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90-594: The Michigan Smelter was a copper smelter located at Cole's Creek on the Keweenaw Waterway north-west of Houghton, Michigan near the old Atlantic mill . The smelter was created in 1903-4 as a joint effort between the Copper Range Company and Stanton group of mines. An Atlantic dam on the site was reused by the smelter as a water source. In 1905, the smelter broke a world record by casting 292,000 pounds of fine copper in seven hours with

180-565: A Bessemer converter or by other means including smelting reduction processes such as the Corex Process . Smelting has serious effects on the environment , producing wastewater and slag and releasing such toxic metals as copper , silver, iron, cobalt , and selenium into the atmosphere. Smelters also release gaseous sulfur dioxide , contributing to acid rain , which acidifies soil and water. The smelter in Flin Flon, Canada

270-408: A steam engine replaced a horse-powered pump in 1742. Such engines were used to pump water to a reservoir above the furnace. The first engines used to blow cylinders directly was supplied by Boulton and Watt to John Wilkinson 's New Willey Furnace. This powered a cast iron blowing cylinder , which had been invented by his father Isaac Wilkinson . He patented such cylinders in 1736, to replace

360-453: A sulfide ), or carbon and oxygen together (as a carbonate ). To extract the metal, workers must make these compounds undergo a chemical reaction . Smelting, therefore, consists of using suitable reducing substances that combine with those oxidizing elements to free the metal. In the case of sulfides and carbonates, a process called " roasting " removes the unwanted carbon or sulfur, leaving an oxide, which can be directly reduced. Roasting

450-542: A blast furnace to melt the iron and remove the gangue (impurities) unless the ore is very high quality. The oxygen blast furnace (OBF) process has been extensively studied theoretically because of the potentials of promising energy conservation and CO 2 emission reduction. This type may be the most suitable for use with CCS. The main blast furnace has of three levels; the reduction zone (523–973 K (250–700 °C; 482–1,292 °F)), slag formation zone (1,073–1,273 K (800–1,000 °C; 1,472–1,832 °F)), and

540-448: A blast furnace, fuel ( coke ), ores , and flux ( limestone ) are continuously supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes called tuyeres , so that the chemical reactions take place throughout the furnace as the material falls downward. The end products are usually molten metal and slag phases tapped from

630-413: A bloomery does not. Another difference is that bloomeries operate as a batch process whereas blast furnaces operate continuously for long periods. Continuous operation is also preferred because blast furnaces are difficult to start and stop. Also, the carbon in pig iron lowers the melting point below that of steel or pure iron; in contrast, iron does not melt in a bloomery. Silica has to be removed from

720-549: A chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron , copper , silver , tin , lead and zinc . Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal behind. The reducing agent is commonly a fossil-fuel source of carbon , such as carbon monoxide from incomplete combustion of coke —or, in earlier times, of charcoal . The oxygen in

810-424: A hammer to produce wrought iron . Some of the earliest evidence to date for the bloomery smelting of iron is found at Tell Hammeh , Jordan, radiocarbon-dated to c.  930 BC . From the medieval period, an indirect process began to replace the direct reduction in bloomeries. This used a blast furnace to make pig iron , which then had to undergo a further process to make forgeable bar iron. Processes for

900-709: A low concentration of sulfur dioxide that was difficult to capture; a new generation of copper smelting technologies has supplanted them. More recent furnaces exploit bath smelting, top-jetting lance smelting, flash smelting , and blast furnaces. Some examples of bath smelters include the Noranda furnace, the Isasmelt furnace, the Teniente reactor, the Vunyukov smelter, and the SKS technology. Top-jetting lance smelters include

990-484: A minor branch of the industry, but Darby's son built a new furnace at nearby Horsehay, and began to supply the owners of finery forges with coke pig iron for the production of bar iron. Coke pig iron was by this time cheaper to produce than charcoal pig iron. The use of a coal-derived fuel in the iron industry was a key factor in the British Industrial Revolution . However, in many areas of

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1080-455: A model factory, often as large as the church and only several feet away, and waterpower drove the machinery of the various industries located on its floor." Iron ore deposits were often donated to the monks along with forges to extract the iron, and after a time surpluses were offered for sale. The Cistercians became the leading iron producers in Champagne , France, from the mid-13th century to

