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The 973 Ext ract iv e Meta l lu rg y

ecture

The Meta l lurg ica l So c ie ty

of

AIME

The Linde Argon Oxygen Process for

Stainless Steel; A Case Study of

Major Innovation in a Basic Industry

W. A. KRIVSKY

The Lectur e t race s the development of the Linde Argon-Oxygen Pro ces s from its conception

in 1955 to its full scale and widespread util ization in the sp ecialt y s teel i ndustry on a world-

wide basis at the present t ime. The basic invention was derived from firs t principles of phys-

ical chemistry known to all third year college chemistry s tudents . I ts long saga of development

over a f if teen-year period required a grea t deal more; namely a corporation with tremendous

res our ces and more i mportant ly almo st boundless faith to continue in spite of some devast -

ating rev er sal s a sm all company with grea t vis ion and engineering ingenuity to evolve a

nontraditional proc ess for the manufacture of s tain less s teel which many lar ger companies

had despa ired of and a marketing effort which was able to do the alm ost i mpossibl e which was

to convince a basic industry such as s teel of the merit s of a revolut ionary new process s ig -

nificantly different in method of operation and ca pital re quire ments without being a part of

that industry it self and without means of proving the pro ces s i n-house . The developmen t of

the Linde Argon-Oxygen Pro ces s is a massi ve tr ibute to American i ndustry the dedication of

many of i ts m embe rs and the tremendous abili ty of different industries to work together in

a major development. The Lecture attemp ts as any good case his t ory should to general ize

from this specific case the lessons to be learned by industry by individual engineers and

scie ntis ts by government and the academic community in major proce ss innovation in a

basic industry. Such an i ncreas ed understanding leading to improved implementation of new

knowledge into major industry is crit ical ly important if the United States is to improve its

s tanding in international markets . Since the Linde Argon-Oxygen Process is an all-Amer-

ican developm ent its study should lead us to fuller understandi ng of both the unique adva nt-

ages our syste m provides for such innovation and means by which we may ac cele rate such

badly-needed developments in the future.

DR. WILLIAM A. KRIVSKY is president, Crucible Specialty Metals Div. , Colt

Industries , Syracuse, N. Y.

Dr . Kr iv sk y , wh o h o ld s h i s d o c to ra te (1 9 5 4 ) in p ro ces s meta l lu rg y f ro m MIT,

jo in ed Un io n Carb id e Co rp . th a t y ear an d as research meta l lu rg i s t an d l a te r man -

ager of metals research invented the Argon- Oxygen Process for s tainless s teel which

fo rms th e su b jec t mat te r o f th e EMD Lec tu re . He h o ld s th e b as ic p a ten t o n

th

process assigned to the Union Carbide Corp. A fter 1 959 he was associated with

Brush Beryll ium Co. as vice president and general mana ger; Continental Copp er

and Steel Industries as administrat ive vice president; and General Cable Corp. as

group vice president.

Dr. Krivsky has served on several technica l committee s of AIME and is a past

chair man of the Extractive M etallurgy Division. He has also served as a director of

TMS and is curre ntly an AIME director . In 1959 he was recipient of the Extrac tive

Metallurgy Division s Gold M edal, jo in tly with Dr. R. Schuh mann , for their contri-

b u t io n o n th e th erm o d y n amics o f co p p er smelt in g . In 1 9 6 5 h e ed i t ed th e b o o k

igh Temperature Refractory Metals b ased u p o n an in te rn a t io n a l sy mp o s iu m

wh ich h e o rg an ized an d ch a i red fo r th e AIME.

The 1973 Extractive Metallurgy Division Lecture was delivered on Feb, 28 at

the 102nd TMS-AIME An nual Meeting in Chicago.

M E T A L L U R G I C A L T R A N S A C T I O N S V O L U M E 4 , J U N E 1 9 7 3 - 1 4 39

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A

2 - grea t deal has been wri tten and spoken about the

effectiveness of basic i ndustrie s in the United States

in applying advanced technology to larg e scale meta l-

lurgical proc ess es. Arguments have been put forth

about the amount and type of fundamental research that

should be done, the methodology of transl atin g basic re -

sear ch in economical new pro ces ses, the role of the

Federal government in this endeavor, the educational

pro ces s which res ults in individuals who can accom-

plish this objective, and the various forms of organi-

zational alignments within corporations that s timulate

and make effective such effort. In spite of many diffe r-

ing views on these subjects , general agreement exists

on the fundamental principle which gives such gr eat

importance to the subject; namely, the corporation, the

industry, or the nation which makes most effective use

of technology will be the most competitive, the most

prosp erou s, and will thereby be capable of supporting

the highest s tandard of l iving for i ts memb ers.

In reaching general conclusions on such a compl ex

and vital issue, it has been useful in many fields to ex-

amine, in detail , many case his tories of specific in-

stances. We have available to us in the s teelmak ing

industry the rece nt example of the Linde A-O2 Decar bu-

rizati on Proce ss. Let us examine its origin, i ts devel-

opment, and its co mmerc iali zatio n and determ ine what

general l essons it teaches which will perm it us to more

effectively exploit our knowledge and technology in the

future.

THE LINDE AOD PROCESS TODAY

First of all, let us discuss the process itself. A

charge containing essentially all of the important al-

loying elements of the stainless steel composition to

be produced in their entirety is melted down in an

electric arc furnace. Fig. 1 shows such a heat being

poured from a furnace after slag-off. The molten steel

is then transferred by ladle to a separate refining ves-

sel which is similar to a Be ssemer converter with two

or mo re tuyeres in the bottom, Fig. 2. Oxygen is blown

through the molten bath admixed with varying amounts

of argon, with the ratio of argon to oxygen increasing

with time during the blow and finishing with pure argon

in man y cases, Fig. 3. Very small final additions of

alloying elements and deoxidizing elements are mad e

to the melt, Fig. 4, and the finished steel is tapped

directly fr om the vessel, Fig. 5.

