Wet and preheated carbonization of a Spanish high volatile coal and blends with a Spanish prime coking coal

A Spanish high volatile coal (Modesta coal) and blends of this coal with 25, 50 and 75 wt.% of a Spanish prime coking coal (Figaredo coal) were coked at semi-industrial scale, either wet or by previous preheating. As the prime coking coal (Figaredo coal) is a dangerously swelling coal, the maximum amount to be added was established using the ASTM sole heated oven test. The high volatile coal increased coke strength considerably by preheating in comparison to wet charging. Blends adding 25 and 50 wt.% of Figaredo coal improved coke strength by preheating, although to a lower degree. However, as a result of the 75 wt.% addition of Figaredo coal, coke strength was impaired. Coke strength was measured by MICUM and IRSID tests and the cokes were also studied by image analysis, optical and scanning electron microscopy.