The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching effic...The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69 μm, holding at 80 ℃ for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2-1, and the ratio (g/mL) of solid to liquid being 1-10.展开更多
The anodic reaction kinetics of zinc electrowinning was investigated on the titanium base RuO2 anode in the system of Zn（Ⅱ）-NH3-NH4Cl-H2O. The effects of stirring speed, ammonium chloride concentration and temperat...The anodic reaction kinetics of zinc electrowinning was investigated on the titanium base RuO2 anode in the system of Zn（Ⅱ）-NH3-NH4Cl-H2O. The effects of stirring speed, ammonium chloride concentration and temperature on anodic reaction rate were studied through the curve measurement of potentiostatic polarization. The results reveal that the electrochemically controlled anodic reaction obeys Tafel equation and the anodic reaction order for ammonium chloride is 1.056, with the apparent activation energy of 40.17 kJ/mol. The general equation of anodic reaction kinetics was obtained.展开更多
The crystal detachment behaviors from a chilling solid surface with vibration were investigated using a transparent NH4Cl-70%H2O alloy.The nucleation experiments of NH4Cl-70%H2O alloy were performed on a chilling surf...The crystal detachment behaviors from a chilling solid surface with vibration were investigated using a transparent NH4Cl-70%H2O alloy.The nucleation experiments of NH4Cl-70%H2O alloy were performed on a chilling surface generator with various vibration frequency from 20 to 1 000 Hz and vibration acceleration from 10 to 100 m/s2.The results indicate that the crystal detach rate increases and the grains are refined with increasing vibration acceleration under a certain vibration frequency.It is interesting to note that,when the frequency is 50 Hz,acceleration is 100 m/s2,the crystal detach rate increases sharply and the grain refinement effect is strengthened.A special grain refinement phenomenon can be observed,when the vibration acceleration and frequency are up to a critical value.A power-based definition was introduced in order to describe the relationship between the vibration parameters and imposed power on the system.It is found that a power criterion exists for the grain refinement in the current system.展开更多
Single-phaseα-CaSO4·0.5H2O whiskers were directly synthesized from waste Ca(NO3)2 solution using a hydrothermal method,and HNO3 was synchronously regenerated.The effects of reaction temperature and Ca^2+concentr...Single-phaseα-CaSO4·0.5H2O whiskers were directly synthesized from waste Ca(NO3)2 solution using a hydrothermal method,and HNO3 was synchronously regenerated.The effects of reaction temperature and Ca^2+concentration on the phase composition and morphology of products were determined by X-ray diffraction and optical microscopy.On the basis of the experimental results,the formation diagram ofα-CaSO4·0.5H2O was plotted within the range of 5–35 g·L^-1 Ca^2+and 115°C–150°C.In addition,the conditions of the direct synthesis ofα-CaSO4·0.5H2O were determined.Well-crystallized,single-phaseα-CaSO4·0.5H2O whiskers with high aspect ratios(length,1785μm;diameter,10.63μm;aspect ratio,168)and HNO3(70.25 g·L^-1)were obtained at the optimal conditions of 25 g·L^-1 Ca^2+and 125°C.展开更多
In this paper we have systematically studied V-L equilibrium in ternary aqueous solutions containingvolatile electrolytes by introducing a ternary interaction term into Edwards generalized molecular thermody-namic mod...In this paper we have systematically studied V-L equilibrium in ternary aqueous solutions containingvolatile electrolytes by introducing a ternary interaction term into Edwards generalized molecular thermody-namic model and optimizing several adjustable parameters.The program PARA9 with flexible functions ofdoing a series of calculations has been developed and carried out on a TQ-16 computer.It can be usedeither for directly calculating the V-L equilibrium or for optimizing the adjustable parameters.For the sys-toms（NH3-CO3-H2O3,NH3-H2S-H2O and NH3-SO2-H2O）satisfactory results have been obtained withrelative mean deviation of 5-10%.Besides,several sets of adjustable parameters and valuable information ofactivity coefficients,equilibrium concentrations of ions and molecules in solutions are obtained.展开更多
基金Project(2007CB613604) supported by the Major State Basic Research Development Program of ChinaProject(50674104) supported by the National Natural Science Foundation of ChinaProject(GJJ08279) supported by the Department of Education of Jiangxi Province
文摘The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69 μm, holding at 80 ℃ for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2-1, and the ratio (g/mL) of solid to liquid being 1-10.
