Documents disponibles écrits par cet auteur

a - Calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions / Baohong Guan in Chemical engineering journal, Vol. 174 N° 1 (Octobre 2011) 

Public ISBD [article]  in Chemical engineering journal > Vol. 174 N° 1 (Octobre 2011) . - pp. 296–303 Titre : a - Calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions Type de document : texte imprimé Auteurs : Baohong Guan, Auteur ; Yang Li, Auteur ; Hailu Fu, Auteur Année de publication : 2012 Article en page(s) : pp. 296–303 Note générale : Génie chimique Langues : Anglais (eng) Mots-clés : Alpha-calcium  sulfate  hemihydrate  FGD  gypsum  Salt  solution  recycling  Pilot  test Résumé : A pilot scale preparation of α-calcium sulfate hemihydrate (α-HH) from flue gas desulfurization (FGD) gypsum was conducted for the first time in mixed salt solutions under atmospheric pressure. The effects of salt solution recycling on the transition of α-HH from FGD gypsum were investigated by a comparison with that in laboratory scale, focusing on the dehydration rate of FGD gypsum, the crystal morphology, chemical composition and mechanical strength of the products. α-HH could be transformed from FGD gypsum in 3.5–6.0 h even though the salt solution was recycled seven times in laboratory tests and eight times in pilot tests. The product obtained in pilot scale has a purity of 95% and the α-HH crystals are mostly a prismatic morphology, with volume weighted mean diameter (D[3,4]) in the range of 52.9–84.0 μm, 2 h bending strength of 5.6–6.2 MPa and 3 d compressive strength of 15.7–25.3 MPa. The salt solution recycling achieves 56% recovery of salts in pilot scale and puts almost no negative impact on the product quality, which can be one of the best strategies to reduce the production cost. It is very likely that the process of salt solution recycling can be adopted in industry. ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science/article/pii/S1385894711010916 [article] a - Calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions [texte imprimé] / Baohong Guan, Auteur ; Yang Li, Auteur ; Hailu Fu, Auteur . - 2012 . - pp. 296–303. Génie chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 174 N° 1 (Octobre 2011) . - pp. 296–303 Mots-clés : Alpha-calcium  sulfate  hemihydrate  FGD  gypsum  Salt  solution  recycling  Pilot  test Résumé : A pilot scale preparation of α-calcium sulfate hemihydrate (α-HH) from flue gas desulfurization (FGD) gypsum was conducted for the first time in mixed salt solutions under atmospheric pressure. The effects of salt solution recycling on the transition of α-HH from FGD gypsum were investigated by a comparison with that in laboratory scale, focusing on the dehydration rate of FGD gypsum, the crystal morphology, chemical composition and mechanical strength of the products. α-HH could be transformed from FGD gypsum in 3.5–6.0 h even though the salt solution was recycled seven times in laboratory tests and eight times in pilot tests. The product obtained in pilot scale has a purity of 95% and the α-HH crystals are mostly a prismatic morphology, with volume weighted mean diameter (D[3,4]) in the range of 52.9–84.0 μm, 2 h bending strength of 5.6–6.2 MPa and 3 d compressive strength of 15.7–25.3 MPa. The salt solution recycling achieves 56% recovery of salts in pilot scale and puts almost no negative impact on the product quality, which can be one of the best strategies to reduce the production cost. It is very likely that the process of salt solution recycling can be adopted in industry. ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science/article/pii/S1385894711010916

Effect of Mg2+ ions on the nucleation kinetics of calcium sulfate in concentrated calcium chloride solutions / Baohong Guan in Industrial & engineering chemistry research, Vol. 49 N° 12 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5569–5574 Titre : Effect of Mg2+ ions on the nucleation kinetics of calcium sulfate in concentrated calcium chloride solutions Type de document : texte imprimé Auteurs : Baohong Guan, Auteur ; Liuchun Yang, Auteur ; Zhongbiao Wu, Auteur Année de publication : 2010 Article en page(s) : pp. 5569–5574 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Metastable  calcium  sulfate  hemihydrate  Nucleation  kinetics Résumé : The precipitation kinetics of the metastable calcium sulfate hemihydrate (HH) from aqueous solutions has seldom been addressed. For the first time, the nucleation kinetics of calcium sulfate (probably in α-HH form) in concentrated CaCl2 solutions at 90 °C and the effect of Mg2+ ions were investigated by spontaneous precipitation experiments and a turbidity monitoring method. The results indicate that, at a moderate supersaturation with respect to calcium sulfate, Mg2+ ions retard the nucleation with 0.01 M Mg2+ ions showing the strongest effect; at a higher supersaturation, the inhibition effect decreases when the concentration of Mg2+ ions increases from 0.001 to 0.10 M, and 0.20 M Mg2+ ions show a promoting effect on the precipitation. The interfacial tension values increase with the concentration of Mg2+ ions, resulting in a decrease in nucleation rate in Mg2+ ion-containing solutions compared to Mg2+ ion-free solutions. This may indicate an involvement of Mg2+ ions in the surface reaction during calcium sulfate precipitation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie902022b [article] Effect of Mg2+ ions on the nucleation kinetics of calcium sulfate in concentrated calcium chloride solutions [texte imprimé] / Baohong Guan, Auteur ; Liuchun Yang, Auteur ; Zhongbiao Wu, Auteur . - 2010 . - pp. 5569–5574. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5569–5574 Mots-clés : Metastable  calcium  sulfate  hemihydrate  Nucleation  kinetics Résumé : The precipitation kinetics of the metastable calcium sulfate hemihydrate (HH) from aqueous solutions has seldom been addressed. For the first time, the nucleation kinetics of calcium sulfate (probably in α-HH form) in concentrated CaCl2 solutions at 90 °C and the effect of Mg2+ ions were investigated by spontaneous precipitation experiments and a turbidity monitoring method. The results indicate that, at a moderate supersaturation with respect to calcium sulfate, Mg2+ ions retard the nucleation with 0.01 M Mg2+ ions showing the strongest effect; at a higher supersaturation, the inhibition effect decreases when the concentration of Mg2+ ions increases from 0.001 to 0.10 M, and 0.20 M Mg2+ ions show a promoting effect on the precipitation. The interfacial tension values increase with the concentration of Mg2+ ions, resulting in a decrease in nucleation rate in Mg2+ ion-containing solutions compared to Mg2+ ion-free solutions. This may indicate an involvement of Mg2+ ions in the surface reaction during calcium sulfate precipitation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie902022b

