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NON-TECHNICAL CHATS ON IRON AND STEEL
AND THEIR APPLICATION TO MODERN INDUSTRY

BY

La VERNE W. SPRING, A.B.

CHIEF CHEMIST AND METALLURGIST, CRANE CO., CHICAGO

WITH TWO HUNDRED AND NINETY-FOUR ILLUSTRATIONS AND DIAGRAMS

NEW YORK

FREDERICK A. STOKES COMPANY

PUBLISHERS

Copyright, 1917, by

Frederick A. Stokes Company

All rights reserved, including that of translation

into foreign languages

TO

MY FELLOW WORKERS

IN THE VAST IRON AND STEEL INDUSTRY

THIS BOOK IS

AFFECTIONATELY DEDICATED

FOREWORD

It has long been a desire of the author to put into non-technical form the interesting data here given. During several years spent in the service of one of the great steel companies of this country, first in the laboratories and afterward in the rolling mills, he acquired a love for the industry that is now of fairly long standing. Spending as much of his spare time then and since in visiting various parts of that mammoth plant and as many others as he was able, he has always felt that this extremely interesting subject could not fail to prove fascinating even to those who had previously known little of the manufacture of steel and steel products. Later work with gray and malleable cast irons and with cast steel enlarged the outlook and further urged his sharing these interesting things with others not so fortunately situated.

Such an inspiration, if it may so be called, is the reason for the appearance of these articles. Practically as here reprinted, the first thirteen of them were published during 1915 and 1916 in serial form in the “Valve World,” the house organ of Crane Company of Chicago, with which the writer for some time has been connected. The enthusiasm with which they were received has been very gratifying, while the scores of letters bearing favorable comment testify to the correctness of the judgment that the metallurgy of our most useful metal, iron, is of very general interest.

It may be remarked by some that certain of the statements made in the book are not strictly accurate in that few details have been stated or exceptions made. This is true, but it seemed necessary if main facts were to be made to stand forth with the boldness required to accomplish the purpose which the author had in mind. The chapters are in no way intended to be an encyclopedia of the subject. The idea throughout has been to present only the main points and to show the derivation of the products from the raw materials and their relationships to each other. In other words the book is intended only as a sort of outline. References are given which will aid in the selection of works to be consulted by any who are sufficiently interested to go farther.

Without the encouragement and coöperation of Crane Company and the kind assistance of friends, some within and some without the iron and steel industry, this little book would not have been possible. Special mention must be made of the aid given by Messrs. I. M. Bregowsky, J. A. Matthews, C. D. Carpenter, and others whose reading of and suggestions concerning parts of the manuscript were of much help. Thanks are due also to many individuals and firms for their very hearty coöperation in furnishing information and the photographs which appear in the pages of the book.

L. W. S.

Illustrations are from the following sources:

A. M. Byers Co., Pittsburg.—National Tube Co., Pittsburg.—U. S. Steel Corporation, New York.—Tennessee Coal, Iron & Railroad Co., Birmingham, Ala.—Shenango Furnace Co., Pittsburg.—Pickands, Mather & Co., Pittsburg.—United States Geological Survey.—Wellman-Seaver-Morgan Co., Cleveland, O.—Lackawanna Steel Co., Buffalo.—Cleveland-Cliffs Iron Co., Ishpeming, Mich.—J. H. Hillman & Sons Co., Pittsburg.—Harbison-Walker Refractories Co., Pittsburg.—By-Products Coke Corporation, Chicago.—H. Koppers Co., Pittsburg.—Federal Furnace Co., Chicago.—Crucible Steel Company of America, Pittsburg.—Crane Co., Chicago.—Interstate Iron & Steel Co., Chicago.—LaBelle Iron Works, Steubenville, O.—Morgan Construction Company, Worcester, Mass.—J. A. Matthews. Syracuse, N. Y.—McLain’s System, Milwaukee, Wis.—Allis-Chalmers Co., Milwaukee, Wis.—J. H. Williams & Co., New York.—Griffin Wheel Co., Chicago.—U. S. Molding Machine Co., Cleveland.—Bradley Manufacturing Co., Bradley, Ill. (Sears, Roebuck & Co., Chicago).—Snyder Electric Furnace Co., Chicago.—Commonwealth Steel Co., St. Louis.—John A. Crowley & Co., Detroit.—Illinois Steel Co., Chicago.—Pickands, Brown & Co., Chicago.—“Sketches of Creation,” by Alexander Winchell. Harper & Bros., New York.—“Descriptive Metallurgy of Iron,” by S. Groves.—“Materials of Engineering,” by R. H. Thurston. John Wiley & Sons, New York.—“Chambers’ Encyclopedia.” J. B. Lippincott, Philadelphia.—“Cast Iron in the Light of Recent Research,” by W. H. Hatfield. Charles Griffin & Co., Ltd., London.—“Handbook of Chemical Technology,” Wagner-Crookes. D. Appleton & Co., New York.—“The Ore Deposits of the United States and Canada,” by J. F. Kemp. McGraw-Hill Book Co., New York.—“The Valve World.” Crane Co., Chicago.—“The Romance of Steel,” by H. Casson. A. S. Barnes & Co., New York.—“The Metallurgy of Steel,” by Harbord & Hall. Chas. Griffin & Co., Ltd., London.—“Metallurgy of Steel,” by H. M. Howe. McGraw-Hill Book Co., New York.—Tomlinson’s “Encyclopedia of Useful Arts” (1854). G. Virtue & Co., New York.—“Liquid Steel,” by E. G. Carnegie. Longmans, Green & Co., New York.—“Iron and Steel in All Ages,” by James Swank. American Iron & Steel Association, Philadelphia.—“The A.B.C. of Iron and Steel.” Penton Publishing Co., Cleveland, O.—“The Iron Age.” David Williams, New York.—“The Iron Trade Review.” Penton Publishing Co., Cleveland, O.—“High Speed Steel,” by O. Becker. McGraw-Hill Book Co., New York.

CONTENTS

NON-TECHNICAL CHATS ON IRON AND STEEL

CHAPTER I
THE EARLY HISTORY OF IRON

Prehistoric Man

When in imagination we see the iron maker of early days sitting cross-legged on his platform between two crude bellows formed from goat skins with slits for air intakes and nozzles of bamboo, working them alternately to deliver their pitifully small streams of air into the hole in the side of a bank of clay which served as a furnace, we wonder at his patience; and after long hours of such effort his reward was only a few pounds of iron!

Contrast with this, if you please, the modern blast furnace with its towering height of 100 feet, its four huge heating stoves, the big blowing engines which each minute deliver to the furnace 50,000 cubic feet of blast, and the whole array of dust arresters, gas washers, and automatic ore and coke handling machinery which are essentials of this king of modern metallurgical devices. How insignificant seems the output of the ancient furnace when compared with the daily yield of 500 tons from this giant of to-day!

How has this come about?

The First Razor

Looking back over the centuries we see a period many thousands of years ago when primitive man lived in caves or other rude habitations and was entirely without the implements which we now consider indispensable. The weapons with which he defended his wife and babes from the wild beasts and from his warlike neighbors were clubs, wooden spears with perhaps a bone or shell tip, and hatchets of chipped stone tied with thongs of hide into a split stick. He managed by ingenious snares and his crude weapons to provide game and fish for the support of his family.

He did not shave often, for his wife was not as particular in regard to his appearance as are modern women, but when such a thing happened, a piece of shell was his razor. The good wife had no steel needles with which to sew together skins for their crude clothing. If she darned her husband’s socks it is not recorded, nor did she use steel crochet hooks in making the “doilies” for their parlor table.

When grain began to supplement the wild game, fruit, and berry diet, it was broken between flat stones or ground in stone mortars. Fires were kindled after long and laborious twirling or rubbing together of two dry pieces of wood. With his stone hatchets and by liberal burning away of parts by fire he formed his canoes from trunks of fallen trees.

