US3511490A

US3511490A - Apparatus for introducing addition agent into molten steel

Info

Publication number: US3511490A
Application number: US618389A
Authority: US
Inventors: John W Brown Jr
Original assignee: Brown Fintube Co
Current assignee: Brown Fintube Co
Priority date: 1967-02-24
Filing date: 1967-02-24
Publication date: 1970-05-12
Anticipated expiration: 1987-05-12
Also published as: GB1153117A; BE711234A; LU55548A1; DE1583962A1; FR1566407A

Description

May 12, '1970 1w; RQWN, JR v 3,511,490

l 4APPARMUS FOR INTROUClNG ADDITION AGENT INTQ MOLTEN STEEL. l Filed Feb; 24, 196? l s sneetussh'eet 1 'May 1.21970 J. W. BRoWN, JR 3,511,490 APPARATUS FOR INTRODUCING ADDITION ISLGEII'IIINTO MOLTEN STEEL Filed Feb 24, i967 3, sheetsfsheet 2 lAPPARATUS FOR INTRODUGING-ADDITION AGENT I NTQ MOLTEN STEEL.

BY Bar-vm, SWA/ N/zfvauyn fz/mural@ Unted States Patent O 3,511,490 APPARATUS FOR INTRODUCING ADDITION AGENT INTO MOLTEN STEEL John W. Brown, Jr., Lakewood, Ohio, assignor to Brown gillllitube Company, Elyria, Ohio, a corporation of Filed Feb. 24, 1967, Ser. No. 618,389 Int. Cl. C21c 5/46 U-S. Cl. 266-36 11 Claims ABSTRACT F THE DISCLOSURE An apparatus and process for making oxygen-blown steel utilizing a furnace that is moved from a position in which oxygen is blown into the steel to a position in which steel is discharged from the furnace; the furnace has afiixed to it means for discharging finely divided addition agent material (for example aluminum) into the stream of molten steel pouring from the furnace at a velocity suicient to penetrate the stream by aid of a propellant uid, even though the furnace and stream nath are moving.

This abstract is not intended to define the invention of the application or limit in any way the scope of the invention.

BACKGROUND OF INVENTION Field of invention This invention relates to apparatus for introducing a finely divided addition agent into molten steel produced by an oxygen-blown steel-making process, and more particularly to method and apparatus for introducing addition agents into molten steel while it is pouring from a converter in which the steel has been oxygen-blown,

While the invention may be employed in connection with apparatus for various types of oxygen-blown steelmaking processes, it provides particular advantages when employed in connection with the so called basic oxygen process which at present is the most widely used of the oxygen-blown steel-making processes, and for conveniencewill be described in connection with such process. In the basic oxygen process, there is usually used a refractory-lined converter furnace having a metal-containing chamber of a generally circular cross section and having a closed bottom and open top. The furnace is mounted for movement, about a fixed horizontal axis, between a generally upright position for blowing, and tilted positions in which the furnace is charged before blowing and emptied after blowing. While the furnace is in its upright blowing position, oxygen is injected through a lance to blow the molten iron in the charge until it has been converted into steel of the desired composition, primarily by elimination or reduction of carbon and other nonferrous constituents by oxidation or removal into the slag. u

After the blowing operation, the furnace is tilted to pour the molten steel into a suitable receptacle, such as a ladle from which the steel may be poured into ingot ICC of aluminum into the -molten metal in the ladle. The shot particles usually are substantially circular flat pieces about one-quarter to one-half inch in diameter and oneeighth to three-eighths inch thick.

The above descri-bed rather crude methods of introducing addition agents have involved substantial diiiculties, particularly when the addition agent is a material, such as aluminum, of a lighter density than iron. For example, it has been very diicult, if not impossible, by the above described common practices, to distribute small amounts of aluminum suiciently uniformly through the large volume of molten steel in the ladle to give the desired results substantially uniformly throughout the molten metal. Furthermore, a large part of the thrown aluminum has been wasted by dropping it onto the oor rather than in the ladle.

