US277929A - Process of and apparatus for converting cast-iron into cast-steel - Google Patents

Description

- (No Mode1.)

E J REESE.

PROCESS OF AND APPARATUS FOR CONVERTING CAST IRON INTO CAST STEEL. No. 277,929. Patented May 22,1883.

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UNITED STATES PATENT OFFICE.

JACOB REESE, OF PITTSBURG, PENNSYLVANIA.

PROCESS OF AND APPARATUS FOR CONVERTING CAST-IRON INTO CAST-STEEL.

SPECIFICATION forming part of Letters Patent No. 277,929, dated May 2 2, 1883.

Application filed February 11, 1881. (No model.)

To all whom it may concern:

Be it known that I, JACOB REESE, of the cityof Pittsburg, in thecounty of Allegheny andSta-te of Pennsylvania, have invented a new and useful Improvement in Apparatus for and Process of Gonvertin g Cast-Iron into Gast- Steel; and I do hereby declare the following to be afull,clear, and exact description thereof. In the metallurgy of iron and steel there are two distinct processes by which cast-iron may be converted into cast-steel while the-metal is held in a continuous molten condition, each of which possesses essentially different characteristics and produces a metal of different physical properties.

The Bessemer process is conducted in a vessel in which no other fuel is used than that contained in the metal. The metalloids are eliminated by oxidation secured by oxygen from a blast of air. When the metalloids are all consumed, there being no other source from which to develop the caloric necessary to keep up-fluidity, the metal must be immediately emptied out of the vessel to prevent chilling. The physical structure of Bessemer metal so produced is cellular, porous, and spongy, owing to the gases which were occluded while the metal was blown.

The open-hearth process is conducted in a vessel in which other fuel is used than that contained in the metal. The metalloids are oxidized by oxygen supplied by metallic oxides. By the combustion of other fuel the metal may be kept in the vessel in a high condition of fluidity anda state of rest after the metalloids are all consumed. By virtue of this refining period, the metal being highly fluid, there be ing no ebuilition, the gases escape, the cells are closed and welded, and the metal, When' cast, exhibits a solid homogeneous structure peculiar to a metal which has been subject to what the workmen term a dead melt.

Ten tons of cast-iron may be converted into cast-steel by the Bessemer process in twenty minutes, while a like quantity cannot be converted by the ordinary open-hearth process in less than ten hours. The cost of converting by the Bessemer is somewhat less than by the open-hearth process; still, owing to the improved product, the open-hearth process is being generally introduced.

The object of this invention is to combine the distinctive characteristics of the Bessemer and open-hearth processes into one, with a view of securing the rapid elimination of the metalloids incident to the Bessemer process and the period of rest and resulting homogeneous physical properties of metal produced tion of high fluidity and at a state of rest until the. gases escape, whereby its porosity is reduced when cast into ingot-iron; or, if steel is desired,I may recarburizethe fluid iron and hold the steel in a condition of high fluidity and at a state of rest until the gases escape and the porosity of the metal is reduced, and then pourit into ingots or suitable molds. The period of rest will not ordinarily exceed fitteen or twenty minutes. Thus ten tons of cast-iron may by my improvement be converted into cast-steel in from thirty to forty minutes, and the resulting metal will possess all the desirable characteristics of the product of the open-hearth process.

The improved apparatus consists of a Bessemer converter having two open or hollow trunnions, with accompanying conduits, leading into the tuyere-box. The tuyere-box is divided into two distinct air-tight compartin en ts, each compartment being connected with only one of the conduits leading to the trunnions. Each compartment of the tuyere-box communicates with the interior of the converter by means of tuyeres in ordinary use. The pipes leading to the trunnions are provided with valves, by which the air-blast may be permitted to enter both trunnions and both divisions of the tuyere-box, or either of them, at the will of the metallurgist.

nected with a pipe leading to a producer of a carbureted vapor. These pipes are also provided with valves, in order to enable the metallurgist to force the vapor of carbon, hydrocarbon, or carbonic oxide into one orreither 0t thedivisions of the tuyere-box, or to exclude Each of the 'pipes leading to the trunnions is also conare reduced to the desired degree, then turn- "condition during "further treatment.

ing the converter down until the tuyeres are above the molten mass, then forcing a vapor of carbon or other combustible gas into and through one portion of the tuyeres and an equivalent amount of air through the other portion of the tuyeres, whereby combustion takes place in the converter above the molten metal, and the metal is kept in a highly fluid steel is desired the metalloids are eliminated as before described. Theconverter is then turned down, the metal then deoxygenized, recarburized, and a small portion of silicon added, the gas and air let on, and the metal kept in a state of rest and acondition of high fluidity for from fifteen to twenty minutes, whereby the metal is refined, the gases escape, and the silicon protectsthe carbon from oxidation, so that a definite percentage of carbon may be found in the resulting metal,though the metal be subjected to the refining period after recanbnrization. The metal, after the refining period of rest, is run into ingots, which will be comparativel y free from porosity an d be homogeneous.

