The thermal equation of state of a natural kyanite has been investigated with a DIA-type,cubic-anvil apparatus(SAM85)combined with an energy-dispersive synchrotron X-ray radiation technique up to 8.55 GPa and 1273 K.N...The thermal equation of state of a natural kyanite has been investigated with a DIA-type,cubic-anvil apparatus(SAM85)combined with an energy-dispersive synchrotron X-ray radiation technique up to 8.55 GPa and 1273 K.No phase transition was observed in the studied pressure-temperature(P-T)range.The Le Bail full profile refinement technique was used to derive the unit-cell parameters.By fixing the bulk modulus K 0 as 196 GPa and its pressure derivative K0 as 4,our P-V(volume)-T data were fitted to the high temperature BircheMurnaghan equation of state.The obtained parameters for the kyanite are:V_(0)=294.05(9)Å^(3),a=2.53(11)×10^(-5)K^(-1) and(K/T)P=-0.021(8)GPa∙K^(-1).These parameters have been combined with other experimentally-measured thermodynamic data for the relevant phases to calculate the P-T locus of the reaction kyanite¼stishoviteþcorundum.With this thermodynamically constrained phase boundary,previous high-pressure phase equi-librium experimental studies with the multi-anvil press have been evaluated.展开更多
Coesite inclusions are found in kyanite from the Lanshantoueclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metam...Coesite inclusions are found in kyanite from the Lanshantoueclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A-subduction induced by strong compression of the Yellow Sea terrane to the Jiaodong-northereastem Jiangsu terrane during the interaction of the Eurasian plate and Palaeo-Pacific plate in the Indosinian. It stretches about 350 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B and C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The MgO, CaO and FeO contents in garnet and pyroxene show regular variation from the core to the rim, which reveals the PTt paths of progressive metamorphism during the Early Mesozoic (240-200 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.展开更多
Kyanite is an important and slow-dissolving mineral. Earlier work has measured its dissolution rate at high temperature and acidic pH, but experimental measurements at low temperature and near neutral p H were lacking...Kyanite is an important and slow-dissolving mineral. Earlier work has measured its dissolution rate at high temperature and acidic pH, but experimental measurements at low temperature and near neutral p H were lacking. The rate equation by Palandri and Kharaka(A compilation of rate parameters of water–mineral interaction kinetics for application to geochemical modeling. US Geological Survey, Open File Report 2004-1068, 2004) indicates that the rate of kyanite dissolution at room temperature and near neutral pH is on the order of 10^-17 mol m^-2 s^-1, orders of magnitudes slower than most common silicate minerals such as albite and quartz. This study used an externallystirred mixed-flow reactor, which allows high solid:solution ratios, to measure the dissolution rate of kyanite at 0–22 ℃ and pH of 3.5–7.5. The measured dissolution rate of kyanite is 4.6–7.6 9 10-13 mol m^-2 s^-1 at 22℃, and the apparent activation energy is 73.5 kJ mol^-1. This dissolution rate is close to the rate of quartz dissolution and four orders of magnitude faster than the prediction by rate equation of Palandri and Kharaka(2004).Based on our new experimental data, we recommend the following rate equation for modeling the dissolution of kyanite at ambient temperatures.r=ke(-Ea)/R(1/T-1/(298.15))where k = 5.08 9 10-13 mol m^-2 s^-1, and Ea= 73.5 kJ mol^-1. Review of literature data(Carroll in The dissolution behavior of corundum, kaolinite, and andalusite: a surface complex reaction model for the dissolution of aluminosilicate minerals in diagenetic and weathering environs. Dissertation, Northwestern University, 1989) led to a recommended rate equation for andalusite as for T = 25℃ and pH = 2–10:r=k1aH+^n1+k2+k3aH^+^n3where k1= 4.04 9 10^-10 mol m^-2 s^-1, k2= 7.95×10^-10 mol m^-2 s^-1, k3= 1.01×10^-17 mol m^-2 s^-1, n1= 1.2 and n3=-0.6.展开更多
Sintered mullite is prepared by kyanite powder with Al_2O_3 content of 45% and 50%(Yinshan, Nanyang City, China),and the industrial alumina is added to control the chemical composition. The different series of sintere...Sintered mullite is prepared by kyanite powder with Al_2O_3 content of 45% and 50%(Yinshan, Nanyang City, China),and the industrial alumina is added to control the chemical composition. The different series of sintered mullite according to the Al_2O_3 content(45%-70%) are designed. The raw materials are mixed and compacted, and then sintered at different temperatures. Physical properties, phase composition, microstructure and refractoriness under load of the synthesized samples are characterized by physical property test, XRD, SEM and RUL test, in order to confirm the quality of sintering and the relationship between temperature and mullitization reaction. The results show that the sintered mullite from low-medium grade kyanite has well developed mullite crystals and a continuous staggered network structure is formed, which has a significant contribution to increasing the high temperature performance of mullite.展开更多
