Coal Coke is a fuel element just like normal Coal, but it burns twice as long. Coal Coke is made by putting normal Coal into a Coke Oven, or it can be found in dungeon Chests.
Coal Coke can't be used again in the Coke Oven, nor can it be macerated using a Macerator.
Coal Coke is one of only two fuels that can be used in a Blast Furnace, a stack of 64 Coal Coke is enough to smelt 32 Iron Ingots into Steel Ingots.
Making Coal Coke in Tekkit 3.1.2
Making Coal Coke in Tekkit 3.1.3