1 Introduction Lithium resources are widely distributed in the oilfield brine from the Nanyishan district in the Qaidam Basin(Fan et al.,2007).The investigation of the thermodynamics and phase diagram of the brine sys...1 Introduction Lithium resources are widely distributed in the oilfield brine from the Nanyishan district in the Qaidam Basin(Fan et al.,2007).The investigation of the thermodynamics and phase diagram of the brine system is valuable in providing the theoretic foundation and scientific guidance in the comprehensive exploitation of the mixture salts effectively.Comprehensive展开更多
Saline soils are significantly affected by water-salt phase changes,evaporation,and groundwater during seasonal freezing and thawing.For the study of physical and mechanical properties of saline soils,solubility is an...Saline soils are significantly affected by water-salt phase changes,evaporation,and groundwater during seasonal freezing and thawing.For the study of physical and mechanical properties of saline soils,solubility is an important indicator that varies with temperature.However,there have been very limited computational studies on solubility at low temperatures.The model for calculating the solubility of Na_(2)SO_(4)-NaCl-H_(2)O ternary system under low temperature conditions was constructed in this paper,based on the Pitzer and BET models.Improvements were made to the parametersФandγin the Pitzer model,while improvements were made to the parameters c,r,and aw in the BET model.The solubility changes within the range of 273.15 K–373.15 K were calculated and validated by combining them with indoor experiments.It was found that both the improved Pitzer model and BET model accurately predicted relative equilibrium solubility data of the Na_(2)SO_(4)-NaCl-H_(2)O ternary system at temperatures ranging from 273.15 K to 373.15 K.Additionally,compared with the Pitzer model,the BET model had advantages such as easy parameter acquisition and wider application range.The findings from this research hold great significance for understanding the process and patterns of salt analysis during soil freeze-thaw cycles as well as providing a scientific foundation for further comprehension of phase change laws and physical properties related to saline soils.展开更多
The geochemical simulation of the formation of brine and salt minerals based on Pitzer model was made in Caka Salt Lake. The evolution of the mixed surface-water and the mineral sequences were calculated and compared ...The geochemical simulation of the formation of brine and salt minerals based on Pitzer model was made in Caka Salt Lake. The evolution of the mixed surface-water and the mineral sequences were calculated and compared with the hydrochemical compositions of the brine and the salt minerals of the deposit in Caka Salt Lake. The results show that the formation temperature of the lake is between 0°C and 5°C, which is well identical with other studies. The mixing of salt-karst water with the surface waters, neglected by the former researchers, is very important to the formation of the lake, indicating that the initial waters resulting in the formation of the lake are multi-source. It is the first time to use Pitzer model in China for making geochemical simulation of the formation and evolution of inland salt lake and satisfactory results have been achieved.展开更多
The thermodynamic properties of the most important NaOH-NaAI（OH）4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissol...The thermodynamic properties of the most important NaOH-NaAI（OH）4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI（OH）4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β（0）（NaAl（OH）4）、β（1）（NaAl（OH）4）和CΦ（NaAl（OH）4）,Al（OH）4 for NaAI（OH）4, the binary mixing parameter of θ（OH-Al（OH）4-） with OH-, and the ternary mixing parameter of ψ（Na＋OH-Al（OH）4-） for AI（OH）4- with OH- and Na＋ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.展开更多
Aiming at the problems of complex process and high cost in the production of potassium bromide at present,the solubility data and the phase diagram of the quaternary system KBr-MgBr_(2)-K_(2)SO_(4)-MgSO_(4)-H_(2)O at ...Aiming at the problems of complex process and high cost in the production of potassium bromide at present,the solubility data and the phase diagram of the quaternary system KBr-MgBr_(2)-K_(2)SO_(4)-MgSO_(4)-H_(2)O at 298.15 K were studied using the isothermal dissolution equilibrium method.The results showed that there are eight invariant points,sixteen univariant curves,and nine crystallization regions in the phase diagram which is complex and contains two double salts(K_(2)SO_(4)·MgSO_(4)·6H_(2)O and KBr·MgBr_(2)·6H_(2)O)and a metastable phase(MgSO_(4)·5H_(2)O).On the basis of the Pitzer model and HW model,the solubilities of the quaternary system were calculated,with which the corresponding phase diagram was plotted.By comparison,the evaluated phase diagram is in accordance with the measured one.Through analysis,the phase diagrams of the quaternary system at(298.15 and 323.15)K were combined to put forward a process to separate KBr from the system by evaporation and crystallization,which realized the full circulation of the mother solution.展开更多
