IRON AND STEEL
Iron and the iron alloy, steel, are the most useful of all metals. It is hard to think of an object which doesn't have iron or steel in them or require machines made with iron and steel to make them.
Iron is an element. It is rarely found pure in nature. It is usually mined in an iron oxide ore such as hematite,, magnetite and taconite. Hematite is by far the most abundant iron ore found near the surface of the earth.
Steel is an iron alloy with carbon from coke, limestone and metals such as chromium or manganese that added depending on the desired characteristics of the steel. There are two main kinds of steel: carbon steels (with iron, carbon and manganese as the primary ingredients) and alloy steels (with substances such as molyendeum, nickel, tungsten, vanadium or chromium that changes the character of the metal).
Mineral and Energy Production : United States Geological Survey (USGS) Minerals Resources Program minerals.usgs.gov/minerals/pubs/commodity ; Index Mundi indexmundi.com/minerals/ ; Energy Information Administration, Department of Energy eia.doe.gov/emeu/international ; Nationmaster nationmaster.com
Websites and Resources on Mining: Mining.com mining.com ; Wikipedia article Wikipedia ; Mining Engineering books.google.com/books ; Geology and Hard Rock Mining rmmlf.org/scitech/ ; Mining technology mining-technology.com ;
The Iron Age began around 1,500 B.C. It followed the Stone Age, Copper Age and Bronze Age. North of Alps it was from 800 to 50 B.C. Iron was used in 2000 B.C. Improved iron working from the Hittites became wide spread by 1200 B.C.
Iron was made around 1500 B.C. by the Hitittes. About 1400 B.C., the Chalbyes, a subject tribe of the Hitittes invented the cementation process to make iron stronger. The iron was hammered and heated in contact with charcoal. The carbon absorbed from the charcoal made the iron harder and stronger. The smelting temperature was increased by using more sophisticated bellows.
Iron---a metal a that is harder, stronger and keeps an edge better than bronze---proved to be an ideal material for improving weapons and armor as well as plows (land with soil previously to hard to cultivate was able to be farmed for the first time). Although it is found all over the world, iron was developed after bronze because virtually the only source of pure iron is meteorites and iron ore is much more difficult to smelt (extract the metal from rock) than copper or tin. Some scholars speculate the first iron smelts were built on hills where funnels were used to trap and intensify wind, blowing the fire so it was hot enough to melt the iron. Later bellows were introduced and modern iron making was made possible when the Chinese and later Europeans discovered how to make hotter-burning coke from coal. [Source: "History of Warfare" by John Keegan, Vintage Books]
Metal making secrets were carefully guarded by the Hittites and the civilizations in Turkey, Iran and Mesopotamia. Iron could not be shaped by cold hammering (like bronze), it had to be constantly reheated and hammered. The best iron has traces of nickel mixed in with it. [Source: "History of Warfare" by John Keegan, Vintage Books]
About 1200 BC, scholars suggest, cultures other than the Hittites began to possess iron. The Assyrians began using iron weapons and armor in Mesopotamia around that time with deadly results, but the Egyptians did not utilize the metal until the later pharaohs. Lethal Celtic swords dating back to 950 BC have been found in Austria and its is believed the Greeks learned to make iron weapons from them. [Source: "History of Warfare" by John Keegan, Vintage Books]
Africans Invent Steel 1,900 Years before Europeans
The Haya people on the western shore of Lake Victoria in Tanzania made medium-carbon steel in preheated, forced-draft furnaces between 1,500 and 2,000 years ago. The person usually given credit with inventing steel is German-born metallurgist Karl Wilhelm who used an open hearth furnace in the 19th century to make high grade steel. The Haya made their own steel until the middle of the middle 20th century when they found it was easier to make money from raising cash crops like coffee and buy steel tools from the Europeans than it was to make their own. [Source: Time magazine, September 1979]
The discovery was made by anthropologist Peter Schmidt and metallurgy professor Donald Avery, both of Brown University. Very few of the Haya remember how to make steel but the two scholars were able to locate one man who made a traditional ten-foot-high cone shaped furnace from slag and mud. It was built over a pit with partially burned wood that supplied the carbon which was mixed with molten iron to produce steel. Goat skin bellows attached to eight ceramic tubs that entered the base of the charcoal-fueled furnace pumped in enough oxygen to achieve temperatures high enough to make carbon steel (3275 degrees F). [Ibid]
While doing excavations on the western shore of Lake Victoria Avery found 13 furnace nearly identical to the one described above. Using radio carbon dating he was astonished to find that the charcoal in the furnaces was between 1,550 and 2,000 years old. [Ibid]
Steelmaking was invented in Europe around 1860, when it was discovered that a blast of air through molten pig iron removed impurities such as sulfur that made the metal brittle. Later it was discovered that adding an iron alloy containing manganese and limestone removed the remaining impurities---oxygen, phosphorus and leftover sulfur---producing steel. Other developments such high carbon steel, adding chromium alloys, blast furnaces made steel stronger.
