Pulverized coal injection is a method for improving the performance of a

blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being supplied above atmospheric pressure. In a ...

Background

Iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

is a metal that has fundamentally affected the way of life of human beings ever since the

Iron Age The Iron Age () is the final epoch of the three historical Metal Ages, after the Chalcolithic and Bronze Age. It has also been considered as the final age of the three-age division starting with prehistory (before recorded history) and progre ...

. It is relatively abundant and can easily be extracted and modified due to its useful material properties, all of which result in low prices. After the

Industrial Revolution The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succee ...

(18-19th century), iron became a core material of industrial markets, its importance reflected in the phrase “iron is nation”; its production was directly regarded as an indication of national power. Especially after

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, governments vigorously supported the growth of an iron industrial market, which significantly contributed to the development of a global economy. Iron is extracted from its ore and smelted in a metallurgical furnace called a "

". The blast furnace method is expected to survive into the 22nd century because of its efficient rate of iron production at competitive costs compared with other iron-making methods. Blast furnaces keep on improving with adaptations arising from new technologies driven by rising global demand, yet the main chemical process remains the same. But process improvement cannot solve many of the problems associated with blast furnaces. The rate of iron production is highly influenced by fluctuations in the world economy, and improving the operational efficiency of the process is of major concern. However, the biggest drawback of blast furnace operation is the inevitable

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

production from iron reduction processes, which is considered one of the major contributors in

global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...

. Accordingly, the Pulverized Coal Injection (PCI) method is becoming an internationally popular method for improving blast furnace operation.

Pulverized coal injection method

Pulverized coal injection was developed in the 19th century, but was not implemented industrially until the 1970s. Rises in the cost of coke due to increased global demand and thus more competition for the resource have made this method attractive to the iron-producing industries and increased its value. The PCI method is based on the simple concept of primary air (termed the "conveying gas") carrying pulverized coal which injected through a lance to the

tuyere A tuyere or tuyère (; ) is a tube, nozzle or pipe allowing the blowing of air into a furnace or hearth.W. K. V. Gale, The iron and Steel industry: a dictionary of terms (David and Charles, Newton Abbot 1972), 216–217. Air or oxygen is i ...

(mid-bottom inlet of a blast furnace), then mixed with secondary hot air (termed the "blast") supplied through a blowpipe in the tuyere and then piped to a furnace to create a balloon-like cavity called a "raceway", which then propagates coal and coke combustion and melts the solid iron ore, releasing molten iron. The most remarkable aspect of this method is that it allows for cheaper coal to be consumed in the system, replace expensive coke, thereby remarkably cutting down on costs. Because of the extreme heat inside the furnace (>2000 Kelvin), visual observation of raceway shape and size is impossible, so remotely measuring sensors are used to investigate the chemical and physical reactions inside the furnace. Better understanding of the raceway and PCI method can optimize the performance of a blast furnace and reduce costs. Further improvements to the PCI method and the use of coal blend (mixing different coals) injection methods are attracting industry.

References

{{reflist Steelmaking