In order to simulate field distribution rules,mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established,based on theories of permeability and dynamic dispersion through poro...In order to simulate field distribution rules,mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established,based on theories of permeability and dynamic dispersion through porous media. A gas dispersion equation in a 3-D field is calculated by use of numerical method on a weighted upstream multi-element balance. Based on data of an example with a U type ventilation mode,surface charts of air pressure distribution and gas concentration are drawn by Graphtool software. Finally,a comparison between actually measured results in the model test and the numerical simulation results is made to proves the numerical implementation feasible.展开更多
The leaching kinetics in cyanide media of the silver contained in the Dos Carlos waste tailings at the City of Pachuca de Soto, Hidalgo State, Mexico were carried out. The used material contained the following chemica...The leaching kinetics in cyanide media of the silver contained in the Dos Carlos waste tailings at the City of Pachuca de Soto, Hidalgo State, Mexico were carried out. The used material contained the following chemical composition: 56 10-6of Ag, 0.6 10 6of Au and 70.43%(by weight) of SiO2; 7.032%(by weight) of Al2O3; 2.69%(by weight) of Fe; 0.46%(by weight) of Mn; 3.98%(by weight) of K2O; 3.34%(by weight) of CaO; 2.50%(by weight) of Na2O; 0.04%(by weight) of Zn; 0.026%(by weight) of Pb. The mineralogical phases present were the following: Silica, albite, argentite, berlinite, orthoclase, potassium jarosite, and natrojarosite. In the leaching kinetics in cyanide media, and under the studied conditions,the effect of the CN concentration on the reaction rate has no effect on the whole process of alkaline cyanidation, of which the reaction order is n 0. Temperature has an effect on the cyanidation rate of the reaction, with an activation energy of 47.9 KJ/mol. At the same time, when the particle size decreases there is an increase in the reaction rate, which is inversely proportional to the particle diameter; when increasing the NaOH concentration there is an increase in the reaction rate Kexp, with a reaction order(n) of 0.215 under the studied ranges.展开更多
The stress state and floating sinking reqularity of various particles in fly ash in water were analyzed. The formula for calculating the floating sinking rate was given. And the formula for calculating the magnetic fo...The stress state and floating sinking reqularity of various particles in fly ash in water were analyzed. The formula for calculating the floating sinking rate was given. And the formula for calculating the magnetic force needed to separate magnetic beads from magnetic separator was also obtained.展开更多
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
基金Projects 50534090 and 50674090 supported by the National Natural Science Foundation of China2005CB221503 by the National Key Basic ResearchDevelopment Program (973 Program)
文摘In order to simulate field distribution rules,mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established,based on theories of permeability and dynamic dispersion through porous media. A gas dispersion equation in a 3-D field is calculated by use of numerical method on a weighted upstream multi-element balance. Based on data of an example with a U type ventilation mode,surface charts of air pressure distribution and gas concentration are drawn by Graphtool software. Finally,a comparison between actually measured results in the model test and the numerical simulation results is made to proves the numerical implementation feasible.
基金the Autonomous University of Hidalgo State, Mexico for the financial support
文摘The leaching kinetics in cyanide media of the silver contained in the Dos Carlos waste tailings at the City of Pachuca de Soto, Hidalgo State, Mexico were carried out. The used material contained the following chemical composition: 56 10-6of Ag, 0.6 10 6of Au and 70.43%(by weight) of SiO2; 7.032%(by weight) of Al2O3; 2.69%(by weight) of Fe; 0.46%(by weight) of Mn; 3.98%(by weight) of K2O; 3.34%(by weight) of CaO; 2.50%(by weight) of Na2O; 0.04%(by weight) of Zn; 0.026%(by weight) of Pb. The mineralogical phases present were the following: Silica, albite, argentite, berlinite, orthoclase, potassium jarosite, and natrojarosite. In the leaching kinetics in cyanide media, and under the studied conditions,the effect of the CN concentration on the reaction rate has no effect on the whole process of alkaline cyanidation, of which the reaction order is n 0. Temperature has an effect on the cyanidation rate of the reaction, with an activation energy of 47.9 KJ/mol. At the same time, when the particle size decreases there is an increase in the reaction rate, which is inversely proportional to the particle diameter; when increasing the NaOH concentration there is an increase in the reaction rate Kexp, with a reaction order(n) of 0.215 under the studied ranges.
文摘The stress state and floating sinking reqularity of various particles in fly ash in water were analyzed. The formula for calculating the floating sinking rate was given. And the formula for calculating the magnetic force needed to separate magnetic beads from magnetic separator was also obtained.
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.
