steel making handout

7/21/2019 Steel Making Handout

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IRON AND STEEL MAKING

HANDOUT -2 : STEEL MAKING

STEEL MAKING

Steelmakingis the second step in producing steelfrom iron ore. In this stage,impurities such as sulfur, phosphorus, and excess caronare remo!ed from the ra"iron, and allo#ing elements such as manganese, nic$el, chromiumand !anadiumare added to produce the exact steel re%uired.

Older pr!e""e"

&ethlehem Steelin &ethlehem, 'enns#l!ania"as one of the "orld(s largestmanufacturers of steel efore its )**+ closure.

The earliest means of producing steel "as in a loomer#.

Earl# modern methods of producing steel "ere often laourintensi!e and highl#s$illed arts.

German -ner# processcould e managed to produce steel. lister steeland crucilesteel.

Older pr!e""e"

An important aspect of the industrial re!olution"as the de!elopment of largescale

methods of producing forgeale metal ar ironor steel/. The puddling furnace"asinitiall# a means of producing "rought iron, ut "as later applied to steelproduction.

The real re!olution in steelma$ing onl# egan at the end of the 012*s. The&essemer process"as the -rst successful method of steelma$ing in %uantit#,follo"ed # the open hearth furnace.

Mdern pr!e""e"

Modern steelma$ing processes are ro$en into t"o categories3

'rimar# steelma$ing uses mostl# ne" iron as the feedstoc$, usuall# from a lastfurnace.

Secondar# steelma$ing uses scrap steel as the primar# ra" material.

#e""emer pr!e""
http://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Iron_orehttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Pig_ironhttp://en.wikipedia.org/wiki/Pig_ironhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Chromiumhttp://en.wikipedia.org/wiki/Vanadiumhttp://en.wikipedia.org/wiki/Bethlehem_Steelhttp://en.wikipedia.org/wiki/Bethlehem,_Pennsylvaniahttp://en.wikipedia.org/wiki/Bloomeryhttp://en.wikipedia.org/wiki/German_inventions_and_discoverieshttp://en.wikipedia.org/wiki/Blister_steelhttp://en.wikipedia.org/wiki/Crucible_steelhttp://en.wikipedia.org/wiki/Crucible_steelhttp://en.wikipedia.org/wiki/Industrial_revolutionhttp://en.wikipedia.org/wiki/Bar_ironhttp://en.wikipedia.org/wiki/Puddling_furnacehttp://en.wikipedia.org/wiki/Wrought_ironhttp://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Open_hearth_furnacehttp://en.wikipedia.org/wiki/Blast_furnacehttp://en.wikipedia.org/wiki/Blast_furnacehttp://en.wikipedia.org/wiki/Iron_orehttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Pig_ironhttp://en.wikipedia.org/wiki/Pig_ironhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Chromiumhttp://en.wikipedia.org/wiki/Vanadiumhttp://en.wikipedia.org/wiki/Bethlehem_Steelhttp://en.wikipedia.org/wiki/Bethlehem,_Pennsylvaniahttp://en.wikipedia.org/wiki/Bloomeryhttp://en.wikipedia.org/wiki/German_inventions_and_discoverieshttp://en.wikipedia.org/wiki/Blister_steelhttp://en.wikipedia.org/wiki/Crucible_steelhttp://en.wikipedia.org/wiki/Crucible_steelhttp://en.wikipedia.org/wiki/Industrial_revolutionhttp://en.wikipedia.org/wiki/Bar_ironhttp://en.wikipedia.org/wiki/Puddling_furnacehttp://en.wikipedia.org/wiki/Puddling_furnacehttp://en.wikipedia.org/wiki/Wrought_ironhttp://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Open_hearth_furnacehttp://en.wikipedia.org/wiki/Blast_furnacehttp://en.wikipedia.org/wiki/Blast_furnacehttp://en.wikipedia.org/wiki/Steel


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The #e""emer pr!e"""as the -rst inexpensi!e industrial processfor the massproduction of steelfrom molten pig iron.

4enr# &essemer, "ho too$ out a patenton the process in 0122.

The process "as independentl# disco!ered in 0120 # 5illiam Kell#.

#e""emer pr!e""

The process had also een used outside of Europe for hundreds of #ears, ut not onan industrial scale.

T$e ke% prin!iple i"

rem&al ' imp(ritie"'rm t$e irn)% *idatin

+it$ air )eing )l+n t$r(g$ t$e mlten irn,

T$e *idatin al" rai"e" t$e temperat(re ' t$e irn ma"" and keep" it

mlten,

basic Bessemer process

The process using a asic refractor# lining is $no"n as the basic Bessemer processor Gilchrist-Thomas processafter the disco!erer Sidne# Gilchrist Thomas

O*idatin

The oxidation process remo!es impurities such as silicon, manganese, and caronas oxides.

