Examining carbonate dissolution kinetics at mineral-water interface is crucial to understand numerous environmental and geochemical processes,including global carbon cycling,CO_(2)sequestration in deep geological rese...Examining carbonate dissolution kinetics at mineral-water interface is crucial to understand numerous environmental and geochemical processes,including global carbon cycling,CO_(2)sequestration in deep geological reservoirs,and trace elements release in terrestrial and aquatic environments.Here we explored the effect of circumneutral to alkaline pH solutions(pH 6-11)on dissolution kinetics of pure dolomite and Ca and Mg release stoichiometry in flow-through reactor experiments at 25±1℃.Results revealed that the dolomite dissolution rates obtained from effluent Ca and Mg concentrations(R_(Ca)and R_(Mg)in mol/cm^(2)/s)were dependent on input solution pH and HCO_(3)^(-)log activity.The pH dependence of dissolution rates showed two distinct trends,i.e.,at circumneutral pH ranging between 6 and 8,the dissolution rate decreased with increasing pH,with minimum rate at pH 8.While in the highly alkaline pH range(pH 9-11),the dolomite dissolution rate increased with an increasing pH.Irrespective of the input pH,the dolomite dissolution rates indicated a reverse relationship with HCO_(3)^(-)log activity,with the lowest dissolution rate(R Ca=3.80×10^(-12)mol/cm^(2)/s)at pH 8 where HCO_(3)^(-)log activity attained the highest value(-3.957).The lower R Ca and R Mg obtained at pH 8 compared to all the other pH could possibly be attributed to an inhibition caused by high HCO_(3)^(-)log activity in solution at this pH.Dolomite dissolution rates were non-stoichiometric at all the experimental pH values,showing higher preferential Ca over Mg release(R_(Ca)>R_(Mg))whereas an opposite trend was observed at pH 8,with R_(Ca)<R_(Mg)at the steady state.Saturation index values calculated using geochemical speciation modelling were positive for Mg-bearing minerals(brucite,dolomite,artinite)at alkaline pH of 10-11,indicating favourable conditions for their precipitation under studied conditions.This study provides insights on the significance of log ion activities of HCO_(3)^(-)and Me-OH^(+)under varying pH for elucidating the dissolution mechanism of dolomite in circumneutral to alkaline aqueous environments.展开更多
Cavitation,a phenomenon produced by a moving fluid,is ubiquitous in the water environment of the Earth's surface and its related mechanical action in the process of cavitation leads to the widespread erosion of ro...Cavitation,a phenomenon produced by a moving fluid,is ubiquitous in the water environment of the Earth's surface and its related mechanical action in the process of cavitation leads to the widespread erosion of rock in nature.Although the mechanical action of flowing water body that accelerates the rock mass loss and fragmentation of rock(abrasion,erosion,and etching)and other phenomena have been much studied,its acceleration of mineral crystal dissolution is rarely reported.The physical mechanism of effect is not yet clear.The cavitation bubble produced in the cavitation process is at the micron level,and its related mechanical action leading to the accumulation of rock mineral dissolution is manifested in time and space in the process of the chemical element's migration between water and rock minerals.Cavitation erosion may be one of the important driving forces for the migration of geochemical elements within the lithosphere and hydrosphere.In this paper,based on the crystal dissolution stepwave dynamic theory and the theoretical derivation and calculation of Gibbs free energy change of the mineral crystals plastic deformation which caused by the mechanical action of cavitation erosion,we give the possible mechanism of accelerating the transient dissolution of mineral crystals by cavitation erosion—the cavitation bubbles on the surface of the near crystal release the high speed micro-jet and shock wave perpendicular to the surface during the collapsing,in which the water hammer pressure produced by micro-jet at the solid–liquid interface causes instantaneous plastic deformation on the crystal surface under the condition that it is larger than the yield stress of the crystal.Under the influence of the thermal effect of the plastic deformation process and the change of Gibbs free energy(the dislocation elastic strain energy of plastic deformation on the crystal surface may be included),the local instantaneous dissolution rate of the mineral surface is accelerated.The continuous cavitation erosion eventually causes fracture and breaking of the mineral crystal,meanwhile,the Gibbs–Thomson effect may enhance the dissolution of mineral crystals more prominently.At the same time,the correctness of the mechanism is verified qualitatively by the acoustic cavitation experiment with the same erosion mechanism.展开更多