1170-481: A range of more complex organic compounds known collectively as polycyclic aromatic hydrocarbons (PAH). Treatment technologies include recycling of wastewater; settling basins , clarifiers and filtration systems for solids removal; oil skimmers and filtration; chemical precipitation and filtration for dissolved metals; carbon adsorption and biological oxidation for organic pollutants; and evaporation. Pollutants generated by other types of smelters varies with

1260-434: A secondary service after the reduction step is complete; they provide a molten cover on the purified metal, preventing contact with oxygen while still hot enough to readily oxidize. This prevents impurities from forming in the metal. The ores of base metals are often sulfides. In recent centuries, reverberatory furnaces have been used to keep the charge being smelted separately from the fuel. Traditionally, they were used for

1350-424: A single furnace and only ten men. The smelter operated through World War II and stopped all operations in 1948. The smelter was designed by Frank Klepetko and was the most modern plant in the district. The nearby hillside was used improve its efficiency of its operation. The smelter had a capacity of 90 million pounds annually and was the largest and most efficient on Lake Superior. Several mills sent material to

1440-541: Is believed to have produced cast iron quite efficiently. Its date is not yet clear, but it probably did not survive until Henry VIII 's Dissolution of the Monasteries in the late 1530s, as an agreement (immediately after that) concerning the "smythes" with the Earl of Rutland in 1541 refers to blooms. Nevertheless, the means by which the blast furnace spread in medieval Europe has not finally been determined. Due to

1530-542: Is easily produced during the heating process, and as a gas comes into intimate contact with the ore. In the Old World , humans learned to smelt metals in prehistoric times, more than 8000 years ago. The discovery and use of the "useful" metals – copper and bronze at first, then iron a few millennia later – had an enormous impact on human society. The impact was so pervasive that scholars traditionally divide ancient history into Stone Age , Bronze Age , and Iron Age . In

1620-556: Is located in Fengxiang County , Shaanxi (a museum exists on the site today). There is however no evidence of the bloomery in China after the appearance of the blast furnace and cast iron. In China, blast furnaces produced cast iron, which was then either converted into finished implements in a cupola furnace, or turned into wrought iron in a fining hearth. Although cast iron farm tools and weapons were widespread in China by

1710-408: Is occasionally found in commercially significant quantities. These minerals are primarily carbonates , sulfides , or oxides of the metal, mixed with other components such as silica and alumina . Roasting the carbonate and sulfide minerals in the air converts them to oxides. The oxides, in turn, are smelted into the metal. Carbon monoxide was (and is) the reducing agent of choice for smelting. It

1800-597: Is only marginally harder, and had even less impact by itself. The earliest evidence for iron-making is a small number of iron fragments with the appropriate amounts of carbon admixture found in the Proto-Hittite layers at Kaman-Kalehöyük and dated to 2200–2000 BC. Souckova-Siegolová (2001) shows that iron implements were made in Central Anatolia in very limited quantities around 1800 BC and were in general use by elites, though not by commoners, during

1890-464: Is possible that the technology reached Sweden by this means. The Vikings are known to have used double bellows, which greatly increases the volumetric flow of the blast. The Caspian region may also have been the source for the design of the furnace at Ferriere , described by Filarete , involving a water-powered bellows at Semogo in Valdidentro in northern Italy in 1226. In a two-stage process

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1980-562: Is unknown. The first such bronzes may have been a lucky accident from tin-contaminated copper ores. However, by 2000 BC, people were mining tin on purpose to produce bronze—which is remarkable as tin is a semi-rare metal, and even a rich cassiterite ore only has 5% tin. The discovery of copper and bronze manufacture had a significant impact on the history of the Old World . Metals were hard enough to make weapons that were heavier, stronger, and more resistant to impact damage than wood, bone, or stone equivalents. For several millennia, bronze

2070-408: Is used to make cast iron . The majority of pig iron produced by blast furnaces undergoes further processing to reduce the carbon and sulphur content and produce various grades of steel used for construction materials, automobiles, ships and machinery. Desulphurisation usually takes place during the transport of the liquid steel to the steelworks. This is done by adding calcium oxide , which reacts with