These oxides either escape as gas or form a solid slag.

The re'ra!tr% lining ' t$e !n&erter also pla#s a role in the con!ersion6thecla# lining is used in the acidBessemer, in "hich there is lo" phosphorusin the ra"material.

O*idatin

7olomiteis used "hen the phosphorus content is high in the basicBessemer

limestoneor magnesitelinings are also sometimes used instead of dolomite/6thisis also $no"n as a Gilchrist-Thomas converter, named after its in!entor, Sidne#Gilchrist Thomas.

In order to gi!e the steel the desired properties, other sustances could e added tothe molten steel "hen con!ersion "as complete, such as spiegeleisenan ironcaronmanganese allo#/.
http://en.wikipedia.org/wiki/Industrial_processhttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Pig_ironhttp://en.wikipedia.org/wiki/Henry_Bessemerhttp://en.wikipedia.org/wiki/Patenthttp://en.wikipedia.org/wiki/William_Kelly_(inventor)http://en.wikipedia.org/wiki/Steelmakinghttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Sidney_Gilchrist_Thomashttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Dolomitehttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Magnesitehttp://en.wikipedia.org/wiki/Sidney_Gilchrist_Thomashttp://en.wikipedia.org/wiki/Sidney_Gilchrist_Thomashttp://en.wikipedia.org/wiki/Spiegeleisenhttp://en.wikipedia.org/wiki/Industrial_processhttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Pig_ironhttp://en.wikipedia.org/wiki/Henry_Bessemerhttp://en.wikipedia.org/wiki/Patenthttp://en.wikipedia.org/wiki/William_Kelly_(inventor)http://en.wikipedia.org/wiki/Steelmakinghttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Sidney_Gilchrist_Thomashttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Dolomitehttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Magnesitehttp://en.wikipedia.org/wiki/Sidney_Gilchrist_Thomashttp://en.wikipedia.org/wiki/Sidney_Gilchrist_Thomashttp://en.wikipedia.org/wiki/Spiegeleisen


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Managing t$e pr!e""

5hen the re%uired steel had een formed, it "as poured out into ladles and thentransferred into moulds and the lighter slag is left ehind.

The con!ersion process called the 8lo"8 "as completed in around t"ent# minutes.

7uring this period the progress of the oxidation of the impurities "as 9udged # theappearance of the :ame issuing from the mouth of the con!erter3 the modern use ofphotoelectric methods of recording the characteristics of the :ame has greatl#aided the lo"er in controlling the -nal %ualit# of the product.

After the lo", the li%uid metal "as recaruri;ed to the desired point and otherallo#ing materials are added, depending on the desired produc

O)"le"!en!e

In the 1.It "as replaced # processes such as the asic ox#gen Lin; 7ona"it; / process,"hich o?ered etter control of -nal chemistr#.

The &essemer process "as so fast 0*@)* minutes for a heat/ that it allo"ed littletime for chemical anal#sis or ad9ustment of the allo#ing elements in the steel.

&essemer con!erters did not remo!e phosphorus ecientl# from the molten steelBas lo"phosphorus ores ecame more expensi!e, con!ersion costs increased.

The process permitted onl# limited amount of scrapsteel to e charged, further

increasing costs, especiall# "hen scrap "as inexpensi!e.


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Since steelis dicult to manufacture due to its high melting point, normal fuels andfurnaces "ere insucient and the open hearth furnace "as de!eloped to o!ercomethis dicult#.

Most open hearth furnaces "ere closed # the earl# 0==*s, not least ecause of

their fuel inecienc#, eing replaced # the asic ox#gen furnaceor electric arcfurnace.

CATALAN DFGE

Technicall# perhaps, the -rst primiti!e open hearth furnace "as the Catalan forge,in!ented in Spain in the eighth centur#, ut it is usual to con-ne the term to certainnineteenth centur# and later steelma$ing processes, thus excluding loomeriesincluding the Catalan forge/, -ner# forges, and puddling furnacesfrom itsapplication

T$e Siemen" regenerati&e '(rna!e

Sir Carl 5ilhelm Siemensde!eloped the Siemen" regenerati&e '(rna!ein the012*s, and claimed in 012 to e reco!ering enough heat to sa!e *@1*H of thefuel.

This furnace operates at a high temperature # using regenerati!e preheatingoffuel and air for comustion.

