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METALLURGY



OF I ROM




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A TREATISE ON TEE

METALLUEGY OF IKON.



A TREATISE ON THE



METALLUBGY OF IKON



CONTAINING OUTLINES OP



THE HISTOEY OF IEON MANUFACTUEE,

METHODS OF ASSAY AND ANALYSES OF IEON OEES,

PEOCESSES OF MANUFACTUEE OF IEON AND STEEL,



BY H. BAUEKMAN, F.G.S.

ASSOCIATE OF THE ROYAL SCHOOL OF MINES ; ASSOCIATE MEMBEE OF THE
INSTITUTION OF CIVIL ENGINEERS



SIXTH EDITION, REVISED AND ENLARGED

toith immmrxt0 Sit-oo

FROM DRAWINGS BY J. B. JORDAN



OF

UN 1




LONDON

CEOSBY LOCKWOOD AND SON

7, STATIONERS' HALL COURT, LUDGATE HILL

1890
[All rights reserved]




1 Mir wiisse wie me's Else macht
Und wie' s im Sand zu Massie bacht ,
Und wie me's druf in d' Schmidte bringt
Und d' Luppen unter'm Hammer zwingt."

IlEBEL.



GENERAL



PREFACE.



THE importance of the subject has claimed for the
Metallurgy of Iron much careful scientific investi-
gation, both in this country and abroad ; but being
confined, for the most part, to large and expensive
works, or to the pages of scientific periodicals, it is
scarcely available for the technical education of the
great class to whom a general knowledge of the phy-
sical properties of the ores, and the latest and most
approved means of reducing them to a condition suited
for the purposes of the manufacturer, is desirable.

To supply this want is the chief object the author
has had in view in producing this volume, which he
believes will furnish much information that practical
workers of iron, students, and owners of iron mines
require, in a condensed and portable form.

A work of this nature, as a matter of course, must



VI PREFAB.

in a great measure be a compilation from the larger
modern publications on the same subject. The author
acknowledges his obligations to the following published
abroad :

BAER. " Das Eisen," and the Swedish edition by Akerman.

KARSTEN. " Eisenhiittenkunde."

KERL. " Hiittenkunde," vol. iii. 2nd Edition.

KITTINGER. " Erfahmngen."

TUNNER. " Stabeisen und Stahlfabrikation."

"Report on International Exhibition, 1862," in the Leolen

Jahrbuch.

WAGNER'S " Jahresbericht fur technische Chemie."
" Berg und Hiittenmannische Zeitung of Freiberg."
" Oesterreichische Bergwerks Zeitung."
ANSIATTX AND MASSON. " Fabrication du Fer," &c.
DE VATHAIRE. " Etudes sur les Hauts Fourneaux."
GRUNER AND LAN. "Metallurgie du Fer en Angleterre," &c.,

published in the Annales des Mines.
JORDAN. " Metallurgie du Fer au Pays de Siegen," published in

De Kuyper's Revue TJniversette.

He has also perused with considerable advantage,
especially in regard to our Iron Works Percy's
" Metallurgy of Iron and Steel/' Truran's " Iron
Manufacture of Great Britain," load's article " Iron "
in " lire's Dictionary," and articles on Iron Works in
' Engineering."

The illustrations, drawn by Mr. J. B. Jordan, have
mostly been reduced from large-scale drawings, espe-
cially those published by the Technical Institute of
Berlin, under the title " Zeichnungen fiir die Hiitte."

LONDON, March, 1868.



PEEFACE TO THE THIED EDITION.



IN preparing a new edition of this work, to be issued
in the series for which it was originally designed,
advantage has been taken of the opportunity to bring
it up to the present time by the insertion of notices of
the principal facts and processes in connection with
iron making, that have been made public during the
interval of four years that have elapsed since the work
was written. These additions have been introduced in
their proper places in the original text. Among them
will be found notices of the Siemens-Martin steel pro-
cess, probably the greatest advance made in iron-
metallurgy since Bessemer's great invention, as well as
the various plans proposed by Heaton, Ellerhausen,
and others. During the final revision of the sheets,
the Proceedings of the South Staffordshire Meeting of
the Iron and Steel Association were published, contain-
ing many papers which appear to be of great imme-
diate interest, and therefore notices of some of these
have been given as additional notes.