To improve the physical properties, a series of experiments have been camed out to produce calcium-bearing mullite thermal-insulating refractories by using kyanite as major raw materials. The experiments were carried ...To improve the physical properties, a series of experiments have been camed out to produce calcium-bearing mullite thermal-insulating refractories by using kyanite as major raw materials. The experiments were carried out by a foaming technique and using white cement as a combing agent. The results show that the calcium-bearing mullite refractory has much better physical properhes than traditional clay refractory and high-alumina refractory.展开更多
Five lightweight mullite castables were prepared using the lightweight mullite aggregate(M45A) with narrow particle size distribution and spherical shape,mullite powder(M45P),kyanite powder,microsilica and Secar 71 ce...Five lightweight mullite castables were prepared using the lightweight mullite aggregate(M45A) with narrow particle size distribution and spherical shape,mullite powder(M45P),kyanite powder,microsilica and Secar 71 cement as raw materials. After the specimens fired at 1100 ℃,1200 ℃ and 1300 ℃ for 3h,respectively,the effects of kyanite contents( 8%,10%,12%,14%,16% by mass) on the physical properties,phase composition and microstructures were investigated through an X-ray diffractometer( XRD),a scanning election microscopy( SEM) and a microscopy measurement method,etc. The results show that,for the specimens fired at 1300 ℃ with the kyanite content from 8%to16%, the bulk densities and apparent porosities change little,but the cold modulus of rupture and the crushing strengths decrease significantly,and the linear change rates increase from-0.87% to 0.64%. The most apposite mode is the specimen containing 12% kyanite fired at 1300 ℃, which has a high crushing strength of 29.3 MPa,a low linear change of 0.18%,an apparent porosity of 36.8% and a bulk density of 1.73 g/cm^3.展开更多
The use of waste materials to produce engineering components is currently attracting so much interest due to their low cost, availability and environmental impact. In this study, coconut shell ash (CSA) and kyanite pa...The use of waste materials to produce engineering components is currently attracting so much interest due to their low cost, availability and environmental impact. In this study, coconut shell ash (CSA) and kyanite particles (KP) produced from coconut shells and kyanite mineral respectively were characterized. X-ray Florence (XRF), X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze the oxide compositions, crystalline phases and microstructures of CSA and KP. The XRF analysis revealed major oxides in CSA and KP as SiO2 and Fe2O3;and Al2O3 and SiO2 respectively. The XRD analysis revealed the presence of Quartz, Hematite, Andradite and Gaultite phases at major peaks in diffractogram of CSA;and Quartz and Beryl phases at major peaks in the diffractogram of KP. The crystallite sizes of the quartz phases in CSA and KP at diffraction angle of 26.72°C and 20.91°C were determined as 638.28 Åand 789.38 Årespectively. From the SEM image of CSA, it was observed that particles of different sizes are present in the microstructure of CSA. The average size of the particles in the microstructure of CSA is 26.24 μm. A similar result was observed in the SEM image of KP and average size of the particles is 3.074 μm. Also, the energy dispersive X-ray (EDX) spectrums of CSA and KP revealed the presence of many elements with calcium as the major element in CSA and Aluminium as major element in KP. The presence of the crystalline phases in CSA (SiO2, Al2O3, andradite, gaultite and hematite) and KP (SiO2 and Al2O3) will make them good strengthening materials for the production of Aluminium based composites that can be used in applications where a good combination of strength and wear characteristics is a basic requirement like brake disc.展开更多
