Materials ProcessingProfessor: Clark Greene

Raw materials

IRON

Students:

Ailson Alves Timothy White

Fallou Diop

INTRODUCTION

Why talk about iron?

- It is important study and talk about iron because it is one of the most important metals to the humanity. Today in almost everything built by the man is possible to find iron (soft iron, steel or cast iron) such as car parts, aircrafts, buildings etc.

- Iron is the second metal most abundant in the earth’s crust, the first is aluminum.

- Once studying materials processing, iron is an excellent example of a material which chemical, heating, and physical processing can change many properties such as malleability, ductility, tensile strength, compression strength etc.

- Iron is found in the earth as iron ore or iron oxide and in its pure form it is just found in meteorite.

DISCOVER

- The use of Iron is related from 3,000 years ago in Egypt and part of Asia.

- As a result of proprieties better than bronze, the Iron became the principal material to make many objects such as swords, pans, and tools in 1200 B.C, as a result, this time became known as Iron era.

- The iron continued being used as material basis of human civilization in Europe, Asia, and Africa until to be replaced by steel in the 19th century.

- The first iron mining and smelting points are related to a region where today is Turkey.

IRON

Pure iron is a soft, grayish-white metal. Although iron is a common element, pure iron is almost never found in nature. The only pure iron known to exist naturally comes from fallen meteorites. Most iron is found in minerals formed by the combination of iron with other elements. Iron oxides are the most common. Those minerals near the surface of the earth that have the highest iron content are known as iron ores and are mined commercially.

• The most common iron ore are: Hematite, Fe2O3 (70% Fe); goethite, Fe2O3s H2O, (63% Fe); limonite, a mixture of hydrated iron oxides (up to 60% Fe); and magnetite, Fe3O4(72% Fe).

WHERE IS IT LOCATED?

• Only 50 countries in the world produce iron ore, but the 7 largest producers are the responsible for more than 4/5 of the product.

EXTRACTION AND PROCESSING

1. Blast2. Mining3. Crushing4. Concentrating5. Mixing6. Pelletizing7. Iron making ( Melting)

• Mining and blast • Mining iron begins at the ground level.• After drilling and blasting mines Iron ore is found , rock

which contains iron oxide.

• Crushing • Chunks as large as five feet are reduced to six inches or

less.• More than 6,000 tons of iron ore rock can be crushed

approximately in one hour.

• pelletizing

• A Pellet plant contains a series of balling drums where the iron formed into soft pellets same size of a marble between (¼’’ and ½’’)

•• Sinter: Small balls contained Iron ore, limestone and coke.

It is a little bit bigger that the pellets.

» Iron making: The materials for iron making- Iron ore, coke, sinter/pellets and limestone. The primary purpose of melting the iron ore in a blast furnace is to reduce the iron oxide to iron which, in the process become saturated with carbon also known as cast or pig iron.

The high content of carbon makes the iron brittle; it is an example of how the chemical processing may alter the properties of a material. Cast iron is good to make objects to be used sob compression and to work sob abrasion, but this material is not flexible and to fashion any piece is necessary casting, because mechanical processing is so difficult.

Fig 3: Iron making steps: mining process, crushing and pelletizing, and the last is melting.

» MANUFACTURING

The cast iron or pig iron is the material base for many others, such as different kinds of steel and iron with different contents of carbon. The process to reduce the carbon content of the pig iron had different names since the first time it was used, such as Bessemer process, Thomas Basic, and the most utilized today it the Oxygen basic process. These three processes consist of the same idea, it is to charge the blast furnace (place where iron is melted) with iron and coke and blast oxygen to this mixture, the oxygen react with the carbon when the iron is heated and it makes the iron with a low content of carbon, this iron could be used to make steel or it is used as an iron low carbon also known as soft or wrought iron. In the Thomas basic and the Oxygen basic processes limestone is also charged in the blast furnace when the pig iron is melted. The limestone is used in order to reduce the content of some impurities, for example, phosphorus, sulfur, and silicon.

FINAL PRODUCTS FROM IRON

» Cast Iron= It is iron alloy with high content of carbon (2-4.5%), silicon, manganese, sulfur, and phosphorus.

