Popular Science Monthly/Volume 38/February 1891/The Development of American Industries Since Columbus: Iron and Steel Industry III
III. IRON-SMELTING BY MODERN METHODS.
By WILLIAM F. DURFEE, Engineer.
THUS far in these papers we have dealt only with iron smelted by charcoal, and, in fact, up to the year 1830, there had been no attempt whatever to utilize either anthracite or bituminous coal for the purpose. In regard to the use of mineral coal Swank quotes as follows from a letter dated March 18, 1825, from the acting committee of the Pennsylvania Society for the Promotion of Internal Improvements to William Strikeland, who was its European agent: "No improvements have been made here in it [the manufacture of iron] within the last thirty years, and the use of bituminous and anthracite coal in our furnaces is absolutely and entirely unknown. Attempts, and of the most costly kind, have been made to use the coal of the western part of our State in the production of iron. Furnaces have been constructed according to the plan said to be adopted in Wales and elsewhere; persons claiming experience in the business have been employed; but all has been unsuccessful." In the year 1835 the Franklin Institute offered a gold medal "to the person who shall manufacture in the United States the greatest quantity of iron from the ore during the year, using no other fuel than anthracite coal, the quantity to be not less than twenty tons." This medal was never awarded, and it is fair to presume that the required quantity of iron was not manufactured by any one person in 1835 by "using no other fuel than anthracite coal." Nevertheless, there is abundant evidence to prove that from the year 1830 to the year 1840 there were a number of attempts to use mineral fuel for the smelting of iron-ores.
The most successful of these experiments was tried at Pottsville, Pa., and the works were called the Pioneer Furnace. It was built for Burd Patterson, by William Lyman, of Boston, and blast was unsuccessfully applied July 10, 1839, but the furnace was finally successfully blown in by Benjamin Perry, October 19, 1839, and produced twenty-eight tons per week of good foundry iron. "This furnace," say Bishop, "made a continuous blast of ninety days, and secured for its proprietor a premium of $5,000 which had been subscribed by citizens of the State." On June 5, 1839, Mr. David Thomas, who had been associated with Mr. George Crane in making pig iron with anthracite coal at Yniscedwin, in Wales, arrived in America, and on July 9th of the same year he commenced the erection of the first furnace of the Lehigh Crane Iron Company at Catasauqua, Pa. This furnace was successfully blown in by him on the 3d of July, 1840, and the first "cast" was made on July 4th. The furnace was provided with a hot blast, and was blown by water power derived from the Lehigh Canal. This enterprise was a success from the start, the furnace producing fifty tons of good foundry iron per week, and it continued to be profitably operated until 1879, when it was torn down. Notwithstanding the fact that there were several promising experimental attempts to smelt iron with anthracite coal prior to the erection of a furnace at Catasauqua by Mr. Thomas, yet this furnace, from its large initial output (as measured by the practice of the time) and continuous operation, and the fact that it pointed out clearly the essential requisites of success in smelting with anthracite coal viz., large capacity of furnace, supplied with abundance of blast at a high temperature—may fairly be considered the first furnace in America that achieved a satisfactory commercial success in making iron with anthracite as a fuel. From his success in the erection and operation of this furnace, and subsequent life-long identification with the manufacture of anthracite pig iron, on a scale far surpassing any of his contemporaries, Mr. Thomas is fairly entitled to be called the father of the anthracite iron industry of America. He died at Catasauqua on June 20, 1882, in his eighty-eighth year.
Fig. 31 is a view of the first furnace erected at Catasauqua by Mr. Thomas. This furnace was about forty feet square at the base and forty feet high; it was twelve feet internal diameter at the "boshes" and was lined with nine-inch fire-brick brought from Risca, in Wales. The hearth was four feet square. At first the "hot-blast stoves" were on the ground and fired with coal; they were three in number, and each contained two "bed pipes" connected by ten semicircular "siphon pipes." Each "stove" had a fire-grate at one end, and at the other was a chimney provided
Fig. 31.—Early Anthracite Iron-Furnace at Catasauqua.