Iron Mining and Processing
Most iron is mined as hematite (iron ore) in open pit mines. Limestone, coal and many of the materials used in making steel also are mined. The raw materials for making iron are plentiful but they are heavy and expensive to transport. Iron and steel mills are often located near sources of limestone and coal because they are more expensive to transport than iron ore.
Pig iron is made by smelting iron ore, coke (coal that has been partly burned to get rid of impurities), and limestone in blast furnaces. The coal is converted into coke in a cooking oven. Iron is prepared in a “sintering machine.” Limestone is readied in a pellet-hardening furnace.
A blast furnace is usually several stories high and is able to hold about 40 freight cars full of iron ore. Inside the furnace blasts of air cause the coke to burn at extremely high temperatures, around 3,000̊F, and cause the ore to melt and flow downward. Impurities are separated by the heat, gases and limestone.
From time to time white hot liquid iron and melted impurities are drawn off. Some of the coke and limestone is absorbed into the iron, which make its strong and hard. The rest combines with impurities to produce slag which is lighter than the iron and is skimmed off.
Molten iron is drained off in a process called tapping and then poured into molds to produce pig iron, which is cooled with jets of water. The name pig iron dates to the 1700s when molds received molten iron from a runner that look like a suckling pig.
Blast furnaces are kept on all the time-24 hours a day, seven days a week, 365 days a year---expect for regular inspections or equipment renovation, When it shut down the meted iron turns solid and it is very difficult to start it up again
About 8 kilograms of ore, rock, soil and sand needs to be excavated to produce one kilogram of iron. [Source: Japanese Environmental Ministry]
About 5,400 pounds of raw materials are needed to make 2,000 pounds of steel. These include 1,250 pounds of pig iron, which in turn requires 2,163 pounds of iron ore, 1,371 pounds of coking coal, 397 pounds of limestone and 190 pounds of scrap and miscellaneous materials.
The 1,250 pounds of pig iron is combined 30 pounds of alloying materials, 164 pounds of iron ore, 106 pounds of limestones and 938 pounds of scarp metal. To carry out the various chemical processes 4½ tons of air and 150 tons of water are needed. Large amounts of oil, gas or electricity are needed to provide power.
It takes about one ton to 1.5 tons of coking coal to make one ton of steel. The industry that supples coking coal has become increasingly more oligopolistic, with the five top companies accounting for about 60 percent of the exports. BHP Billiton is the largest of these. In 2010 it was decided that prices would be reviewed every quarter rather than every year to reflect the volatility of the market.
Coking coal prices rose from $47.81 a ton to $78.90 a ton in early 2008. Steel firms in turn raised their prices for sheet and plate steel 10 percent to 20 percent to reflect cost increases in iron ore and coal.
Chromium is a key ingredient for stainless steel, a material used to make everything from kitchen utensils to precision tools and surgical equipment. It is resistant to heat and chemicals. This makes it a good material for making strong, corrosion-resistant alloys but also means it expensive and difficult to process. Most chromium is extracted from an ore called chromite, which contains oxygen and iron that are removed by processing.
A portion of chromium as small a 10 percent added to iron or steel makes it corrosion resistant. Chromium largely replaced nickel and zinc as the primary plating material because of its superior hardness and resistance to chemical processes. About 80 percent of world consumption of chromate is in the chemical and metallurgical industries. Many chromates are poisonous. They damaged red blood cells if they enter the skin.
Most steel is made using one of five methods: 1) open-hearth furnace; 2) Bessemer converters; 3) electric furnace; 4) the basic oxygen process; and 5) the vacuum-arc process. All of these methods require a lot of energy.
High quality grades of carbon and alloy steel such as stainless, tool, corrosion- and heat-resistant steels are made with the electric furnace and the vacuum-arc steelmaking processes because alloys can easily be added after the slag is removed..
The oxygen process is regarded as the most efficient method. In the charging phase, the furnace is tilted to receive molten iron and steel scrap. In the refining phase, the furnace receives limestone and is stoked with an injection of oxygen. In the tapping phases the refined steel is poured from the tilted furnace.
