Study on Morphology of Submicron Ammonium Perrhenate Prepared by Vacuum Spray Freeze Drying and Its Reduced Rhenium Powder AITranslate

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Chinese Library Classification Number:TQ137.1[化学工程—无机化工];TB383[一般工业技术—材料科学与工程]

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Submicron ammonium perrhenate was prepared via vacuum spray freeze drying.The effects of ammonium perrhenate solution concentration,feed pump flow rate and initial drying chamber temperature during vacuum spray freeze drying on the particle size and morphology of ammonium perrhenate and its re-duced rhenium powder were investigated by single-factor experiments and orthogonal experiments.The re-sults of single-factor experiments indicate that the atomizer is blocked due to the crystallization of super-saturated ammonium perrhenate at low temperature when the mass concentration of ammonium perrhenate exceeds 20 g/L.Submicron ammonium perrhenate particles with an average size of<1μm can be obtained only at a concentration of 20 g/L,and the corresponding reduced rhenium powder exhibits good morpho-logical heritability.Orthogonal experimental results show that feed pump flow rate is the key factor(range 78.34%)controlling the proportion of acicular morphology of ammonium perrhenate.The combination of low flow rate(e.g.,5 mL/min),medium-low temperature(e.g.,-50℃)and low concentration(e.g.,10 g/L)can significantly increase the acicular morphology proportion(up to 100%).This study reveals the regulation mechanism of droplet dispersion-crystallization kinetics on grain morphology,providing a basis for process parameter selection in the controllable synthesis of rhenium-based materials.