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Nickel flotation tailings secondary resource

Residual mixed solids from flotation in nickel-ore beneficiation, distinct from the recovered flotation concentrate, unprocessed ore, a pure sulfide mineral and downstream smelter slag. The curated case is the material called lama in a 2010 UNESP thesis, supplied by Votorantim Metais from flotation at its Serra de Fortaleza-MG nickel extraction operation in Brazil. Original particles were reported as 50-100 micrometres. XRD indicated a heterogeneous silicate/carbonate assemblage with pyrrhotite; no pure-pyrrhotite feed or quantitatively established sulfide-hosted nickel fraction is assigned. Table 7 gives total Ni 0.30%, Cu 0.03% and Co 0.01%, versus aqua-regia-soluble Ni 0.25%, Cu 0.03% and Co 0.01%. The digestion-defined soluble fraction is not water-soluble metal. These are feed-specific measurements, not a universal tailings composition or an inherited criticality claim.

Microbial & Biochemical Mechanisms (1)

Culture-associated nickel mobilization in shaken acidic tailings flasks

bioleaching Microbial

Associated Organisms: Acidithiobacillus ferrooxidans (NCBITaxon:920)

Inoculation with source-labelled A. ferrooxidans LR was associated with higher nickel release than corresponding uninoculated treatments during shaken acidic leaching of these mixed tailings. Higher redox potential and changes in sulfide/carbonate diffraction peaks are consistent with biologically sustained oxidizing conditions and acid dissolution. They do not establish the exact mineral host of released nickel, an exclusively enzymatic pathway or an effect independent of inoculum chemistry and pH differences. The measured outcome was metal in leachate, not an isolated nickel product. Strong-acid and static treatments did not show the same inoculation advantage, limiting extrapolation beyond the flask design.

Experimental Context & Analytical Limits:
The study used duplicate 250 mL Erlenmeyer flasks with 150 mL T&K medium, 5% w/v original-size tailings and 5% v/v inoculum, at 30 degrees C and 150 rpm for 14 days. LR was reported to originate from acidic uranium-ore leachate at Lagoa Real, Bahia; no strain accession or independent authentication is supplied. Precultures grew in T&K at pH 1.8. Arms were nominally no-added-iron T&K, T&K plus 120 mmol/L Fe(II), and grown culture containing about 120 mmol/L Fe(III). Controls were the corresponding uninoculated medium or grown culture described as sterile. Experimental pH rose and was corrected with sulfuric acid; Figure 13 documents differing trajectories. Flame atomic absorption measured leachate metals, with total-feed metal determined by HF/microwave digestion and a separate aqua-regia-soluble denominator. Cell washing is stated only for separate respirometry, not for these leaching inocula; no-added-iron medium therefore does not establish zero iron or an inoculum-broth-matched comparison. A later 50-day shaken repeat and static beaker tests used separate experimental series.
Curated Evidence Points:
Pages 33, 36-40 and 50-53 identify the flotation residue and laboratory protocol. Figures 13-14 and Table 11 on pages 62-63 report day-14 extraction as percentages of total feed Ni: inoculated/control 42/24% without added iron, 46/30% with ferrous iron and 45/37% with grown ferric culture. Corresponding total-Cu percentages were 16/14%, 17/14% and 16/13%. These are reported treatment comparisons, without displayed replicate uncertainty or a statistical significance test. The adjacent percentages against the smaller aqua-regia-soluble Ni fraction are not total-metal extraction yields. No leachate concentration is converted here into isolated-product recovery.
Figures 13 and 15 show generally higher redox in inoculated flasks and changed solid-phase diffraction after treatment. Pyrrhotite and dolomite peaks declined, and additional peaks were assigned to jarosite, but silicate-jarosite peak overlap and mixed feed prevent a quantitative mineral mass balance. The proposed acid and ferric-iron mediation is consistent with these observations; a killed-cell control, blank-corrected inoculum chemistry, identical pH trajectory and authenticated strain-specific mechanism are not demonstrated.
The separate 50-day series in Figures 16-17 and Table 13 also showed higher Ni mobilization in the first three inoculated arms. The strong-acid arm did not: Table 13 reports total-Ni extraction of 44% with inoculated ferric culture plus 1.25 M sulfuric acid and 45% in its control. Table 2 describes that control as sterile acid alone, so the iron chemistry is not matched and the result does not uniquely demonstrate acid inhibition of living cells. Some total/soluble values elsewhere in this table cannot be reconciled using rounded Table 7 composition; those denominators are not pooled or recalculated.
Static beaker tests in Figures 19-22 and Table 14 showed similar or greater nickel mobilization in controls. The source proposes restricted oxygen and mass transfer, without directly measuring those causes. The static protocol includes inconsistent iron concentrations between figure captions and discordant total/soluble percentage accounting, so precise static yields are not adopted. Those null comparisons remain evidence against treating the shaken-flask benefit as universal. Neither the industrial origin of the waste nor these laboratory tests demonstrates pilot or industrial microbial recovery.

Sources & References

  1. munoz_blandon2010: Nury Alexandra Munoz Blandon (2010). Recuperacao de niquel e outros metais a partir de diferentes fontes (rejeitos minerais de processo industrial e pentlandita (Ni,Fe)9S8) por lixiviacao bacteriana e acida. Doctoral thesis, UNESP, Instituto de Quimica, Araraquara. Official repository handle 11449/100745, issued 15 July 2010; repository accession in 2014 is not the publication year. Original 125-page PDF; source pp. 33, 36-40, 50-53 and 61-72, Tables 1-3, 7 and 11-14, Figures 4-6 and 13-22. Repository title wording differs slightly from the thesis front matter.
    https://hdl.handle.net/11449/100745 (accessed 2026-10-14)
  2. ncbi_ferrooxidans: NCBI Taxonomy 920, Acidithiobacillus ferrooxidans, species entry. Resolves the source species name without authenticating the LR experimental isolate or equating it with a type-strain accession.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=920&mode=info (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T05:35:29.027316+00:00 codex (GPT-6; codex) CREATE Created a nickel-beneficiation flotation-tailings resource with conditional culture-associated nickel release, explicit controls, total-metal denominators and static/strong-acid nulls.

Record source: data/records/nickel-flotation-tailings.yaml