A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.
In 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 the bottom, and waste gases (flue gas) exiting from the top of the furnace. The downward flow of the ore and 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, 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.
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 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 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 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 the 5th century BC, employing workforces of over 200 men in iron smelters from the 3rd century onward, the earliest extant blast furnaces were built date 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 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 blast furnace 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. Donald Wagner suggests that early blast furnace and cast iron production evolved from furnaces used to melt bronze. Certainly, though, iron 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 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 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.
The simplest forge, known as the Corsican, was used prior to the advent of Christianity. Examples of improved bloomeries are the Stückofen (sometimes called wolf-furnace) or the Catalan forge, which remained until the beginning of the 19th century. The Catalan forge was invented in Catalonia, Spain, during the 8th 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 airstream in with bellows is known as cold blast, and it increases the fuel efficiency of the bloomery and improves yield. The Catalan forges can also be built bigger than natural draught bloomeries.
The oldest known blast furnaces in the West were built in Dürstel 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, there have also been found traces of blast furnaces dated even earlier, possibly to around 1100. These early blast furnaces, like 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 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 is possible that the technology reached Sweden by this means. High quality ores, water power for bellows for blast and wood for charcoal are readily obtainable in Sweden. However, since blast furnace technology was independently invented in Africa by the Haya people, it is more likely that the process was invented independently in Scandinavia. The step from bloomery to true blast furnace is not big. Simply just building a bigger furnace and using bigger bellows to increase the volume of the blast and hence the amount of oxygen leads inevitably into higher temperatures, bloom melting into liquid iron and, cast iron flowing from the smelters. Already the Vikings are known to have used double bellows, which greatly increases the volumetric flow of the blast.
This Caspian region may also separately be the technological source for at furnace at Ferriere, described by Filarete. Water-powered bellows at Semogo in northern Italy in 1226 in a two-stage process. In this, the molten iron was tapped twice a day into water thereby granulating it.
One means by which certain technological advances were transmitted within Europe was a result of the General Chapter of the Cistercian monks. 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 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 within time surpluses were being offered for sale. The Cistercians became the leading iron producers in Champagne, France, from the mid-13th century to 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 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.
The direct ancestor of these 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 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 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 was probably being consumed as fast as the wood to make it grew. The Backbarrow blast furnace built in Cumbria in 1711 has been described as the first efficient example.
In 1709, at Coalbrookdale in Shropshire, England, Abraham Darby began to fuel a blast furnace with coke instead of charcoal. Coke's initial advantage 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 on the Continent. 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 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 sulfur. Manganese may also be added to tie up sulfur).:123–125:122–23
Coke iron was initially only used for foundry work, making pots and other cast iron goods. Foundry work was 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. Darby's original blast furnace has been archaeologically excavated and can be seen in situ at Coalbrookdale, part of the Ironbridge Gorge Museums. Cast iron from the furnace was used to make girders for the world's first 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. The cast iron blowing cylinder was developed in 1768 to replace the leather bellows, which wore out quickly. 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 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 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, to 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 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 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 m3 (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 the blast furnace, such as the Swedish electric blast furnace, have been developed in countries which have no native coal resources.
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. The overall shaft height is around 5 to 6 m. 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 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 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 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 m2 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 the advantage of being able to treat zinc concentrates containing higher levels of lead than can electrolytic zinc plants.
Modern furnaces are equipped with an array of supporting facilities to increase efficiency, such as ore storage yards where barges are unloaded. The raw materials are transferred to the stockhouse complex by ore bridges, or rail hoppers and ore transfer cars. Rail-mounted scale cars or computer controlled weight hoppers weigh out the various raw materials to yield the desired hot metal and slag chemistry. The raw materials are brought to the top of the blast furnace via a skip car powered by winches or conveyor belts.
There are different ways in which the raw materials are charged into the blast furnace. Some blast furnaces use a "double bell" system where two "bells" are used to control the entry of raw material into the blast furnace. The purpose of the two bells is to minimize the loss of hot gases in the blast furnace. First, the raw materials are emptied into the upper or small bell which then opens to empty the charge into the large bell. The small bell then closes, to seal the blast furnace, while the large bell rotates to provide specific distribution of materials before dispensing the charge into the blast furnace. A more recent design is to use a "bell-less" system. These systems use multiple hoppers to contain each raw material, which is then discharged into the blast furnace through valves. These valves are more accurate at controlling how much of each constituent is added, as compared to the skip or conveyor system, thereby increasing the efficiency of the furnace. Some of these bell-less systems also implement a discharge chute in the throat of the furnace (as with the Paul Wurth top) in order to precisely control where the charge is placed.
