PREHEATING TECHNIQUES TO MANUFACTURE METALLURGICAL COKE

Recently, reserves of good coking coals have become less available and comparatively more expensive. Resources are being extended by the use of coal blends with different coking properties and/or selective additives. Coal preheating technology emerged as a technique to overcome some of these problems. It has several advantages including: increases in coke oven productivity, improvements in quality of metallurgical coke, greater uniformity of charge, less air pollution by using a closed charging system, levelling of the charge, a saving in energy because dry coal is more efficient in the preheater than in a coke oven, and the possibility of using poorer and cheaper coking coals. The disadvantages of this technique are the handling of fine and hot coal, the carry-over and the preheater fines. Currently, the preheating process is being re-considered in combination with dry-cooling of coke in a European Research Project called "Jumbo Coking Reactor", which is based on past and current experience of development of modern cokemaking technology. This study reviews preheating technology as a means to widen the range of coking coals including not only the high-volatile coals which are more abundant, but also semi-anthracite and petroleum coke. A 6 t Experimental Coke Oven and a 2 t/h Preheating Pilot Plant (Precarbon Process) were used.