Even more seriously, a large portion of the metallic aluminum added to the molten steel in the ladle has been wasted by being oxidized by ambient air or by oxygen combined in the slag, rather than -by being usefully employed in carrying out an intended function such as deoxidation. This occurs primarily because pieces of aluminum thrown into and melted in the ladle tend to form a thin layer of molten metallic aluminum that floats on the molten steel with only its lower surface in contact with the uppermost portion of the steel, which is very small as compared to the total volume of steel, so that the aluminum that oats cannot permeate and deoxidize the large lbody of molten steel in the ladle as desired. The layer of molten floating aluminum contacts the air which oxidizes it, and also may contact and be oxidized by slag oating on the steel in the ladle, some of which slag is unavoidable even though precautions are taken to prevent discharge of slag into the ladle until the end of the pouring cycle.

In such prior practices, it has been the practice to add considerably more aluminum than theoretically required in order to compensate for these losses and in an attempt to overcome these problems. The excess added necessarily has been estimated since it has been impossible accurately to determine how much aluminum would be lost by dropping on the floor, and how much would be oxidized by air, and how much would be usefully used as by reacting with the oxides in the steel.

It is extremely important that the proper amount of aluminum be introduced into and properly distributed in the steel. If too much aluminum is added not only is the cost increased because of waste of expensive metal, but the steel may be overly deoxidized when it is desired to produce rimmed or even semi-killed steel.

'Residual aluminum or aluminum oxide in the steel may also exceed specifications, causing diiculties in further processing of the steel and in the physical characteristics of the finished products.

If, on the other hand, insufficient aluminum is added, the steel will not be deoxidized as desired and may have undesirable metallurgical and physical characteristics. If it is attempted to avoid the formation of the easily oxidizable lm of molten aluminum on thc molten steel in the ladle by holding relatively large bodies of aluminum below the surface of the molten steel, steel in the vicinity of the large aluminum bodies may be chilled, the aluminum may be incompletely melted, and aluminum or aluminimum oxide may be harmfully localized in the solidiied steel. Improper distribution of aluminum in steel can cause blowholes, streaks, inclusions, concentrations of aluminum or aluminum oxide, and other defects that can require steel to be downgraded or even scrapped.

U.S. Pat. 3,224,051 discloses and claims a method of propelling finely divided addition agent material into a freely falling stream of molten metal pouring from a furnace into a receptacle, and U.S. Pat. 3,260,591 claims a related method and discloses a type of gun that is particularly well adapted for such purpose. The methods and apparatuses specifically disclosed in these patents involve manual manipulation of the gun to discharge the stream of addition agent particles. These methods and apparatuses work particularly well in the manufacture of steel by the open hearth process since the freely falling stream is rather narrow, of relatively small volume in relation to the mass of steel being discharged, and moves in a substantially unchanging path, and the duration of pouring is long enough so the rate of heat generation is not sufficient to expose an employee `working with the manually operated gun to excessive heat.

However, in the basic oxygen process difficulties can arise which are solved by the present invention. The converter contains a relatively `large amount of metal, often on the order of 150 tons or more, that is poured into the ladle in a relatively short time through the large opening at the top of the furnace, in order to make possible the desired rapid operating cycle that is one of the primary advantages of the process. The resulting large quantities of heat radiated can subject an operator to discomfort or even danger if he attempts to introduce addition agent into the stream of metal as it is pouring from the converter furnace by a manually moved gun. Moreover, a gun small enough to be satisfactorily manually handled often does not have sufficient capacity to propel the desired amount of addition agent in the short pouring time. Also, during the pouring operation the furnace is initially tilted to start the pour and then tilted more greatly as the pouring proceeds until it reaches its extreme tilted position in which the furnace is emptied. The resulting changing positions of the furnace cause considerable changes in the rates of fiow, the cross sections, and the positions of the path, of the freely falling stream of molten metal during pouring; it is therefore very difficult manually to keep the stream of addition agent particles properly directed to intersect the stream of molten steel at all times during pouring, so that there can be losses of addition agent from overshooting the ladle or from causes previously discussed in connection with addition agent thrown into the ladle.

SUMMARY OF INVENTION It is an object of the invention to make possible the propelling of a finely divided addition agent to the stream of molten metal pouring from a converter furnace in which the metal has been converted into steel by an oxygen-blown process. A further object is the provision of apparatus that will eliminate the above indicated dis- -advantages in adding addition agents into molten steel.

