Almost 29.57–38.46 million tons of zinc-bearing dust were produced in Chinese iron and steel enterprises annually.The recovery of Zn and other metals in zinc-bearing dust from ironmaking and steelmaking could improve...Almost 29.57–38.46 million tons of zinc-bearing dust were produced in Chinese iron and steel enterprises annually.The recovery of Zn and other metals in zinc-bearing dust from ironmaking and steelmaking could improve economic efficiency.However,zinc-bearing dust was classified as hazardous waste,and the volatile metals(like Zn,Na,Pb,etc.)in zinc-bearing dust limited the direct reusing in a blast furnace.Therefore,the formation process,fundamental characteristics,and current extraction process of Zn from zinc-bearing dust,associated with thermodynamics and kinetics of the pyrometallurgical process,hydrometallurgical process,and pyro-hydrometallurgical process,were analyzed.It is indicated that industrialized pyrometallurgical processes are undergoing high energy consumption and pollution such as rotary kiln and rotary hearth furnace process.The vacuum carbothermal reduction process can realize low carbon emission and no waste produced in the process.The hydrometallurgical leaching processes in strong acid,strong alkali,and ammonium solutions result in serious liquid pollution and equipment corrosion.The pyrometallurgical process involves complex kinetics and lacks kinetic research on semi-industrialization and industrialization.Water-soluble components in zinc-bearing dust can be removed by water leaching.The kinetics of the strong acid leaching is mainly controlled by the leaching kinetics of Fe_(2)O_(3) and ZnFe_(2)O_(4),while the alkali leaching and weak acid leaching are controlled by the kinetics of ZnO leaching.Zn in the zincbearing dust can be extracted by a low-temperature sodium roasting–weak acid leaching process that reduces equipment corrosion and environmental pollution.展开更多
Large amounts of solid wastes and flue gases are generated in iron and steel production process,probably leading to serious environmental pollution without duly handle.An innovative and green process of simultaneous r...Large amounts of solid wastes and flue gases are generated in iron and steel production process,probably leading to serious environmental pollution without duly handle.An innovative and green process of simultaneous reduction of zinc-bearing dusts and activation of low-rank coal was developed and its mechanism was clarified in this paper.Under the optimal conditions,the reduced zinc-bearing dusts containing low harmful elements(0.02%Zn,0.015%K and 0.03%Na)could be made as high-quality burden for blast furnace while the low-rank coal was transferred into K,Na-embedded activated carbon,which can be used as effective adsorbent for purification of SO_(2) and NO-containing flue gases.The solid wastes were successfully utilized to treat the flue gases through the process.The synergetic activation and reduction mechanism in the process was revealed.The coupling effect between reduction reactions of metal oxides in the dusts and activation reaction of carbon in the coal promoted the simultaneous reduction and activation process.In the meanwhile,part of the potassium and sodium from the zinc-bearing dusts could be adsorbed by the activated carbon and played a catalytic role in the activation process.展开更多
It is urgent to dispose of zinc-bearing dust from steel plants,and direct reduction process is an effective method to remove hazardous metals and recycle iron from the dust.The reduction behavior of carbon-containing ...It is urgent to dispose of zinc-bearing dust from steel plants,and direct reduction process is an effective method to remove hazardous metals and recycle iron from the dust.The reduction behavior of carbon-containing pellets which were made from three kinds of zinc-bearing dust was investigated.When the pellets were reduced at 1200℃ for 50 min,the reduced pellets with cold compressive strength of 1164 N pellet−1 and Zn content<0.1 wt.%could be directly used as burden for improving the blast furnace operation without further agglomeration.The results of isothermal kinetic study showed that the iron oxide reduction rate was controlled by the chemical reactions.The strengthening mechanism of reduced pellets and iron oxide reduction mechanism was investigated by thermodynamic calculation besides X-ray diffraction,scanning electron microscopy combined with energy dispersive spectrometry,and optical microscopy analyses.It was found that higher temperatures are required for the reduction of spinel phase(zinc ferrite)and olivine phase(hedenbergite).The generation and growth of metallic iron bridges could significantly increase the compressive strength of reduced pellets.The iron oxide reduction in the carbon-containing pellets followed the uniform internal reduction model and possessed a high apparent reaction rate,which can improve energy utilization rate and production efficiency.展开更多
基金support from the National Natural Science Foundation of China(Grant No.52064010)Outstanding Young Scientists and Technologists Program of Guizhou Province,China(Grant No.[2021]5644)+1 种基金the Key Nurturing Projects of Guizhou University(Grant No.[2019]07)the Natural Science Research Project of Guizhou Provincial Department of Education([2022]041).
