The utilization of arsenic-containing gold dressing tailings is an urgent issue faced by gold production companies worldwide.The thermodynamic analysis results indicate that ferrous arsenate(FeAsO_(4)),pyrite(FeS_(2))...The utilization of arsenic-containing gold dressing tailings is an urgent issue faced by gold production companies worldwide.The thermodynamic analysis results indicate that ferrous arsenate(FeAsO_(4)),pyrite(FeS_(2))and sodium cyanide(NaCN)in the arsenic-containing gold metallurgical tailings can be effectively removed using straight grate process,and the removal of pyrite and sodium cyanide is basically completed during the preheating stage,while the removal of ferrous arsenate requires the roasting stage.The pellets undergo a transformation from magnetite to hematite during the preheating process,and are solidified through micro-crystalline bonding and high-temperature recrystallization of hematite(Fe_(2)O_(3))during the roasting process.Ultimately,pellets with removal rates of 80.77% for arsenic,88.78% for sulfur,and 99.88% for cyanide are obtained,as well as the iron content is 61.1% and the compressive strength is 3071 N,meeting the requirements for blast furnace burden.This study provides an industrially feasible method for treating arsenic-containing gold smelting tailings,benefiting gold production enterprises.展开更多
The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-...The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-feed machine.In order to develop such a machine,3D-modeling and machine simulations were performed and a twin wheel creep-feed grinding machine was manufactured.Furthermore,the axisymmetric precision of the machined workpieces through practical machining was evaluated and the quality of the continuous dressing effect of the developed machine was established.In addition,experimental considerations for a proper dresser-to-wheel speed ratio and proper feed rate of the dresser were carried out.As a result,a twin wheel creep-feed grinding machine with continuous dressing is developed through machine simulation,manufacturing and performance evaluation.Optimum condition for the dresser feed rate is 0.3μm/rev.In cases of large dressor-to-wheel speed ratio,grinding efficiency can be enhanced,but the surface roughness shows a conflicting trend.Developed twin wheel creep-feed grinding machine has satisfactory appraisal with regard to surface roughness,flatness,and parallelism.Satisfactory surface roughness below 0.1μm can be obtained for the blade of aircraft.However,in order to perform precise machining,it is necessary to improve the structure of the twin wheel creep-feed grinding machine.展开更多
Worm grinding has been applied to manufacture gears to pursue high accuracy and fine surface finish.When the worm used to grind face gears is manufactured with multi-axis computer numerical control(CNC)machining,the m...Worm grinding has been applied to manufacture gears to pursue high accuracy and fine surface finish.When the worm used to grind face gears is manufactured with multi-axis computer numerical control(CNC)machining,the machining accuracy is usually improved by increasing the number of tool paths with more time cost.Differently,this work proposes a generated method to improve the efficiency by dressing the worm surface with only one path,and a closed-loop manufacturing process is applied to ensure the machining accuracy.According to an advanced geometric analysis,the worm surface is practically approximated as a swept surface generated by a planar curve.Meanwhile,this curve is applied as the profile of a dressing wheel,which is used to dress the worm surface.The practical machining is carried out in a CNC machine tool,which was originally used to grind helical gears.Finally,a closed-loop manufacturing process including machining,measurement,and modification is proposed to compensate the machining errors.The proposed method is validated with simulations and practical experiments.展开更多
The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinui...The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinuities on the active surface）. Using these background details, a suggested thesis was put forward regarding the need to develop a device which will allow for the shaping of the macrogeometry of the grinding wheel （cylindrical and conical surfaces） and the microdiscontinuities within the dressing operation simultaneously. The device was presented and prepared in two functional variants （horizontal and vertical mounting of the motor）, then a prototype was described. An example of the grinding wheel active surface, shaped by using this device, was also presented. The theoretical analysis and experimental verification performed determine that the error of shaping the conic chamfer angle within the range of 0-1.5°, using the developed device, is approximately ±3%.展开更多
The CHIMEHERB artificial skin developed by Ocean University of Qingdao was a gold medelwinner both at the 37th Eureka World Fair for Inventions in 1988 and at the First International Ex-hibition of Patent and New Tech...The CHIMEHERB artificial skin developed by Ocean University of Qingdao was a gold medelwinner both at the 37th Eureka World Fair for Inventions in 1988 and at the First International Ex-hibition of Patent and New Technological Product. The laboratorial work of the artificial skin beganin 1983. In April 1986, clinical applications were carried out in the surgical, dermatological andburn wounds in various hospitals such as Shandong Central Hospital, Affiliated Hospital of Shan-展开更多
基金Project(52274343)supported by the National Natural Science Foundation of ChinaProjects(2023YFC3903900,2023YFC3903904)supported by the National Key R&D Program of China。
文摘The utilization of arsenic-containing gold dressing tailings is an urgent issue faced by gold production companies worldwide.The thermodynamic analysis results indicate that ferrous arsenate(FeAsO_(4)),pyrite(FeS_(2))and sodium cyanide(NaCN)in the arsenic-containing gold metallurgical tailings can be effectively removed using straight grate process,and the removal of pyrite and sodium cyanide is basically completed during the preheating stage,while the removal of ferrous arsenate requires the roasting stage.The pellets undergo a transformation from magnetite to hematite during the preheating process,and are solidified through micro-crystalline bonding and high-temperature recrystallization of hematite(Fe_(2)O_(3))during the roasting process.Ultimately,pellets with removal rates of 80.77% for arsenic,88.78% for sulfur,and 99.88% for cyanide are obtained,as well as the iron content is 61.1% and the compressive strength is 3071 N,meeting the requirements for blast furnace burden.This study provides an industrially feasible method for treating arsenic-containing gold smelting tailings,benefiting gold production enterprises.
