隐晶质石墨提纯工艺中硅的焙烧动力学研究

Baking Kinetics for Silicic Impurity in Purification Process of Aphanitic Graphite

研究了隐晶质石墨的提纯工艺中焙烧动力学方程。分析了焙烧时间、焙烧温度及矿样原始尺寸对焙烧过程中脱硅效果的影响。研究结果表明:硅是最难脱除的杂质,其主要赋存物相为高岭石、石英和云母;采用碱焙烧法以及氢氟酸法相结合的工艺可以使脱硅率达到80%以上;采用酸浸加压等强化措施后,最终得到的石墨纯度可达99.56%;碱焙烧过程的活化能为40.694 kJ/mol;降低了原矿平均粒度,提高了焙烧温度;添加矿化剂有助于提高脱硅效率。

Kinetic equation in the baking process of purifying aphanitic graphite were researched. Influence of the diameter of raw ore, alkali baking time and baking temperature on desilication was discussed. Phase analysis results show that it is difficult to eliminate silicic impurity. Kao-line, silicon dioxide and mica are the most familiar silicic impurity in the raw ore. A high silicic transform rate over 80% can be obtained by a special technology combining alkali leaching and hydrofluoric acid soaking. The purity of the graphite reaches 99.56% by high-pressure acid leaching method. Kinetic results show that the activation energy is 40.964 kJ/mol in the alkali leaching process. Reducing average grain size of raw ore, prolonging aikali baking time and adding-mineralizer are all helpful to increasing the silicic transform rate.