As a minor phase, kyanite has been repeatedly shown to have experienced ultrahigh pressure(UHP) metamorphism together with its host eclogites. Thus, it could play some role in transporting water into the deep earth. H...As a minor phase, kyanite has been repeatedly shown to have experienced ultrahigh pressure(UHP) metamorphism together with its host eclogites. Thus, it could play some role in transporting water into the deep earth. Here we present a detailed investigation of water concentrations of kyanite, and for reference, of garnet and omphacite from four Maobei eclogites in the Sulu orogenic belt, eastern China. Fourier transform infrared(FTIR) measurements show that kyanites, garnets, and omphacites all have distinct hydroxyl absorption bands due to OH groups bound in their crystal structure. The FTIR profile analyses on ten grains from different samples reveal a homogeneous distribution of water across kyanite, suggesting insignificant water loss during exhumation. The calculated water concentrations in kyanite(21 wt ppm–41 wt ppm) are comparable to those reported previously for kyanite from various geological occurrences when using the most recent calibration. They are however much lower compared with those in garnet(46 wt ppm–83 wt ppm) and omphacite(302 wt ppm–548 wt ppm) from the Maobei eclogites. This implies that kyanite is not a major water carrier in eclogites considering its low volume fraction and contributes negligibly to transport water into the deep mantle accompanying subducted oceanic crust until its possible transformation to AlSiO_3 H.展开更多
Corundum(ruby-sapphire) is known to have formed in situ within Archean metamorphic rocks at several localities in the North Atlantic Craton of Greenland. Here we present two case studies for such occurrences:(1) Manii...Corundum(ruby-sapphire) is known to have formed in situ within Archean metamorphic rocks at several localities in the North Atlantic Craton of Greenland. Here we present two case studies for such occurrences:(1) Maniitsoq region(Kangerdluarssuk), where kyanite paragneiss hosts ruby corundum, and(2)Nuuk region(Stor?), where sillimanite gneiss hosts ruby corundum. At both occurrences, ultramafic rocks(amphibole-peridotite) are in direct contact with the ruby-bearing zones, which have been transformed to mica schist by metasomatic reactions. The bulk-rock geochemistry of the ruby-bearing rocks is consistent with significant depletion of SiO_2 in combination with addition of Al_2O_3, MgO, K_2O,Th and Sr relative to an assumed aluminous precursor metapelite. Phase equilibria modelling supports ruby genesis from the breakdown of sillimanite and kyanite at elevated temperatures due to the removal of SiO_2. The juxtaposition of relatively silica-and aluminum-rich metasedimentary rocks with low silica ultramafic rocks established a chemical potential gradient that leached/mobilized SiO_2 allowing corundum to stabilize in the former rocks. Furthermore, addition of Al_2O_3 via a metasomatic reaction is required, because Al/Ti is fractionated between the aluminous precursor metapelites and the resulting corundum-bearing mica schist. We propose that Al was mobilized either by complexation with hydroxide at alkaline conditions, or that Al was transported as K-Al-Si-O polymers at deep crustal levels.The three main exploration vectors for corundum within Archean greenstone belts are:(1) amphiboliteto granulite-facies metamorphic conditions,(2) the juxtaposition of ultramafic rocks and aluminous metapelite, and(3) mica-rich reactions zones at their interface.展开更多
基金This work is financially supported by the Natural Science Foundation of China(Grant No.41273072)by the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB18030602).
文摘The thermal equation of state of a natural kyanite has been investigated with a DIA-type,cubic-anvil apparatus(SAM85)combined with an energy-dispersive synchrotron X-ray radiation technique up to 8.55 GPa and 1273 K.No phase transition was observed in the studied pressure-temperature(P-T)range.The Le Bail full profile refinement technique was used to derive the unit-cell parameters.By fixing the bulk modulus K 0 as 196 GPa and its pressure derivative K0 as 4,our P-V(volume)-T data were fitted to the high temperature BircheMurnaghan equation of state.The obtained parameters for the kyanite are:V_(0)=294.05(9)Å^(3),a=2.53(11)×10^(-5)K^(-1) and(K/T)P=-0.021(8)GPa∙K^(-1).These parameters have been combined with other experimentally-measured thermodynamic data for the relevant phases to calculate the P-T locus of the reaction kyanite¼stishoviteþcorundum.With this thermodynamically constrained phase boundary,previous high-pressure phase equi-librium experimental studies with the multi-anvil press have been evaluated.
文摘Coesite inclusions are found in kyanite from the Lanshantoueclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A-subduction induced by strong compression of the Yellow Sea terrane to the Jiaodong-northereastem Jiangsu terrane during the interaction of the Eurasian plate and Palaeo-Pacific plate in the Indosinian. It stretches about 350 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B and C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The MgO, CaO and FeO contents in garnet and pyroxene show regular variation from the core to the rim, which reveals the PTt paths of progressive metamorphism during the Early Mesozoic (240-200 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.
