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Blast furnace

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FormerAHMblast furnace in Port of Sagunt,Valencia,Spain

Ablast furnaceis a type ofmetallurgical furnaceused forsmeltingto produce industrial metals, generallypig iron,but also others such asleadorcopper.Blastrefers to the combustion air being supplied aboveatmospheric pressure.[1]

In a blast furnace, fuel (coke),ores,andflux(limestone) are continuously supplied through the top of the furnace, while a hot blast ofair(sometimes withoxygenenrichment) is blown into the lower section of the furnace through a series of pipes calledtuyeres,so that thechemical reactionstake place throughout the furnace as the material falls downward. The end products are usually molten metal andslagphases tapped from the bottom, and waste gases (flue gas) exiting from the top of the furnace.[2]The downward flow of the ore along with the flux in contact with an upflow of hot,carbon monoxide-rich combustion gases is acountercurrent exchangeand chemical reaction process.[3]

In contrast, air furnaces (such asreverberatory furnaces) are naturally aspirated, usually by theconvectionof hot gases in achimney flue.According to this broad definition,bloomeriesfor iron,blowing housesfortin,andsmelt millsforleadwould be classified as blast furnaces. However, the term has usually been limited to those used for smeltingiron oreto producepig iron,an intermediate material used in the production of commercial iron andsteel,and the shaft furnaces used in combination withsinter plantsinbase metalssmelting.[4][5]

Blast furnaces are estimated to have been responsible for over 4% of globalgreenhouse gas emissionsbetween 1900 and 2015, but are difficult to decarbonize.[6]

Process engineering and chemistry[edit]

Blast furnaces ofTřinec Iron and Steel WorksinCzech Republic
Charcoal burning iron blast furnace inJackson County, Ohio,1923
Risingcarbon monoxidereducesiron oxidesto pureironthrough a series of reactions that occur at different areas within a blast furnace.

Blast furnaces operate on the principle ofchemical reductionwhereby carbon monoxide converts iron oxides to elemental iron. Blast furnaces differ frombloomeriesandreverberatory furnacesin 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 acountercurrent exchangeprocess whereas a bloomery does not. Another difference is that bloomeries operate as a batch process whereas blast furnacesoperate continuouslyfor 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.

Silicahas to be removed from the pig iron. It reacts withcalcium 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.

The downward moving column of ore, flux,cokeor charcoal and reaction products must be sufficiently porous for the flue gas to pass through. To ensure this permeability 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.[7]

The main chemical reaction producing the molten iron is:

Fe2O3+ 3CO → 2Fe + 3CO2[8]

This reaction might be divided into multiple steps, with the first being that preheated air blown into the furnace reacts with the carbon in the form of coke to producecarbon monoxideand heat:

2 C(s)+ O2(g)→ 2 CO(g)[9]

The hot carbon monoxide is the reducing agent for the iron ore and reacts with theiron oxideto produce molten iron andcarbon 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.

3 Fe2O3(s)+ CO(g)→ 2 Fe3O4(s)+ CO2(g)[9]

The temperatures 850 °C, further down in the furnace, the iron(II,III) is reduced further to iron(II) oxide:

Fe3O4(s)+ CO(g)→ 3 FeO(s)+ CO2(g)[9]

Hot carbon dioxide, unreacted carbon monoxide, andnitrogenfrom 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 tocalcium oxideand carbon dioxide:

CaCO3(s)→ CaO(s)+ CO2(g)[9]

The calcium oxide formed by decomposition reacts with various acidic impurities in the iron (notablysilica), to form afayaliticslag which is essentiallycalcium silicate,CaSiO
3:[8]

SiO2+ CaO → CaSiO3[10][11]

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:

FeO(s)+ CO(g)→ Fe(s)+ CO2(g)[9]

The carbon dioxide formed in this process is re-reduced to carbon monoxide by thecoke:

C(s)+ CO2(g)→ 2 CO(g)[9]

The temperature-dependent equilibrium controlling the gas atmosphere in the furnace is called theBoudouard reaction:

2CO ⇌ CO2+ C

Thepig ironproduced 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 is used to makecast 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 addingcalcium oxide,which reacts with theiron sulfidecontained in the pig iron to formcalcium sulfide(calledlime desulfurization).[12]In a further process step, the so-calledbasic oxygen steelmaking,the carbon is oxidized by blowing oxygen onto the liquid pig iron to formcrude steel.