This new duplex process replaces conventional stain-

less steelmaking which used only a single melting and

refining vessel; namely, the electric furnace. The sig-

nificant changes in practice brought about may be seen

by the comparison of the older conventional practice

and the AOD Process shown in Table I. In the conven-

tional practice the charge melted down in the electric

furnace in the production of a typical 18 pct Cr-8 pct

Ni grade could only contain about 4 pct Cr. If the extra

low carbon ELC) product was sought, even less chro-

mi um could be included in the charge. With the new

practice all the chr om iu m required in the final product

~ 18 pct) is charged into the furnace. In the conven-

tional

prac tice , the molten furnace charge was lanced

with pure oxygen to the end point of 3300~ and a car -

bon content of 0.02 pct. During this st ep appro xim ate ly

one-half of the ori ginal chromi um charged (4 pct) was

oxidiz ed into the slag, l eaving the met al with about a

1440-VOLUME 4 JUNE 1973

Fig. 1--Tapping an el ectri c furnace after melting of charge

only.

2 pct Cr content. In the Linde AOD Proc ess , blowing

the heat with varying A-O2 mixture s in a separ ate ve s-

sel is done to an end point of 3100~ and 0.03 pct C. It

should be noted that the temperature is about 200~

lower than at the conventional pra ct ice end point. Dur-

ing this step the chr omium content in the bath is about

16.5 pct Cr. In the conventional prac tic e following blow-

ing, reducing agent in the form of FeSi or FeCrSi was

added to the slag to reduce about one-half of the chro-

mium in the slag back into the bath (1 pct). This was

followed by a very large addition of low carbon fe rro -

chrome (15 to 17 pct) to the bath to reach final compo-

sition. In the Linde AOD Pro ces s, FeSi or FeCrSi is

added to the slag to recover about one-half of the oxi-

dized chromiu m (0.75 pct). Gener ally no additions of

low carbon ferrochromium are necessary and it should

be evident at this point that a major economic advantage

of the process is in the substitution of low cost high

carbon ferrochrome in the charge for the relatively

high cost low carbon ferroc hrom e in the heat f inishing.

Graphically, the prog res s of the chromium and carbon

during the two different pra ct ic es is shown in Fig. 6 for

the producti on of 304L sta inl ess st eel. It can be seen

from this f igure that there is roughly one order of mag-

nitude difference in the Cr-C relationship when blown

with A-O2 mixtures rather than with pure oxygen. This

is the real crux of the invention and the successful ap-

plication of high temperature physical chemistry to

steelmaking innovation.

METALLURGICAL TRANSACTIONS

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Fig. 2--Transferring hot metal to separate refining vessel.

Fig. 3--Argon-oxygen decarburization in refining vessel.

ORIGIN OF TH E PR O E SS

How did it all begin ? What was the ori gin of the i n-

vention and how was i t developed into the commercial

prac tic e we have today ?

I t a l l star t ed in 1954 at the Metals Re sea rch Labo ra-

tor ie s of the Union Carbide Corpora t ion in Niagara

Falls, New York, in quite an innocent manner and with-

out spec i f ica l l y at tempt ing to deve lop a new s t ee lmak-

t rig proc ess . Jus t pr io r to that t ime , R ichardson in

England had published a therm ody nami c study of the

re la t ionship of chromium to ca rbon in s ta in less s tee l

re f in ing in which he had c lass ica l ly equi l ibra ted ca rbon

monoxide-ca rbon d ioxide gas mixtures wi th Fe-Cr -C

mel ts . His resul ts wer e somewhat d i f fe rent than those

of Hl l ty and Craf ts publ ished ea r l ie r . The exper i menta l

method of Hilty and Crafts was substantia lly different

from that of Richardson in that they had blown small

induction furnace heats of Fe- Cr- C with oxygen, a t-

tempt ing to es tabl ish equi l ibr i um va lues for chromium

and ca rbon by approaching such va lues f rom both h igh

and low carbon contents. The present author set out to

resolve the difference in the two studies by extending

the range of Cr- C relati onshi p studied following the

genera l exper ime nta l me thod of Hi l ty and Cra f ts . The

init ia l work was done in a 100-pound induction furnace;

and i t became rapidly evident that , in a ttempting to est-

abl ish equi l ibr ium Cr-42 re la t io nships , i t was essent ia l ly

imposs ib le to achieve the i so the rmal condi t ions neces-

sar y becau se of the highly exot hermi c nature of the Cr- O

METALLURGICAL TRANSACTIONS

reac t ion . Some tenta t ive a t tempts were made to contro l

the exot herm ici ty of the reacti on by diluting the oxygen

with argon in the small furnace, and I t was immediately

noted tha t for any g iven chromium l eve l and te mpera -

ture , the ca rbon leve l was approximate ly an order of

magni tude lower than those predic ted by the ea r l ie r

work of e ith er R icha rdso n or Hilty and Crafts

At th is poin t a review of the bas ic phys ica l chemis-

try of the system revealed what was taking place and

began to lead us in the proper d i rec t ion for the inven-

Table I. Stainless Staelmaking Conventional vs Argon Oxygen

Conventional A-O2

1.) Meltcharge in electricfurnace

a) 4 pet Cr charge normal;less

Cr charged for ELC grades

2.) Lance with oxygen;end point

3300~

2 pet Cr

0.02 pet C

3.) Recover ~ of Cr (1 pct) in slag

with FeCrSior FeSi add'n.

4.) Add 15 to 17 pct Cr as low

carbon FeCr o final specifica-

tion

Final Composition:

Cr-18.5 pet

C-0.02 pet

Melt charge in electric furnace

a) 18 pct Cr charged even for ELC grades

b) deslag melted charge transfer charge; o

AOD vessel

Blowwith oxygen-argonmixture;end point

3100~

17 pet Cr

0.03 pet C

Recover0.75 pct Cr from slag. Pure argon

injection

Nolowcarbon FeCr addition necessary

Final Compositon:

Cr-18.5 pct

C-0.OI pet

VOLUME 4, JUNE 1973-1441

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Fig. 4--Adding final additions to refining ves sel after blowing.

t i o n o f t h e L i n d e AO D P r o c e s s . T a b l e I I s u m m a r i z e s

t h e b a s i c p h y s i c a l c h e m i s t r y o f t h e L i n d e A OD P r o c e s s

a n d b r i n g s u s t o a fu l l u n d e r s t a n d i n g o f t h e d i f f e r e n c e s

b e t w e e n c o n v e n t i o n a l p r a c t i c e a n d t he n e w p r o c e s s . I t

i s c l e a r f r o m t h i s T a b l e t h a t i n c o n v e n t i o n a l s t e e l m a k -

i n g t h e p r e s s u r e o f c a r b o n m o n o x i d e i s 1 a t m , s i n c e

a l l t h e o x y g e n b lo w n i n t o t h e b at h i s c o n v e r t e d t o e s -

s e n t i a l l y c a r b o n m o n o x i d e a s i t e x i t s t h e s y s t e m a n d

t h e r e f o r e , f o r a g i v e n t e m p e r a t u r e , t h e e q u i l i b r i u m

c a r b o n c o n t e n t w i l l b e p r o p o r t i o n a l t o t h e t h r e e - f o u r t h s

p o w e r o f th e c h r o m i u m c o n t e n t . I n t h e L i n d e A O D P r o -

c e s s t h e c a r b o n c o n t e n t w i l l b e a f u n c t i o n o f both the

t h r e e - f o u r t h s p o w e r o f t h e c h r o m i u m l e v e l a n d t h e r e -

s u l t in g p a r t i a l p r e s s u r e o f c a r b o n m o n o x i d e

after

d i l u -

t i o n w i th a r g o n w h i c h p a s s e s t h r o u g h t h e b a t h u n c h a n g ed .