文摘The anodic reaction kinetics of zinc electrowinning was investigated on the titanium base RuO2 anode in the system of Zn（Ⅱ）-NH3-NH4Cl-H2O. The effects of stirring speed, ammonium chloride concentration and temperature on anodic reaction rate were studied through the curve measurement of potentiostatic polarization. The results reveal that the electrochemically controlled anodic reaction obeys Tafel equation and the anodic reaction order for ammonium chloride is 1.056, with the apparent activation energy of 40.17 kJ/mol. The general equation of anodic reaction kinetics was obtained.
基金Projects(50571029,50771083) supported by the National Natural Science Foundation of ChinaProjects(02-TZ-2008,36-TP-2009) supported by State Key Laboratory of Solidification Processing in NWPU,China
文摘The crystal detachment behaviors from a chilling solid surface with vibration were investigated using a transparent NH4Cl-70%H2O alloy.The nucleation experiments of NH4Cl-70%H2O alloy were performed on a chilling surface generator with various vibration frequency from 20 to 1 000 Hz and vibration acceleration from 10 to 100 m/s2.The results indicate that the crystal detach rate increases and the grains are refined with increasing vibration acceleration under a certain vibration frequency.It is interesting to note that,when the frequency is 50 Hz,acceleration is 100 m/s2,the crystal detach rate increases sharply and the grain refinement effect is strengthened.A special grain refinement phenomenon can be observed,when the vibration acceleration and frequency are up to a critical value.A power-based definition was introduced in order to describe the relationship between the vibration parameters and imposed power on the system.It is found that a power criterion exists for the grain refinement in the current system.
基金supported by the Beijing Natural Science Foundation of China(2182040)the National Natural Science Foundation of China(51674026,U1802253)+1 种基金the Fundamental Research Funds for the Central Universities(FRF-TT-19-001)the China Scholarship Council(201906465004)。
文摘Single-phaseα-CaSO4·0.5H2O whiskers were directly synthesized from waste Ca(NO3)2 solution using a hydrothermal method,and HNO3 was synchronously regenerated.The effects of reaction temperature and Ca^2+concentration on the phase composition and morphology of products were determined by X-ray diffraction and optical microscopy.On the basis of the experimental results,the formation diagram ofα-CaSO4·0.5H2O was plotted within the range of 5–35 g·L^-1 Ca^2+and 115°C–150°C.In addition,the conditions of the direct synthesis ofα-CaSO4·0.5H2O were determined.Well-crystallized,single-phaseα-CaSO4·0.5H2O whiskers with high aspect ratios(length,1785μm;diameter,10.63μm;aspect ratio,168)and HNO3(70.25 g·L^-1)were obtained at the optimal conditions of 25 g·L^-1 Ca^2+and 125°C.
文摘In this paper we have systematically studied V-L equilibrium in ternary aqueous solutions containingvolatile electrolytes by introducing a ternary interaction term into Edwards generalized molecular thermody-namic model and optimizing several adjustable parameters.The program PARA9 with flexible functions ofdoing a series of calculations has been developed and carried out on a TQ-16 computer.It can be usedeither for directly calculating the V-L equilibrium or for optimizing the adjustable parameters.For the sys-toms（NH3-CO3-H2O3,NH3-H2S-H2O and NH3-SO2-H2O）satisfactory results have been obtained withrelative mean deviation of 5-10%.Besides,several sets of adjustable parameters and valuable information ofactivity coefficients,equilibrium concentrations of ions and molecules in solutions are obtained.