Ocean alkalinity enhancement(OAE)via carbonate dissolution has emerged as a promising approach for marine carbon dioxide removal(mCDR).However,the properties of oversaturated seawater in the upper ocean with respect t...Ocean alkalinity enhancement(OAE)via carbonate dissolution has emerged as a promising approach for marine carbon dioxide removal(mCDR).However,the properties of oversaturated seawater in the upper ocean with respect to calcium carbonate(CaCO_(3))minerals are unfavorable for their dissolution,and mediation strategies are thus required to improve the efficiency of OAE-mCDR.In this study,we conducted laboratory incubation experiments using nearshore surface seawater to examine the dissolution dynamics of natural(Iceland spar)and biogenic(Emiliania huxleyi coccolith)calcite minerals.In the experimental group with added bacteria,total alkalinity(TA)and dissolved inorganic carbon(DIC)concentrations markedly increased over the incubation period,corresponding to a notable decline in pH and dissolved organic carbon concentrations.Moreover,the concentration of dissolved calcium ions increased in the coccolith dissolution experiment.However,in the control group without bacteria,all the parameters were nearly constant or changed only slightly over time in both the Iceland spar and coccolith dissolution experiments.Therefore,microbial mediation clearly enhanced calcite mineral dissolution in oversaturated seawater,which likely occurred in the acidic microenvironments produced by bacterial metabolic activity.Linear regression analyses of the DIC and TA revealed that the relative contribution of CaCO_(3)dissolution to organic matter decomposition was 0.18±0.13 and 0.22±0.01,respectively,in the Iceland spar and coccolith experimental groups.The linear regression slope,defined as the OAE-mCDR efficiency indicating the amount of atmospheric CO_(2)absorbed per unit increase in TA,was 3.53±1.87 and 4.36±0.05 for the two groups.Both values exceed a theoretical value of 0.81 under the incubation seawater conditions,primarily driven by DIC increases from organic matter decomposition in the substrate medium.However,microbe-mineral interactions might also improve OAE performance and capabilities.We propose that microbial mediation plays an important role in promoting carbonate mineral dissolution,even in calcite-oversaturated seawater,and can be incorporated into future mCDR implementation strategies.展开更多
In the pursuit of sustainable oil and gas resource extraction,the innovative integration of carbon capture,utilization,and storage(CCUS)technology has emerged as the most promising approach.During the CCUS process,int...In the pursuit of sustainable oil and gas resource extraction,the innovative integration of carbon capture,utilization,and storage(CCUS)technology has emerged as the most promising approach.During the CCUS process,intricate physicochemical interactions between the injected CO_(2),facilitated through various injection strategies(Water Alternative Gas:WAG/Continue Gas Injection:CGI)and the formation fluids and heterogeneous mineral assemblages within the reservoir trigger alterations in mineral structures,consequently impacting permeability and recovery factors,constituting a pivotal aspect.Precisely delineating and quantifying these interactions is paramount for optimizing process design and evaluating reservoir dynamics in the successful implementation of CCUS operations.This study has carried out qualitative and quantitative characterization of mineral heterogeneity,different pore types,and mineral combination characteristics from a low-permeability sandstone reservoir.Additionally,the effect on the physical properties of minerals from different development methods(WAG/CGI)was investigated using numerical simulation for CCUS applications.The results indicate that the saturated CO_(2)fluid selectively dissolves the potassium feldspar(orthoclase)in intergranular pores,while the intergranular pores are filled with illite and secondary precipitated clay minerals.It initially dissolves the sensitive mineral(ankerite)in the intergranular pores.The decrease of ankerite and increase of illite result from the prolonged contact period between saturated CO_(2)and minerals,which changes the mineral cementation to argillaceous type,thus affecting permeability in the context of CCUS.The spatial impact on reservoir physical properties depends on the spatial heterogeneity of the original sensitive minerals(ankerite,anorthite,illite,etc.)distributed in the study area.In the WAG scheme,the physicochemical interaction between saturated CO_(2)and reservoir minerals is more intense than in the CGI scheme for CCUS operations,significantly impacting cumulative production.展开更多