The iron making blast furnace itself is built in the form of a tall structure, lined with refractory brick, and profiled to allow for expansion of the charged materials as they heat during their descent, and subsequent reduction in size as melting starts to occur. Coke, limestone flux, and iron ore (iron oxide) are charged into the top of the furnace in a precise filling order which helps control gas flow and the chemical reactions inside the furnace. Four "uptakes" allow the hot, dirty gas high in carbon monoxide content to exit the furnace throat, while "bleeder valves" protect the top of the furnace from sudden gas pressure surges. The coarse particles in the exhaust gas settle in the "dust catcher" and are dumped into a railroad car or truck for disposal, while the gas itself flows through a venturi scrubber and/or electrostatic precipitators and a gas cooler to reduce the temperature of the cleaned gas.
The "casthouse" at the bottom half of the furnace contains the bustle pipe, water cooled copper tuyeres and the equipment for casting the liquid iron and slag. Once a "taphole" is drilled through the refractory clay plug, liquid iron and slag flow down a trough through a "skimmer" opening, separating the iron and slag. Modern, larger blast furnaces may have as many as four tapholes and two casthouses. Once the pig iron and slag has been tapped, the taphole is again plugged with refractory clay.
The tuyeres are used to implement a hot blast, which is used to increase the efficiency of the blast furnace. The hot blast is directed into the furnace through water-cooled copper nozzles called tuyeres near the base. The hot blast temperature can be from 900 °C to 1300 °C (1600 °F to 2300 °F) depending on the stove design and condition. The temperatures they deal with may be 2000 °C to 2300 °C (3600 °F to 4200 °F). Oil, tar, natural gas, powdered coal and oxygen can also be injected into the furnace at tuyere level to combine with the coke to release additional energy and increase the percentage of reducing gases present which is necessary to increase productivity.
Blast furnaces operate on the principle of chemical reduction whereby carbon monoxide, having a stronger affinity for the oxygen in iron ore than iron does, reduces the iron to its elemental form. 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 to elemental iron mixed with carbon. The blast furnaces operates as a countercurrent exchange process whereas a bloomery does not. Another difference is that bloomeries operate as a batch process while blast furnaces operate continuously for long periods because they are difficult to start up and shut down. (See: Continuous production) 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 the pig iron. It reacts with calcium oxide (burned limestone) and forms a silicate which floats to the surface of the molten pig iron as "slag". Historically, to prevent contamination from sulfur, the best quality iron was produced with charcoal.
The downward moving column of ore, flux, coke or charcoal and reaction products must be porous enough for the flue gas to pass through. This requires the coke or charcoal to be in large enough particles to be permeable, meaning there cannot be an excess of fine particles. Therefore, the coke must be strong enough so it will not be crushed by the weight of the material above it. Besides physical strength of the coke, it must also be low in sulfur, phosphorus, and ash. This necessitates the use of metallurgical coal, which is a premium grade due to its relative scarcity.
The main chemical reaction producing the molten iron is:
This reaction might be divided into multiple steps, with the first being that preheated blast air blown into the furnace reacts with the carbon in the form of coke to produce carbon monoxide and heat:
The 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 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, Fe3O4.
At temperatures around 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 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:
As the iron(II) oxide moves down to 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%, making it very brittle, and of limited immediate commercial use. Some pig iron is used to make cast iron. The majority of pig iron produced by blast furnaces undergoes further processing to reduce the carbon content and produce various grades of steel used for construction materials, automobiles, ships and machinery.
Although the efficiency of blast furnaces is constantly evolving, the chemical process inside the blast furnace remains the same. According to the American Iron and Steel Institute: "Blast furnaces will survive into the next millennium because the larger, efficient furnaces can produce hot metal at costs competitive with other iron making technologies." One of the biggest drawbacks of the blast furnaces is the inevitable carbon dioxide production as iron is reduced from iron oxides by carbon and as of 2016, there is no economical substitute – steelmaking is one of the largest industrial contributors of the CO2 emissions in the world (see greenhouse gases).
