Densification of raw coke powder compacts

Abstract

The effects of grinding on densification of a petroleum raw coke were examined. The compact of the powder ground for a short time showed large puffing during calcination below 400 °C, and no densification by subsequent heat treatment. It was found that the puffing could be suppressed by long grinding of the powder. In the compact of the powder subjected to prolonged grinding, the pore volume decreased in two temperature ranges of calcination, at 400–500 and 600–700 °C. The first decrease seems to be attributed to softening and volume reduction due to carbonization of quinoline-soluble components among the coke grains. The second decrease suggests that the sintering due to solid state material transport, such as viscous flow and plastic deformation, takes place in addition to gas-phase material transport. The increase in bulk density at temperatures over 1000 °C was mainly due to contraction of constituent grains in which micropores decreased, not a decrease in pore volume of the compact. The most remarkable effect of grinding on densification of the raw coke was the suppression of puffing during the calcination process.