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which the ore can readily be taken out in the same manner. The mine being thus opened or "stripped,” tracks are laid in all directions upon the face of the deposit. These excavations are usually worked in terraces. The ore, being lifted
esota, the Menominee in Michigan and Wisconsin, the Marquette in Northern Michigan, the Gogebic in Michigan and Wisconsin, and the Vermillion in Minnesota.
The iron ore in the United States may be considered in four general commercial classes—red and brown hematite, magnetite, and carbonate. Of these four, the red hematite is the most popular, because of its richness in iron and its freedom from foreign and non-metallic material. These classes are subdivided under various local or trade names.
Three general methods are employed in the United States in mining the oresurface, drift, and underground. In locations where the ore is very hard or lies at a depth of sixty feet or more from the surface, the latter method is employed. Shafts or tunnels are driven to the ore beds, which are then worked in a similar manner to coal. In those districts where the ore is found in a loose condition just under the surface, surface mining is almost altogether followed.
Surface Mining for Iron Ore Where surface mining is employed, the ore must be easy to get at. The top soil is first removed by steam shovels, after
An Old-Time Blast Furnace. One of the first furnaces in this country, still standing of
near Lakeville, Conn.
A MODERN ORE DOCK.
by the numerous steam shovels, is placed directly on specially constructed cars, in which it is hauled to the docks. In this manner immense quantities of ore are obtained at a cost not exceeding forty cents a ton, while the drift and underground require an expenditure of seventy to eighty cents a ton.
The ore ranges of Lake Superior have added more to the economical advancement of American iron than any other single thing. They have given birth to the thousands of miles of railroads that are scattered throughout that district and that devote their entire traffic to the transportation of iron ore. They have added to the Great Lake shipments millions and millions of tons; given employment to thousands of boat builders and crews; forced the Government to make improvements throughout their course; and caused the growth of towns all through the mining districts and the building of the largest docks in all the world.
Mammoth Labor-Saving Docks With more than typical American enterprise these docks are built with the latest labor-saving devices. The specially constructed cars are run out upon them, and their hopper floors dropped, permitting the ore to fall into numerous bins below. Underneath and on both sides are long rows of chutes through which the ore passes into the holes of the large ore-carriers. These boats are invariably filled to their very hatches. Over twentyone million tons of ore were transferred through these docks last year. The magnitude of these structures that extend like an immense peninsula into Lake Superior, can therefore readily be imagined.
A large fleet of steamers are constantly plving between their Western docks and the Eastern unloading harbors all during the summer and fall months when the northern Lakes are open for navigation. In winter all shipments are suspended; consequently a large accumulation of ore must always be stored in the East, either at the docks or at the furnaces. Some vessels have a tonnage of six thousand tons, and so perfect are the loading facilities that it seldom requires over five hours to load them.
After a trip through Lakes Superior,
MOUNTAINS OF IRON ORE IN STOCK AT THE FURNACES, WAITING TO BE CONVERTED INTO PIG IRON. Michigan, Huron, and Erie, the immense American engineer been demonstrated, ore vessels, whether large, ordinary for on every side are the huge yet rapid steamers or still larger and strange machines that transfer the ore from the wlialebacks, arrive at one of the many dark depths of the ship's hold to the huge unloading docks of Cleveland, Conneaut, pile on the docks. These monsters of or Ashtabula.
steam or electricity have grown to such Here, more than anywhere in the perfection and magnitude that the ore world, have the ingenuity and skill of the boats are rarely held longer than ten
hours to have their contents transferred to the storage piles. The boats usually return west with coal as ballast.
As wanted, the ore is loaded into cars, either directly from the steamers or from the stock piles, and transferred by rail to the furnaces. The great Pittsburg district is the destination of the greater portion of this ore. So thoroughly mechanical and free from labor have been these numerous operations of mining, loading, transporting, and delivering the ore in the Pittsburg district, that an expenditure of only two dollars and fifty cents a ton has been incurred.
The greatest advancement which American iron manufacture has made in recent years is in the handling of the raw and finished materials at the fur
naces. This is due largely to the great THE CASTING MACHINE, The modern method of solidifying the iron. increase of tonnage during the past ten years. Over ninety million tons of raw coke and limestone are run upon a trestle and seventeen million tons of finished under whichare arranged the bins. By this material were handled last year at the method they can deliver their contents four hundred and twenty-eight furnaces directly into the bins without any addiscattered throughout the United States. tional handling, the cars being provided The raw material alone represents an ex with bottom gates. Many of the largest penditure of over one hundred and plants have sufficient bin space to permit thirty million dollars.
a large quantity of ore to be similarly
stocked, thus reducing the cost and holdMighty and Almost Human
ing the large stock supply for emergency Machines
and winter usage. In contrast with the old-fashioned The modern blast furnace is a gigantic method of hand labor, the mighty and all structure, oval in shape and towering
but human machines are to-day employed. some ninety to one hundred feet in From the moment the long trains of ore, height. It consists of an outer coating coke, and limestone arrive, through the of steel plates, with an inner lining of period of unloading, charging, melting, fire brick. Accompanying these stacks casting, and loading the finished iron, are invariably two or more cylindrical man never once enters into the operation. steel structures known as stoves. They
The ore cars are lifted upside down and are usually smaller in diameter but as their contents dumped into large iron high as the stacks themselves. Their buckets, which automatically carry them particular work consists in utilizing the either to the long row of bins or to the waste gases to heat the blast for the large stock piles. The cars containing the furnace.