This blueprint is part of the "Dense City Blocks" blueprint book. (HQ Album, Complete Book String).
Smelts 8.5 Express Belts of iron ore into six express belts of iron plate and one express belt of steel.
Belts 1-5 are used exclusively for iron; saturating them suffices for 6 iron outputs. Belt 6 used for steel, but runoff is used to saturate the leftmost ore belt (to conserve UPS). Belts 7-9 are used excluively for steel.