Although the efficiency of blast furnaces is constantly evolving, the chemical process inside the blast furnace remains the same. 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 CO2emissions in the world (seegreenhouse gases).[13]Several alternatives are being investigated such asplastic waste,biomass or hydrogen as reducing agent, which can substantially reduce the carbon emissions.[14]The injection of, for example, hydrogen into blast furnaces can reduce carbon emissions by 20 percent.[15]

The challenge set by the greenhouse gas emissions of the blast furnace is being addressed in an ongoing[when?]European Program called ULCOS (Ultra LowCO2Steelmaking).[16]Several new process routes have been proposed and investigated in depth to cut specific emissions (CO2per ton of steel) by at least 50%. Some rely on the capture and further storage (CCS) of CO2,while others choose decarbonizing iron and steel production, by turning to hydrogen, electricity and biomass.[17]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.[needs update]

History[edit]

See also:History of ferrous metallurgy
An illustration of furnace bellows operated bywaterwheelsfrom theNong Shu,byWang Zhenin 1313 during China'sYuan dynasty
A Chinese fining and blast furnace inTiangong Kaiwu,1637

Cast iron has been found inChinadating to the 5th century BC, but the earliest extant blast furnaces in China date to the 1st century AD and in the West from theHigh Middle Ages.[18]They spread from the region aroundNamurinWallonia(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 inventorAbraham Darbyin 1709. The efficiency of the process was further enhanced by the practice of preheating the combustion air (hot blast), patented by Scottish inventorJames Beaumont Neilsonin 1828.[19]

China[edit]

See also:History of metallurgy in China

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[clarification needed]by the discovery of 'more than ten' iron digging implements found in the tomb ofDuke Jing of Qin(d. 537 BC), whose tomb is located inFengxiang County,Shaanxi(a museum exists on the site today).[20]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.[21]

Althoughcast ironfarm 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 blast furnaces constructed were attributed to theHan dynastyin the 1st century AD.[22]These early furnaces had clay walls and usedphosphorus-containing minerals as aflux.[23]Chinese blast furnaces ranged from around two to ten meters in height, depending on the region. The largest ones were found in modernSichuanandGuangdong,while the 'dwarf "blast furnaces were found inDabieshan.In construction, they are both around the same level of technological sophistication.[24]

The effectiveness of the Chinese human and horse powered blast furnaces was enhanced during this period by the engineerDu Shi(c. AD 31), who applied the power ofwaterwheelstopiston-bellowsin forging cast iron.[25]Early water-driven reciprocators for operating blast furnaces were built according to 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 abelt drive,a crank-and-connecting-rod, otherconnecting rods,and various shafts, into the reciprocal motion necessary to operate a push bellow.[26][27]Donald Wagner suggests that early blast furnace and cast iron production evolved from furnaces used to meltbronze.Certainly, though, iron was essential to military success by the time theState of Qinhad unified China (221 BC). Usage of the blast and cupola furnace remained widespread during theSongandTang dynasties.[28]By the 11th century, theSong dynastyChinese iron industry made a switch of resources fromcharcoaltocokein casting iron and steel, sparing thousands of acres of woodland from felling. This may have happened as early as the 4th century AD.[29][30]

The primary advantage of the early blast furnace was in large scale production and making iron implements more readily available to peasants.[31]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.[32]

Blast furnaces were also later used to producegunpowderweapons such as cast ironbomb shellsand cast ironcannonsduring theSong dynasty.[33]

Medieval Europe[edit]

The simplestforge,known as the Corsican, was used prior to the advent ofChristianity.Examples of improved bloomeries are the Stuckofen,[34]sometimes called wolf-furnace,[35]which remained until the beginning of the 19th century. Instead of using natural draught, air was pumped in by atrompe,resulting in better quality iron and an increased capacity. This pumping of air in with bellows is known ascold blast,and it increases thefuel efficiencyof the bloomery and improves yield. They can also be built bigger than natural draught bloomeries.

Oldest European blast furnaces[edit]

The oldest known blast furnaces in the West were built inDurstelinSwitzerland,the MärkischeSauerlandinGermany,and atLapphyttaninSweden,where the complex was active between 1205 and 1300.[36]At Noraskog in the Swedish parish of Järnboås, traces of even earlier blast furnaces have been found, possibly from around 1100.[37]These early blast furnaces, like theChineseexamples, were very inefficient compared to those used today. The iron from the Lapphyttan complex was used to produce balls ofwrought ironknown asosmonds,and these were traded internationally – a possible reference occurs in a treaty withNovgorodfrom 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 inWestphalia.[38]