with a damper at its top. The gas escaped freely at the "tunnel-head," and was, of course, wasted. The first blowing machinery comprised a "breast" water-wheel, twenty-five feet long and twelve feet in diameter; this operated two blowing cylinders five feet in diameter and six feet stroke. At first the pressure of blast was only about a pound and a half, but the following year another water-wheel of the same size was added, after which the pressure of blast was increased to two pounds and a half per square inch. The head and fall of the water-supply was eight feet, the "head-race" taking its water from above the lock opposite the furnace, and the "tail-race" discharging into the lower level of the canal, below the lock. With one water-wheel the "make" of iron was only about twenty-five to thirty tons per week, but with the second wheel the production was increased to upward of forty tons, varying, of course, with the condition of the water-supply, and sometimes reaching sixty to seventy tons. In years afterward this furnace, with still more powerful blowing machinery, made one hundred and seventy-two tons of iron in a week. The furnace was filled by a water hoist, consisting of two "tubs" about six feet square, suspended to a chain passing over a large pulley at the top of the hoist tower; the tops of these tubs
Fig. 32.—A Charcoal Blast-Furnace.
were covered and formed platforms on which the barrows were raised. By letting the water out of the tub that chanced to be at the bottom of the tower, the weight of water in the tub at the top caused it to descend, thus raising the other tub with its load. In order to operate this hoist, it was necessary to have a water-supply at the top of the furnace to fill the tub that was at the top. At first nothing but the coal was dumped into the furnace, the ore and limestone being charged with iron pans similar to the baskets formerly used at charcoal furnaces; the limestone was broken quite small.
After the success of this furnace was assured, furnaces in which mineral fuel (either anthracite or coke, or a mixture of the two, with an occasional use of raw bituminous coal) was exclusively used rapidly increased. Various changes and improvements naturally took place as time passed and experience was gained; but year by year the volume of iron smelted by mineral fuel increased relative to that made by charcoal, until in 1889 it reached the grand total of 7,871,779 tons, while "the make" of the charcoal furnaces amounted to but 644,300 tons.
Notwithstanding the practical demonstration by David Thomas that mineral coal could be successfully used for smelting iron, charcoal furnaces continued to be built. The general appearance of such furnaces as were erected during the fifteen years following the year 1840 is well represented in Fig. 32, of which Fig. 33 is a vertical section. As a rule they were no better in idea, and but little in execution, than those described by Swedenborg a century before; but, after the year 1855, the construction of furnaces began to receive more careful attention, and by the year 1860 the best-informed metallurgical engineers (whose profession was just beginning to be recognized) had discovered that uncouth bulk and crude workmanship were not desirable features in a furnace for the making of pig iron. Yet, nevertheless, some of the stragglers who are always found hovering in the rear of the grand army of progress, and who never know what is going on at the front, built furnaces, as late as 1864, that, when measured by the standard of the available knowledge of the time, were little better than ponderous aggregations of ignorance and masonry.
Among the earlier of the many improvements in the details of blast-furnace construction and management, which were made in consequence of the employment of mineral coal for smelting, was
Fig. 33.—Vertical Section of a Charcoal Blast-Furnace.
the substitution of blowing cylinders of iron for the wooden blowing apparatus previously employed in connection with charcoal furnaces. One of the simplest forms of iron blowing machinery is shown in Fig. 34. This apparatus consisted of two vertical "blowing cylinders," provided with appropriate valves, through which the air was drawn in and discharged into a "wind-chest" by the vertical reciprocation of a piston in each cylinder. These pistons were actuated by the cranks on the gear-wheel shown, through the intervention of suitable connecting-rods and walking-beams. The cut (Fig. 34) conveys only the simplest form of the idea embodied in the walking-beam blowing-engine, and is very far from adequately representing the latest exemplification of that idea, as carried out in the colossal machines employed to blow many of the largest modern furnaces.
