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Enargite-pyrite concentrate primary resource

Mixed high-arsenic mineral concentrates represented by DC-I, DC-II and DC-III in Okibe et al. (2022), distinct from pure enargite or pyrite and from elemental copper or arsenic. Company-supplied mineral liberation analyses assign enargite and pyrite, respectively, as 51.8 and 34.6 wt% in DC-I, 37.4 and 47.3 wt% in DC-II, and 26.1 and 63.1 wt% in DC-III. Original XRD also identifies these phases, with a source-labelled tennantite contribution in DC-III. Other copper minerals occur, so dissolved copper cannot be assigned exclusively to enargite. DC-I and DC-III were supplied by Sumitomo Metal Mining and DC-II by JX Nippon Mining and Metals; mine, batch and detailed beneficiation provenance are not reported. The paper frames dirty concentrates as flotation waste separated from clean smelter feed. This record denotes the characterized concentrated geological feeds without asserting prior disposal, a tailings stockpile or a traded product specification. No mineral-species identifier or constituent criticality designation is transferred to the mixed resource.

Microbial & Biochemical Mechanisms (1)

Conditional acidophile-associated copper dissolution at high pulp loading

bioleaching Microbial

Associated Organisms: Sulfobacillus thermosulfidooxidans (NCBITaxon:28034)

In 60-day laboratory mixed-culture assays, source-reported final dissolved copper percentages without versus with 0.05% w/v activated carbon were 35 versus 29% for DC-I, 25 versus 29% for DC-II, and 22 versus 27% for DC-III. Figure 3 defines these percentages as soluble copper on day 60 relative to copper in the respective concentrate. They are mixed-feed solution outcomes, not phase-specific extraction or isolated-metal yields. Carbon addition therefore was not uniformly beneficial. DC-II inoculum-free controls reached 14% without carbon and 15% with carbon in Figure S1, lower than the corresponding inoculated systems. These controls used unsterilized feed, had different evolving pH/redox trajectories, and were not performed for DC-I or DC-III. They support an inoculum-associated difference for DC-II under the tested conditions, not a universal microbial advantage or the necessity of any named consortium member.