The technology required for blast furnaces may have either been transferred from China, or may have been an indigenous innovation.Al-Qazviniin the 13th century and other travellers subsequently noted an iron industry in theAlburzMountains to the south of theCaspian Sea.This is close to thesilk route,so that the use of technology derived from China is conceivable. Much later descriptions record blast furnaces about three metres high.[39]As theVarangianRus' peoplefromScandinaviatraded with the Caspian (using theirVolga trade route), it is possible that the technology reached Sweden by this means.[40]The Vikings are known to have used double bellows, which greatly increases the volumetric flow of the blast.[41]

The Caspian region may also have been the source for the design of the furnace atFerriere,described byFilarete,[42]involving a water-powered bellows at Semogo inValdidentroin northern Italy in 1226. In a two-stage process the molten iron was tapped twice a day into water, thereby granulating it.[43]

Cistercian contributions[edit]

The General Chapter of theCistercianmonks spread some technological advances across Europe. This may have included the blast furnace, as the Cistercians are known to have been skilledmetallurgists.[44]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 after a time surpluses were offered for sale. The Cistercians became the leading iron producers inChampagne,France, from the mid-13th century to the 17th century,[45]also using thephosphate-rich slag from their furnaces as an agriculturalfertilizer.[46]

Archaeologists are still discovering the extent of Cistercian technology.[47]AtLaskill,an outstation ofRievaulx Abbeyand the only medieval blast furnace so far identified inBritain,the slag produced was low in iron content.[48]Slag from other furnaces of the time contained a substantial concentration of iron, whereas Laskill is believed to have produced cast iron quite efficiently.[48][49][50]Its date is not yet clear, but it probably did not survive untilHenry VIII'sDissolution of the Monasteriesin the late 1530s, as an agreement (immediately after that) concerning the "smythes" with theEarl of Rutlandin 1541 refers to blooms.[51]Nevertheless, the means by which the blast furnace spread in medieval Europe has not finally been determined.

Origin and spread of early modern blast furnaces[edit]

Drawing of an 18th-century blast furnace
Early modern blast furnace pictured in the former coat of arms ofLohtaja

Due to the increased demand for iron for casting cannons, the blast furnace came into widespread use in France in the mid 15th century.[52][53]

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 thePays de Brayon the eastern boundary ofNormandyand from there to theWealdofSussex,where the first furnace (called Queenstock) inBuxtedwas built in about 1491, followed by one atNewbridgeinAshdown Forestin 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 tofinery forgesfor the production ofbar iron.[54]

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 fromSwedenand 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.[55]

The first blast furnace inRussiaopened in 1637 nearTulaand was called the Gorodishche Works. The blast furnace spread from there to central Russia and then finally to theUrals.[56]

Coke blast furnaces[edit]

The original blast furnaces atBlists HillinMadeley, England
Charging the experimental blast furnace, a photo from the Fixed Nitrogen Research Laboratory inWashington D.C.,1930
Remnants of a blast furnace inRussiafirst commissioned in 1715 by order ofPeter the Greatwith the help of Holland masters.[citation needed]

In 1709, atCoalbrookdalein Shropshire, England,Abraham Darbybegan to fuel a blast furnace withcokeinstead ofcharcoal.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.[57][58]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.)[59]: 123–125 [60][61][52]: 122–123 

Coke iron was initially only used forfoundrywork, 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 offinery forgeswith 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 BritishIndustrial Revolution.[62][63][64]Darby's original blast furnace has been archaeologically excavated and can be seen in situ at Coalbrookdale, part of theIronbridge GorgeMuseums. Cast iron from the furnace was used to makegirdersfor the world's first cast iron bridge in 1779.The Iron Bridgecrosses theRiver Severnat Coalbrookdale and remains in use for pedestrians.

The first coke blast furnace inGermany(1794-), depicted in a miniature in theDeutsches Museum

Steam-powered blast[edit]

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 asteam enginereplaced a horse-powered pump in 1742.[65]Such engines were used to pump water to a reservoir above the furnace. The first engines used to blow cylinders directly was supplied byBoulton and WatttoJohn Wilkinson'sNew WilleyFurnace.[66]This powered acast iron blowing cylinder,which had been invented by his fatherIsaac Wilkinson.He patented such cylinders in 1736,[67]to replace the leather bellows, which wore out quickly. Isaac was granted a second patent, also for blowing cylinders, in 1757.[68]The steam engine and cast iron blowing cylinder led to a large increase in British iron production in the late 18th century.[52]

Hot blast[edit]

Hot blastwas the single most important advance in fuel efficiency of the blast furnace and was one of the most important technologies developed during theIndustrial Revolution.[69][70]Hot blast was patented byJames Beaumont NeilsonatWilsontown Ironworksin 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.[71]

Hot blast enabled the use of rawanthracitecoal, which was difficult to light, in the blast furnace. Anthracite was first tried successfully by George Crane atYnyscedwyn Ironworksin south Wales in 1837.[72]It was taken up in America by theLehigh Crane Iron CompanyatCatasauqua, Pennsylvania,in 1839. Anthracite use declined when very high capacity blast furnaces requiring coke were built in the 1870s.