T a b l e I II i l l u s t r a t e s t h e e f f e c t o f t h e r a t i o o f a r g o n t o

o x y g e n i n t h e i n p u t g a s s t r e a m o n th e c a r b o n c o n t e n t

r e d u c t i o n r e l a t i v e t o c o n v e n t i o n a l p r a c t i c e . T h e r e -

s u l t i n g c a r b o n m o n o x i d e p r e s s u r e , w h i c h c o n t r o l s t h e

c a r b o n c o n t e n t , i s d e r i v e d f r o m t h e c o n s i d e r a t i o n t h a t

w h i l e a m o l o f a r g o n g o e s t h r o u g h t h e b a t h u n c h a n g e d ,

a c o r r e s p o n d i n g m o l o f o x y g e n r e s u l t s i n t h e f o r m a t i o n

o f 2 m o l e s o f c a r b o n m o n o x i d e . T h e s e t h e o r e t i c a l c o n -

s i d e r a t i o n s a r e n ow b o rn e o u t in p r a c t i c e l i t e r a l l y

h u n d r e d s o f t i m e s d a i l y a r o u n d t h e w o r l d . I t s h o u l d

n o t b e o v e r l o o k e d a t t h is p o i n t t ha t t h e P r o c e s s h a s

a n a l t e r n a t i v e m e t h o d o f u t i l i z a t i o n ; n a m e l y , t h a t th e

s a m e C r - C r e l a t i o n s h i p c a n b e a c h i e v e d a t s i g n i f i -

c a n t l y l o w e r t e m p e r a t u r e s t h a n in c o n v e n t i o n a l p r a c -

t i c e .

F u r t h e r w o r k i n t h e l a b o r a t o r y w a s t h e n c o n t i n u e d

t o f u l l y v e r i f y w h a t h a d b e e n f o un d i n i t i a l l y a n d, f o r

t h e f i r s t t i m e , c o n s c i o u s l y d i r e c t e d t o t he p o s s i b l e

d e v e l o p m e n t of a ne w s t e e l m a k i n g p r a c t i c e . T h e r e

w e r e s e v e r a l e c o n o m i c f a c t o r s t h a t g a v e i m p e t u s t o

t h e c o m m e r c i a l e x p l o i ta t i o n o f t h e s e l a b o r a t o r y f i n d -

i n g s a t th e t i m e . I t h a d b e e n k n o w n f o r s o m e t i m e t h a t

t h e d e c a r b u r i z a t i o n o f e x p en s i v e , n i c k e l - b a s e a l l o y s

c o u l d b e e n h a n c e d b y t h e u s e o f a v a c u u m . E x t e n d i n g

s u c h a p r a c t i c e t o s t a i n l e s s s t e e l w a s c o n s i d e r e d

t o t a l l y i m p r a c t i c a l b e c a u s e o f t h e l o w c o s t of t h e p r o d -

u c t a n d i t s s c a l e o f m a n u f a c t u r e . T h e e f f e ct o f t h e

p r e s e n t p r o c e s s w a s t o d e v e l o p a c r u d e v a c u u m w i t h -

o u t t h e u s u a l e q u i p m e n t ; i t w a s a f f e c t i o n a t e l y l a b e l e d

a p o o r m a n ' s v a c u u m . S i m u l t a n e o u s l y t h e r e w a s a

g r o w i n g m a r k e t d e m a n d f o r th e e x t r a l o w c a r b o n ( E L C )

g r a d e s o f s t a i n l e s s s t e e l s , b u t t h e p r o d u c t i o n c o s t s

@

F ig . 5 - - Ta p pin g f in i s h ed s t e e l f r o m r e f in in g v e s s e l .

Convent ion al Argon Oxygen

Pract ice Pract ice

0.5

0.2

0.1

0.05

x

-- [ Oxygen Blow ~rgon-Oxygen

[) O / Blow

i >

I y X

\

- - / \

Finish-Using Major / X

0.02

0.01

0.005

Additions of Fe Cr Si, Finish-Using

LC-Fe Cr, etc Minor Additions

of Fe Cr Si, Fe Si, etc.

0 4 8 12 16 20

Chromium

Fig. 6--Conventional vs Argon-oxygen practice for 302L.

w e r e n e a r l y p r o h i b i t i v e b e c a u s e o f t h e e f f e c t of t h e

h i g h f i n i s h i n g t e m p e r a t u r e s o n r e f r a c t o r y l i f e a s w e l l

a s t h e p o o r r e p r o d u c i b i l i t y o f t h e c o n v e n t i o n a l p r o -

c e s s . T h e a r g o n d i lu t i o n p r i n c i p l e a p p e a r e d t o a f f o r d

1442-VOLUME 4, JUNE 1973 METALLURGICAL TRANSACTIONS

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Tab l e I I . C he m i s t r y o f A r gon- O xy gen S t a i n less S tee l m ak ing

C r 3 0 4 ( s ) + 4 C 3 C r + 4 C 0 ( g )

- a 3 . 4 a 4 .

K t - C r

Poa / _c

a c r s O ,

K~ = (~ C_0~P'r I( ~ CD

C o n v e n t i o n a l s t e e l m a k i n g

% C = I / K a ( % C r ) 3 14

A - O a s t e e l m a k i n g

C_ = 1/Ka (

C_r)

3 / 4 p

Tab l e I I I .