文摘Almost 29.57–38.46 million tons of zinc-bearing dust were produced in Chinese iron and steel enterprises annually.The recovery of Zn and other metals in zinc-bearing dust from ironmaking and steelmaking could improve economic efficiency.However,zinc-bearing dust was classified as hazardous waste,and the volatile metals(like Zn,Na,Pb,etc.)in zinc-bearing dust limited the direct reusing in a blast furnace.Therefore,the formation process,fundamental characteristics,and current extraction process of Zn from zinc-bearing dust,associated with thermodynamics and kinetics of the pyrometallurgical process,hydrometallurgical process,and pyro-hydrometallurgical process,were analyzed.It is indicated that industrialized pyrometallurgical processes are undergoing high energy consumption and pollution such as rotary kiln and rotary hearth furnace process.The vacuum carbothermal reduction process can realize low carbon emission and no waste produced in the process.The hydrometallurgical leaching processes in strong acid,strong alkali,and ammonium solutions result in serious liquid pollution and equipment corrosion.The pyrometallurgical process involves complex kinetics and lacks kinetic research on semi-industrialization and industrialization.Water-soluble components in zinc-bearing dust can be removed by water leaching.The kinetics of the strong acid leaching is mainly controlled by the leaching kinetics of Fe_(2)O_(3) and ZnFe_(2)O_(4),while the alkali leaching and weak acid leaching are controlled by the kinetics of ZnO leaching.Zn in the zincbearing dust can be extracted by a low-temperature sodium roasting–weak acid leaching process that reduces equipment corrosion and environmental pollution.
基金the National Natural Science Foundation of China (No. 51574281), which supplied us with the facilities and funds needed to completed the experiments
文摘Large amounts of solid wastes and flue gases are generated in iron and steel production process,probably leading to serious environmental pollution without duly handle.An innovative and green process of simultaneous reduction of zinc-bearing dusts and activation of low-rank coal was developed and its mechanism was clarified in this paper.Under the optimal conditions,the reduced zinc-bearing dusts containing low harmful elements(0.02%Zn,0.015%K and 0.03%Na)could be made as high-quality burden for blast furnace while the low-rank coal was transferred into K,Na-embedded activated carbon,which can be used as effective adsorbent for purification of SO_(2) and NO-containing flue gases.The solid wastes were successfully utilized to treat the flue gases through the process.The synergetic activation and reduction mechanism in the process was revealed.The coupling effect between reduction reactions of metal oxides in the dusts and activation reaction of carbon in the coal promoted the simultaneous reduction and activation process.In the meanwhile,part of the potassium and sodium from the zinc-bearing dusts could be adsorbed by the activated carbon and played a catalytic role in the activation process.
基金The authors wish to thank the National Natural Science Foundation of China(No.51904347),which supplied us with the facilities and funds needed to complete the experiments.
文摘It is urgent to dispose of zinc-bearing dust from steel plants,and direct reduction process is an effective method to remove hazardous metals and recycle iron from the dust.The reduction behavior of carbon-containing pellets which were made from three kinds of zinc-bearing dust was investigated.When the pellets were reduced at 1200℃ for 50 min,the reduced pellets with cold compressive strength of 1164 N pellet−1 and Zn content<0.1 wt.%could be directly used as burden for improving the blast furnace operation without further agglomeration.The results of isothermal kinetic study showed that the iron oxide reduction rate was controlled by the chemical reactions.The strengthening mechanism of reduced pellets and iron oxide reduction mechanism was investigated by thermodynamic calculation besides X-ray diffraction,scanning electron microscopy combined with energy dispersive spectrometry,and optical microscopy analyses.It was found that higher temperatures are required for the reduction of spinel phase(zinc ferrite)and olivine phase(hedenbergite).The generation and growth of metallic iron bridges could significantly increase the compressive strength of reduced pellets.The iron oxide reduction in the carbon-containing pellets followed the uniform internal reduction model and possessed a high apparent reaction rate,which can improve energy utilization rate and production efficiency.