There is great variety in the construction of blast-heating apparatus, but it can be comprehensively described as consisting of
Fig. 34.—Iron Blowing-Engine.
two well-defined types: (1) those forms in which the air is heated by passing through hot iron pipes, inclosed in a brick chamber or "oven"; (2) those forms in which the blast is heated by actual contact with red-hot masses of brick-work inclosed in air-tight chambers. Fig. 35 is a vertical longitudinal section, and Fig. 36 a vertical transverse section, of one of the best of the many forms of the first-named type of "hot-blast stove." This construction of "stove" was the invention of John Player, of England, who introduced it to the notice of American iron-masters in 1807; and the first "Player stove" in the United States was erected at the anthracite furnace of J. B. Moorehead & Co., at West Conshohocken, Pa. Before Mr. Player came to America it had been the usual though not universal practice to place the gas-fired "hot-blast stoves," as well as steam-boilers, on the same level as the top of the furnace, but in all the furnaces erected by him he placed the "hot-blast stoves" and the boilers on the ground, and brought the gas down to them in a large pipe or "down-comer" as it was called.
The "Player stove" was provided at its base with a large "combustion chamber" (see Fig. 35), into which the gas entered, and there meeting with sufficient air for its combustion, the resulting heated gases passed upward through flues (indicated by the arrows s, s, s) in the roof of the "combustion chamber" into the "pipe chamber" above. In this chamber were arranged a series of vertical "siphon pipes," standing upon hollow bases or
Fig. 35.—Longitudinal Section of the Player Hot-blast Stove.
"bed pipes" of cast iron. The air to be heated was admitted to the right-hand bed pipe B (Fig. 36), and passed thence in the direction of the arrows through the siphon pipes into the left-hand bed pipe B', from one end of which it was taken in suitable pipes to the furnace. The introduction of the "Player stove" was the means of greatly increasing the production of iron in the furnaces to which they were applied, and at the same time the amount of fuel required per ton of iron was diminished; further economies were realized by increasing the size of furnaces, and the power of the engines that supplied them with blast.
The first example of the second type of hot-blast stove erected in America was put in operation June 18, 1875, at Rising Fawn Furnace, in Dade County, Ga. The particular construction there used was that invented in England by Thomas Whitwell. Its general idea involved a cylindrical air-tight chamber of boiler iron lined with fire-brick; this chamber was traversed by a number Fig. 36.—Transverse Section of the Player Stove. of vertical parallel walls or diaphragms, also of fire-brick. The operation of this stove was as follows, viz.: The whole interior was heated to a very high temperature by means of the waste gas of the furnace which passed through the stove in the spaces between the fire-brick diaphragms. As soon as the stove was sufficiently heated the gas was turned off, and the blast was forced through the stove; and, as it traversed the spaces between the fire-brick walls on its way to the furnace, it absorbed heat from them and consequently reduced their temperature. This alternate heating and cooling of the stove, by the passage for a certain time, first of ignited gas, and then by the air to be heated, could be so regulated by suitable valves that a temperature of blast could be attained much higher than was possible in an iron-pipe stove. In order to insure regularity of working and uniformity of heat, it is usual to have at least three (some furnaces have four, and in Europe five have been used) such stoves to each furnace.
Besides the Whitwell stove, there are at present a number of others of the second type in use, whose details differ somewhat, but they all have an air-tight chamber lined with fire-brick, as a common constructive feature; this chamber is filled with partitions, blocks, tubes, and perforated or loose brick, in a great variety of ways, for each of which is claimed peculiar merit by its inventor; but it is quite evident that the design of some of these stoves was inspired by the desire to avoid the consequences of infringing existing patents on tweedle-dum by constructing tweedle-dee.
A good idea of the internal arrangement of a Siemens-Cowper-Cochrane Stove is conveyed by Fig. 37, in which, the burning gases intensely heat the reticulated mass of fire-bricks B B, which in turn heat the air of the blast. All the fire-brick stoves are of such huge proportions that a modern furnace plant suggests a hot-blast apparatus with an attached furnace, rather than a furnace with hot-blast stoves.