The reactive surface area, an important parameter controlling mineral reactions, affects the amount of mineralization trapping of CO2 which affects the long-term CO2 storage. The effect of the reactive surface area on...The reactive surface area, an important parameter controlling mineral reactions, affects the amount of mineralization trapping of CO2 which affects the long-term CO2 storage. The effect of the reactive surface area on the mineralization trapping of CO2 was numerically simulated for CO2 storage in saline aquifers. Three kinds of minerals, including anorthite, calcite and kaolinite, are involved in the mineral reactions. This paper models the relationship between the specific surface area and the grain diameter of anorthite based on experimental data from literature （Brantley and Mellott, 2000）. When the reactive surface areas of anorthite and calcite decrease from 838 to 83.8 m^2/m^3, the percentage of mineralization trapping of CO： after 500 years decreases from 11.8% to 0.65%. The amount of dissolved anorthite and the amounts of precipitated kaolinite and calcite decrease significantly when the reactive surface areas ofanorthite and calcite decrease from 838 to 83.8 m2/m3. Calcite is initially dissolved in the brine and then precipitates during the geochemical reactions between CO2-H20 and the minerals. Different reactive surface areas of anorthite and calcite lead to different times from dissolution to precipitation. The pH of the brine decreases with decreasing reactive surface areas of anorthite and calcite which influences the acidity of the saline aquifer. The gas saturation between the upper and lower parts of the saline aquifer increases with decreasing reactive surface areas of anorthite and calcite. The mass density distribution of brine solution shows that the CO2^＋brine solution region increases with decreasing reactive surface areas ofanorthite and calcite.展开更多
Reverse flotation technology is one of the most efficient ways to improve the quality and reduce impurity of iron concentrate. Mineral processors dealing with hematite face a challenge that the flotation results of re...Reverse flotation technology is one of the most efficient ways to improve the quality and reduce impurity of iron concentrate. Mineral processors dealing with hematite face a challenge that the flotation results of reverse flotation of hematite are poor in presence of siderite using fatty acid as collector, starch as depressant of iron minerals and calcium ion as activator of quartz at strong alkaline pH. In this work, the effect of siderite on reverse anionic flotation of quartz from hematite was investigated. The effect mechanism of siderite on reverse flotation of hematite was studied by solution chemistry, ultraviolet spectrophotometry(UV) and Fourier transform infrared spectroscopy(FTIR). It was observed that siderite had strong depressive effect on quartz in flotation using sodium oleate as collector, corn starch as depressant of iron minerals and calcium chloride as activator of quartz at strong alkaline pH. The starch was adsorbed onto calcium carbonate by chemical reaction which was formed by CO^(2-)_3 from siderite dissolution and Ca^(2+) from calcium chloride as activator of quartz and precipitated on the surface of quartz, which resulted in improving the hydrophilic ability of quartz.展开更多
The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigat...The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigated by means of solution chemistry, ultraviolet spectrophotometry(UV), inductively coupled plasma atomic emission spectrometry(ICP-AES) and X-ray photoelectron spectroscopy(XPS). It is observed that dolomite with different size fractions has depressing effect on hematite flotation using sodium oleate as collector, and dolomite could be the "mineral depressant" of hematite using sodium oleate as collector. The reasons for that are concerned with sodium oleate consumption and the adsorption onto hematite of dissolved species of dolomite.展开更多
With increasing CO_(2)concentration in the atmosphere,CO_(2)geo-aequestration has become a popular technique to counter the dangers of global warming resulting from high levels of CO_(2)in the atmosphere.This paper ex...With increasing CO_(2)concentration in the atmosphere,CO_(2)geo-aequestration has become a popular technique to counter the dangers of global warming resulting from high levels of CO_(2)in the atmosphere.This paper examins sequestration parameters such as CO_(2)plume behaviour,residual gas trapping and injectivity as a means of achieving safe and successful CO_(2)storage in saline aquifers.Mineral precipitation/dissolution rates are used to establish a relationship between these parameters and geochemical reactions in saline aquifers.To achieve this,mechanistic models(6 models with different inputs,created using CMG e GEM,2016 and WINPROP,2016)are simulated using input data from literature and studying changes in fluids and formation properties as well as mineral precipitation/dissolution rates in aquifers when subjected to different conditions in the different models.The results from the models show that high CO_(2)dissolution,which creates