基金Work supported by the Second Stage of Brain Korea 21 Project
文摘The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-feed machine.In order to develop such a machine,3D-modeling and machine simulations were performed and a twin wheel creep-feed grinding machine was manufactured.Furthermore,the axisymmetric precision of the machined workpieces through practical machining was evaluated and the quality of the continuous dressing effect of the developed machine was established.In addition,experimental considerations for a proper dresser-to-wheel speed ratio and proper feed rate of the dresser were carried out.As a result,a twin wheel creep-feed grinding machine with continuous dressing is developed through machine simulation,manufacturing and performance evaluation.Optimum condition for the dresser feed rate is 0.3μm/rev.In cases of large dressor-to-wheel speed ratio,grinding efficiency can be enhanced,but the surface roughness shows a conflicting trend.Developed twin wheel creep-feed grinding machine has satisfactory appraisal with regard to surface roughness,flatness,and parallelism.Satisfactory surface roughness below 0.1μm can be obtained for the blade of aircraft.However,in order to perform precise machining,it is necessary to improve the structure of the twin wheel creep-feed grinding machine.
基金Project(2019 YFB 2004700)supported by the National Key R&D Project of ChinaProject(HTL-O-19 K 02)supported by National Key Laboratory of Science and Technology on Helicopter Transmission,Nanjing University of Aeronautics and Astronautics,China。
文摘Worm grinding has been applied to manufacture gears to pursue high accuracy and fine surface finish.When the worm used to grind face gears is manufactured with multi-axis computer numerical control(CNC)machining,the machining accuracy is usually improved by increasing the number of tool paths with more time cost.Differently,this work proposes a generated method to improve the efficiency by dressing the worm surface with only one path,and a closed-loop manufacturing process is applied to ensure the machining accuracy.According to an advanced geometric analysis,the worm surface is practically approximated as a swept surface generated by a planar curve.Meanwhile,this curve is applied as the profile of a dressing wheel,which is used to dress the worm surface.The practical machining is carried out in a CNC machine tool,which was originally used to grind helical gears.Finally,a closed-loop manufacturing process including machining,measurement,and modification is proposed to compensate the machining errors.The proposed method is validated with simulations and practical experiments.
文摘The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinuities on the active surface）. Using these background details, a suggested thesis was put forward regarding the need to develop a device which will allow for the shaping of the macrogeometry of the grinding wheel （cylindrical and conical surfaces） and the microdiscontinuities within the dressing operation simultaneously. The device was presented and prepared in two functional variants （horizontal and vertical mounting of the motor）, then a prototype was described. An example of the grinding wheel active surface, shaped by using this device, was also presented. The theoretical analysis and experimental verification performed determine that the error of shaping the conic chamfer angle within the range of 0-1.5°, using the developed device, is approximately ±3%.
文摘The CHIMEHERB artificial skin developed by Ocean University of Qingdao was a gold medelwinner both at the 37th Eureka World Fair for Inventions in 1988 and at the First International Ex-hibition of Patent and New Technological Product. The laboratorial work of the artificial skin beganin 1983. In April 1986, clinical applications were carried out in the surgical, dermatological andburn wounds in various hospitals such as Shandong Central Hospital, Affiliated Hospital of Shan-