Raw bituminous coal has been used to some considerable extent as a blast-furnace fuel since 1845, near the end of which year Mr. David Himrod (late of Youngstown, Ohio) used raw coal for a Fig. 37.—The Siemens-Cowper-Cochrane Hot-blast Stove. time with success in a furnace on Anderson's Run, Mercer County, Pa. This furnace had been "blown in" with charcoal, but the available quantity of this fuel being insufficient, some coke was mixed with it, and later raw coal was substituted for the coke; and we are told that "the furnace worked well and produced a fair quality of metal." The first furnace in America built with the intention of using raw bituminous coal as fuel was built in 1845 for Messrs. Wilkinson, Wilkes & Co., at Lowell, Mahoning County, Ohio. This furnace was successfully blown in with raw coal on the 8th of August, 1846, by John Crowther, an Englishman, who came to the United States in 1844, previous to which he had been the manager of seven furnaces in Staffordshire. Mr. Crowther adapted many furnaces in Ohio to the use of bituminous coal, and instructed his three sons, Joshua, Joseph J., and Benjamin, in their management. He died April 15, 1861, in England. The successful blowing in of the furnace at Lowell may be fairly regarded as the commencement of the use of raw bituminous coal as a blast-furnace fuel in the United States.
Coke is the fuel by which over one half of the pig iron made in America at the present time is smelted. The first public mention of coke as a possible substitute for charcoal in American blast-furnaces is contained in an advertisement which appeared in the Pittsburg Mercury of May 27, 1813. This is quoted by Weeks, as follows, viz.:
"To Proprietors of Blast-furnaces:
"John Beal, Iron Founder.
"N. B.—A line directed to the subscriber, post-paid, will be duly attended to."
There is no evidence that Mr. Beal was ever called upon to "instruct" the Pittsburg iron-masters of seventy-seven years ago in the art and mystery of making "coak" but doubtless his advertisement may have stimulated inquiring minds; for, four years after its appearance, we find that Colonel Isaac Meason used coke in the "refinery" of his mill at Plumsock, Fayette County, Pa. This mill went into operation in September, 1817, and it was the first mill west of the Alleghany Mountains in which iron was puddled and rolled into bars. Weeks, speaking of the use of coke in this mill, says, "This is the first definite statement that I have been able to find of the use of coke in this country." A short time after this first use of coke in America there were several attempts to employ it in a blast-furnace, but there is no record of any success in this direction until the building of the Lonaconing furnace, Alleghany County, Md., in 1837. This furnace was (according to Overman ), "the first coke furnace whose operation was successful erected in this country. It is fifty feet high, fifty feet at the base, twenty-five feet at the top, and measures fifteen feet at the boshes." In 1840 two large blast-furnaces were built by the Mount Savage Iron Company, at Mount Savage, Md. These furnaces also used coke, of which there-was made, "from 1840 to 1850, between 50,000 and 75,000 tons"—"most of which was used at the furnaces." All the coke for the above furnaces was made in pits.
The manufacture of "Connellsville coke," which is regarded as especially excellent for smelting iron, was commenced in 1841. Weeks (writing in 1883) gives the following account of the beginning of the coke business in the Connellsville region: "Two carpenters, Provance McCormick and James Campbell, overheard an Englishman, so the story runs, commenting on the rich deposits of coal at Connellsville, and their fitness for making coke, as well as the value of coke for foundry purposes, and they determined to enter upon its manufacture. Mr. McCormick, who is still living, an old man of eighty-four, has given me an account from memory of this enterprise which I quote: 'James Campbell and myself heard, in some way that I do not now recollect, that the manufacturing of coke might be made a good business. Mr. John Taylor, a stone-mason, who owned a farm on which the Fayette Coke-works now stand, and who was mining coal in a small way, was spoken to regarding our enterprise, and proposed a partnership—he to build the ovens and make the coke, and Mr. Campbell and myself to build a boat and take the coke to Cincinnati, where we heard there was a good demand. This was in 1841. Mr. Taylor built two ovens. I think they were about ten feet in diameter. My recollection is that the charge was eighty bushels. The ovens were built in the same style as those now used, but had no iron ring at the top to prevent the brick from falling in when filling the oven with coal, nor had we any iron frames at the mouth where the coke was drawn. In the spring of 1842 enough coke had been made to fill two boats ninety feet long—about eight hundred bushels in each—and we took them to Cincinnati, down the Youghiogheny, Monongahela, and Ohio; but when we got there we could not sell. Mr. Campbell, who went with the boats, lay at the landing some two or three weeks, retailing one boatload and part of the other in small lots at about eight cents a bushel. Miles Greenwood, a foundryman of that city, offered to take the balance if we would take a small patent flour-mill at $125 in pay, which Mr. Campbell did. He shipped it here. We tried it, but it was no good, and we sold it to a man in the mountains for $30; and thus ended our coke business.' These gentlemen lost heavily in their venture. It was not until the Baltimore and Ohio Railroad was completed to Pittsburg, and Connellsville coke had been used successfully in the Clinton Furnace of Graff, Bennett & Co., at Pittsburg, that its value as a furnace fuel was thoroughly demonstrated and the foundation laid for the demand that has resulted in such a development of the coke manufacture in the Connellsville region. This furnace was blown in, in the fall of 1859. The coke was at first made from Pittsburg coal, near the furnace on the south side of the Monongahela River, nearly opposite the Point, at Pittsburg. The furnace was run for about three months, when, the coke made in this way not proving satisfactory, it was blown out, and arrangements made to secure a supply from the Connellsville region. The furnace blew in again early in the spring of 1860, the coke used being from the Fayette Coke-works on the Baltimore and Ohio Railroad, made at first on the ground in pits. The result was so satisfactory that thirty ovens were built in 1860, and arrangements were made to secure a continued supply."