large CO_(2)plume,leads to high mineral dissolution/precipitation as results of increased fluid-rock interactions(geochemical reactions);whereas injectivity,although enhanced by CO_(2)-water cyclic injection,does not show much increase in bottom hole pressure when mineral trapping(thus geochemical reactions)is introduced into the model.Sensitivity study on residual gas trapping shows that high residual gas saturation leads to reduced mineral precipitation/dissolution due to the reduced amount of dissolved CO_(2)in brine.Also,rapid changes in the bottom hole pressure at high residual gas saturation means that a formation that fosters high residual gas trapping,rather than CO_(2)dissolution in brine,is more likely to experience injectivity issues during the sequestration process.展开更多
The paper addresses the issues of reducing the concentration of greenhouse gases in the atmosphere through carbon dioxide sequestration by injection to geological formations to enhance oil recovery and underground sto...The paper addresses the issues of reducing the concentration of greenhouse gases in the atmosphere through carbon dioxide sequestration by injection to geological formations to enhance oil recovery and underground storage.Geochemical reactions occurring in a reservoir during CO_(2) injection can affect physical properties of the formation and mechanisms of carbon dioxide capture.The interactions in the“CO_(2)-formation water-rock”system are complex and depends on many factors:mineralogical composition of rock,composition and salinity of formation water,reservoir thermobaric conditions,time.The paper includes a brief review of carbon dioxide interaction studies with formation fluids and reservoir rock minerals.A methodology is presented for studying geochemical processes during interaction of carbon dioxide-saturated formation water with reservoir rock samples.Experimental results for oil-saturated and water-saturated,carbonate and terrigenous reservoir intervals are discussed.The experiments demonstrate complex interactions of CO_(2) with water and rocks under natural conditions.Important aspects are the influence of mineralogical composition on dissolution and secondary precipitation processes as well as changes in aqueous phase composition and pH.Hydrogeochemical modeling workflow for the studied processes is proposed with calibration to experimental data and their appropriate translation to reservoir conditions.The results demonstrate the need for detailed geochemical studies to better assess the effects of CO_(2) on reservoir properties and the risks associated with mineral deposition and dissolution during carbon capture and storage(CCS/CCUS)operations.展开更多
基金funding enabled and organized by CAUL and its Member Institutionsby COMSTEQ-TWAS research grant 2018(18-268 RG/EAS/AS_C)。
文摘Examining carbonate dissolution kinetics at mineral-water interface is crucial to understand numerous environmental and geochemical processes,including global carbon cycling,CO_(2)sequestration in deep geological reservoirs,and trace elements release in terrestrial and aquatic environments.Here we explored the effect of circumneutral to alkaline pH solutions(pH 6-11)on dissolution kinetics of pure dolomite and Ca and Mg release stoichiometry in flow-through reactor experiments at 25±1℃.Results revealed that the dolomite dissolution rates obtained from effluent Ca and Mg concentrations(R_(Ca)and R_(Mg)in mol/cm^(2)/s)were dependent on input solution pH and HCO_(3)^(-)log activity.The pH dependence of dissolution rates showed two distinct trends,i.e.,at circumneutral pH ranging between 6 and 8,the dissolution rate decreased with increasing pH,with minimum rate at pH 8.While in the highly alkaline pH range(pH 9-11),the dolomite dissolution rate increased with an increasing pH.Irrespective of the input pH,the dolomite dissolution rates indicated a reverse relationship with HCO_(3)^(-)log activity,with the lowest dissolution rate(R Ca=3.80×10^(-12)mol/cm^(2)/s)at pH 8 where HCO_(3)^(-)log activity attained the highest value(-3.957).The lower R Ca and R Mg obtained at pH 8 compared to all the other pH could possibly be attributed to an inhibition caused by high HCO_(3)^(-)log activity in solution at this pH.Dolomite dissolution rates were non-stoichiometric at all the experimental pH values,showing higher preferential Ca over Mg release(R_(Ca)>R_(Mg))whereas an opposite trend was observed at pH 8,with R_(Ca)<R_(Mg)at the steady state.Saturation index values calculated using geochemical speciation modelling were positive for Mg-bearing minerals(brucite,dolomite,artinite)at alkaline pH of 10-11,indicating favourable conditions for their precipitation under studied conditions.This study provides insights on the significance of log ion activities of HCO_(3)^(-)and Me-OH^(+)under varying pH for elucidating the dissolution mechanism of dolomite in circumneutral to alkaline aqueous environments.