» Properties: It works good when used sob compression, it has high abrasion resistance and because that it is used to mining tools, but it tends to be brittle and is difficult to work mechanically.

» Applications: Cylinder block, Cylinder heads, tools and mining machines parts, piping, and structural connectors in building.

Wrought iron: Iron usually with less than 0.1% of carbon content and between 1 and 2% of slag. Properties: tough and malleable.

Applications: Eiffel Tower in Paris and Victorian Era Bridge in London are example of applications.

Steel: An Alloy of Iron and carbon and manganese, the carbon content is between 0.2 and 1.5% and the manganese content is less than 1%. Although, other alloy metals are used to produce specific properties.

• Less carbon in the alloys makes it ductile, very soft and weak. Too much carbon makes it brittle and not malleable.

• Steel applications

» Construction= Bridges, building, tunnels.» Transport= Car parts, jet engine components, aircrafts.» Energy= Wind turbines, oil and gas wells and platforms,

pipeline.» Appliances and Industry= Fridges, washing machines,

storage tanks, tools, structures, walkways, protective equipment etc.

» DIFFERENT WAYS TO USE THE IRON

» Powdered iron: used in metallurgy products, magnets, high-frequency cores, auto parts, catalyst.

» Radioactive iron (iron 59): in medicine, tracer element in biochemical and metallurgical research.

» Iron blue: in paints, printing inks, plastics, cosmetics (eye shadow), artist colors, laundry blue, paper dyeing, fertilizer ingredient, baked enamel finishes for autos and appliances, industrial finishes.

» Black iron oxide: as pigment, in polishing compounds, metallurgy, medicine, magnetic inks, in ferrites for electronics industry.

Sources Consulted

» “Iron and Steel Industry.” Encyclopedia Britannica, Volume 12. Chicago: Encyclopedia Britannica, 1968.

» Hartley, Edward N. Iron and Steel Works of the World. International Publication, 1987.

» "SUNIL STEEL - Iron & Steel Manufacturing Process." SUNIL STEEL - Iron & Steel Manufacturing Process. N.p., n.d. Web. 05 Feb. 2014.

» Australian atlas of mineral resources mines and processing centers: http :// www.australianminesatlas.gov.au/education/fact_sheets/i ron.html

» Britannica academic edition: http :// www.britannica.com/EBchecked/topic/98324/cast-iron

Ways to use the Iron.

Powdered iron: used in metallurgy products, magnets, high-frequency cores, auto parts, catalyst. Radioactive iron (iron 59): in medicine, tracer element in biochemical and metallurgical research. Iron blue: in paints, printing inks, plastics, cosmetics (eye shadow), artist colors, laundry blue, paper dyeing, fertilizer ingredient, baked enamel

finishes for autos and appliances, industrial finishes. Black iron oxide: as pigment, in polishing compounds, metallurgy, medicine, magnetic inks, in ferrites for electronics industry.

Background

Iron is one of the most common elements on earth. Nearly every construction of man

contains at least a little iron. It is also one of the oldest metals and was first fashioned

into useful and ornamental objects at least 3,500 years ago.

Pure iron is a soft, grayish-white metal. Although iron is a common element, pure iron is

almost never found in nature. The only pure iron known to exist naturally comes from

fallen meteorites. Most iron is found in minerals formed by the combination of iron with

other elements. Iron oxides are the most common. Those minerals near the surface of

the earth that have the highest iron content are known as iron ores and are mined

commercially.

Iron ore is converted into various types of iron through several processes. The most

common process is the use of a blast furnace to produce pig iron which is about 92-

94% iron and 3-5% carbon with smaller amounts of other elements. Pig iron has only

limited uses, and most of this iron goes on to a steel mill where it is converted into

various steel alloys by further reducing the carbon content and adding other elements

such as manganese and nickel to give the steel specific properties.