The general tendency toward improvement in all branches of manufacturing that began to manifest itself in America about the year 1840, and which, fortunately for the welfare of the country, has grown with the years and strengthened with each new triumph of inventive thought, prompted investigation with a view to determine what constructive ideas were really essential to the building of a thoroughly efficient blast-furnace in which coke was to be used as the fuel; and it was very soon ascertained that European metallurgical engineers had discovered that it was not at all necessary to purchase a stone quarry before commencing the erection of a furnace, and that all the functions of successful smelting could be performed in a structure consisting substantially of a sheet-iron casing lined with fire-brick, supported upon cast-iron columns, between which were the tuyères and dam, which were thus rendered readily accessible; the furnace being entirely unincumbered with ponderous masses of supporting masonry. This form of furnace was not a creation, but the result of a gradual evolution from the old truncated pyramidal structure whose massive proportions were ignorantly supposed to be absolutely necessary, not only to support the weight of ore and fuel, but also to confine the heat in the furnace. The first deviation from the old construction consisted in a reduction of the quantity of material used by making all that part of the furnace above the tuyère arches either cylindrical or conical, and binding it with iron hoops; the lower portion remaining quite as massive as had been customary.
The next stage in the evolution made the whole furnace a frustum of a cone pierced at the base by four or more arches, that portion above the arches being hooped. The next change in construction consisted in casing the whole furnace, sustaining piers as well as the part above, in boiler iron. This construction was followed by the removal of the piers altogether, the upper conical portion of the furnace being built of cut stone hooped with iron and supported on cast-iron columns. Fig. 38 is an elevation and Fig. 39 a vertical section of one of the earlier furnaces of this construction.
There were three such furnaces built at Hyanges, department of Moselle, France, prior to the year 1849 (probably in 1845). These furnaces were forty-six feet high and sixteen feet in diameter at the "boshes" and eight feet at the top. They were built expressly for the use of coke, and, according to Overman, they "worked admirably."
The study of the construction and operation of such furnaces as these doubtless had its influence in determining the details of the Clinton Furnace of Graff, Bennett & Co., of Pittsburg, already referred to as having been the first to use "Connellsville coke" with success. This furnace, which I visited in January, 1863, was "simply a jacket" of boiler iron lined with, fire-brick. It was fifty feet high and twelve feet "bosh."
The make of iron was twenty tons in twenty-four hours. Since the date of the erection of this furnace, which at the time was the only blast-furnace in Alleghany County (in which Pittsburg is situated), Pennsylvania, there have been built within its territory twenty-four coke furnaces, which produced in 1889 "more pig iron than the whole State of Ohio; more than twice as much as Illinois; and more than one seventh of the country's total production."
