8/20/2019 Lect 4 Smelting123123

1/17

 A Closer Look at Iron Smelting

or Extractive Metallurgy

8/20/2019 Lect 4 Smelting123123

2/17

The Smelting Process

• Early smelting operations in Britain

involve a t!o step process" smelting in a

charcoal#$urning %urnace an then re%ining

in a %orge &to reuce non#iron content'(

• These re)uire consiera$le capital* ra!

materials &iron ore* !oo to make charcoal

 + later coal to make coke* limestone' an atransportation system to istri$ute the

proucts(

8/20/2019 Lect 4 Smelting123123

3/17

,istorical Timeline

-ate Technology./th c(BCE

Tools an !eapons mae %rom 0e inmeteorites $y smelting in $loomeries

./11 BCE 0e 2 charcoal !rought iron

.st c( BCE 3lest existing $last %urnace in China

.411 Steel prouction appeare in Europe

.516 0e 2 coke  cast iron &A( -ar$y'

/117 Top steel proucers" China* 8S* 9apan

8/20/2019 Lect 4 Smelting123123

4/17

Bloomery

•  A $loomery !as the earliest %orm o% a

smelter(

•Bloomery consists o% a heat resistantchimney 2 pipes at the $ottom %or air 2

!ay to remove prouct calle $loom

&reuce iron'(

•  Air is ae via natural ra%t or $ello!s

!hich re)uire po!er &e(g( :ater po!er'

8/20/2019 Lect 4 Smelting123123

5/17

Bloomery # /

• Process" ,eat $loomery $y $urning

charcoal or coke; !hen hot* a iron ore 2

more %uel 2 limestone(

• -uring the process* iron in the ore is

reuce as pure iron pieces %all to $ottom

o% chimney an !el together in a spongy

mass to %orm the $loom(

8/20/2019 Lect 4 Smelting123123

6/17

Bloomery # <

• The rest o% the ore &impurities' %orm the

slag( It also ens up at the $ottom o% the

chimney incluing $ecoming em$ee in

the $loom(

• To remove the slag an thus %urther puri%y

the iron prouct* the $loom is reheate an

then hammere(• The prouct o% this process is calle

!rought iron(

8/20/2019 Lect 4 Smelting123123

7/17

Charcoal an Coke

• Charcoal" =esiue le%t !hen !oo

&car$ohyrate' is heate in a$sence o%

oxygen &anero$ic' to rive o%% !ater an

other volatile components( The porousresiue is a$out 74> car$on an $urns

hotter an cleaner than !oo(

• Coke" =esiue le%t !hen coal is heate ina$sence o% oxygen &anero$ic' to rive o%%

!ater an other gases &,/* C,?* C3'(

8/20/2019 Lect 4 Smelting123123

8/17

Charcoal to Coke

• Clo! an Clo! p

8/20/2019 Lect 4 Smelting123123

9/17

Blast 0urnace

•  Again the re)uire components are iron ore*

%uel &originally charcoal'* oxygen or air an a

!ay to recover the prouct(

• Process" A iron ore an %uel %rom top an

air &the $last' %rom the $ottom resulting in

iron reuction occurring continuously

throughout the %urnace(• =euce iron an slag %all to the $ottom an

are recovere(

8/20/2019 Lect 4 Smelting123123

10/17

Blast 0urnace # /

• The process o% using coke instea o% charcoal

as the %uel !as %irst evelope an sustaine

$y A$raham -ar$y I in Coal$rookeale in

.516( This !as a maor contri$utor to theInustrial =evolution(

• This %urnace originally mae cast iron pots*

kettles* an later steam engine cyliners(• Later pig iron !as prouce(

8/20/2019 Lect 4 Smelting123123

11/17

Coke Iron

•  A secon $last %urnace !as $uilt in .5.4

!here !ork culminate in .54? &A( -ar$y

II' success%ully proucing iron $ars %rom

pig iron( This le to a huge expansion o%

the iron inustry(

• .5@7 + %irst iron rails

• .557 + A( -ar$y III starte $uiling the %irst

Iron$rige an complete it in .571(

8/20/2019 Lect 4 Smelting123123

12/17

The Pace o% Technology

• The transition to coke#$ase cast ironprouction %rom charcoal#$ase mallea$leiron prouction took over 41 years even as

%orests !ere eplete* ne! cast#irontechnologies !ere evelope an limitationsovercome" + Lack o% high )uality coal &i(e( lo! in S'

 + Lack o% high )uality coke

 + -eveloping more an ne! sources o% po!er 

 + =esistance to change to ne! technology

8/20/2019 Lect 4 Smelting123123

13/17

• The %irst -ar$y %urnace !as excavate

an is on isplay at Iron$rige(

• The %ollo!ing slie sho!s a moern $alst

%urnace(

8/20/2019 Lect 4 Smelting123123

14/17

http"!!!(pigiron(org(ukinex

(phpnavD%urnaceprocess

http://www.pigiron.org.uk/index.php?nav=furnaceprocesshttp://www.pigiron.org.uk/index.php?nav=furnaceprocesshttp://www.pigiron.org.uk/index.php?nav=furnaceprocesshttp://www.pigiron.org.uk/index.php?nav=furnaceprocess

8/20/2019 Lect 4 Smelting123123

15/17

Iron an its Alloys

0e 3xies 0e/3 C 2 Si* Mn* P* S impurities(ery $rittle &!hy calle FpigG iron'

Cast 0e />#?> C 2 .>#@> Si 2 Mn impurities(

Prouce $y heating pig iron toreuce P an S(

C Steel  /> C !ith Mn* S* P an Si

:rought0e

H 1(/4> C( ery mallea$le

 Alloy Steel Lo! C* $ut !ith ae Cr* M$* i* :

,SLA Microalloye* high strength* lo! alloy

8/20/2019 Lect 4 Smelting123123

16/17

Properties an 8ses o% Iron D

%&composition'

•  At least < types o% pig iron !ere prouce

in the early stages o% smelting( They i%%er

in > 0e* C* etc

 + :hite crue iron" most $rittle* not mallea$le*

very har* $right !hite crystals !hen

%racture(

 + Jrey crue iron" ark granular %ractures* notas har or $rittle* more easily shape

 + Black cast#iron" rough %ractures

8/20/2019 Lect 4 Smelting123123

17/17

E%%ect o% Iron Impurities on

Properties

C As >C increases* harness increases* $utmallea$ility ecreases(

S Causes hot iron to $e $rittle causing cracks

 limite integrity* !el %ailure(Si Leas to gray iron !hich is less $rittle*

pre%erre %or casting(

P Increases harness an strength i% 1(14> H>P H 1(/>( But K 1(/>* iron $ecomes$rittle an unsta$le at lo! T(

 Al Mainly impacts slag viscosity &%luiity'(