Modern applications of the blast furnace[edit]

Iron blast furnaces[edit]

The blast furnace remains an important part of modern iron production. Modern furnaces are highly efficient, includingCowper stovestopre-heatthe 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.[73]

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.

According toGlobal Energy Monitor,the blast furnace is likely to become obsolete to meetclimate changeobjectives of reducing carbon dioxide emission,[74]butBHPdisagrees.[75]An alternative process involvingdirect reduced ironis likely to succeed it,[citation needed]but this also needs to use a blast furnace to melt the iron and remove thegangue(impurities) unless the ore is very high quality.[75]

Oxygen blast furnace[edit]

The oxygen blast furnace (OBF) process has been extensively studied theoretically because of the potentials of promising energy conservation and CO2emission reduction.[76]This type may be the most suitable for use with CCS.[75]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 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.[77]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.[78]The base of the furnace is a hearth ofrefractory material(bricks or castable refractory).[78]Lead blast furnaces are often open-topped rather than having the charging bell used in iron blast furnaces.[79]

The blast furnace used at theNyrstarPort Pirielead smelter differs from most other lead blast furnaces in that it has a double row of tuyeres rather than the single row normally used.[77]The lower shaft of the furnace has a chair shape with the lower part of the shaft being narrower than the upper.[77]The lower row of tuyeres being located in the narrow part of the shaft.[77]This allows the upper part of the shaft to be wider than the standard.[77]

Zinc blast furnaces[edit]

The blast furnaces used in theImperial Smelting Process( "ISP" ) were developed from the standard lead blast furnace, but are fully sealed.[80]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.[80]

Blast furnaces used in the ISP have a more intense operation than standard lead blast furnaces, with higher air blast rates per m2of hearth area and a higher coke consumption.[80]

Zinc production with the ISP is more expensive than withelectrolytic zincplants, so several smelters operating this technology have closed in recent years.[81]However, ISP furnaces have the advantage of being able to treat zinc concentrates containing higher levels of lead than can electrolytic zinc plants.[80]

Manufacture of stone wool[edit]

Tuyeres of a blast furnace inGerdau,Brazil

Stone wool orrock woolis a spun mineralfibreused as aninsulationproduct and inhydroponics.It is manufactured in a blast furnace fed withdiabaserock which contains very low levels of metal oxides. The resultant slag is drawn off and spun to form the rock wool product.[82]Very small amounts of metals are also produced which are an unwantedby-product.

Modern iron process[edit]

Blast furnace placed in an installation
  1. Iron ore + limestone sinter
  2. Coke
  3. Elevator
  4. Feedstock inlet
  5. Layer of coke
  6. Layer of sinter pellets of ore and limestone
  7. Hot blast (around 1200 °C)
  8. Removal of slag
  9. Tapping of molten pig iron
  10. Slag pot
  11. Torpedo car for pig iron
  12. Dust cyclone for separation of solid particles
  13. Cowper stoves for hot blast
  14. Smoke stack
  15. Feed air for Cowper stoves (air pre-heaters)
  16. Powdered coal
  17. Coke oven
  18. Coke
  19. Blast furnace gas downcomer
Blast furnace diagram
  1. Hot blastfromCowper stoves
  2. Melting zone (bosh)
  3. Reduction zone offerrous oxide(barrel)
  4. Reduction zone offerric oxide(stack)
  5. Pre-heating zone (throat)
  6. Feed of ore, limestone, and coke
  7. Exhaust gases
  8. Column of ore, coke and limestone
  9. Removal ofslag
  10. Tapping of moltenpig iron
  11. Collection of waste gases

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, orrail hoppersandore 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 askipcar powered by winches or conveyor belts.[83]

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.[84][85]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.[84]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.[86]

The iron making blast furnace itself is built in the form of a tall structure, lined withrefractorybrick, 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,limestoneflux, 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 aventuri scrubberand/or electrostatic precipitators and a gas cooler to reduce the temperature of the cleaned gas.[83]

The "casthouse" at the bottom half of the furnace contains the bustle[clarification needed]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.[83]Once the pig iron and slag has been tapped, the taphole is again plugged with refractory clay.