This was the “Stone Age,” and iron and steel were unknown and not to be heard of for many thousands of years.

In various parts of the world copper always has occurred “native”; i.e., in the metallic form and not in combination with other elements as an earth or ore. As the centuries rolled on, man eventually learned that this soft red metal could be pounded into thin-edged implements and that it made more useful tools than those of stone, which his ancestors had taught him to form. Some of these metal implements were hard and had fairly good cutting edges, made so by accidental or intentional presence of tin, and little did he dream that the twentieth century upon finding his buried bronze implements would think his crude alloy so wonderful and talk reverently of a “lost art of tempering copper.”

Implements of the Stone Age

Gold, too, became known to him because it also occurs “native.” Its melting point was low enough that he could fashion it into ornaments, idols, and other articles for religious purposes. But during the hundreds of centuries of the “Stone Age” and during much of this—the “Bronze Age”—copper, bronze, and gold were the only metals used. Though the smiths became very dextrous in casting and modeling these metals, they yet knew not iron or steel.

Implements of the Bronze Age

Round about them during these many centuries, as multi-colored earths or rocks, were the ores of various metals. They little dreamed that when rightly treated certain of the heavy red, yellow, or black earths which lay right at their doors could give up that most useful metal, iron. No one even had knowledge of such a substance, for, unlike copper and gold, iron never occurs “free,” having too great a tendency to chemically combine with other elements, for example, oxygen of the air, with which, in moist climates, it so readily forms “iron rust.” Besides, its melting point is high and so much heat and carbon are needed for its “reduction” from the ore that, during the thousands of years that had gone before, it had never been produced.

Primitive Furnace for Smelting Iron

But one day by accident and under fortunate coincidence of rich ore, high heat, and plenty of carbon in the form of charcoal from the wood, a lump of metallic iron was formed underneath a pile of logs which had got afire and burned fiercely because of a high wind. When pounded between two stones this new heavy metal, too, was malleable and could be formed into a spearhead superior to anything yet known. Every one was interested and an observant one soon “doped out” that certain earths could be made to yield this new metal, iron.

The art of extracting it spread slowly, each artisan learning from his neighbor, and, as rich ores were plentiful in many districts, iron became more and more generally produced. Not only in one country was this so but evidence shows that in many others—in Egypt, Chaldea, Borneo, India, China, etc.,—roughly similar processes and crude furnaces came to be used.

Tubal-Cain, supposedly about 4000 years B.C., is mentioned in the Bible as an “artificer in iron and brass,” and a wedge of wrought iron was buried in the great pyramid of Cheops probably as early as 3500 B.C. This wedge was recently found and is now the property of the British Museum. The Chinese made use of iron many centuries before the Christian era, but the Assyrians are supposed to have been the first to use the metal on a really extensive scale.

The Pillar at Delhi, India

The much discussed pillar at Delhi, India, which is still standing in a remarkable state of preservation, is twenty-two feet high. It is made up of several wrought iron sections cleverly welded together. As the natives regard it with religious awe, metallurgists have been unable to make thorough investigation and chemical analysis. While the date of its erection is somewhat in doubt, it is supposed to have been about the 4th or 5th century A.D.

But from our modern viewpoint those early iron furnaces were queer things. The first were little more than piles of ore and wood or charcoal on the tops of hills where a brisk wind would make a hot fire. Later, with the invention of the crudest of bellows, the smelting was done in small holes in the side of banks of clay, charcoal made from the forest trees being used as fuel. Indeed, some of these types of furnaces still exist and are so operated to-day in neglected districts in Western India and elsewhere, producing their little five to 100 pound balls of iron after several hours of tedious work.

When the Romans invaded Britain (now England), they found the Britons making iron in crude furnaces called bloomaries; and not a great deal of improvement, except in size, was made up to Queen Elizabeth’s time, when strict laws had to be enacted to prevent destruction of the forests which were being denuded for production of charcoal, coke, which we know so well, not yet having been produced for fuel.

Milady’s Needle

The Catalan Forge

But the real forerunner of our modern blast furnace was the Catalan forge, developed in and named from Catalonia, north Spain, where it originated. The Catalan, however, and all of such crude early furnaces, including those thus far described, produced a variable kind of what we now know as “wrought iron,” and our modern “cast” iron did not appear until about 1350 when, with larger furnaces, an excess of charcoal, with greater heat and other favorable conditions, the Germans found that the pasty, difficultly melting metal could be made to absorb carbon enough to make it easily fusible. This was the secret.

To state the matter in a simple way, iron ore, which is essentially a natural “iron rust,” is the metal, iron, held in the strong chemical grip of the gas, oxygen, which normally forms one-fifth of the air we breathe. As you note, the combination forms a substance entirely unlike either the iron or the oxygen, but both of these can be regenerated from it (the ore) by chemical methods. Under influence of high heat (this is one of the chemical methods, by the way), this stranglehold can be broken by carbon, of which lampblack, graphite, charcoal, and coke, are our most familiar examples. The result, in the small, crude, and inefficient furnaces of long ago was a disappointingly small ball of crude iron, pasty and scarcely meltable, even at highest heats, but soft and malleable when cold. As mentioned, it was a variety of what is now commonly called “wrought iron.”

A Catalan Forge With Italian Trompe, or Water Blower

The ancients got this far.

But this was not “cast iron.” When, however, much more charcoal was present in the highly heated furnace than was necessary simply to combine with the oxygen of the ore, the liberated iron greedily absorbed enough of the extra carbon to change its own nature. The metal then became very fluid, whereas before it had been pasty and stiff even at much higher temperatures, or, indeed, at white heat. This liquid iron could be “cast,” that is, poured into molds and in that way made into various useful shapes. It therefore became known as “cast iron” because of this property.

So the brittle metal (cast iron) in our kitchen ranges, for instance, is only the early malleable form of the metal surcharged with or having a large amount of carbon (3½ per cent to 5 per cent) in its make-up, and it is this supercarbon content which confers the fluid quality while hot and the extreme brittleness when cold. True, there are other important constituents in our modern cast iron, but for our present purpose they need not be dealt with.

It has been stated that the ancients got only as far as balls of wrought iron. They really got further as their very fine sword steels show—the “Wootz” of India, the “Damascus” of Syria, and later the “Toledo” of Spain. These they produced by heating rich ore in very small, closed crucibles with just enough carbon (pieces of wood or green leaves) to make what we now call “carbon tool steel.” As carbon steel is simply iron which has absorbed not over 2 per cent of carbon (cast iron described above has a supersaturation with its 3½ per cent to 5 per cent of carbon and therefore is entirely different) they were able to make it in small quantities. When hardened by cooling quickly in water, a forged-out blade of this product would cleave without dulling its edge a piece of iron, it is said, or cut cleanly a tuft of silk floss tossed into the air. These steels attained well deserved renown.

While no one can desire to cast the slightest disparagement on the product of that period, much of which was excellent, astonishingly so considering the period, a moment’s consideration will convince one that modern products not only do not suffer in comparison but in reality are immensely superior. The ancients had little or no knowledge of the reason for the proper qualities of their tools and they made the metal from variable materials in a crude way in such small quantities that little uniformity was possible. While some of the product was undoubtedly excellent, much must have been less desirable.

Modern discoveries and inventions, with the great mechanical progress of the last three centuries and the scarcely half-century-old application of chemical control, have given during recent years products of great uniformity and marvelous quality. What can compare with thirty thousand pound lots of steel turned out from one Bessemer converter each seventeen minutes during the 24 hours in the day, that is, a total of 1300 tons or 2,600,000 pounds, in which not only the main controlling element, carbon, but also four lesser ones, silicon, manganese, sulphur, and phosphorus, are held within extremely narrow limits; or the modern blast furnace which produces a million pounds each 24 hours, run with the same certainty of control? Modern high-speed steels which are every day being made have such high quality that tools formed from them will stand up for hours working red-hot under a lathe speed of two or three hundred linear feet per minute taking a deep cut and “plowing out” chips faster than a laborer can carry them away.

