US349744A

US349744A - Process of dephosphorizing iron by means of oxides of iron

Info

Publication number: US349744A
Authority: US
Publication date: 1886-09-28
Anticipated expiration: 1903-09-28

Description

UNITED STATES PATENT OFricE.

, JACOB REESE, OF PITTSBURG, PENNSYLVANIA.

PROCESS OF DEPHOSPHORIZING IRON BY MEANS OF OXIDES OF IRON.

SPECIFICATION forming part of Letters Patent No. 349,744, dated September 28, 1886.

I Application filed August 23, 1883. Serial No.. 101,532. (No s1 ecimens.)

To all whom it may concern.-

Be it known that I, JACOB REESE, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Process of Dephosphorizing Iron by Means of Oxides of Iron; and I do hereby declare the fol lowing to be a full, clear, and exact description thereof.

The improvement consists in the formation of a non-calcareous basic slag in Bessemer converters and similar refining-chambers, and in effecting the removal of the phosphorus from the metal into the slag.

A highly refractory calcareous slag formed by the use of lime linings and lime additions is employed in the basic process as at present practiced. The weight of the lime additions runs from twenty to thirty per cent. of the weight of the metal, and the large quantity of refractory slag formed thereby tends to and in some instances does chill the metal. The slag is also apt to form troublesome accretions to the lining of the converter. In my present invention I propose to overcome these defects by producing and using an oxide-of-iron basic slag which will be more fusible, more liquid, can be used in less quantity, and can be run quickly in a highly fluid state into the converter.

In the practice of the basic process it has been found that the elective affinity of the phosphorus during oxidation is for oxide of iron, and after oxidation it is initially held as a phosphate of iron in the calcareous slag. If the slag is of ahighly calcareous basic nature, the phosphate of iron may be decomposed and a phosphate of lime formed. In the practice of my invention I therefore propose to make my non-calcareous basic slag by the use of oxide-of-iron linings and oxide-of-iron additions to the converter. The quantity of the oxide additions will be less than in the use ofa calcareous'slag, first, because the slag will be more fusible and be thoroughly admixed with and wash the metal; second, on account of being its first elective affinity the oxide-ofiron slag will take up a greater percentage of phosphorus before saturation is effected. The use of the oxide-of-iron slag may also prove more advantageoua because, being in a very highly fluid condition, it cannot entangle and hold in mechanical suspension aslarge an amount of particles of metal as is held at the close of the blow by the calcareous slag. Further, as the slag will be highly fluid, less of it will be mechanically held in the metal at the end of the blow.

In the practice of my improvement Ifirst form an oxide-of-iron lining in the converter, which may be done by melting oxide of iron as free as practical from silica and phosphorus in a suitable cupola or furnace, and then' casting the fluid oxide into the converter and around a suitable core, thus forming a lining consisting of a single mass of hard, close, and dense oxide of iron. The bottom lining is then formed in a similar manner, the cores are withdrawn and the bottom adjusted, and the converter got ready for operating. A charge of metal is then run into the converter and an addition of from ten to twenty per cent. of melted iron ore (compared with the weight of the metal) is run into the converter. The airblast is then turned on and the blow is continued in the usual manner until the phosphorus is removed from the metal into the slag. In conducting this operation the phosphorus is eliminated under the following conditions: If it abide as phosphorus in the metal, it would become oxidized to phosphoric acid, which would pass up and unite with oxide of .iron, (its first elective affinity,) and thus form of iron chemically combinedthen both are oxidized together, forming the phosphate of iron, which is taken up and retained by the slag. The amount of oxide-of-i.ron additions necessary will vary in proportion to the varying amounts of silicon and phosphorus present in the metal treated by the different blows, as is now the ease with lime additions in the .use of the calcareous basic process, but will run at least one-third less in weight than the additions used in the latter process.

As the linings used in carrying out my improvement are not of a highly refractory na ture, it is necessary to conduct the process in an air or water jacketed converter to maintain the lining below its point of fusionsueh,- for instance, as shown and described by me in an application filed June 4,1880, Serial No. 35,514, for converting crude cast-iron into cast-steel.

I am aware of English patent of Talabot, No. 370 of 1857, in which the metal is subjected to the action of air-blasts while in a chalk or chalk and oXide-of-iron lined vessel but in this patent the metal is not treated in the presence of oxide-o'f-iron additions, and it is not admissible to suppose that suflicient oxide of iron would be formed by the oxidation of the metal, as it will require from. ten. to twenty per cent. of oXide-of-iron additions, and to produce such a large amount by the oxidation of the metal would be destructiye to the economy of the process.

I am also aware of Englishpatents of Henderson, 1,051 of1870 and 2, 9:40 of1870, in which oxide of iron .and finer-spar are used as a lining and slag. A lining of this character is not practical, as fluorspar is one of themost powerful fluxes known to metallurgists, and would have a tendency to flux the oXi(le-of-iron lining down at a temperature certainly below 2,000 Fahrenheit, while a temperature of 4,500 is an essential condition of my process, and the presence of fluorine or fluorine spar would be destructive to my lining and the process.

blowing the metal in the absence of carbon and in the presence of a non-calcareous basic slag until the phosphorus is eliminated from the metal by oxidation and held in the slag as a phosphate, substantially as set forth.

2. The step of forming a non -ealeareous basic slag, which consists in blowing molten metal with an air-blast while held in an oxide U of-iron-lined vessel, and in the presence of from ten to twenty per cent. of oxide of-iron additions, until a fluid non-calcareous basic slag is formed, substantially as set forth.

JACOB REESE. \Vitnesses:

WVALTIJR Rnnsn, O. 0. LEE.