Thetuyeresare used to implement ahot 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 to 1,300 °C (1,650 to 2,370 °F) depending on the stove design and condition. The temperatures they deal with may be 2,000 to 2,300 °C (3,630 to 4,170 °F).Oil,tar,natural gas,powderedcoalandoxygencan 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.[83]

The exhaust gasses of a blast furnace are generally cleaned in thedust collector– such as aninertialseparator, abaghouse,or anelectrostatic precipitator.Each type of dust collector has strengths and weaknesses – some collect fine particles, some coarse particles, some collect electrically charged particles. Effective exhaust clearing relies on multiple stages of treatment.[87]Waste heat is usually collected from the exhaust gases, for example by the use of aCowper stove,a variety ofheat exchanger.

The IEA Green House Gas R&D Programme (IEAGHG) has shown that in an integrated steel plant, 70% of the CO2is directly from the blast furnace gas (BFG). It is possible to use carbon capture technology on the BFG before the BFG goes on to be used for heat exchange processes within the plant. In 2000, the IEAGHG estimated using that chemical absorption to capture BFG would cost $35/t of CO2(an additional $8–20/t of CO2would be required for CO2transportation and storage). This would make the entire steel production process in a plant 15–20% more expensive.[88]

Environmental impact[edit]

A drawing of a blast furnace dust catcher

The results showed thatglobal warmingpotential andacidificationpotential were the most significant environmental impacts. On average producing a tonne of steel emits 1.8 tonnes of CO2.[6][89]However, a steel mill using a top gas recycling blast furnace (TGRBF) producing a tonne of steel will emit 0.8 to 1.3 tonnes of CO2depending upon the recycle rate of the TGRBF.[90]

Decommissioned blast furnaces as museum sites[edit]

Main article:List of preserved historic blast furnaces

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, theCzech Republic,Great Britain.Japan,Luxembourg,Poland,Romania,Mexico,Russiaand theUnited States.

Gallery[edit]

  • Abandoned blast furnace in Sestao, Spain. The furnace itself is inside the central girderwork.
    Abandoned blast furnace inSestao,Spain. The furnace itself is inside the central girderwork.
  • Part of the gas cleaning system of a blast furnace in Monclova, Mexico. This one is about to be de-commissioned and replaced.
    Part of the gas cleaning system of a blast furnace inMonclova,Mexico. This one is about to be de-commissioned and replaced.

See also[edit]

References[edit]

