September, 1926
INDUSTRIAL A X D E,VGINEERING CHEMISTRY
000 barrels and was valued a t more than $250,000,000. It is natural, therefore, that the contribution of America to the technology of cement, made entirely during the last fifty years, should be towards economic quantity production, and incident to this notably the invention of the dry process,
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the successful application of the rotary kiln, the use of pulverized fuel for heating the kiln, the development of large units for crushing and pulverizing, the utilization of the waste heat from the kiln for power generation, and the automatic sacking of cement.
The Steel Age-1876
to 1926’
By John A. Mathews CRUCIBLE STEEL COMPANY OF AMERICA, NEWYORK, N. Y.
HE writer’s recollection of the “Centenilial” centers around some toy ducks, swans, and fishes that swam about in a tub of water obedient to a small permanent bar magnet. Then there was a popgun, which probably accounts for my militaristic tendencies. Such war-breeding toys should not be given children! We should have a Constitutional Amendment forbidding them and my fond but thoughtless aunt-herself an educator-should have known better than to bring me a gun-pop or otherwise. It is well nigh impossible for the children of today to comprehend the amazing developments of the past half-century. They take for granted the telephone, electric light, and radio; the trolley-car, automobile, and airplane; yet probably the youngest member of the AMERICAN CHEMICAL SOCIETY has lived through a period in which the production of iron and steel has exceeded that of all previous centuries. The history of iron, however, goes back to remote antiquity, or possibly to twice the age of the Christian era. When steel replaced wrought iron quite generally as a metal of construction, a great advance occurred, and this dates approximately from the year 1876, and the period since may quite appropriately be called the Steel Age. That was the last year in which the iron railroad rail exceeded the production of the steel rail.
T
Steel-Making Prior to 1876
Steel and steel-melting processes were not new. The venerable crucible process is nearly two hundred years old; it could never be the basis of a “tonnage” industry, but as a “quality” method it has not yet been surpassed. The Bessemer and the Siemens-Martin processes came along in the late sixties and these gave the real tonnage impetus and challenged the position of wrought iron. There was strong prejudice to be overcome and no doubt much of it justified by difficulties encountered in the operation of radically new methods. It must be remembered that routine chemical analyses were not customary when these methods began and chance selection of ores was the controlling influence in most cases and meant the success or failure of local enterprises. And they were local enterprises too, for the great transportation systems were lacking and the small plant serving a local district flourished in many states and a t a still earlier date was sprinkled over the colonies. In Pennsylvania alone there were about 275 furnaces as late as 1876, and since that their number has declined but the capacity of the individual unit has steadily increased. The blast furnaces a t that time used anthracite, raw bituminous, coke, and charcoal as fuels; over half of them used anthracite, while coke furnaces were even then in excess of charcoal furnaces. All steel made prior to 1876 was “acid;” that is, the crucibles or furnace linings were of siliceous material. Such furnaces are primarily melting and not refining furnaces. To make good steel in them requires good raw materials and these are 1
Received June 8, 192G.
not so abundant as we might desire, while vast quantities of ores too high in phosphorus for acid steel were useless. Just a t this time the “basic,’ process was being developed, by means of which not only Bessemer but also open-hearth steel and pig iron could be dephosphorized and mountains of ores became available. The use of basic linings of magnesite and dolomite and strongly basic lime slags accomplished this and gave to the steel industry its strongest stimulus toward quantity production. The basic process created the Steel Age. With this began the day of big things-big furnaces, big mills, big companies later becoming big corporations, big buildings, big ships, and big guns. In 1876 iron was on the decline, and all steel was of acid manufacture, but although experiments were in progress the basic process had not been announced or patented. Barbed wire and wire nails were new inventions; experiments with ship plates of steel had been made, but no large vessels entirely of steel had been built; steel for bridges was just being introduced, iron being entirely used in the great Girard Avenue Bridge in Philadelphia of 1874, while the Eads Bridge a t St. Louis used some steel; the “skyscraper” was unknown. The blast furnace of that day produced between 50 and 75 tons per day. The United States had produced pig iron a t the rate of 2 million tons a year somewhat prior to 1876 and nearly one-half of it was made in Pennsylvania, the old furnaces in the eastern part adhering to anthracite, while the Pittsburgh district was developing coke fuel. Soft Bessemer steel was substituted for wrought iron for tin-plating, and the new Edgar Thompson Steel Company showed a t the centennial exposition a 62-pound rail 120 feet long, a record length a t the time. Chemical control methods in plants were almost unknown and the metallurgist as we know him today was not in evidence. Empirical methods prevailed, but that does not mean that the steel was not good. These pioneers were steel-makers and would not have recognized themselves if called “metallurgists.” Practice was far in advance of theory. The microscope, the pyrometers, scientific heat treatment, hardness testing, and the underlying chemistry of processes had yet to receive recognition in the industry. Development since 1876
The years between 1876 and 1926 have been years of development and growth rather than years of invention or discovery of fundamentally new processes. The basic process is the great exception, and the introduction of electric furnaces about 1900 really represents the development of electrical generating methods and the reduction in the cost of wholesale power; they are either basic or acid in character and, while permitting of certain reactions that cannot be carried out in the older processes, their metallurgy is not very differentfrom that of the open hearth except for the use of the reducing slag. Steel was melted in the electric arc long before it was a commercially feasible thing to do. This period
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INDUSTRIAL AND ENGINEERI,VG CHEMISTRY