History

Historians believe that the Egyptians were the first people to work with small amounts of

iron, some five or six thousand years ago. The metal they used was apparently

extracted from meteorites. Evidence of what is believed to be the first example of iron

mining and smelting points to the ancient Hittite culture in what is now Turkey. Because

iron was a far superior material for the manufacture of weapons and tools than any

other known metal, its production was a closely guarded secret. However, the basic

technique was simple, and the use of iron gradually spread. As useful as it was

compared to other materials, iron had disadvantages. The quality of the tools made

from it was highly variable, depending on the region from which the iron ore was taken

and the method used to extract the iron. The chemical nature of the changes taking

place during the extraction were not understood; in particular, the importance of carbon

to the metal's hardness. Practices varied widely in different parts of the world. There is

evidence, for example, that the Chinese were able to melt and cast iron implements

very early, and that the Japanese produced amazing results with steel in small

amounts, as evidenced by heirloom swords dating back centuries. Similar

breakthroughs were made in the Middle East and India, but the processes never

emerged into the rest of the world. For centuries the Europeans lacked methods for

heating iron to the melting point at all. To produce iron, they slowly burned iron ore with

wood in a clay-lined oven. The iron separated from the surrounding rock but never quite

melted. Instead, it formed a crusty slag which was removed by hammering. This

repeated heating and hammering process mixed oxygen with the iron oxide to produce

iron, and removed the carbon from the metal. The result was nearly pure iron, easily

shaped with hammers and tongs but too soft to take and keep a good edge. Because

the metal was shaped, or wrought, by hammering, it came to be called wrought iron.

Tools and weapons brought back to Europe from the East were made of an iron that

had been melted and cast into shape. Retaining more carbon, cast iron is harder than

wrought iron and will hold a cutting edge. However, it is also more brittle than wrought

iron. The European iron workers knew the Easterners had better iron, but not the

processes involved in fashioning stronger iron products. Entire nations launched efforts

to discover the process.

The first known European breakthrough in the production of cast iron, which led quickly

to the first practical steel, did not come until 1740. In that year, Benjamin Huntsman took

out a patent for the melting of material for the production of steel springs to be used in

clockmaking. Over the next 20 years or so, the procedure became more widely

adopted. Huntsman used a blast furnace to melt wrought iron in a clay crucible. He then

added carefully measured amounts of pure charcoal to the melted metal. The resulting

alloy was both strong and flexible when cast into springs. Since Huntsman was

originally interested only in making better clocks, his crucible steel led directly to the

development of nautical chronometers, which, in turn, made global navigation possible

by allowing mariners to precisely determine their east/west position. The fact that he

had also invented modern metallurgy was a side-effect which he apparently failed to

notice.

Raw Materials

The raw materials used to produce pig iron in a blast furnace are iron ore, coke, sinter,

and limestone. Iron ores are mainly iron oxides and include magnetite, hematite,

limonite, and many other rocks. The iron content of these ores ranges from 70% down

to 20% or less. Coke is a substance made by heating coal until it becomes almost pure

carbon. Sinter is made of lesser grade, finely divided iron ore which, is roasted with

coke and lime to remove a large amount of the impurities in the ore. Limestone occurs

naturally and is a source of calcium carbonate.

Other metals are sometimes mixed with iron in the production of various forms of steel,

such as chromium, nickel, manganese, molybdenum, and tungsten.

The Ore Extraction and Refining Process

Before iron ore can be used in a blast furnace, it must be extracted from the ground and

partially refined to remove most of the impurities.

Leaning on his long tongs, this young iron puddler's helper posed for this photograph in

the early 1860s, when the Sons of Vulcan was a young union.

(From the collections of Henry Ford Museum & Greenfield Village.)

Historically, iron was produced by the hot-blast method, or later, the anthracite furnace.

Either way, the fundamental activity in iron making involved a worker stirring small

batches of pig iron and cinder until the iron separated from the slag. Called "puddling,"

this was highly skilled work, but was also hot, strenuous, and dangerous. It required a

lot of experience as well as a hearty constitution. Puddlers were proud, independent,

and highly paid.

Puddlers founded the first trade union in the iron and steel industry, the Sons of Vulcan,

in Pittsburgh in 1858. In 1876, this union merged with three other labor organizations to

form the Amalgamated Association of Iron and Steel Workers. This was the union that

Andrew Carnegie defeated in the Homestead Strike of 1892, leaving the union in

shambles and the industry essentially unorganized until the 1930s.

