Enhanced Beneficiation of Ultramafic Nickel Ores Using Novel Reagents
Bibliographic record
Abstract
Due to its outstanding physical and chemical properties, nickel (Ni) is used in the manufacture of stainless steel, batteries, catalysts etc. However, high Ni demand has rapidly depleted high-grade sulfide deposits, leading the mining industry to seek alternative Ni sources such as low-grade ultramafic Ni ores. Processing of these ores is difficult due to their high content of the gangue mineral, serpentine, which slime coats the Ni-bearing mineral, pentlandite, and increases slurry viscosity. In response to stringent environmental regulations, process water is recycled, introducing significant amounts of Ca2+ and Mg2+ into flotation unit operations, which exacerbates the slime coating phenomenon. Additionally, the mining industry is under pressure to decarbonize its operations: it currently accounts for 4–7% of global greenhouse gas emissions. To overcome these challenges, the first part of this thesis focuses on decarbonizing mineral processing operations by utilizing carbon dioxide (CO2) in unit operations such as flotation and rheology modification. CO2 conditioning prior to flotation prevented slime coating and mitigated the detrimental impacts of divalent cations by permanently storing CO2 as metal carbonates. Zeta potential measurements and theoretical calculations indicated adsorption of metal carbonates onto the serpentine surface and microflotation experiments demonstrated increased Ni recovery. The second part of the thesis focuses on using sustainable flotation reagents for separation of pentlandite from ultramafic Ni ore. Citrate and Oxalate were shown to chelate with divalent cations to form metal-citrate or metal-oxalate chelates, which desorb from the pentlandite surface and adsorb onto the serpentine surface. Removal of chelates restored the charge and hydrophobicity of pentlandite whereas it reversed the charge of serpentine. The induced electrostatic dispersion among the mineral particles enhanced selective separation of pentlandite. The third part of the thesis explored the use of citrate and oxalate as rheology modifiers during slurry transport operations. Both reagents prevented bridging between serpentine particles and were selectively adsorbed onto the brucite plane of serpentine. Theoretical calculations and AFM measurements showed repulsive/weakened interactions between the brucite plane and silica/edge plane, which broke the mineral microstructure. Rheology investigations confirmed weakened interparticle interactions, manifested as significant decreases in slurry viscosity, yield stress, and storage modulus.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".