Ingot
A mass of metal which has been cast in a suitable mould for convenience in subsequent working by the various processes of rolling, hammering, casting, etc.; some consideration is also given to the best forms for shipping, etc. Copper is made into bricks and pigs; tin into blocks; zinc into cakes. These are all run into metal moulds which give them their respective shapes. The blocks of commercial gold and silver are called bars. Cast iron is run direct from the smelting-furnace into moulds formed in an adjacent sand-bed, the product being pigs.
Running or "teeming" steel ingots, produced by melting blister-steel in crucibles, or from steel prepared by melting puddled steel with spiegeleisen or black oxide of manganese, if the ingots are small, is usually done by hand, by simply emptying the contents of the crucible direct into the cast-iron ingot-mould. If one crucible is insufficient to fill the mould the pots are doubled, that is, two crucibles are emptied into one larger, so that the one operation suffices; but in larger-sized ingots it is often necessary to employ two streams in order to secure an uninterrupted flow of steel into the mould. Extra-large ingots, made from this class of steel, are often run from one ladle by simply melting all the steel in the several crucibles and emptying their contents therein. The ladle employed for this purpose is clay or brick lined, and provided with a nozzle at the bottom, in which a gannister plug or stopper is fitted. This stopper is connected with a vertical rod attached to the arm for raising and lowering the stopper; the rod itself being inside the ladle, is necessarily coated with about 1 1/2 inches of the gannister composition also. By this means a continuous stream of molten steel is delivered, clear of the mould sides, and without fear of intermission until the space is filled.
This ladle, as just described, is the one used for running the steel ingots produced by the Bessemer process, only in this instance it is suspended on an arm which extends from the head of the hydraulic crane in the centre of the casting-pit. The ingot-moulds, being arranged in order around the outer diameter of this pit, are filled in succession by simply bringing the ladle directly over and allowing them to fill by withdrawing the plug at the bottom. Sometimes these ingots are cast in groups arranged round a central one that is placed higher than the rest, and connected with the latter by means of a system of fire-clay runners which radiate from the central ingot, at the bottom, to as many as may be grouped around it. The steel in this case enters the central ingot at the top, and gradually fills all the rest from the bottom.
Very large ingots, which are sometimes over 20 feet long and may weigh from 14 tons up, are preferably cast from the bottom, and suitable provision is made by forming a fountain-runner within a core made from a gannister and fire-clay mixture, which is set in the prepared bottom of the mould. One end of this runner extends past the ingot-casing, and is connected with a vertical cast-iron and gannister-lined runner-box, which, resting thereon, is made to project somewhat above the top of the ingot-casing. This casing usually consists of two wrought or cast iron half-circles, protected by a fire-brick lining coated with some refractory composition. These halves, when duly prepared, are bolted together, with a loam packing between the joining flanges, and then brought into a vertical position for setting down, on a soft loam packing also, upon the lower portion of mould already in the pit. Ingots of even larger dimensions are often made with a central core. Owing to the intense heat to which these cores are subjected, the ordinary preparations are simply valueless, as they are sure to be melted. To overcome this difficulty, the cores are made in one or more lengths, as desired, by ramming composition sand of a very refractory nature around an ordinary cage core-iron, the cast rings of which are not permitted to approach the surface by at least two inches. By this means a core is obtained containing the smallest amount of iron possible in its construction; in fact it is, literally, a sand-core almost free from substances which would be likely to melt. All such ingots are invariably run at the bottom. See PRESSING FLUID STEEL; REEKING INGOT-MOULDS; RUNNING STEEL INGOTS.