Interaction between α-calcium sulfate hemihydrate and superplasticizer from the point of adsorption characteristics, hydration and hardening process / Baohong Guan in Cement and concrete research, Vol. 40 N° 2 (02 ex.) (Fevrier 2010) 

Public ISBD [article]  in Cement and concrete research > Vol. 40 N° 2 (02 ex.) (Fevrier 2010) . - pp. 253-259 Titre : Interaction between α-calcium sulfate hemihydrate and superplasticizer from the point of adsorption characteristics, hydration and hardening process Type de document : texte imprimé Auteurs : Baohong Guan, Auteur ; Qingqing Ye, Auteur ; Jiali Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 253-259 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : α-calcium  sulfate  hemihydrate  Superplasticizer  Adsorption  Hydration  Hardening Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Superplasticizers (SPs), namely sulfonated melamine formaldehyde (SMF) and polycarboxylate (PC), were independently admixed with α-calcium sulfate hemihydrate based plaster to improve the material's performance. SMF and PC gave, respectively, 38% and 25% increases in the 2 h bending strength at the optimum dosages of 0.5 wt.% and 0.3 wt.%, which are determined essentially by the maximum water-reducing efficiency. The peak shift of binding energy of Ca2p3/2 detected by X-ray photoelectron spectroscopy (XPS) suggests that SPs are chemically adsorbed on gypsum surface. A careful examination of the strength development of set plaster allowed the hydration and hardening process to be divided roughly into five stages. SMF accelerates early hydration, while PC decelerates it. Both SPs allowed similar maximum water reductions, giving a more compact structure and a decrease in total pore volume and average pore diameter, and thus leading to higher strengths in the hardened plasters with SPs. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWG-4XJF38H-1&_user=6 [...] [article] Interaction between α-calcium sulfate hemihydrate and superplasticizer from the point of adsorption characteristics, hydration and hardening process [texte imprimé] / Baohong Guan, Auteur ; Qingqing Ye, Auteur ; Jiali Zhang, Auteur . - 2010 . - pp. 253-259. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 40 N° 2 (02 ex.) (Fevrier 2010) . - pp. 253-259 Mots-clés : α-calcium  sulfate  hemihydrate  Superplasticizer  Adsorption  Hydration  Hardening Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Superplasticizers (SPs), namely sulfonated melamine formaldehyde (SMF) and polycarboxylate (PC), were independently admixed with α-calcium sulfate hemihydrate based plaster to improve the material's performance. SMF and PC gave, respectively, 38% and 25% increases in the 2 h bending strength at the optimum dosages of 0.5 wt.% and 0.3 wt.%, which are determined essentially by the maximum water-reducing efficiency. The peak shift of binding energy of Ca2p3/2 detected by X-ray photoelectron spectroscopy (XPS) suggests that SPs are chemically adsorbed on gypsum surface. A careful examination of the strength development of set plaster allowed the hydration and hardening process to be divided roughly into five stages. SMF accelerates early hydration, while PC decelerates it. Both SPs allowed similar maximum water reductions, giving a more compact structure and a decrease in total pore volume and average pore diameter, and thus leading to higher strengths in the hardened plasters with SPs. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWG-4XJF38H-1&_user=6 [...]

