钛石膏中铁浸出动力学及其酸浸循环工艺研究

Study on kinetic of iron leaching from titanium gypsum and its cyclic acid leaching process

硫酸法制备钛白粉的过程中产生了钛白废酸及钛石膏,采用以废治废思路,将钛白废酸作为浸取剂循环浸出钛石膏中的铁杂质,以实现资源的有效利用。研究了钛白废酸循环酸浸钛石膏的最优工艺条件,实验结果表明,在反应温度为333.15 K、液固质量比(以下简称液固比)为5∶1、反应时间为60 min、循环酸浸2次的条件下,钛石膏的除铁效率能达到80%以上。结合SEM、XRF、XRD等表征结果对比分析酸浸前后的钛石膏产品,结果发现酸浸条件能降低钛石膏中多种杂质组分含量,且酸浸前后钛石膏的物相组成均为CaSO_(4)·2H_(2)O。在上述研究的基础上形成了完整的钛石膏处理工艺,研究了在钛白废酸体系下,钛石膏中铁元素的浸出特性,并使用浸出动力学模型进行了拟合与计算,结果表明,该浸出过程受内部扩散控制,反应的表观活化能为59.08 kJ/mol。

During the process of preparing titanium dioxide powder using sulfuric acid method,titanium dioxide waste acid and titanium gypsum are generated.A waste treatment approach is adopted,using titanium dioxide waste acid as a leaching agent to recycle and leach iron impurities from titanium gypsum,in order to achieve effective utilization of resources.The op⁃timum process conditions for the cyclic acid leaching of titanium gypsum with titanium white waste acid were investigated.The experimental results showed that the iron removal efficiency of titanium gypsum could reach more than 80%at reaction temperature of 333.15 K,liquid⁃to⁃solid mass ratio of 5∶1,reaction time of 60 min and two times of cyclic acid leaching.The titanium gypsum products before and after acid leaching were compared and analyzed based on SEM,XRF,XRD and other characterization results.The results showed that the acid leaching conditions could reduce the content of various impu⁃rity components in titanium gypsum,and the composition of the physical phase of titanium gypsum before and after acid leaching was CaSO_(4)·2H_(2)O.On the basis of the above research,the complete titanium gypsum treatment process was formed.The leaching characteristics of elemental iron in titanium gypsum under the titanium dioxide waste acid system were investi⁃gated,and fitted and calculated using a leaching kinetic model.The results showed that the leaching process was controlled by internal diffusion and the apparent activation energy of the reaction was 59.08 kJ/mol.