Extracting rare earth elements(REEs)from coal refuse is challenging due to their low co ncentrations and poor leachability.Bioleaching has emerged as a sustainable technology to recover REEs from low-grade materials.I...Extracting rare earth elements(REEs)from coal refuse is challenging due to their low co ncentrations and poor leachability.Bioleaching has emerged as a sustainable technology to recover REEs from low-grade materials.In this study,a ferric sulfate bio acid(BA)with an acidity of~0.2 mol/L H^(+),generated through regulated pyrite bio-oxidation,was used to leach REEs and critical metals(CMs)from coal refuse(ground to<1 mm)after 20-min roasting at 600℃.The influences of solid/liquid(S/L)ratio(100-300 g/L)and leaching temperature(25-95℃)on the leaching performance were examined.The leaching mechanisms were investigated by conducting stepwise precipitation tests and spectroscopic characterization.Results show that raising the leaching temperature to≥65℃accelerated the REE leaching kinetics but causes the loss of light REEs(LREEs)after reaching peak values at 30-60 min.Stage precipitation tests reveal that the loss is due to the incorporation of REEs,especially for LREEs,by gypsum and schwertmannite.The peak total REE(TREE)recovery of the BA leaching reaches 24.9%after 30 min of leaching at75℃with a S/L ratio of 200 g/L.Implementing the three-stage counter-current leaching increases the overall TREE recovery to 31.8%by recovering the REEs incorporated in the Fe and Ca precipitates.Meanwhile,promising recovery values of Li(55.5%),Mn(74.6%),Ni(41.6%),and Co(35.3%)are also achieved.This method provides a sustainable approach to extract REEs and critical metals from coal waste materials with a high treatment capacity.展开更多
To overcome the limited mixing efficiency associated with conventional steady-state side blowing in molten pool smelting,this study proposes a gas injection strategy that combines a swirl lance configuration with sinu...To overcome the limited mixing efficiency associated with conventional steady-state side blowing in molten pool smelting,this study proposes a gas injection strategy that combines a swirl lance configuration with sinusoidal pulsed blowing.Using a volume-of-fluid(VOF)multiphase flow framework coupled with the Realizable k-ε turbulence model,the performance of constant-velocity blowing is systematically compared with sinusoidal pulsed blowing over a range of amplitudes(5,10,and 15 m/s)and frequencies(0.5,1,and 2 Hz).The results demonstrate that sinusoidal pulsed blowing markedly enhances gas-liquid mixing within the melt pool relative to constant-speed injection.Mixing efficiency increases with blowing amplitude,while its dependence on pulse frequency is nonlinear.Within the investigated parameter space,the optimal configuration,an amplitude of 15 m/s and a frequency of 1 Hz,raises the average gas volume fraction by 8%,reduces the mixing dead-zone area by 81%,and expands the active mixing region by 25%.Overall,the imposed sinusoidal pulsing promotes bubble breakup beneath the free surface,leading to more complete bubble collapse,intensified turbulent agitation,and,ultimately,improved gas–liquid mixing.展开更多
文摘Extracting rare earth elements(REEs)from coal refuse is challenging due to their low co ncentrations and poor leachability.Bioleaching has emerged as a sustainable technology to recover REEs from low-grade materials.In this study,a ferric sulfate bio acid(BA)with an acidity of~0.2 mol/L H^(+),generated through regulated pyrite bio-oxidation,was used to leach REEs and critical metals(CMs)from coal refuse(ground to<1 mm)after 20-min roasting at 600℃.The influences of solid/liquid(S/L)ratio(100-300 g/L)and leaching temperature(25-95℃)on the leaching performance were examined.The leaching mechanisms were investigated by conducting stepwise precipitation tests and spectroscopic characterization.Results show that raising the leaching temperature to≥65℃accelerated the REE leaching kinetics but causes the loss of light REEs(LREEs)after reaching peak values at 30-60 min.Stage precipitation tests reveal that the loss is due to the incorporation of REEs,especially for LREEs,by gypsum and schwertmannite.The peak total REE(TREE)recovery of the BA leaching reaches 24.9%after 30 min of leaching at75℃with a S/L ratio of 200 g/L.Implementing the three-stage counter-current leaching increases the overall TREE recovery to 31.8%by recovering the REEs incorporated in the Fe and Ca precipitates.Meanwhile,promising recovery values of Li(55.5%),Mn(74.6%),Ni(41.6%),and Co(35.3%)are also achieved.This method provides a sustainable approach to extract REEs and critical metals from coal waste materials with a high treatment capacity.
基金Supported by Yunnan Fundamental Research Projects(202301AT070469,202301AT070275)Supported by Yunnan Provincial Integrated Special Fund for Key Laboratories(Integrated for Provincial and Municipal Levels)(No.202302AN360004).
文摘To overcome the limited mixing efficiency associated with conventional steady-state side blowing in molten pool smelting,this study proposes a gas injection strategy that combines a swirl lance configuration with sinusoidal pulsed blowing.Using a volume-of-fluid(VOF)multiphase flow framework coupled with the Realizable k-ε turbulence model,the performance of constant-velocity blowing is systematically compared with sinusoidal pulsed blowing over a range of amplitudes(5,10,and 15 m/s)and frequencies(0.5,1,and 2 Hz).The results demonstrate that sinusoidal pulsed blowing markedly enhances gas-liquid mixing within the melt pool relative to constant-speed injection.Mixing efficiency increases with blowing amplitude,while its dependence on pulse frequency is nonlinear.Within the investigated parameter space,the optimal configuration,an amplitude of 15 m/s and a frequency of 1 Hz,raises the average gas volume fraction by 8%,reduces the mixing dead-zone area by 81%,and expands the active mixing region by 25%.Overall,the imposed sinusoidal pulsing promotes bubble breakup beneath the free surface,leading to more complete bubble collapse,intensified turbulent agitation,and,ultimately,improved gas–liquid mixing.
