FIG. 3. given in the directory to the iron and steel works of the United States, by the secretary of the American Iron and Steel Association, on Dec. 31, 1885, is as follows: Charcoal, 181; coke, 202; anthracite, 208; total furnaces, 591. FIG. 4. Technical investigation of the merits of various fuels have not been as thorough as the subject demands; and comparatively little has been done in the study of anthracite coal in its adaptability as a blast-furnace fuel. Coke has received more attention, and several valuable papers have been prepared upon this topic. It is only lately, however, that the relative merits of different fuels for iron manufacture have been thoroughly investigated, the most recent experiments being those of Dr. Thoerner, of Germany, who compared large samples of a series of cokes and charcoals, and the results of his investigations are epitomized in the following comparison of coke and charcoal as blastfurnace fuels: The actual density given in the table is the density of the carbon. The loss of volume was determined by crushing and screening to a uniform size, and then subjecting the materials to equal pressures to show their relative capacities of carrying burdens in the furnace. The loss of hydrocarbons confined in cell spaces was determined by maintaining previously dried samples at a white heat in a current of hydrogen for thirty minutes. The percentages of loss in weight in carbonic acid indicate that in submitting samples for one-half hour to a current of carbonic acid the carbon in charcoal is more readily attacked than that of coke. The percentage of loss by action of a current of air upon the heated fuels for ten minutes is shown by the last column.. Items from record of working. Summary of Results of Smelting Brown Hematite Iron Ore with Various Fuels at Pine Grove Furnace. Fuel used. Charcoal, Feb ruary, 1879. 2,531 2.8 95 $8.26 22 1,896 77.8 323,845 338,187 .77 The bituminous furnaces average larger dimensions than those using anthracite, and the anthracite plants are of greater size than those which depend on charcoal, Comparing the number of blast-furnaces in the directories of July, 1882, and September, 1884, with their average nominal capacity, the following statement is presented to show how rapidly advances are being made: In statistics the net ton of 2000 pounds is used for uniformity, but in the manufacture and sale of iron the gross ton of 2240 pounds is employed, and in pig-iron an allow ance for sand of 20 to 40 pounds additional is made. Blooms Volume of Volume under pressure. Hydrocarbons. (Weight.) Carbonic acid. (Weight.) By action of air. (Weight.) The output of an old-style cold-blast charcoal furnace, 9 feet in diameter at bosh and 28 feet high, was from 4 to 6 tons of pig-iron per day, the consumption of charcoal being from 150 to 225 bushels per ton. The Mont Alto furnace, Pennsylvania, with bosh diameter of 94 feet and height of 44 feet, averaged 254 tons of cold-blast iron, on a consumption of 129 bushels of charcoal per ton of iron made. When hot-blast was employed the older furnaces of the above dimensions increased their product to from 8 to 10 tons per day; but improved appliances and management have latterly obtained 30 to 40 tons per day from similar ores in furnaces of practically the same diameter of bosh, but with larger crucibles and greater height, and the fuel consumption has fallen to 100 bushels per ton or less. doubled under more intelligent management; and furnaces 16 feet diameter and 55 feet high. which formerly made 30 tons of iron per day, now produce from 60 to 100 tons. Technical knowledge and the application of new improvements have done even more for bituminous furnaces, for in these the employment of coke with superheated blast, and the establishment of new plants, have given them advantages not possessed by others. Bituminous furnaces which ten years ago became prominent because they made 80 tons per day have now reached an output of over 200 tons per day. Raw bituminous coal has been and is used in some districts, but it is much inferior as a furnace fuel to coke, and there is also a great difference in the merit of coke from various localities for this especial purpose. The best results obtained with anthracite fuel have been where comparatively small sizes of coal are used The practice of charging very large lumps having been generally abandoned, coal of the size commercially known as "steamboat" has been substituted. A modern blast-furnace structure may be described as a wrought-iron shell or casing, resting upon a wroughtiron mantle sustained by wrought- or cast-iron columns of such height as to expose as much of the bosh as possible to the cooling action of the atmosphere. The interior shape of the furnace approximates two frusta of cones placed base to base at the bosh, the two lesser diameters fixing the size of the bottom and the stock line; the variations are mainly in cylindrical portions for the crucible or prolongation of the bosh, in greater or less slope to the bosh and inwalls, and in In larger and more modern plants of 11 feet diam- the relative sizes of the greater and lesser diameters eter at bosh and 60 feet high, using rich ores, a prod- of the two ends of the frusta. The tunnel head is uct of 70 tons per day and a fuel consumption of less fitted with cup and cone, or bell and hopper, operated than 85 bushels of charcoal per ton has been attained. by a lever, and the charging opening is covered by a Anthracite or bituminous furnaces were not operated seal plate. Gas is withdrawn just below the hopper cold-blast in America, but a comparison of results ob- and conveyed in masonry flues to the "downcomer. tained from plants twenty years ago with those of the The furnaces are of various dimensions, from the same size to-day shows that the output has practically smallest, which has a diameter at the bosh of 6 feet The shapes adopted also vary greatly, but the structure shown in Fig. 3 is typical. Figs. 5, 6, and 7 show the outlines respectively of charcoal, anthracite, and bituminous furnaces drawn to scale. Fig. 5.