CMMMech
CMMMech > Element > Neodymium

Neodymium element Critical Material

The element Nd. The identifier grounds the element, not an Nd(III) ion, mineral species, magnet alloy, or discarded magnet. The US designation below concerns the named neodymium mineral commodity in the separate 2022 and 2025 lists; these dated designations do not assign criticality to every Nd-bearing resource. The mechanisms distinguish biosorption from microbial production of a lixiviant that releases Nd from a synthetic phosphate substrate.

Identifiers & Classification

System Identifier Label
CHEBI CHEBI:33372 neodymium atom

Criticality Designations

Jurisdiction List Name Edition / Document Classification Source
United States of America USGS Final List of Critical Minerals 2022; Federal Register 87:10381-10382 critical usgs2022
United States of America USGS Final List of Critical Minerals 2025; Federal Register 90:50494-50497 critical usgs2025
European Union Regulation (EU) 2024/1252, Annex II, Section 1(r), light rare earth elements (neodymium membership documented in ec2017_groups) 2024 original act; OJ L 2024/1252, 3 May 2024 critical eu2024

Microbial & Biochemical Mechanisms (2)

Nd biosorption by dried Chlorella vulgaris biomass

biosorption Microbial

Associated Organisms: Chlorella vulgaris (NCBITaxon:3077)

Inactive algal biomass removed dissolved Nd from chemically prepared magnet leachate. This is biosorption, not demonstrated metabolic uptake or microbial dissolution of magnets. Specific binding chemistry is inferred.

Experimental Context & Analytical Limits:
Laboratory batch assays used SAG 211-12, dried at 90 degrees C for 24 h. Magnets were roasted at 950 degrees C for 7 h then nitric-acid leached. At pH 5, 35 degrees C, 250 mg Nd/L and 0.5 g dry biomass/L, experimental uptake calculated from aqueous depletion was 157.40 mg/g; assays used 0.2 L, 300 rpm, 90 min and duplicates. Taxonomy is species-level; the strain is specified here. No industrial Nd recovery or purified product was demonstrated.
Curated Evidence Points:
Methods and Fig. 2 support the scoped assay. The reported competing metals were below detection after pretreatment, limiting selectivity claims for untreated waste. Table 1's 188.68 mg/g is a fitted Langmuir capacity, not measured uptake.
Results discuss possible precipitation at 50 degrees C despite other statements about its absence. High-temperature removal is therefore not assigned wholly to biosorption; model fits do not establish a unique molecular mechanism.

Gluconobacter oxydans biolixiviant releases Nd from synthetic phosphate

bioleaching Microbial

Associated Organisms: Gluconobacter oxydans (NCBITaxon:442)

Biolixiviants produced by Gluconobacter oxydans B58 and its engineered derivatives solubilized Nd from synthetic Nd-phosphate powder. Selected transposon disruption strains changed filtered-leachate Nd concentrations relative to wild-type comparators. These observations do not identify a unique non-acid lixiviant or establish a recovered Nd product.

Experimental Context & Analytical Limits:
Laboratory bench-scale validation used Mon2, a synthetic mixture of monazite-Nd and rhabdophane-Nd phases, not pure monazite or a natural ore. Living B58-derived cultures grown in yeast-peptone-mannitol medium were diluted with glucose to 20% w/v and incubated for 48 h at 30 degrees C and 200 rpm to produce biolixiviant. Mon2 was contacted at 1% pulp density for 24 h at 30 degrees C and 200 rpm. The method reports filtration after leaching through 0.45 micrometre filters, but does not specify cell removal before contact with Mon2. ICP-MS measured Nd in the filtrate. Three biological replicates were used per selected strain; wild-type, an intergenic-transposon proxy wild-type, and no-bacteria controls were prepared. Supplementary Data 4A reports final pH for the bacterial assays from 2.17 to 2.84; pH was an outcome rather than a fixed common treatment. The taxonomy identifier is species-level; B58 and its derivatives are specified by the study, not separately identified by that CURIE. The study demonstrates laboratory solubilization, not industrial operation.
Curated Evidence Points:
Results describing Mon2, Fig. 3, and Methods, Direct REE-bioleaching measurements, support the substrate, controls and Nd assay. Eight of twelve selected disruption strains increased extraction by 56-111% relative to proxy wild-type; these are relative improvements, not percentages of the substrate Nd recovered. No-bacteria controls are described in Methods but are not included in Supplementary Data 4A's 42 bacterial observations, limiting independent reconstruction of background-corrected absolute dissolution from that workbook alone.
Sheet 4A contains three observations for each of twelve selected disruption strains, WT and pWT B, with extraction, final pH and final optical density. The pWT B and delta-GO_1598 triplicates support the reported approximately 111% relative improvement. Absolute workbook extraction values are not converted to a percent yield here.
Figs. 3-5 and Discussion preserve limits on genetic and chemical causality: a GO_1096 transposon disruption strongly decreased extraction, but its clean deletion did not reproduce that effect. Nine of twelve selected mutants did not significantly change pH relative to proxy wild-type; this suggests additional contributions but does not identify a chelator, redox compound or single causal pathway. Synthetic mixed-phase results are not evidence for equivalent performance on natural monazite or Nd-bearing waste.