William S. Pretzer

Extraction

1 Much of the world's iron ore is extracted through open pit mining in which the

Pure iron is a soft, grayish-white metal. Although iron is a common element, pure

iron is almost never found in nature. Minerals near the surface of the earth that

have the highest iron content are known as iron ores and are mined

commercially.

surface of the ground is removed by heavy machines, often over a very large

area, to expose the ore beneath. In cases where it is not economical to remove

the surface, shafts are dug into the earth, with side tunnels to follow the layer of

ore.

Refining

2 The mined ore is crushed and sorted. The best grades of ore contain over 60%

iron. Lesser grades are treated, or refined, to remove various contaminants

before the ore is shipped to the blast furnace. Collectively, these refining

methods are called beneficiation and include further crushing, washing with water

to float sand and clay away, magnetic separation, pelletizing, and sintering. As

more of the world's known supply of high iron content ore is depleted, these

refining techniques have become increasingly important.

3 The refined ore is then loaded on trains or ships and transported to the blast

furnace site.

The Manufacturing Process

Charging the blast furnace

1 After processing, the ore is blended with other ore and goes to the blast

furnace. A blast furnace is a tower-shaped structure, made of steel, and lined

with refractory, or heat-resistant bricks. The mixture of raw material, or charge,

enters at the top of the blast furnace. At the bottom of the furnace, very hot air is

blown, or blasted, in through nozzles called tuye'res. The coke burns in the

presence of the hot air. The oxygen in the air reacts with the carbon in the coke

to form carbon monoxide. The carbon monoxide

then reacts with the iron ore to form carbon dioxide and pure iron.

Separating the iron from the slag

2 The melted iron sinks to the bottom of the furnace. The limestone combines

with the rock and other impurities in the ore to form a slag which is lighter than

the iron and floats on top. As the volume of the charge is reduced, more is

continually added at the top of the furnace. The iron and slag are drawn off

separately from the bottom of the furnace. The melted iron might go to a further

alloying process, or might be cast into ingots called pigs. The slag is carried

away for disposal.

Treating the gases

3 The hot gases produced in the chemical reactions are drawn off at the top and

routed to a gas cleaning plant where they are cleaned, or scrubbed, and sent

back into the furnace; the remaining carbon monoxide, in particular, is useful to

the chemical reactions going on within the furnace.

A blast furnace normally runs day and night for several years. Eventually the

brick lining begins to crumble, and the furnace is then shut down for

maintenance.

Quality Control

The blast furnace operation is highly instrumented and is monitored continuously. Times

and temperatures are checked and recorded. The chemical content of the iron ores

received from the various mines are checked, and the ore is blended with other iron ore

to achieve the desired charge. Samples are taken from each pour and checked for

chemical content and mechanical properties such as strength and hardness.

Byproducts/Waste

There are a great many possible environmental effects from the iron industry. The first

and most obvious is the process of open pit mining. Huge tracts of land are stripped to

bare rock. Today, depleted mining sites are commonly used as landfills, then covered

over and landscaped. Some of these landfills themselves become environmental

problems, since in the recent past, some were used for the disposal of highly toxic

substances which leached into soil and water.

The process of extracting iron from ore produces great quantities of poisonous and

corrosive gases. In practice, these gases are scrubbed and recycled. Inevitably,

however, some small amounts of toxic gases escape to the atmosphere.

A byproduct of iron purification is slag, which is produced in huge amounts. This

material is largely inert, but must still be disposed of in landfills.

Ironmaking uses up huge amounts of coal. The coal is not used directly, but is first

reduced to coke which consists of almost pure carbon. The many chemical byproducts

of coking are almost all toxic, but they are also commercially useful. These products

include ammonia, which is used in a vast number of products; phenol, which is used to

make plastics, cutting oils, and antiseptics; cresols, which go into herbicides, pesticides,

pharmaceuticals, and photographic chemicals; and toluene, which is an ingredient in

many complex chemical products such as solvents and explosives.

Scrap iron and steel—in the form of old cars, appliances and even entire steel-girdered

buildings—are also an environmental concern. Most of this material is recycled,

however, since steel scrap is an essential resource in steelmaking. Scrap which isn't

recycled eventually turns into iron oxide, or rust, and returns to the ground.