Solid solution hinders the extraction of bromine resources from bittern.To separate chlorine-brominebased solid solution in bittern tail solution,the solubilities of the quaternary system KCl-KBr-NaCl-NaBr-H_(2)O and ...Solid solution hinders the extraction of bromine resources from bittern.To separate chlorine-brominebased solid solution in bittern tail solution,the solubilities of the quaternary system KCl-KBr-NaCl-NaBr-H_(2)O and its ternary subsystem NaBr-KBr-H_(2)O at 333.15 K were determined by the isothermal dissolution method,and the corresponding phase diagrams were conducted.An improved model was employed to predict the solubilities of the quaternary system KCl-KBr-NaCl-NaBr-H_(2)O at 333.15 K.The calculated results coincide with the experimental values,implying that the prediction method is feasible.A closed loop crystallization process for the separation of chlorine-bromine-based solid solution in bittern tail solution was proposed and NaBr was obtained with a purity of 98.23%.展开更多
As an important strategic reserve resource,the comprehensive development and utilization of Nanyishan oil-gas field brine will bring great economic and social value.Here,according to the composition characteristics of...As an important strategic reserve resource,the comprehensive development and utilization of Nanyishan oil-gas field brine will bring great economic and social value.Here,according to the composition characteristics of this oil-gas field brine being rich in lithium,potassium and strontium,the solid-liquid stable phase equilibria and phase diagrams of Li-containing quaternary system(LiBr-MgBr_(2)-SrBr_(2)-H_(2)O)and two quinary systems(LiBr-NaBr-MgBr_(2)-SrBr_(2)-H_(2)O and LiBr-KBr-MgBr_(2)-SrBr_(2)-H_(2)O)were studied at 298.15 K.Based on the results of phase equilibrium experimental research,the phase equilibrium relationship and crystallization-dissolution behavior of each component in liquid phase were revealed theoretically,and the changing trend was summarized.Using theoretical model of Pitzer electrolyte solution,the relevant interaction parameters of mixed ions at 298.15 K were obtained by fitting experimental data,and the solubility reaching equilibrium of various salts in above systems was calculated,and the experimental results were verified.The research results of this paper lay an important foundation for further theoretical study of multi-temperature phase equilibrium and thermodynamic properties of complex brine system in the later stage.Meanwhile,it provides basic thermodynamic data and theoretical guidance for the rational development and comprehensive utilization of this oil-gas field brine resources.展开更多
基金Supported by the NNSFCs (21276194 and 21306136)the Key Pillar Program of Tianjin Municipal S&T (11ZCKGX02800)the Specialised Research Fund for the Doctoral Program of Chinese Higher Education (20101208110003)
文摘1 Introduction Lithium resources are widely distributed in the oilfield brine from the Nanyishan district in the Qaidam Basin(Fan et al.,2007).The investigation of the thermodynamics and phase diagram of the brine system is valuable in providing the theoretic foundation and scientific guidance in the comprehensive exploitation of the mixture salts effectively.Comprehensive
基金supported by the National key research&development program of China(Grant no.2021YFD1900600)the National Natural Science Foundation of Ningxia(2023AAC05014)+1 种基金the Ningxia Key Research and Development Program(Special Talents)(2023BSB03021)the Scientific Research Program of University of Ningxia Education Department(NYG2024049)。
文摘Saline soils are significantly affected by water-salt phase changes,evaporation,and groundwater during seasonal freezing and thawing.For the study of physical and mechanical properties of saline soils,solubility is an important indicator that varies with temperature.However,there have been very limited computational studies on solubility at low temperatures.The model for calculating the solubility of Na_(2)SO_(4)-NaCl-H_(2)O ternary system under low temperature conditions was constructed in this paper,based on the Pitzer and BET models.Improvements were made to the parametersФandγin the Pitzer model,while improvements were made to the parameters c,r,and aw in the BET model.The solubility changes within the range of 273.15 K–373.15 K were calculated and validated by combining them with indoor experiments.It was found that both the improved Pitzer model and BET model accurately predicted relative equilibrium solubility data of the Na_(2)SO_(4)-NaCl-H_(2)O ternary system at temperatures ranging from 273.15 K to 373.15 K.Additionally,compared with the Pitzer model,the BET model had advantages such as easy parameter acquisition and wider application range.The findings from this research hold great significance for understanding the process and patterns of salt analysis during soil freeze-thaw cycles as well as providing a scientific foundation for further comprehension of phase change laws and physical properties related to saline soils.
文摘The geochemical simulation of the formation of brine and salt minerals based on Pitzer model was made in Caka Salt Lake. The evolution of the mixed surface-water and the mineral sequences were calculated and compared with the hydrochemical compositions of the brine and the salt minerals of the deposit in Caka Salt Lake. The results show that the formation temperature of the lake is between 0°C and 5°C, which is well identical with other studies. The mixing of salt-karst water with the surface waters, neglected by the former researchers, is very important to the formation of the lake, indicating that the initial waters resulting in the formation of the lake are multi-source. It is the first time to use Pitzer model in China for making geochemical simulation of the formation and evolution of inland salt lake and satisfactory results have been achieved.