According to the invention, the converter furnace in which molten metal is blown with oxygen to form steel in an oxygenblown steel-making process and which is movable, as by tilting, from a blowing position to pouring positions, carries propelling means, preferably of the type shown in U.S. Pat. 3,260,591. Such means is mounted in essentially fixed relation on the furnace in a position in 4which it can discharge a stream of finely divided addition agent material into the freely falling stream of molten metal pouring from the converter furnace even if the furnace is moving during the pouring. The addition agent particles are discharged at a speed, and in a pattern, such that substantially all of the particles strike the stream of molten metal and penetrate it. The method disclosed involves projecting a stream of particles from a generally fixed position relative to a converter furnace pouring molten metal in a stream into a receptacle, the particles being projected in a direction, at a speed and in a pattern such that essentially all of them are captured by and penetrate the stream of molten metal. The addition agent, such as aluminum, is thoroughly uniformly distributed in the molten metal while in particle form and after melting.

BRIEF DESCRIPTION OF DRAWINGS The above objects and features of the invention will become apparent from the following description in connection with the accompanying drawings in which:

FIG. l shows a widely used type of oxygen-blowing Converter furnace on which an addition agent-propelling gun is mounted, the furnace being shown in its upright blowing position and the steel-receiving ladle being shown ready to receive steel;

FIG. 2 is a sectional elevation, showing the furnace of FIG. 1 in its nal pouring position while addition agent is being propelled to the stream of flowing steel from the gun, the furnace and stream being shown in broken lines in an initial pouring position, and the pouring lip only of the furnace being shown in broken lines in an intermediate pouring position;

FIG. 3 is an elevation, to a scale considerably larger than that of the preceding figures, showing the propelling proportion of the gun and the control valve mounted at a distance remote from the gun;

FIG. 4 is a somewhat diagrammtic sectional elevation of the control valve showing one extreme position of the movable member of the valve relative to the port openings into the air supply conduit and to the conduits connected to the gun;

FIG. 5 is a similar cross section showing an intermediate position of the movable member relative to such ports;

FIG. 6 is a similar cross section showing another extreme position of the movable member; and

FIG. 7 is a cross section of a converter furnace 'of another widely used shape having a gun mounted thereon for use according to the present invention.

In FIG. l, the converter furnace 1, which is of conventional construction and of a widely used eccentric shape, is mounted on trunnion supports 2 in the usual manner to permit it to be tilted by conventional means not shown, about a horizontal axis to discharge the steel S produced in the converter into the ladle 3.

The furnace 1, as is conventional, has a refractory lining 4 supported by a steel Shell 5. A gun 6 has a propelling portion 7 and is lixedly mounted on the shell in a position such that, when the furnace tilts to pouring positions to pour a stream of molten metal into the ladle 3 (FIG. 2) to form a body B of liquid steel in the ladle; the gun can propel a stream of particles P into the stream of molten metal S so that essentially all particles are captured by and penetrate stream S. The particles P, which may be metallic aluminum for deoxidizing purposes, are dlscharged into the stream in a lateral direction relative to the stream.

The gun comprises (FIG. l) a supply hopper 8 that contains a weighed amount of additive agent, such as the Widely used button-shaped aluminum particles about 1A to 1/2 in diameter and 1A" to lys" thick. The hopper 8 is rigidly supported by suitable means not shown, and its upper end, not shown, is open to the atmosphere and readily available for filling and inspection. It is positioned at a location spaced from the furnace where neither the hopper nor an operator working at it is adversely affected by heat during blowing or pouring.

The propelling portion 7 is fixed to the portion 9 of the shell 5 of the furnace that is upwardly tapered when the converter is in its upright position. The propelling portion 7 is connected to the supply hopper 8 by a flexible, particle-carrying conduit 11. The propelling portion also has

metal conduits

12 and 13 connected by flexible conduits 14 `and 15 to a control valve 16 adjustable by a valve handle 17. Valve 16, to be described later, controls the rate of flow of propellant fluid through

conduits

12 and 13 and thereby controls the rate of discharge of particles from the gun. Valve 16 is connected through a conventional shut-off valve 1'8, operated by handle 19, to a hose 21 supplying a suitable source of propellant iluid under pressure, such as air at about 100 pounds per square inch gage commonly available in steel plants.

Valves

16 and 18 are supported independently of the furnace at a location where an operator at the valves is not adversely affected by heat.

The propelling portion has a particle discharge barrel 22 which, like the remainder of the propelling portion, is preferably made of heat-resistantmetal.

