Profitable Calcining of NonCalcinable Pet Coke RD .
In a "Shaft calciner" green coke is filled on top into individual shafts and flows by gravity through these shafts in 24 to 36 hours, resulting in a heat up rate of ~1°C per minute (compared to 50°C in a rotary kiln). Thanks to this very slow heatup rate, green coke with high VCM (12 – 16%) contents can be calcined.