In regenerati!e preheating, the exhaust gases from the furnace are pumped into achamer containing ric$s, "here heat is transferred from the gases to the ric$s.

The :o" of the furnace is then re!ersed so that fuel and air pass through thechamer and are heated # the ric$s.

Through this method, an openhearth furnace can reach temperatures high enoughto melt steel, ut Siemens did not initiall# use it for that.

The regenerators are the distincti!e feature of the furnace and consist of -reric$:ues -lled "ith ric$s set on edge and arranged in such a "a# as to ha!e a greatnumer of small passages et"een them.

The ric$s asor most of the heat from the outgoing "aste gases and return itlater to the incoming cold gases for comustion.

Open $eart$ "teelmaking

In 01>2, the Drench engineer 'ierre mile Martintoo$ out a license from Siemensand -rst applied his furnace for ma$ing steel. Their process "as $no"n as theSiemen"-Martin pr!e"", and the furnace as an 8openhearth8 furnace.
http://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Basic_oxygen_furnacehttp://en.wikipedia.org/wiki/Electric_arc_furnacehttp://en.wikipedia.org/wiki/Electric_arc_furnacehttp://en.wikipedia.org/wiki/Catalan_forgehttp://en.wikipedia.org/wiki/Bloomeryhttp://en.wikipedia.org/wiki/Finery_forgehttp://en.wikipedia.org/wiki/Puddling_furnacehttp://en.wikipedia.org/wiki/Carl_Wilhelm_Siemenshttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Pierre-%C3%89mile_Martinhttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Basic_oxygen_furnacehttp://en.wikipedia.org/wiki/Electric_arc_furnacehttp://en.wikipedia.org/wiki/Electric_arc_furnacehttp://en.wikipedia.org/wiki/Catalan_forgehttp://en.wikipedia.org/wiki/Bloomeryhttp://en.wikipedia.org/wiki/Finery_forgehttp://en.wikipedia.org/wiki/Puddling_furnacehttp://en.wikipedia.org/wiki/Puddling_furnacehttp://en.wikipedia.org/wiki/Carl_Wilhelm_Siemenshttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Pierre-%C3%89mile_Martinhttp://en.wikipedia.org/wiki/Pierre-%C3%89mile_Martinhttp://en.wikipedia.org/wiki/Pierre-%C3%89mile_Martinhttp://en.wikipedia.org/wiki/Steel


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The most appealing characteristic of the Siemens regenerati!e furnace is the rapidproduction of large %uantities of asic steel, used for example to construct highriseuildings.

The usual si;e of furnaces is 2* to 0** tons, ut for some special processes the#

ma# ha!e a capacit# of )2* or e!en 2** tons.The SiemensMartin process complemented rather than replaced the &essemerprocess.

It is slo"er and thus easier to control.

It also permits the melting and re-ning of large amounts of scrap steel, furtherlo"ering steel production costs and rec#cling an other"ise troulesome "astematerial.

Its "orst dra"ac$s are the energ# inecienc# and the extremel# dangerous

"or$ing en!ironment.

ne dicult# in the manufacture of steel is its high melting point, aout 0+*J Caout )2**J D/, "hich pre!ents the use of ordinar# fuels and furnaces.

To o!ercome this dicult# the openhearth furnace "as de!elopedB this furnace cane operated at a high temperature # regenerati!e preheating of the fuel gas andair used for comustion in the furnace.

In regenerati!e preheating, the exhaust gases from the furnace are dra"n throughone of a series of chamers containing a mass of ric$"or$ and gi!e up most of

their heat to the ric$s.Then the :o" through the furnace is re!ersed and the fuel and air pass through theheated chamers and are "armed # the ric$s.

Through this method openhearth furnaces can reach temperatures as high as0>2*J C

'EN 4EAFT4

T4E 'FCESS

The furnace is charged "ith a mixture of pig iron either molten or cold/, scrap steel,and iron ore that pro!ides additional ox#gen.

Limestone is added for :ux and :uorspar to ma$e the slag more :uid.

The proportions of the charge !ar# "ithin "ide limits, ut a t#pical charge mightconsist of

2>,2* $g 0)2,*** l/ of scrap steel,
http://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Bessemer_process


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00,+2* $g )2,*** l/ of cold pig iron,

2,** $g 0**,*** l/ of molten pig iron,

00,1** $g )>,*** l/ of limestone,

=** $g )*** l/ of iron ore, and

)+* $g 2** l/ of :uorspar.

After the furnace has een charged, the furnace is lighted and he

:ames pla# ac$ and forth o!er the hearth as their direction is

re!ersed # the operator to pro!ide heat regeneration.