C a r b o n C o n t e n t a s a F u n c t i o n o f A r g o n - O x y g e n R a t i o v C o n v e n t i o n a l

rac tice

C o n s t a n t C h r o m i u m L e v e l ; C o n s t a n t T e m p e r a t u re

R e d u c t i o n i n

A / O 2 I n p u t P c o A t m C a r b o n L e v e l, p c t

1 2 3 3 -~

2 1 5 0

4 -~ 66 2

8 -~ 8o

1 8 ~ 9 0

a n i d e a l m e t h o d fo r t h e m a n u f a c t u r e o f s u c h g r a d e s .

A n o t h e r s i m u l t a n e o u s d e v e l o p m e n t o f t h e t i m e w a s

t h e r i s i n g u s e o f t h e B O F p r o c e s s i n t h e U n i t e d S t a te s

w h i c h w a s l e a d i n g to s i g n i f i c a n t i n c r e a s e s i n o x y g e n

p r o d u c i n g c a p a c i t y w h i c h , f o r r e l a t i v e l y m i n o r a d d i -

t i o n a l c a p i t a l i n v e s t m e n t , c o u l d p r o d u c e v a s t q u a n t i t i e s

o f a r g o n a t l o w e r c o s t t h a n p r e v i o u s l y . A l l t h e s e c o n -

s i d e r a t i o n s l e d u s t o p u r s u e t h e d e v e l o p m e n t o f t h e

L i n d e A O D P r o c e s s . T h e o r i g i n a l w o r k to r e s o l v e

t h e m i n o r d i f f e r e n c e s b e t w e e n t h e r e s u l t s o f R i c h a r d -

s o n a nd t h o s e o f H i l t y a n d C r a f t s w a s n e v e r c o m p l e t e d .

T h o s e d i f f e r e n c e s h a d a d m i r a b l y s e r v e d t h e i r p u r p o s e

S c a l e u p o f t h e p r o c e s s w a s s u c c e s s f u l l y a c c o m -

p l i s h e d f r o m t h e 1 0 0 - po u n d f u r n a c e t o a o n e - t o n a r c f u r -

n a c e . V e r i f i c a t i o n o f t h e s m a l l e r s c a l e h e a t s w a s e x -

c e l l e n t a nd fu r t h e r w o r k o n s c a l e - u p p r o c e e d e d w i t h

g r e a t c o n f i d e n c e . I t s h o u l d b e c l e a r l y u n d e r s t o o d t h a t

t h i s i n i t i a l w o r k w a s b e i n g d o n e f o l l o w i n g th e c o n v e n -

t i o n a l p r a c t i c e r i g h t i n t h e e l e c t r i c a r c f u r n a c e b u t

m e r e l y s u b s t i t u t i n g A - 0 2 m i x t u r e s f o r th e p u r e o x y -

g e n n o r m a l l y i n je c t e d . V a r i o u s t r o u b l e s w e r e e x p e r i -

e n c e d w i t h s p l a s h i n g of t h e b at h a n d r e f r a c t o r y e r o -

s i o n e v e n i n t h e o n e - t o n t e s t s b u t , g e n e r a l l y s p e a k i n g ,

i t w a s e x p e c t e d t h a t s u c h p r o b l e m s w o u l d b e o v e r c o m e

w i t h i m p r o v e d a n d m u l t i p l e l a n c e s a s h e a t s i z e i n -

c r e a s e d . T h e n e x t s t e p i n d e v e l o p m e n t u t i l i z e d t h e

3 t o n a n d 5 t o n f u r n a c e s o f t h e H a y n e s S t e l l i t e C o m p a n y ,

t h e n y e t a d i v i s i o n o f U n i o n C a r b i d e . S u c c e s s w a s a g a i n

d e m o n s t r a t e d b u t a g r e a t d e a l o f d i f f i c u l ty w a s e x p e r i -

e n c e d i n m a k i n g th e l a n c i n g p r a c t i c e e f f e c t i v e . L a n c e s

w e r e e x p e r i m e n t a l l y c o a t e d w i t h j u s t a bo u t e v e r y k n ow n

r e f r a c t o r y , a n d s i n g l e an d m u l t i h e a d e d la n c e s w e r e a t -

t e m p t e d p o s i t i o n e d a b o v e t h e b a t h . I t w a s f o un d t h at t h e

a r g o n , a t l e a s t , h a d t o b e i n j e c t e d i n t o th e b a t h a n d w a s

n o t e f f e c t i v e w h e n bl o w n o n t h e s u r f a c e . F u r t h e r , t h e

r e s u l t s s h o w e d th e i m p o r t a n c e o f g e t t in g g a s d i s p e r s a l

t h r o u g h o u t t h e b a t h f o r i f t h e b e n e f i c i a l d i l u t i o n p r i n -

c i p l e f u n c t i o n e d o n l y l o c a l l y , t h e e f f e c t o n t h e t o t a l

b a t h w a s m i n i m a l .

F A I L U R E O F T H E F I R S T P R O D U C T I O N

A T T E M P T S

U n i on C a r b i d e , n o t b e i n g a s t a i n l e s s s t e e l p r o d u c e r ,

h a d g o n e a b o u t a s f a r a s i t c o u l d g o a l o n e i n th e s c a l e -

u p e f f o r t s . I t o b v i o u s l y n e e d e d a p a r t n e r w i t h l a r g e r

f u r n a c e s i n o r d e r t o b r i n g t h e p r o c e s s t o f u l l c o m m e r -

c i a l s c a l e . A l o n g s e a r c h o f a l l t h e s t a i n l e s s s t e e l p r o -

d u c e r s f o l l o w e d , w i t h v e r y d i s c o u r a g i n g r e s u l t s i n g e n -

e r a l . F o r v a r i o u s r e a s o n s , n e a r l y e v e r y c o m p a n y d e -

c l i n e d to p a r t i c i p a t e i n t h e f u r t h e r d e v e l o p m e n t u n t i l

t h e J o s l y n S t a i n l e s s S t e e l C o m p a n y w a s a p p r o a c h e d .

H e r e , i n s p i t e o f t h e f a c t t h a t t h e y w e r e o n e o f t h e

s m a l l e r p r o d u c e r s w i t h ou t t h e t e c h n i c a l a n d f i n a n c i a l

r e s e r v e s o f s o m e o f t h e i r l a r g e r c o m p e t i t o r s , t h e y

n e v e r t h e l e s s h a d t h e c o u r a g e a n d f o r e s i g h t t o p r o c e e d .

