Red mud, an insoluble residue produced during alkali leaching of bauxite, is considered as a low-grade iron ore containing 30% to 50% iron. The present paper deals with the use of thermal plasma technology for produci...Red mud, an insoluble residue produced during alkali leaching of bauxite, is considered as a low-grade iron ore containing 30% to 50% iron. The present paper deals with the use of thermal plasma technology for producing pig iron from red mud waste fines. The smelting reduction of red mud was carried out in a 35 kW DC extended arc thermal plasma reactor. Red mud was properly mixed with fluxes and graphite （fixed carbon, 99%） as a reductant as per stoichiometric requirement. The effect of various process parameters like a reductant, fluxes and smelting time on iron recovery was studied and optimized. An optimum condition for the maximum recovery of iron was obtained. A new thermal plasma process applicable to direct iron making from red mud waste fines that would achieve significant utilization of red mud was proposed.展开更多
Y2O3 stabilized ZrO2(YSZ)thermal barrier coatings(TBCs)are prone to hot corrosion by molten salts.In this study,the microstructure of atmospheric plasma spraying YSZ TBCs is modified by laser glazing in order to impro...Y2O3 stabilized ZrO2(YSZ)thermal barrier coatings(TBCs)are prone to hot corrosion by molten salts.In this study,the microstructure of atmospheric plasma spraying YSZ TBCs is modified by laser glazing in order to improve the corrosion resistance.By optimizing the laser parameters,a^18μm smooth glazed layer with some vertical cracks was produced on the coating surfaces.The as-sprayed and modified coatings were both exposed to hot corrosion tests at 700 and 1000℃for 4 h in V2O5 molten salt,and the results revealed that the modified one had improved corrosion resistance.After hot corrosion,the glazed layer kept structural integrity,with little evidence of dissolution.However,the vertical cracks in the glazed layer acted as the paths for molten salt penetration,accelerating the corrosion of the non-modified coating.Further optimization of the glazed layer is needed in the future work.展开更多
Volatile organic compounds(VOCs)released from the waste treatment facilities have become a significant issue because they are not only causing odor nuisance but may also hazard to human health.Non-thermal plasma(NTP)t...Volatile organic compounds(VOCs)released from the waste treatment facilities have become a significant issue because they are not only causing odor nuisance but may also hazard to human health.Non-thermal plasma(NTP)technologies are newly developed methods and became a research trend in recent years regarding the removal of VOCs from the air stream.Due to its unique characteristics,such as rapid response at room temperature,bulk homogenized volume,high reaction efficiency,dielectric barrier discharge(DBD)plasma technology is considered one of the most promising techniques of NTP.This paper reviews recent progress of DBD plasma technology for abatement of VOCs.The principle of plasma generation in DBD and its configurations(electrode,discharge gap,dielectric barrier material,etc.)are discussed in details.Based on previously published literature,attention has been paid on the effect of DBD configuration on the removal of VOCs.Effect of various process parameters such as initial concentration,gas feeding rate,oxygen content and input power on VOCs removal are also considered.Moreover,the role of catalysis and inhibitors in VOCs removal by DBD system are presented.Finally,a modified configuration of the DBD reactor,i.e.double dielectric barrier discharge(DDBD)for the abatement of VOCs is discussed.It was suggested that the DDBD plasma reactor could be used for higher conversion efficiency as well as for avoiding solid residue deposition on the electrode.These depositions can interfere with the performance of the reactor.展开更多
α‐,β‐,γ‐andδ‐MnO2catalysts were synthesized by a one‐step hydrothermal method,and were utilized for the catalytic oxidation of toluene in a combined plasma‐catalytic process.The relationship between catalyti...α‐,β‐,γ‐andδ‐MnO2catalysts were synthesized by a one‐step hydrothermal method,and were utilized for the catalytic oxidation of toluene in a combined plasma‐catalytic process.The relationship between catalytic performance and MnO2crystal structures was investigated.It was noted that the toluene removal efficiency was32.5%at the specific input energy of160J/L when non‐thermal plasma was used alone.Theα‐MnO2catalyst showed the best activity among the investigated catalysts,yielding a toluene conversion of78.1%at the specific input energy of160J/L.Forβ‐MnO2,γ‐MnO2andδ‐MnO2,removal efficiencies of47.4%,66.1%and50.0%,respectively,were achieved.By powder X‐ray diffraction,Raman spectroscopy,transmission electron microscopy,scanning electron microscopy,Brunauer‐Emmett‐Teller,H2temperature‐programmed reduction and X‐ray photoelectron spectroscopy analyses,it was concluded that the tunnel structure,the stability of the crystal in plasma,the Mn-O bond strength of MnO2and the surface‐chemisorbed oxygen species played important roles in the plasma‐catalytic degradation of toluene.Additionally,the degradation routes of toluene in non‐thermal plasma and in the plasma‐catalytic process were also studied.It was concluded that the introduction of MnO2catalysts enabled O3,O2,electrons and radical species in the gas to be adsorbed on the MnO2surface via a facile interconversion among the Mn4+,Mn3+and Mn2+states.These four species could then be transported to the toluene or intermediate organic by‐products,which greatly improved the toluene removal efficiency and decreased the final output of by‐products.展开更多
文摘Red mud, an insoluble residue produced during alkali leaching of bauxite, is considered as a low-grade iron ore containing 30% to 50% iron. The present paper deals with the use of thermal plasma technology for producing pig iron from red mud waste fines. The smelting reduction of red mud was carried out in a 35 kW DC extended arc thermal plasma reactor. Red mud was properly mixed with fluxes and graphite （fixed carbon, 99%） as a reductant as per stoichiometric requirement. The effect of various process parameters like a reductant, fluxes and smelting time on iron recovery was studied and optimized. An optimum condition for the maximum recovery of iron was obtained. A new thermal plasma process applicable to direct iron making from red mud waste fines that would achieve significant utilization of red mud was proposed.