T4E 'FCESS

Chemicall# the action of the openhearth furnace consists oflo"ering the caron content of the charge # oxidi;ation and of remo!ing suchimpurities as silicon, phosphorus, manganese, and sulphur, "hich comine "ith thelimestone to form slag.

These reactions ta$e place "hile the metal in the furnace is at melting heat, and the'(rna!e i" $eld )et+een ./01 and .01 3 425001 and 60001 78 for man#hours until the molten metal has the desired caron content.

T4E 'FCESS

Experienced openhearth operators can often 9udge the caron content of the metal# its appearance, ut the melt is usuall# tested # "ithdra"ing a small amount ofmetal from the furnace, cooling it, and su9ecting it to ph#sical examination orchemical anal#sis.

5hen the caron content of the melt reaches the desired le!el, the furnace istapped through a hole at the rear.

The molten steel then :o"s through a short trough to a large ladle set elo" thefurnace at ground le!el.

T4E 'FCESSDrom the ladle the steel is poured into castiron molds that form ingots usuall# aout0.2 m aout 2 ft/ long and 1 cm 0= in/ s%uare.

These ingots, the ra" material for all forms of faricated steel, "eigh approximatel#).)2 metric tons in this si;e.


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Methods ha!e een put into practice for the continuous processing of steel "ithout-rst ha!ing to go through the process of casting ingots

&SLENCE

The asic ox#gen steelma$inge!entuall# replaced the open hearth furnace.

It rapidl# superseded oth the &essemer process and SiemensMartin process in the5estern Europe # the 0=2*sclarifcation neededand in the Eastern Europe # the 0=1*s,the last European open hearth furnace eing stopped in 0==+.

In the


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The !ast ma9orit# of steel manufactured in the "orld is produced using the asicox#gen furnaceB in )***, it accounted for >*H of gloal steel output.

Modern furnaces "ill ta$e a charge of iron of up to +2* tons and con!ert it into steelin less than * minutes, compared to 0*@0) hours in an open hearth furnace.

The 'rocess

0. Molten pig iron sometimes referred to as 8hot metal8/ from a last furnaceispoured into a large refractor#lined container called a ladleB

). The metal in the ladle is sent directl# for asic ox#gen steelma$ing or to apretreatment stage.

'retreatment of the last furnace metal is used to reduce the re-ning load of sulfur,silicon, and phosphorus.

In desulfurising pretreatment, a lanceis lo"ered into the molten ironin the ladleand se!eral hundred $ilograms of po"dered magnesiumare added.

Sulfur impurities are reduced to magnesium sul-dein a !iolent exothermicreaction.The sul-de is then ra$ed o?.

Similar pretreatment is possile for desiliconisation and dephosphorisation usingmill scaleiron oxide/ and lime as reagents. The decision to pretreat depends on the%ualit# of the last furnace metal and the re%uired -nal %ualit# of the &S steel.

&D

+. Dilling the furnace"ith the ingredients is called charging.

The &S process is autogenous3 the re%uired thermal energ# is producedduring the process.Maintaining the proper charge balance, the ratio of hotmetal toscrap, is therefore !er# important. The &S !essel is one-fth -lled "ith steel scrap.Molten iron from the ladle is added as re%uired # the charge alance.

A t%pi!al !$emi"tr% ' $tmetal !$arged int t$e #OS &e""el i": /< 3= 0,2>

0,5< Si= 0,050,5< 9= and 0,0>0,0/< S,

. The !essel is then set upright and a "atercooled lance is lo"ered do"n into it.

The lance )l+" ??< p(re *%gen onto the steel and iron, igniting the carondissol!ed in the steel and urning it to form caron monoxideand caron dioxide,causing the temperature to rise to aout 0**JC.

This melts the scrap, lo"ers the caroncontent of the molten iron and helps remo!eun"anted chemical elements.
http://en.wikipedia.org/wiki/Open_hearth_furnacehttp://en.wikipedia.org/wiki/Blast_furnacehttp://en.wikipedia.org/wiki/Ladle_(metallurgy)http://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/w/index.php?title=Lance_(metallurgy)&action=edit&redlink=1http://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Magnesium_sulfidehttp://en.wikipedia.org/wiki/Exothermichttp://en.wikipedia.org/wiki/Mill_scalehttp://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Open_hearth_furnacehttp://en.wikipedia.org/wiki/Blast_furnacehttp://en.wikipedia.org/wiki/Ladle_(metallurgy)http://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/w/index.php?title=Lance_(metallurgy)&action=edit&redlink=1http://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Magnesium_sulfidehttp://en.wikipedia.org/wiki/Exothermichttp://en.wikipedia.org/wiki/Mill_scalehttp://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Chemical_element


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It is this use of ox#gen instead of air that impro!es upon the &essemer process, forthe nitrogen and other gases/ in air do not react "ith the charge as ox#gen does.