has also been characterized by intensive experimentation and research. Alloy steels were all but unknown in 1876, even though Michael Faraday produced many of them more than a hundred years ago, as did also Gautier and other French chemists. The introduction of commercial alloy steels to a large extent had to await the production a t low cost of the metals or ferro-alloys used in their production, and the electric furnace has been of inestimable value in this regard. When chemical methods became general, chemical analysis received undue attention, and the cause of most steel troubles was sought and supposedly found in minute chemical differences. Sulfur and phosphorus particularly were blamed for all kinds of troubles, and copper was under suspicion for many years, to be called upon when the sulfur and phosphorus could not be accused as a cause of failure. NOWwe have individual metallurgists and national committees trying to “clear the names” of these unfortunate metalloids, or a t least to find out just how bad they are. To do so the newer methods of metallurgical research are employed; mechanical tests of all kinds-fatigue, shock, etc., and the microscope, up to 5000 diameters magnification-must be invoked. The same old troubles with steel are still with us, but we don’t talk so much about sulfur and phosphorus as about sullide inclusions, oxides, ghost lines, hair lines, which expressions frequently answer for “explanations” when we don’t perhaps know the reason. Metallurgy is now in the position that chemistry formerly occupied and metallurgicrtl minutiae take the place of chemical minutiae in the search for what’s what. In the meantime there is an increasing recognition of the fact that more important causes must be studied and that these can best be attacked by physico-chemical methods. Equilibrium conditions are not easy to study in 100-ton open hearths or 600-ton blast furnaces and in systems of many variables a t temperatures of over 1500” C. Nevertheless, there are pioneers who are making the attempt and to their efforts we must look for explanations that really explain. They have not a great background of standard data as to solubilities, specific heats, vapor tensions, etc. Their problems are extremely difficult and not only the iron and steel industry but all industries should appreciate the importance of the task. When metallurgy rests upon a sound physicochemical foundation, hair-splitting arguments on micro and macro structure will not be so frequent, for we shall have a sounder knowledge of what these really represent. Scientifically we have developed methods of tests faster than we have learned to interpret properly the results of our tests, and the year 1926 finds us in some confusion on this account. We are inclined to place undue stress upon things that may some day prove of minor importance when the underlying chemistry of all the metallurgical reactions is known. Fuels for Steel Production
The evolution of blast furnace fuels is interesting. Charcoal was the principal fuel for centuries, and in America it was but natural that it should be used, for timber was plentiful and much of it had to be cut to clear the soil and for building. Both raw coal and coke, however, had been used, for smelting iron ores prior to 1651, but in this country charcoal was first used exclusively and it was not until 1855 that anthracite iron passed charcoal iron; in 1869 bituminous fuel also passed charcoal, but taken together they only equaled the production with anthracite coal. In 1875, bituminous fuel passed anthracite and has now become the principal fuel. Originally this was all beehive coke, but this reached its maximum production in 1916, only to be passed by by-product coke in 1919, and today only one-quarter of the coke used is
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from beehive ovens. By-product coke making has increased fortyfold in twenty-five years. For the last year the figures are available, over 49 million net tons of coal were used in by-product ovens and the by-products had a value of $103,840,550, or about one-half the value of the coal used. In heating and melting furnaces the fuels have included charcoal, coke, raw coal, producer gas, natural gas, crude oil, tar, powdered coal, and electricity. Status of Industry Today
Obviously, the statistical data for 1926 are not available, but certain trends may be noted. Bessemer steel held on tenaciously, especially for use in rails up until 1911. Then basic open-hearth rails took the lead and now represent about 96 per cent of all rails made in this country, and of these rails over 60 per cent are of the class of 100 pounds per yard or over. Rails alone represent a larger tonnage than our whole production of pig iron fifty years ago. Pig-iron production has increased twentyfold in fifty years, and has once passed 40 million gross tons, of which over one-half is basic iron and one-quarter Bessemer and low phosphorus. Charcoal iron has all but disappeared and represents but 200,000 gross tons of the total, while anthracite iron does not appear in the latest figures. Of all the pig iron made three-fourths is for consumption by the makers, mostly for steel-making, and the balance is for sale. Of the iron used directly twothirds was delivered in the molten condition, while of the basic iron about 80 per cent was delivered in the molten condition. The world’s production of pig iron for last year was 75 million tons and of this the United States produced 48.5 per cent. For most of the period between 1876 and 1926 the United States production has been greater than that of any single nation; for about half that period it has exceeded that of our two greatest rivals, while in several recent years it has been more than 50 per cent of the world’s production. Our tremendous home market and cheap and abundant ores and fuels account for this wonderful growth, since our export trade is relatively smaller than that of some other nations and not a very high percentage of our own total output. Lake Superior ore shipments were about 1million gross tons in 1876 and over 55 million in 1925. In the former year only the Marquette range had been developed, followed by the Menominee in 1877 and, in order, by the Vermillion, Gogebic, Mesabi, and the Cuyuna as late as 1911. These have now produced more than 1,250,000,000tons of ore. The figures are hard to grasp and in this brief review as few figures as possible have been used to convey an idea of the marvelous growth of the iron and steel industry. All metallurgy is a branch of applied chemistry and the chemists have much to their credit for this growth. The great basic process was a triumph of chemical investigation and, as has been said, this was the foundation of the growth of steel production since the late seventies. High-phosphorus slags are useful fertilizers and a great cement industry has sprung up as a by-product of the iron industry. American chemists have contributed many rapid and accurate analytical methods that are used throughout the world. Control methods have helped to improve quality, keeping step with increase in quantity; in fact, the improvement in qualities has been a great credit to the technologists of all kinds, keeping pace with the ever-increasing exactions of industry, especially for the automobile and airplane. The mechanical man and the metallurgist, the chemist and the capitalist, may each have his own opinion as to his importance in the bringing about of the “Steel Age,” but the fact of the matter is that splendid COoperation of all was necessary along with the aid of the most productive labor in the world.