Solubility and phase transitions of calcium sulfate in KCl solutions between 85 and 100 °C / Liuchun Yang in Industrial & engineering chemistry research, Vol. 48 N° 16 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 16 (Août 2009) . - pp. 7773–7779 Titre : Solubility and phase transitions of calcium sulfate in KCl solutions between 85 and 100 °C Type de document : texte imprimé Auteurs : Liuchun Yang, Auteur ; Baohong Guan, Auteur ; Zhongbiao Wu, Auteur Année de publication : 2009 Article en page(s) : pp. 7773–7779 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Calcium  sulfate  KCl  solution Résumé : The solubility(s) of the three phases of CaSO4, namely, CaSO4·2H2O (DH), CaSO4·0.5H2O (α-HH), and CaSO4 (AH II), in 0.0−18.0 wt % KCl solutions were systemically investigated at temperatures ranging from 85 to 100 °C. At fixed temperature, the solubility(s) of the three phases all change with KCl concentration and possess a maximum value. The relative magnitudes of the variance of solubility for AH and α-HH are larger than that for DH. This was considered to be correlated to the combined effects of the temperature and concentration of KCl solution on the activity coefficients and water activity. The phase transition behaviors of α-HH and DH are presented with possible intermediate phases, which can be well-explained by the solubility difference of the three forms of CaSO4 and the tendency of forming görgeyite (K2Ca5(SO4)6·H2O). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900372j [article] Solubility and phase transitions of calcium sulfate in KCl solutions between 85 and 100 °C [texte imprimé] / Liuchun Yang, Auteur ; Baohong Guan, Auteur ; Zhongbiao Wu, Auteur . - 2009 . - pp. 7773–7779. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 16 (Août 2009) . - pp. 7773–7779 Mots-clés : Calcium  sulfate  KCl  solution Résumé : The solubility(s) of the three phases of CaSO4, namely, CaSO4·2H2O (DH), CaSO4·0.5H2O (α-HH), and CaSO4 (AH II), in 0.0−18.0 wt % KCl solutions were systemically investigated at temperatures ranging from 85 to 100 °C. At fixed temperature, the solubility(s) of the three phases all change with KCl concentration and possess a maximum value. The relative magnitudes of the variance of solubility for AH and α-HH are larger than that for DH. This was considered to be correlated to the combined effects of the temperature and concentration of KCl solution on the activity coefficients and water activity. The phase transition behaviors of α-HH and DH are presented with possible intermediate phases, which can be well-explained by the solubility difference of the three forms of CaSO4 and the tendency of forming görgeyite (K2Ca5(SO4)6·H2O). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900372j

Thermodynamic preparation window of alpha calcium sulfate hemihydrate from calcium sulfate dihydrate in non - electrolyte glycerol – water solution under mild conditions / Baohong Guan in Industrial & engineering chemistry research, Vol. 50 N° 23 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13561-1356 Titre : Thermodynamic preparation window of alpha calcium sulfate hemihydrate from calcium sulfate dihydrate in non - electrolyte glycerol – water solution under mild conditions Type de document : texte imprimé Auteurs : Baohong Guan, Auteur ; Guangming Jiang, Auteur ; Hailu Fu, Auteur Année de publication : 2012 Article en page(s) : pp. 13561-1356 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Electrolyte  Preparation Résumé : Through vapor pressure measurements, water activities of the glycerol-water solution were first examined under temperatures of 30―85 °C and glycerol concentrations of 0―50 mol %. The water activity is the only determinant of phase-transition point among CaSO4·2H2O (DH), α-CaSO4·0.5H2O (α-HH), and CaSO4 (AH) in glycerol-water solution. Accordingly, a phase-transition diagram was constructed as a function of temperature (0―140 °C) and glycerol concentration (0―50 mol %), which provided a thermodynamic preparation window of α-HH from DH. Controlling glycerol concentration and temperature within the window, direct transition of DH to α-HH can be regnlated. However, the window is apt to shrink as the operating time is shortened, indicating that its available profile is directed by transition kinetics ofDH to α-HH besides transition thermodynamics. Overall, the glycerol―water solution could act as a novel category of nonelectrolyte medium for α-HH preparation from DH. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267515 [article] Thermodynamic preparation window of alpha calcium sulfate hemihydrate from calcium sulfate dihydrate in non - electrolyte glycerol – water solution under mild conditions [texte imprimé] / Baohong Guan, Auteur ; Guangming Jiang, Auteur ; Hailu Fu, Auteur . - 2012 . - pp. 13561-1356. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13561-1356 Mots-clés : Electrolyte  Preparation Résumé : Through vapor pressure measurements, water activities of the glycerol-water solution were first examined under temperatures of 30―85 °C and glycerol concentrations of 0―50 mol %. The water activity is the only determinant of phase-transition point among CaSO4·2H2O (DH), α-CaSO4·0.5H2O (α-HH), and CaSO4 (AH) in glycerol-water solution. Accordingly, a phase-transition diagram was constructed as a function of temperature (0―140 °C) and glycerol concentration (0―50 mol %), which provided a thermodynamic preparation window of α-HH from DH. Controlling glycerol concentration and temperature within the window, direct transition of DH to α-HH can be regnlated. However, the window is apt to shrink as the operating time is shortened, indicating that its available profile is directed by transition kinetics ofDH to α-HH besides transition thermodynamics. Overall, the glycerol―water solution could act as a novel category of nonelectrolyte medium for α-HH preparation from DH. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267515