2160-423: Is usually carried out in an oxidizing environment. A few practical examples: Reduction is the final, high-temperature step in smelting, in which the oxide becomes the elemental metal. A reducing environment (often provided by carbon monoxide, made by incomplete combustion in an air-starved furnace) pulls the final oxygen atoms from the raw metal. The carbon source acts as a chemical reactant to remove oxygen from

2250-517: The Americas , pre- Inca civilizations of the central Andes in Peru had mastered the smelting of copper and silver at least six centuries before the first Europeans arrived in the 16th century, while never mastering the smelting of metals such as iron for use with weapon craft. Copper was the first metal to be smelted. How the discovery came about is debated. Campfires are about 200 °C short of

2340-774: The Chinese examples, were very inefficient compared to those used today. The iron from the Lapphyttan complex was used to produce balls of wrought iron known as osmonds , and these were traded internationally – a possible reference occurs in a treaty with Novgorod from 1203 and several certain references in accounts of English customs from the 1250s and 1320s. Other furnaces of the 13th to 15th centuries have been identified in Westphalia . The technology required for blast furnaces may have either been transferred from China, or may have been an indigenous innovation. Al-Qazvini in

2430-540: The Industrial Revolution . Hot blast was patented by James Beaumont Neilson at Wilsontown Ironworks in Scotland in 1828. Within a few years of the introduction, hot blast was developed to the point where fuel consumption was cut by one-third using coke or two-thirds using coal, while furnace capacity was also significantly increased. Within a few decades, the practice was to have a "stove" as large as

2520-545: The Ironbridge Gorge Museums. Cast iron from the furnace was used to make girders for the world's first cast iron bridge in 1779. The Iron Bridge crosses the River Severn at Coalbrookdale and remains in use for pedestrians. The steam engine was applied to power blast air, overcoming a shortage of water power in areas where coal and iron ore were located. This was first done at Coalbrookdale where

2610-492: The Lehigh Crane Iron Company at Catasauqua, Pennsylvania , in 1839. Anthracite use declined when very high capacity blast furnaces requiring coke were built in the 1870s. The blast furnace remains an important part of modern iron production. Modern furnaces are highly efficient, including Cowper stoves to pre-heat the blast air and employ recovery systems to extract the heat from the hot gases exiting

2700-619: The New Hittite Empire (~1400–1200 BC). Archaeologists have found indications of iron working in Ancient Egypt , somewhere between the Third Intermediate Period and 23rd Dynasty (ca. 1100–750 BC). Significantly though, they have found no evidence of iron ore smelting in any (pre-modern) period. In addition, very early instances of carbon steel were in production around 2000 years ago (around

2790-893: The fuel efficiency of the bloomery and improves yield. They can also be built bigger than natural draught bloomeries. The oldest known blast furnaces in the West were built in Durstel in Switzerland , the Märkische Sauerland in Germany , and at Lapphyttan in Sweden , where the complex was active between 1205 and 1300. At Noraskog in the Swedish parish of Järnboås, traces of even earlier blast furnaces have been found, possibly from around 1100. These early blast furnaces, like

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2880-463: The iron sulfide contained in the pig iron to form calcium sulfide (called lime desulfurization ). In a further process step, the so-called basic oxygen steelmaking , the carbon is oxidized by blowing oxygen onto the liquid pig iron to form crude steel . Cast iron has been found in China dating to the 5th century BC, but the earliest extant blast furnaces in China date to the 1st century AD and in

2970-413: The reverberatory furnaces . The site had two melting furnaces and two refining furnaces about seven feet below. Water-tube boilers were heated by the furnace's waste gas which were drawn up through a 150-foot smokestack. Slag was skimmed off into steel molds on cars of an electric locomotive and the copper was then drained into the refining furnaces. The slag accounted for approximately 35 percent of

3060-574: The 'dwarf" blast furnaces were found in Dabieshan . In construction, they are both around the same level of technological sophistication. The effectiveness of the Chinese human and horse powered blast furnaces was enhanced during this period by the engineer Du Shi (c. AD 31), who applied the power of waterwheels to piston - bellows in forging cast iron. Early water-driven reciprocators for operating blast furnaces were built according to