The German Stuckofen

Modern war armament which has recently been so well advertised is sufficient answer as to whether modern metallurgy is in advance of that of centuries ago.

The only necessity for such comparisons is that it seems to be a failing of many to think that our forefathers were more wise and better in other ways than we. It was but a few years ago that the fallacious announcement was made that during archeological excavations in Egypt there had been found a fully equipped telephone system. The inference intended to be conveyed, of course, was that Bell’s invention of the telephone had been antedated many hundreds of years.

A German Blast Furnace of Fifty Years Ago

The forerunner of the modern steels was crucible steel, first made by Huntsman about the middle of the eighteenth century. Previous to his time steel had been made by the “cementation” process by which method hammered-out bars of wrought iron were given a hard steel crust by heating to a red heat in charcoal or bone dust. Huntsman’s product began to come so uniform and of such quality that his competitors were quite outdistanced. It is related that one of them took advantage of a very severe storm to gain admittance to the forest forge of Huntsman, who, he knew, could not refuse shelter at such a time. What he beheld was a very simple thing—the melting in a clay pot of pieces of cementation steel.

Even to-day the crucible process is holding its own where quality is the main consideration. It is the method by which practically all of the tool, automobile, and other special steels of to-day are manufactured and can hardly be given too high a rating. The newly devised electric furnace process is the only possible competitor in sight. Of course for quantity and for lower cost the Bessemer and the open-hearth processes are the only available ones, but crucible steel has been the mighty factor in the commercial development of the world—at least until the latter half of the last century when the two other processes last mentioned began to acquire honor of their own without, however, detracting much from the importance of crucible steel as the steel of “quality.”

The First Iron Casting Made in America

Though more interesting than any of the “six best sellers” much of the subsequent history of iron will have to be passed over at this time. We can now only mention those very great and revolutionary discoveries and inventions which led to and absolutely are the basis of the quantity and excellence of modern irons and steels; namely, the trial for a time of coke made from pit coal by Dud Dudley of England and its failure which was turned into a great success a century later (about 1713) by Abraham Darby; Watt’s invention of the steam engine in 1770 which made possible application of a strong continuous blast; invention of the process of “puddling” of iron and of the rolling mill by Cort about 1784; the introduction by Neilson about 1830 of the hot instead of the cold blast which increased blast furnace production fourfold; the regenerative system of furnace heating invented by Frederick and William Siemens; and the invention of the Bessemer and Siemens-Martin or open-hearth processes which provided methods for steel making on such an immense scale that this invaluable material was made available for general purposes.

It should be repeated that the inventions just mentioned have been of the utmost importance to the iron industry, and through them only has it acquired its consequence of to-day. Without them we would not have the wonderful steel bridges, the skyscrapers, the gigantic steel ships, the all-steel railway trains, etc., and the hundreds of iron products that are to-day so plentiful and so constantly about us that we disregard their presence. It is difficult thus to pass them by, but as most of them will be referred to in later chapters we must do so.

Early iron making in America is of interest to us and must be briefly stated.

The colonists were aware of some of the iron ore deposits about them and sent samples to England where these yielded very fine iron. In 1619 a company known as the “London Colony” was sent out from England to engage in the manufacture of iron at Falling Creek, near Jamestown, Virginia, but three years later all were massacred by Indians. It was many years before attempt was again made to manufacture iron in Virginia.

About 1637 the General Court of Massachusetts granted to Abraham Shaw one-half of the benefit of “any coles or yron stone w^ch shall bee found in any comon ground w^ch is in the countryes disposing.” Apparently little resulted from this high-sounding grant.

Real iron making in America began six years later with John Winthrop, Jr., and his “Company of Undertakers for the Iron Works” which for many years operated in several localities in the New England States. Heaps of cinders left from their furnaces may still be seen and testify to their very extensive operation. One of Winthrop’s men was Joseph Jenks, who became known as the “Tubal-Cain” of New England. What is claimed to have been the first casting made on the Western Continent was made by him. It is a small pot, which was acquired and is said to be still owned by the family of Thomas Hudson, a descendant of Hendryk Hudson.

Sand molding as used at present was introduced by an ingenious Englishman, Jeremy Floris, and is vastly superior to the previously used system of molding in clay. Hollowware began to be extensively produced about this time.

As the country developed, iron works sprung up here and there and various kinds of articles came to be regularly manufactured. Of the early plants we can only mention the Stirling Iron Works, at Warwick, New York, which made the great 186–ton chain with links weighing 140 pounds each, which spanned the Hudson River near West Point, and where in 1816 was cast the first cannon made in America; the foundry of Sharp & Curtenius, in New York, where was cast the first steam cylinder; and the Trenton Rolling Mills, which first rolled iron as fireproof structural material.

Before the Revolutionary War the colonies exported considerable bar and pig iron to Europe, and as early as 1791 England began to foresee that this country would eventually be a serious rival.

Pittsburg’s great advantage as an iron and steel center has been due to its proximity to an extensive seam of bituminous coal and ore in adjacent counties, and to its location so near the Great Lakes, which provided cheap water transportation for the Lake Superior ores. The first iron works there was that of Turnbull & Company, which was established in 1790.

Though Reameur, a Frenchman, is the accredited discoverer of the process of malleableizing cast iron, Seth Boyden, in a little shop in Newark, New Jersey, made malleable iron castings a commercial success.

Two Modern Blast Furnaces, Showing Skip-Hoists, Cast Houses, Stoves, and Ore Pile

The utilization of the great beds of high grade coking coal of eastern Pennsylvania, well known as the Connellsville district, and the discovery and development of the Lake Superior ore deposits have made the United States the leading producer of iron and steel of the world. The development of the Birmingham, Alabama, district, also has been a chapter of great importance but lack of space forbids description at this time.

We can have only a very slight appreciation of the debt which civilization owes to iron, for practically everything we see or with which we daily come in contact contains or has resulted from application of iron in some way or other. Our cooking utensils and implements (even the enameled and tinned ones), the kitchen range, the water and drain pipes, and the furnace and heating plants of our houses, are they not largely of iron? Our main building materials—the steel frames of skyscrapers and bridges, and are not even wood, brick, stone, and cement either shaped, molded, or of necessity made by aid of iron machinery? The conveyances by which we travel—wagons, automobiles, street cars, steam railways and steamships—how would they be possible without iron or steel? Consider the power plants of our factories, of gas and electric lighting plants, the pumping machinery and distribution systems of water works, mines, etc. Would the electric current which supplies so much of our power and light be known to-day or even be possible but for the magnetic properties of iron? And how many of the materials and articles which we wear, use, and have about us constantly would be in any way possible without the wealth of steel machinery and tools which are available and absolutely necessary for their production?

The iron industry is often spoken of as the barometer of a people’s civilization. If all iron and iron products and their influence upon the world should be obliterated, it seems impossible that we could be even started on the road to civilization.

No matter how we try, probably none of us ever realizes the immensity and importance of the iron and steel industry with approximately 460 huge blast furnaces here, 5000 cast and malleable iron foundries, about 1000 Bessemer and open-hearth steel and some 3000 puddling furnaces, and the many thousands of factories which each day are turning the products of these into rails, plate, wire, pipe, and the infinitude of finished articles which enter into and are mighty factors of our civilization. Yet with these furnaces, forges and factories at our very doors, 99.9 per cent of us are entirely oblivious to their wonders and to their presence except to be annoyed by their noise and smoke. Even the blacksmiths and their service we scarcely note, though they are daily fashioning for us a material which is vastly more important and more wonderful than any of the “Seven Wonders of the World.”

CHAPTER II
THE RAW MATERIALS

A story has it that a minister once visited a friend who was a zoölogist. Upon realizing for the first time how highly organized a creature was the humble earth-worm with its three-layer skin covering, alimentary canal, nephridia or excretory system, reproductory organs, rude nervous system, and setæ for purposes of locomotion, he exclaimed: “Wonderful! I had always supposed that worms were only skin and squash.”

