In order to solve the problems of environment pollution and high cost in traditional process of bismuth subcarbonate preparation, a new process using ball-milling transformation method from NH4HCO3 and Bi2O3 was proposed. Additionally, the kinetics of bismuth subcarbonate preparation was studied. Effects of reaction temperature, particle size of bismuth oxide, solid-to-liquid ratio and concentrations of ammonium bicarbonate on the conversion rate of bismuth oxide were studied. The results indicate that the conversion rate of bismuth oxide significantly increased under the conditions of higher temperature, smaller particle size, higher concentration of ammonium bicarbonate and smaller solid-to-liquid ratio. The XRD and ICP-AES analyses show that the purity of product is high. The reaction kinetics with activation energy of 9.783 kJ/mol was analyzed by shrinking core model, and the whole transformation process is controlled by solid product layer diffusion. A semi-empirical kinetics equation was obtained to describe the conversion process.
针对传统次硝酸铋制备过程中产生污染环境的有毒气体二氧化氮及大量氨氮废水等问题,提出采用液相球磨转化法制备次硝酸铋新工艺,运用正交试验和单因素试验方法对氧化铋球磨转化制备次硝酸铋工艺进行研究。研究结果表明:各因素对转化率影响性由大至小的顺序为液固比、球料比、硝酸浓度、反应时间;氧化铋球磨转化制备次硝酸铋的最佳工艺条件如下:硝酸浓度为0.5 mol/L,液固比为15:1 m L/g,球料比为10:1(质量比),反应时间为1 h,在此最佳工艺条件下,氧化铋的平均转化率为90.71%。制备的次硝酸铋主要呈棒状形态分布。