-A shows the shape of a Connecticut furnace producing 100 tons of car-wheel iron per week, from 45 per cent. brown hematite ores, with the consumption of about 100 bushels of charcoal, and with blast heated to about 600 degrees delivered through five tuyeres. B, a Pennsylvania furnace using 40 per cent. brown hematites, which has produced 150 tons car-wheel iron per week, with the consumption of 130 bushels of charcoal, with cold-blast; and 180 tons of forge-iron per week, with the consumption of 103 bushels of charcoal, blast heated to 800 degrees. It has four tuyeres. C, a Michigan furnace which produced an average of 345 tons Bessemer iron per week from soft red hematite ores, yielding 60 per cent. of iron, the blast being heated to 750 degrees, 90 bushels of charcoal being consumed per ton of iron. It has four tuyeres. D, an Alabama furnace which during a continuous campaign of more than seven years averaged over 17 tons of foundry iron per day, with the consumption of 115 bushels of charcoal per ton, blast heated to 750 degrees. Since remodelling to the shape shown it averages 40 tons of iron per day, consuming 100 bushels per ton, using brown hematites, yielding 45 per cent. It has seven tuyeres. E, a Missouri furnace averaging 240 tons of Bessemer iron per week, from 50 per cent. soft specular ores, consuming 98 bushels of charcoal per ton, blast temperature 650 degrees. It has five tuyeres. F, a new furnace in Texas to smelt limonite ores. G, a Michigan furnace using 60 per cent. specular ores, producing 200 tons of car-wheel iron per week, with blast at 750 degrees, and a consumption of 115 bushels of charcoal per ton. It has three tuyeres. Fig. 6.-H, a New Jersey furnace producing 70 tons per week of 15 to 20 per cent. spiegel from franklinite residuum carrying about 30 per cent. of iron, and consuming 2 tons of anthracite coal per ton of iron, with blast heated to 950 degrees. It has five tuyeres. J, a Pennsylvania furnace of moderate dimensions erected to use 40 per cent. brown hematite ores with anthracite coal or coke. It has four tuyeres. K, a Pennsylvania furnace which in a continuous campaign of nearly five years produced an average of 414 tons of foundry and mill iron from a 50 per cent. mixture of magnetic and brown hematite ores, the temperature of the blast being 870 degrees, and the consumption of fuel ( coke and anthracite) 1.3 tons. It has six tuyeres. During the campaign its best week's work was 615 tons, on a consumption of 0.95 of a ton of fuel, the blast temperature being 840 degrees and the yield of ore 53 per cent. L, a New Jersey furnace using anthracite coal mixed with to coke, and smelting 48 per cent. hara magnetic ores, which produced 235 tons per week, with blast heated to 760 degrees. It has four tuyeres. M, a Pennsylvania furnace of which no records are accessible, built for anthracite coal, has six tuyeres. N, a Pennsylvania furnace smelting New Jersey magnetites and a small percentage of hematites, the mixture yielding 53 per cent., which in a continuous campaign of three years averaged 600 tons of iron per week, with a consumption of 1.23 tons of fuel (anthracite with 12 to 18 per cent. of coke). During the campaign the best week's output was 701 tons, with a fuel consumption of 1.05 tons. It has seven tuyeres. Fig. 7.-O is one of a pair of Western Pennsylvania coke furnaces making mill iron of Lake Superior (62 per cent.) ores and mill cinder. In a continuous campaign of three years this stack produced an average of 1050 tons of iron weekly, and has made over 5400 tons per month. The blast is heated to 1200° to 1400° Fahr. Three furnaces in Illinois of same proportions and similarly equipped made the following record with all Lake Superior ores (62 per cent.) during the last half of 1885. The tons of iron made in each of the three furnaces, and the pounds of coke consumed per ton of iron made each month, are shown: P. A Virginia furnace producing from a mixture of 50 per cent. hematite ores smelted with coke about 550 tons of foundry iron per week, using blast at 1200° to 1400° Fahr. It has seven tuyeres. Q. A furnace in Central Pennsylvania which in a continuous campaign of three and a half years has produced an average of 950 tons of Bessemer iron per week from an ore mixture yielding 48.5 per cent. of iron, the consumption of coke averaging 2460 lbs. per ton of iron. It has six tuyeres and uses superheated blast. R is one of a pair of new coke furnaces constructed in Eastern Tennessee to use the fossil hematites and coke from local coal. No record has yet been made. It has eight tuyeres and uses superheated blast. Although the furnaces are numerous, their scattered locations and necessities of trade do not permit of all being active at one time. Between the years 1873 and 1885 there has been no time when over 63.7 per cent. of all the blast-furnaces in the country have been reported as in blast; and the proportion of active furnaces has been as low as 30 per cent. of the whole. The largest percentage of active furnaces returned was 82.1, as shown by the record of anthracite furnaces in April, 1880. The aggregate reported nominal capacity of all the blast-furnaces in the United States is about 9,000,000 net tons. The usual arrangement for closing the top of a blast-furnace consists of a conical bell of cast- or wrought-iron closing against a hopper of the same |