兰炭和喷吹煤组成与结构特征对可磨性的影响

 低变质煤低温热解产物兰炭(半焦)用于高炉喷吹,可降低焦比,节约炼铁成本;但多数兰炭可磨性差,限制了其使用。以神木两种典型兰炭和两种喷吹煤为研究对象,分析比较了其破碎特征,采用XRF和XRD检测了兰炭和喷吹煤灰分中物相组成,采用SEM和氮气吸附法研究了兰炭和喷吹煤的破碎形貌和微观结构。结果表明,喷吹煤的可磨性高于兰炭,烟煤可磨性最优;钙、硅含量与可磨性之间存在协同和抑制作用,即钙含量越多,可磨性越高,且钙元素主要以CaO形式存在,硅的作用则相反;喷吹煤表面致密平整,而兰炭表面孔隙结构发达。在球磨过程中,喷吹煤以体积粉碎为主,而兰炭则以表面粉碎为主,粉碎方式不同是两者可磨性差异大的主要原因。

Effect of composition and structural characteristics of char and injected coal on grindability

The char (semi coke), a product of low-temperature pyrolysis of low metamorphic coal, can be used for blast furnace injection, which can reduce the coke ratio and save the cost of ironmaking. However, most of char is hard to grind, which limits its use. Two kinds of char in Shenmu and two kinds of injected coal are taken as the research objects, and their crushing characteristics are analyzed and compared. The phase composition of char and injected coal ash is detected by XRF and XRD, and the crushing morphology and microstructure of char and injected coal are studied by SEM and nitrogen adsorption. The results show that the grindability of coal is better than that of char, and the grindability of bituminous coal is the best; there is a synergy and inhibition relation between Ca、Si content and grindability: that is the more Ca content, the better the grindability, the Ca elements mainly exist in the form of CaO, and the effect of Si is opposite; the surface of coal is dense and flat, and the pore structure of the surface of char is developed. In the ball milling process, the coal is mainly broken by volume, while the char is mainly broken by surface. The main reason for the big difference in grindability is the different ways of breaking.