CMMMech
CMMMech > Primary resource > Carbonatite-associated rare-earth ore

Carbonatite-associated rare-earth ore primary resource

Naturally occurring, mixed rare-earth-bearing ore associated with alkaline-carbonatite deposits, anchored here to the tested Mushgia Khudag material from Mongolia. The deposit association does not establish that every sampled rock meets a modal carbonatite classification. The curated feed contains quartz, apatite, calcite and other phases, with monazite and parisite assignments; it is neither a pure mineral nor a processed waste. Laboratory culture pretreatment followed by sulfuric-acid leaching is represented as a treatment-associated observation with unresolved causal controls. Neither industrial deployment nor inherited criticality is asserted.

Microbial & Biochemical Mechanisms (1)

Culture-pretreatment-associated increase in subsequent acid leaching

bioleaching Microbial

Associated Organisms: Thiobacillus denitrificans (NCBITaxon:36861), Bacillus cereus (NCBITaxon:1396)

A source-labelled Tmix culture pretreatment was followed by higher dissolved rare-earth signals during subsequent sulfuric-acid treatment than direct acid leaching of untreated ore. The experiment included microbial cultures, but no matched sterile-medium pretreatment isolates their contribution from acidic, iron- and sulfate-bearing medium chemistry. Mineral and surface changes were observed; cooperative microbial action, organic-acid production and the precise dissolution pathway remain hypotheses. The final acid-leaching stage is chemical, not demonstrated microbial recovery of a separated product.

Experimental Context & Analytical Limits:
Section 2.1.1 sampled the Mushgia Khudag deposit in Tsogt-Ovoo soum, Omnogovi province, Mongolia; ore was crushed below 12.5 mm and ground below 0.074 mm. Section 2.1.2 reports Tmix grown in 9K medium from chalcopyrite-ore isolates and names the two sequence accessions above. ENA labels those sequences as strains 2mn and 1mn; their presence does not establish exhaustive community composition or separate causal roles. A separate ore-derived, source-labelled Bacillus sp. culture in NBRIP medium was also tested. Its printed identifier 4TH0UUSC016 could not be resolved and is not mapped to either Tmix member. Section 2.1.3 used 40 g ore with 80 mL of each culture in separate 250 mL flasks, 30 degrees C, 200 rpm for 7 days. Solids were filtered, rinsed twice and dried at 60 degrees C before 1.0 M sulfuric-acid leaching at solid/liquid ratio 1:6, 30 degrees C, 200 rpm for 20 h. Experiments were duplicates with standard deviations reported. ICP-OES measured total-element leachate concentrations; XRD, FTIR, pH, ORP and zeta potential characterized associated changes. No purified REE product was isolated.
Curated Evidence Points:
Sections 2.1.1-2.2.4 and 3.1-3.3, Tables 1-2 and Figures 2-8 support the mixed-ore identity and treatment-associated observation. Figure 3 labels TREE leaching as 27.29% for acid alone, 38.74% for Tmix plus acid and 29.09% for the separate Bacillus-labelled culture plus acid, versus 2.40% and 0.003% for the respective culture-only contacts. These are the article's reported solution-based extraction percentages, not independently reconciled whole-process yields or isolated-product recovery. Weak culture-only release is preserved; the abstract's implication of no direct REE dissolution is too broad.
Methods do not specify a matched sterile 9K/NBRIP pretreatment or a killed-cell control. They do not present a complete balance across pretreatment liquid, rinses, dried residue and acid leachate; the percentage equation uses initial ore mass without fully resolving interstage losses. Figure 5's initial pretreatment pH values do not match the later prose values of 1.6 and 4.0, so neither pair is promoted to a resolved initial-pH condition. The separate culture's Gram-negative description and unresolved printed identifier further limit its taxonomy. No measured organic-acid profile, oxygen uptake or direct cell-mineral localization establishes the proposed mechanism. Zeta potential was measured in filtered suspensions, not as a direct assay of mineral-specific attachment or metabolism. Reduced acid consumption, environmental benefit and industrial feasibility are not demonstrated by these batch measurements.
The exact accession cited for Tmix resolves to the deposited Thiobacillus denitrificans strain 2mn partial 16S sequence and taxon cross-reference 36861; this is sequence provenance, not experimental proof of the member's metabolic contribution.
The exact accession cited for Tmix resolves to the deposited Bacillus cereus strain 1mn partial 16S sequence and taxon cross-reference 1396. It does not resolve the separate Bacillus-labelled NBRIP culture or demonstrate strain purity.
Sections 2.1-2.3 and 3.1-3.2, Tables 1-2 and Figures 2-6 of the publisher-linked manuscript compare Mushgia Khudag and Lugiin Gol ores with the same Tmix accessions but different particle-size and loading conditions. Reported ore chemistry also differs. Shared investigators, culture accessions and sites prevent treating this as independent replication; no sample-lot equivalence is proven. Its culture comparisons and particle-size trends are not transferred into the RSC pretreatment assay, and they do not supply its missing sterile-medium control or validate a universal microbial advantage.

Sources & References

  1. bayarsaikhan2025: Bayarsaikhan et al. (2025). Enhanced recovery of rare earth elements from carbonatite ore by biological pretreatment. RSC Advances 15:4628-4635. DOI 10.1039/D4RA07845D; Sections 2.1.1-2.2.4 and 3.1-3.3, Tables 1-2 and Figures 1-8. Full PMC XML and original figure assets inspected; publisher PDF access was unavailable.
    https://doi.org/10.1039/D4RA07845D (accessed 2026-10-15)
  2. pmc11811698: PMC11811698 full-text deposit of Bayarsaikhan et al., PMID 39935465; published 11 February 2025, collection dated 6 February 2025. Same primary experiment as the RSC article.
    https://www.ebi.ac.uk/europepmc/webservices/rest/PMC11811698/fullTextXML (accessed 2026-10-15)
  3. thiobacillus_sequence: ENA/INSDC OR053813.1: Thiobacillus denitrificans strain 2mn, partial 16S ribosomal RNA gene, 1254 bases; version 1, created 14 June 2023 and updated 15 June 2023.
    https://www.ebi.ac.uk/ena/browser/view/OR053813.1 (accessed 2026-10-15)
  4. bacillus_sequence: ENA/INSDC OR053804.1: Bacillus cereus strain 1mn, partial 16S ribosomal RNA gene, 1381 bases; version 1, created 14 June 2023 and updated 15 June 2023.
    https://www.ebi.ac.uk/ena/browser/view/OR053804.1 (accessed 2026-10-15)
  5. ncbi_taxonomy: NCBI Taxonomy 36861 Thiobacillus denitrificans and 1396 Bacillus cereus, both species-rank entries; these do not identify strains or prove individual contributions to a mixed-culture assay.
    https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=36861,1396&retmode=xml (accessed 2026-10-15)
  6. bayarsaikhan2025_comparative: Bayarsaikhan et al. (2025). Comparative Study of Bioleaching Efficiency of Rare Earth Element from Different Carbonatite Ores in Mongolia. Metallurgical and Materials Engineering 31(3):300-309, DOI 10.63278/1371. Publisher-linked 13-page manuscript inspected; related study-family context, not independent replication.
    https://doi.org/10.63278/1371 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T20:23:42.296700+00:00 Codex (GPT-6; Codex) CREATE Curated a mixed natural ore and qualified pretreatment-associated acid leaching from full primary XML and original figures, resolved Tmix accessions and species labels, and preserved taxonomic and causal limits.

Record source: data/records/carbonatite-associated-rare-earth-ore.yaml