Propelling portion 7 (FIG. 3) comprises a body 23 having a main internal passage 24 terminating in a discharge end connected to barrel 22. At its other end the body 23 carries an internal axial nozzle 25 having a bore 26 communicating with air conduit 12 and discharging into main passage 2.4. The nozzle is axially located by being threaded in plate 27 closing the end of body 23 and llocked by setscrews 28 threaded in the body and bears against the nozzle. Propelling portion 7 also includes a u particle feed passage 31 communicating at one end with ilexible conduit 11 and at its other end with main passage 24 through opening 32 downstream from nozzle 25. To increase the velocity of air discharging from the nozzle the wall of bore 26 at the nozzle discharge end is tapered inwardly to define an orifice 33 substantially smaller in cross section than bore 26 and much smaller than the main passage 24. The air discharging from the orifice 33 travels in an expanding stream, indicated diagrammatically by broken lines A; close to the orifice 33 the stream has a relatively small cross section and travels at its highest velocity; the velocity of the stream decreases and its cross section increases at increasing distances from theV orifice until the stream cross section approaches that of the passage 24 and the velocity is substantially reduced. The air pressure in the zone surrounding the stream A therefore is substantially lower than elsewhere in passage 24; preferably the parts are so related that this pressure is less than atmospheric. Feed conduit opening 32 discharges into this zone. This promotes ow of particles from passage 31 into passage 24, and entrainment of these particles into the air stream discharging from nozzle 25 into and through passage 24 and out of barrel 22.

Another feature that increases the quantity of particles drawn into and discharged from the gun is a return conduit 34, preferably comprising

branches

34a and 34b,

opening into particle feed passage 31 at locations substantially spaced along its length, and opening into main passage 24 at a location that is downstream from orifice 33, feed passage opening 32, and the low pressure zone described above, where a substantial proportion of the kinetic energy of the air has been transferred to the particles.

The locations at which the

conduit branches

34a and 34b discharge into the particle feed passage 31 should be far enough from feed conduit opening 32 to prevent air from the branch conduits from short circuiting into passage 24 without acting on the particles in passage 31. These branch conduits include valves 35a and 35b to permit adjustment of air iiows through such conduits.

Orifice 33 and return conduit 34 in combination increase the output of particles discharged from the gun by much more than the additive effect.

Propelling portion 7 also includes auxiliary conduit 13 having a passage 36 connected to the air supply through iiexible conduit 15, disposed with its axis at a flat angle to the axis of the main passage 24 so that air is discharged downstream into passage 24 at a location downstream of land relatively close to the feed passage 32 but upstream 6 bore 42 of cylindrical or frusto-conical shape. The body includes

ports

43, 44 and 45 respectively connected through shutoff valve 18 to main air supply line 21, through

conduits

14 and 12 to nozzle 25, and through

conduits

15 and 13 to auxiliary passage 36.

The valve 16 also includes turnable movable member 46 that fits closely in bore 42 of body 41 and has a hollow interior 47 into which

ports

48 and 49 of member 46 open.

Ports

48 and 49 are located relatively to each other -and to

body ports

43, 44 and 45 to permit desired adjustment of flows of air through

ports

44 and 45. Thus, in FIG. 4 movable member 46 is positioned so all air supplied frorn port 43 can pass through port 44 and into the main passage 24 to cause maximum ow of air past the particle feed opening 32 to entrain and propel the maximum amount of particles per time unit. In FIG. 5 the member 46 is so turned that the air supply port 43 is completely open but the

ports

44 and 45 are only approximately half open, and the rate of ow of particles from the apparatus is reduced substantially below that n FIG. 4. When member 46 is turned to the position shown in FIG. 6, air supply port 43 is completely open, port 44 communicating with main passage 24 is completely closed, and port 45 communicating with auxiliary passage 36 is completely open to all of the air supplied through port 43, the flow of particles from the gun being then at =a minimum for the particular design. The particle flow can, of course, be entirely halted by closing valve 18.

The control handle 17 (FIGS. 1 and 3) of valve 16 indicates the position of the turnable member 46 by pointed arm 51 movable parallel to an indicator dial 52 fixed to the frame of the apparatus and carrying indicia 53.

The apparatus thus makes it possible readily and accurately to vary and adjust the flow of addition agent particles from the gun by a single readily-operable control valve 16, and to halt flow of particles by a valve 18, both positioned at a considerable distance from the discharge barrel of the gun at a location that is convenient, safe, and not exposed to excessive heat.