I n 1 9 60 U n i o n C a r b i d e a n d J o s l y n s i g n e d a j o i n t d e v e l -

o p m e n t a g r e e m e n t .

T h e f i r s t t e s t s c o n d u c t e d a t J o s l y n o n a 1 5 t o n s c a l e

t u r n e d o u t t o b e n e a r l y a b s o l u t e , d i s m a l f a i l u r e s . A l -

t h o u g h a g r e a t d e a l o f a t t e n t i o n h a d b e e n p a i d t o th e

l a n c e p r o b l e m a n d v a r i o u s m e t h o d s , i n c l u d i n g t h e u se

o f t h r e e f i r e c l a y - s l e e v e d l a n c e s p o s i t i o n e d a b o v e t h e

b a t h , w e r e t r i e d , n o s u c c e s s f u l h e a t s w e r e p r o d u c e d .

V e r y c a r e f u l a n d d e t a i l e d a n a l y s i s o f t h e r e s u l t s i n d i -

c a t e d t h a t w h i l e l o c a l a c t i o n o f t h e a r g o n d i l u t io n p r i n -

c i p l e n e a r t h e p o i n t o f i n j e c t i o n w a s e f f e c t i v e , t h e n e t

e f f e c t o n t h e e n t i r e b a t h , a f t e r i t h a d h o m o g e n i z e d f o l -

l o w i n g t h e b l o w , w a s i n c o n s e q u e n t i a l . L a r g e s c a l e

t e s t i n g w a s r e g r e t f u l l y a b a n d o n e d b u t w o r k w a s c o n -

t i n u e d o n a l a b o r a t o r y s c a l e . T h i s w o r k a g a in c l e a r l y

i n d i c a t e d t he f e a s i b i l i t y o f t h e p r o c e s s i f t h e a r g o n

c o u l d b e d i s t r i b u t e d t h r o u g h o u t th e e n t i r e b a t h . T h e

p r o c e s s n e v e r f a i l e d t o p e r f o r m u n d er s u c h c i r c u m -

s t a n c e s . C o n v e r s e l y , w h e n e v e r th e b a t h d i a m e t e r w a s

l a r g e r e l a t i v e t o s u r f a c e i n j e c t i o n d e v i c e s , n o d i s c e r n -

i b l e b e n e f i t w a s a c h i e v e d i n t h e b a t h a s a w h o l e .

R E C O V E R Y F R O M F A I L U R E

A r m e d w it h t h i s m o r e c l e a r u n d e r s t a n d i n g , U n i o n

C a r b i d e a n d J o s l y n m a d e t h e h i s t o r i c d e c i s i o n t o b u i l d

a re f i n i n g v e s s e l a p a r t f r o m t h e e l e c t r i c a r c f u r n a c e .

T h i s f i r s t s u c h v e s s e l w a s o n l y -~ t on i n c a p a c i t y a n d

p r o v i d e d f o r t h e t o p b l o w i n g o f o xy g e n a n d t h e b o t t o m

i n j e c t i o n o f a r g o n t h r o u g h a t u y e r e . T h e r e s u l t s w e r e

d r a m a t i c a l l y f a v o r a b l e a n d s u p p o r t e d a l l t h e l a b o r a t o r y

s c a l e w o r k p r e v i o u s l y d o n e.

H o w e v e r , t h e i d e a o f a p p l y in g th e a r g o n d i l u t io n p r i n -

c i p l e d i r e c t l y i n t h e e l e c t r i c f u r n a c e d i e d v e r y s l o w l y .

T h e r e w a s o b v i o u s r e l u c t a n c e t o d e v e l o p a p r o c e s s

t h a t w o u ld c r e a t e a n o t h e r s t e p i n t h e m a n u f a c t u r i n g

p r o c e s s a n d t h a t w o u ld r e q u i r e a n a d d i ti o n a l c a p i t a l

i n v e s t m e n t . W h a t w a s n o t r e a l i z e d a t t h i s p o in t in

t i m e , w a s t h a t t h e s e p a r a t e r e f i n i n g v e s s e l w o u l d

dou le the s t e e l o u t p u t o f a g i v e n f u r n a c e . S i n c e i t s

c o s t w a s o n l y a s m a l l f r a c t i o n o f t he c o s t o f a n a d d i -

t i o n a l e l e c t r i c f u r n a c e , i t r e p r e s e n t e d a v e r y i n e x p e n -

s i v e m e a n s o f i n c r e a s i n g s t e e l m a k i n g c a p a c i ty . N e v e r -

t h e l e s s , f o r t y - f i v e a d d i t i o n a l 1 5- t on h e a t s w e r e t r i e d i n

t h e a r c f u r n a c e , w h i c h , in s p i t e o f v a r i o u s c o n f i g u r a -

t i o n s o f l a n c e s , t o t a l l y f a il e d t o g i v e a n y b e n e f i c i a l r e -

s u l t s c o m p a r e d t o th e -~ t o n s e p a r a t e v e s s e l .

A s a r e s u l t o f t h e s e e f f o r t s , t h e t w o c o m p a n i e s p r o -

c e e d e d w i t h th e d e s i g n o f a 1 5 - to n s e p a r a t e r e f i n i n g

v e s s e l . A f t e r m u c h e x p e r i m e n t a t i o n w i t h t o p a n d b o t -

M E T A L L U R G I C A L T R A N S A C T I O N S V O L U M E 4 , J U N E 1 9 7 3 - 1 4 4 3

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tom inj ect ion of one or both gases, use of porous bot-

toms , and wi th var ious tuyere des igns , there f ina l ly

emer ged in 1967 a s imple m ult iple tuyere which com-

bined both gases in the inject ion. Fig. 7 is a photo-

graph of this ea rly uni t which on October 24, 1967 pro -

duced the f i r s t fu l l heat o f s t a in less s t ee l ever com-

pletely refined, f inished, and poured direct ly into

molds ut i l izing the Linde AOD Pro ces s . This was a

heat of type 304 ELC and its log of manufacture is

shown in Table IV. Two addi t ional heats were pr o-

duced in this uni t with equal succes s . The t ide in the

for tunes o f development were s imul tane ous ly tu rn ing

for an over sea s company, also working with Linde,

which repor ted s imi l ar s uccess work ing in an 8- ton

separa te ref in ing vesse l . Noting the add i tional bene-

ficial effect of the Ltnde AOD Process as a means to

low-cos t cap i t a l inves tment fo r add i t ional s t ee lmaking

capaci ty as wel l as a lower operat ing cost pract ice,

Jos lyn made the deci s ion to bu i ld a fu l l commerc ia l

ins ta l l a t ion based on the argon d i lu t ion pr incip le and

separa te mel t ing and ref in ing vesse l s . Th i s un it was

bui l t earl y in 1968 and is shown in Fig. 8. I t featur ed

two tuyeres instal led on the bot tom back s ide of the

vessel which emerged above the bath when the vessel

was rotat ed for char ging, sa mpling, holding or tapping.