With millions of tons of heavy reddish-brown earth from northern Michigan and Minnesota going by our doors continuously during the shipping season, the position of most of us is very similar to that of the minister relative to the earth-worm. We know that something is going on but we are not aware of its importance or the immensity of it.

Iron Ore

Almost every one knows that there are extensive copper deposits along the Lake Superior shore of what is now northern Michigan. In the 17th century word of these was several times taken to Europe where in old publications was mentioned a huge ingot of copper from which the Indians chopped pieces with their hatchets. At that early date maps of the region were drawn which are wonderfully accurate, and, from time to time over a period of a century and a half, adventurers attempted to gain wealth in this favored region.

Map Showing Distribution of Iron Ores of America

However, despite the definite knowledge of considerable mineral wealth there and rumored claims of much more, Michigan at the time of her admission to the Union in 1836 bitterly opposed having what is now the northern peninsula included within her territory in lieu of a ten mile wide strip of northern Indiana and Ohio, and it has been said that she nearly went to war to resist it. Even after the discovery of the iron ore deposits, no one realized the full importance of the minerals of this region.

Showing Typical Mesaba Ore Bed Which, after Earth Covering is Removed, Becomes an Open Pit Mine

During the many years of campaigning for Federal help in the building of a canal at Sault Sainte Marie, the fisheries, valued at $1,000,000 a year, were given as the leading reason why a canal should be built, and it was no less a personage than Henry Clay, who, in opposing appropriation for this purpose, referred to the project and the district as “beyond the remotest settlement, if not in the moon.”

Now, within eighty years of that time, the annual tonnage of shipping passing through the Sault Sainte Marie canal is as great as the combined tonnage from the ports of New York, London, Liverpool, Antwerp, and Hamburg, and, as against the $1,000,000 value of the fisheries, the value at the mines of the ore alone shipped from this region amounts to about $100,000,000 yearly.

Shenango Open Pit Mine, Chisholm, Minn.

Interior of a Hard or Lump Ore Mine

As the copper deposits are mostly along the shore of the lake and the great iron ore beds occur seven or more miles inland, the latter were not discovered until Sept. 19, 1844, when William A. Burt, a Deputy United States Surveyor, noticed that the needle of a solar compass of which he was the inventor became unreliable. In looking about to discover the magnetic source which must be the cause of the variation, members of his party discovered ore just beneath the sod near what is now Negaunee, Michigan. Inventor-like, Burt’s only concern was to devise some preventive for future interference by stray magnetic currents. He simply noted in his book that there was here a deposit of iron ore and neither he nor any of his party profited or apparently attempted to profit from the discovery.

Showing Ore Body and Shaft Method of Mining

The Indians seem to have had no previous knowledge of these ore deposits.

The first shipments of ore naturally were samples taken from what afterward came to be known as the Jackson mine and trials of them in blacksmiths’ forges were made at Jackson, Michigan (from which town went the first seriously-minded pioneer, Philo M. Everett), and at Cucush Prairie. They were soon afterward tried in a blast furnace at Sharon, Pa.

The first plan was to build forges and manufacture iron near the mines. So there was established on Carp River a forge to which the ore was hauled in winter when the ground was frozen. It turned out, however, that while very good bar iron was manufactured here, it could not be delivered in Pittsburg at a cost less than $200 a ton. As the market rate for iron then was but $80 a ton the plan was not financially successful.

Lighting the Fuses in a Shaft Mine

Attention was turned to the shipping of ore to furnaces better located as regards coke supply and market. It was possible to make this a profitable undertaking only through cheap ore handling and transportation. So, to-day, the ore which is better adapted than the other raw materials for handling by labor-saving devices and transporting without deterioration, is taken to the coke and limestone, and to the market for the product. While the weight of coke used is but half that of the ore smelted, its greater bulk, loss by breakage when handled in quantities, and deterioration upon exposure preclude its manipulation in the way which would be necessary to get it to the ore.

View of Hull-Rust Mine, near Hibbing, Minn.

The marvelous development of this territory into the greatest ore producer of the world, including the hauling of the first small shipment on mule back, the building of the plank and then the “strap” railroad with grades so steep that the small trucks often ran over and killed the mules, the building of the steam railroad, the successive building and enlarging of canal locks at Sault Sainte Marie connecting for use of ever larger and larger ore boats the waters of Lake Superior and Lake Michigan, and the growth of ore boat fleets to such size that during the shipping season scarcely ever is one boat out of sight of another over the entire 800 mile journey from Duluth to the furnaces along Lake Michigan and Lake Erie, is within the memory of men still living. Marquette was the shipping point during the earlier days and the history of this and adjacent regions during the latter half of last century vies in pioneering flavor with the tales of our early western frontiers, and with the more recent Yukon mining camps.

The Routes by Which Lake Superior Ores Go to the Furnaces

The first two mines, the Jackson and the Marquette, have come to be particularly well known historically. The development of these and other ranges in northern Michigan and Minnesota, particularly the Menominee, Gogebic, Vermillion, etc., and, since 1890, the Mesaba and Cuyuna, have brought about revolutions in ore digging, handling and transportation, which followed each other with extreme rapidity. The ore carrying boats, for instance, may almost be said to have jumped from a length of three hundred to six hundred feet, and the Sault Sainte Marie canal locks were several times almost immediately outgrown, though rebuilt again and again, each time so much larger than before that they were deemed impossible to be outgrown.

Loading Ore at an Open Pit Mine

Showing Other Typical Ore Bodies, Shaft Mined

Practically all of the ore beds, with the exception of the Mesaba, yield hard or lump ores and most of them are shaft mines in which mining has to be done underground and the ore blasted down. Blast furnaces had never used any but lump ores when along came discovery of the immense soft ore deposits lying just beneath the surface of the ground over a region one-hundred miles long in what is known as the Mesaba district of Minnesota. These soft ores were so accessible and so rich that they drew the attention of the iron makers of the whole country. But, alas! While perfectly good in every other respect, they were merely dry powder and not adapted to blast furnace methods. There were great discussion, excitement, and ridicule among or at those who invested in these soft ore mines. Eventually, of course, blast furnace men worked out feasible methods of converting soft or what are termed “Mesaba Range” ores into iron in the blast furnace. Those brave spirits, who in the face of ridicule dared to invest in and develop Mesaba properties, have long been reaping their financial reward which still shows no sign of diminishing, as “Mesaba Range” mines are “the” mines of to-day.

A Close View of the Hoover & Mason Unloaders

While it may be done, it has not been found desirable to make up the entire “burden” or furnace charge of soft ores alone as long as lump or hard ores are obtainable to mix with them, but often more than half is soft ore.

Starting an Open Pit Mine. The Earth Covering is Being Removed

While ores from the shaft mines, called “Old Range” ores, are won by going down into the earth sometimes as far as 3,000 feet, drilling holes in the rock, blasting down the ore, and loading it into buggies which are hoisted to the surface, “Mesaba Range” ores are made available by simply “stripping” off the thin earth covering, then caving or loading with steam shovels the soft ore into railway cars. Some of the illustrations presented show the ore trains and shovels, and the manner in which the open pits are worked in terraces.

One naturally wonders how it is possible to mine and carry these ores to the shipping ports of Duluth, Superior, Two Harbors, Marquette, Ashland, Escanaba, etc., put them aboard ore carrying boats, transport them by steam power to Milwaukee, Chicago, Gary, Detroit, Cleveland, Pittsburg, Buffalo, and the many other iron centers and convert them into iron and steel at a profit. This, of course, is only possible because of the inventive genius of man. For every operation ingenious machinery has been constructed which has brought the cost of such operations to its lowest terms.