PREFACE.



The present is the third edition, the second having
been issued for circulation in America, with the addi-
tion of a preface and appendix on the Siemens- Martin
process, by an eminent American ironmaster, the
Hon. Abram S. Hewitt, of New Jersey, who is well
known by his elaborate and exhaustive report on the
Metallurgy of iron as exhibited in Paris in 1867.

LONDON, September, 1871.



PEEFACE TO THE SIXTH EDITION.

THE progress in iron and steel manufacture during
the seven years that have elapsed since the last issue
of this volume having been mainly in the direction of
perfecting the appliances and working details of the
great processes introduced between 1858 and 1878,
it has not been found necessary to make any very
great alteration in the principal part of the text ; and
the additions required to bring the information up to
date have therefore been mostly placed as supplemental
notes at the end. These additions are about equivalent
to fifteen pages of the text. The statistical details have
been revised and brought up to the latest dates for
which returns are available.

LONDON, September, 1889.



CONTENTS.



CHAPTER I.

PAGB
INTRODUCTORY AND HISTORICAL SKETCH . .... 1

CHAPTER II.
OUTLINE OF THE CHEMISTRY OF IRON . . . . . . 12

CHAPTER III.
COMPOSITION AND DISTRIBUTION OF IRON ORES .... 53

CHAPTER IV.
ASSAY AND ANALYSIS OF IRON ORES 103

CHAPTER V.
PREPARATION PP IRON ORES 122

CHAPTER VI.
ROASTING OR CALCINATION OF IRON ORES . . . . ,131

CHAPTER VII.
OF THE FLUXES USED IN IRON-SMELTING 145

CHAPTER VIII.
OF THE BLAST FURNACE AND ITS ACCESSORIES .... 160

CHAPTER IX.
CAPACITY AND PRODUCTION OF BLAST FURNACES , , 230



CONTENTS.

< CHAPTER X.

OP THE CONSUMPTION OF FUEL AND DISTRIBUTION OP HEAT IN

THE BLAST FURNACE 258

CHAPTER XI.
VARIETIES AND COMPOSITION OP PIG IRON .... 272

CHAPTEB XII.
METHODS OF MAKING WROUGHT IRON DIRECTLY FROM THE ORE 279

CHAPTER XIII.

REFINING, OR CONVERSION OF GREY INTO WHITE CAST IRON . 289

CHAPTER XIV.
PRODUCTION OF WROUGHT IRON IN OPEN FIRES ... 303

CHAPTER XV.
REVERBERATORY FINERY OR PUDDLING PROCESS . .315

CHAPTER XVI.
FORGE AND MILL MACHINERY . .' . . * . 349

CHAPTER XVII.

/- BEHEATING AND WELDING 373

CHAPTER XVUI.
V METHODS OP PRODUCING STEEL . ., . . . .401

CHAPTER XIX.

ANALYSIS OP CAST AND WROUGHT IRON AND STEEL . . .480
CHAPTER XX.

MECHANICAL PROPERTIES AND TESTS OF MALLEABLE IRON AND

STEEL 496



SUPPLEMENTARY NOTES 608

INDEX 519



LIST OF ILLUSTRATIONS.



