The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficie...The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast （leaching efficiency is larger than 60%）. The second stage is the leaching of diffiuent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H2SO4 is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.展开更多
The leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate was studied.The effects including leaching temperature, reaction time, particle size, stirring speed, and concen...The leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate was studied.The effects including leaching temperature, reaction time, particle size, stirring speed, and concentrations of sulfuric acid and sodium peroxodisulfate were investigated. The leaching process of molybdenum from Ni-Mo ore is controlled by the chemical reaction through the solid layer across the unreacted shrinking core. The apparent activation energy of the leaching of molybdenum is calculated to be 41.0 k J/mol and the leaching kinetics equation of molybdenum from Ni-Mo ore is expressed as1-(1-a)1/3=3405.7exp[-41030.0/(RT)]t.展开更多
The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc ...The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc extractant, were clarified. The effects of agitation speed, specific interfacial area, temperature, extractant concentration and Zn ion concentration on the extraction rate are studied in constant interfacial area cell. The results show that the extraction rate depends on interfacial chemical reaction and diffusion by using this new extraetant to extract zinc, and the apparent activation energy of this extraction reaction is measured as 28.2 kJ/mol, which demonstrates that the extraction reaction is controlled by the mixed-controlled reaction rate. The apparent reaction orders a and b are measured as 1 and 0.38, and the constant k0 is 138.70. So, when extraction conditions are controlled as [HR]=20%-50%, T=0-30℃, N=120-177 r/min and S=72.6-127.5 m-1, the solvent extraction reaction rate can be depicted as v/（mol . m-2 . s-1 ） = 138.7. exp（ - 28 206/8.314T ）. [Zn 2＋ ]r ·[HR ]o0.38.展开更多
Isothermal experiments on the reduction of Fe_2O_3-Cr_2O_3-NiO(molar ratio of Fe-to-Cr-to-Ni is 3:2:2)by graphite were carried out at 1350–1550°C,and effects of various factors on reduction degree were studied.T...Isothermal experiments on the reduction of Fe_2O_3-Cr_2O_3-NiO(molar ratio of Fe-to-Cr-to-Ni is 3:2:2)by graphite were carried out at 1350–1550°C,and effects of various factors on reduction degree were studied.The results show that the reaction rate of the Fe_2O_3-Cr_2O_3-NiO system is fast during the initial period(reduction degree,α<38%),and then the rate decreases until the end of the reduction.Factors such as temperature,carbon content,sample size have a more significant effect during the final stage(α>38%).The metallic product formed at the initial stage(a Fe-Ni alloy)greatly promotes the reduction of Cr2O3 at the final stage.Further,during the reduction of Fe_2O_3-Cr_2O_3-NiO by carbon,interfacial reaction is the rate-controlling step and g(α)=1-(1-α)0.5 is the reaction mechanism for the initial stage,whereas two-dimensional diffusion is the rate-controlling step and f(α)=α+(1-α)ln(1-α)is the reaction mechanism for the final stage.The apparent activation energies are 55.43 k J/mol and 174.54 k J/mol for the initial and the final stages,respectively.展开更多
基金Project(2005BA639C) supported by the National Science and Technology Development of China
文摘The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast （leaching efficiency is larger than 60%）. The second stage is the leaching of diffiuent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H2SO4 is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.
基金Project(51364009) supported by the National Natural Science Foundation of ChinaProject(JSU071302) supported by the Construct Program of the Key Discipline in Hunan Province,ChinaProject(2015JJ2115) supported by the Natural Science Foundation of Hunan Province,China
文摘The leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate was studied.The effects including leaching temperature, reaction time, particle size, stirring speed, and concentrations of sulfuric acid and sodium peroxodisulfate were investigated. The leaching process of molybdenum from Ni-Mo ore is controlled by the chemical reaction through the solid layer across the unreacted shrinking core. The apparent activation energy of the leaching of molybdenum is calculated to be 41.0 k J/mol and the leaching kinetics equation of molybdenum from Ni-Mo ore is expressed as1-(1-a)1/3=3405.7exp[-41030.0/(RT)]t.
基金Foundation item： Project（51174240） supported by the National Natural Science Foundation of China Project（2006BA02B04-4-2） supported by the National Eleventh Five-Year Research Program of China Project（20100908） supported by Scientific and Industrial Research Organisation of Guangdong Province, China
文摘The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc extractant, were clarified. The effects of agitation speed, specific interfacial area, temperature, extractant concentration and Zn ion concentration on the extraction rate are studied in constant interfacial area cell. The results show that the extraction rate depends on interfacial chemical reaction and diffusion by using this new extraetant to extract zinc, and the apparent activation energy of this extraction reaction is measured as 28.2 kJ/mol, which demonstrates that the extraction reaction is controlled by the mixed-controlled reaction rate. The apparent reaction orders a and b are measured as 1 and 0.38, and the constant k0 is 138.70. So, when extraction conditions are controlled as [HR]=20%-50%, T=0-30℃, N=120-177 r/min and S=72.6-127.5 m-1, the solvent extraction reaction rate can be depicted as v/（mol . m-2 . s-1 ） = 138.7. exp（ - 28 206/8.314T ）. [Zn 2＋ ]r ·[HR ]o0.38.
基金Project(51074025) supported by the National Natural Science Foundation of ChinaProject(FRF-SD-12-009A) supported by the Fundamental Research Funds for the Central Universities,China
文摘Isothermal experiments on the reduction of Fe_2O_3-Cr_2O_3-NiO(molar ratio of Fe-to-Cr-to-Ni is 3:2:2)by graphite were carried out at 1350–1550°C,and effects of various factors on reduction degree were studied.The results show that the reaction rate of the Fe_2O_3-Cr_2O_3-NiO system is fast during the initial period(reduction degree,α<38%),and then the rate decreases until the end of the reduction.Factors such as temperature,carbon content,sample size have a more significant effect during the final stage(α>38%).The metallic product formed at the initial stage(a Fe-Ni alloy)greatly promotes the reduction of Cr2O3 at the final stage.Further,during the reduction of Fe_2O_3-Cr_2O_3-NiO by carbon,interfacial reaction is the rate-controlling step and g(α)=1-(1-α)0.5 is the reaction mechanism for the initial stage,whereas two-dimensional diffusion is the rate-controlling step and f(α)=α+(1-α)ln(1-α)is the reaction mechanism for the final stage.The apparent activation energies are 55.43 k J/mol and 174.54 k J/mol for the initial and the final stages,respectively.