The ves se l was 9 ft in diam et er and 1389 ft high. Duri ng

1968 some one hundred heats were made in this uni t

from which the fol lowing general conclusions were

reached:

1) Proce ss economies were es tab l i shed beyond any

quest ion.

2) The charge to the electr ic furn ace could be made

up of the lowest cost chromium and nickel uni ts with-

ou t any res t r i c t ion on s tar t ing carbon or s i l i con l evel s .

3) Recovery of chromium was very h ig h--approxi -

mate ly 97 pct as was to ta l meta l l i cs .

4) Si l icon usage to rec over oxidized meta ls was re-

duced by 40 pct.

Fol lowing this c ampaign, Jos lyn modified this f i rs t

p roduct ion vesse l , Fig. 9 , and conver ted it s en t i re

melt shop to 100 pct AOD Pr ac tic e in July 1969. By

December of that year they were able to report the

resul ts of 1300 heats to the Electric Furnace Confer-

ence . The des ign pr incip le s used in th i s Jos lyn pro-

duct ion uni t are the basis of every AOD instal lat ion

current ly in use throughout the world, ranging in s ize

from 5 to 100 ton. Table V su mma riz es the major eco-

nomic advantages of the fu l ly commercia l i zed proce ss .

In add i t ion to the a l re ady-d i scus sed ab i l i ty to u t i l i ze

very l arge quant i t i es of the lowes t cos t raw mater ia l s

in the char ge almos t without l imita t ion and with ver y

high yields , thereby mi nimi zin g the use of expensive

f in i sh ing addi t ions , the p rocess g rea t ly in crea ses the

product iv i ty o f an e lec t r i c fu rnace . One arc fu rnace

plus an AOD ves sel has the prod uct ivi ty of two arc

furn ace s operated convent iona l ly. Since an AOD ves sel

i s s ign i f i can t ly l ess expens ive cap i t a l -wise than a sec-

ond arc fu rnace , the combinat ion i s the mos t eco nomi-

cal method to increa se capaci ty . Opera t ing cos t com-

par i sons wi th convent ional p rac t i ce vary in deta i l f rom

9 instal lat ion to insta l lat ion but gene ral l y speaking i t

may be sa id tha t the cos t o f opera t ing the ref in ing ves -

sel is more than offset by the savings in raw m ate ria ls

and the el imi nat ion of the ref ining and finishing s teps

f rom the e lec t r i c arc fu rnace . Desu l fur iza t ion i s ac-

complished rapidly and effect ively with a desulfurizing

1444-VOL UME 4 JUNE 1973

Fig. 7 --F irst 15 -ton refining vessel.

Table IV. Log of First Complete Stainless AO D He at October 24 1967

304L Time min Pet C Pct Cr ppm 02 ~

B/4tap -4 0.290 18.08 600 3140

B/402 6 0.259 18.02 230 2990

~ep 1 28 0.084 16.99 560 3160

~ep 2 46 0.033 16.46 800 3130

argon 51 0.027 16.46 660 3100

addns. 58 0.021 17.60 390 2980

product - 0.008 18.62 170 -

Fig. 8--Original Joslyn production unit.

Fig. 9--Final Joslyn production unit.

METALLURGICAL TRANSACTIONS

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T a M s V C~mme~clalA d v a nt a g es M t h e A O D Process

1.) Lower Cost Materials

-No pract ica l l imi ta t ions on s ta r t ing ca rbon conten ts

-Alm ost completely e liminates expensive low carbon chrom ium units

-Readily adaptable to new materia ls

2.) Sigoif icanfly increased yield o f metallic e lemen ts

3.) Greater Productivity

-On e arc furnace plu s AO D vessel equals two tim es arc furnace ou tput

-AO D vessel signif icantly less expensive th an a secon d arc furnace

4.) Operating Costs

-Savings of e liminating the te l ruing and f inishing stages from the arc furnace

more than of f se t the ope ra ting cos t o f the AOD

5.) Desnlfurization

-7 to 10 rain to slag off , add desulfuriz ing slag and s tir

6.) Lead Residuals

-Ro utine removal of lead to below 0.007 pc t

7.) Quality

-Cleaner, mo re reproducible , mo re easily mac hined steel

TaM e V I AO D Ins tal l at ions in the U S

Vessel

Capacity

Com pany S ta r tup Da te Tons

Arm co Steel Corp./Advanced Materia ls Div. 1/71 35

Baltimore, Maryland

Baldwin-l.Jma-Hamihon Corp. 8171 18

Standard Steel Division

Burn ham , Pennsylvania

Babcock and Wilcox Mid. 1973 25

Beaver Falls, Pennsylvania

Cabot Corporation /Stellite Division 1170 5

Kokom o, Ind iana

Carpenter Technolo gy Corp. 1172 15

Reading, Pennsylvania

Colt Industries, Inc./Crucible Stainless Steel Div. 3/7 2 100

Midland, Pennsylvania

Eastern Stainless Steel Co 11/70 5 0

A Division of EASCO Corp.

Baltimore, Maryland

Eleetralloy Corporation 9/70 17

Off City, Pennsylvania

International Nickel Co., Inc. 10/71 38

Hun tingto n Alloy Products Div.

Hun tingto n, West Virginia

Jessop Steel Co. 10/71

20

Washington, Pennsylvania

Jones and Laughlin Steel Corp. 12/71 70

Stainless and Str ip Division

Detroit, Michigan

Jos lyn Mfg . and Supply Co. 4 /68 17

Joflyn Stainless Steels Div.

Fort Wayne, Indiana

United States Steel Corp ./South Works 12171 100

Sout h Chicago, I llinois

s l a g a n d a r g o n a g i t a ti o n . L e a d is r o u t i n e l y r e m o v e d t o

b e l o w t h e 0 . 0 0 7 p c t le v e l . Q u a l i ty o f the s t e e l p r o d u c e d

i s f a r m o r e r e p r o d u c i b l e t h a n in c o n v e n t i o n a l p r a c t i c e

e s p e c i a l l y i n t h e E L C g r a d e s a n d i s s u b s t a n t i a l l y

c l e a n e r a n d m o r e f r e e l y m a c h i n in g .

