The Birmingham age-herald., 1914-11-08

nInH2f0nR- but exact weights must be determined by chemical analysis and careful cal eulallons. Storage bins of these ma terlals are filed by bottom dumping railroad cars. The double, inclined, self dumping skip hoist with one skip olscharging while another loads fills the top hopper with coke, ore and Aux; chen an iron cone or "belr' operated from the ground lets the charge fall into the main hopper and a second bell distributes it in an annular stream on top or the previously charged materials Tn the furnace. More material is sup piled when necessary to keep the charge within a few feet of the lower bell. This double bell and hopper con- struetion on modern furnaces closes the furnace to the atmosphere as 1t is charged so that the picturesque but costly long flame from the top as burn Ing gases rise from single bell and hopper furnace is not found in modern plants. At the top of the hearth are S-16 pipes, Al inches internal diameter called tuyeres through which the hot blast under 10-15 pounds per square inch pressure is forced to the center of the furnace by blowing engines or centrifugal blowers. From 4-5 tons of air are supplied per ton of iron pro- duced. The inner ends of the tuyeres are kept from melting by cold jacket water constantly running through hol- low bronze collars
 Hot Blast Stoves
 Hot blast stoves are tanks no feet high and 22 feet in diameter, contain ing two or more chambers. Each fur mace requires 4-5 stoves. One chamber is open and the other filled with a checker work of refractory brick. Gases and air enter at the bottom, burn and ri mn ha HiIA n combustion chamber and pass down through the devious paths to the an- nular space around the outer chamber then out to a stack. When the bricks have absorbed most of the heat possi- ble from the gases, the stove Is ready to heat the air blast to S00-1200 de- grees Fahrenhit. Only one-third of the gasses produced in the blast furnace are required by the stoves, so that the rest can be burned under steam boil CTS producing S5-95 British thermal units per cubic foot
 Slag and iron separate by gravity. The creamy and smooth flowing slag is drawn off four or five times between each iron tap" of six hours through the water-cooled "cinder notch" 30-4o inches< below the tuyeres on the side of the furnace. An inclined iron run ner" 15-30 feet long directs the slag to a large iron ladle-car, standard gage, and hauled by locomotive to the slag dump. The heat lost when the slag cools Is 1600-2000 British themal units per pound.
 In front and at the bottom of the hearth, a large hole in the brick work filled by several balls of clay after the last flushing" Is punctured by a heavy steel pointed bar operated by several men, From 100-150 tons of molten pig iron flows out of this iron notch" into l. its runner, About 30 tons of slag car ried along with 1t is deflected into an other runner about 10 feet from the l furnace by a horizontal plate called a "skimmer'' as the heavier iron flows under it and into ladies and is carried 1 to the mixer at the steel plant or | to a pig casting machine It can be l run into a sand casting bed; or 1T pro tected from sand Is desired as for pigs used in the open hearth steel pro cess, into permanent iron molds. 5t | The weight of slag varying from one half to two times the weight of iron pro- duced can be calculated from the lime used If 15O0 pounds of limestone is used per ton of iron and contains bO per cent lime there is 750 pounds per ton. If the slag analysis shows 40 per cent lime then it's weight Is 750 divided by 40, equal ing 1875 pounds per ton or iron Tor all the lime must appear in the slag. stable slag results from the silica in the iron combining with the lime or magnesia of the converter lining during the blow, and the phosphorous also goes into the slag as calcium or magnesium phosphate.
 Typical Analysis of Slag
 Slag is a physical mixture like an all lcy of double silicates of lime and alum ina, silicate of magnesia and other bases and oxides of iron and manganese.
 The following is a typical analysis of basic slag as arrived at by the Ten nessee Coal, Iron and fsailroad com pany:
 Silica ......................... 33.045 Lime .............-............ loS4l Iron and alumina ................... l5.b4o Magnesia ......................... .745 Sulphur ........................- ll1
 Having described the production and composition of sag. we now come to its various commercial forms and uses.
 It's applications to building construc- tions are many following from the gen. eral supplanting of iron, wood and stone by concrete.
 Descriptions are given under headings and in the order of the quantities of slag used for these purposes at pres ent.
 Railroad Ballast
 When free use of slag was encouraged, the TdllrOddS dNdHeu tHeIHSeiNtS Ol tflls excellent material for track ballast, fills and concrete work. Now they continue its use, recognizing its excellent quail ities and low cost compared to gravel and crushed granite.
 It forms a compact and dustless road bed. The bulk of the slag output of shovel run" sizes are used by rail- roads.
 Road Metal
 Modern roadmaking became possible by the invention in 1858 of the rock crusher by Eli Whitney Blake Q795-1SS6), nephew of the inventor of the cotton gin. and by the first use of the road roller at Philadelphia in 1868, patented in France 10 years before.
 or the 2,20OO0O miles of roads in the United States earth roads comprise D. OOd,00O.
 Alabama has 49,6s7 miles of roads of which 5491, or 9.35 per cent, are i'm proved" This means proper drainage grades reduced below per cent, good alignment and suitable foundation and surface materials added. The appropri- ations in 1913 were s1,5S4424 for roads and sS33,176 for bridges so the total high way expenditures was nearly $2000, 4H. In New York $20,000,000 were voted to be used for state roads. The average cost of the Alabama roads per mile was $4O00 for macadam, s2580 for gravel, $15O0 for sand-clay and $12O0 for top soil
 Foundations have averaged six inches horse-drawn vehicles made possible by improved roads and still heavier loads carried by motor trucks will require of nj inp nr iv,c