Phosphogypsum (PG) is a byproduct of phosphoric acid production and consists mainly of calcium sulfate (CaSO4). PG management is a critical concern in the phosphoric acid industry. As a solution, PG is decomposed to extract sulfur dioxide …
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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 …
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1. Introduction. Phosphogypsum (PG) is an industrial waste from the phosphate fertilizer production using the wet process (Becker, 1983).In general, the production of one ton of phosphoric acid generates about 4–5 tons of PG (Mazzilli et al., 2000).Yearly, the worldwide production of phosphogypsum is estimated to be around …
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Phosphogypsum contains calcium sulfate dehydrate as the main mineral, with small amounts of brushite, quartz, muscovite, and zoisite. Harmful elements, such as silicon, phosphorus, and fluorine, are mainly concentrated in the +0.15 mm and −0.025 …
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the phosphogypsum, the carbon dioxide and the ammonia, This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use ...
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The phosphogypsum used in this study was obtained from Sinochem Fuling Chemical Industry Co, Ltd. in Chongqing, China. A sample was dried at 40 °C for 12 h to remove the adsorbed water, and then placed in an airtight container at room temperature. Fig. 1 indicated that the main composition of phosphogypsum was calcium sulfate …
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Recovery of sulfur from phosphogypsum : conversion of calcium sulfate to calcium sulfide 1990. By Ragin, Margaret M.; Brooks, D. R. (Daniel R.), 1951- Series: ... The first step in the conversion scheme involves reduction of phosphogypsum to calcium sulfide. Effects of temperature, catalyst, reaction time, and type of reductant (carbon monoxide ...
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Semantic Scholar extracted view of "Phase transformation kinetics of calcium sulfate phases in strong CaCl2HCl solutions" by T. Feldmann et al. ... Hydrochloric Acid Regeneration via Calcium Sulfate Crystallization for Non‐Ferrous Chloride Leaching Processes. ... Phosphogypsum (PG) is a by-product of the wet-process phosphoric …
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The results show that, filtration rate of phosphogypsum was correlated to the mean diameter of crystals. In addition, induction time and co-crystallized (lattice) P 2 O 5 % in gypsum are decreased with increasing free sulfate content from 1.5% to 3.5%.
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Preparation of Calcium Sulfate Whisker by Atmospheric Acidification Method from Flue Gas Desulfurization Gypsum ... Therefore, in recent decades, the preparation of CSW from the industrial by-product, e.g. phosphogypsum [3,4], residue of citric acid [5], waste calcium chloride [6], flue gas desulfurization (FGD) gypsum[7,8], …
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Calcium sulfate hemihydrate whisker was prepared successfully by hydrothermal method with phosphogypsum; the morphology and synthesis rate of calcium sulfate hemihydrate whisker were very sensitive to reaction temperature, reaction time, and additives. ... Demopoulos GP (2009) Gypsum crystallization and hydrochloric acid regeneration by ...
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Approximately 1.6 % of the sulfate in phosphogypsum cannot be dissolved, likely due to the interaction of insoluble sulfate in phosphogypsum with other impurities, such as radium, which results in the formation of radium sulfate that has an even lower …
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Gasser et al. also enriched REEs into the carbonate matrix that is easily attacked in acid solution by transforming calcium sulfate in PG to calcium carbonate through reacting with sodium carbonate at 25 °C, and then REEs precipitated with calcium carbonate were leached out by the use of citric acid with a maximum leaching of 87.4% …
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This means that Ca(OH) 2 is partially converted to calcium sulfate and calcium carbonate by action of both sulfur oxide and carbon oxide gases which evolved from the fuel combustion. Thus, many trials were carried out to treat the industrial waste for eliminating all other impurities and to only one phase which used for synthesis of HAp.
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Phosphogypsum Decomposition by Char under a CO2 Atmosphere. ... Kinetics of the Hydrogen Reduction of the Calcium Sulfate Powder to Calcium Sulfide. Industrial & Engineering Chemistry Research 2002, 41 ... Regeneration of Sulfided Calcium-Based Sorbents by a Cyclic Process. Energy & Fuels 1996, 10 (3) ...