The propelling portion may be as large and heavy as required to supply the desired quantity of addition agent in the short pouring time available, since it is supported by the furnace; the other parts of the gun may also be as lar-ge and heavy as required since they are not manually supported. The propelling portion is also so designed and positioned on and in xed relation to the furnace that the stream of particles is suiciently narrow, of a suitable cross sectional pattern, and propelled from a discharge location and direction at a speed such that essentially all particles strike the stream of molten steel, are captured by it and penetrate the stream to a distance great enough to prevent oxidation of the material of the particles by the air surrounding the stream of molten steel. This occurs even though the furnace is moving through a range of tilted positions and the position of the path of vstream S of molten steel is changing relative to the furnace and the ladle.

According to the invention, after the oxygen blowing is completed with the furnace 1 in its upright position, the furnace is then tilted in the conventional manner to a position 1 (FIG. 2) at which molten steel begins to ow from the furnace and starts falling freely in a stream S' into ladle 3. At a predetermined time after iiow starts, usually determined by the time required to accumulate a desired volume of steel in the ladle, the shut-olf valve 18 is opened and valve 16 is adjusted if necessary so that a stream of particles P of addition agent is projected from the end of barrel 22 at a velocity sufficient to travel through the air and laterally impinge upon and penetrate the stream of molten metal. This continues as the furnace is further tilted through intermediate positions of which one is indicated at 1", to its final pouring position shown in full lines in FIG. 2.

The gun may be operated steadily or intermittently if desired, with constant or varying particle discharge, for the time required to discharge the proper amount of addition agent, then the valve 18 is closed and the discharge stopped. Control valve 16 may be preset for a constant particle flow and the gun operated continuously until the required amount of addition agent has been thus propelled into the stream of molten metal. Preferably, the particle discharge is halted before any large quantity of slag drains from the furnace at the end of the pour. A small amount of slag unavoidably is in the stream of molten metal, either from the steel in the furnace, or resulting from reaction of the steel with the linings of the furnace, pouring spout, or ladle; this slag, which is not concentrated in the stream S, tends to collect in a thin layer at the top of the molten metal in the ladle. Since, however, the particles P are propelled into the stream S essentially consisting of molten metal, the particles cannot contact any concentrated mass of slag and hence few if any are wasted by reaction with the slag. Furthermore, few if any of the particles are lost by dropping or falling to the fioor. For all practical purposes, therefore, all particles are captured by the flowing stream and are distributed and utilized effectively in the molten steel.

In such process, particles of aluminum, even though lower in density than steel, can be projected into and Well below the unconfined surface of the freely falling stream S at a location -where the melt is considerably hotter than it subsequently is at the ladle, and where the particles cannot be deflected or otherwise impeded in their access t0 and penetration into the metal. The complete penetration of the particles for a substantial distance into this exceptionally hot metal causes them to melt more rapidly than would otherwise be the case, while they are protected by the surrounding molten metal from the ambient air. Depending on the size of material in the particles, the melting may be largely or even completely achieved before the metal of the stream enters the mass of molten metal in the ladle.

The aluminum or other addition agent is thoroughly and uniformly distributed in the molten metal, both while in particle form and after melting or dissolution of the agent. In the preferred process described above, the particles are added throughout substantially the entire duration of the flowing stream S at a rate that supplies to each increment of metal in the stream substantially the amount of agent that is required for that increment. Thus the particles are distributed throughout the metal flowing in the stream, and the relatively small increments of molten metal containing submerged particles or droplets of addition material are dropped into and thoroughly mixed with the large body of molten metal in the ladle. While it is preferred to add addition agent to the stream at a rate commensurate with the flow of metal in the stream, in many instances satisfactory results can be obtained if the agent is added at a higher rate for a shorter time, in which case the apparatus is operated for less than substantially the entire duration of flow of the stream of metal.

According to the invention, thorough dispersion and distribution of the addition agent particles are also promoted by turbulence of the liquid molten metal which arises from several causes, such as turbulence in the stream S caused by discharge of the metal from the furnace, turbulence imparted by impingement of the particles on the metal in the stream, and considerable turbulence that occurs when the stream of metal plunges into and agitates the metal in the ladle.

