A one-dimensional unsteady mathematical model was established to describe direct reduction in a composite pellet made of metallurgical dust. The model considered heat transfer, mass transfer, and chemical reactions in...A one-dimensional unsteady mathematical model was established to describe direct reduction in a composite pellet made of metallurgical dust. The model considered heat transfer, mass transfer, and chemical reactions including iron oxide reductions, zinc oxide reduction and carbon gasification, and it was numerically solved by the tridiagonal matrix algorithm (TDMA). In order to verify the model, an experiment was performed, in which the profiles of temperature and zinc removal rate were measured during the reduction process. Results calculated by the mathematical model were in fairly good agreement with experimental data. Finally, the effects of furnace temperature, pellet size, and carbon content were investigated by model calculations. It is found that the pellet temperature curve can be divided into four parts according to heating rate. Also, the zinc removal rate increases with the increase of furnace temperature and the decrease of pellet size, and carbon content in the pellet has little influence on the zinc removal rate.展开更多
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
A thermodynamic analysis on the acid leaching process of germanium oxide dust and discussion on the behaviors of main substances of the dust in the leaching process were carried out. The effects of temperature, acid c...A thermodynamic analysis on the acid leaching process of germanium oxide dust and discussion on the behaviors of main substances of the dust in the leaching process were carried out. The effects of temperature, acid concentration, leaching time and stirring speed on the leaching rate of germanium were investigated. Based on the characteristic of the dust, the kinetics and reactive mechanism of acid leaching were studied. The results show that the leaching of the dust by acid belonged to "the unreacted core shrinking model" of producing solid outgrowth layer. The chemical reaction was controlled by inner diffusion process. The apparent activation energy of leaching process was 12.60 kJ/mol. The leaching reaction of germanium was determined to be mainly second order reaction. The optimum conditions were the reaction temperature of 363 K, the leaching time of 2.5 h, the stirring speed of 120 r/min, the solid-to-liquid ratio of 1/8 and the acid concentration of 120 g/L. Under these conditions, the leaching rate of germanium can come up to more than 87%.展开更多
The agglomeration of solid wastes is a key factor for subsequent utilization,while the difficulty in agglomeration and high cost have become common problems in the recycling process.The disk pelletizing process was ad...The agglomeration of solid wastes is a key factor for subsequent utilization,while the difficulty in agglomeration and high cost have become common problems in the recycling process.The disk pelletizing process was adopted,based on the optimization method by liquid binder addition,and the influence mechanism of the ratio of typical solid wastes as blast furnace dust(BFD)and sludge generated by oxygen converter gas recovery(OGS)was explored.Meanwhile,the effect of binder solution concentration on the quality of green pellets was studied.Derived from the contact angle detection and infrared spectrum analysis,the liquid bridge model was established to study the bonding mechanism.The results showed that OGS had stronger adsorption effect with binder,and the hydrophilicity of BFD was better.When the concentration of binder was higher than 0.2 wt.%,the contact angle between the binder and BFD was bigger than that with OGS,while the capillary force between particles reduced with larger contact angle.The increment in the binder concentration increased the viscous force between particles and the maximum separation distance.The ultimate drop strength and compressive strength were related to the type of viscous force,and the compressive strength reflected the strength of the force between particles intuitively,while the drop strength represented the comprehensive forces of green pellets.Reasonable combination of BFD and OGS was available for pelletizing process,while the ratio of BFD should not exceed 32.0%,and binder C was added in the form of solution with the addition amount of 0.4 wt.%,which can reduce the cost of binder by 20–30¥/t.展开更多
采用低共熔溶剂为浸出剂,进行了含锌尘泥超声浸锌试验。分析了超声功率、温度、液固比、搅拌速率、反应时间等对锌浸出率的影响。结果表明:在超声功率90 W、温度40℃、液固比7 mL g、转速250 r min、浸出时间80 min条件下,锌超声浸出率...采用低共熔溶剂为浸出剂,进行了含锌尘泥超声浸锌试验。分析了超声功率、温度、液固比、搅拌速率、反应时间等对锌浸出率的影响。结果表明:在超声功率90 W、温度40℃、液固比7 mL g、转速250 r min、浸出时间80 min条件下,锌超声浸出率可达98.48%。超声强化浸出过程受混合固体产物层的控制,表观活化能为11.23 kJ mol。展开更多
基金the Fundamen-tal Research Funds for Central Universities(No.FRF-SD-12-013A)the State Key Laboratory of Advanced Metallurgy,China
文摘A one-dimensional unsteady mathematical model was established to describe direct reduction in a composite pellet made of metallurgical dust. The model considered heat transfer, mass transfer, and chemical reactions including iron oxide reductions, zinc oxide reduction and carbon gasification, and it was numerically solved by the tridiagonal matrix algorithm (TDMA). In order to verify the model, an experiment was performed, in which the profiles of temperature and zinc removal rate were measured during the reduction process. Results calculated by the mathematical model were in fairly good agreement with experimental data. Finally, the effects of furnace temperature, pellet size, and carbon content were investigated by model calculations. It is found that the pellet temperature curve can be divided into four parts according to heating rate. Also, the zinc removal rate increases with the increase of furnace temperature and the decrease of pellet size, and carbon content in the pellet has little influence on the zinc removal rate.