基金provided by the U.S. NSF Grant EAR-1225733 to Dr. Chen Zhu, and Indiana University
文摘Kyanite is an important and slow-dissolving mineral. Earlier work has measured its dissolution rate at high temperature and acidic pH, but experimental measurements at low temperature and near neutral p H were lacking. The rate equation by Palandri and Kharaka(A compilation of rate parameters of water–mineral interaction kinetics for application to geochemical modeling. US Geological Survey, Open File Report 2004-1068, 2004) indicates that the rate of kyanite dissolution at room temperature and near neutral pH is on the order of 10^-17 mol m^-2 s^-1, orders of magnitudes slower than most common silicate minerals such as albite and quartz. This study used an externallystirred mixed-flow reactor, which allows high solid:solution ratios, to measure the dissolution rate of kyanite at 0–22 ℃ and pH of 3.5–7.5. The measured dissolution rate of kyanite is 4.6–7.6 9 10-13 mol m^-2 s^-1 at 22℃, and the apparent activation energy is 73.5 kJ mol^-1. This dissolution rate is close to the rate of quartz dissolution and four orders of magnitude faster than the prediction by rate equation of Palandri and Kharaka(2004).Based on our new experimental data, we recommend the following rate equation for modeling the dissolution of kyanite at ambient temperatures.r=ke(-Ea)/R(1/T-1/(298.15))where k = 5.08 9 10-13 mol m^-2 s^-1, and Ea= 73.5 kJ mol^-1. Review of literature data(Carroll in The dissolution behavior of corundum, kaolinite, and andalusite: a surface complex reaction model for the dissolution of aluminosilicate minerals in diagenetic and weathering environs. Dissertation, Northwestern University, 1989) led to a recommended rate equation for andalusite as for T = 25℃ and pH = 2–10:r=k1aH+^n1+k2+k3aH^+^n3where k1= 4.04 9 10^-10 mol m^-2 s^-1, k2= 7.95×10^-10 mol m^-2 s^-1, k3= 1.01×10^-17 mol m^-2 s^-1, n1= 1.2 and n3=-0.6.
文摘Sintered mullite is prepared by kyanite powder with Al_2O_3 content of 45% and 50%(Yinshan, Nanyang City, China),and the industrial alumina is added to control the chemical composition. The different series of sintered mullite according to the Al_2O_3 content(45%-70%) are designed. The raw materials are mixed and compacted, and then sintered at different temperatures. Physical properties, phase composition, microstructure and refractoriness under load of the synthesized samples are characterized by physical property test, XRD, SEM and RUL test, in order to confirm the quality of sintering and the relationship between temperature and mullitization reaction. The results show that the sintered mullite from low-medium grade kyanite has well developed mullite crystals and a continuous staggered network structure is formed, which has a significant contribution to increasing the high temperature performance of mullite.
文摘To improve the physical properties, a series of experiments have been camed out to produce calcium-bearing mullite thermal-insulating refractories by using kyanite as major raw materials. The experiments were carried out by a foaming technique and using white cement as a combing agent. The results show that the calcium-bearing mullite refractory has much better physical properhes than traditional clay refractory and high-alumina refractory.
文摘Five lightweight mullite castables were prepared using the lightweight mullite aggregate(M45A) with narrow particle size distribution and spherical shape,mullite powder(M45P),kyanite powder,microsilica and Secar 71 cement as raw materials. After the specimens fired at 1100 ℃,1200 ℃ and 1300 ℃ for 3h,respectively,the effects of kyanite contents( 8%,10%,12%,14%,16% by mass) on the physical properties,phase composition and microstructures were investigated through an X-ray diffractometer( XRD),a scanning election microscopy( SEM) and a microscopy measurement method,etc. The results show that,for the specimens fired at 1300 ℃ with the kyanite content from 8%to16%, the bulk densities and apparent porosities change little,but the cold modulus of rupture and the crushing strengths decrease significantly,and the linear change rates increase from-0.87% to 0.64%. The most apposite mode is the specimen containing 12% kyanite fired at 1300 ℃, which has a high crushing strength of 29.3 MPa,a low linear change of 0.18%,an apparent porosity of 36.8% and a bulk density of 1.73 g/cm^3.