  1. ^See:Draft (boiler)
  2. ^Schmult, Brian (2016). "Evolution of the Hopewell Furnace Blast Machinery".IA. The Journal of the Society for Industrial Archeology.42(2): 5–22.
  3. ^Development of heat transfer circuits in the blast furnace, IOP Conference Series: Materials Science and Engineering
  4. ^P J Wand, "Copper smelting at Electrolytic Refining and Smelting Company of Australia Ltd., Port Kembla, N.S.W.", in:Mining and Metallurgical Practices in Australasia: The Sir Maurice Mawby Memorial Volume,Ed J T Woodcock (The Australasian Institute of Mining and Metallurgy: Melbourne, 1980) 335–340.
  5. ^R J Sinclair,The Extractive Metallurgy of Lead(The Australasian Institute of Mining and Metallurgy: Melbourne, 2009), 9–12.
  6. ^abPooler, Michael (January 2019)."Cleaning up steel is key to tackling climate change".Financial Times.Archivedfrom the original on 10 December 2022.Retrieved7 July2021.
  7. ^Oeters, Franz; Ottow, Manfred; Meiler, Heinrich; Lüngen, Hans Bodo; Koltermann, Manfred; Buhr, Andreas; Yagi, Jun-Ichiro; Formanek, Lothar; Rose, Fritz; Flickenschild, Jürgen; Hauk, Rolf; Steffen, Rolf; Skroch, Reiner; Mayer-Schwinning, Gernot; Bünnagel, Heinz-Lothar; Hoff, Hans-Georg (2006). "Iron".Ullmann's Encyclopedia of Industrial Chemistry.Weinheim: Wiley-VCH.doi:10.1002/14356007.a14_461.pub2.ISBN978-3527306732.
  8. ^ab"Blast Furnace".Science Aid. Archived fromthe originalon 17 December 2007.Retrieved30 December2007.
  9. ^abcdefRayner-Canham & Overton (2006),Descriptive Inorganic Chemistry, Fourth Edition,New York: W. H. Freeman and Company, pp. 534–535,ISBN978-0-7167-7695-6
  10. ^Dr. K. E. Lee, Form Two Science (Biology Chemistry Physics)
  11. ^Flowers, Paul; Robinson, William R.; Langley, Richard; Theopold, Klaus (2015)."Occurrence, Preparation, and Properties of Transition Metals and Their Compounds".Chemistry.OpenStax.ISBN978-1938168390.
  12. ^tec-science (21 June 2018)."From pig iron to crude steel".tec-science.Retrieved2 November2019.
  13. ^Wang, Peng; Ryberg, Morten; Yang, Yi; Feng, Kuishuang; Kara, Sami; Hauschild, Michael; Chen, Wei-Qiang (6 April 2021)."Efficiency stagnation in global steel production urges joint supply- and demand-side mitigation efforts".Nature Communications.12(1): 2066.Bibcode:2021NatCo..12.2066W.doi:10.1038/s41467-021-22245-6.ISSN2041-1723.PMC8024266.PMID33824307.
  14. ^De Ras, Kevin; Van De Vijver, Ruben; Galvita, Vladimir V.; Marin, Guy B.; Van Geem, Kevin M. (1 December 2019)."Carbon capture and utilization in the steel industry: challenges and opportunities for chemical engineering".Current Opinion in Chemical Engineering.26:81–87.Bibcode:2019COCE...26...81D.doi:10.1016/j.coche.2019.09.001.hdl:1854/LU-8635595.ISSN2211-3398.S2CID210619173.
  15. ^Hoffmann, Christian; Van Hoey, Michel; Zeumer, Benedikt (April 2020)."Decarbonization challenge for steel: Hydrogen as a solution in Europe"(PDF).McKinsey & Company. p. 6.
  16. ^http:// ulcos.orgArchived21 November 2008 at theWayback Machine
  17. ^ICIT-Revue de Métallurgie, September and October issues, 2009
  18. ^Peter J. Golas (1999).Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 13, Mining.Cambridge University Press. p. 152.ISBN978-0-521-58000-7....earliest blast furnace discovered in China from about the first century AD
  19. ^Simcoe, Charles R. "The Age of Steel: Part II." Advanced Materials & Processes 172.4 (2014): 32–33. Academic Search Premier.
  20. ^"The Earliest Use of Iron in China" by Donald B. Wagner inMetals in Antiquity,by Suzanne M. M. Young, A. Mark Pollard, Paul Budd and Robert A. Ixer (BAR International Series, 792), Oxford:Archaeopress,1999, pp. 1–9.
  21. ^Wagner 2008,p. 230.
  22. ^Ebrey, p. 30.
  23. ^Early iron in China, Korea, and JapanArchived5 February 2007 at theWayback Machine,Donald B. Wagner, March 1993
  24. ^Wagner 2008,p. 6.
  25. ^Needham, Joseph (1986),Science and Civilisation in China, Volume 4: Physics and Physical Technology, Part 2, Mechanical Engineering,Taipei: Cambridge University Press, p. 370,ISBN0-521-05803-1
  26. ^Hong-Sen Yan, Marco Ceccarelli (2009).International Symposium on History of Machines and Mechanisms.Springer Science and Business Media. pp. 235–249.ISBN978-1-4020-9484-2.
  27. ^Needham 1986,pp. 118–119.
