Maximum Blast Furnace Temperatures

Temperatures in a blast furnace can reach levels needed to extract metals from ore.

Blast furnaces serve an important role in industrial production and are typically used to smelt metals, particularly iron. The temperature in a blast furnace needs to be consistently hot and at temperatures that will melt the metal. The maximum blast furnace temperature will depend upon various factors, such as the furnace size and type.

Maximum Temperatures

The maximum temperature of a blast furnace can exceed 2,000 degrees Fahrenheit, according to Gregory C. Walsh, author of "Cost Effective Blast Furnace Stove Control." The actual maximum temperature of a furnace can vary, depending largely upon the type of metallurgical purpose it serves. The actual melting point of iron is somewhere around 1,500 degrees, but furnaces can burn much hotter to ensure that the melting process has fully occurred.

Smelting

Smelting is the process of extracting metal from ore. The smelting process only occurs at extremely high temperatures over 1,500 degrees. At this temperature or higher, iron ore begins to melt into a molten state where it then runs or trickles down inside the furnace. As this occurs, the molten metal can be extracted from the furnace at regular intervals. The entire process generally takes about six to eight hours for each load of iron ore.

Coke

The production of coke, the low-sulfur bituminous coal used to make fuel, also depends upon the continuous high temperatures produced by a blast furnace. Coke production occurs at about 1,100 degrees Fahrenheit, according to the American Iron and Steel Institute. This coal is sometimes used as a reducing agent in iron ore production as well. Coke production occurs in several phases but reaches its final stage near this 1,100-degree mark.

Operation

Blast furnaces work by blowing hot air into the bottom of a chamber where coal and other items are heated. This air goes through several chemical reactions in a short period of time, and the entire process of heating the furnace takes about six to eight seconds. As the hot air strikes the intended substance it will heat, the substance begins to break down and trickle to the bottom. A typical blast furnace will run continuously for about 10 years with only periodic stoppage for maintenance purposes.

References

• American Iron And Steel Institute: Coke Production for Blast Furnace Iron Making
• Hypertextbook: Temperature of a Blast Furnace
• Nedians Engineering Fundamentals: The Electric Arc Furnace