Stockhouse efficiency: raw material drying, defrosting and preheating

Blast-furnace ironmaking capacity is usually located either close to mines or in areas where large quantities of steel are consumed. These locations are beneficial for logistics, but in some areas raw materials are exposed to substantial rainfall or snow during transportation and storage.

This introduces substantial amounts of moisture (and ice) into the blast furnace process, which results in higher production cost and process instability, also increasing CO₂ emissions. It is not uncommon for stockpiled coke to contain as much as 10-15% of moisture, while pellet moisture can reach 7-9%.

When charged to the blast furnace, wet or frozen materials require substantial additional heat in order to reduce risks related to water vapor condensation, reduced indirect reduction and scab formation. As such, managing these risks introduces a coke penalty, meaning adding coke as source of energy resulting in higher cost and emissions. Hence, the optimum solution is to eliminate the moisture before the raw materials enter the blast furnace in the first place.

Danieli Corus has developed a technology for de-freezing and drying raw materials by reducing the moisture of the charged raw materials in the stockhouse. This technology does not introduce any additional transfer steps, and associated coke degradation and additional dust formation from pellets are avoided.