| As a non-renewable strategic resource,rare earth has broad application prospects and is an important component of materials science.Rare earth compounds are an important part of the development and use of rare earths,and low-cost,green and environmentally friendly synthesis is the future development direction of rare earth compounds.Neodymium hydroxide?Nd?OH?3?as a chemical agent,the synthetic material is a rare earth,the catalyst material synthesis,neodymium salt intermediate,synthetic material or the like,can be applied to various synthesis field of rare earth materials.Therefore,that green synthesis method as well as process of Nd?OH?3 have became the focus of study.Under the premise of satisfying the physical properties and high-purity of Nd?OH?3 powder,the Nd?OH?3 with no emission,low energy consumption and short process is studied.so that the entire preparation process is more economical and environmentally friendly.At the moment,there are various methods and processes for making Nd?OH?3.but most of them have complicated preparation processes,high impurities content with product,high energy consumption in the preparation process,and insufficient shortage of waste liquid which is difficult to handle at the same time,resulting in resource waste and environmental pollution.In order to solve these shortcomings and issues of the existing Nd?OH?3 powder preparation processes,this paper studied the reaction under normal temperature and pressure based on the preparation of Nd?OH?3 by direct reaction of cerium oxide?Nd2O3?with water.The mechanism and process conditions of directly preparing high-purity Nd?OH?3 were proposed,and a new preparation craft for directly preparing high-purity Nd?OH?3 was proposed.The preparation process of Nd?OH?3 is simplified,efficient and cleaned in accordance with national energy conservation and emission reduction policies,and can meet the requirements of different users for Nd?OH?3.This topic is based on China's existing extraction and purification technology of rare earth,using high-purity Nd2O3 powder and deionized water?H2O?as raw materials to study the process parameters of Nd?OH?3 powder directly prepared by Nd2O3 hydration.In view of these shortcomings,the preparation technology and product quality of Nd?OH?3 powder were researched from the perspectives of energy saving and environmental protection.The effects about H2O/Nd2O3 molar ratio,stirring speed,feed water rate and stirring mode on Nd2O3 conversion and product morphology during hydration were studied by orthogonal test and single factor experiment.The thermodynamic and kinetic properties of the direct chemical combination of Nd2O3 and H2O were researched.The conversion rate of Nd2O3and the morphology,structure and purity of Nd2O3 were analyzed by chemical analysis,quality score calculation,scanning electron microscopy analysis,XRD analysis and particle size analysis.The particle size and distribution were studied.The experimental results show that the order of influence of hydration parameters on the process in this research system is the molar ratio of H2O/Nd2O3,stirring speed,stirring mode and water supply rate.The optimum molar ratio of H2O/Nd2O3 ranges from 5.6 to 6.3,the stirring speed is from 300 to 350 r/min,and the feed water rate is 1 mL/min.The single factor experiment determined the process parameters:the optimum molar ratio of H2O/Nd2O3 was 5.6,the stirring speed was 350r/min,the feed water rate was 1mL/min,then the reaction was carried out by continuous stirring.The thermodynamic calculation results show that it is an exothermic reaction,and the exotherm heat Q=164.13 kJ/mol.The mechanism of Nd2O3 hydration process and reaction process were determined by studying the kinetics of Nd2O3 hydration reaction.The activation energy of this reaction is154.56kJ/mol.By the improving,perfecting and increasing of the existing Nd2O3 hydration process,the high-purity Nd2O3 powder is directly converted into high-purity Nd?OH?3 powder in one step,and the reaction process does not require heating,and no waste liquid is produced.Subsequent reprocessing of the product is not required.In this study,Nd?OH?3 powder was prepared under the conditions of no emission,lower energy consumption,lower cost,continuous and clean.The research and application of the direct reaction of Nd2O3 with H2O to prepare Nd?OH?3 powder,This method enables efficient use of rare earth resources,combines production process with economic benefits and environmental conservation,and realize the preparation of Nd?OH?3 powder green pollution-free.The research of this subject has important theoretical value and practical value,and can be applied to the production process of other series of rare earth hydroxides. |
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