3150-662: The 13th century and other travellers subsequently noted an iron industry in the Alburz Mountains to the south of the Caspian Sea . This is close to the silk route , so that the use of technology derived from China is conceivable. Much later descriptions record blast furnaces about three metres high. As the Varangian Rus' people from Scandinavia traded with the Caspian (using their Volga trade route ), it

3240-411: The 1550s, and many were built in the remainder of that century and the following ones. The output of the industry probably peaked about 1620, and was followed by a slow decline until the early 18th century. This was apparently because it was more economic to import iron from Sweden and elsewhere than to make it in some more remote British locations. Charcoal that was economically available to the industry

3330-500: The 17th century, also using the phosphate -rich slag from their furnaces as an agricultural fertilizer . Archaeologists are still discovering the extent of Cistercian technology. At Laskill , an outstation of Rievaulx Abbey and the only medieval blast furnace so far identified in Britain , the slag produced was low in iron content. Slag from other furnaces of the time contained a substantial concentration of iron, whereas Laskill

3420-479: The 4th century AD. The primary advantage of the early blast furnace was in large scale production and making iron implements more readily available to peasants. Cast iron is more brittle than wrought iron or steel, which required additional fining and then cementation or co-fusion to produce, but for menial activities such as farming it sufficed. By using the blast furnace, it was possible to produce larger quantities of tools such as ploughshares more efficiently than

3510-511: The 5th century BC , employing workforces of over 200 men in iron smelters from the 3rd century onward, the earliest blast furnaces constructed were attributed to the Han dynasty in the 1st century AD. These early furnaces had clay walls and used phosphorus -containing minerals as a flux . Chinese blast furnaces ranged from around two to ten meters in height, depending on the region. The largest ones were found in modern Sichuan and Guangdong , while

3600-522: The Corsican, was used prior to the advent of Christianity . Examples of improved bloomeries are the Stuckofen, sometimes called wolf-furnace, which remained until the beginning of the 19th century. Instead of using natural draught, air was pumped in by a trompe , resulting in better quality iron and an increased capacity. This pumping of air in with bellows is known as cold blast , and it increases

3690-676: The Michigan Smelter including the Champion , Trimountain and Baltic mills via the Copper Range Railroad . Product originated from the Atlantic , Baltic , Champion , Trimountain , Michigan , Mohawk , and Wolverine mines. They delivered the mineral in 40-ton bottom-dumping cars and the product from each mine was kept separate from the others. The incoming product was sorted, dried and stored in hoppers above

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3780-546: The Mitsubishi smelting reactor. Flash smelters account for over 50% of the world's copper smelters. There are many more varieties of smelting processes, including the Kivset, Ausmelt, Tamano, EAF, and BF. Of the seven metals known in antiquity , only gold regularly occurs in nature as a native metal . The others – copper , lead , silver , tin , iron , and mercury – occur primarily as minerals, although native copper

3870-533: The West from the High Middle Ages . They spread from the region around Namur in Wallonia (Belgium) in the late 15th century, being introduced to England in 1491. The fuel used in these was invariably charcoal. The successful substitution of coke for charcoal is widely attributed to English inventor Abraham Darby in 1709. The efficiency of the process was further enhanced by the practice of preheating

3960-418: The ancient world. It is too soft to use for structural elements or weapons, though its high density relative to other metals makes it ideal for sling projectiles. However, since it was easy to cast and shape, workers in the classical world of Ancient Greece and Ancient Rome used it extensively to pipe and store water. They also used it as a mortar in stone buildings. Tin was much less common than lead,

4050-594: The area with higher temperatures, ranging up to 1200 °C degrees, it is reduced further to iron metal: The carbon dioxide formed in this process is re-reduced to carbon monoxide by the coke : The temperature-dependent equilibrium controlling the gas atmosphere in the furnace is called the Boudouard reaction : The pig iron produced by the blast furnace has a relatively high carbon content of around 4–5% and usually contains too much sulphur, making it very brittle, and of limited immediate commercial use. Some pig iron