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financially supported by the Guizhou Prov-ince Nomarch Fund for Excellence Educationists, Scientists, and Technicians (No. 2005-363)the Natural Science Fund of Guizhou Provincial Education Department of China (No. 2007-078)
文摘A thermodynamic analysis on the acid leaching process of germanium oxide dust and discussion on the behaviors of main substances of the dust in the leaching process were carried out. The effects of temperature, acid concentration, leaching time and stirring speed on the leaching rate of germanium were investigated. Based on the characteristic of the dust, the kinetics and reactive mechanism of acid leaching were studied. The results show that the leaching of the dust by acid belonged to "the unreacted core shrinking model" of producing solid outgrowth layer. The chemical reaction was controlled by inner diffusion process. The apparent activation energy of leaching process was 12.60 kJ/mol. The leaching reaction of germanium was determined to be mainly second order reaction. The optimum conditions were the reaction temperature of 363 K, the leaching time of 2.5 h, the stirring speed of 120 r/min, the solid-to-liquid ratio of 1/8 and the acid concentration of 120 g/L. Under these conditions, the leaching rate of germanium can come up to more than 87%.
基金support from the Outstanding Youth Fund of Anhui Province(Grant No.2208085J19)the National Key Research and Development Program of China(Grant No.2022YFC3901405).
文摘The agglomeration of solid wastes is a key factor for subsequent utilization,while the difficulty in agglomeration and high cost have become common problems in the recycling process.The disk pelletizing process was adopted,based on the optimization method by liquid binder addition,and the influence mechanism of the ratio of typical solid wastes as blast furnace dust(BFD)and sludge generated by oxygen converter gas recovery(OGS)was explored.Meanwhile,the effect of binder solution concentration on the quality of green pellets was studied.Derived from the contact angle detection and infrared spectrum analysis,the liquid bridge model was established to study the bonding mechanism.The results showed that OGS had stronger adsorption effect with binder,and the hydrophilicity of BFD was better.When the concentration of binder was higher than 0.2 wt.%,the contact angle between the binder and BFD was bigger than that with OGS,while the capillary force between particles reduced with larger contact angle.The increment in the binder concentration increased the viscous force between particles and the maximum separation distance.The ultimate drop strength and compressive strength were related to the type of viscous force,and the compressive strength reflected the strength of the force between particles intuitively,while the drop strength represented the comprehensive forces of green pellets.Reasonable combination of BFD and OGS was available for pelletizing process,while the ratio of BFD should not exceed 32.0%,and binder C was added in the form of solution with the addition amount of 0.4 wt.%,which can reduce the cost of binder by 20–30¥/t.
文摘采用低共熔溶剂为浸出剂,进行了含锌尘泥超声浸锌试验。分析了超声功率、温度、液固比、搅拌速率、反应时间等对锌浸出率的影响。结果表明:在超声功率90 W、温度40℃、液固比7 mL g、转速250 r min、浸出时间80 min条件下,锌超声浸出率可达98.48%。超声强化浸出过程受混合固体产物层的控制,表观活化能为11.23 kJ mol。