The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient ...The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.展开更多
Based on the new process named "Combination Method" for metallurgy and separation of Baotou mixed rare earth concentrate(BMREC),the aim of this paper is to clearly elucidate the phase change behavior of BMRE...Based on the new process named "Combination Method" for metallurgy and separation of Baotou mixed rare earth concentrate(BMREC),the aim of this paper is to clearly elucidate the phase change behavior of BMREC without additives during oxidative roasting at 450-800℃.The results indicate that the bastnaesite in BMREC is decomposed at 450-550℃,the weight loss is about 10.3 wt%,and the activation energy(E) is 144 kJ/mol.The bastnaesite in BMREC is decomposed into rare earth fluoride,rare earth oxides(La_(2)O_(3),Ce_(7)O_(12),Pr_(6)O_(11) and Nd_(2)O_(3)),and CO_(2),particularly,with the increase of roasting temperature,bastnaesite in BMREC is more completely decomposed into LaF_(3),which causes a decrease in leaching rate of La during the HCI leaching process.Additionally,the maximum cerium oxidation efficiency reaches about 60 wt% when the roasting temperature is equal to or above 500℃,and the oxidation reaction rate of cerium increases with the increasing roasting temperature.展开更多
基金financially supported by the National Natural Science Foundation of China (No.51964046)。
文摘The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.
基金Project supported by the National Key Research and Development Program of China(2020YFC1909104)Science and Technology Major Project of Guangxi(GuikeAA18242022)Hebei Province Key Research and Development Plan Project(20374104D)。
文摘Based on the new process named "Combination Method" for metallurgy and separation of Baotou mixed rare earth concentrate(BMREC),the aim of this paper is to clearly elucidate the phase change behavior of BMREC without additives during oxidative roasting at 450-800℃.The results indicate that the bastnaesite in BMREC is decomposed at 450-550℃,the weight loss is about 10.3 wt%,and the activation energy(E) is 144 kJ/mol.The bastnaesite in BMREC is decomposed into rare earth fluoride,rare earth oxides(La_(2)O_(3),Ce_(7)O_(12),Pr_(6)O_(11) and Nd_(2)O_(3)),and CO_(2),particularly,with the increase of roasting temperature,bastnaesite in BMREC is more completely decomposed into LaF_(3),which causes a decrease in leaching rate of La during the HCI leaching process.Additionally,the maximum cerium oxidation efficiency reaches about 60 wt% when the roasting temperature is equal to or above 500℃,and the oxidation reaction rate of cerium increases with the increasing roasting temperature.