4140-461: The base metal ore. For example, aluminum smelters typically generate fluoride , benzo(a)pyrene , antimony and nickel, as well as aluminum. Copper smelters typically discharge cadmium, lead, zinc , arsenic and nickel, in addition to copper. Lead smelters may discharge antimony , asbestos, cadmium, copper and zinc, in addition to lead. Labourers working in the smelting industry have reported respiratory illnesses inhibiting their ability to perform

4230-432: The blast furnace, such as the Swedish electric blast furnace, have been developed in countries which have no native coal resources. According to Global Energy Monitor , the blast furnace is likely to become obsolete to meet climate change objectives of reducing carbon dioxide emission, but BHP disagrees. An alternative process involving direct reduced iron (DRI) is likely to succeed it, but this also needs to use

4320-479: The bloomery. In areas where quality was important, such as warfare, wrought iron and steel were preferred. Nearly all Han period weapons are made of wrought iron or steel, with the exception of axe-heads, of which many are made of cast iron. Blast furnaces were also later used to produce gunpowder weapons such as cast iron bomb shells and cast iron cannons during the Song dynasty . The simplest forge , known as

4410-578: The bottom, and waste gases ( flue gas ) exiting from the top of the furnace. The downward flow of the ore along with the flux in contact with an upflow of hot, carbon monoxide -rich combustion gases is a countercurrent exchange and chemical reaction process. In contrast, air furnaces (such as reverberatory furnaces ) are naturally aspirated, usually by the convection of hot gases in a chimney flue . According to this broad definition, bloomeries for iron, blowing houses for tin , and smelt mills for lead would be classified as blast furnaces. However,

4500-434: The combustion air ( hot blast ), patented by Scottish inventor James Beaumont Neilson in 1828. Archaeological evidence shows that bloomeries appeared in China around 800 BC. Originally it was thought that the Chinese started casting iron right from the beginning, but this theory has since been debunked by the discovery of 'more than ten' iron digging implements found in the tomb of Duke Jing of Qin (d. 537 BC), whose tomb

4590-424: The combustion zone (1,773–1,873 K (1,500–1,600 °C; 2,732–2,912 °F)). Blast furnaces are currently rarely used in copper smelting, but modern lead smelting blast furnaces are much shorter than iron blast furnaces and are rectangular in shape. Modern lead blast furnaces are constructed using water-cooled steel or copper jackets for the walls, and have no refractory linings in the side walls. The base of

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4680-408: The discovery happened several millennia before the invention of writing, there is no written record of how it was made. However, tin and lead can be smelted by placing the ores in a wood fire, leaving the possibility that the discovery may have occurred by accident. Recent scholarship however has called this find into question. Lead is a common metal, but its discovery had relatively little impact in

4770-513: The establishment of trade networks that spanned large areas of Europe and Asia and had a major effect on the distribution of wealth among individuals and nations. The earliest known cast lead beads were thought to be in the Çatalhöyük site in Anatolia ( Turkey ), and dated from about 6500 BC. However, recent research has discovered that this was not lead, but rather cerussite and galena, minerals rich in, but distinct from, lead. Since

4860-410: The first being that preheated air blown into the furnace reacts with the carbon in the form of coke to produce carbon monoxide and heat: Hot carbon monoxide is the reducing agent for the iron ore and reacts with the iron oxide to produce molten iron and carbon dioxide . Depending on the temperature in the different parts of the furnace (warmest at the bottom) the iron is reduced in several steps. At

4950-429: The first step of smelting: forming two liquids, one an oxide slag containing most of the impurities, and the other a sulfide matte containing the valuable metal sulfide and some impurities. Such "reverb" furnaces are today about 40 meters long, 3 meters high, and 10 meters wide. Fuel is burned at one end to melt the dry sulfide concentrates (usually after partial roasting) which are fed through openings in

5040-454: The first-century .) in northwest Tanzania , based on complex preheating principles. These discoveries are significant for the history of metallurgy. Most early processes in Europe and Africa involved smelting iron ore in a bloomery , where the temperature is kept low enough so that the iron does not melt. This produces a spongy mass of iron called a bloom, which then must be consolidated with

5130-478: The furnace has a chair shape with the lower part of the shaft being narrower than the upper. The lower row of tuyeres being located in the narrow part of the shaft. This allows the upper part of the shaft to be wider than the standard. The blast furnaces used in the Imperial Smelting Process ("ISP") were developed from the standard lead blast furnace, but are fully sealed. This is because