The furnaces have not only increased in number, but their size and output have been very much augmented. As an illustration of this, furnace "F," of the "Edgar Thomson Steel Works," is eighty feet high, twenty-two feet diameter at the "boshes," eleven feet diameter of hearth, sixteen feet in diameter at the throat, and has a capacity of 18,000 cubic feet. This furnace produces 10,603 gross tons of iron per month (351 tons per day) on a fuel consumption of 1,756 pounds (coke) per gross ton. The pressure of blast at the tuyères is nine pounds per square inch, and its volume 25,000 cubic feet per minute, heated to 1,200° Fahrenheit.While the iron-masters west of the Alleghany Mountains were increasing the number, size, and economical working of their furnaces, the makers of "anthracite iron" in the Lehigh, Schuylkill, and Susquehanna Valleys were by no means idle; and their furnaces also increased in size and multiplied in number as the years passed. As illustrating the influence of a successful manufacture in drawing population and other industries to its immediate vicinity, no better instance could be selected than the town of Catasauqua, Pennsylvania, where was built in 1840 the furnace described in the first part of this article. Where then was but a single furnace, a small number of scattered houses, and a few score of people, we now find five furnaces, two rolling-mills, and a number of collateral industrial establishments, giving sustenance to a large and busy population. Fig. 40 is a view of the present blast-furnace plant at Catasauqua. For the purpose of showing
Fig 40.—Iron Works at Catasaqua.
at what rate the technology of the manufacture of anthracite iron has advanced during these years, we will compare the product of the furnace of 1840 with that of the furnaces on the same ground at the present time. The original furnace made in the year ending July 1. 1841, 2,460 tons; and the present plant (five furnaces) produced during the year ending July 1, 1890, 111,828 tons, or at the rate of 22,365 tons per furnace (on the supposition that they were all running), which is more than nine times the product of the furnace built in 1840 at that place.
The production of pig iron in the United States for the year ending June 30, 1890, was the largest in the history of the country, and, in fact, larger than that of any other nation in the world, being 258,216 tons in excess of the production of Great Britain in 1889. The following table exhibits the rate of increase of production of pig iron during the past twenty years:
From the above figures we see that the manufacture of pig iron in New England has been practically stationary for the past twenty years, while in the Middle States it has nearly quadrupled, in the Western States it has increased nearly five times, and in the Southern States nearly ten times in the same period.
Few persons save those connected with the manufacture of pig iron are aware of the enormous and insatiable appetite of one of the largest blast-furnaces; and the figures hitherto given fail to convey an adequate idea of the immense quantity of materials that pass through such a furnace, and it is only when the total daily amount of these materials is considered that the tremendous igneous activities constantly at work in that combination of hurricane and volcano—a modern blast-furnace of the first class— can be fully appreciated. Such a furnace will have passed through it in twenty-four hours the following materials:
which is equal to ninety-two tons per hour, or 1·53 tons per minute. From this quantity of materials there will be produced in twenty-four hours 784,000 pounds or 350 gross tons of pig iron, which is at the rate of 32,666 pounds or 14·57 tons per hour, or 544 pounds per minute.
Heating the 25,000 cubic feet of air supplied per minute to a, temperature of 1,200 Fahr., its volume would be increased to 85,000 cubic feet; and, on the supposition that the furnace is blown by seven tuyères, each seven inches in diameter, this torrid air would rush through each tuyère (under a pressure of nine pounds per square inch) at the rate of 12,143 cubic feet, and having the enormous lineal velocity of 45,417 feet per minute. This velocity is over five times that of the most violent tornadoes, and the pressure is more than twenty-five times greater. Should a blast of equal pressure and velocity come from unfathomed space and envelop this earth, it is absolutely certain that no living beings or loose materials would be left upon its rock-ribbed skeleton, which, stripped of its flesh and blood, fields and forests, lakes and oceans, would be hurled into a new orbit and made to assume revolutions and rotations whose amplitude and duration it is impossible to imagine or describe.
[To be continued.]
A contribution has been made to the speculations respecting the relative growth of the white and colored population of the United States by Quartermaster-General Meigs, who has published tables exhibiting the increase of both, by decades, since 1790. They show that the total population had increased eight-fold in 1860; while the average increase of whites by decades was 32·8 per cent, and of negroes 26·8 per cent. In 1790, there were 3,172,000 more whites than negroes; in 1880, 48,575,000; in 1890, probably 58,640,000 more; and if the present relative rates of increase are maintained, there will be, in 1990, 1,067,043,000 more. The estimate should set the apprehension of negro supremacy a considerable distance away.