The Future

On the surface, the future of iron production—especially in the United States—appears

troubled. Reserves of high-quality ore have become considerably depleted in areas

where it can be economically extracted. Many long-time steel mills have closed.

However, these appearances are deceiving. New ore-enrichment techniques have

made the use of lower-grade ore much more attractive, and there is a vast supply of

that ore. Many steel plants have closed in recent decades, but this is largely because

fewer are needed. The efficiency of blast furnaces alone has improved remarkably. At

the beginning of this century, the largest blast furnace in the United States produced

644 tons of pig iron a day. It is believed that soon the possible production of a single

furnace will reach 4,000 tons per day. Since many of these more modern plants have

been built overseas, it has actually become more economical in some cases to ship

steel across the ocean than to produce it in older U.S. plants.

Where To Learn More

Books

Lambert, Mark. Spotlight on Iron and Steel. Rourke Enterprises, 1988.

Hartley, Edward N. Iron and Steel Works of the World. International Publication, 1987.

Lewis, W. David. Iron and Steel in America. Hagley Museum, 1986.

Walker, R. D. Modern Ironmaking Methods. Gower Publication, 1986.

— Joel Simon

Read more: http://www.madehow.com/Volume-2/Iron.html#ixzz2rkB7jhzh The production of iron by humans began probably sometime after 2000 BCE in south-west or south-central Asia, perhaps in the Caucasus region.  Thus began the Iron Age, when iron replaced bronze in implements and weapons. This shift occurred because iron, when alloyed with a bit of carbon, is harder, more durable, and holds a sharper edge than bronze.  For over three thousand years, until replaced by steel after CE 1870, iron formed the material basis of human civilization in Europe, Asia, and Africa.             Iron is the fourth most abundant element and makes up more than five percent of the earth’s crust.  Iron exists naturally in iron ore (sometimes called ironstone). Since iron has a strong affinity for oxygen, iron ore is an oxide of iron; it also contains varying quantities of other elements such as silicon, sulfur, manganese, and phosphorus. Smelting is the process by which iron is extracted from iron ore.  When iron ore is heated in a charcoal fire, the iron ore begins to release some of its oxygen, which combines with carbon monoxide to form carbon dioxide.  In this way, a spongy, porous mass of relatively pure iron is formed, intermixed with bits of charcoal and extraneous matter liberated from the ore, known as slag. (The separation of slag from the iron is facilitated by the addition of flux, that is, crushed seashells or limestone.)  The formation of this bloom of iron was as far as the primitive blacksmith got: he would remove this pasty mass from the furnace and hammer it on an anvil to drive out the cinders and slag and to compact the metallic particles.  This was wrought iron(“wrought” means “worked,” that is, hammered) and contained generally from .02 to .08 percent of carbon (absorbed from the charcoal), just enough to make the metal both

tough and malleable.  Wrought iron was the most commonly produced metal through most of the Iron Age.             At very high temperatures (rare except in a blast furnace -- see below), a radical change takes place: the iron begins to absorb carbon rapidly, and the iron starts to melt, since the higher carbon content lowers the melting point of the iron. The result is cast iron, which contains from 3 to 4.5 percent carbon. This high proportion of carbon makes cast iron hard and brittle; it is liable to crack or shatter under a heavy blow, and it cannot be forged (that is, heated and shaped by hammer blows) at any temperature.  By the late Middle Ages, European ironmakers had developed the blast furnace, a tall chimney-like structure in which combustion was intensified by a blast of air pumped through alternating layers of charcoal, flux, and iron ore. (Medieval ironworkers also learned to harness water wheels to power bellows to pump the air through blast furnaces and to power massive forge hammers; after 1777, James Watt’s new steam engine was also used for these purposes.)   Molten cast iron would run directly from the base of the blast furnace into a sand trough which fed a number of smaller lateral troughs; this configuration resembled a sow suckling a litter of piglets, and cast iron produced in this way thus came to be called pig iron.  Iron could be cast directly into molds at the blast furnace base or remelted from pig iron to make cast iron stoves, pots, pans, firebacks, cannon, cannonballs, or bells (“to cast” means to pour into a mold, hence the name “cast iron”). Casting is also called founding and is done in afoundry.             Ironmakers of the late Middle Ages also learned how to transform cast pig iron into the more useful wrought iron by oxidizing excess carbon out of the pig iron in a charcoal furnace called a finery.  After 1784, pig iron was refined in a puddling furnace (developed by the Englishman Henry Cort).  The puddling furnace required the stirring of the molten metal, kept separate from the charcoal fire, through an aperture by a highly skilled craftsman called a puddler; this exposed the metal evenly to the heat and combustion gases in the furnace so that the carbon could be oxidized out.  As the carbon content decreases, the melting point rises, causing semi-solid bits of iron to appear in the liquid mass.  The puddler would gather these in a single mass and work them under a forge hammer, and then the hot wrought iron would be run through rollers (in rolling mills) to form flat iron sheets or rails; slitting mills cut wrought iron sheets into narrow strips for making nails.  