4igh purit# ox#gen is lo"n into the furnace or &S !essel through a !erticall#oriented "atercooled lance "ith !elocities faster than Mach 0.

2.Dluxesurnt limeor dolomite/ are fed into the !essel to form slag, "hich asorsimpurities of the steelma$ing process.

7uring lo"ing the metal in the !essel forms an emulsion "ith the slag, facilitatingthe re-ning process.

Near the end of the lo"ing c#cle, "hich ta$es aout )* minutes, the temperatureis measured and samples are ta$en.

The samples are tested and a computer anal#sis of the steel gi!en "ithin sixminutes.

T%pi!al !$emi"tr% ' t$e )l+n metal i"

0,6>0,< 3= 0,0.>0,< Mn= 0,0>0,06< Si= 0,0>0,06< S and 9,

>. The &S !essel is tilted again and the steel is poured into a giant ladle. Thisprocess is called tappingt$e "teel.

The steel is further re-ned in the ladle furnace, # adding allo#ing materials to gi!ethe steel special properties re%uired # the customer.

Sometimes argonor nitrogengas is uled into the ladle to ma$e sure the allo#s

mix correctl#.

The steel no" contains 0,>< !ar)n,

The more caron in the steel, the harder it is, ut it is also more rittle and less:exile.

. After the steel is remo!ed from the &S !essel, the slag, -lled "ith impurities,is poured o? and cooled.

E!olution of asic ox#gen 'rocess

The asic ox#gen process de!eloped outside of traditional 8ig steel8 en!ironment.

7e!eloped and re-ned # Swiss engineer Robert Durrer.

Commerciali;ed # t"o small steel companies in alliedoccupied Austria, "hich hadnot #et reco!ered from the destruction of 5orld 5ar II.
http://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Lime_(mineral)http://en.wikipedia.org/wiki/Dolomitehttp://en.wikipedia.org/wiki/Slaghttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Allied-occupied_Austriahttp://en.wikipedia.org/wiki/World_War_IIhttp://en.wikipedia.org/wiki/Bessemer_processhttp://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Lime_(mineral)http://en.wikipedia.org/wiki/Dolomitehttp://en.wikipedia.org/wiki/Slaghttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Allied-occupied_Austriahttp://en.wikipedia.org/wiki/World_War_II


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In 0121, 4enr# &essemerpatented a steelma$ing process in!ol!ing ox#gen lo"ingfor decaruri;ing molten iron


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Papan the share of L7 process decreased from 1*H in 0=* to *H in )***B"orld"ide share of the asic ox#gen process staili;ed at >*H.)

Ele!tri!-7(rna!e Steel

Electricit# instead of -re supplies the heat for the melting and re-ning of steel.

&ecause re-ning conditions in such a furnace can e regulated more strictl# than inopenhearth or asic ox#gen furnaces, ele!tri! '(rna!e" are parti!(larl%&al(a)le 'r prd(!ing "tainle"" "teel" and t$er $ig$l% all%ed "teel" thatmust e made to exacting speci-cations.

Fe-ning ta$es place in a tightl# closed chamer, "here temperatures and otherconditions are $ept under rigid control # automatic de!ices. 7uring the earl#stages of this re-ning process, highpurit# ox#gen is in9ected through a lance,raising the temperature of the furnace and decreasing the time needed to producethe -nished steel. The %uantit# of ox#gen entering the furnace can al"a#s e

closel# controlled, thus $eeping do"n undesirale oxidi;ing reactions.

T4E 'FCESS

Most often the charge consists almost entirely of scrap. &efore it is read# to eused, the scrap must -rst e anal#;ed and sorted, ecause its allo# content "illa?ect the composition of the re-ned metal.

ther materials, such as small %uantities of iron ore and dry lime, are added inorder to help remo!e caron and other impurities that are present.

The additional allo#ing elements go either into the charge or, later, into the re-nedsteel as it is poured into the ladle.

The process

After the furnace is charged, electrodes are lo"ered close to the surface of themetal.

The current enters through one of the electrodes, arcs to the metallic charge, :o"sthrough the metal, and then arcs ac$ to the next electrode.

4eat is generated # the o!ercoming of resistance to the :o" of current through the

charge.

This heat, together "ith that coming from the intensel# hot arc itself, %uic$l# meltsthe metal. In another t#pe of electric furnace, heat is generated in a coil.

steel making handout

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