Two-dimensional images of the granular ore media with different grain sizes were obtained from the X-ray computed tomography.Combined with the digital image processing and finite element techniques,the original graysc...Two-dimensional images of the granular ore media with different grain sizes were obtained from the X-ray computed tomography.Combined with the digital image processing and finite element techniques,the original grayscale images were transformed into the finite element models directly.By using these models,the simulations of pore scale fluid flow among particles were conducted with the COMSOL Multiphysics,and the distribution characteristics of fluid flow velocity and pressure were analyzed.The simulation results show that there exist obvious preferential flow and leaching blind zone in each granular medium.The flow velocity at pore throat is larger than that of pore body and the largest velocity reaches 0.22 m/s.The velocity decreases gradually from the center of pore throat and body to the surface of particles.The flow paths of granular media with larger grain size distribute equally,while the fluid flow velocities in most of areas of granular media with smaller grain size are lower,and some of them approach to zero,so the permeability is very low.There exist some pore clusters with different pressures,which is the basic reason for the uneven flow velocity distribution.展开更多
Governing equations for a fully coupled flowing-reaction-deformation behavior with mass transfer in heap leaching are developed. The model equations are solved using an explicit finite difference method under the cond...Governing equations for a fully coupled flowing-reaction-deformation behavior with mass transfer in heap leaching are developed. The model equations are solved using an explicit finite difference method under the conditions of invariable application rate and constant hydraulic head. The distribution of the degree of the saturation, as well as the distributions of the concentration of the reagent and the solute is given. A cubic relationship between the mineral recovery and the leaching duration is obtained based on the numerical results. The relationship can be used to predict the recovery percentage of the valuable metal.展开更多
Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic diffe...Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic difference method to give the distribution of the concentration of ferrous ion in the ore column. To calibrate the computational model, a column test was performed using infiltration of sulfide ferrous solution (the initial concentration is c0=0.04 mol/L) on a 100 cm high column composed of ore particles smaller than 10 mm for 2.5 h. The numerical analysis shows that the results obtained from numerical modeling under the same operating conditions as used for column test are in good agreement with those from experimental procedure on the whole trend, which indicates that the model, the numerical method, and the parameters chosen can reflect the rule of ferrous ion transmission in ore heap.展开更多
The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the nega...The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly ThiobaciUus ferrooxidan （named T.fl ）, as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5, and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day＇s bio-oxidization, among the samples sizing from 0 to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.展开更多
The column leaching experiment of ore granular media was carried out with the home-made multi-functional experimental apparatus and the pore structure of ore granular media was scanned by the X-ray computed tomography...The column leaching experiment of ore granular media was carried out with the home-made multi-functional experimental apparatus and the pore structure of ore granular media was scanned by the X-ray computed tomography machine before and after leaching.The porosities of each section before and after leaching were calculated based on CT images processing,and the permeability of each zone before and after leaching were also calculated with Carman-Kozeny equation.The permeability evolvement law was disclosed.The results indicate that before leaching the permeability of the ore granular media in different height has not much difference and the value ranges from 5.70×10-4mm 2to 1.11×10 -3mm 2,where the lowest one locates in the bottom zone.After leaching the permeability distributes inhomogeneously along the height of the column and the value ranges from 3.44×10 -4 mm 2 to 2.25×10 -2 mm 2 ,where the lowest one is in the same place.Except for the bottom zone,the permeability of other zones increases after leaching,especially the top zone.Through comparison of the permeability at bottom zone before and after leaching,the whole permeability after leaching decreases by 39.65%that coincides with the measured experimental data.展开更多
The capillary process coexists with gravity flow within leaching heap due to the dual-porosity structure. Capillary rise is responsible for the mineral dissolution in fine particle zones and interior coarse rock. The ...The capillary process coexists with gravity flow within leaching heap due to the dual-porosity structure. Capillary rise is responsible for the mineral dissolution in fine particle zones and interior coarse rock. The effect of particle size and heap porosity on the capillary process was investigated through a series of column tests. Macropore of the ore heap was identified, and its capillary rise theory analysis was put forward. Two groups of ore particles, mono-size and non-uniform, were selected for the capillary rise test. The result shows that particle size has an inverse effect on the capillary ultimate height, and smaller particles exhibit higher capillary rise. Meanwhile, the poorly graded group exhibits small rise height and velocity, while the capillary rise in the well-graded particles is much greater. The relationship between porosity and fitting parameters of capillary rise was obtained. Low porosity and high surface tension lead to higher capillary height of the fine gradation. Moisture content increases with the capillary rise level going up, the relationship between capillary height and moisture content was obtained.展开更多
A mathematical model for heap bioleaching is developed to analyze heat transfer, oxygen flow, target ion distribution and oxidation leaching rate in the heap. The model equations are solved with Comsol Multiphysics so...A mathematical model for heap bioleaching is developed to analyze heat transfer, oxygen flow, target ion distribution and oxidation leaching rate in the heap. The model equations are solved with Comsol Multiphysics software. Numerical simulation results show the following facts： Concentration of oxygen is relatively high along the boundary of the slope, and low in the center part where leaching rate is slow. Temper- ature is relatively low along the slope and reaches the highest along the bottom region near the slope, with difference being more than 6℃. Concentration of target mental ions is the highest in the bottom region near the slope. Oxidation leaching rate is relatively large in the bottom and slope part with a fast reaction rate, and small in the other part with low oxygen concentration.展开更多
