Modern applications of the blast furnace

Iron blast furnaces

Blast furnaces are still an important part of modern ironmaking production.Modern furnaces are very effaicient, including Cowper furnaces for preheating the blast and employing recovery systems to extract heat from the hot gases exiting the furnace.Industry competition drives higher productivity.The world's largest blast furnace is in South Korea, with a capacity of about 6,000 cubic meters (210,000 cubic feet).It can produce about 5,650,000 tons (5,560,000 metric tons) of iron per year.This is a significant increase from the typical 18th century furnace, which averaged around 360 tons (350 long tons; 400 short tons) per year. Variants of the blast furnace, such as the Swedish electric blast furnace, were developed in countries without indigenous coal resources.According to the Global Energy Monitor,blast furnaces may become obsolete in order to meet climate change targets for reducing CO2 emissions, but BHP Billiton disagrees. Alternative processes involving direct reduction of iron may be successful but this also requires the use of blast furnaces to melt the iron and remove gangue (impurities), unless the ore is of very high quality.

Oxygen blast furnace 

The Oxygen Blast Furnace (OBF) process has been studied extensively theoretically due to its potential to save energy and reduce CO2 emissions.This type is probably most suitable for use with CCS.The main blast furnace is divided into three reduction zones (523-973k), slagging zone (1073-1273k), and combustion zone (1773-1873k).Blast furnaces are rarely used today for copper smelting, but modern lead smelting blast furnaces are much shorter and rectangular in shape than iron blast furnaces.The walls of modern lead blast furnaces are water-cooled steel or copper jackets, and the side walls are not refractory lined.The bottom of the furnace is the hearth of refractory material (brick or castable refractory).Lead blast furnaces are usually open-topped instead of charging hoods as in iron blast furnaces.The blast furnace used at the Nyrstar Port Pirie lead smelter differs from most other lead blast furnaces in that it has double tuyeres rather than the single tuyeres normally used.The lower shaft of the stove is chair-shaped, and the lower part of the shaft is narrower than the upper part.The lower vents are located in the narrow section of the shaft. [76] This allows the upper part of the shaft to be wider than the standard.

Zinc blast furnaces

The blast furnaces used in the Imperial Smelting Process ("ISP") were developed from standard lead blast furnaces, but were completely sealed.This is because the zinc produced by these furnaces is recovered as metal from the gas phase, and the presence of oxygen in the offgas leads to the formation of zinc oxide.The blast furnaces used in ISP are operated at a higher intensity than standard lead blast furnaces, with higher blast rates per square meter of hearth area and higher coke consumption.Producing zinc using ISP is more expensive than using electrolytic zinc plants, so several smelters using this technology have closed in recent years.

However, ISP furnaces have the advantage of being able to process zinc concentrates with higher lead content than electrolytic zinc plants.

Manufacture of stone wool

Rock wool or rock wool is a textile mineral fiber used in insulation products and hydroponics.It is manufactured in a blast furnace from diabase, which is very low in metal oxides.The resulting slag is extracted and spun into rock wool products also produces very small amounts of metal, which is an unwanted by-product.