  28. ^The Coming of the Ages of Steel.Brill Archive. 1961. p. 54. GGKEY:DN6SZTCNQ3G.
  29. ^Donald B. Wagner, 'Chinese blast furnaces from the 10th to the 14th century'Historical Metallurgy37(1) (2003), 25–37; originally published inWest Asian Science, Technology, and Medicine18 (2001), 41–74.
  30. ^Ebrey, p. 158.
  31. ^Wagner 2008,p. 169.
  32. ^Wagner 2008,p. 1.
  33. ^Liang 2006.
  34. ^Julius H. Strassburger (1969).Blast Furnace-theory and Practice.Gordon and Breach Science Publishers. p. 4.ISBN978-0-677-10420-1.Retrieved12 July2012.
  35. ^Douglas Alan Fisher,Excerpt from The Epic of SteelArchived25 February 2007 at theWayback Machine,Davis Town Museum & Harper & Row, NY 1963.
  36. ^Jockenhövel, Albrechtet al.(1997)"Archaeological Investigations on the Beginning of Blast Furnace-Technology in Central Europe"Archived24 February 2013 at theWayback MachineAbteilung für Ur- und Frühgeschichtliche Archäologie, Westfälische Wilhelms-Universität Münster; abstract published as: Jockenhövel, A. (1997) "Archaeological Investigations on the Beginning of Blast Furnace-Technology in Central Europe" pp. 56–58InCrew, Peter and Crew, Susan (editors) (1997)Early Ironworking in Europe: Archaeology and Experiment: Abstracts of the International Conference at Plas Tan y Bwlch 19–25 September 1997(Plas Tan y Bwlch Occasional Papers No 3) Snowdonia National Park Study Centre, Gwynedd, Wales,OCLC470699473;archived here[1]byWebCiteon 11 March 2012
  37. ^A. Wetterholm, 'Blast furnace studies in Nora bergslag' (Örebro universitet 1999, Järn och Samhälle)ISBN91-7668-204-8
  38. ^N. Bjökenstam, 'The Blast Furnace in Europe during the Middle Ages: part of a new system for producing wrought iron' in G. Magnusson,The Importance of Ironmaking: Technological Innovation and Social ChangeI (Jernkontoret, Stockholm 1995), 143–153 and other papers in the same volume.
  39. ^Wagner 2008, 349–351.
  40. ^Wagner 2008, 354.
  41. ^Markewitz, Darrell (25 March 2006)."Adventures in Early Iron Production – An overview of experimental iron smelts, 2001–2005".warehamforge.ca.Archivedfrom the original on 22 September 2015.
  42. ^Wagner 2008, 355.
  43. ^Awty, B. G. (January 1989). "The Blast Furnace in the Renaissance Period:Haut FourneauorFonderie?".Transactions of the Newcomen Society.61(1): 65–78.doi:10.1179/tns.1989.005.
  44. ^Woods, p. 34.
  45. ^Gimpel, p. 67.
  46. ^Woods, p. 35.
  47. ^Woods, p. 36.
  48. ^abWoods, p. 37.
  49. ^R. W. Vernon, G. McDonnell and A. Schmidt (1998). "An integrated geophysical and analytical appraisal of early iron-working: three case studies".Historical Metallurgy.32(2): 72–75, 79.
  50. ^David Derbyshire,'Henry "Stamped Out Industrial Revolution" 'Archived13 June 2014 at theWayback Machine,The Daily Telegraph(21 June 2002); cited by Woods.
  51. ^Schubert, H. R. (1957),History of the British iron and steel industry from c. 450 BC to AD 1775,Routledge & Kegan Paul, pp. 395–397
  52. ^abcTylecote, R. F. (1992).A History of Metallurgy, Second Edition.London: Maney Publishing, for the Institute of Materials.ISBN978-0901462886.
  53. ^Merson, John (1990).The Genius That Was China: East and West in the Making of the Modern World.Woodstock, New York: The Overlook Press. p.69.ISBN0-87951-397-7A companion to the PBS Series "The Genius That Was China"{{cite book}}:CS1 maint: postscript (link)
  54. ^Awty, Brian; Whittick, Christopher (2002)."The Lordship of Canterbury, iron-founding at Buxted, and the continental antecedents of cannon-founding in the Weald".Sussex Archaeological Collections.140:71–81.doi:10.5284/1085896.
  55. ^P. W. King, 'The production and consumption of iron in early modern England and Wales'Economic History ReviewLVIII(1), 1–33; G. Hammersley, 'The charcoal iron industry and its fuel 1540–1750'Economic History ReviewSer. II, XXVI (1973), pp. 593–613.
  56. ^Yakovlev, V. B. (1957), "Development of Wrought Iron Production",Metallurgist,1(8), New York: Springer: 545,doi:10.1007/BF00732452,S2CID137551466
  57. ^ Landes, David. S.(1969).The Unbound Prometheus: Technological Change and Industrial Development in Western Europe from 1750 to the Present.Cambridge; New York: Press Syndicate of the University of Cambridge. pp. 90–93.ISBN0-521-09418-6.