5220-472: The furnace is a hearth of refractory material (bricks or castable refractory). Lead blast furnaces are often open-topped rather than having the charging bell used 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 a double row of tuyeres rather than the single row normally used. The lower shaft of

5310-474: The furnace next to it into which the waste gas (containing CO) from the furnace was directed and burnt. The resultant heat was used to preheat the air blown into the furnace. Hot blast enabled the use of raw anthracite coal, which was difficult to light, in the blast furnace. Anthracite was first tried successfully by George Crane at Ynyscedwyn Ironworks in south Wales in 1837. It was taken up in America by

5400-481: The furnace. Competition in industry drives higher production rates. The largest blast furnace in the world is in South Korea, with a volume around 6,000 m (210,000 cu ft). It can produce around 5,650,000 tonnes (5,560,000 LT) of iron per year. This is a great increase from the typical 18th-century furnaces, which averaged about 360 tonnes (350 long tons; 400 short tons) per year. Variations of

5490-694: The increased demand for iron for casting cannons, the blast furnace came into widespread use in France in the mid 15th century. The direct ancestor of those used in France and England was in the Namur region, in what is now Wallonia (Belgium). From there, they spread first to the Pays de Bray on the eastern boundary of Normandy and from there to the Weald of Sussex , where the first furnace (called Queenstock) in Buxted

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5580-400: The iron's quality. Coke's impurities were more of a problem before hot blast reduced the amount of coke required and before furnace temperatures were hot enough to make slag from limestone free flowing. (Limestone ties up sulphur. Manganese may also be added to tie up sulphur.) Coke iron was initially only used for foundry work, making pots and other cast iron goods. Foundry work was

5670-454: The leather bellows, which wore out quickly. Isaac was granted a second patent, also for blowing cylinders, in 1757. The steam engine and cast iron blowing cylinder led to a large increase in British iron production in the late 18th century. Hot blast was the single most important advance in fuel efficiency of the blast furnace and was one of the most important technologies developed during

5760-408: The material they received. Other buildings on the site included an office and laboratory heated by exhaust steam, a warehouse, two 150 ton railroad track scales. The smelter's office still remains on the site and is now a private residence. Foundations and concrete columns are still visible. The property is privately owned. Copper smelting Smelting is a process of applying heat and

5850-535: The molten iron was tapped twice a day into water, thereby granulating it. The General Chapter of the Cistercian monks spread some technological advances across Europe. This may have included the blast furnace, as the Cistercians are known to have been skilled metallurgists . According to Jean Gimpel, their high level of industrial technology facilitated the diffusion of new techniques: "Every monastery had

5940-722: The oldest evidence, now appears to be hammered, native copper. Combining copper with tin and/or arsenic in the right proportions produces bronze , an alloy that is significantly harder than copper. The first copper/arsenic bronzes date from 4200 BC from Asia Minor . The Inca bronze alloys were also of this type. Arsenic is often an impurity in copper ores, so the discovery could have been made by accident. Eventually, arsenic-bearing minerals were intentionally added during smelting. Copper–tin bronzes, harder and more durable, were developed around 3500 BC, also in Asia Minor. How smiths learned to produce copper/tin bronzes

6030-455: The ore and liberating the sulfur as sulfur dioxide gas. Smelting most prominently takes place in a blast furnace to produce pig iron , which is converted into steel . Plants for the electrolytic reduction of aluminium are referred to as aluminium smelters . Smelting involves more than just melting the metal out of its ore. Most ores are the chemical compound of the metal and other elements, such as oxygen (as an oxide ), sulfur (as

6120-430: The ore binds to carbon at high temperatures, as the chemical potential energy of the bonds in carbon dioxide (CO 2 ) is lower than that of the bonds in the ore. Sulfide ores such as those commonly used to obtain copper, zinc or lead, are roasted before smelting in order to convert the sulfides to oxides, which are more readily reduced to the metal. Roasting heats the ore in the presence of oxygen from air, oxidizing