While blast furnaces produced cast iron with great efficiency, the process of refining cast iron into wrought iron remained comparatively inefficient into the mid-1800s.  Historian David Landes writes: “The puddling furnace remained the bottleneck of the industry. Only men of remarkable strength and endurance could stand up to the heat for hours, turn and stir the thick porridge of liquescent metal, and draw off the blobs of pasty wrought iron.  The puddlers were the aristocracy of the proletariat, proud, clannish, set apart by sweat and blood.  Few of them lived past forty.  Numerous efforts were made to mechanize the puddling furnace – in vain.  Machines could be made to stir the bath, but only the human eye and touch could separate out the solidifying decarburized metal.  The size of the furnace and productivity gains were limited accordingly” (The Cambridge Economic History of Europe, Vol. VI, Part I, 1966, p. 447). 

            Another important discovery in the 1700s (by the Englishman Abraham Darby) was that coke (a contraction of “coal-cake”), or coal baked to remove impurities such as sulfur, could be substituted for charcoal in smelting. This was an important advance since charcoal production had led to severe deforestation across western Europe and Great Britain.             Steel has a carbon content ranging from .2 to 1.5 percent, enough carbon to make it harder than wrought iron, but not so much as to make it as brittle as cast iron.  Its hardness combined with its flexibility and tensile strength make steel far more useful than either type of iron: it is more durable and holds a sharp edge better than the softer wrought iron, but it resists shock and tension better than the more brittle cast iron.  However, until the mid 1800s, steel was difficult to manufacture and expensive.  Prior to the invention of the Bessemer converter (described below), steel was made mainly by the so-called cementation process.  Bars of wrought iron would be packed in powdered charcoal, layer upon layer, in tightly covered stone boxes and heated.  After several days of heating, the wrought iron bars would absorb carbon; to distribute the carbon more evenly, the metal would be broken up, rebundled with charcoal powder, and reheated.  The resulting blister steel would then be heated again and brought under a forge hammer to give it a more consistent texture.  In the 1740s, the English clockmaker Benjamin Huntsman, searching for a higher-quality steel for making clock springs, discovered that blister steel could be melted in clay crucibles and further refined by the addition of a special flux that removed fine particles of slag that the cementation process could not remove.  This was called crucible steel; it was of a high quality, but expensive.             To sum up so far:  wrought iron has a little carbon (.02 to .08 percent), just enough to make it hard without losing its malleability.  Cast iron, in contrast, has a lot of carbon (3 to 4.5 percent), which makes it hard but brittle and nonmalleable.  In between these is steel, with .2 to 1.5 percent carbon, making it harder than wrought iron, yet malleable and flexible, unlike cast iron.  These properties make steel more useful than either wrought or cast iron, yet prior to 1856, there was no easy way to control the carbon level in iron so as to manufacture steel cheaply and efficiently.  Yet the growth of railroads in the 1800s created a huge market for steel.  The first railroads ran on wrought iron rails which were too soft to be durable.  On some busy stretches, and on the outer edges of curves, the wrought iron rails had to be replaced every six to eight weeks.  Steel rails would be far more durable, yet the labor- and energy-intensive process of cementation made steel prohibitively expensive for such large-scale uses.             The mass-production of cheap steel only became possible after the introduction of the Bessemer process, named after its brilliant inventor, the British metallurgist Sir Henry Bessemer (1813-1898).  Bessemer reasoned that carbon in molten pig iron unites readily with oxygen, so a strong blast of air through molten pig iron should convert the pig iron into steel by reducing its carbon content.  In 1856 Bessemer designed what he called a converter, a large, pear-shaped receptacle with holes at the bottom to allow the injection of compressed air.  Bessemer filled it with molten pig iron, blew compressed air through the molten metal, and found that the pig iron was indeed emptied of carbon and silicon in just a few minutes; moreover, instead of freezing up from the blast of cold air, the metal became even hotter and so remained molten. 