The challenge set by the greenhouse gas emissions of the blast furnace is being addressed in an ongoing European Program called ULCOS (Ultra Low CO2 Steelmaking). Several new process routes have been proposed and investigated in depth to cut specific emissions (CO
2 per ton of steel) by at least 50%. Some rely on the capture and further storage (CCS) of CO
2, while others choose decarbonizing iron and steel production, by turning to hydrogen, electricity and biomass. In the nearer term, a technology that incorporates CCS into the blast furnace process itself and is called the Top-Gas Recycling Blast Furnace is under development, with a scale-up to a commercial size blast furnace under way. The technology should be fully demonstrated by the end of the 2010s, in line with the timeline set, for example, by the EU to cut emissions significantly. Broad deployment could take place from 2020 on.
Stone wool or rock wool is a spun mineral fibre used as an insulation product and in hydroponics. It is manufactured in a blast furnace fed with diabase rock which contains very low levels of metal oxides. The resultant slag is drawn off and spun to form the rock wool product. Very small amounts of metals are also produced which are an unwanted by-product and run to waste.
For a long time, it was normal procedure for a decommissioned blast furnace to be demolished and either be replaced with a newer, improved one, or to have the entire site demolished to make room for follow-up use of the area. In recent decades, several countries have realized the value of blast furnaces as a part of their industrial history. Rather than being demolished, abandoned steel mills were turned into museums or integrated into multi-purpose parks. The largest number of preserved historic blast furnaces exists in Germany; other such sites exist in Spain, France, the Czech Republic, Japan, Luxembourg, Poland, Romania, Mexico, Russia and the United States.
The blast furnace gas can be used to generate heat. So by reducing the constituents in blast furnace gas we can increase the calorific value and can be used to generate heat and rise the temperature in any furnace.
The gas cleaning system contains two stages, the coarse cleaning system and the fine cleaning system.
In the coarse cleaning system a dust catcher is used. A dust catcher is a cylindrical steel structure with conical top and bottom sections. It is also lined with refractory bricks.
The principle of the dust catcher is that the dust-laden gas is given a sudden reverse in speed and direction. Because of their mass, the coarse dust particles cannot change their velocity easily, and hence settle to the bottom.
...earliest blast furnace discovered in China from about the first century AD
Blast furnace gas (BFG) is a by-product of blast furnaces that is generated when the iron ore is reduced with coke to metallic iron. It has a very low heating value, about 93 BTU/cubic foot (3.5 MJ/m3), because it consists of about 60 percent nitrogen and 18-20% carbon dioxide, which are not flammable. The rest is mostly carbon monoxide, which has a fairly low heating value already and some (2-4%) hydrogen. It is commonly used as a fuel within the steel works, but it can be used in boilers and power plants equipped to burn it. It may be combined with natural gas or coke oven gas before combustion or a flame support with richer gas or oil is provided to sustain combustion. Particulate matter is removed so that it can be burned more cleanly. Blast furnace gas is sometimes flared without generating heat or electricity.
Blast furnace gas is generated at higher pressure and at about 100–150 °C (212–302 °F) in a modern blast furnace. This pressure is utilized to operate a generator (Top-gas-pressure Recovery Turbine - i.e. TRT in short), which can generate electrical energy up to 35 kWh/t of pig iron without burning any fuel. Dry type TRTs can generate more power than wet type TRT.
Auto ignition point of blast furnace gas is approximate 630–650 °C (1,166–1,202 °F) and it has LEL (Lower Explosive Limit) of 27% & UEL (Upper Explosive Limit) of 75% in an air-gas mixture at normal temperature and pressure.