E X P L O I T T I O N O F T H E J O S L Y N

S U C C E S S

It m u s t b e r e m e m b e r e d t h at U n i on C a r b i d e C o r p o r

ation is not a stainless steel pro duc er and the out

s t an d i ng s u c c e s s a t J o s l y n n e e d e d t o b e r e p e a t e d m a n y

m o r e t i m e s b e f o re t he p ro j ec t w o u l d b e a c o m m e r c i a l

success for Union Carbide. Prac tica lly every major

stainless s teel producer in the world was contacted.

With the cooperation of Joslyn demonstr ations were

arranged for various companies at Fort Wayne. Sav-

ings calculations were made for every potential l icen-

see under l i te ral ly thousands of local conditions and

proce ss a l ternat i ves . Ques t ions of fur ther scale-up

and product quality had to be answered. Prospec ts

were enabled to take Joslyn-produced AOD ingots

finish them in their own mill s evaluate and test

marke t them. In certain case s Union Carbide even

arranged to have the 15-ton test vessel at Joslyn

shipped to various prospects so that they might ac-

tually carr y out their own tests . In spite of local dif-

f iculties in accommodating the vessel this prog ram

was highly developed and extre mely successf ul in

convincing prosp ects to obtain licenses to the proce ss.

The second licensee to the process in the United States

was E lect rallo y in September of 1970; the f irs t foreign

lic ense e was Il lsa Viola in Italy in July of 1970. The

final tributes to Llnde and Union Carbide marketing

effor ts m ay be se en in Table VI and Table VII which

resp ect ivel y lis ts U. S. and foreign licen sees. During

1 9 7 3

Union Carbide expects 50 pct of the stainless

T a M e VII OverseesA O D Instellatiom

Vessel

Capacity

C o m p a n y S t a r tu p D a t e T o u s

Aves ta Jemwerks AB/Axe l Johnson and Co. 6 /73 60

Avesta , Sweden

Boschg otthardshutte 10173 18

Siegen, W. German y

British Steel Corp./Panteg Works 11/71 60

Ponty pool, W ales, U. K.

British Steel Corp./Stuckshridge Works 7/72 15

Stucksbridge, U. K.

FIAT , Sp. A. 1175 70

Torino, I ta ly

llssa Viola 7/70 22

Pont St. M artin, I ta ly

IMI Alloy Steels Ltd. 3/71 8

Somercotes, U. K.

Nippon Metal Indu stry Co. 7/72 75

Kinuura, Japan

Nippon Metal Indu stry Co. 11/71 55

Sagamihara, Japan

Olarra S.A. 10172 14

Bilbao, Spain 7173 10

Ro therha m Stainless and Nickel Alloys, Ltd. 11171 8

Rothe rham , U. K.

South ern Cross Steel 9172 25

Middelburg, South A frica

Spartan Steel and Alloys Ltd. 10/71 8

Birmingham, U. K.

Temi/Fm is ide r Group 8172 60

Temi , I ta ly

M E T A L L U R G I C A L T R A N S A C T I O N S V O L U M E 4 , J U N E 1 9 7 3 - 1 4 4 5

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ste el prod uced in the U. S. will be by mea ns of AOD

and that add itio nall y 625,000 ton will be produ ced

over s eas .

THE PURSUIT OF PATENT

PROTECTION

Obviously, the marketing effort had to be based on a

very s trong patent s tructure and process know-how.

The struggle for patent coverage was nearly as epical

as was the proc ess development his tory. The author

original ly f iled patent applica tions on behalf of Union

Carbi de on June 27, 1956. There followed a te n-y ea r

campai gn with the U.S. Patent Office which finall y cul-

minated on May 24, 1966 in the issuance of the basic

patent af ter severa l in ter ference and appeal proce-

dures were successfu lly overcome . The tenacity of

the Union Carbi de s patent counsel was ex trem e but

turne d out to be highly rewarding since the basic patent

has now ten more ye ars to run, where as had it been un-

contested and issued quickly it could well be expiring in

the next year or two, just about the time the process it-

se l f had been comm ercia l l y fu l ly subs tant ia ted . Fur ther ,

an improvement patent was granted in 1962 which basic-

ally related to the sequencing of various gas mixtures

for optimum result s during the refining proc ess.

L E S SO N S F R O M TH IS E V E L O P M E N T

It is a great pleasure to able to recount the long and

arduous sa ga of an ultimatel y overwhelming success

stor y, e spe cia lly when one has had a par t in it. This,

however, is not the main purpose; far more important

at this point is what we can learn from this experience

for our future mutual benefit . I t is believed that there

are many lessons to be learned here concerning tech-

nical innovation which affect many cla sses of individ-

uals .

For the Individual Researcher

1) The les son taught here is that of the extre me i m-

port ance of looking for the unexpe cted or the unusual

in any research work and the total acceptance of the

res ear ch data. This may sound elem enta ry but i t is

not always easy to do as a young, unknown researcher

when faced with apparent contradictions with the pub-

lished word of far more well-known and respected in-

ves t igators . In th is case , the markedly d if ferent re-

sults obtained in the very firs t argon tests from those

of the ea rly Hilty and Crafts and Richardson studies

could have been ascribed to some mysterious and un-

known experimental error and the total development

could have been lost right at that point.

2) All unexpected results can be understood ulti-

matel y in te rms of basi c theory if a sufficient effort

is made. This extremel y important step is highly pro-

ductive of inventions and must be thoroughly pursued.

In this par tic ula r ca se, going back to fundamental

physical chemistry led to a highly important new pro-

cess which would have not been reached had not this

step been comple tely executed.

3) Regar dless of the scientif ic nature of resear ch

work, the researcher must s tr ive to understand the

pract ic al and commercia l environment of the sys tem

he is s tudying. In the present case it was not the ortg-

inal intent of the work to invent a better process to

produce s t a in less s teel - - as has a l rea dy been said the

work was pr im ar i l y in tended to ra t ional ize d isag ree-

ing data between two sepa rate investigations. Fortu-

nately sufficient information had been lear ned about

stain less s t eel melting problem s and the impact of

large scale oxygen plants to per mit recognition of the

potential importance of the proce ss. Without this

knowledge, the development of a co mmer cia l proce ss

could have been totally missed at a very early s tage.

