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Titolo:
CHEMISTRY OF BORATE IN SALT LAKE BRINE .1 7. STUDY ON LIQUID-SOLID PHASE-DIAGRAM OF THERMODYNAMIC NONEQUILIBRIUM OF MGO-B2O3-28-PERCENT-MGCL2-H2O SYSTEM AT 20-DEGREES-C
Autore:
GAO SY; YAO ZL; XIA SP;
Indirizzi:
ACAD SINICA,QINGHAI INST SALT LAKES XINING 810008 PEOPLES R CHINA
Titolo Testata:
Huaxue xuebao
fascicolo: 1, volume: 52, anno: 1994,
pagine: 10 - 22
SICI:
0567-7351(1994)52:1<10:COBISL>2.0.ZU;2-5
Fonte:
ISI
Lingua:
CHI
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
2
Recensione:
Indirizzi per estratti:
Citazione:
S.Y. Gao et al., "CHEMISTRY OF BORATE IN SALT LAKE BRINE .1 7. STUDY ON LIQUID-SOLID PHASE-DIAGRAM OF THERMODYNAMIC NONEQUILIBRIUM OF MGO-B2O3-28-PERCENT-MGCL2-H2O SYSTEM AT 20-DEGREES-C", Huaxue xuebao, 52(1), 1994, pp. 10-22

Abstract

The MgO-B2O3-MgCl2-H2O supersaturated solutions containing 28 % MgCl2and different mole ratio MgO:B2O3 were prepared and kept at 20-degrees-C. The crystallization processes of Mg borates from the solutions have been studied with the kinetic method. When a solid began to crystallize out from the solution, the solution samples were taken at different time for determing their densities, pH values and compositions until the density did not change basically. Finally, the solid phase was seperated, washed, dryed at room temperature and identified by IR spectra, powder X-ray diffraction, thermal analysis and chemical analysis. With the aid of simplex method and digital integration as well as Runge-Kutta digital solution of differential equation system, we fitted the experimental data and evaluated the kinetic parameters of the chosenmodels with computer. The crystallization kinetic equations have beengiven. The calculated results show that when MgO:B2O3 in initial solutions are 1.5:1, 1:2, 1:4, 1:6 and 1:9, the mechanism of crystallization are polynuclear layer controlled growth. When MgO:B2O3 are 3: 1 and2:1, the mechanism of crystallization are mononuclear layer controlled growth. We also disscussed the crystallization reaction processes. In this paper, we obtain the liquid-solid phase diagram of supersaturated solutions of MgO-B2O3-28%MgCl2-H2O system at 20-degrees-C for the first time and call it a phase diagram of thermodynamic non-equilibriumstate. There are six solid phases in the diagram. They are H3BO3, MgO.3B2O3.7.5H2O, MgO.3B2O3.7H2O, 2MgO.2B2O3. MgCl2.14H2O, 3Mg(OH)2.MgCl2.8H2O and 5Mg(OH)2.MgCl2.8H2O respectively.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 06:14:06