Effects of coal interactions during cokemaking on coke properties under simulated blast furnace conditions

Abstract

The cokes produced from single coals and blends of these coals were investigated under the simulated blast furnace (BF) conditions. Comparison of the weighted average values of single coal cokes and the measured values of cokes from blends revealed the coal interactions during carbonisation and the effects of these interactions on coke properties under the simulated BF conditions. Blending coals together resulted in a significant fluidity reduction from the expected values. The large amount of volatile matter released from the low rank coal provided better conditions of crystallites growth for other coal components in the blends, thereby resulting in the pervasively higher measured graphitization degree. Raman spectroscopy analysis indicated that the higher measured graphitization degree was mainly contributed by the lenticular and ribbon microtextures. Although the caking properties of the blends were remarkably reduced from the expected values, the measured microstrength did not have a significant difference from the calculated values. However, the measured macrostrength were higher than the calculated values. The differences in the softening and resolidification temperatures of coals restricted the dilatation but promoted the contraction of the blends, which resulted in a reduced porosity development from the expected value, thereby improving the strength of the produced cokes.