The high concentration of carbon monoxide makes the gas hazardous.Bloomery
A bloomery is a type of furnace once used widely for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. A bloomery's product is a porous mass of iron and slag called a bloom. This mix of slag and iron in the bloom is termed sponge iron, which is usually consolidated and further forged into wrought iron. The bloomery has now largely been superseded by the blast furnace, which produces pig iron.Cornwall Iron Furnace
Cornwall Iron Furnace is a designated National Historic Landmark that is administered by the Pennsylvania Historical and Museum Commission in Cornwall, Lebanon County, Pennsylvania in the United States. The furnace was a leading Pennsylvania iron producer from 1742 until it was shut down in 1883. The furnaces, support buildings and surrounding community have been preserved as a historical site and museum, providing a glimpse into Lebanon County's industrial past. The site is the only intact charcoal-burning iron blast furnace in its original plantation in the western hemisphere. Established by Peter Grubb in 1742, Cornwall Furnace was operated during the Revolution by his sons Curtis and Peter Jr. who were major arms providers to George Washington. Robert Coleman acquired Cornwall Furnace after the Revolution and became Pennsylvania's first millionaire. Ownership of the furnace and its surroundings was transferred to the Commonwealth of Pennsylvania in 1932.Du Shi
Du Shi (Chinese: 杜詩; pinyin: Dù Shī; Wade–Giles: Tu Shih, d. 38) was a Chinese politician and mechanical engineer of the Eastern Han Dynasty in ancient China. Du Shi is credited with being the first to apply hydraulic power (i.e. a waterwheel) to operate bellows (air-blowing device) in metallurgy. His invention was used to operate piston-bellows of the blast furnace and then cupola furnace in order to forge cast iron, which had been known in China since the 6th century BC. He worked as a censorial officer and administrator of several places during the reign of Emperor Guangwu of Han. He also led a brief military campaign in which he eliminated a small bandit army under Yang Yi (d. 26).FINEX (steelmaking process)
FINEX is the name for an iron making technology developed by Siemens VAI and POSCO. Molten iron is produced directly using iron ore fines and non-coking coal rather than traditional blast furnace methods through sintering and reduction with coke. Elimination of preliminary processing is claimed to make the plant for FINEX less expensive to build than a blast furnace facility of the same scale, additionally a 10-15% reduction in production costs is expected/claimed through cheaper raw materials, reduction of facility cost, pollutant exhaustion, maintenance staff and production time. The process is claimed to produce less pollutants such as SOx, NOx, and carbon dioxide than traditional methods.This process is essentially a combination of FINMET's Fluidized Bed and COREX's Melter Gasifier, hence its name "FINEX".Govăjdia Blast Furnace
The Govăjdia Blast Furnace is a disused blast furnace in Govăjdia village, Ghelari Commune, Hunedoara County, in the Transylvania region of Romania.
An earlier blast furnace had been set up at Topliţa in 1781, but the quantity of raw materials it prepared for workshops involved in cast iron refining proved inadequate. Thus, the Thesaurariat at Sibiu, which represented the Imperial Austrian authorities, coordinated mining activities in Transylvania and had an office based in the Hunyad Castle, decided in 1802 to build a second furnace in the Hunedoara area. The site chosen was at the confluence of two rivers close to a group of forge works and iron mines. Construction began in 1806, and although finished in 1810, production only began in April 1813, once the necessary annexes had been built. A tablet placed on the front of the furnace read: Augusto Imperante Francisco Extructum 1810 ("Built 1810 during the reign of the venerable Francis").The furnace's first period of use was fairly short at seven and a half months, as the crucible had become quite worn and enough cast iron had been generated to last the nearby workshops three years. In all, 1380.3 tons of cast iron were produced. Periods of repair, use and abandonment followed over the ensuing century. In 1837, a fire caused structural damage to the furnace, and an investment of 40,529 forints was approved. Its volume was expanded to 26.45 m3, the water wheel was repaired and the bellows compressor was improved. On August 25, 1840, an air preheater began operating. In 1841, a narrow gauge railway for transporting ore to the furnace's upper opening was installed. Little wagons would load the ore downward into the furnace; this mechanism replaced the inclined planes used earlier. The railway was 246.8 m long and made of cast iron from Govăjdia, and was the first such of its kind in Transylvania, extended to Hunedoara in 1900 (see Transylvanian mining railway). The cooling systems, the loading mechanism and the continuous production cycle were quite advanced for contemporary Europe. Its most intense period of production took place between 1871 and 1889. Legend holds that metal prepared there as well as at the Reşiţa works was used for raw material in the building of the Eiffel Tower, but there is no documentary evidence in support of this claim. Activity lessened after 1896 due to the new Hunedoara Steel Works. The final repairs were made in 1914–1916, and the last batch of cast iron came out in 1918. The furnace closed down permanently in 1924.In 2008, the site was acquired by Ghelari Town Hall because of a failure by Hunedoara Steel Works, the previous owner, to pay taxes on the property. As of 2010, the chimney was intact with the original iron girdles still in place, but the roof was in serious need of repair, and the site was strewn with garbage, although the interior was fairly clean.Ground granulated blast-furnace slag
Ground-granulated blast-furnace slag (GGBS or GGBFS) is obtained by quenching molten iron slag (a by-product of iron and steel-making) from a blast furnace in water or steam, to produce a glassy, granular product that is then dried and ground into a fine powder.List of preserved historic blast furnaces
This list of preserved historic blast furnaces contains decommissioned blast furnaces, of which substantial remains survive. The furnaces are preserved in a park or museum, or as a site otherwise open to visitors, or intended to become such.