Sources & References

  1. kucuker2017: Kucuker et al. (2017). Biosorption of neodymium on Chlorella vulgaris in aqueous solution obtained from hard disk drive magnets. PLOS ONE 12(4):e0175255.
    https://doi.org/10.1371/journal.pone.0175255 (accessed 2026-10-06)
  2. usgs2022: USGS (2022). 2022 Final List of Critical Minerals. Federal Register 87:10381-10382, document 2022-04027.
    https://www.govinfo.gov/content/pkg/FR-2022-02-24/pdf/2022-04027.pdf (accessed 2026-10-06)
  3. chebi_neodymium: ChEBI CHEBI:33372 - neodymium atom
    https://www.ebi.ac.uk/chebi/CHEBI:33372 (accessed 2026-10-06)
  4. ncbi_chlorella: NCBI Taxonomy 3077 - Chlorella vulgaris (species)
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=3077 (accessed 2026-10-06)
  5. sag21112: SAG culture catalogue - Chlorella vulgaris SAG 211-12
    https://sagdb.uni-goettingen.de/detailedList.php?str_number=211-12 (accessed 2026-10-06)
  6. marecos2025: Marecos et al. (2025). Direct genome-scale screening of Gluconobacter oxydans B58 for rare earth element bioleaching. Communications Biology 8:682.
    https://doi.org/10.1038/s42003-025-08061-4 (accessed 2026-10-09)
  7. marecos2025_data4: Marecos et al. (2025), Supplementary Data 4. Direct bioleaching measurements for selected gene disruptions and engineered strains (sheets 4A and 4B).
    https://media.springernature.com/original/springer-static/esm/art%3A10.1038%2Fs42003-025-08061-4/MediaObjects/42003_2025_8061_MOESM6_ESM.xlsx (accessed 2026-10-09)
  8. ncbi_gluconobacter: NCBI Taxonomy 442 - Gluconobacter oxydans (species)
    https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=442&retmode=xml (accessed 2026-10-09)
  9. usgs2025: USGS (2025). Final 2025 List of Critical Minerals. Federal Register 90:50494-50497, document 2025-19813.
    https://www.govinfo.gov/content/pkg/FR-2025-11-07/html/2025-19813.htm (accessed 2026-10-09)
  10. eu2024: Regulation (EU) 2024/1252 of 11 April 2024. Original Official Journal text, 3 May 2024; Annex II, Section 1(r), light rare earth elements, page 57 of 67.
    https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=OJ:L_202401252 (accessed 2026-10-09)
  11. ec2017_groups: European Commission COM(2017) 490 final, on the 2017 list of Critical Raw Materials for the EU. Annex 1, page 4, footnote 12 explicitly includes neodymium in light rare earths. Used for group membership only.
    https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52017DC0490 (accessed 2026-10-09)

Curation History

Timestamp Curator Action Summary
2026-10-08T02:36:05Z Codex (GPT-6; Codex) provenance_adoption Appended canonical history reference and this present adoption event. Earlier scientific review artifacts remain linked in the sidecar; scientific content is unchanged and was not reassessed.
2026-10-09T04:47:52Z Codex (GPT-6; Codex) evidence_curation Added Gluconobacter bioleaching of synthetic mixed-phase Nd-phosphate and the US2025 criticality entry; preserved US2022 and existing biosorption evidence. Checked primary methods, Supplementary Data 4 and identifiers; independent scientific review is recorded separately.
2026-10-09T05:51:27Z Codex (GPT-6; Codex) criticality_extension Added the historical EU 2024 Annex II designation through its named light rare earth elements entry, with source and mapping scope documented. Preserved existing scientific evidence; independent review is separate.

Record source: data/records/neodymium.yaml