Unloading Cars of Coal or Ore is a Simple Matter with the Modern Car Dumper

Ore Cars are Unloaded by Gravity at Docks. The Chutes Then Convey the Ore from the Ore Pockets into the Boat’s Hold

By modern methods the cars carrying the ore from the mines are run up trestle-work into positions above the ore bins high over the docks. The mammoth ore carrying boats are merely steel shells with quarters for crew and machinery at bow and stern, and hatches built with exact twelve foot centers between. They are tied alongside the dock, long steel chutes, also spaced twelve feet apart, are lowered along most of the length of the boat and the ore slides into the vessel’s hold evenly all along as it has to do, else the buoyancy of lighter parts of the boat might break the frail shell. The entire load of 10,000 tons of ore is ordinarily taken aboard in less than one hour. Pulling out immediately the vessel traverses Lake Superior, the Sault Sainte Marie canal, Lake Michigan or Lakes Huron and Erie as the case may be, and ties up at the dock at destination. Years ago it would have been unloaded by men with buckets or wheel-barrows, requiring some days at best. Now, however, the hatches are uncovered and several ore unloaders with huge clam shell buckets taking as high as fifteen tons of ore at a “bite” descend like vultures upon it. Within four or five hours the boat is again empty with no manual labor having been done upon the ore from the mine to the furnace pile with the exception of a little heaping up of the ore in the corners of the boat’s hold, which the ore unloaders could not reach.

Hoover & Mason Unloaders at the Illinois Steel Co., South Chicago, Ill.

A young man named Alexander E. Brown could not bear, in the old days, to see the ore so awkwardly unloaded, and in 1880 started the procession of ore unloading devices. There are now several successful ore unloaders of which the Brown hoist, the Hoover & Mason, and the Hulett are probably the best known. With the Hulett unloader the operator has to be an aviator, as his position is directly above the grab bucket. He descends into the hold with the bucket, comes up with it and is with it in its entire journey from the boat’s hold to the dump and back again. It must be dizzy business.

The Hulett Unloader. Note the Operator’s Head in White Spot Just Above the Grab

Time is too precious to hold the boat at the dock long enough that each bucketful, large as it is, can go directly to its final bin. It is dropped just back of the unloading machine from which it is again picked up by other buckets which carry it back toward the furnaces and deposit it in cement ore troughs awaiting further journey to the ore house, from which it goes to the furnaces. The empty ore boat immediately coals with whole car loads of the fuel dumped into chutes leading to her bunkers by the car dumper and proceeds on her way back to the mines for another cargo of ore. The round trip, including loading and unloading, requires but seven days.

A Good View of the Hatch System of Modern Ore Boats and Four Hulett Unloaders at Work

As in many other lines of commercial endeavor of to-day, speed and large tonnage have been the aim and it would seem that in ore handling and conveying devices the limit has about been reached. The big steam shovels, gravity docks, ore tanks or boats, and unloading and coaling devices, with the low cost of water transportation have made our modern iron and steel preëminence possible. To show the importance to us of this water transportation, we might mention that the rate for carrying ore from Lake Superior ore ports to the Lake Erie furnaces has been as low as $.0007 per ton per mile while the transportation cost by way of a well operated railway at that particular time was more than $.005 per ton per mile—more than seven times as much.

The Rehandling Bridge with Stock Ore Pile and Blast Furnace at Rear

Though for some years past more than three-quarters of all of the iron ore used in the United States has come from seven or eight mines in the northern peninsula of Michigan and the adjacent part of Minnesota, it must not be understood that the Lake Superior mines are the only ore deposits in this country. Figures show that such an inference is far from the truth. It is true, however, that they have made the United States what it is, the leading iron producer of the world. There are still immense quantities to be mined on the Lake Superior ranges. Their heavy production of cheaply handled high grade ore has, of course, held back development of other districts, which also have great natural resources. The Birmingham, Ala., region for instance, is a great ore and iron producer, right now producing the third largest tonnage of any district in the country. Some time in the not far off future, Alabama with her great deposits of iron ore, coal, and other natural resources is going to announce herself in no small voice. New York, Pennsylvania, Tennessee, and Virginia rank next after Minnesota, Michigan, and Alabama as ore producers, and several other states of the Union are not paupers in resources of iron ore.

Hulett Grab Buckets in the Hold of an Ore Boat

We should not get so enthusiastic over our ore supply and iron production as to think that other countries are devoid of such material. Almost every civilized country has ore enough that it does pretty well. With many the trouble is that the ore has objectionable constituents or that supply of cheap fuel is not available. Germany has large deposits of iron ore, but until the invention of the basic Bessemer process about 1870 she was handicapped because of the high phosphorus content of her ore. The basic processes, both Bessemer and open-hearth, allow of the removal of this phosphorus during the conversion into steel, and they therefore brought Germany to the front as an iron producer.

The excellence of Sweden’s iron and steel has long been known the world over. Sweden produces approximately one per cent of the world’s total production of iron and steel, but her ore has been of such high grade that iron made from it has maintained its position as a standard for use in the manufacture of highest grade crucible steels. The very finest steels for cutlery and tools, and even the softer grades of steel of northwestern Europe, have been made from Swedish iron as a base.

Iron ore, of course, is classified by geologists and chemists into varieties with such names as hematite, magnetite, siderite, etc., which here little concern us.

To be worked at a profit, the iron content of the ore must be high with the smallest possible amounts of undesirable impurities, particularly phosphorus, sulphur, and silica. There are, however, certain impurities which are not undesirable, for instance, lime, which will act as a flux and neutralize the effect of some of the undesirable impurities. For these reasons the prices for iron ore are based on the iron content and modified by the relative amounts of undesirable and desirable impurities. Phosphorus is almost a domineering factor and at present approximately fifty cents a ton more is paid for Bessemer ore (that containing less than .050 per cent phosphorus) than for non-Bessemer ore. As might be expected the best ores have been the first used and the grade is constantly falling. Instead of the 66 per cent iron ores of some years ago those coming nowadays contain not much more than 59 per cent of iron and the Bessemer ores described above are getting scarcer, so that for some years practically all of the furnaces have been mixing with them as much higher phosphorus ore as could be used without pushing the phosphorus content of the mixture over the allowable limit.

We often hear people surmising what is to become of us when all of the iron ore of this planet has been used. There is no harm in taking stock of resources and in this case it does us much good. It happens that each time the count is taken of iron ore available and that which under future and better methods of working can be utilized, we find ourselves immensely better off than the previous report had made out and we have less cause to worry about the future. The last inventory was taken by the extremely ambitious International Geological Congress held at Stockholm, Sweden, in 1910. It shows that the world yet has enough rich ore to make 10,192,000,000 tons of iron, and, a further supply of ore for 53,136,000,000 tons of iron, which could be used if necessary.

So we will get along for a while yet.

CHAPTER III
THE OTHER RAW MATERIALS

Old Charcoal Kilns, near Negaunee, Mich.

Since the beginnings of iron manufacture, charcoal has been a favorite fuel. Though during the past two centuries coke has grown to be the standard, with anthracite and some few bituminous coals finding use in certain favored localities, charcoal may be considered the fuel which developed the iron industry, at least until recent years.

Charcoal

As most of us know, charcoal is completely charred wood, usually hard wood, though sometimes resinous or other soft woods are used. Of well-dried timber more than 50 per cent by weight is moisture. This and certain other constituents are driven off by heat in the absence of air, which process is usually called “destructive distillation.”

By primitive methods a considerable part of the wood was completely burned and wasted during the production of charcoal. Stacked in piles or long rows the cut wood was well covered with earth, except for a small opening at the top through which the fire was lighted down a center cavity left to the bottom of the pile. The air coming in through the opening at the top was sufficient to keep the wood smoldering. After a period, which had been shown by experience to give the best results, the opening was closed and the fire smothered.

Beehive Coke Ovens

Brick ovens of the beehive shape were built at a later date where considerable charcoal was to be made. These were operated on much the same general principle as the meillers or earth-covered piles, described above. The fire was lighted at the bottom of the central cavity of the corded wood, the only air at first coming from the top, though later in the process a little was admitted through holes in the walls. After about ten days, when gas ceased to come off, the kiln was tightly closed for a period of twenty days more for the fire to die out and the charcoal to cool.