文摘The use of waste materials to produce engineering components is currently attracting so much interest due to their low cost, availability and environmental impact. In this study, coconut shell ash (CSA) and kyanite particles (KP) produced from coconut shells and kyanite mineral respectively were characterized. X-ray Florence (XRF), X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze the oxide compositions, crystalline phases and microstructures of CSA and KP. The XRF analysis revealed major oxides in CSA and KP as SiO2 and Fe2O3;and Al2O3 and SiO2 respectively. The XRD analysis revealed the presence of Quartz, Hematite, Andradite and Gaultite phases at major peaks in diffractogram of CSA;and Quartz and Beryl phases at major peaks in the diffractogram of KP. The crystallite sizes of the quartz phases in CSA and KP at diffraction angle of 26.72°C and 20.91°C were determined as 638.28 Åand 789.38 Årespectively. From the SEM image of CSA, it was observed that particles of different sizes are present in the microstructure of CSA. The average size of the particles in the microstructure of CSA is 26.24 μm. A similar result was observed in the SEM image of KP and average size of the particles is 3.074 μm. Also, the energy dispersive X-ray (EDX) spectrums of CSA and KP revealed the presence of many elements with calcium as the major element in CSA and Aluminium as major element in KP. The presence of the crystalline phases in CSA (SiO2, Al2O3, andradite, gaultite and hematite) and KP (SiO2 and Al2O3) will make them good strengthening materials for the production of Aluminium based composites that can be used in applications where a good combination of strength and wear characteristics is a basic requirement like brake disc.
基金supported by the National Natural Science Foundation of China (Nos. 41372224 and 41590623)
文摘As a minor phase, kyanite has been repeatedly shown to have experienced ultrahigh pressure(UHP) metamorphism together with its host eclogites. Thus, it could play some role in transporting water into the deep earth. Here we present a detailed investigation of water concentrations of kyanite, and for reference, of garnet and omphacite from four Maobei eclogites in the Sulu orogenic belt, eastern China. Fourier transform infrared(FTIR) measurements show that kyanites, garnets, and omphacites all have distinct hydroxyl absorption bands due to OH groups bound in their crystal structure. The FTIR profile analyses on ten grains from different samples reveal a homogeneous distribution of water across kyanite, suggesting insignificant water loss during exhumation. The calculated water concentrations in kyanite(21 wt ppm–41 wt ppm) are comparable to those reported previously for kyanite from various geological occurrences when using the most recent calibration. They are however much lower compared with those in garnet(46 wt ppm–83 wt ppm) and omphacite(302 wt ppm–548 wt ppm) from the Maobei eclogites. This implies that kyanite is not a major water carrier in eclogites considering its low volume fraction and contributes negligibly to transport water into the deep mantle accompanying subducted oceanic crust until its possible transformation to AlSiO_3 H.
基金the CARLSBERG FOUNDATION for support to carry out this work via grant CF16-0059
文摘Corundum(ruby-sapphire) is known to have formed in situ within Archean metamorphic rocks at several localities in the North Atlantic Craton of Greenland. Here we present two case studies for such occurrences:(1) Maniitsoq region(Kangerdluarssuk), where kyanite paragneiss hosts ruby corundum, and(2)Nuuk region(Stor?), where sillimanite gneiss hosts ruby corundum. At both occurrences, ultramafic rocks(amphibole-peridotite) are in direct contact with the ruby-bearing zones, which have been transformed to mica schist by metasomatic reactions. The bulk-rock geochemistry of the ruby-bearing rocks is consistent with significant depletion of SiO_2 in combination with addition of Al_2O_3, MgO, K_2O,Th and Sr relative to an assumed aluminous precursor metapelite. Phase equilibria modelling supports ruby genesis from the breakdown of sillimanite and kyanite at elevated temperatures due to the removal of SiO_2. The juxtaposition of relatively silica-and aluminum-rich metasedimentary rocks with low silica ultramafic rocks established a chemical potential gradient that leached/mobilized SiO_2 allowing corundum to stabilize in the former rocks. Furthermore, addition of Al_2O_3 via a metasomatic reaction is required, because Al/Ti is fractionated between the aluminous precursor metapelites and the resulting corundum-bearing mica schist. We propose that Al was mobilized either by complexation with hydroxide at alkaline conditions, or that Al was transported as K-Al-Si-O polymers at deep crustal levels.The three main exploration vectors for corundum within Archean greenstone belts are:(1) amphiboliteto granulite-facies metamorphic conditions,(2) the juxtaposition of ultramafic rocks and aluminous metapelite, and(3) mica-rich reactions zones at their interface.