Experimental Context & Analytical Limits:
As-received, unwashed and unsterilized feed was loaded at 20% w/v in 200 mL acidophile basal salts medium in duplicate 500 mL flasks, with 0.01% w/v yeast extract, initial pH 1.5 adjusted with sulfuric acid, 10% v/v pre-grown mixed inoculum, 45 degrees C and 150 rpm. Cultures had been repeatedly pre-grown on each particular concentrate. The six initially introduced source-labelled members were Acidiplasma sp. Fv-Ap, Acidithiobacillus caldus KU (DSM 8584), Acidimicrobium ferrooxidans ICP (DSM 10331), Sulfobacillus sibiricus N1 (DSM 17363), S. thermotolerans Kr1 (DSM 17362) and S. thermosulfidooxidans AT-1 (DSM 9293). The structured organism names one reported member only; no time-resolved community census, verified strain accession or member-specific causal result is provided. Carbon was Shirasagi DO-5 with D50 10.9 micrometres. Doses 0.025, 0.05 and 0.1% were reportedly tested, but only 0 and 0.05% are plotted; the statement that nonzero doses gave nearly identical results is not an available complete dose-response dataset. Feed D50 values were 57.7, 62.8 and 81.2 micrometres for DC-I, DC-II and DC-III. Mineral assemblage, particle size and possible flotation-reagent carryover vary together, precluding a controlled estimate of the pyrite/enargite ratio alone. Total soluble Cu, As and Fe were measured by ICP-OES; no oxidation-state speciation or complete sampling-corrected mass balance is demonstrated. The high pulp loading is a flask feasibility experiment, not industrial deployment.
Curated Evidence Points:
Sections 2.1-2.3, Table 1, Figures 1-3 and Figure S1 support feed identity, the specified inoculated comparison and reported copper endpoints. DC-I carbon lowered redox potential and copper dissolution; DC-II showed only a modest difference; DC-III carbon raised redox potential and copper dissolution. Proposed inhibition by residual flotation chemicals, carbon-assisted detoxification, cell attachment and particular iron-redox mechanisms are explanations, not directly isolated causes in this experiment. pH was not held equal between arms.
Section 3.2.1 and Figure 3a report dissolved arsenic of 6.5% without carbon versus 1.0% with carbon in DC-I. The abstract's lowest-arsenic wording for the highest-copper DC-I carbon-free condition is therefore not adopted as an ordering across all arms. For DC-II, Section 3.2.2 reports 5.0% dissolved arsenic without carbon whereas Figure 3c labels that arsenic endpoint 6.6%; its 5.0% label belongs to iron. This disagreement remains unresolved. The 9.9% arsenic endpoint with carbon is reported consistently in that paragraph and figure. DC-III with carbon reaches 24% dissolved arsenic. These are liquid-phase fractions of feed arsenic, not measured arsenic-immobilization yields.
Section 3.3, Figure 4, Figures 5-6, Table 2 and Figure S2 support association of As/Fe/O/Cu/S-bearing secondary material with residual sulfide grains, while XRD did not identify a crystalline arsenic precipitate. The proposed mixture of amorphous ferric arsenate, cupric arsenate, basic ferric sulfate and sulfur is tentative; neither pure scorodite nor long-term arsenic stability is demonstrated. Figure 5 examines DC-I without carbon, Figure 6 DC-II with 0.05% carbon, and Table 2 DC-III without carbon, all after 60 days; these observations are not interchangeable assay replicates. Section 3.3 calls spot 12 both enargite-like and gel-like secondary material, while Table 2 assigns spot 12 to enargite and spot 11 to secondary precipitates. No exact spot-based mineral formula is adopted. Figure 4 uses the same solution time series and does not supply an independent precipitation experiment or a closed arsenic balance.
Context_only Source: oyama_2021
The earlier D3, Eb and Ea assays used different mixed mineral compositions at 1% w/v pulp, four introduced acidophiles, external iron and sulfur, and feed-dependent acid adjustment. Their outcomes are not pooled with the 2022 20% assays or treated as independent replication of the same feed experiment. The 2021 introduction also cites a separate 2020 concentrate with 37.4% enargite and 47.3% pyrite, matching the nominal 2022 DC-II composition; this is a possible material-provenance connection, not proof of identical batches or independent experimental replication. Those 2020 results are not imported here.
Verifies the one asserted species identifier and reported type-strain aliases, without establishing the identity, abundance or causal role of cells present after repeated mixed-culture pre-growth.

Sources & References

  1. okibe_2022: Okibe N, Hayashi K, Oyama K, Shimada K, Aoki Y, Suwa T and Hirajima T (2022). Bioleaching of Enargite/Pyrite-Rich Dirty Concentrate and Arsenic Immobilization. Minerals 12(4):449; DOI 10.3390/min12040449. Complete original 11-page article, Figures 1-6, Tables 1-2 and two-page supplement Figures S1-S2.
    https://doi.org/10.3390/min12040449 (accessed 2026-10-12)
  2. oyama_2021: Oyama K, Takamatsu K, Hayashi K, Aoki Y, Kuroiwa S, Hirajima T and Okibe N (2021). Carbon-Assisted Bioleaching of Chalcopyrite and Three Chalcopyrite/Enargite-Bearing Complex Concentrates. Minerals 11(4):432; DOI 10.3390/min11040432. Sections 2-3 and Figure 1 establish the distinct D3, Eb and Ea feeds and lower-loading experiment; comparison context only.
    https://doi.org/10.3390/min11040432 (accessed 2026-10-12)
  3. ncbi_sulfobacillus: NCBI Taxonomy 28034, Sulfobacillus thermosulfidooxidans, species; DSM 9293 and AT-1 are listed as type-strain designations. Identifier context only, not authentication of the experimental stock or consortium composition.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=28034&mode=Info (accessed 2026-10-12)

Curation History

Timestamp Curator Action Summary
2026-10-12T11:16:00.966888Z Codex (GPT-6) create Curated the mixed feed identity and conditional 2022 high-pulp bioleaching evidence from complete main and supplementary originals, preserving control limits, differing carbon responses, source discrepancies and tentative secondary phases; separated 2021 comparison experiments.

Record source: data/records/enargite-pyrite-concentrate.yaml