二氧化碳中和钨酸铵溶液制备细颗粒仲钨酸铵

Preparation of fine ammonium paratungstate by neutralizing ammonium tungstate solution with carbon dioxide

采用二氧化碳中和钨酸铵溶液结晶制备细颗粒仲钨酸铵(APT),考察时间、温度、二氧化碳流量、钨酸铵溶液中三氧化钨质量浓度、氯化铵质量浓度和转速等因素对APT结晶的影响。研究结果表明:在一定范围内,增大二氧化碳流量、提高氯离子质量浓度和三氧化钨质量浓度有利于制备细颗粒APT;转速对APT粒度影响较小;延长结晶时间和提高反应温度,APT粒度会变大,不利于制备细颗粒APT。当反应时间为20 min、温度为90℃、二氧化碳流量为5 L/min、钨酸铵溶液中三氧化钨质量浓度为200 g/L、氯化铵质量浓度为62 g/L、转速为200 r/min时,该工艺制备的APT费氏(Fsss)粒度为15.5μm、粒度分布窄,其D(90)-D(10)/2D(50)为0.66且形貌完整。与工业上蒸发结晶工艺制备的APT相比,本工艺制备的APT粒度更小且粒度分布更窄,是制备超细钨粉和超细碳化钨粉的良好原料。

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 15.5μm,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.