A green process for recovery of H<sub>2</sub>SO<sub>4</sub> and Fe<sub>2</sub>O<sub>3</sub> from FeSO<sub>4</sub>·7H<sub>2</sub>O by modeling phase equilibrium of the Fe(П)––H<sup>+</sup>–Cl<sup>–</sup> system
Bibliographic record
Abstract
Ferrous sulfate heptahydrate FeSO 4 ·7H 2 O is a major waste produced in titanium dioxide industry by the sulfate process and has caused heavy environmental problem. A new green process for the treatment of FeSO 4 ·7H 2 O was proposed to make use of iron source and recycle sulfate source as H 2 SO 4 . It was found that by adding concentrated HCl to the FeSO 4 solution, FeCl 2 ·4H 2 O was crystallized out, which was subsequently calcined to produce Fe 2 O 3 and HCl. Concentrated H 2 SO 4 solution (about 65 wt %) was obtained by evaporating the FeCl 2 ·4H 2 O‐saturated filtrate. To facilitate the process development and design, the solubilities of FeCl 2 ·4H 2 O in HCl, H 2 SO 4 , and HCl + H 2 SO 4 solutions were measured and the experimental data were regressed with both the mixed‐solvent electrolyte model and the electrolyte NRTL model. On the basis of the prediction of the optimum conditions for the crystallization of FeCl 2 ·4H 2 O, material balance of the new process was calculated. FeCl 2 ·4H 2 O and Fe 2 O 3 were obtained from a laboratory‐scale test with about 70% recovery of ferrous source for a single cycle, indicating the feasibility of the process. © 2017 American Institute of Chemical Engineers AIChE J , 63: 4549–4563, 2017
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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 | 0.005 | 0.002 |
| Meta-epidemiology (narrow) | 0.003 | 0.003 |
| Meta-epidemiology (broad) | 0.004 | 0.003 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.005 |
| Open science | 0.004 | 0.001 |
| Research integrity | 0.002 | 0.006 |
| 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; both teacher heads agree on what is shown here.
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".