6210-464: The ore during smelting to catalyze the desired reactions and to chemically bind to unwanted impurities or reaction products. Calcium carbonate or calcium oxide in the form of lime are often used for this purpose, since they react with sulfur, phosphorus, and silicon impurities to allow them to be readily separated and discarded, in the form of slag. Fluxes may also serve to control the viscosity and neutralize unwanted acids. Flux and slag can provide

6300-400: The ore, yielding the purified metal element as a product. The carbon source is oxidized in two stages. First, carbon (C) combusts with oxygen (O 2 ) in the air to produce carbon monoxide (CO). Second, the carbon monoxide reacts with the ore (e.g. Fe 2 O 3 ) and removes one of its oxygen atoms, releasing carbon dioxide (CO 2 ). After successive interactions with carbon monoxide, all of

6390-431: The oxygen in the ore will be removed, leaving the raw metal element (e.g. Fe). As most ores are impure, it is often necessary to use flux , such as limestone (or dolomite ), to remove the accompanying rock gangue as slag. This calcination reaction emits carbon dioxide. The required temperature varies both in absolute terms and in terms of the melting point of the base metal. Examples: Fluxes are materials added to

6480-399: The particle size of the coke or charcoal is of great relevance. Therefore, the coke must be strong enough so it will not be crushed by the weight of the material above it. Besides the physical strength of its particles, the coke must also be low in sulfur, phosphorus , and ash. The main chemical reaction producing the molten iron is: This reaction might be divided into multiple steps, with

6570-600: The physical tasks demanded by their jobs. In the United States, the Environmental Protection Agency has published pollution control regulations for smelters. 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

6660-457: The pig iron. It reacts with calcium oxide (burned limestone) and forms silicates, which float to the surface of the molten pig iron as slag. Historically, to prevent contamination from sulfur, the best quality iron was produced with charcoal. In a blast furnace, a downward-moving column of ore, flux, coke (or charcoal ) and their reaction products must be sufficiently porous for the flue gas to pass through, upwards. To ensure this permeability

6750-404: The principle of chemical reduction whereby carbon monoxide converts iron oxides to elemental iron. Blast furnaces differ from bloomeries and reverberatory furnaces in that in a blast furnace, flue gas is in direct contact with the ore and iron, allowing carbon monoxide to diffuse into the ore and reduce the iron oxide. The blast furnace operates as a countercurrent exchange process whereas

6840-419: The reaction zone. As the material travels downward, the counter-current gases both preheat the feed charge and decompose the limestone to calcium oxide and carbon dioxide: The calcium oxide formed by decomposition reacts with various acidic impurities in the iron (notably silica ), to form a fayalitic slag which is essentially calcium silicate , Ca Si O 3 : As the iron(II) oxide moves down to

6930-401: The roof of the furnace. The slag floats over the heavier matte and is removed and discarded or recycled. The sulfide matte is then sent to the converter . The precise details of the process vary from one furnace to another depending on the mineralogy of the ore body. While reverberatory furnaces produced slags containing very little copper, they were relatively energy inefficient and off-gassed

7020-447: The second stage include fining in a finery forge . In the 13th century during the High Middle Ages the blast furnace was introduced by China who had been using it since as early as 200 b.c during the Qin dynasty . [1] Puddling was also introduced in the Industrial Revolution . Both processes are now obsolete, and wrought iron is now rarely made. Instead, mild steel is produced from

7110-479: The structure of horse powered reciprocators that already existed. That is, the circular motion of the wheel, be it horse driven or water driven, was transferred by the combination of a belt drive , a crank-and-connecting-rod, other connecting rods , and various shafts, into the reciprocal motion necessary to operate a push bellow. Donald Wagner suggests that early blast furnace and cast iron production evolved from furnaces used to melt bronze . Certainly, though, iron

7200-651: The temperature needed, so some propose that the first smelting of copper may have occurred in pottery kilns . (The development of copper smelting in the Andes, which is believed to have occurred independently of the Old World , may have occurred in the same way. ) The earliest current evidence of copper smelting, dating from between 5500 BC and 5000 BC, has been found in Pločnik and Belovode, Serbia. A mace head found in Turkey and dated to 5000 BC, once thought to be

