US429638A - Process of manufacturing iron and steel - Google Patents

Description

NITED STATES PA ENT Prion.

JACOB REESE, or PITTSBURG, ASSIGNOR To THE BESSEMER STEEL ooM- PANY, (LIMITEDQ on PHILADELPHIA, PENNSYLVANIA.

PROCESS OF MANUFACTURING IRON AND STEEL.

SPECIFICATION forming part of Letters Patent No. 429,638, dated June 10, 1890.

Application filed September 12, 1883. Serial ITO. 106,339. (No specimens.)

and useful Improvement in the Art of Manu-v facturing Iron and Steel; and I do hereby declare the following to be a full, clear, and

exact description thereof.

The object'of the invention is to produce dephosphorized ingot iron andsteel by the thorough decarburization and desiliconization of the crude metal and the subjecting of this refined metal to the action of a basic bath while in a basic-lined vessel and maintained at a temperature above the fusionpoint of Wrought-iron, as more fully hereinafter set forth.

In reducing my invention to practice it is absolutely necessary to secure the following conditions for dephosphorization: First, the metal must be subjected to the action of an oxygen-yielding blast or to the action of oxidizing agents, while maintained at a temperature above the fusion-point of Wrought-iron, in order that the phosphates of iron formed thereby may be able to fioat up through the bath and enter into the slag; secondly, the carbon is eliminated before the metal is treated for dephosphorization in order to prevent the formation of carbonic oxide during the after treatment, as this gas reduces the phosphate of iron and causes the phosphorus to enter again into the metal; third, the metal is desiliconized in its first treatment in order to prevent the formation of silicic acid during the second stage of the process, for if silicic acid were then formed it would attack-the phosphate and reduce'it, forming silicate of iron, and the phosphorus would again enter the metal; fourth, the metal must be treated in the presence of a highly basic slag, in order that any silicic acid which has been formed may be provided with a base which will be capable of holding it as silicates, and thereby prevent its decomposition of the phosphate, as above stated; or, in other words, the metal must be subjected to oxida tion in the absence of carbonic oxide and of free silicic acid, and in'the presence of basic .of the lime upon it.

conizing previous to-after treatment-are most economically obtained by the use of an acid-lined Bessemer converter, but may also be had by the use of an acid-lined open hearth. The fourth condition necessitates the removal of the acid lining, its replacement with a hard durable lime lining, and the use of basic additions.

In carrying the invention into practice it is proposed to decarburize and desiliconize molten metal by subjecting it to the action of anair-blast or by exposure to an oxidizing flame or gas in the usual manner. This decarburized and desiliconized metal is then transferred, minus its acid slag, into a limelined open-hearth or Bessemer converter, and subjected to oxidation, while covered with a basic calcareous slag, until the phosphorus is eliminated from the metal, and the phosphate so formed enter into the slag. The resulting molten dephosphorized metal is then treated with deoxygenating, or deoxygenating and recarburizing, agents to produce the grade of ingot iron or ingot steel that may be desired.

In the operation referred to the phosphorus is not removed from the metal by any action It is present in the metal either as a phosphideor simply as phosphorus, more probably in the former state. In either case a phosphate of iron results from the exposure of the metal to oxidation. In the first the phosphide would be oxidized to a phosphate. In the second the phosphorus would be oxidized to phosphoric acid, which would instantly combine with oxide of iron, 9 5

silicic acid are then absent from the bath. The lime has nothing to do with this action of the blast. Its functions are to supply an excess of base for any silicic acid present to combine with, so that it will not be free to decompose what phosphates are formed, and to act as a'slag to retain the phosphates after the phosphorus has been eliminated from the metal. The basic bath may contain enough oxide of iron to flux the lime sufficiently to cause the latter to form a fluid or semi-fluid slag. The amount will vary, of course, with the varying infusibility of the lime employed.

The entire process may, if desired, be conducted in a basic-lined converter, in which case the metal is run into it. Lime additions of from twenty to thirty per cent. of the weight of the metal are then added, and the bath is then subjected to the action of an airblast until decarburization, desiliconization, and dephosphorization have been effected; or the entire process can be conducted in like manner in a basic-lined open hearth, and in the presence of a highly-basic slag, by subjecting the metal to the action of an oxidizing flame or agent, and maintaining it at a temperature above the fusion point of wrought-iron until decarburization, desiliconization, and (lephosphorization have been eltected.

Pending applications filed February 1, 1882, Serial No. 51,606; February 3, 1882, Serial No. 51,788; August 31, 1883, Serial No. 105,256; September 12, 1883, Serial No. 106,340, and September 15, 1888, Serial No. 106,548, describe a somewhat similar process; but in neither of them is the metal treated in a basic bath composed of oxide of iron and calcareous matter.

I do not now claim hard, durable, indurated, refractory lime linings or replacing acid linin gs therewith; nor do I now claim the formation of a basic slag by the use of lime linings and lime additions; nor dephosphorizing in the absence of free silicic acid; nor dephosphorizing in the absence of carbonic oxide; nor dephosphorizing by means of an overblow.

VVhat I claim, and desire to secure by Let ters Patent, is-

1. The improvement in the art of manufacturing ingot iron and steel, which consists in first decarburizing and desiliconizing the metal while in a molten condition by subjecting it to the action of an oxidizing agent and afterward treating the decarburized metal, while free from contact with silicious substances, with a calcareous reagent and oxide of iron, and maintaining the bath at a temperature above the fusion-point of wroughtiron until dephosphorizat-ion is effected.

2. The improvement in the art of manu facturing ingot iron and steel, which consists in first decarburizing the metal while in a molten condition by subjecting it to the action of an oxidizing agent, and then treating the decarburized metal with a calcareous agent and oxide of iron while maintained at a temperature above the fusion-point of wroughtiron.

JACOB REESE. lVitnesses:

C. 0. LEE, WALTER REESE.