Compared with the traditional pyrometallurgical process, copper bioleaching has distinctive advantages of high efficiency and lower cost, enabling efficiently extracts of valuable metal resources from copper sulfides....Compared with the traditional pyrometallurgical process, copper bioleaching has distinctive advantages of high efficiency and lower cost, enabling efficiently extracts of valuable metal resources from copper sulfides. Moreover, during long-term industrial applications of bioleaching, many regulatory enhancements and technological methods are used to accelerate the interfacial reactions. With advances in microbial genetic and sequencing technologies, bacterial communities and their mechanisms in bioleaching systems have been revealed gradually. The bacterial proliferation and dissolution of sulfide ores by a bacterial community depends on the pH, temperature, oxygen, reaction product regulation, additives, and passivation substances, among other factors. The internal relationship among the influencing factors and the succession of microorganism diversity are discussed and reviewed in this paper. This paper is intended to provide a good reference for studies related to enhanced bioleaching.展开更多
Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the...Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.展开更多
The images of granular ore media were captured by X-ray CT scanner. Combined with digital image processing and finite element techniques, the three-dimensional geometrical model, which represents the realistic pore st...The images of granular ore media were captured by X-ray CT scanner. Combined with digital image processing and finite element techniques, the three-dimensional geometrical model, which represents the realistic pore structure of the media, was constructed. With this model, three dimensional pore scale fluid flow among particles was simulated. Then the distributions of fluid flow velocity and pressure were analyzed and the hydraulic conductivity was calculated. The simulation results indicate the fluid flow behaviors are mainly dominated by the volume and topological structure of pore space. There exist obvious preferential flow and leaching blind zones simultaneously in the medium. The highest velocities generally occur in those narrow pores with high pressure drops. The hydraulic conductivity obtained by simulation is the same order of magnitude as the laboratory test result, which denotes the validity of the model. The pore-scale and macro-scale are combined and the established geometrical model can be used for the simulations of other phenomena during heap leaching process.展开更多
基金Projects(50934002,51074013) supported by the National Natural Science Foundation of China
文摘Two-dimensional images of the granular ore media with different grain sizes were obtained from the X-ray computed tomography.Combined with the digital image processing and finite element techniques,the original grayscale images were transformed into the finite element models directly.By using these models,the simulations of pore scale fluid flow among particles were conducted with the COMSOL Multiphysics,and the distribution characteristics of fluid flow velocity and pressure were analyzed.The simulation results show that there exist obvious preferential flow and leaching blind zone in each granular medium.The flow velocity at pore throat is larger than that of pore body and the largest velocity reaches 0.22 m/s.The velocity decreases gradually from the center of pore throat and body to the surface of particles.The flow paths of granular media with larger grain size distribute equally,while the fluid flow velocities in most of areas of granular media with smaller grain size are lower,and some of them approach to zero,so the permeability is very low.There exist some pore clusters with different pressures,which is the basic reason for the uneven flow velocity distribution.
基金Project supported by the National Basic Research and Development Program of China (No.2004CB619206)the National Science Fund for Distinguished Young Scholars (No.50325415)+1 种基金the National Science Fund for Innovative Research Group (No.50321402)the Natural Science Foundation of Hunan Province (No.06JJ30024)
文摘Governing equations for a fully coupled flowing-reaction-deformation behavior with mass transfer in heap leaching are developed. The model equations are solved using an explicit finite difference method under the conditions of invariable application rate and constant hydraulic head. The distribution of the degree of the saturation, as well as the distributions of the concentration of the reagent and the solute is given. A cubic relationship between the mineral recovery and the leaching duration is obtained based on the numerical results. The relationship can be used to predict the recovery percentage of the valuable metal.
基金Project(06JJ30024) supported by the Natural Science Foundation of Hunan Province, ChinaProject(2004CB619206) supported by the Major State Basic Research and Development Program of China+1 种基金Project(50321402) supported by the National Science Fund for Innovative Research Groups of ChinaProject(06B052) supported by the Scientific Research Fund of Hunan Provincial Education Department of China
文摘Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic difference method to give the distribution of the concentration of ferrous ion in the ore column. To calibrate the computational model, a column test was performed using infiltration of sulfide ferrous solution (the initial concentration is c0=0.04 mol/L) on a 100 cm high column composed of ore particles smaller than 10 mm for 2.5 h. The numerical analysis shows that the results obtained from numerical modeling under the same operating conditions as used for column test are in good agreement with those from experimental procedure on the whole trend, which indicates that the model, the numerical method, and the parameters chosen can reflect the rule of ferrous ion transmission in ore heap.
文摘The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly ThiobaciUus ferrooxidan （named T.fl ）, as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5, and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day＇s bio-oxidization, among the samples sizing from 0 to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.
