The composition of fluid inclusions in the H_2O-NaCl-CaCl_2 system has been generally graphically estimated using the melting temperatures of hydrohalite(T_(m-HH))and ice(T_(m-ice)).Here we present two equations that ...The composition of fluid inclusions in the H_2O-NaCl-CaCl_2 system has been generally graphically estimated using the melting temperatures of hydrohalite(T_(m-HH))and ice(T_(m-ice)).Here we present two equations that can be used to calculate the relative proportion of NaCl(i.e.,NaCl/[NaCl+CaCl_2],or X_(NaCl))and the total salinity( i.e.,NaC1 + CaC12,wt% )for fluid inclusions with ice as the last melting phase.X_(NaCl)can be calculated from T_(m-HH)using the following equation: y=(a+bx)^(-1/c) where y is X_(NaCl),x is T_(m-HH),a=0.33124402,b=-0.031518028,and c=0.22932736.In the cases where only T_(m-ice)is measured and T_(m-HH)is not known,T_(m-ice)can be used as the maximum possible TIn.nil to calculate the maximum value of X_(NaCl)using the above equation.In these cases,the following equation can be used to calculate the maximum total salinity: y=(a+bx+cx^2)^(-1) where y is salinity,x is T_(m-HH),a=0.057184817,b=0.00078565757,and c=5.7262766E-6.Because the isothems in the field of ice are sub-parallel to the NaCl-CaCl_2 binary side in the H20-NaC1-CaC12 ternary system,the errors in salinity calculation introduced by the above approximation are small(less than 2 wt% ).A Windows program for calculation of X_(NsCl)and salinity is available at: http://uregina.ca/~chiguox.展开更多
The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO...The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps. The first step occurs in the temperature range of 425-540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF reacts with CaO to produce RE2O3 and CaF2, and Ce2O3 is oxidized to CeO2. During this step, CaCO3 is formed at about 500 ℃. The second step takes place in the temperature range of 610-700 ℃, and the reactions are monazite decomposition into RE2O3, Ca5F(PO4)3 and Ca3(PO4)2 by CaO and CaF2. In this process, the decomposition ability is improved because CaO from CaCO3 decomposing has high chemical activity. In calcining process, the new formed Ca5F(PO4)3 restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.展开更多
Raman peaks of various hydrates in the H2O-NaCl-CaCl2 system have been previously identified,but a quantitative relationship between the Raman peaks and XNaCl(i.e.,NaCl/(NaCl+CaCl2)) has not been established,mainly du...Raman peaks of various hydrates in the H2O-NaCl-CaCl2 system have been previously identified,but a quantitative relationship between the Raman peaks and XNaCl(i.e.,NaCl/(NaCl+CaCl2)) has not been established,mainly due to the difficulty to freeze the solutions.This problem was solved by adding alumina powder to the solutions to facilitate nucleation of crystals.Cryogenic(-185oC) Raman spectroscopic studies of alumina-spiced solutions indicate that XNaCl is linearly correlated with the total peak area fraction of hydrohalite.Capsules of solutions made from silica capillary were prepared to simulate fluid inclusions.Most of these artificial fluid inclusions could not be totally frozen even at temperatures as low as-185 oC,and the total peak area fraction of hydrohalite is not correlated linearly with XNaCl.However,the degree of deviation(?XNaCl) from the linear correlation established earlier is related to the amount of residual solution,which is reflected by the ratio(r) of the baseline "bump" area,resulting from the interstitial unfrozen brine near 3435 cm-1,and the total hydrate peak area between 3350 and 3600 cm-1.A linear correlation between ?XNaCl and r is established to estimate XNaCl from cryogenic Raman spectroscopic analysis for fluid inclusions.展开更多
The influence of NaCl-CaCl2 on thermal decomposition of REPO4 (RE: Ce, La, Nd, Th) with CaO was studied. The heat decomposing process of REPO4 was tested with TG-DTA experiments. The results showed that the decomposit...The influence of NaCl-CaCl2 on thermal decomposition of REPO4 (RE: Ce, La, Nd, Th) with CaO was studied. The heat decomposing process of REPO4 was tested with TG-DTA experiments. The results showed that the decomposition temperature of REPO4 with CaO was reduced because of adding NaCl-CaCl2 mixture (NaCl:CaCl2=1:1). The influence of the addition of NaCl-CaCl2, roasting temperature and roasting time on decomposition ratio of REPO4 with CaO was studied. The results showed that the decomposition ratio of REPO4with CaO was 79% when the addition percentage of NaCl-CaCl2 was 10%, the roasting temperature was 750℃, and the roasting time was 1 h.展开更多
Previous cryogenic Raman spectroscopic analysis of H_2O-NaCl-CaCl_2 solutions has identified the Raman peaks of various hydrates of NaCl and CaCl_2,and established a linear relationship between Raman band intensity of...Previous cryogenic Raman spectroscopic analysis of H_2O-NaCl-CaCl_2 solutions has identified the Raman peaks of various hydrates of NaCl and CaCl_2,and established a linear relationship between Raman band intensity of the hydrates and the composition of the solution(NaCl/(NaCl+CaCl_2) molar ratio,or X_(NaC1)) using synthetic fluids,which created the opportunity to quantitatively determine the solute composition of aqueous fluid inclusions with cryogenic Raman spectroscopy.This paper aims to test the feasibility of this newly established method with natural fluid inclusions.Twenty-five fluid inclusions in quartz from various occurrences which show a high degree of freezing during the cooling processes were carefully chosen for cryogenic Raman analysis.X_(Na)Cl was calculated using their spectra and an equation established in a previous study.These inclusions were then analyzed with the thermal decrepitation-SEM-EDS method.The X_(NaCl) values estimated from the two methods show a 1:1 correlation,indicating that the new,non-destructive cryogenic Raman spectroscopic analysis method can indeed be used for fluid inclusion compositional study.展开更多
