Preparation of α-Calcium Sulfate Hemihydrate by Reaction of Sulfuric Acid with Lime
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Bibliographic record
Abstract
Direct preparation of α-calcium sulfate hemihydrate out of sulfuric acid solution by reaction with lime under atmospheric pressure conditions is systematically investigated. Two preparation methods are investigated: one involving addition of dry lime to sulfuric acid solution (standard procedure) and the other involving addition of sulfuric acid solution to slaked lime (reverse procedure). On the basis of the standard procedure, the operating window is first determined, followed by thorough examination of preparation conditions such as acidity, retention time and CaO/H 2 SO 4 molar ratio. Dihydrate was found to form as intermediate phase that converts to hemihydrate under all tested conditions. The typical morphology of α-hemihydrate crystals produced by the standard procedure is needle-shaped with 50−100 μm length and 1−3 μm thickness. However, when the reverse procedure was used, a different growth mechanism apparently applied yielding shorter (∼60 μm) but thicker (5−10 μm) column-shaped crystals within otherwise the same operating window.
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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 | 0.001 | 0.000 |
| 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 | 0.000 | 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 it