Process for the Remediation of Titanogypsum (Red Gypsum) Using Weak Acid and CaCl<sub>2</sub> to Produce Saleable α-Gypsum and FeCl<sub>2</sub>·4H<sub>2</sub>O
Bibliographic record
Abstract
The disposal of titanogypsum, also known as red gypsum, which is generated during the titanium dioxide sulfate process, has become a significant environmental challenge. We propose a new process to recover iron impurities such as FeCl 2 ·4H 2 O and to convert titanogypsum to saleable hemihydrate gypsum. For this purpose, we use HCl–FeCl 2 solution generated via the reaction of H 2 SO 4 –FeSO 4 with CaCl 2 to leach iron hydroxide from titanogypsum. The hemihydrate precipitation and phase-transition kinetics of the reaction of HCl–H 2 SO 4 –FeSO 4 with CaCl 2 are experimentally investigated at 353 K. The common ion effect of CaCl 2 in the FeCl 2 solution for FeCl 2 ·4H 2 O crystallization is predicted by NRTL modeling of the solid–liquid equilibria of the FeCl 2 –CaCl 2 –H 2 O system. High-quality, saleable α-gypsum and FeCl 2 ·4H 2 O solids obtained by treating titanogypsum samples provided by a commercial processing plant further shows that the new process is feasible.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| 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".