While pre-20th-century blast furnaces already have a long history of monument preservation, the perception of 20th century mass production blast furnace installations as industrial heritage is a comparably new trend. For a long time, it has been normal procedure for such a blast furnace to be demolished after being decommissioned and either be replaced with a newer, improved one, or to have the entire site demolished to make room for follow-up use of the area. It has only been in recent years that numerous countries have realized the value of blast furnaces as a part of their industrial history.Historically, the first such blast furnace not to be demolished stands in Starachowice, Poland (decommissioned in 1968), followed by the last blast furnace of Yahata Steel Works in Yahatahigashi-ku, Kitakyūshū, Japan (decommissioned in 1972) and the "Carrie Furnaces" in Homestead, Pennsylvania in the United States (decommissioned in 1978). One of the two blast furnaces in Neunkirchen in Germany (decommissioned in 1982) was the first blast furnace worldwide to be not just preserved, but actively refurbished for the purpose of preservation.
For 20th-century mass production blast furnaces, the degree of accurate preservation versus integration into new structures, or even re-purposing, differs between the various sites. Colorful illumination installations at night are common.Lithgow Blast Furnace
The Lithgow Blast Furnace is a heritage-listed former blast furnace and now park and visitor attraction at Inch Street, Lithgow, City of Lithgow, New South Wales, Australia. It was built from 1906 to 1907 by William Sandford Limited. It is also known as Eskbank Ironworks Blast Furnace site; Industrial Archaeological Site. The property is owned by Lithgow City Council. It was added to the New South Wales State Heritage Register on 2 April 1999.Maria Furnace, Pennsylvania
Maria Furnace is a South Mountain populated place on Toms Creek west of Fairfield, Pennsylvania, that was the location of an 1822 blast furnace until operations were moved to Caledonia. The remains of the original blast furnace ("Maria Furnace") are located at coordinates: 39|46|30.64 N, 77|24|25.98 W. The remains consist of a pile of rocks in a small wooded area overgrown with vegetation.Nassawango Creek
Nassawango Creek is a stream in the U.S. state of Maryland; it is the largest tributary of the Pocomoke River, located on the Delmarva Peninsula. Older variations on the same name include Nassanongo, Naseongo, Nassiongo, and Nassiungo, meaning "[ground] between [the streams]". Early English records have it as Askimenokonson Creek, after a Native settlement near its headwaters (askimenokonson roughly approximating a local Algonquian word meaning "stony place where they pick early [straw]berries").The Nassawango (locally or ) rises in Wicomico County, Maryland and flows 20.8 miles (33.5 km) through Worcester County to join the Pocomoke below Snow Hill. Large portions of its drainage lie within the Pocomoke River State Forest and The Nature Conservancy's Nassawango Creek Preserve. Nassawango Creek and its tributaries were once dammed in several places for mills; one dam site, became an early industrial blast furnace operation, where bog iron ore was smelted to make pig iron at Furnacetown during the first half of the 19th century. Today, the furnace grounds are considered a local historical landmark.Næs jernverk
Næs Ironworks (Norwegian: Næs Jernverk or Næs verk) in Holt (now part of Tvedestrand municipality, in Aust-Agder county, Norway), was an iron works which started operation in 1665 under the name “Baaseland Værk”. The blast furnace and foundry were located at the Båsland farm, while the associated forge was located a kilometer further east, by the Storelva river at Næs. The blast furnace was new, and not an extension of the Barbu jernverk at Arendal which ceased operations in the 1650s. “Baaseland Værk” was given the name Naes blast furnace operation when the buildings were concentrated by Storelva in 1738.