Subsequent experimentation by another British inventor, Robert Mushet, showed that the air blast actually removed too much carbon and left too much oxygen behind in the molten metal.  This made necessary the addition of a compound of iron, carbon, and manganese called spiegeleisen (or spiegel for short):  the manganese removes the oxygen in the form of manganese oxide, which passes into the slag, and the carbon remains behind, converting the molten iron into steel. (Ferromanganese serves a similar purpose.) The blast of air through the molten pig iron, followed by the addition of a small quantity of molten spiegel, thus converts the whole large mass of molten pig iron into steel in just minutes, without the need for any additional fuel (as contrasted with the days, and tons of extra fuel and labor, required for puddling and cementation).             One shortcoming of the initial Bessemer process, however, was that it did not remove phosphorus from the pig iron.  Phosphorus makes steel excessively brittle.  Initially, therefore, the Bessemer process could only be used on pig iron made from phosphorus-free ores.  Such ores are relatively scarce and expensive, as they are found in only a few places (e.g. Wales and Sweden, where Bessemer got his iron ore, and upper Michigan).  In 1876, the Welshman Sidney Gilchrist Thomas discovered that adding a chemically basic material such as limestone to the converter draws the phosphorus from the pig iron into the slag, which floats to the top of the converter where it can be skimmed off, resulting in phosphorus-free steel.(This is called the basic Bessemer process, or the Thomas basic process.) This crucial discovery meant that vast stores of iron ore from many regions of the world could be used to make pig iron for Bessemer converters, which in turn led to skyrocketing production of cheap steel in Europe and the U.S.  In the U.S., for example, in 1867, 460,000 tons of wrought iron rails were made and sold for $83 per ton; only 2550 tons of  Bessemer steel rails were made, fetching a price of up to $170 per ton. By 1884, in contrast, iron rails had virtually ceased to be made at all; steel rails had replaced them at an annual production of 1,500,000 tons selling at a price of $32 per ton. Andrew Carnegie’s genius for lowering production costs would drive prices as low as $14 per ton before the end on the century.  (This drop in cost was accompanied by an equally dramatic increase in quality as steel replaced iron rails: from 1865 to 1905, the average life of a rail increased from two years to ten and the car weight a rail could bear increased from eight tons to seventy.)             The Bessemer process did not have the field to itself for long as inventors sought ways around the patents (over 100 of them) held by Henry Bessemer.  In the 1860s, a rival appeared on the scene: the open-hearth process, developed primarily by the German engineer Karl Wilhelm Siemens. This process converts iron into steel in a broad, shallow, open-hearth furnace (also called a Siemens gas furnace since it was fueled first by coal gas, later by natural gas) by adding wrought iron or iron oxide to molten pig iron until the carbon content is reduced by dilution and oxidation. Using exhaust gases to preheat air and gas prior to combustion, the Siemens furnace could achieve very high temperatures.  As with Bessemer converters, the use of basic materials such as limestone in open-hearth furnaces helps to remove phosphorus from the molten metal (a modification called the basic open-hearth process).  Unlike the Bessemer converter, which makes steel in one volcanic rush, the open-hearth process takes hours and allows for periodic laboratory testing of the molten steel so that steel can be made to the precise specifications of the customer as to chemical composition