基金financially supported by Key Research of Frontier Science, CAS, Grant. NO. QYZDY-SSWDQC010
文摘Cavitation,a phenomenon produced by a moving fluid,is ubiquitous in the water environment of the Earth's surface and its related mechanical action in the process of cavitation leads to the widespread erosion of rock in nature.Although the mechanical action of flowing water body that accelerates the rock mass loss and fragmentation of rock(abrasion,erosion,and etching)and other phenomena have been much studied,its acceleration of mineral crystal dissolution is rarely reported.The physical mechanism of effect is not yet clear.The cavitation bubble produced in the cavitation process is at the micron level,and its related mechanical action leading to the accumulation of rock mineral dissolution is manifested in time and space in the process of the chemical element's migration between water and rock minerals.Cavitation erosion may be one of the important driving forces for the migration of geochemical elements within the lithosphere and hydrosphere.In this paper,based on the crystal dissolution stepwave dynamic theory and the theoretical derivation and calculation of Gibbs free energy change of the mineral crystals plastic deformation which caused by the mechanical action of cavitation erosion,we give the possible mechanism of accelerating the transient dissolution of mineral crystals by cavitation erosion—the cavitation bubbles on the surface of the near crystal release the high speed micro-jet and shock wave perpendicular to the surface during the collapsing,in which the water hammer pressure produced by micro-jet at the solid–liquid interface causes instantaneous plastic deformation on the crystal surface under the condition that it is larger than the yield stress of the crystal.Under the influence of the thermal effect of the plastic deformation process and the change of Gibbs free energy(the dislocation elastic strain energy of plastic deformation on the crystal surface may be included),the local instantaneous dissolution rate of the mineral surface is accelerated.The continuous cavitation erosion eventually causes fracture and breaking of the mineral crystal,meanwhile,the Gibbs–Thomson effect may enhance the dissolution of mineral crystals more prominently.At the same time,the correctness of the mechanism is verified qualitatively by the acoustic cavitation experiment with the same erosion mechanism.
基金The National Natural Science Foundation of China under contract No.42421004.
文摘Ocean alkalinity enhancement(OAE)via carbonate dissolution has emerged as a promising approach for marine carbon dioxide removal(mCDR).However,the properties of oversaturated seawater in the upper ocean with respect to calcium carbonate(CaCO_(3))minerals are unfavorable for their dissolution,and mediation strategies are thus required to improve the efficiency of OAE-mCDR.In this study,we conducted laboratory incubation experiments using nearshore surface seawater to examine the dissolution dynamics of natural(Iceland spar)and biogenic(Emiliania huxleyi coccolith)calcite minerals.In the experimental group with added bacteria,total alkalinity(TA)and dissolved inorganic carbon(DIC)concentrations markedly increased over the incubation period,corresponding to a notable decline in pH and dissolved organic carbon concentrations.Moreover,the concentration of dissolved calcium ions increased in the coccolith dissolution experiment.However,in the control group without bacteria,all the parameters were nearly constant or changed only slightly over time in both the Iceland spar and coccolith dissolution experiments.Therefore,microbial mediation clearly enhanced calcite mineral dissolution in oversaturated seawater,which likely occurred in the acidic microenvironments produced by bacterial metabolic activity.Linear regression analyses of the DIC and TA revealed that the relative contribution of CaCO_(3)dissolution to organic matter decomposition was 0.18±0.13 and 0.22±0.01,respectively,in the Iceland spar and coccolith experimental groups.The linear regression slope,defined as the OAE-mCDR efficiency indicating the amount of atmospheric CO_(2)absorbed per unit increase in TA,was 3.53±1.87 and 4.36±0.05 for the two groups.Both values exceed a theoretical value of 0.81 under the incubation seawater conditions,primarily driven by DIC increases from organic matter decomposition in the substrate medium.However,microbe-mineral interactions might also improve OAE performance and capabilities.We propose that microbial mediation plays an important role in promoting carbonate mineral dissolution,even in calcite-oversaturated seawater,and can be incorporated into future mCDR implementation strategies.