基金Project(2013CB632600)supported by the National Basic Research Program of ChinaProjects(21376251,21406233)supported by the National Natural Science Foundation of ChinaProject supported by the Fund of Hubei Zhenhua Chemical Co.,Ltd.,China
文摘The composition of fluid inclusions in the H_2O-NaCl-CaCl_2 system has been generally graphically estimated using the melting temperatures of hydrohalite(T_(m-HH))and ice(T_(m-ice)).Here we present two equations that can be used to calculate the relative proportion of NaCl(i.e.,NaCl/[NaCl+CaCl_2],or X_(NaCl))and the total salinity( i.e.,NaC1 + CaC12,wt% )for fluid inclusions with ice as the last melting phase.X_(NaCl)can be calculated from T_(m-HH)using the following equation: y=(a+bx)^(-1/c) where y is X_(NaCl),x is T_(m-HH),a=0.33124402,b=-0.031518028,and c=0.22932736.In the cases where only T_(m-ice)is measured and T_(m-HH)is not known,T_(m-ice)can be used as the maximum possible TIn.nil to calculate the maximum value of X_(NaCl)using the above equation.In these cases,the following equation can be used to calculate the maximum total salinity: y=(a+bx+cx^2)^(-1) where y is salinity,x is T_(m-HH),a=0.057184817,b=0.00078565757,and c=5.7262766E-6.Because the isothems in the field of ice are sub-parallel to the NaCl-CaCl_2 binary side in the H20-NaC1-CaC12 ternary system,the errors in salinity calculation introduced by the above approximation are small(less than 2 wt% ).A Windows program for calculation of X_(NsCl)and salinity is available at: http://uregina.ca/~chiguox.
基金Project(50574031) supported by the National Natural Science Foundation of ChinaProject(20030145015) supported by the Scientific Research Special Foundation of Doctoral Subject of Chinese University
文摘The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps. The first step occurs in the temperature range of 425-540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF reacts with CaO to produce RE2O3 and CaF2, and Ce2O3 is oxidized to CeO2. During this step, CaCO3 is formed at about 500 ℃. The second step takes place in the temperature range of 610-700 ℃, and the reactions are monazite decomposition into RE2O3, Ca5F(PO4)3 and Ca3(PO4)2 by CaO and CaF2. In this process, the decomposition ability is improved because CaO from CaCO3 decomposing has high chemical activity. In calcining process, the new formed Ca5F(PO4)3 restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.
基金supported by an NSERC-Discovery grant(to Chi)in part by the Knowledge Innovation Program of Chinese Academy of Sciences(SIDSSE201302)
文摘Raman peaks of various hydrates in the H2O-NaCl-CaCl2 system have been previously identified,but a quantitative relationship between the Raman peaks and XNaCl(i.e.,NaCl/(NaCl+CaCl2)) has not been established,mainly due to the difficulty to freeze the solutions.This problem was solved by adding alumina powder to the solutions to facilitate nucleation of crystals.Cryogenic(-185oC) Raman spectroscopic studies of alumina-spiced solutions indicate that XNaCl is linearly correlated with the total peak area fraction of hydrohalite.Capsules of solutions made from silica capillary were prepared to simulate fluid inclusions.Most of these artificial fluid inclusions could not be totally frozen even at temperatures as low as-185 oC,and the total peak area fraction of hydrohalite is not correlated linearly with XNaCl.However,the degree of deviation(?XNaCl) from the linear correlation established earlier is related to the amount of residual solution,which is reflected by the ratio(r) of the baseline "bump" area,resulting from the interstitial unfrozen brine near 3435 cm-1,and the total hydrate peak area between 3350 and 3600 cm-1.A linear correlation between ?XNaCl and r is established to estimate XNaCl from cryogenic Raman spectroscopic analysis for fluid inclusions.
基金Project supported by the National Natural Science Foundation of China (50574031)
文摘The influence of NaCl-CaCl2 on thermal decomposition of REPO4 (RE: Ce, La, Nd, Th) with CaO was studied. The heat decomposing process of REPO4 was tested with TG-DTA experiments. The results showed that the decomposition temperature of REPO4 with CaO was reduced because of adding NaCl-CaCl2 mixture (NaCl:CaCl2=1:1). The influence of the addition of NaCl-CaCl2, roasting temperature and roasting time on decomposition ratio of REPO4 with CaO was studied. The results showed that the decomposition ratio of REPO4with CaO was 79% when the addition percentage of NaCl-CaCl2 was 10%, the roasting temperature was 750℃, and the roasting time was 1 h.
文摘Previous cryogenic Raman spectroscopic analysis of H_2O-NaCl-CaCl_2 solutions has identified the Raman peaks of various hydrates of NaCl and CaCl_2,and established a linear relationship between Raman band intensity of the hydrates and the composition of the solution(NaCl/(NaCl+CaCl_2) molar ratio,or X_(NaC1)) using synthetic fluids,which created the opportunity to quantitatively determine the solute composition of aqueous fluid inclusions with cryogenic Raman spectroscopy.This paper aims to test the feasibility of this newly established method with natural fluid inclusions.Twenty-five fluid inclusions in quartz from various occurrences which show a high degree of freezing during the cooling processes were carefully chosen for cryogenic Raman analysis.X_(Na)Cl was calculated using their spectra and an equation established in a previous study.These inclusions were then analyzed with the thermal decrepitation-SEM-EDS method.The X_(NaCl) values estimated from the two methods show a 1:1 correlation,indicating that the new,non-destructive cryogenic Raman spectroscopic analysis method can indeed be used for fluid inclusion compositional study.
