US1925247A

US1925247A - Purifying ferrous metals

Info

Publication number: US1925247A
Application number: US556613A
Authority: US
Inventors: Charles T Hennig
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-08-16
Filing date: 1931-08-12
Publication date: 1933-09-05
Anticipated expiration: 1950-09-05

Description

Patented Sept. 5, 1933 e I v than? PURIFYING FERROUS METALS Charles T. Hennig, Cleveland, Ohio N Drawing. Original application August 16,

Serial No. 386,490. Divided and this appiication August 12, 1931. Serial No. 556,613

3 Claims.

This invention relates to the manufacture of steel by the acid or basic Bessemer process, and, as to the basic open hearth process, this application is a division of my prior application Serial No. 386,490, filed August 16, 1929, for Patent No. 1,826,881, October 13, 1931.

It is one of the objects of the invention to produce a steel which will have an exceptionally good surface and also be uniform and without inclulO sions or hard spots. I have found that hard spots in steel are usually manganese and iron silicates and oxides and that the elimination of these segregations of manganese and iron silicates and oxides results in the steel having clean surfaces and being more ductile and better adapted for forging and deep-drawing and for the manufacture of wire and other products. In the Bessemer process, it is common practice, in steel plants, to utilize the hot iron from the blast furnace and the present invention relates to the treatment of the metal in the transfer ladle on the way to the Bessemer converter so as to eliminate, to a large extent, the inclusions and dissolved oxides and silicates prior to the blow. The treatment consists preferably in the addition to the metal in the ladle of a purifier which consists essentially of commercial soda ash in combination with certain other materials to control and regulate the action of the soda ash so as to obtain substantially uniform and dependable results.

In my Patent No. 1,826,881, I have described and claimed a method of purifying the metal, which consists in treating it in the ladle, after the blow, with said purifier, but it frequently happens that the metal as it comes from the blast furnace, cupola or mixer is not in proper condition because of an excessive amount of oxides and other impurities which will not be eliminated by the blow because the latter is, itself, a process of oxidation. It is, therefore, one of the objects of this invention to eliminate these oxides and impurities prior to the blow so that the metal, after the blow, will contain only the normal amount of oxides that are formed as a result of the blow.

The purifier may vary as to its composition, but I have found that the following composition is entirely satisfactory:

Commercial soda ash (NazCOa) Calcium oxide (CaO) as limestone Manganese dioxide (M1102) Chlorine, as calcium chloride (CaClz) or sodium chloride (NaCl) 80% to 90% 2% to 6% to 1% The balance of the material consists of a binder in the form of silica, magnesia, iron and alumina. The materials, substantially in the proportions specified, are made up in the form of briquettes and the binder that is used in these briquettes is preferably glucose or molasses refuse, which is mixed with the other materials of the briquettes in a heated condition, the mixture being then run through a machine in which it is pressed into briquette form. These briquettes are preferably of a size that would weigh about three ounces each. Instead of making briquettes as described, the materials (without the binder) may be melted at a temperature over 2000 F. and then run out onto iron plates and broken up into pieces of from inch to 3 or 4 inches in size. It is also possible, in making the briquettes, to mix the materials with a small amount of Water which will, through its action on the soda ash, produce heat and harden the mixture when it is pressed into briquettes.

The purifier, made into lump form by any of the methods above described, is put into the transfer ladle in which the hot iron is transferred from the blastfurnace or mixer to the open hearth or Bessemer converter, and this may be done either before or during the pouring of the metal into the transfer ladle.

The action of the purifier results in a violent boiling of the metal, the soda ash being broken up and the carbon dioxide and other gases that are released causing this and also causing the purifier to be difiused throughout the metal. The soda ash takes the oxygen from the dissolved iron oxides and the manganese oxide and also reacts with the iron manganese silicates forming sodium silicate and metallic iron and manganese. The sodium silicate rises to the surface of the metal and enters the slag therein. When the action of the purifier has been com- I pleted, the metal is thoroughly degasified and cleansed of the oxide and other impurities which it originally contained. The resultant slag containing the impurities is liquid and very quiet and acts as a protector for the surface of the 9 metal.

The amount of the purifier to be used will vary from one-half pound to four or more pounds per ton of metal treated, depending upon the conditions and appearance of the metal, it being understood that those skilled in the art are able to determine the condition of the metal from its appearance and hence, will be able to prescribe the amount of purifier that .is to be used in any case.

After the metal has been treated in the transfer ladle, as above described, it may be poured into the converter and the procedure set forth in my Patent No. 1,826,881 may be followed to remove oxides formed during the blow.

If the metal is poured into a converter, to make Bessemer steel, the procedure set forth in my application Serial No. 386,490 may be followed.

Having thus described my invention, I claim:

1. The hereindescribed method of purifying steel in the course of its manufacture by the Bessemer process which consists in treating the molten cast iron while in the transfer ladle and prior to its introduction into the Bessemer converter with a deoxidizing material in the form of an intimate mixture comprising commercial soda ash and manganese dioxide, and wherein the soda ash is over three-fourths of the mixture and the manganese dioxide is an effective amount up to five per cent, for controlling the action of the soda ash as and for the purpose described.

2. The hereindescribed method of purifying steel in the course of its manufacture by the Bessemer process which consists in treating the molten cast iron while in the transfer ladle and prior to its introduction into the Bessemer converter with a deoxidizing material in the form of an intimate mixture comprising commercial soda ash, a calcium compound and manganese dioxide and wherein the soda ash is over threefourths of the mixture, the calcium compound has a calcium oxide content that is an effective amount up to ten per cent, to substantially raise the melting point of the soda ash, and the manganese dioxide is an effective amount, up to five per cent, for controlling the action of the soda ash as and for the purpose described.

3. The hereindescribed method of purifying steel in the course of its manufacture by the Bessemer process which consists in treating the molten cast iron while in the transfer ladle and prior to verter with lumps of a deoxidizing material in its introduction into the Bessemer con- V the form of an intimate mixture comprising com mercial soda ash, a calcium compound and manganese dioxide and wherein the soda ash is over three-fourths of the mixture, the calcium compound has a calcium oxide content that is an effective amount up to ten per cent, to substantially raise the melting point of the soda ash, and the manganese dioxide is an effective amount up to five per cent, for controlling the action of the J soda ash as and for the purpose described.

CHARLES T. HENNIG.