US1081532A - Purifying steel. - Google Patents

Description

UNITED .PATEENT @IWIQE.

ERNEST HUMBEHI, OE SOUTH CHICAGO, ILLINOIS.

PURIFYING STEEL.

No Drawing.

To all whom it may concern Be it known that I, ERNEST I-IUMBERT, a citizen of France, residing at South Ohicago, Illinois, have invented certain new and useful Improvements in Purifying Steel, of which the following is a specification.

The principal processes of making steel are first, the converter, acid or basic, and second, the open-hearth process, acid or basic. In the acid converter process air is blown through a molten mass of pig iron so as to oxidize the silicon, carbon and manganese. In the basic converter process there is a similar oxidation of carbon, silicon, manganese and phosphorus. In both these cases the carbon is burned to carbon monoxid and carbon dioXid (CO and C0 The oXids of carbon escape as gases, but the silicon and manganese (and part of the iron) are oxidized and form the silicate or silicates of manganese and iron. A part of this silicate rises to the top of the vessel and forms the slag. When the carbon is reduced to the point desired a certain amount of silicon and manganese are added in order to deoXidize the metal according to the following reactions:

In the final combination there is always a certain amount of FeO present and the slag may be expressed by the formula In the acid open-hearth process the same reactions are used for deoXidizing the metal. In the basic open-hearth some manganese is generally added in the furnace to deoXidize the metal, part of which manganese forms MnO. Silicon is then added in the ladle to kill the metal and a silicate or silicates of iron and manganese are formed as in the converter process. This silicate or silicates constitute non-metallic impurities, and part of these are retained in suspension in the metal. Their association with the metal is a mechanical one like that of small pebbles in a mass of clay; as is shown by a microscope. These impurities do not alloy with the metal and their presence is the cause of many troubles heretofore found in finished steel, especially Bessemer rails. I propose to substantially eliminate these impurities from the steel after finishing it in the usual Specification of Letters Patent.

rateiiteanee. is, rare.

Application fi1ed. January 3, 1913. Serial No. 739,963.

way in the Bessemer or 0penhearth furnaces or indeed after finishing it in any way which results in the existence of these silicate impurities. In order to eliminate these impurities I use a special slag which I place in the finishing ladle and upon which I pour the steel from the converter or open-hearth or other vessel in which it has been formed. From this finishing ladle the metal thus purified is then poured into ingot molds or sand molds. The slag is composed of from ten to thirty (10% to 30%) per cent. silica, five to fifty (5% to 50%) per cent. calcium carbid (CaC and the balance lime. This slag has several points of advantage. It is easily fusible and remains liquid for a comparatively long time in the ladle so that it elfects a thorough purification. As'the metal is poured into the ladle the silicate of iron and manganese on coming into contact with the slag is reduced according to the following reaction:

The manganese and iron are incorporated in the metal. The oXid of carbon escapes as a gas as fast as the metal comes into contact with the slag. The reaction is instantaneous. The slag, which may be called a silico-calcium-carbid, is converted as the equation shows into the metals and the oXid of carbon and a silicate of lime. The silicate of lime is very fusible and floats on the top of the ladle with the excess (which is necessarily provided) of the silico-calciunicarbid. The maintenance of a high temperature and the liquidity of the slag is assisted by the strong chemical reaction and the evolution of heat produced by the breaking up of the calcium carbid (about 5700 calories per kilo of the carbid). This heat assists in keeping the silicate of lime very fluid and in keeping the entire mass very fluid until it is poured.

The slag should be put into the ladle in liquid form. It is made by melting a mixture of silica sand (10% to 30%) lime (70% to 90%) and adding carbon in the form of coke or anthracite or otherwise (10% to 30% of the total lime and silica). The quantity of carbon will vary according to the percentage of calcium carbid desired in the finished slag.

What I claim is- L The method of purifying steel which consists in pouring it into a finishing vessel containing a molten silico-calcium-carbid slag so as to convert the silicates of iron and manganese therein into a readily fusible silicate of lime.

2. The method of purifying steel Which consists in melting a mixture of silica and lime, adding carbon thereto pouring the steel upon the same and thereby converting the silicates of manganese and iron in the steel into a readily fusible silicate of lime.

8. The method of purifying steel which consists in melting a mixture of silica sand (10% to 30%) and lime (70% to 90%) adding carbon thereto (about 10% to 30% of the total lime and sand) and pouring the steel to be purified upon saidmelted mixture so as to convert the silicates of manganese and iron therein into a readily fusible silicate of lime.

In Witness whereof, I have hereunto signed my name in the presence of two subscribing Witnesses.

ERNEST HUMBERT.

Witnesses:

JULIUs ISRAEL, FREDERICK P. LILLEY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). G.