Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In ...Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In this study,the effect of the silica saturation coefficient(x)on the carbonation of hydrogarnet was investigated from the kinetic perspective.The results indicated that the carbonation of hydrogarnets with different x values(x=0.27,0.36,0.70,and 0.73)underwent two stages with significantly different rates,and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3.The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol,respectively.Moreover,the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.展开更多
Ultrafine rare-earth oxides(REOs) are widely applied in all fields of daily life,but the conventional preparation methods are limited by a long procedure,low efficiency and severe environmental pollution.Our team has ...Ultrafine rare-earth oxides(REOs) are widely applied in all fields of daily life,but the conventional preparation methods are limited by a long procedure,low efficiency and severe environmental pollution.Our team has independently developed a jet pyrolysis reactor for the preparation of ultrafine cerium oxides,and this process has theoretical significance and practical application values.In this study,gas-solid pyrolysis reactions inside the jet-flow pyrolysis reactor were numerically simulated.We performed a coupling computation of the combustion,phase transformation and gas-solid reaction on Fluent and userdefined functions.We characterized the flows of different phases as well as the compositions and distributive laws of the reactants/products in the reactor.The gas-phase inlet velocity and dynamic pressure/additional pressure were related by a quadratic function.The velocity at the throat inlet changed the most,and the outlet velocity was very stable.The CeO2 concentrations were obviously stratified.This study enriches theories of jet-flow pyrolysis and theoretically underlies the optimization and popularization of self-developed pyrolysis reactors.展开更多
基金the National Natural Science Foundation of China(Nos.51874078,U1710257,U1202274,and 51764039)the Open Fund of Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education)Northeastern University,China(No.NEMM2019004).
文摘Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In this study,the effect of the silica saturation coefficient(x)on the carbonation of hydrogarnet was investigated from the kinetic perspective.The results indicated that the carbonation of hydrogarnets with different x values(x=0.27,0.36,0.70,and 0.73)underwent two stages with significantly different rates,and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3.The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol,respectively.Moreover,the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.
基金financially supported by the National Natural Science Foundation of China (No.51904069)the Natural Science Foundation of Hebei Province of China (No.E2019501085)+2 种基金the Colleges and Universities in Hebei Province Science and Technology Research Youth Fund (No.QN2019312)the Fundamental Research Funds for the Central Universities (No.N172303012)the National Science and Technology Support Program (No.2012BAE01B02)
文摘Ultrafine rare-earth oxides(REOs) are widely applied in all fields of daily life,but the conventional preparation methods are limited by a long procedure,low efficiency and severe environmental pollution.Our team has independently developed a jet pyrolysis reactor for the preparation of ultrafine cerium oxides,and this process has theoretical significance and practical application values.In this study,gas-solid pyrolysis reactions inside the jet-flow pyrolysis reactor were numerically simulated.We performed a coupling computation of the combustion,phase transformation and gas-solid reaction on Fluent and userdefined functions.We characterized the flows of different phases as well as the compositions and distributive laws of the reactants/products in the reactor.The gas-phase inlet velocity and dynamic pressure/additional pressure were related by a quadratic function.The velocity at the throat inlet changed the most,and the outlet velocity was very stable.The CeO2 concentrations were obviously stratified.This study enriches theories of jet-flow pyrolysis and theoretically underlies the optimization and popularization of self-developed pyrolysis reactors.