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These results confirm the successful synthesis of calcium molybdate nanoparticles from Moroccan phosphogypsum, demonstrating an effective pathway to valorize this industrial waste into a valuable ...
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A process of converting calcium sulphate produced as industrial waste product into potassium sulphate or sodium sulphate, in which a reaction of the calcium sulphate in fresh water, seawater or a mixture thereof is reacted at low pH with an anion exchange resin in the C-form to form a calcium chloride solution and a sulfate-charged ion exchange ...
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Although phosphogypsum is mainly calcium sulfate dihydrate, it contains elevated levels of impurities which originate primarily from the source phosphate rock used in P fertilizer production. The main environmental concerns associated with phosphogypsum are: (i) movement of fluoride, sulfate, total dissolved solids, certain …
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The calcium sulfate hemihydrate whiskers were prepared from phosphogypsum at hydrothermal condition. The influences of different organic acid (citric acid and poly (acrylic acid)) on the crystal morphology were detected, respectively.
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In the assays of physical and mechanical properties, calcined phosphogypsum (called FC) at a 450°C temperature, for a 4-hour period, was also used, which results in the form of anhydrite calcium sulfate II (CaSO 4), known as phosphoanhydrite, in order to improve the properties of mortars, as observed by Schaefer et al. [27 27 C. O. Schaefer, M. Cheriaf, …
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The discharge of lead and cadmium wastewater, along with the pollution caused by phosphogypsum, represents a particularly urgent environmental issue. This study employed a straightforward …
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DOI: 10.2139/ssrn.4372913 Corpus ID: 257272167; Gradient Removal of Si and P Impurities from Phosphogypsum and Preparation of Anhydrous Calcium Sulfate @article{Wang2023GradientRO, title={Gradient Removal of Si and P Impurities from Phosphogypsum and Preparation of Anhydrous Calcium Sulfate}, author={Mingshun …
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This work aims to investigate the possibility of recycling by-product phosphogypsum (PG) as raw material for preparing α-calcium sulfate hemihydrate (α-CSH) in chloride-free salt solution under mild conditions. The dehydration of PG in a concentrated Ca(NO 3) 2 solution at 97 °C under atmospheric pressure was analyzed.
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Using phosphogypsum-based excess-sulfate cement (PESC) for the preparation of super retarding materials. ... Furthermore, the high calcium sulfate concentration will promote the development of a lot of ettringite, which will soon precipitate on the surface of the unreacted raw material and prohibit its further hydration [34], [35]. …
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The performance characteristics and growth mechanism of CSW were reviewed in this paper.The preparation methods of CSW,hydrothermal synthesis and atmospheric acidification method were also introduced,especially the influence of preparation process on the growth of CSW by hydrothermal synthesis was detailed.The pretreatment method of …
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Simultaneous removal of phosphorus and organic contaminants from phosphogypsum using hydrothermal method for gypsum resource regeneration. Author links open overlay panel Jie Li a ... On this basis, by using K 2 S 2 O 8 as a mineralizer, PG was transformed into anhydrous calcium sulfate powder and the organic contaminants …
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BACKGROUND This work aims to investigate the possibility of recycling by‐product phosphogypsum (PG) as raw material for preparing α‐calcium sulfate hemihydrate (α‐CSH) in chloride‐free ...
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The anhydrous calcium sulfate (AH) whiskers were prepared in H 2 O-H 2 SO 4 autoclave-free hydrothermal system by using phosphogyp- sum (PG) as raw materials. The influences of solid / solution ratio, reaction time, H 2 SO 4 concentration and maleic acid on crystal growth were detected.The whiskers with smooth surface and high …
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Calcium sulfate (CS) is a kind of ceramic-based synthetic bone graft material with a long history of use for bone healing since the 19th century . Gypsum mainly consists of calcium sulfate dihydrate (CSD, CaSO 4 ·2H 2 O), which can be a promising raw material to produce calcium sulfate hemihydrate (CSH, CaSO 4 ·0.5H 2 O, Plaster of …
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Feature papers represent the most advanced research with significant potential for high impact in the field. A Feature Paper should be a substantial original Article that involves several techniques or approaches, provides an outlook for future research directions and describes possible research applications.
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