7290-458: The term has usually been limited to those used for smelting iron ore to produce pig iron , an intermediate material used in the production of commercial iron and steel , and the shaft furnaces used in combination with sinter plants in base metals smelting. Blast furnaces are estimated to have been responsible for over 4% of global greenhouse gas emissions between 1900 and 2015, but are difficult to decarbonize. Blast furnaces operate on

7380-427: The top, where the temperature usually is in the range between 200 °C and 700 °C, the iron oxide is partially reduced to iron(II,III) oxide, Fe 3 O 4 . The temperatures 850 °C, further down in the furnace, the iron(II,III) is reduced further to iron(II) oxide: Hot carbon dioxide, unreacted carbon monoxide, and nitrogen from the air pass up through the furnace as fresh feed material travels down into

7470-774: The world charcoal was cheaper while coke was more expensive even after the Industrial Revolution: e. g., in the US charcoal-fueled iron production fell in share to about a half ca. 1850 but still continued to increase in absolute terms until ca. 1890, while in João Monlevade in the Brazilian Highlands charcoal-fired blast furnaces were built as late as the 1930s and only phased out in 2000. Darby's original blast furnace has been archaeologically excavated and can be seen in situ at Coalbrookdale, part of

7560-586: The zinc produced by these furnaces is recovered as metal from the vapor phase, and the presence of oxygen in the off-gas would result in the formation of zinc oxide. Blast furnaces used in the ISP have a more intense operation than standard lead blast furnaces, with higher air blast rates per m of hearth area and a higher coke consumption. Zinc production with the ISP is more expensive than with electrolytic zinc plants, so several smelters operating this technology have closed in recent years. However, ISP furnaces have

7650-532: Was built in about 1491, followed by one at Newbridge in Ashdown Forest in 1496. They remained few in number until about 1530 but many were built in the following decades in the Weald, where the iron industry perhaps reached its peak about 1590. Most of the pig iron from these furnaces was taken to finery forges for the production of bar iron . The first British furnaces outside the Weald appeared during

7740-477: Was essential to military success by the time the State of Qin had unified China (221 BC). Usage of the blast and cupola furnace remained widespread during the Song and Tang dynasties . By the 11th century, the Song dynasty Chinese iron industry made a switch of resources from charcoal to coke in casting iron and steel, sparing thousands of acres of woodland from felling. This may have happened as early as

7830-476: Was its lower cost, mainly because making coke required much less labor than cutting trees and making charcoal, but using coke also overcame localized shortages of wood, especially in Britain and eleswhere in Europe. Metallurgical grade coke will bear heavier weight than charcoal, allowing larger furnaces. A disadvantage is that coke contains more impurities than charcoal, with sulfur being especially detrimental to

7920-1041: Was one of the largest point sources of mercury in North America in the 20th century. Even after smelter releases were drastically reduced, landscape re-emission continued to be a major regional source of mercury. Lakes will likely receive mercury contamination from the smelter for decades, from both re-emissions returning as rainwater and leaching of metals from the soil. Air pollutants generated by aluminium smelters include carbonyl sulfide , hydrogen fluoride , polycyclic compounds , lead, nickel , manganese , polychlorinated biphenyls , and mercury . Copper smelter emissions include arsenic, beryllium , cadmium , chromium , lead, manganese, and nickel. Lead smelters typically emit arsenic, antimony , cadmium and various lead compounds. Wastewater pollutants discharged by iron and steel mills includes gasification products such as benzene , naphthalene , anthracene , cyanide , ammonia , phenols and cresols , together with

8010-646: Was probably being consumed as fast as the wood to make it grew. The first blast furnace in Russia opened in 1637 near Tula and was called the Gorodishche Works. The blast furnace spread from there to central Russia and then finally to the Urals . In 1709, at Coalbrookdale in Shropshire, England, Abraham Darby began to fuel a blast furnace with coke instead of charcoal . Coke's initial advantage

8100-526: Was the material of choice for weapons such as swords , daggers , battle axes , and spear and arrow points, as well as protective gear such as shields , helmets , greaves (metal shin guards), and other body armor . Bronze also supplanted stone, wood, and organic materials in tools and household utensils—such as chisels , saws , adzes , nails , blade shears , knives , sewing needles and pins , jugs , cooking pots and cauldrons , mirrors , and horse harnesses . Tin and copper also contributed to

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