The liquid steel is poured into molds and cooled with jets of water. Often it taken to a rolling machine, which rolls it into long sheets that are rolled in cylinders and ready to be shipped. Hot rolled steel is the basic product of steel mills. Cold rolled steel is used in the manufacturing of cars.
Iron Producers and Buyers
Almost 1 billion metric tons of iron ore is mined a year. Major iron producers include Brazil, Australia, the former U.S.S.R., and China.
Demand from China has boosted the price of iron. The price of iron reached $106 in April 2010, up from $77 a ton in fiscal 2008. In 2010 it was decided that prices would be reviewed every quarter rather than every year to reflect the volatility of the market.
In 2006 and 2007 iron producers raised the price to steelmakers who in turn passed on higher prices to car manufacturers and other companies that use steel.
Three large producers control the market: BHP Billiton; the Brazilian mining company Companhia Vale do Rio Dolce (CVRD), and Rio Tinto account for 80 percent of the iron sold from Australia and Brazil, far and away the largest producers. The three companies are large and powerful enough they can set prices and have been charged with engaging in monopolistic behavior by the European Union. Anglo-Australian Rio Tinto and BHP Billiton have plans to integrate their operations in Australia.
China, Japan and South Korea are among the biggest buyers of imported iron, with China being the largest and getting larger all the time. Negotiations between these countries and the world’s largest iron ore producers---Vale, Rio Tinto and BHP Billiton---is increasingly defining the world price. During negotiations in 2009, suppliers agreed to a 33 percent cut with Japanese and South Korean buyers. China wanted even deep cuts and put some Rio Tinto executives in jail while trying to achieve that goal.
World iron Production, By Country (Thousand metric tons, 2006): 1) China 588,000; 2) Brazil 318,000; 3) Australia 275,042; 4) India 160,000; 5) Russian Federation 102,000; 6) Ukraine 74,000; 7) United States 52,700; 8) South Africa 41,326.04; 9) Canada 33,551; 10) Sweden 23,300; 11) Venezuela 23,000; 12) Iran, Islamic Republic Of 20,000; 13) Kazakhstan 18,600; 14) Mauritania 11,155; 15) Mexico 11,000; 16) Chile 8,62; 17) Peru 7,250; 18) Korea, Democratic People's Republic Of 5,000; 19) Turkey 4,000; 20) Bosnia and Herzegovina 3,300; 21) Egypt 2,500; 22) Algeria 2,33; 23) New Zealand 2,300; 24) Austria 2,000; 25) Greece 1,500 [Source: United States Geological Survey (USGS) Minerals Resources Program]
Steel is a straight forward commodity business.
World Production, By Country (Thousand metric tons, 2006): 1) China 489,240; 2) Japan 120,203; 3) United States; 4) Russian Federation; 5) India 53,100; 6) Korea, Republic Of 51,517.31; 7) Germany 48,550; 8) Ukraine 42,830; 9) Italy 31,990; 10) Brazil 31,800; 11) Turkey 25,750; 12) Taiwan, Province Of China 20,450; 13) France 19,252; 14) Spain 18,400; 15) Mexico 16,300; 16) Canada 15,56; 17) United Kingdom 14,300; 18) Belgium 11,000; 19) Poland 10,630 [Source: United States Geological Survey (USGS) Minerals Resources Program]
The worlds top producers of crude steel are (1988): 1) USSR, 2) Japan, 3) the U.S., 4) China, 5) W. Germany, 6) Brazil, 7) Italy, 8) South Korea, 9) France, 10) the UK.
The worlds top exporters of crude steel are (1988): 1) Japan, 2) W. Germany, 3) Belgium/Luxembourg, 4) France, 5) Brazil, 6) USSR, 7) South Korea, 8) Italy, 9) the UK, 10) the Netherlands.
China consumes 26 percent of the world’s steel.
The worlds top consumers of crude steel are (1988): 1) USSR, 2) the U.S., 3) Japan, 4) China, 5) W. Germany, 6), Italy, 7) the UK, 8) France, 9) India and 10) South Korea.
World demand for steel increased dramatically in the 2000s. In 2006 and 2007 iron producers raised the price to steelmakers who in turn passed on higher prices to car manufacturers and other companies that use steel.
Shortages of coking coal also caused price rises. Its supply is also controlled by a few producers who can set the price.
1) Mittal; 2) Luxembourg-based Arcelor.
Text Sources: World Almanac, United States Geological Survey (USGS) Minerals Resources Program, Investopedia Industry Handbooks, U.S. Energy Information Administration, Department of Energy and National Geographic articles. Also the New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.
© 2009 Jeffrey Hays
Last updated March 2011