碱酸法制备高纯石墨试验研究

以黑龙江某地细鳞片石墨浮选精矿为原料进行碱酸法提纯试验，探讨了碱酸法提纯的最佳工艺条件。研究表明:在NaOH用量3.0 g（碱固比0.6:1）、焙烧温度750℃、焙烧时间40 min、浸出水用量50 mL、酸浸HCl浓度1.0 mol/L、用量40 mL、酸浸时间40 min的条件下，通过碱熔焙烧-水浸出-酸浸的工艺可将石墨固定碳含量由95.89%提升至99.94%。随着反应的进行以及物相的变化，杂质最终演变成可溶性物质，以洗涤的方式被去除；水浸出过程中保持弱碱性环境，有利于硅酸钠的溶解。 

Experimental Study on the Preparation of High Purity Graphite by Alkali-acid Method

Experiments were carried out on a fine flaky graphite flotation concentrate in Heilongjiang Provence by alkali-acid purification method. The optimum technological parameters were investigated. The results showed that under the conditions of NaOH dosage 3.0 g (ratio of alkali to solid 0.6:1), roasting temperature 750℃, roasting time 40 min, leaching water dosage 50 mL, acid leaching HCl concentration 1.0 mol/L, dosage 40 mL and acid leaching time 40 min, the fixed carbon content in graphite was increased from 95.89% to 99.94% by the process of alkali fusion roasting-water leaching-acid leaching. As the reaction proceeds and the phase changes, the impurities are eventually transformed into soluble matters and are washed with pure water. Maintaining a weak alkaline environment during water leaching is beneficial to the dissolution of sodium silicate.