水热法脱除碳酸锂中微量硫杂质的研究

Study on removal of trace sulfur impurities from lithium carbonate by hydrothermal method

以工业级碳酸锂为原料,采用水热法脱除其中的微量硫杂质制备电池级碳酸锂,探究了水热温度、水热时间对硫杂质脱除效果的影响。利用扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)等方法对产物形貌和结构做了表征。研究结果表明,硫杂质主要以Li2SO4形式存在,吸附在碳酸锂表面;水热过程改善了碳酸锂的结晶性,减少了晶体表面活性位点,降低了表面硫杂质的吸附量。在温度为140℃、水热反应4 h后碳酸锂质量分数提高至99.8%,SO42-的质量分数降至6.30×10-4,均符合电池级碳酸锂行业标准(YST 582—2013)。

The battery-grade Li2CO3 was prepared with industrial-grade Li2CO3 as raw material,and trace sulfur impurities in the product was removed by hydrothermal method.The effects of hydrothermal temperature and hydrothermal time on the re moval of sulfur impurities were investigated.The morphology and structure of the product was characterized by means of scan ning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Results showed that the sulfur impurities mainly existed in the form of Li2SO4 and were adsorbed on the surface of lithium carbonate.The hydro thermal process improved the crystallization of lithium carbonate,reduced the active sites of crystal surface and reduced ad sorption of sulfur impurities on Li2CO3 surface.The purity of lithium carbonate increased up to 99.8%and SO42-mass fraction decreased to 6.30×10-4 after hydrothermal reaction at 140℃for 4 h,both meeting the battery-grade lithium carbonate indus try standard,YST 582—2013.