Preparing high‐purity calcium carbonate and potassium sulphate at a low cost using industrial by‐product gypsum
Bibliographic record
Abstract
Abstract The substantial annual production and low utilization of industrial by‐product gypsum (IBPG) have led to significant ecological, environmental, and safety challenges. To address these issues, a cost‐effective and environmentally friendly approach to convert IBPG and CO 2 ‐sourced raw material into high‐value products, that is, 100% high‐purity of calcium carbonate (CaCO 3 ), ammonium chloride (NH 4 Cl), and potassium sulphate (K 2 SO 4 ), is proposed under ambient conditions by using a developed two‐step method. By employing a recyclable phase transfer catalyst of ammonium acetate and a mixed solution containing saturated terminal products as a simulated mother liquor, efficient leaching of low‐solubility IBPG, impurity separation, and enhanced reaction rates are simultaneously achieved. Some crucial conditions for preparing high‐value target products are optimized, and many traditional by‐products (e.g., syngenite, koktaite, calcium acetate hydrate, K 2 SO 4 · (NH 4 ) 2 SO 4 , and KCl · NH 4 Cl) are successfully suppressed. The favourable recirculation of the mother liquor demonstrated the prominent advantage in production cost reduction and environmental protection, confirming its industrial feasibility. Therefore, a promising, low‐cost, and sustainable solution for IBPG's resource utilization to prepare high‐value products is put forward here, providing some significant theoretical and industrial guidelines for solid waste disposal and carbon fixation.
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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) | 0.001 | 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".