The effects of shear strength on aggregation flotation processes for fine spodumene(particle size less than 19μm)were investigated in this study.Sodium oleate was used as a surfactant and collector.The shear strength...The effects of shear strength on aggregation flotation processes for fine spodumene(particle size less than 19μm)were investigated in this study.Sodium oleate was used as a surfactant and collector.The shear strength was controlled by varying the agitation speed of a selfmade stirring apparatus.The aggregation process was studied by measuring the continuous transformations in the size distribution and shape of flocs.The results showed that as the shear strength increased,the distribution of fine spodumene transformed from bimodal to unimodal mode.The flocs tended to bridge more branches with a high shear strength and form globule-like flocs with very high strengths.The parameter"aggregation degree"was introduced to evaluate the aggregation process as a function of shear strength.The flotation rate of flocs formed with different shear strengths was also studied.These results demonstrated that the flotation rate was closely related to shear strength and that there was a close correlation between this and aggregation degree.These results could be used to guide the actual production of fine particles via shear aggregation flotation.展开更多
Climate and weather-propelled wind power is characterized by significant spatial and temporal variability.It has been substantiated that the variability of wind power,in addition to contributing hugely to the instabil...Climate and weather-propelled wind power is characterized by significant spatial and temporal variability.It has been substantiated that the variability of wind power,in addition to contributing hugely to the instability of power grids,can also send the balancing costs of electricity markets soaring.Existing studies on the same establish that curtailment of such variability can be achieved through the geographic aggregation of various widespread production sites;however,there exists a dearth of comprehensive evaluation concerning different levels/scales of such aggregation,especially from a global perspective.This paper primarily offers a fundamental understanding of the relationship between the wind power variations and aggregations from a systematic viewpoint based on extensive wind power data,thereby enabling the benefits of these aggregations to be quantified from a state scale ranging up to a global scale.Firstly,a meticulous analysis of the wind power variations is undertaken at 6 different levels by converting the 7-year hourly meteorological re-analysis data with a high spatial resolution of 0.25◦×0.25◦(approximate 28 km×28 km)into a wind power series globally.Subsequently,the proposed assessment framework employs a coefficient of variation of wind power as well as a standard deviation of wind power ramping rate to quantify the variations of wind power and wind power ramping rate to exhibit the characteristics and benefits yielded by the wind power aggregation at 6 different levels.A system planning example is adopted to illustrate the correlation between the coefficient of variation reduction of wind power and investment reduction,thereby emphasizing the benefits pertaining to significant investment reduction via aggregation.Furthermore,a wind power duration curve is used to exemplify the availability of wind power aggregated at different levels.Finally,the results provide insights into devising a universal approach towards the deployment of wind power,principally along the lines of Net-Zero.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51574240)the Natural Science Foundation of Jiangxi Province,China(Nos.20181BBG70050 and 20171BBG70044).
文摘The effects of shear strength on aggregation flotation processes for fine spodumene(particle size less than 19μm)were investigated in this study.Sodium oleate was used as a surfactant and collector.The shear strength was controlled by varying the agitation speed of a selfmade stirring apparatus.The aggregation process was studied by measuring the continuous transformations in the size distribution and shape of flocs.The results showed that as the shear strength increased,the distribution of fine spodumene transformed from bimodal to unimodal mode.The flocs tended to bridge more branches with a high shear strength and form globule-like flocs with very high strengths.The parameter"aggregation degree"was introduced to evaluate the aggregation process as a function of shear strength.The flotation rate of flocs formed with different shear strengths was also studied.These results demonstrated that the flotation rate was closely related to shear strength and that there was a close correlation between this and aggregation degree.These results could be used to guide the actual production of fine particles via shear aggregation flotation.
基金This work was supported partly by the Engineering and Physical Sciences Research Council(EPSRC)under Grant EP/N032888/1 and Grant EP/L017725/1by GEIDCO under Grant 1474100.
文摘Climate and weather-propelled wind power is characterized by significant spatial and temporal variability.It has been substantiated that the variability of wind power,in addition to contributing hugely to the instability of power grids,can also send the balancing costs of electricity markets soaring.Existing studies on the same establish that curtailment of such variability can be achieved through the geographic aggregation of various widespread production sites;however,there exists a dearth of comprehensive evaluation concerning different levels/scales of such aggregation,especially from a global perspective.This paper primarily offers a fundamental understanding of the relationship between the wind power variations and aggregations from a systematic viewpoint based on extensive wind power data,thereby enabling the benefits of these aggregations to be quantified from a state scale ranging up to a global scale.Firstly,a meticulous analysis of the wind power variations is undertaken at 6 different levels by converting the 7-year hourly meteorological re-analysis data with a high spatial resolution of 0.25◦×0.25◦(approximate 28 km×28 km)into a wind power series globally.Subsequently,the proposed assessment framework employs a coefficient of variation of wind power as well as a standard deviation of wind power ramping rate to quantify the variations of wind power and wind power ramping rate to exhibit the characteristics and benefits yielded by the wind power aggregation at 6 different levels.A system planning example is adopted to illustrate the correlation between the coefficient of variation reduction of wind power and investment reduction,thereby emphasizing the benefits pertaining to significant investment reduction via aggregation.Furthermore,a wind power duration curve is used to exemplify the availability of wind power aggregated at different levels.Finally,the results provide insights into devising a universal approach towards the deployment of wind power,principally along the lines of Net-Zero.