基金Project(2004CB619205)supported by the National Basic Research Program of ChinaProject(50325415)supported by the National ScienceFund for Distinguished Young Scholars+1 种基金Project(50574099)supported by the National Natural Science Foundation of ChinaProject(06B052)supported by Scientific Research Foundation of Hunan Provincial Education Department,China
文摘The column leaching experiment of ore granular media was carried out with the home-made multi-functional experimental apparatus and the pore structure of ore granular media was scanned by the X-ray computed tomography machine before and after leaching.The porosities of each section before and after leaching were calculated based on CT images processing,and the permeability of each zone before and after leaching were also calculated with Carman-Kozeny equation.The permeability evolvement law was disclosed.The results indicate that before leaching the permeability of the ore granular media in different height has not much difference and the value ranges from 5.70×10-4mm 2to 1.11×10 -3mm 2,where the lowest one locates in the bottom zone.After leaching the permeability distributes inhomogeneously along the height of the column and the value ranges from 3.44×10 -4 mm 2 to 2.25×10 -2 mm 2 ,where the lowest one is in the same place.Except for the bottom zone,the permeability of other zones increases after leaching,especially the top zone.Through comparison of the permeability at bottom zone before and after leaching,the whole permeability after leaching decreases by 39.65%that coincides with the measured experimental data.
基金Project(51374035)supported by the National Natural Science Foundation of ChinaProject(201351)supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProject(NCET-13-0669)supported by Program for New Century Excellent Talents in University,China
文摘The capillary process coexists with gravity flow within leaching heap due to the dual-porosity structure. Capillary rise is responsible for the mineral dissolution in fine particle zones and interior coarse rock. The effect of particle size and heap porosity on the capillary process was investigated through a series of column tests. Macropore of the ore heap was identified, and its capillary rise theory analysis was put forward. Two groups of ore particles, mono-size and non-uniform, were selected for the capillary rise test. The result shows that particle size has an inverse effect on the capillary ultimate height, and smaller particles exhibit higher capillary rise. Meanwhile, the poorly graded group exhibits small rise height and velocity, while the capillary rise in the well-graded particles is much greater. The relationship between porosity and fitting parameters of capillary rise was obtained. Low porosity and high surface tension lead to higher capillary height of the fine gradation. Moisture content increases with the capillary rise level going up, the relationship between capillary height and moisture content was obtained.
基金Project supported by the National Natural Science Foundation of China (Nos. 50934002 and 50774011)the Postdoctoral Science Foundation of China (No. 20090450014)the DoctoralNatural Science Foundation of China (No. 20070008038)
文摘A mathematical model for heap bioleaching is developed to analyze heat transfer, oxygen flow, target ion distribution and oxidation leaching rate in the heap. The model equations are solved with Comsol Multiphysics software. Numerical simulation results show the following facts： Concentration of oxygen is relatively high along the boundary of the slope, and low in the center part where leaching rate is slow. Temper- ature is relatively low along the slope and reaches the highest along the bottom region near the slope, with difference being more than 6℃. Concentration of target mental ions is the highest in the bottom region near the slope. Oxidation leaching rate is relatively large in the bottom and slope part with a fast reaction rate, and small in the other part with low oxygen concentration.
基金financially supported by the National Key Research and Development Program of China (No. 2016YFC0600704)the National Science Fund for Excellent Young Scholars of China (No. 51722401)the Key Program of National Natural Science Foundation of China (No. 51734001)
文摘Compared with the traditional pyrometallurgical process, copper bioleaching has distinctive advantages of high efficiency and lower cost, enabling efficiently extracts of valuable metal resources from copper sulfides. Moreover, during long-term industrial applications of bioleaching, many regulatory enhancements and technological methods are used to accelerate the interfacial reactions. With advances in microbial genetic and sequencing technologies, bacterial communities and their mechanisms in bioleaching systems have been revealed gradually. The bacterial proliferation and dissolution of sulfide ores by a bacterial community depends on the pH, temperature, oxygen, reaction product regulation, additives, and passivation substances, among other factors. The internal relationship among the influencing factors and the succession of microorganism diversity are discussed and reviewed in this paper. This paper is intended to provide a good reference for studies related to enhanced bioleaching.
文摘Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.
基金Projects (50934002, 51074013, 51104100) supported by the National Natural Science Foundation of China
文摘The images of granular ore media were captured by X-ray CT scanner. Combined with digital image processing and finite element techniques, the three-dimensional geometrical model, which represents the realistic pore structure of the media, was constructed. With this model, three dimensional pore scale fluid flow among particles was simulated. Then the distributions of fluid flow velocity and pressure were analyzed and the hydraulic conductivity was calculated. The simulation results indicate the fluid flow behaviors are mainly dominated by the volume and topological structure of pore space. There exist obvious preferential flow and leaching blind zones simultaneously in the medium. The highest velocities generally occur in those narrow pores with high pressure drops. The hydraulic conductivity obtained by simulation is the same order of magnitude as the laboratory test result, which denotes the validity of the model. The pore-scale and macro-scale are combined and the established geometrical model can be used for the simulations of other phenomena during heap leaching process.
