半焦的挥发分较低，燃烧过程中存在难燃、NO_x产量高的缺点。在入炉燃烧前对其进行超细粉碎有效的改进方法。为研究低阶煤及其半焦的超细粉碎特性，利用管式炉制备神华烟煤、锡盟褐煤的干燥样品和700 ℃条件下的热解半焦。通过扫描电镜和X射线衍射仪进行微观理化特性表征，使用哈氏可磨仪和振动磨分别进行输入有限和过量能量条件下的破碎实验，采用激光粒度仪分析粒度分布规律，并结合分形理论研究破碎机理。微观理化分析显示，神华烟煤在热解过程中会出现热塑性阶段，产生了气泡状孔隙，锡盟褐煤的孔隙主要受脱水影响，无此阶段。相较于原煤，2种半焦均有芳香结构增长，炭化程度增大。破碎实验显示，在输入有限破碎能量时，相比于原煤，神华干燥样品的可磨变化不大，其半焦样品的可磨性则更差；锡盟褐煤的干燥样品和半焦的可磨性均要远好于其原煤。输入过量能量时，2种半焦的破碎效果均比原煤好。粒度的分形分析表明，相比于原煤，2种半焦的体积破碎所能延伸到的粒度范围更小。造成粉碎特性差异的原因为，破碎初期，发达且不规则的孔隙结构有利于节约输入的能量，提高破碎效能，也因此褐煤强烈的脱水过程可以有效提高其可磨性；破碎后期，在输入能量足够的情况下，由于热解半焦内部的微晶尺寸变大，且发生了不均匀的压实，引起内部应力升高，产生了更多的微小裂隙，最终使半焦宏观上显示出更多的脆性，使其容易发生整体性的体积破碎。

Semi-coke has a low volatile content,so it is difficult to ignite and would produce large amount of NOx during combustion process.An effective improvement method is to super finely pulverized it before burning in the furnace.In order to study the superfine comminution characteristics of low rank coal and its semi coke,Shenhua bituminous coal and Ximeng lignite were selected and their dehydrated samples and 700 ℃ semi-cokes were prepared by tube furnace.The samples were characterized by scanning electron microscope and X-ray diffraction instruments and the comminution experiments with different input energy level were carried out by Hardgrove apparatus and vibration mill.The comminution mechanism was analyzed by laser particle size analyzer combined with fractal theory.Micro-physical and chemical analysis shows that during the pyrolysis process of Shenhua bituminous coal,there was a thermoplastic stage,which produces bubble-like pores.The pores of Ximeng lignite are mainly affected by dehydration process and there was no such stage.Compared with raw coal,both types of semi-coke have increased aromatic structure and increased degree of carbonization.When limited comminution energy is input,compared with raw coal,the grindability of Shenhua dehydrated sample has little change,while the grindability of semi-coke sample is worse;The grindability of both Ximeng dehydrated sample and its semi-coke are much better than that of raw coal.When excessive energy is input,the comminution effect of the two types of semi-coke is better than that of raw coal.The fractal analysis of particle size shows that compared with raw coal,the size range of semi coke is smaller.The results show that the developed and irregular pore structure is conducive to saving the input energy and improving the comminution efficiency in the early stage of comminution;With the increase of temperature,the microcrystalline size in the semi coke becomes larger,and uneven compaction occurs,causing internal stress,more micro cracks are produced.In the late stage of crushing,when the input energy is excessive,the above changes make the semi coke show more brittleness on the macro level,and makes overall shattering easy to happen.

1 实验部分

   1.1 实验材料

   1.2 实验方法

2 实验结果及分析

   2.1 扫描电镜形貌分析

   2.2 碳微晶结构分析

   2.3 输入有限能量条件下的破碎特性

   2.4 输入过量能量条件下的破碎特性

   2.5 粒度分布的多段分形分析

3 结论