基金Project (2005CB6237) supported by the National Basic Research Program of China
文摘The thermodynamic properties of the most important NaOH-NaAI（OH）4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI（OH）4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β（0）（NaAl（OH）4）、β（1）（NaAl（OH）4）和CΦ（NaAl（OH）4）,Al（OH）4 for NaAI（OH）4, the binary mixing parameter of θ（OH-Al（OH）4-） with OH-, and the ternary mixing parameter of ψ（Na＋OH-Al（OH）4-） for AI（OH）4- with OH- and Na＋ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.
基金supported by the National Natural Science Foundation of China (22008049 and 22478095)Hebei Provincial Key Research Projects (22374101D)+3 种基金Central Guidance Project for Local Science and Technology Development from S&T Program of Hebei (246Z1009G)Special Proof-of-concept Project on Basic Research from S&T Program of Hebei (E2024402143)Science and Technology Project of Hebei Education Department (CXY2023004)Hebei University of Engineering Doctoral Scientific Research Start-up Foundation (SJ2401002210).
文摘Aiming at the problems of complex process and high cost in the production of potassium bromide at present,the solubility data and the phase diagram of the quaternary system KBr-MgBr_(2)-K_(2)SO_(4)-MgSO_(4)-H_(2)O at 298.15 K were studied using the isothermal dissolution equilibrium method.The results showed that there are eight invariant points,sixteen univariant curves,and nine crystallization regions in the phase diagram which is complex and contains two double salts(K_(2)SO_(4)·MgSO_(4)·6H_(2)O and KBr·MgBr_(2)·6H_(2)O)and a metastable phase(MgSO_(4)·5H_(2)O).On the basis of the Pitzer model and HW model,the solubilities of the quaternary system were calculated,with which the corresponding phase diagram was plotted.By comparison,the evaluated phase diagram is in accordance with the measured one.Through analysis,the phase diagrams of the quaternary system at(298.15 and 323.15)K were combined to put forward a process to separate KBr from the system by evaporation and crystallization,which realized the full circulation of the mother solution.
基金supported by the National Natural Science Foundation of China(22478095 and 22008049)Hebei Provincial Key Research Projects(22374101D)+4 种基金Scientific Research Projects of Colleges and University in Hebei Province(QN2023007)Central Guidance Project for Local Science and Technology Development from S&T Program of Hebei(246Z1009G)Special Proof-of-concept Project on Basic Research from S&T Program of Hebei(E2024402143)Science and Technology Project of Hebei Education Department(CXY2023004)Hebei University of Engineering Doctoral Scientific Research Start-up Foundation(SJ2401002210).
文摘Solid solution hinders the extraction of bromine resources from bittern.To separate chlorine-brominebased solid solution in bittern tail solution,the solubilities of the quaternary system KCl-KBr-NaCl-NaBr-H_(2)O and its ternary subsystem NaBr-KBr-H_(2)O at 333.15 K were determined by the isothermal dissolution method,and the corresponding phase diagrams were conducted.An improved model was employed to predict the solubilities of the quaternary system KCl-KBr-NaCl-NaBr-H_(2)O at 333.15 K.The calculated results coincide with the experimental values,implying that the prediction method is feasible.A closed loop crystallization process for the separation of chlorine-bromine-based solid solution in bittern tail solution was proposed and NaBr was obtained with a purity of 98.23%.
基金supported by the Natural Science Foundation of Qinghai Province(2024-ZJ-901).
文摘As an important strategic reserve resource,the comprehensive development and utilization of Nanyishan oil-gas field brine will bring great economic and social value.Here,according to the composition characteristics of this oil-gas field brine being rich in lithium,potassium and strontium,the solid-liquid stable phase equilibria and phase diagrams of Li-containing quaternary system(LiBr-MgBr_(2)-SrBr_(2)-H_(2)O)and two quinary systems(LiBr-NaBr-MgBr_(2)-SrBr_(2)-H_(2)O and LiBr-KBr-MgBr_(2)-SrBr_(2)-H_(2)O)were studied at 298.15 K.Based on the results of phase equilibrium experimental research,the phase equilibrium relationship and crystallization-dissolution behavior of each component in liquid phase were revealed theoretically,and the changing trend was summarized.Using theoretical model of Pitzer electrolyte solution,the relevant interaction parameters of mixed ions at 298.15 K were obtained by fitting experimental data,and the solubility reaching equilibrium of various salts in above systems was calculated,and the experimental results were verified.The research results of this paper lay an important foundation for further theoretical study of multi-temperature phase equilibrium and thermodynamic properties of complex brine system in the later stage.Meanwhile,it provides basic thermodynamic data and theoretical guidance for the rational development and comprehensive utilization of this oil-gas field brine resources.
