The shape factors of twelve calcined cokes of 50 × 70 mesh particle size were measured. The shape factors of the nine delayed petroleum cokes were all higher than those for the fluid coke, coal-tar pitch coke, and gilsonite coke. Heating a delayed petroleum coke between 1000 and 2750°C prior to grinding had a minor effect on the shape factor of the 40 × 70 mesh material. The relative crystallite orientation in the calcined cokes (as measured by four different X-ray diffraction criteria) varied markedly. Heat treatment up to 2750°C of a delayed petroleum coke produced a substantial increase in relative crystallite orientation, but the orientation fell far short of that found in Ceylon natural graphite. The relative grindability of the calcined cokes varied markedly, with the cokes of best crystallite alignment generally being the easiest to grind. On the other hand, the ease of grindability decreased sharply following heat treatment of a delayed petroleum coke between 1000 and 2000°C; the grindability was essentially constant for higher heat treatment temperatures.
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