from Secondary Sources

Bishop,

Alam,

Flynn

et al. 2024

Environ. Sci. Technol.

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The energy transition will have significant mineral demands and there is growing interest in recovering critical metals, including rare earth elements (REE), from secondary sources in aqueous and sedimentary environments. However, the role of clays in REE transport and deposition in these settings remains understudied. This work investigated REE adsorption to the clay minerals illite and kaolinite through pH adsorption experiments and extended X-ray absorption fine structure (EXAFS). Clay type, pH, and ionic strength (IS) affected adsorption, with decreased adsorption under acidic pH and elevated IS. Illite had a higher adsorption capacity than kaolinite; however, >95% adsorption was achieved at pH ∼7.5 regardless of IS or clay. These results were used to develop a surface complexation model with the derived binding constants used to predict REE speciation in the presence of competing sorbents. This demonstrated that clays become increasingly important as pH increases, and EXAFS modeling showed that REE can exist as both inner-and outer-sphere complexes. Together, this indicated that clays can be an important control on the transport and enrichment of REE in sedimentary systems. These findings can be applied to identify settings to target for resource extraction or to predict REE transport and fate as a contaminant.

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