Preparation of fine ammonium paratungstate by neutralizing ammonium tungstate solution with carbon dioxide
Fine particle ammonium paratungstate was prepared by neutralizing ammonium tungstate solution with carbon dioxide.There were some factors that were investigated including time,temperature,carbon dioxide flow,tungsten trioxide mass fraction,ammonium chloride mass fraction and agitator speed on APT crystallization.The results show that within a certain range,increasing the carbon dioxide flow,chloride ion and tungsten trioxide mass fraction is conducive to the preparation of fine particle APT.The agitator speed has a little effect on the APT particle size.Prolonging the crystallization time and increasing the reaction temperature well cause the APT particle size to become coarse,which is not conducive to the preparation of fine particle APT.When reaction time is 20 min,temperature is at 90℃,carbon dioxide flowed rate is 5 L/min,tungsten trioxide mass fraction in ammonium tungstate solution is 200 g/L,ammonium chloride mass fraction of 62 g/L,agitator speed is at 200 r/min,the Fsss size of APT prepared by this process is 15.5 μm,the particle size distribution is narrow,the D(90)-D(10)/2D(50)is 0.66 and the morphology is complete.Compared with the APT prepared by evaporation crystallization in industry,the APT prepared by this process has a finer particle size and narrow particle size distribution,which is a good raw material for the preparation of ultrafine tungsten powder and ultrafine tungsten carbide powder.
fine particle ammonium paratungstatecarbon dioxidegranularityammonium tungstate solutioncrystallization
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维普
