To reduce the energy cost during pulverizing process of lignite,the previous researches were summarized.It pointed out that several factors could influence the grindability of the lignite,such as the moisture content,petrographic composition and geographical conditions.The moisture content is considered as the major reason for poor grandability of the lignite,the higher the moisture content,the poorer the lignite's grindability.So the most effective method to improve the lignite's grindabilty is drying it.However,during the drying process,the pore structure and specific surface area of the lignite will change.The cracks created by moisture precipitation are most likely the main reason in explaining the increasing of the coal grindability as a result of the drying process.On this basis,the grindability of microwaving exposed coals and conventionally heating coals were compared.The results show the microwave heating has the advantages of fast drying rate,short drying time and high energy utilization efficiency.Finally,the evaluation indexes of coal grinding were discussed and the shortage of HGI was figured out.Some new evaluation indexes based on fractal theory and others were also introduced.%为降低褐煤在磨矿过程中的能耗,通过综述前人的成果,指出影响褐煤可磨性的主要因素有煤样的水分含量、岩相成分及成煤条件等.其中褐煤可磨性差的主要原因是水分含量高,煤样的水分含量越高,煤的可磨性越低,增加褐煤可磨性最简单的手段就是对其进行干燥脱水.褐煤干燥过程中煤孔隙结构和比表面积会发生变化.水分析出产生裂隙是褐煤可磨性增大的机理.在此基础上比较了采用普通的外热源干燥法和微波干燥法在增加褐煤可磨性方面的情况.微波干燥技术具有干燥速率快、干燥时间短、能量利用效率高等优点.最后对煤可磨性的评价指标进行了讨论,指出了哈式可磨性指数的局限性,介绍了基于分形等理论的新的可磨性评价指标.
展开▼