4) Abiding persi s ten ce and tenacity is absolutely

requi red if one is going to evolve abstrac t rese arc h

resu lts into comm erci al development. There is a t ime

during this period when the individual res ear che r, and

only the individual re sea rch er, has any idea at all of

the co mmer cia l s ignificance of that which has been

discov ered. He must be able to convince others for

the necessar y suppor t and re ject any d iscouragement

until the work is complete.

For the Educators in the Metallurgical

Profess ion

1) Tradi t ional ly , par t ic u lar ly in recent years , i t i s

beli eved that an excel lent job has been done in our

metal lurg ical c ur r icula of teaching fundamental pr in-

ciples of physics , chemistry, and mathematics and

their a pplications to metallur gy. I t is definitely be-

lieved that this type of training is the best suited to

pr epa re a student for making a contribution to his

profess ion .

2) I t is believed that me tall urgic al education would

benefit from greater depth in teaching of the engineer-

ing princi ples involved in metallu rgica l proces sing.

This development nearl y f loundered on the design of

the ref inin gvess el; and had individuals had stron ger

backgrounds in heat and fluid flow associated with

high temperature p roces ses , i t i s bel ieved that design

solutions would have been reached more direct ly. This

is in no way meant to mitigate the significant ingenuity

that was demonstrated in the final design solution. It

is only to say that teaching engineering technology ap-

plied to high temperature processes would be highly

productive and has not been done in metal lurgi cal edu-

cation to the same extent as has been done in the case

of phys ical chemi s t ry .

3) In teaching principl es and their application, the

s imultaneous teaching of so-c al led descr ip t i ve courses

concerning the hi s tor ica l production of the various

metals has n ecessa r i ly been s ignif icant ly reduced.

Yet to make a contribution in the real world one must

know and understand the current s tatus; some means

must be provided to fami lia riz e the s tudent with the

curren t s tate of the art . I t must be reme mbe red that

there is a time in the development sequence when only

the individual re sea rch er can know what he real ly has.

Unless he can relat e i t re adil y to the real world, he

will have an almo st impossibl e task of convincing

others as well as himself that he should persis t . He

cannot exist in a vacuum of knowledge concerning

p res en t p r ac t i ce .

4) A very s i mil ar comment may be made relativ e

to proc ess economics. The most diff icult task for a

young researcher is to convince himself of the ulti-

mate economies of his new pro ces s vs existing pra c-

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tice. He must be taught to make proc ess economic

studies at least to be able to highlight major differ-

ences in cost. This important aspe ct of an engineeri ng

education requires considerable strengthening in most

metallurgical curricula as they exist today. Courses

taken in other departments simply do not sufficiently

relate; they must be made specific to the metallurgical

industry to be of maximum benefit.

For the Metallurgical Industry

1) Those of us in the metallurgical industry--be it

ferrous or nonferrous--who are more or less respon-

sible for technical innovation in order to stay competi-

tive in world markets can learn much from Union Car-

bide s example. In this case, 15 year s persis tence on

all fronts including technological, marketing, and legal

areas was maintained. The faith and absolute convic-

tion to invest millions of dollars without return for

many years is absolutely necessary for significant in-

novation in a basic industry.

2) It is absolutely neces sar y to have top technical

talent in sever al disciplines in order to develop the

full conviction to persist or to change direction.

3) Discouragements enroute to a major development

will be legion, but they must be viewed for what they

reall y are, and effort cannot be discontinued just be-

cause a specific timetable, written in ignorance of

later-devel oped facts, is violated. We, in business,

tend to live by schedules and timetables. Too rigorou s

application of this discipline in the area of technical

innovation can prematurely terminate potentially prof-

itable inventions.

4) Indu stry needs to understand that there is far

more scientific knowledge available today than has

been brought to bear on the profit problem. To fully

bring it to bear requires a complex harnessing of

many different scientific and engineering disciplines

together with knowledgeable and, to a degree, imagi-

native economic analysis. The pay bachs on technical

innovation in basic indushries are longer in maturing

than generally expected but compensatingly are lar-

ger in magnitude than anticipated. In the present case,

while the lower raw material cost and the lower re-

fractory costs were envisioned from the beginning,

the decreased cost of installed capacity and the sig-

nificant improvements in quality were late develop-

ments and were really not added to the benefits until

the process was well along into its advanced engineer-

ing form.

For the Government

1) We hear a great deal currently about the desira-

bility of breaking industry into small er competing

units. It should be clear f rom the presen t case that

only a corporation with similar res ourc es to Union

Carbide could have proceeded for 15 years without

compensation for its efforts. It should be also clear

that without significant staffs in research, engineering,

marketing, and patent development, a successful con-

clusion would not have been attained. Bigness, per se

is not bad.

2) It should be noted that the success ful co -par tner

in this development was Joslyn Stainless Steel, one of

the smalle st prod uce rs in the United States. While

superficially this might seem to enhance some of the

arguments of the advocates for a larger number of

smaller competitors, size, per se had very little to

do with it. What was significant was the cour age and

vision of the individuals involved and this type individ-

ual, however rare, can be found in any size orga niza-

tion.

3) What was uniquely American about this develop-

ment, and what needs to be preserved and enhanced,

is that one of the largest corporations in the world

sought out and found in one of the smaller corpora-

tions the right partner for this particular development.

This is free choi ce and true nat ural sel ection. No

amount of outside legislated cooperation would have

produced the same result because the natural sel ec-

tion pro ce ss would have been violated. Cooperation

on the scale d emons trat ed he re can only be obtained

from two partn ers freel y convinced of a common goal

that individually benefits each partner to a degree that

justifi es the expense and the risk. That freed om to

search and select the most appropriate partner is one

of the precious heritages of the American free enter-

prise system.

C ONC LUSION

It has been both an honor and a pleasure to recount

the development of the Linde AOD Process and to at-

tempt to generalize from the teachings of this particu-

lar development, concepts which may accelerate other

basic developments in the future. It is particul arly in-

teresting that this Extractive Metallurgy Division Lec-

ture of 1973 bears on a subject of interest to the Iron

and Steel Division. Poss ibly that fact, mor e than all

other s, t estifi es to the relevan tnes s of the AIME where

special interes ts stem from common basic knowledge

and the resulting cross-fertilization of concepts is

one of the great strengths of the Institute.

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