1. Gjers' calcining kiln.

2. Swedish gas calcining kiln.

3. Styrian kiln for pyritic ores.

*. Charcoal blast furnace at Safvenas, vertical

5. Plan of charcoal blast furnace.

6. Vertical section of cupola blast furnace. Barrov-in-Furuess

7. Front view of hearth and dam of blast furnace.

8. Staffordshire blast furnace, section across hearth

9. Double-acting blowing engine, vertical section.

10. Hot blast stove, with U pipes. Dowlais.

11. Hot blast stove, with pistol pipes. Oberhausen.

12. Wasseralfingen stove at Neustadt.

13. Cowper's hot blast stove, vertical section.

14. Plan of a pair of Cowper's stoves.

15. Arrangement of bricks in Cowper's stove.

15* Whitwell's stove, as applied to a blast furnace at Consett.

16. Water twyer and blow pipe for hot blast. Bhonitz.

17. Furnace top, with cup-and-cone charger. South Wales.

18. Furnace top, with La ngen' s charger. Esehweiler.
18. Biittgenbach's blast furnace.

19. Rachette's blast furnace, vertical section

20. Eachette's blast furnace, plan through twyers.

21. Comparative sections of modern blast furnaces

22. Catalan finery fire.

23. Vertical section of refinery.

24. Plan of refinery.

25. Puddling furnace.

26. Carinthian gas puddling furnace.

27. Eastwood's mechanical puddler.

27#, 27b, 27c. Danks's rotatory puddling furnace.

28. 70-cwt. shingling helve.



Xii LIST OF ILLJSTRATIOTSk,

FIG.

29. Thwaites and Carbutt's steam hammer.

30. Ramsbottom's duplex steam hammer.

31. Double lever squeezer. Dowlais.

32. Boiling mill.

33. Bail mill roughing rolls.

34. Rail mill finishing rolls.

35. Universal rolling mill.

36. Cropping shears. Dowlais.

37. Reheating furnace.

38. Sections of piles for finished iron.

39. Siemens' gas furnace, vertical section.

40. Siemens' furnace, plan of flues.
400, Ponsard's gas furnace.

40>. Ponsard's recuperator, transverse sectioa.
40c. Ponsard's recuperator, longitudinal section.

41. Steel converting furnace.

42. Steel melting furnace.

43. Siemens' steel melting furnace, vertical section.

44. Siemens' steel melting furnace, plan of flues.

45. Bessemer' s steel converting apparatus, detailed section.

46. Bessemer's apparatus, general view, with casting apparatus
46<z. Walker's 10-ton converter, side elevation.

46*. Walker's 10-ton converter, transverse section.

47. Siemens-Martin steel melting furnace.

48. Pernot's steel melting furnace, longitudinal section.

49. Pernot's steel melting furnace, transverse section.




METALLURGY OF IKON



CHAPTER I.

INTRODUCTORY AND HISTORICAL SKETCH.

THE subject of iron- smelting is the largest and most
important in the whole domain of metallurgy, and, at
first sight, presents a remarkable contrast to all other
branches of the smelter's art. For in the case of most
of the other metals employed as such in the arts, we
have, as sources of supply, a numerous class of minerals
varying greatly in richness and composition, and sus-
ceptible of reduction to the metallic state by processes
also differing greatly among each other ; while, in the
case of iron, the few minerals that can be made useful
as ores are restricted within much narrower workable
limits, and form only one class of chemical compounds,
namely, oxides, whose reduction can be effected practi-
cally only by one agent that is, carbon or carbonic oxide.
But as a very high temperature is necessary to effect
the reduction, the metal almost always combines with a
greater or less proportion of the reducing agent, as well
as of other elementary substances, such as silicon,
sulphur, and phosphorus, thfat may be present either in
the ore, the fuel, or the flux, so that the ultimate
result is never a pure metal, but a series of compounds,



2 METALLURGY OF IRON.

varying in properties from great hardness to perfect
malleability, and from ready fusibility to almost abso-
lute infusibility.

Practically speaking, absolutely pure iron may be
said to be of no commercial value. But, on the
other hand, extraordinarily small traces of foreign
elements exert a very marked influence on the metal,
and it is precisely these small and, in many cases, un-
noticed differences of composition, that render so many
points in the chemistry and practical working of iron
obscure and difficult to be understood. When it is
considered that the investigation of such problems calls
for researches involving the utmost refinements of
analytical chemistry, it is not remarkable that contra-
dictory statements and opinions still abound on many
points of the chemistry of iron-making.