  58. ^ Rosen, William (2012).The Most Powerful Idea in the World: A Story of Steam, Industry and Invention.University of Chicago Press. p. 149.ISBN978-0226726342.
  59. ^Tylecote, R. F. (1992).A History of Metallurgy, Second Edition.London: Maney Publishing, for the Institute of Materials.ISBN978-0901462886.
  60. ^McNeil, Ian (1990).An Encyclopedia of the History of Technology.London: Routledge.ISBN0415147921.
  61. ^"Coke for Blast Furnace Ironmaking".steel.org.Archived fromthe originalon 8 February 2017.
  62. ^Raistrick, Arthur (1953),Dynasty of Iron Founders: The Darbys and Coalbrookedale,York: Longmans, Green
  63. ^Hyde
  64. ^Trinder, Barrie Stuart; Trinder, Barrie (2000),The Industrial Revolution in Shropshire,Chichester: Phillimore,ISBN1-86077-133-5
  65. ^A. Raistrick,Dynasty of ironmasters(Sessions, York, 1989), 138–139.
  66. ^H.W. Dickinson and Rhys Jenkins,James Watt and the steam engine(Moorland, Ashbourne 1981 edn), 111–112.
  67. ^English patent, no.553.
  68. ^English patent, no.713.
  69. ^ Landes, David. S.(1969).The Unbound Prometheus: Technological Change and Industrial Development in Western Europe from 1750 to the Present.Cambridge; New York: Press Syndicate of the University of Cambridge. p. 92.ISBN0-521-09418-6.
  70. ^Ayres, Robert(1989)."Technological Transformations and Long Waves"(PDF).p. 21. Archived fromthe original(PDF)on 1 March 2012.Retrieved17 October2013.Fig. 7 shows C/Fe ratio time series.
  71. ^Birch, pp. 181–189.
  72. ^Hyde, p. 159.
  73. ^"POSCO Gwangyang blast furnace emerges as world largest",The Dong-a Ilbo,10 June 2013
  74. ^"Steel sector may be saddled with up to $70 bln stranded assets -report".Reuters.29 June 2021.Retrieved10 July2021.
  75. ^abc"Pathways to decarbonisation episode two: steelmaking technology".Archivedfrom the original on 5 November 2020.
  76. ^Zhang, Wei; Dai, Jing; Li, Chengzhi; Yu, Xiaobing; Xue, Zhengliang; Saxén, Henrik (January 2021)."A Review on Explorations of the Oxygen Blast Furnace Process".Steel Research International.92(1): 2000326.doi:10.1002/srin.202000326.ISSN1611-3683.S2CID224952826.
  77. ^abcdeR J Sinclair,The Extractive Metallurgy of Lead(The Australasian Institute of Mining and Metallurgy: Melbourne, 2009), 77.
  78. ^abR J Sinclair,The Extractive Metallurgy of Lead(The Australasian Institute of Mining and Metallurgy: Melbourne, 2009), 75.
  79. ^R J Sinclair,The Extractive Metallurgy of Lead(The Australasian Institute of Mining and Metallurgy: Melbourne, 2009), 76.
  80. ^abcdR J Sinclair,The Extractive Metallurgy of Lead(The Australasian Institute of Mining and Metallurgy: Melbourne, 2009), 89.
  81. ^R J Sinclair,The Extractive Metallurgy of Lead(The Australasian Institute of Mining and Metallurgy: Melbourne, 2009), 90.
  82. ^"What is stone wool?".rockwool.co.uk.Archived fromthe originalon 10 February 2010.
  83. ^abcdAmerican Iron and Steel Institute (2005).How a Blast Furnace Works.steel.org.
  84. ^abMcNeil, Ian (1990),An encyclopaedia of the history of technology,Taylor & Francis, p. 163,ISBN0-415-01306-2
  85. ^Strassburger, Julius H. (1969),Blast furnace: Theory and Practice,Taylor & Francis, p. 564,ISBN0-677-10420-0
  86. ^Whitfield, Peter,Design and Operation of a Gimbal Top Charging System(PDF),archived fromthe original(PDF)on 5 March 2009,retrieved22 June2008
  87. ^"Comparison of techniques employed at Scunthorpe Integrated Steelworks with those in the BAT Conclusions for Iron and Steel Production published in the Official Journal of the European Union"(PDF).HM Government UK. 8 March 2012.Retrieved19 January2021.
  88. ^IEA-GHG, 2000. Greenhouse Gas Emissions from Major Industrial Sources – Iron and Steel Production. Report no. PH3/30. Cheltenham, UK, IEA Greenhouse Gas R&D Programme.https://ieaghg.org/docs/General_Docs/Reports/PH3-30%20iron-steel.pdfAccessed July 30, 2021.
  89. ^"Direct CO2 intensity of the iron and steel sector in the Net Zero Scenario, 2010-2030 – Charts – Data & Statistics".IEA.
  90. ^Ho, Minh T.; Bustamante, Andrea; Wiley, Dianne E. (November 2013)."Comparison of CO2capture economics for iron and steel mills ".International Journal of Greenhouse Gas Control.19:145–159.Bibcode:2013IJGGC..19..145H.doi:10.1016/j.ijggc.2013.08.003.

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