石墨浮选精矿碱酸法制备高纯石墨

以固定碳含量92.49%的石墨浮选精矿为原料，采用改进碱酸法(增加了碱洗工序)纯化制备高纯石墨。分析了Si、Al、Fe等主要杂质元素的存在形态，考察了烧碱用量、焙烧温度/时间、水浸液固比/温度/时间以及酸浸硫酸浓度/温度/时间等因素对提纯效果的影响，研究了Si、Al、Fe等杂质在纯化过程中的行为走向。结果表明，石墨浮选精矿中的杂质主要为石英、绢云母等，采用改进碱酸法可以获得高纯石墨，产品固定碳含量可达到99.95%; 采用硫酸浸出可以很好地脱除Si、Al等杂质，而对Fe、Ca等金属离子杂质脱除效果不理想。纯化过程对石墨晶体结构和片状微观形貌均没有造成明显影响。

Preparation of High-Purity Graphite with Flotation Concentrate Using Improved Alkali-Acid Method

By using graphite flotation concentrate with a fixed carbon content of 92.49% as raw material, a kind of high-purity graphite was prepared with an improved alkali-acid method. The existing state of the main impurities, such as Si, Al and Fe, was analyzed, and the effects of caustic soda content, calcination temperature and time for Alkali roasting process, liquid-solid ratio, temperature and time for water leaching process, and sulfuric acid concentration, temperature and time for acid leaching, on the purification effect of graphite were investigated. The transformation behavior of impurities (Si、Al、Fe) in the purification process was also studied. The results show that the predominant impurities in graphite concentrate are quartz and sericite, and a high-purity graphite with the fixed carbon content of 99.95% can be prepared by using improved alkali-acid method. Sulfuric acid leaching can be adopted for the effective removal of impurities of Si and Al，but can't bring ideal effect to the removal of impurities of Fe and Ca. The purification process has no obvious effect on the crystal structure and flake morphology of graphite.