基金support of The National Foreign Experts Program(Grant no.QN2022060001L)Ministry of Science and Technology of China and Intelligent Reservoir Numerical Simulation Technology(Grant no.2023DJ8403),China National Petroleum Corporation.
文摘In the pursuit of sustainable oil and gas resource extraction,the innovative integration of carbon capture,utilization,and storage(CCUS)technology has emerged as the most promising approach.During the CCUS process,intricate physicochemical interactions between the injected CO_(2),facilitated through various injection strategies(Water Alternative Gas:WAG/Continue Gas Injection:CGI)and the formation fluids and heterogeneous mineral assemblages within the reservoir trigger alterations in mineral structures,consequently impacting permeability and recovery factors,constituting a pivotal aspect.Precisely delineating and quantifying these interactions is paramount for optimizing process design and evaluating reservoir dynamics in the successful implementation of CCUS operations.This study has carried out qualitative and quantitative characterization of mineral heterogeneity,different pore types,and mineral combination characteristics from a low-permeability sandstone reservoir.Additionally,the effect on the physical properties of minerals from different development methods(WAG/CGI)was investigated using numerical simulation for CCUS applications.The results indicate that the saturated CO_(2)fluid selectively dissolves the potassium feldspar(orthoclase)in intergranular pores,while the intergranular pores are filled with illite and secondary precipitated clay minerals.It initially dissolves the sensitive mineral(ankerite)in the intergranular pores.The decrease of ankerite and increase of illite result from the prolonged contact period between saturated CO_(2)and minerals,which changes the mineral cementation to argillaceous type,thus affecting permeability in the context of CCUS.The spatial impact on reservoir physical properties depends on the spatial heterogeneity of the original sensitive minerals(ankerite,anorthite,illite,etc.)distributed in the study area.In the WAG scheme,the physicochemical interaction between saturated CO_(2)and reservoir minerals is more intense than in the CGI scheme for CCUS operations,significantly impacting cumulative production.
基金supported by the National Natural Science Foundation of China (Grant No. 50906043)the Tsinghua University Initiative Scientific Research Program(2009THZ02232)The first author did this study while at Geoscience Australia sponsored by CAGS (China-Australia Geological Storage of CO2Project)
文摘The reactive surface area, an important parameter controlling mineral reactions, affects the amount of mineralization trapping of CO2 which affects the long-term CO2 storage. The effect of the reactive surface area on the mineralization trapping of CO2 was numerically simulated for CO2 storage in saline aquifers. Three kinds of minerals, including anorthite, calcite and kaolinite, are involved in the mineral reactions. This paper models the relationship between the specific surface area and the grain diameter of anorthite based on experimental data from literature （Brantley and Mellott, 2000）. When the reactive surface areas of anorthite and calcite decrease from 838 to 83.8 m^2/m^3, the percentage of mineralization trapping of CO： after 500 years decreases from 11.8% to 0.65%. The amount of dissolved anorthite and the amounts of precipitated kaolinite and calcite decrease significantly when the reactive surface areas ofanorthite and calcite decrease from 838 to 83.8 m2/m3. Calcite is initially dissolved in the brine and then precipitates during the geochemical reactions between CO2-H20 and the minerals. Different reactive surface areas of anorthite and calcite lead to different times from dissolution to precipitation. The pH of the brine decreases with decreasing reactive surface areas of anorthite and calcite which influences the acidity of the saline aquifer. The gas saturation between the upper and lower parts of the saline aquifer increases with decreasing reactive surface areas of anorthite and calcite. The mass density distribution of brine solution shows that the CO2^＋brine solution region increases with decreasing reactive surface areas ofanorthite and calcite.
基金Project(51374079) supported by the National Natural Science Foundation of China
文摘Reverse flotation technology is one of the most efficient ways to improve the quality and reduce impurity of iron concentrate. Mineral processors dealing with hematite face a challenge that the flotation results of reverse flotation of hematite are poor in presence of siderite using fatty acid as collector, starch as depressant of iron minerals and calcium ion as activator of quartz at strong alkaline pH. In this work, the effect of siderite on reverse anionic flotation of quartz from hematite was investigated. The effect mechanism of siderite on reverse flotation of hematite was studied by solution chemistry, ultraviolet spectrophotometry(UV) and Fourier transform infrared spectroscopy(FTIR). It was observed that siderite had strong depressive effect on quartz in flotation using sodium oleate as collector, corn starch as depressant of iron minerals and calcium chloride as activator of quartz at strong alkaline pH. The starch was adsorbed onto calcium carbonate by chemical reaction which was formed by CO^(2-)_3 from siderite dissolution and Ca^(2+) from calcium chloride as activator of quartz and precipitated on the surface of quartz, which resulted in improving the hydrophilic ability of quartz.
