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Tungsten skarn-processing tailings secondary resource

Residual mineral solids generated by processing tungsten-bearing skarn ore. The curated case is historical tailings in the Smaltjärnen repository at the closed Yxsjöberg tungsten, copper and fluorspar mine in Sweden. The processing plant used gravity separation, magnetic separation and flotation. The characterized layered material contains scheelite among mixed silicate, carbonate, sulfide and other minerals; composition and particle liberation vary by sampled layer. This resource is distinct from tungsten as an element, pure scheelite, unprocessed ore, waste rock and a saleable concentrate. Hällström et al. document scheelite alteration, hydrous ferric oxide associations and tungsten transport in a field investigation of this repository; those geochemical observations do not establish microbial causation. No criticality designation is inherited from constituents, and the laboratory results below do not characterize all tungsten tailings.

Microbial & Biochemical Mechanisms (1)

Laboratory gravity concentration with limited magnetic selectivity

separation

Centrifugal gravity separation enriched tungsten in mixed solid concentrates from two sampled tailings layers. Separate magnetic tests retained most assayed sulfur in magnetic fractions but also retained most tungsten in the paramagnetic fraction, limiting the desired separation of scheelite. These physical operations do not demonstrate microbial activity, dissolved tungsten extraction or an isolated tungsten product. The proposed combined processing flowsheet was not demonstrated as an industrial reprocessing operation.

Experimental Context & Analytical Limits:
Mulenshi et al. focus on drill core 1_2, one location within the repository. Samples were dried at 105 degrees C for 48 h and split. Layers 1_2-1 and 1_2-8 were tested separately in a 58 mL laboratory Knelson concentrator, with two separation cycles per sample. Methods specify a minus-600 to plus-38 micrometre feed fraction and less than 2 kg; Table 6 labels the actual feeds only as minus-600 micrometres and reports 521.42 and 499.64 g, respectively. Table 3 gives 1500 rpm, 60 G, fluidization water at 3.5 L/min and 2 kPa. Separate dry low- and high-intensity magnetic tests used plus-75 micrometre material from layers 1_2-4 and 1_2-8. Products were chemically assayed by ICP-SFMS. The two gravity cycles are successive product separations, not independent replicate experiments. The article does not provide replicated separation outcomes or uncertainty estimates; the different layers are distinct feeds rather than matched controls.
Curated Evidence Points:
Sections 2.4.2 and 3.2.2, Figure 16 and Table 6 support redistribution of feed tungsten to solid concentrates. Table 6 reports 60.6% and 47.1% of the respective prepared-feed tungsten in the first concentrate from layers 1_2-1 and 1_2-8; these are W distributions, not concentrate purity or whole-repository recovery. The second concentrates and final tailings retain additional tungsten.
Figures 13 and 16-17 and Sections 3.2.2 and 5 show incomplete mineral liberation and limited selectivity: other assayed elements accompanied tungsten in concentrates. Recovery of scheelite was assessed using W content, while quantitative mineralogy of products remained future work. Table 6's feed-size shorthand omits the lower cutoff given in Methods; no unsieved-feed yield or exact dated concentration observations are asserted. The headline approximately 75% W result combines two concentrates from one feed, whereas the conclusion's 60.6% concerns its first concentrate.
Section 3.2.1, Figures 14-15 and Table 5 show most W in the paramagnetic product for both magnetic-test feeds, so the desired non-magnetic recovery was not achieved. Mineral locking, entrainment and surface alteration are possible limitations, not uniquely proven causes. Table 5 uses calculated magnetic-feed balances; these are not interchangeable with Table 6's actual gravity-feed assays.
Context_only Source: hallstrom2020
The separate P4 core and May-October 2018 groundwater and surface water sampling establish weathering and W-mobility context for Smaltjärnen, not replication of the physical separation experiment. The authors hypothesize carbonate-associated scheelite dissolution and W retention by iron oxyhydroxides. The field study has no inoculated-versus-sterile experiment establishing a microbial effect; downstream water also receives input from the separate Morkulltjärnen repository. Field concentrations and hypothesized pathways do not establish a recovery yield or successful remediation.

Sources & References

  1. mulenshi2019: Mulenshi, Khavari, Chehreh Chelgani and Rosenkranz (2019). Characterization and Beneficiation Options for Tungsten Recovery from Yxsjöberg Historical Ore Tailings. Processes 7(12):895. DOI 10.3390/pr7120895. Complete 19-page publisher PDF; Sections 2.1-2.4, 3.1-3.2 and 5, Tables 3-6 and Figures 1, 13-18.
    https://doi.org/10.3390/pr7120895 (accessed 2026-10-11)
  2. hallstrom2020: Hällström, Alakangas and Martinsson (2020; online 21 December 2019). Scheelite weathering and tungsten (W) mobility in historical oxidic-sulfidic skarn tailings at Yxsjöberg, Sweden. Environmental Science and Pollution Research 27:6180-6192. DOI 10.1007/s11356-019-07305-1. Complete 13-page repository PDF and PMC7044260 XML; Study area, Materials and methods, Figures 1-3 and 6-7, and Discussion.
    https://doi.org/10.1007/s11356-019-07305-1 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T18:23:59Z codex (GPT-6; codex) CREATE Created a distinct processing-derived tailings resource with primary physical separation evidence, qualified field context and explicit limits on feed basis, selectivity, microbial causality and deployment.

Record source: data/records/tungsten-skarn-tailings.yaml