Effect of the grinding behaviour of coal blends on coal utilisation for combustion

Grinding of a high volatile bituminous coal was performed in three comminut ion devices: Raymond Mill (RM), Rolls Crusher (RC) and Ball Mill (BM). The pulverised samples were sieved to obtain four particle size fractions, and temperature-programmed combustion (TPC) was used for the evaluation of thei r combustion behaviour. In addition, three coals of different hardness and rank were mixed in various proportions in order to compare the combustibili ty characteristics of the binary coal blends with those of the individual c oals. The effect of coal blending on grindability was also studied. It was found that grindability was non-additive especially when coals of very diff erent Hardgrove Grindability Index (HGI) were blended. The combustion studi es also suggested that there exists an interaction between individual coals when they are burnt as a blend.