The Blast Furncace is the most common way to obtain HSLA Steel Ingots. The furnace requires very little resources and is needed for most other machines to be made, and so it should be your first RotaryCraft block made.
The Blast furnace requires coal and gunpowder to function, note however that the coal and gunpowder is a component of the recipe and is not the energy source. Note: In newer versions, There is a third slot above the coal slot for sand. This is not a requirement in older versions but is necessary in newer ones.
The Blast furnace will require an external source of heat to function, the most common way to do this is simply place a block of lava beside or below your furnace.Lava will heat the furnace to a maximum of 640C. The number of lava blocks does not influence the maximum heat, additional lava source blocks do not influence the speed that maximum heat is achieved.
Higher heats can be achieved by using the Heater, or the Friction Heater. This will increase the speed of the smelting.
Colder biomes, such as Taiga influence the maximum heat. Using just lava 580C is the maximum heat in these biomes. (As the blast furnace only works above 600c, they will not work in a Tiaga with only lava.) Hotter biomes have no effect however.