By both of these processes valuable constituents were burned or driven off by the heat and lost. These were mainly methyl alcohol, acetic acid, and wood tar.

Modern industry so emphatically disapproves of any waste of materials that apparatus has been devised to produce charcoal which allows of recovery of the by-products at the same time. In northern Michigan, which is practically the only district in the United States in which the charcoal industry as an industry still survives, long steel tubes or retorts are built with brick fire-boxes under each end, much as a stationary boiler is set. Into these retorts are run steel cars loaded with the wood. The retorts being closed, the heat drives or distills off the moisture and gaseous compounds through pipes connecting them with condensing apparatus. After about twenty hours the wood has been charred, the doors of the kilns are suddenly opened and the cars are rushed into other and similar retorts for cooling, while fresh loads of wood replace them in the first.

Standard Beehive Coke Oven

Beehive Ovens

As may be surmised vast quantities of wood and of wood-producing land are required for extensive charcoal manufacture, and this is the most serious problem for the manufacturer of charcoal. Several square miles of timber land must be cut over each year and the wood efficiently transported in order to operate a large plant profitably.

Pig iron as a by-product is a rather novel idea, but that is practically what the charcoal pig iron produced in our Lake Superior region is. Several companies operate wood distillation plants for the production of methyl alcohol, acetic acid, acetate of lime, etc., and use their charcoal in the manufacture of charcoal pig iron from the ores so close at hand.

The very low sulphur content and the small amount of ash have been the great advantages possessed by charcoal over other solid fuels. Resulting characteristics made charcoal pig iron a former favorite for manufacture of certain articles such as chilled car wheels, etc., and it, therefore, brought a higher price than coke pig iron. During recent years, however, by careful selection of coal and improvements in the coking process the sulphur and ash of coke have been so reduced that charcoal has not so great an advantage as formerly. Charcoal iron to-day brings only about $1.50 per ton more than coke iron; whereas, the differential a few years ago was as great as $5.00 or $6.00 per ton.

Charcoal is quite fragile and structurally weak, so much so that blast furnaces for its use cannot be built higher than sixty feet; whereas, the great strength of coke allows them to be built to exceed one hundred feet in height with correspondingly increased output. What this means may be realized by every one conversant with the demands of modern industry.

Coke

Charging Coal into the Ovens

As charcoal is completely charred wood, so coke for analogy’s sake may be said to be completely charred coal, practically always of the bituminous type. By “baking” bituminous coal at a cherry-red heat, its volatile constituents are driven off as the well-known “coal-gas” of almost every small town, and a strong, brittle and porous material or coke residue is left. If the baking is done without any admission of air to the retort, practically none of the coal burns and the “cake” or coke which is left contains the ash of the original coal and what is known as the “fixed carbon,” i.e., carbon which cannot be distilled or driven off by heat alone, though it would burn were air admitted.

The gases or volatile constituents which are given off consist mainly of moisture and a mixture of gaseous chemical compounds, which are known as “hydro-carbons.” These contain that part of the carbon of the original coal which does not remain as “fixed carbon” in the coke.

Quenching after Coal Has Been Coked

Just why some coals will coke while others of apparently the same composition as shown by the chemist’s analyses, will not, but instead of the hard brittle mass will leave a heap of brown or black powder, is not as yet definitely known. It is easy enough for chemists to determine with accuracy the amounts of hydrogen, nitrogen, oxygen, carbon, sulphur, and other elements; but it is a difficult and perhaps an impossible matter to determine just how these elements are “hitched up” in the very complex mineral, coal,—one of the most complex substances which we know.

Various theories have been advanced in the attempt to explain the coking quality. A bulletin of the United States Geological Survey claims that the relative percentages of hydrogen and oxygen in the coal determines it; others have held that it depends upon the compounds of a tarry or asphaltic nature present. The fact remains that some coals coke without trouble, while others do not coke at all. As yet the only real way to tell whether a new variety of coal will or will not coke is to try it.

Since 1713, when Abraham Darby in England succeeded in introducing it as a substitute for the fast disappearing charcoal for use in blast furnaces, coke has become the standard fuel. It is very strong and will bear up under the great weight of iron ore and limestone with which the furnace is charged. So furnaces for use with coke may be built much larger than those in which charcoal is to be the fuel. The porous nature of coke allows it to burn rapidly with intense heat, so that the output of an iron works is greatly increased through its use—a very desirable thing in these days of big things. It has its disadvantages, of course, mainly high sulphur, a deleterious substance for which molten iron, unfortunately, has a voracious appetite, and a rather high percentage of ash which must be fluxed out. But all in all, it is a very desirable fuel for blast furnace and other metallurgical purposes, as is shown by the fact that it is used in the production of about ninety-nine per cent of all iron and steel now made.

Drawing the Coke

What is known as the Appalachian coal region produces coal for more than seventy-five per cent of the coke made in the United States. This region includes the strip of territory extending from Western Pennsylvania and Ohio down to Tennessee, Georgia, and Alabama. The famous Connellsville district is a part of this region.

Illinois and Indiana have a great deal of coal, which, however, has rather indifferent coking qualities. Almost constant experimentation has been carried on in the attempt to induce these semi-coking coals to coke. The best that has so far developed is the use of a considerable percentage of them in admixture with coals of good coking qualities. Such mixtures yield quite satisfactory coke.

The Beehive Oven Process

Large Pieces of Coke

In the old days there was no desire or incentive to avoid waste of coal resources. If during the coking process some air got into the oven and part of the coal was burned, or if all of the gas given off was wasted, it did not matter. There was plenty more of coal and the thing desired was to get the requisite coke in the quickest and cheapest way.

Where Coals Are Pulverized and Mixed for Coking

In Western Pennsylvania, Ohio, and Virginia, were great beds of high grade coking coal. In this region and particularly around Pittsburg, numerous blast furnaces and steel mills grew up. The coke for these was made in the most convenient way—in the wasteful beehive ovens.

Battery of By-Product Coke Ovens, Showing Gas-collecting Main

As the name signifies, these ovens or retorts are brick chambers shaped like beehives. In the larger plants they are built either in single rows against long hills or in double rows back to back. Over the tops of the ovens in each row runs a car called a charging “lorry.” Coal is poured from the bottom of this through a hole in the top of each oven while it is still hot from the preceding charge. No air gets in except that admitted through the hole in the oven top and a small slit left over the one side door, through which the coke is drawn when the coking process is finished. The heat of the oven starts the distillation of the moisture and the volatile compounds which escape through the hole in the oven top. The small amount of air admitted burns a little of the coal and gas and raises the temperature of the oven to that required for coking.

After 48 or 72 hours a spray of water is thrown in over the glowing coal to quench the fire. The partially cooled coke is drawn through the open door, sorted and loaded into cars for shipment.

Though this method of coking is a very wasteful one, it yet produces the larger quantity of the coke made in the United States. However, conditions are rapidly changing and it will not be many years before the much less wasteful “by-product” process gains the ascendency. By 1914 it had already come to produce about twenty-five per cent of the total coke made here, and since that date the percentage has been rapidly increasing.

The By-product Process

Top of Ovens with Charging Bin and Lorry at Far End

By this system of coking a greater yield of coke is obtained and most of the by-products are saved. The value of the latter depends largely, of course, upon local conditions, such as transportation, costs of the material, cost of labor, and available market for the coke oven gas. They are usually figured as having a value of $1.50 per ton of coal coked, equivalent to a total of $71,000,000 per year for the coal coked in the United States.

Lorry for Charging Coal into Ovens

The ovens and apparatus required are considerably more expensive, but, since this industry has developed in this country during the last twenty-two years to a point where one-quarter of all of the coke manufactured is made by the by-product process, there can be no doubt that it is a profitable proposition and that eventually the wasteful beehive ovens will be a thing of the past.