基金This research is sponsored by the National Natural Science Foundation of China(Grant No.51971156).
文摘Y2O3 stabilized ZrO2(YSZ)thermal barrier coatings(TBCs)are prone to hot corrosion by molten salts.In this study,the microstructure of atmospheric plasma spraying YSZ TBCs is modified by laser glazing in order to improve the corrosion resistance.By optimizing the laser parameters,a^18μm smooth glazed layer with some vertical cracks was produced on the coating surfaces.The as-sprayed and modified coatings were both exposed to hot corrosion tests at 700 and 1000℃for 4 h in V2O5 molten salt,and the results revealed that the modified one had improved corrosion resistance.After hot corrosion,the glazed layer kept structural integrity,with little evidence of dissolution.However,the vertical cracks in the glazed layer acted as the paths for molten salt penetration,accelerating the corrosion of the non-modified coating.Further optimization of the glazed layer is needed in the future work.
文摘Volatile organic compounds(VOCs)released from the waste treatment facilities have become a significant issue because they are not only causing odor nuisance but may also hazard to human health.Non-thermal plasma(NTP)technologies are newly developed methods and became a research trend in recent years regarding the removal of VOCs from the air stream.Due to its unique characteristics,such as rapid response at room temperature,bulk homogenized volume,high reaction efficiency,dielectric barrier discharge(DBD)plasma technology is considered one of the most promising techniques of NTP.This paper reviews recent progress of DBD plasma technology for abatement of VOCs.The principle of plasma generation in DBD and its configurations(electrode,discharge gap,dielectric barrier material,etc.)are discussed in details.Based on previously published literature,attention has been paid on the effect of DBD configuration on the removal of VOCs.Effect of various process parameters such as initial concentration,gas feeding rate,oxygen content and input power on VOCs removal are also considered.Moreover,the role of catalysis and inhibitors in VOCs removal by DBD system are presented.Finally,a modified configuration of the DBD reactor,i.e.double dielectric barrier discharge(DDBD)for the abatement of VOCs is discussed.It was suggested that the DDBD plasma reactor could be used for higher conversion efficiency as well as for avoiding solid residue deposition on the electrode.These depositions can interfere with the performance of the reactor.
基金supported by the National Key Research and Development Plan of China(2016YFC0204700)Zhejiang Provincial"151"Talents Program(2013)+2 种基金Key Project of Zhejiang Provincial Science and Technology Program,the Program for Zhejiang Leading Team of S&T Innovation(2013TD07)Special Program for Social Development of Key Science and Technology Project of Zhejiang Province(2014C03025)Changjiang Scholar Incentive Program(2009)~~
文摘α‐,β‐,γ‐andδ‐MnO2catalysts were synthesized by a one‐step hydrothermal method,and were utilized for the catalytic oxidation of toluene in a combined plasma‐catalytic process.The relationship between catalytic performance and MnO2crystal structures was investigated.It was noted that the toluene removal efficiency was32.5%at the specific input energy of160J/L when non‐thermal plasma was used alone.Theα‐MnO2catalyst showed the best activity among the investigated catalysts,yielding a toluene conversion of78.1%at the specific input energy of160J/L.Forβ‐MnO2,γ‐MnO2andδ‐MnO2,removal efficiencies of47.4%,66.1%and50.0%,respectively,were achieved.By powder X‐ray diffraction,Raman spectroscopy,transmission electron microscopy,scanning electron microscopy,Brunauer‐Emmett‐Teller,H2temperature‐programmed reduction and X‐ray photoelectron spectroscopy analyses,it was concluded that the tunnel structure,the stability of the crystal in plasma,the Mn-O bond strength of MnO2and the surface‐chemisorbed oxygen species played important roles in the plasma‐catalytic degradation of toluene.Additionally,the degradation routes of toluene in non‐thermal plasma and in the plasma‐catalytic process were also studied.It was concluded that the introduction of MnO2catalysts enabled O3,O2,electrons and radical species in the gas to be adsorbed on the MnO2surface via a facile interconversion among the Mn4+,Mn3+and Mn2+states.These four species could then be transported to the toluene or intermediate organic by‐products,which greatly improved the toluene removal efficiency and decreased the final output of by‐products.