The mechanical considerations involved in this sub-
ject are almost as important as the chemical; for,
unlike the smelter of other metals, who is able by fusion
alone to bring his finished product to a merchantable
state, the iron smelter has to deal with pasty infusible
masses, which require to be compacted and moulded by
pressure by powerful machines, such as hammers,
presses, rollers, &c., before they can be made available
for consumption.

In view, therefore, of the great magnitude of the
subject, it may be as well to state, at starting, that the
treatise now placed in the reader's hands is devised to
furnish such information connected with the metallurgy
of iron as may be necessary for the elucidation of the
general principles upon which the processes used in the
reduction of iron from its ores are based. While, there-
fore, referring the student for the detailed discussion of



INTRODUCTORY AND HISTORICAL SKETCH. d

the various points to the larger works on the same sub-
ject, such, for example, as the elaborate volume pub-
lished by Percy, in this country, and those of Karsten.
Flachat, Yalerius, Julien, Tunner, and others on the
Continent, we shall proceed to notice in as succinct
a manner as possible, the principal facts and opinions
current in the modern practice of iron- smelting under
the following general headings : -

1. Outline of the chemistry of iron from the metallur-
gical point of view, noticing only such compounds as
immediately interest the smelter.

2. Composition modes of occurrence and distribution
of the ores of iron.

3. Methods of assaying, mixing, and fluxing ores.

4. Description of processes whereby the ores are
reduced to the metallic state.

Before entering upon the consideration of the above
subjects, it will be convenient to state broadly the
nature of the finished products of the iron smelter's
labour, and to glance rapidly at the historical part of
the subject.

Of the Products of Iron Smelting Cast Iron Malleable
Iron Steel.

Iron is employed in the arts under three several
states, whose variable properties are mainly due to dif-
ferences in the quantity of carbon present, and in a
lesser degree to that of other foreign matters. When
alloyed with a maximum of the latter element, an
amount which in ordinary smelting does not exceed
6 per cent., or fall below 2 per cent., the substance
obtained is known as cast iron or pig metal This

B2



4 METALLURGY OP IRON.

is a hard and comparatively brittle substance, which
can be readily fused at a high temperature, and is
susceptible of being moulded into solid forms by cast-
ing, but also in most modern iron works forms an
intermediate product in the manufacture of the other
classes. According as the metal may be most adapted
for founders' or forge-masters' use, it is distinguished
as forge or foundry pig.

Wrought or Malleable Iron. This, the nearest approach
to the chemically pure metal that can be obtained on
the large scale, may be almost absolutely free from
carbon, and never contains more than 0*25 per cent.
It is a soft, malleable, and extremely tenacious sub-
stance, infusible, except at the extreme temperatures
obtainable in furnaces of special construction, but
capable of being agglomerated by pressure, when at a
white heat, to a compact state by the process of welding.
When heated and suddenly cooled, it retains its soft*
ness. It may be produced either directly from the ore
or by the conversion of pig iron. The varieties of
malleable iron are distinguished by many different
names, but these have reference rather to form and
destination than to differences of composition.

Steel. Those varieties of iron in which the amount of
carbon is above the maximum of malleable, and below
the minimum of cast metal, are known as steel. The
distinguishing property of this class of products is the
power of being hardened or softened at pleasure, by
sudden or rapid cooling, by the process known as tem-
pering. Being intermediate in position between wrought
and cast iron, steel is both fusible and malleable, but
requires a higher temperature for fusion than the latter,
and greater compressing power, owin^ to its lower



INTRODUCTORY AND HISTORICAL SKETCH. 5

welding temperature, than the former. Those varieties
that are richest in carbon are the hardest and most fusible,
and are known as strong steels, while those that are
nearer malleable iron in composition are distinguished
as mild steek or steely irons. Steel may be obtained
either direct from the ore at one operation, or indirectly
by a variety of processes of greater or less complexity
from either cast or wrought iron.