Practically all of the types of by-product coke ovens in use have been developed in Germany or Belgium, where circumstances forced earlier conservation of resources than in this country. The three best known types are the Semet-Solvay, the Otto Hoffman, and the Koppers—the latter a recent arrival. They differ mainly in details of construction and operation.

Machine for Pushing Coke from Ovens

In a general way a “battery” of coke ovens consists of from 40 to 80 long narrow brick-walled chambers placed closely side by side with heating flues or “checker-work” between them. The fire for the baking process is in these flues, which are interconnected, and the heat developed is sufficient to drive off the moisture and volatile substances of the coal in the narrow chambers just on the other side of the brick walls. Charging is done by a “lorry” as in the beehive process. After from seventeen to twenty-four hours at a red heat, the coke is “pushed” from the ovens, one after another, by an electric ram which enters at one end. The 30 × 7 × 1½ foot block of glowing coke emerges from the other end, where, breaking under its own weight into good-sized pieces, it falls into a steel car on a track just beneath. A spray of water quenches it and it is taken to the storage bins to be sorted.

Rich coal-gas is the main by-product. That which comes off during the first seven hours is the richest and has the greatest illuminating or “candle” power. After washing free from dust, tar, ammonia, etc., the gas is usually run into holders or tanks from which it is distributed for use for illuminating or for heating purposes. That which comes off during the latter part of the coking period has much less of those constituents which give illuminating value. It has good heat value, however, and as fuel is required for keeping the ovens up to the coking temperature, this poorer gas from the coking chambers is switched into and burns in the flues between the coking chambers as mentioned.

Thus the larger part of the gas is sold to customers, usually in the city near which the ovens have been located, and the poorer part is utilized in heating the ovens and the steam boilers which run the plant.

Quenching Car Awaiting Its Load

The coal tar, which the German chemists have made so famous through its manufacture into the almost endless variety of beautiful dyes, is another of the by-products which is recovered by this, but burned or lost in the beehive oven process. From a long main over the tops of the ovens which connects the gas pipes, the tar flows along with the gas to the scrubbing and gas cleaning plant, where by rather intricate operations it is freed from other substances.

In this country much of the tar is used for building purposes, etc., and some as fuel, but not much has been made into the chemical products for which Germany is so famous. For a long time a few dyes and other chemical compounds have been made here from coal tar. Since the early days of the war in Europe and the cessation of imports of such materials on this account, there has come about considerable expansion in their manufacture here; but it is doubtful if the time is yet ripe for a wholesale entry into the manufacture of these coal tar “derivatives,” especially the very extensive variety of dyestuffs.

Naphthalene and benzol from which many other chemical compounds as well as munitions of war can be made, are among the by-products.

Quenching the Coke

Most of the ammonia which the corner drug store sells, comes from the by-product manufacture of coke. The largest part of the ammonia which is produced in the process, however, is manufactured into sulphate of ammonia, a well-known fertilizer.

Coal

Anthracite or hard coal has been used in certain districts in the United States, especially in New Jersey and eastern Pennsylvania. It is not an ideal fuel as it is too solid to burn rapidly, spalls or cracks under heat and interferes with the blast. Since 1860 when coke became available here much less coal has been used, though some is yet used in admixture with coke. Some bituminous coals which contained little tarry matter also have been used in this way.

Fluxes

Limestone, the rock which is ordinarily used for fluxing purposes, needs no introduction to any of us. As the marble of statuary, the material of which oyster and other sea shells and the white tombstones of our cemeteries are composed, it is well known. Any of these varieties of the material may be used for fluxing purposes, but usually it is limestone which is quarried for the purpose or obtained as chippings or spalls from building blocks.

Coke Going from Quenching Car to Bins

Loading Coke in Box Car

The active agent, which produces the chemical or fluxing action in the blast furnaces, is carbonate of calcium (lime) of which limestone contains about 98 per cent. Dolomite is a mixture of carbonates of lime and magnesium, about 53 per cent of the former and 45 per cent of the latter, and is sometimes used in place of limestone. Fluor spar, a rock composed of calcium and fluorine, is used in small quantities in some of the metallurgical processes. It is a very powerful flux.

CHAPTER IV
THE BLAST FURNACE

Up the dark tower shoots the elevator with its “buggy” of coke. Its speed is not conditioned to the comfort of man, who is not supposed to be a passenger, except the occasional laborer whose duty as buggy-pusher requires his presence on twelve-hour shifts at the top. So we, whose exploratory proclivities have led us at the office to sign away our lives for grant of a pass to the blast furnace, find our breath about taken from us with the first mad dash into the darkness of the climb. That stone tower had looked much more innocent from below.

But now the rickety elevator has as suddenly emerged into the light again and stopped abruptly at the charging floor which extends across the chasm to the top of the furnace.

As the smoke-begrimed buggy-pushers rush the buggy of coke across to the furnace bell, we have opportunity to notice that we are a full hundred feet above ground. Just here, seemingly so close that we can put our hands on them, in a row, are the round steel tops of the four stoves which are for the purpose of preheating the blast. The huge pipes, dust arresters, tanks, and buildings, all so necessary to the plant, look almost like a tangled mass from our high station, while the charging floor upon which we stand, the shoulder-high steel fence around it, the furnace top, the adjacent stoves and in fact everything for a half mile around us, is colored yellow-red with iron dust. We understand the reason for this when the buggies of ore which have succeeded the coke are dumped into the funnel-shaped depression around the conical bell at the center. As the huge bell is lowered and the charge slides in there is considerable blowing out of the fine ore dust, which, in fact, continually “oozes” out of all crevices under the heavy pressure of the blast inside.

Hand-fed Blast Furnace

Day and night, month in and month out, during the life of the fire-brick lining of the furnace, this routine of charging, first coke, next the theoretically correct charge of analyzed iron ores, then limestone, in rotation goes on. From 6 A.M. to 6 P.M. and from 6 P.M. to 6 A.M. on twelve-hour shifts, alternating gangs of laborers push the buggies across to the furnace top, dump and return them to the elevator already up with another load.

The incessant quiver of the iron plates beneath our feet with the rumbling and groaning from the inside of this monster are disquieting and the thought constantly recurs: “What if this powerful creature should just now rebel, as quite occasionally occurred in the old days when all of its moods had not been so well understood?” For this king of metallurgical devices, though gentle and obedient as a lamb under proper treatment, is a domineering fury when it has dyspepsia as occurs whenever its attendants are remiss in their attentions to its diet. “Those explosion doors just below the furnace top—are they in working order and would they be adequate?” But whether, as in recorded instances, the whole furnace top is torn off as evidence of its wrath, or its displeasure is exhibited in a milder way, we much prefer to be absent. The thought is disquieting and we are glad to leave.

Cinder or Slag Flowing into Ladles

“Fireworks” at the Cinder-Notch

Unwilling to test again the elevator for the downward trip, we take to the narrow iron stairway which leads from the top of the furnace to the ground. But this is worse than the elevator, for the stair treads are very narrow and made only of three slender iron rods. To our palpitating hearts they seem to give very insecure foothold and the gaps show that there is nothing but earth beneath us, and that a hundred feet below. To make matters worse, before we creepingly get half way down some visitors below have stopped to watch our slow and trembling steps and our nervous clutch on the low “stingy” hand rail. We hear them innocently inquire of one another why we move so slowly. We wish that we could appear brave, especially before the women in the party, but we could not move with greater alacrity if our lives depended upon it.

Once below again with our breath regained, things are more interesting. The red-hot molten slag which has just been tapped out is running from the furnace along a long trough into a ladle six feet high resting upon a car on the railway track alongside the “cast house,” as the huge structure which houses the lower part of the furnace is called. This smoking, molten slag stream gives off a powerful sulphur smell and throws a lurid glare over everything round about.