基金Project(51374079)supported by the National Natural Science Foundation of ChinaProject(KKSY201521031)supported by Talent Cultivation Foundation of Kunming University of Science and Technology,ChinaProject(2015Y067)supported by Foundation of Yunnan Educational Committee,China
文摘The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigated by means of solution chemistry, ultraviolet spectrophotometry(UV), inductively coupled plasma atomic emission spectrometry(ICP-AES) and X-ray photoelectron spectroscopy(XPS). It is observed that dolomite with different size fractions has depressing effect on hematite flotation using sodium oleate as collector, and dolomite could be the "mineral depressant" of hematite using sodium oleate as collector. The reasons for that are concerned with sodium oleate consumption and the adsorption onto hematite of dissolved species of dolomite.
文摘With increasing CO_(2)concentration in the atmosphere,CO_(2)geo-aequestration has become a popular technique to counter the dangers of global warming resulting from high levels of CO_(2)in the atmosphere.This paper examins sequestration parameters such as CO_(2)plume behaviour,residual gas trapping and injectivity as a means of achieving safe and successful CO_(2)storage in saline aquifers.Mineral precipitation/dissolution rates are used to establish a relationship between these parameters and geochemical reactions in saline aquifers.To achieve this,mechanistic models(6 models with different inputs,created using CMG e GEM,2016 and WINPROP,2016)are simulated using input data from literature and studying changes in fluids and formation properties as well as mineral precipitation/dissolution rates in aquifers when subjected to different conditions in the different models.The results from the models show that high CO_(2)dissolution,which creates large CO_(2)plume,leads to high mineral dissolution/precipitation as results of increased fluid-rock interactions(geochemical reactions);whereas injectivity,although enhanced by CO_(2)-water cyclic injection,does not show much increase in bottom hole pressure when mineral trapping(thus geochemical reactions)is introduced into the model.Sensitivity study on residual gas trapping shows that high residual gas saturation leads to reduced mineral precipitation/dissolution due to the reduced amount of dissolved CO_(2)in brine.Also,rapid changes in the bottom hole pressure at high residual gas saturation means that a formation that fosters high residual gas trapping,rather than CO_(2)dissolution in brine,is more likely to experience injectivity issues during the sequestration process.
基金The results presented in the paper partially represent a contribution to the fulfillment of the state assignment of OGRI RAS(topic 125020501405-1).
文摘The paper addresses the issues of reducing the concentration of greenhouse gases in the atmosphere through carbon dioxide sequestration by injection to geological formations to enhance oil recovery and underground storage.Geochemical reactions occurring in a reservoir during CO_(2) injection can affect physical properties of the formation and mechanisms of carbon dioxide capture.The interactions in the“CO_(2)-formation water-rock”system are complex and depends on many factors:mineralogical composition of rock,composition and salinity of formation water,reservoir thermobaric conditions,time.The paper includes a brief review of carbon dioxide interaction studies with formation fluids and reservoir rock minerals.A methodology is presented for studying geochemical processes during interaction of carbon dioxide-saturated formation water with reservoir rock samples.Experimental results for oil-saturated and water-saturated,carbonate and terrigenous reservoir intervals are discussed.The experiments demonstrate complex interactions of CO_(2) with water and rocks under natural conditions.Important aspects are the influence of mineralogical composition on dissolution and secondary precipitation processes as well as changes in aqueous phase composition and pH.Hydrogeochemical modeling workflow for the studied processes is proposed with calibration to experimental data and their appropriate translation to reservoir conditions.The results demonstrate the need for detailed geochemical studies to better assess the effects of CO_(2) on reservoir properties and the risks associated with mineral deposition and dissolution during carbon capture and storage(CCS/CCUS)operations.