Outline of the Progress of Iron Manufacture. The
history of the production of iron is probably almost
co-extensive with that of the human race ; at least, it goes
back far beyond the periods of authentic history.
According to the Pentateuch (Gen. iv. 22) the dis-
covery of iron is attributed to Tubal Cain, who is said
to have been sixth in descent from Adam. Pagan
tradition assigns the discovery to Vulcan, placing it
about the time of Deucalion's deluge. / There can be
little doubt that the discovery was made at a very
early period, as the production of small masses of
malleable iron is one of the simplest of all metallur-
gical operations, requiring only a small furnace without
blowing apparatus, such as can be made by digging
a hole in the side of any bank exposed to the prevailing
wind, a supply of easily reducible ore, ancl charcoal for
fuel. Such processes) as these have been described as
in use in Africa by Mungo Park, and are still employed
in Birmah ; and probably something of the same kind
is indicated by the tradition which ascribes the discovery
of iron in Scythia to the effects of forest fires in dis-
tricts containing iron ores, when portions of the reduced
metal are said to have been found among the ashes of
the burnt trees.

It may have been, however, that the masses of iron



O METALLURGY OF IRON.

referred to were meteorites, whose existence was first
made apparent by the clearing of the ground.

Homer refers several times to iron and steel. Thus
in the twenty-third Iliad, Achilles, at the funeral games
of Patroclus, gives a disc of iron as the prize ; and
in the ninth Odyssey, the hissing of the burning stake
that Ulysses plunges into the eye of Polyphemus is
compared to the noise produced when steel is hardened
by quenching it with water when at a red heat.

Probably the first important improvement in the
manufacture was the introduction of the artificial blast,
which is of great antiquity. In Egyptian sculptures
of the reign of Thothmes III. (1505 B.C.) smiths are repre-
sented working at a forge, which is provided with two
simple leather bellows, worked by the pressure of men's
feet for the exhaust, and inflated by strings pulled by
hand, in a manner exactly similar to that still employed
in Birmah.

Aristotle (B.C. 384-322) describes the process of making
cast steel used in India, which is still produced under
the name of wootz ; and also the manner in which the
Chalybes of the Euxine procured iron. Pliny (A.D. 23-
79) mentions the great masses of iron ore still worked
in Elba, Styria, and Spain, and describes the methods
of making iron and steel, especially remarking that the
quality of the latter depended upon the water used in
quenching, and that small tools were tempered in oil.
(" Natural History/' bk. xxxiv. chap. 41.)

Diodorus (B.C. 60-40), in describing the iron works of
Elba, states the ore was reduced to small pieces and
heated in furnaces ; the charge, when properly softened,
was removed and divided into small masses, which had a
spongy appearance (blooms), and were exported to the
main land of Italy for conversion into tools.



INTRODUCTORY AND HISTORICAL SKETCH. i

Galen (A.D. 131) remarks that knives made of Indian
iron (steel) were remarkable for their strength and
hardness, but were often so brittle that the cutting
edge splintered off, owing to their having been ira
properly tempered.

/According to Franquoy, bellows with valves were in-
troduced by the Romans into Gaul during the fourth
century A.D. These, although single acting and made
of leather, were a considerable advance upon the savage
form, which required strings for their inflation. The
wooden double bellows, which are still in use in some
parts of the Continent, may be regarded as the pre^
cursors of the cylinder blowing engine, and were intrc=
duced into the Harz about 1620, either from Franconia
or Thuringia.

During the middle ages the great improvement
consisted in the gradually increasing height of the
furnace, consequent on the use of ores of an infusible
and difficultly reducible character. This necessitated
a special means of withdrawing the reduced mass
of iron (lump or bloom), which was effected through a
lateral opening in the hearth, or lower part of the