The Slag Dump

The furnace superintendent is just explaining to the other party that No. 2 furnace has been “hanging” for a couple of days and is still dangerous. “If you realize,” said he, “the great weight of coke, ore, and limestone in that furnace, you can see what a splash it would make if the clogged, bridged part with all above it should fall suddenly into the molten pool in the ‘hearth’ of the furnace. Two years ago No. 1 broke out and the molten metal caught and burned to death one of our men and injured several others. ‘Hanging’ does not occur when the furnace is working right, but failure of the charge to come down evenly is very serious sometimes. A blast furnace is like a coquette; she has to be handled just so, and even then you cannot always be sure what she is going to do next.

“Oh yes,—where does the iron come from? Well, we often read nowadays of a man and his ‘affinity.’ Now the chemist has used that word ‘affinity’ for years to describe the liking or attraction of one chemical ‘element’ for another; in fact, that is where this recent colloquial use of the word originated. Iron ore is nothing more nor less than metallic iron, the element, chemically combined with oxygen, another element which constitutes one-fifth of the air we breathe. Under conditions produced in the blast furnace, though for centuries wedded to iron, oxygen deserts him for her ‘affinity’ carbon, which is best known to you as coke, coal, or charcoal. The iron, now free, becomes molten at the high temperature encountered (about 2800° to 3000° F.) and descends into the ‘hearth’ or bottom of the furnace, while oxygen and her new partner escape out of the top of the furnace in gaseous form. When molten iron has accumulated in the hearth to the extent desired it is tapped out as you will soon see.

Diagrammatic Sketch of Blast Furnace

“The limestone charged has ‘affinity’ for dirt and certain other impurities of the ore which it removes in molten form as the ‘cinder’ or ‘slag’ which is there running into the ladle. When cold, this cinder is a dark greenish-black, glassy substance, which of recent years has come to be used to a certain extent in the manufacture of Portland cement but is mainly used for filling-in purposes. Some is crushed and utilized in concrete mixtures and for road building. In Chicago considerable land has been ‘made’ by dumping slag into the lake, and South Chicago is reported as standing on a swamp which has been filled in with slag from the steel works there.

Old-Fashioned Pig Bed

“This immense furnace is simply a strong steel shell lined two or three feet thick with fire bricks. At the ‘bosh,’ which is the region where the greatest heat is produced, hollow bronze plates are inserted among the bricks of the lining through which circulating cold water keeps the bricks from being fused.

“The hot gases which are led from the upper part of the furnace through that brick-lined ‘downcomer’ are burning in three of those ‘stoves’ to heat them, while cold, clean air from the blowing engines is coming through the other stove, which, ten minutes ago, when it was put on blast, was the hottest of the four. It is now giving up part of its accumulated heat to the blast on its way to the furnace. Switching the cold incoming air every little while from a partially cooled stove through a hotter one while allowing the former to reheat, provides continuous blast of a temperature of 800° to 1400° F. The ‘hot blast’ idea originated about 1830 with James Neilson, a gas engineer of England, and its introduction revolutionized the blast furnace industry and made the highly efficient modern practice possible.

Furnace and Sand Bed Ready for Iron

“This big pipe above our heads which encircles the furnace is the ‘bustle pipe.’ It also has to be lined with fire bricks. The hot blast is distributed by this ‘bustle pipe’ to the tuyères here—these L-shaped pipes—which shoot it directly into the furnace. Through the peep-holes in the tuyères you can get a glimpse of the dazzling interior of the furnace. The blast of heated air is causing the coke to burn fiercely there so that it melts the iron, which farther up in the furnace has been forced to part from the oxygen, as I explained to you.”

Layout of Blast Furnace Plant

But now six men with a long steel bar are starting to break through the two or three feet of clay with which the “tap hole” of the monster furnace is plugged, and our informant hurries away.

Skip Hoist at Work. Skip Dumping into Hopper

For ten minutes with strong sledge blows the tappers struggle to break through the plug of burned clay. Meanwhile the monotonous whistle of the heavy blast into and through the bustle pipe and tuyères goes on and the discharge pipes of the water-cooling plates empty into the gutter around the furnace bottom the water which has been circulating to keep the inner bricks from fusing.

SECTION OF BLAST FURNACE SHOWING FILLING ARRANGEMENT, BINS AND ORE BRIDGE

And now a shout and the strong red glow throughout the cast house tell us that the tap hole is open and the iron is running down the main channel of the sand bed. Past the plugged entrances to the lateral branches runs the molten iron stream to the end of the cast house nearly one hundred feet distant where it divides, filling the laterals on each side and from them running into many open molds arranged like the teeth of a comb. Each of these molds is about five feet long. They form the “pigs,” and the laterals what are known as “sows.” As each lateral and its molds fill, the lateral ahead of it is opened and the process repeated, laterals and pigs filling up simultaneously on opposite sides of the main channel till the whole cast house floor is filled nearly up to the furnace with the red smoking metal.

Sand Cast Pig Iron

There are few sights more glorious than the cast house with bed just filling with metal, and especially is it so at night. The strong yellow-red light of the flaming metal issuing from the furnace and the intense glow of that already in the bed illuminates everything in and about the building. But already, before the furnace is empty, the workmen are spraying with water the earliest cast pigs. Covering them with a light layer of sand they venture upon them with thick-soled shoes and break the “pigs” from the “sows” with sledge hammers.

This is the old-fashioned “sand cast” pig iron. After remelting in the cupola furnaces of neighboring towns and casting into stove parts or other forms it is known as “cast iron”; through “puddling” in reverberatory or special furnaces it becomes “wrought iron”; after decarbonizing treatment in steel furnaces of various design it is changed into the wonderful material called “steel.”

Pig iron is thus the intermediate or semi-raw material from which practically all of our various iron and steel products are made and the transition product through which they pass.

Machine Cast Pig Iron

But the romantic period of the hand-fed furnace and the gloriously beautiful pig beds at casting time are rapidly passing; in fact, are almost past. Modern “skip-hoists” carrying automatically dumped buckets or cars charge the furnace more economically than even low-waged laborers can do it. The two charging cars alternate, one filling at the bottom in the stock house while the other is dumping through the double bell at the top of the furnace. Furnaces are now tapped by power driven drills which make quick work of a formerly difficult operation. Instead of running it into the sand bed, the molten iron from the furnace is nowadays run into ladles alongside the cast house as is the cinder which was described above. If the metal is to be made into pigs it goes to the pig casting machine, where the traveling iron molds very quickly convert the entire cast into “chilled cast” pigs. At the top of the incline these pigs which have been cooling under sprays of water fall from the traveling molds into railroad cars below which deliver them to the consumer.

How Pig Iron Is Now Cast into Traveling Molds

Upper End of Casting Machine Where Pigs Are Dumped from Traveling Molds into Railway Cars

In large steel works the greater part of the molten iron is not cast into pigs at all but while yet molten is directly charged into the open-hearth or Bessemer furnaces which convert it at once into steel of which the greater part is made into plate, rails, or other shapes before being allowed to cool. Even the gas is recovered nowadays. Its journey through the “dust arrester” rids it of most of its dust, after which filters and washers clean it thoroughly. That not required for the heating of the stoves is used for firing the steam boilers about the plant and as fuel for batteries of huge gas engines which in large plants have been installed to generate low-priced electric current.

It should be noted that in modern practice iron is mined, loaded, transported to the furnaces, unloaded, charged and made into pigs or converted into steel and even into the finished products with practically no hand labor, all operations being performed by machinery.

Though a “direct” process for converting the ore into wrought iron or steel has been long sought, a method has never been found, except that used in the very small way followed by the old iron-workers with their crude furnaces. It has always proved commercially advantageous to make pig iron in the blast furnace as an intermediate step and then by a second step convert it into wrought iron, steel, etc. So the ore is brought from the mines to the furnace, the coke and limestone arrive from another region, and batteries of huge blast furnaces through the country make from them the pig iron.

[1]. No advantage has been found in furnaces having a height of over 110 feet.