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 "forced" or supplied above atmospheric ...

Background

Iron Iron () is a chemical element with symbol Fe (from la, ferrum) 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, right in f ...

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-age division of the prehistory and protohistory of humanity. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic) and the Bronze Age (Chalcolithic). The concept has been mostly appl ...

. 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 was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

(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, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, 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 Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron Iron () is a chemical element with symbol Fe (from l ...

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 (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

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

global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

. 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 through which air is blown 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 injec ...

(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 severe environment inside the furnace, (>2000K), visual observation of raceway shape and size is impossible, therefore 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