and mechanical properties.  The open hearth process also allows for the production of larger batches of steel than the Bessemer process and the recycling of scrap metal.  Because of these advantages, by 1900 the open hearth process had largely replaced the Bessemer process.  (After 1960, it was in turn replaced by the basic oxygen process, a modification of the Bessemer process, in the production of steel from iron ore, and by the electric-arc furnace in the production of steel from scrap.)             Unlike many of his competitors, Andrew Carnegie was quick to recognize the importance of the Bessemer, Thomas basic, and open-hearth processes.  He was also among the first steelmakers to grasp the vital importance of chemistry in steelmaking.  These became keys to his success as a steel manufacturer.             The mass production of cheap steel, made possible by the discoveries described above (and many others not mentioned), has revolutionized our world.  Consider a brief and incomplete list of the products made possible (or better or more affordable) by cheap, abundant steel: railroads, oil and gas pipelines, refineries, power plants, power lines, assembly lines, skyscrapers, elevators, subways, bridges, reinforced concrete, automobiles, trucks, buses, trolleys, refrigerators, washing machines, clothes dryers, dishwashers, nails, screws, bolts, nuts, needles, wire, watches, clocks, canned food, battleships, aircraft carriers, oil tankers, ocean freighters, shipping containers, cranes, bulldozers, tractors, farm implements, fences, knives, forks, spoons, scissors, razors, surgical instruments, ball-bearings, turbines, drill bits, saws, and tools of every sort. 

In view of his moral failings, can we really consider Carnegie a “portrait of human greatness?”  The case for an affirmative answer is this. We are heirs to thousands of years of technological progress, and we benefit every day from the ingenuity and hard work of many thousands of blacksmiths, ironworkers, steelworkers, engineers, inventors, chemists, metallurgists, and entrepreneurs, long since deceased, one of whom was Carnegie and few of whom were saints. Our standard of living today owes much to Carnegie’s entrepreneurial drive, self-education, and genius for efficiency. Whatever his flaws – and who among us has none? – Carnegie embodied a type of human greatness that deserves our appreciation and gratitude.  Without forgetting the contributions of others (especially his workers), we should make the same judgment about Carnegie that Stephen Ambrose makes about the men who built the first transcontinental railroad: “Things happened as they happened.  It is possible to imagine all kinds of different routes across the continent, or a better way for the government to help private industry, or maybe to have the government build and own it.  But those things didn’t happen, and what did take place is grand.  So we admire those who did it – even if they were far from perfect – for what they were and what they accomplished and how much each of us owes them.” (Nothing Like It In the World [New York: Simon and Schuster: 2000], p. 382)

     

Sources Consulted

 Ashton, T.S. Iron and Steel In the Industrial Revolution. New York: Augustus M. Kelley, 1968. Carnegie, Andrew. The Autobiography of Andrew Carnegie. Boston: Northeastern University Press, 1986. Carnegie, Andrew. The Empire of Business. New York: Doubleday, Page & Co., 1902.  (See esp. “Steel Manufacture in the United States in the Nineteenth Century,” pp. 229-242.) Chard, Jack. Making Iron and Steel: The Historic Processes, 1700-1900. Ringwood, NJ: North Jersey Highlands Historical Society, 1995. Fisher, Douglas Alan. The Epic of Steel. New York: Harper and Row, 1963. “Iron and Steel Industry.” Encyclopedia Britannica, Volume 12. Chicago: Encyclopedia Britannica, 1968. Landes, David. “Technological Change and Development in Western Europe, 1750-1914,” in Postan and Habakkuk eds., The Cambridge Economic History of Europe, Volume VI, Part I. Cambridge: Cambridge University Press, 1965, pp. 274-601, esp. pp. 444-8 and 477-496. Livesay, Harold C. Andrew Carnegie and the Rise of Big Business. HarperCollins Publishers, 1975. Pounds, Norman J.G. The Geography of Iron and Steel. Second edition. London: Hutchinson University Library, 1963. Rosenberg, Nathan and L.E. Birdzell, Jr. How the West Grew Rich: The Economic Transformation of the Industrial World.  New York: Basic Books, 1986. Stubbles, John. “The Basic Oxygen Steelmaking Process.”  American Iron and Steel Institute Steelworks Learning Center. http://www.steel.org/learning/howmade/bos_process.htm Wall, Joseph Frazier. Andrew Carnegie. Second edition. Pittsburgh: University of Pittsburgh Press, 1989.