This paper proposes a novel method relating to the recycling of waste lead ash originated from procedure of lead alloy production.The spent lead ash was first disposed by acetic acid leaching system,where lead ash str...This paper proposes a novel method relating to the recycling of waste lead ash originated from procedure of lead alloy production.The spent lead ash was first disposed by acetic acid leaching system,where lead ash structure wrapping impurities would be destroyed.The synthesis of lead oxide products was conducted at a lower temperature of 90℃.The effect of molar ratio of CH3 COOH to lead content of the ash on leaching efficiency was studied through the acetic acid leaching system.The results demonstrate that 84.6%of lead could be obtained in the leaching solution,while merely 0.7%of Fe blend in solution within a leaching time of 120 min.In the stage of lead oxide synthesis from leaching solution,the yield of lead oxide products could reach up to 94.4%when the molar ratio of NaOH to lead in filtrate was 2.5.This novel green method could shed light on the reuse of lead from exhausted ash with a much more convenient and environmentally friendly procedure.展开更多
Samaras or winged seeds spread themselves by wind. Ash seed, unlike other samaras, has a high aspect ratio wing which can generate enough lift force to slow down descent by rotating about the vertical axis and spinnin...Samaras or winged seeds spread themselves by wind. Ash seed, unlike other samaras, has a high aspect ratio wing which can generate enough lift force to slow down descent by rotating about the vertical axis and spinning around its wing span axis simultaneously. This unique kinematics and inherent fluid mechanism are definitely of great interest. Detailed kinematics of free falling ash seeds were measured using high-speed cameras, then corresponding aerodynamic forces and moments were calculated employing computational fluid dynamics. The results show that both rotating and spinning directions are in the same side and the spinning angular velocity is about 6 times of rotating speed. The terminal descending velocity and cone angles are similar to other samaras. Analysis of the forces and moments shows that the lift is enough to balance the weight and the vertical rotation results from a processional motion of total angular moment because the spin-cycle-averaged aer-odynamic moment is perpendicular to the total angular moment and can only change its direction but maintain its magnitude, which is very similar to a spinning top in processional motion except that the total angular moment of ash seed is not along the spin axis but almost normal to it. The flow structures show that both leading and trailing edge vortices contribute to lift generation and the spanwise spinning results in an augmentation of the lift, implying that ash seeds with high aspect ratio wing may evolve in a different way in utilizing fluid mechanisms to facilitate dispersal.展开更多
基金Supported by the China Postdoctoral Science Foundation(2018M632799)the Education Department of Henan Province Science Research Program(18B610008,19A610010)the Henan province Key Research and Development and Promotion(182102311033)
文摘This paper proposes a novel method relating to the recycling of waste lead ash originated from procedure of lead alloy production.The spent lead ash was first disposed by acetic acid leaching system,where lead ash structure wrapping impurities would be destroyed.The synthesis of lead oxide products was conducted at a lower temperature of 90℃.The effect of molar ratio of CH3 COOH to lead content of the ash on leaching efficiency was studied through the acetic acid leaching system.The results demonstrate that 84.6%of lead could be obtained in the leaching solution,while merely 0.7%of Fe blend in solution within a leaching time of 120 min.In the stage of lead oxide synthesis from leaching solution,the yield of lead oxide products could reach up to 94.4%when the molar ratio of NaOH to lead in filtrate was 2.5.This novel green method could shed light on the reuse of lead from exhausted ash with a much more convenient and environmentally friendly procedure.
文摘Samaras or winged seeds spread themselves by wind. Ash seed, unlike other samaras, has a high aspect ratio wing which can generate enough lift force to slow down descent by rotating about the vertical axis and spinning around its wing span axis simultaneously. This unique kinematics and inherent fluid mechanism are definitely of great interest. Detailed kinematics of free falling ash seeds were measured using high-speed cameras, then corresponding aerodynamic forces and moments were calculated employing computational fluid dynamics. The results show that both rotating and spinning directions are in the same side and the spinning angular velocity is about 6 times of rotating speed. The terminal descending velocity and cone angles are similar to other samaras. Analysis of the forces and moments shows that the lift is enough to balance the weight and the vertical rotation results from a processional motion of total angular moment because the spin-cycle-averaged aer-odynamic moment is perpendicular to the total angular moment and can only change its direction but maintain its magnitude, which is very similar to a spinning top in processional motion except that the total angular moment of ash seed is not along the spin axis but almost normal to it. The flow structures show that both leading and trailing edge vortices contribute to lift generation and the spanwise spinning results in an augmentation of the lift, implying that ash seeds with high aspect ratio wing may evolve in a different way in utilizing fluid mechanisms to facilitate dispersal.