About 1840 the firm was renamed Jacob Aall & Søn. It ceased operation in 1959.Pig iron
Pig iron is an intermediate product of the iron industry, also known as crude iron, which is first obtained from a smelting furnace in the form of oblong blocks. Pig iron has a very high carbon content, typically 3.8–4.7%, along with silica and other constituents of dross, which makes it very brittle and not useful directly as a material except for limited applications. Pig iron is made by smelting iron ore into a transportable ingot of impure high carbon-content iron in a blast furnace as an ingredient for further processing steps. The traditional shape of the molds used for pig iron ingots was a branching structure formed in sand, with many individual ingots at right angles to a central channel or runner, resembling a litter of piglets being suckled by a sow. When the metal had cooled and hardened, the smaller ingots (the pigs) were simply broken from the runner (the sow), hence the name pig iron. As pig iron is intended for remelting, the uneven size of the ingots and the inclusion of small amounts of sand caused only insignificant problems considering the ease of casting and handling them.Reverberatory furnace
A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases. The term reverberation is used here in a generic sense of rebounding or reflecting, not in the acoustic sense of echoing.Rock Forge, West Virginia
Rock Forge is an unincorporated community in Monongalia County, West Virginia.
Rock Forge had its start in 1796 when a blast furnace opened at the site.Slag
Slag is the glass-like by-product left over after a desired metal has been separated (i.e., smelted) from its raw ore. Slag is usually a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and elemental metals. While slags are generally used to remove waste in metal smelting, they can also serve other purposes, such as assisting in the temperature control of the smelting, and minimizing any re-oxidation of the final liquid metal product before the molten metal is removed from the furnace and used to make solid metal. In some smelting processes, such as ilmenite smelting to produce titanium dioxide, the slag is the valuable product instead of the metal.Steel mill
A steel mill or steelworks is an industrial plant for the manufacture of steel. It may be an integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled product, but may also describe plants where steel semi-finished casting products (blooms, ingots, slabs, billets) are made, from molten pig iron or from scrap.Steelmaking
Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon(most important impurity) are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon and vanadium are added to produce different grades of steel. Limiting dissolved gases such as nitrogen and oxygen and entrained impurities (termed "inclusions") in the steel is also important to ensure the quality of the products cast from the liquid steel.Steelmaking has existed for millennia, but it was not commercialized on a massive scale until late 19th century. The ancient craft process of steelmaking was the crucible process. In the 1850s and 1860s, the Bessemer process and the Siemens-Martin process turned steelmaking into a heavy industry. Today there are two major commercial processes for making steel, namely basic oxygen steelmaking, which has liquid pig-iron from the blast furnace and scrap steel as the main feed materials, and electric arc furnace (EAF) steelmaking, which uses scrap steel or direct reduced iron (DRI) as the main feed materials. Oxygen steelmaking is fuelled predominantly by the exothermic nature of the reactions inside the vessel; in contrast, in EAF steelmaking, electrical energy is used to melt the solid scrap and/or DRI materials. In recent times, EAF steelmaking technology has evolved closer to oxygen steelmaking as more chemical energy is introduced into the process.Texas and Northern Railway
The Texas and Northern Railway (reporting mark TN) is an eight-mile (13 km) railroad connecting Lone Star, Texas, to the former Louisiana and Arkansas Railway at Cason between Daingerfield and Hughes Springs.
A number of branches have been removed over the years as mining of ore is no longer done. The blast furnace was shut down in the 1980s as well as the ore smelter. Only the electric blast furnace and the pipe rolling mill are still in operation along with warehouse facilities.
Operations have been cut back, and since Lone Star was purchased by U.S. Steel, the railroad is managed under that company's railroad division, Transtar, Inc.
Traffic consists of outbound pipe, and inbound scrap steel and alloy steel ingots.
For years the railroad bought secondhand ALCO diesel locomotives and heavily modified them for their and the steel mill railroad operations.
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