US85053A - Improvement in the manufacture of steel - Google Patents

Description

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TH OMAS S. BLAIR, OF PITTSBURG, PE NNSYLVAN IA Lam s Patent No. 85,053, dated December 22, 1868.

The Schedule referred to in these Letters Patent and making part of the-same.

To all whom it may concern Be it known that I, THOMAS S. BLAIR, of the city of Pittsburg, in the county of Allegheny, and State of Pennsylvania, have invented a new and useful Improvement in the Manufacture of Steel; and I do hereby declare the following to be a full, clear, and exact description thereof.

My invention relates to the manufacture of steel by means of the new article known as pig-bloom or pig-scrap, according to the manner in which it is produced by the process invented byEllershausen, Guzman, and Stayner, and' recently patented or about to be patented by them.

Pig-bloom or pig-scrap, so called by the inventors, consists of a conglomerate of cast-iron and an oxide or oxides, (usually the oxide of iron,) intimately mixed together, while one of the ingredients, (cast-iron or ore) is fluid, and the other is solid, so 'as to form at once in the mixing a somewhat loose-textured yet solid (as distinguished from fluid) mass.

I need not here detail the process or method of making the pig-bloom or pig-scrap, as it is particularly described in the patent before referred to; but

In order to enable others skilled in the art to use my invention, I will proceed to describe the manner in which it is to be used and operated.

' In order to the'successful conduct of the process I am about to describe, it is important that the pigbloom or pig-scrap, whichever is used, should contain such a relative proportion of cast-iron and oxide as to yield a steel of the required degree of hardness, because different qualities of cast-iron and different kinds of ore yield in'this respect different results. I therefore first make a small amount of pig-scrap, and subject it to the process hereafter described, to test the result, before preparing the pig-bloom or pig-scrapin large quantity.

Having-thus determined the proper formula for mixing the cast-iron and ore, (or oxide,) to give the desired result, I proceed to make a large -quantity of "pig-bloom or pig-scrap for use in themaking of steel by my improved process, taking care tohave the oxide and cast-iron mixed as intimately as possible.

.If"pig-scrap is used, which is in small pieces, of

' loose texture, it is careiully picked over, and those pieces which are seen to contain any raw cast-iron, being rejected, the residue, when cooled, is screened, so as to remove any loose ore from the mass. The pieces are then placed in crucibles, and treated as a substitute for blistcrcd steel or wrought-iron in the manufacture of cast-steel, the process being conducted in similar crucibles and furnace, and in the same manner as is practised in making crucible-steel, excepting that pig-scrap or pig-bloom, broken up, is used instead of blister-steel or wrought-iron.

By first making a few sample ingots of steel from the pig-scrap, which has been carefully selected and screened, as before described, the character of the resultant steel is ascertained, and any error in the proportion of ingredients -used in preparation of the pig-scrap is.corrected, in conducting the process on a larger scale, by adding charcoal in the crucible, if the test steel-ingots are found too soft, or wroughtiron if they have proved too hard.

Instead of melting the pig-scrap in crucibles, as above described, it may be melted down in an open furnace, in which case the pig-bloom, which is a loose, spongy mass, may be used, but, in this case, in order toinsure success, care must be taken, in making the pig-bloom or pig-scrap, not to have an excess of oxide, but to have such a relative proportion of ore and cast-iron as will allow of the. mass being melted; as otherwise, the ore, being in excess, would remove the carbon, and the mass would not melt by such treatment.

Another modification of my process is to take the pig-scrap or pig-bloomfl broken up into small pieces, and introduce it from time to time, in small quantities, into a bath of molten cast-iron, until the desired degree of carbouization is attained.

In this process the pieces of pig-scrap. or pi bloom, (each of which is a conglomerate of cast-iron and ore, and some parts of which are in a transition state nearly approaching to malleable iron,) serve to dilute the carbon of the cast-iron, and at the same timev the oxide of iron, which was mechanically imprisoned in the conglomerate, aids in the process of dilution.

' Thus the process of making steel ,by diluting the carbon is carried on with both malleable iron and oxide of iron at the same time; whereas, heretofore, it has beenfound impracticable to use the oxideof iron for this purpose, because, when free, it destroys the furnace. It may, however, be used-by my method, as

above described, with safety to the furnace, and greatly facilitates the reduction of the quantity of carbon.

Another advantage peculiar to this process is, that the material introduced into the cast-iron bath is of so open, porous, and spongy a texture, as to be more rapidly melted, and is, besides, in a chemical condition better adapted to produce the desired result than manufactured wrought-iron.

This method also cheapens the manufacture of steel, as the process or processes necessary to the manufacture of wiought iron are omitted, the pig-bloom or pigscrap being used without being previously converted into malleable iron.

Still another modification of my process is as follows:

Instead of introducing the raw pig-scrap or spongy pieces of pig-bloom directly into the bath of molten cast-iron, I charge it (the pieces of pig-bloomor pig-' scrap) into a separate heating-furnace, which may be situate near 'to the furnace containing the bath of molten cast-iron. It is there exposed to a high temperature, and allowedto remain at a white heat for some time, so as to sweat out the impurities, and it is then transferred, with as little loss of heat as possible, into a bath of molten cast-iron, in.wl1ich it is melted more rapidlythan manufactured wrought-iron would be, owing to the open, spongy, and loose texture of .the pig-bloom.

This method has the disadvantage of not introducing the iron-ore into the bath, as it has become chemically incorporated with the mass,.in which it was before mechanically present, by reason of the heat of the furnace,'-and hence it will be a less expeditious as well as more costly process than that before described, but it will be found better suited for making extra qualities of steel, and for utilizing materials too impure for other modes of treatment.

This last-described method obviates the necessity, hitherto experienced in the ordinary processes of steelmanufaeture, of using none but the finest quality of materials, at the highest cost, because my treatment removes a much larger amount of impurities than can be removed by the processes heretofore employed.

The furnaces and applicances-used in my process, as described-in its various modifications, may be such as are ordinarily employed in the manufacture of steel, and therefore need nofurther explanation here.

By the above-descn'bed application of pig-bloom or pig-scrap to the manufacture of steel, the operation is greatly simplified in detail, and reduced in ex- .pense.

3 Crucible-steel can be produced with great facility, the method I have described giving complete control of the process. p

In the open-furnace treatment which I have described-the product of a blast-furnace can be run, at about equal cost, into cast pig or into pig-bloom and pig-scrap, and from these two articles, thus produced directly from the blast-fiu'nace, the steel= ingot is manufactured with only one after-heating. I

In this specification the term wrought-iron is used to designate malleable iron which has been worked; whereas the pig-bloom or pig-scrap used in my process, after it has. been exposed to a high heat, becomes malleable, but is not wrought, retaining the open, spongy texture, which wrought-iron or worked iron does not possess, and which renders the use of the "pig-bloom, either before or after it is converted into malleable iron, peculiarly adapted to the manufacture of steel in the manner I have above described.

Having thus described my improvement,

What I claim as my invention, and desire to secure by Letters Patent,

1. The manufacture of cast-steel in the crucible, from pig-bloom or pig-scrap, substantially as hereinbefore described.

2. The manufacture of steel by melting.-,d0wi1, in an .open furnace, pig-bloom or pig-scrap, composed of a mixtureof cast-iron and an oxide or oxides, in

such relative proportion of metal and oxide, as to give the necessary ratio between the oxygen, carbon, and iron, to produce the desired result, substantially as hereinbefore descn'bed.

3. The, manufacture of steel fromcast-iron, by adding to the cast-iron, in a melted state,.a conglomerate