Another feature of the improved process which forms a part of this invention is the production of different grades or qualities of steel from the same heat or blow of the converter, which I am able to effect in the following manner: In case a heat of steel is desired to be converted into different degrees of car burization for the purpose of filling dilferent orders of merchant or agricultural steels, or in the production of steel castings of different degrees of density or ductility, I blow the metal until the metalloids are eliminated, then turn the converter down and deoxygenize and recarburize the metal to the lowest degree of carbon desired. The gases are then let in,and after the period of rest is had I pour out such quantity as desired of that grade. I then recarburize the remainder to a higher degree and pour such quantity of that grade desired, and by a similar treatment produce different degrees of carbon, until the metal is all utilized. During this treatment care must be taken to keep up the temperature by a lively combustion, so that the metal may be kept in ahighly fluidstate, and sufficient silicon should be added to keep the degree or percentage of silicon in the metal continuously above .020.

. In the drawings, Figure 1 represents a converter in a blowing position, partly in section. It shows the air or gas pipes or conduits leadingfrom each trunnion into the double-chambered tuyere-box. The tuyere-box being in section,the division-plate is shown. Fig. 2 indicates the converter turned down in a refining position. It is alongitudinal section. Fig.

When

3 is plauview of the tuyere-box and connecting air or vapor pipes. Fig. 4 is a sectional view of the branch air and vapor pipes and their valves.

It will be observed that an air-blast is blown into both divisions of the tuyere-box when the converter is in a vertical position, as shown in Fig. 1, and when the converteris in the horizontal position, as shown in Fig. 2, air-blastis admitted into one division of the tuyere-box and the combustible vapor in the other, so that the air-blast first used passes through the metal, as in the ordinary Bessemer practice, while the combustion and resulting gases pass over the metal, as in the open-hearth practice.

gas-producers, such as now used in the openhearth practice, or by any other suitable means. The gas should be forced into the converter by means of a pressure-blower, in order to secure the necessary volume; but care should be taken that the pressure of the blast or the gas be not so great as to prevent a perfect combustion inside of the converter. The quantity of heat developed may be regulated by the quantity of gas and air blown in, and the quality of the flame may be regulated by supplying just sufficient air to consume the carbon to carbonic oxide, (00,) or in quantity to consume it to carbonic acid, (00

The advantages secured by the practice of this invention are, first, combining the desirable features of the Bessemer and open-hearth processes into one; secondly, by conducting the combined process in a Bessemer converter the time of treatment is not much greater than the Bessemer, and much less than by the open hearth third, the loss of metal incident to transferring Bessemer metal to an open hearth is avoided, and the metal may be poured out of the converter, avoiding the loss of metal in cleaning out the open hearth; fourth, the converter may be more readily heated and kept in a heated condition during theinterval between different heats; fifth, the metal may be keptin the converter for any length of time before being blown or after being blown and refined.

I am aware that the ,tuyere-box of a converter has heretofore been divided into separate compartments in order to reduce the vol ume and control the directionof the air-blast,

and also to introduce air and gas at separate points, and I do not claim the same; but I am not aware that provision has heretofore been made whereby the gas could be admitted to either compartment, or that the air and gas have been admitted to the converter above the molten metal therein to produce and maintain combustion, obtain a state of rest and dead melt, and permit the escape of occluded gases after decarburization and desiliconization.

I am also aware that after desiliconizing and decarburizing charges of metal the same have been subjected to an over melt" in an independent furnace in order to obtain a homogeneous mass for castings and similar purposes,

The gas may be secured by the use of the ordinary the vessel so that the tuyeres are above the molten mass, and forcing into the vessel a stream of gas or combustible vapor and an equivalent amount of air or oxygen, whereby combustion is secured above the metal, and the metal is held in a highly fluid state during the period of further treatment, substantially as and for the purpose described.

2. The method herein described of producing a metal free from blow-holes, which consists in the introduction of combustible gases and air into the converter above the contained molten metal after decarburization and desiliconization, whereby a state of rest or dead melt of the metal in the converter is obtained and the escape of occluded gases permitted, substantially as and for the purpose specified.

3. The combination, with a converter havin g its tuyere-box divided into separate com-' partments, of independent blast-pipes leading from the trunnions to the respective compartments, and branch pipes communicating with the blast-pipes, the branch pipes being provided with suitable valves, whereby air or gas may be admitted to either compartment ofthe tuyere-boX, substantially as and for the purpose specified.

In testimony whereof I have hereunto set my handthis 1st day of February, A.D. 1881.

. JACOB REESE.

Witnesses:

JOHN M. BOURKE, F. G. MCGIRR..

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