Fe/Mg Silicate Mining Residues as Solid Oxygen Carriers for Chemical Looping Combustion of Torrefaction Volatiles
Bibliographic record
Abstract
Torrefaction of woody biomass is a thermal treatment often used to increase biomass energy density prior to its thermochemical conversion. The feasibility of integrated torrefaction, where the energy required for torrefaction is provided from the burning of its self-released volatiles, while the resulting carbon dioxide is subsequently captured in a permanent sink, is an original avenue, which was investigated in this study from the point of view of mining residue valorization. The use of abundant, cheap, and comminuted minerals as solid oxygen carriers for chemical looping combustion (CLC) and as carbon sinks for mineral carbonation in combination with torrefaction of woody biomass was studied. The mining residue consisted of iron-rich (17.3 wt %) post-nickel recovery chrysotile/lizardite silicate minerals. Air pre-calcination of the mineral at 700 °C helped boost the extra-framework iron fraction up to 66%, mainly in the form of hematite, as evidenced from Mössbauer spectroscopy. Such a calcined oxygen carrier was then tested in airless torrefaction–CLC tied configuration under gas recirculation over the temperature range of 500–700 °C to burn the volatiles released during the torrefaction of birch at 260–300 °C. Up to 96% of the carbon released from the torrefied birch as volatiles was converted in the CLC bed into CO 2, highlighting the ability of the residue for burning torrefaction volatiles. The residue was finally tested in a torrefaction–CLC–carbonation configuration under gas recirculation for burning the torrefaction volatiles and capturing the produced carbon dioxide for various torrefaction, CLC, and carbonation temperatures. Up to 20% of produced CO 2 was sequestrated using this concept at the optimal carbonation bed temperature of 50 °C.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".