For the above and other reasons, aluminum or other addition agents thus added to molten oxygen-blown steel according to the present invention can be thoroughly distributed throughout the body of molten steel in extremely finely divided condition and with a high degree of uniformity so that molecular dispersion is approached. Finely dispersed aluminum thus added reacts with iron oxides and with the combined oxygen of the steel to deoxidize the steel effectively and uniformly; if added in sufficient quantity it also promotes alloying or grain size control functions effectively with a high degree of uniformity. Furthermore, the extremely finely dispersed aluminum performs the deoxidizing, alloying or other functions before it can collect in a film on the surface of the steel where it could be Wasted by reaction with air or slag; and in its finely dispersed state it cannot chill the steel or form harmful concentrations or inclusions of metallic aluminum or aluminum oxide. Degradation or scrap loss due to improper deoxidation arising from improper amounts or poor dispersion of addition agents greatly reduced if not entirely eliminated for these reasons.

Furthermore, the invention makes possible the reproducible accurate introduction of a precisely controllable predetermined amount of addition agent into a small vollume of molten steel at an accurately controllable period in the cycle, so it is possible to obtain reproducible results from heat to heat. Consequently, a great deal of guesswork which has heretofore been necessary in steel making can be completely eliminated and the quality of steel from heat to heat can be improved and rendered more uniform.

All of these advances are made possible even under the conditions that obtain in pouring steel from movable oxygen-blowing furnaces, under which considerably more heat is present in the immediate vicinity of the pouring spout and ladle than is present in open hearth practice, and under which the furnace and the stream of molten steel may change their positions during the pouring. It is not necessary for an operator to be located at a position where he can be exposed to such heat and it is not necessary for an operator manually to move the gun to cause it to discharge particles into a moving stream of metal.

FIG. 7 illustrates utilization of the invention in Connection with another type of widely used basic oxygen furnace, one having essentially symmetrical longitudinal cross sections. In this case the propelling portion 7 of the gun is mounted on the tapered portion 55 of such a furnace 56 in a position where, when the furnace is tilted to pouring positions, the portion 7 can discharge addition agent particles into the stream of metal pouring from the furnace. The remainder of the gun, and the process, may be identical to those described above.

While the invention has been discussed in connection with the addition of aluminum to steel, it is apparent that it may be employed in the introduction of other addition agents, either alone or in admixture, into steel or other molten metals. Examples of other addition agents are lime, calcium carbide, various types of finely divided alloying metal, etc. The term finely divided as used in the claims is intended to include particles ranging in size from a small fraction of an inch to an inch or more to include the size of addition agent particles commonly used in metallurgical industries. Although the invention has been described in connection with the introduction of addition agents into pouring steel produced by a basic oxygen process in which oxygen is introduced by a lance into a charge of molten metal in an upright converter furnace, which furnace is tilted for pouring after the steel has been made, the invention may be used in connection with other types of oxygen-blowing furnaces wherein there are similar problems of properly adding addition agents under conditions where the operator would Ibe exposed to excessive heat if he Was close to the pouring ladle, and/ or where the pouring stream of metal moves substantially during the pouring, and/or where short pouring times require use of high capacity guns that are not easily manually movable.

The gun described in this application has been found preferable for carrying out the method of the invention because the quantity and velocity of discharged particles can be readily and accurately controlled. The propelling portion of this gun is disclosed and claimed in copending application Ser. No. 338,755, filed Jan. 20, 1964, now Pat. No. 3,337,138 issued Aug. 22, 1967. However, other types of guns may be used to carry out the method of the invention.

It is to be noted that modifications other than those indicated above may be made in the embodiments described as illustrative of the invention. The essential characteristics of the invention are set forth in the appended claims.

I claim:

1. Apparatus for introducing finely divided particles of addition agent into molten steel, comprising a movable furnace adapted to have oxygen blown into molten iron therein to form steel, said furnace being movable from a position in which oxygen is blown therein to a position in which molten steel pours from said furnace after Iblowing in a freely falling stream that changes position relative to the furnace until the desired amount of steel has been discharged from the furnace, and means fixed to said furnace for propelling a stream of finely divided particles of addition agent into said freely falling stream of molten steel so that the particles of said stream of particles strike such stream of molten steel so that substantially all particles of said stream of particles strike such stream of molten metal, said propelling means being adapted to propel a stream of particles that has a cross sectional pattern, and is propelled from a location and in a direction and at a speed, such that essentially all said particles strike and are captured by the molten steel in said freely falling stream of molten steel and penetrate said stream to a distance great enough to prevent oxidation of the material of the particles by the air surrounding said stream of molten steel, even though the position of the path of the stream is changing relative to the furnace.

2. The apparatus of claim 1 comprising container means for supplying particles to said propelling means, said container means being spaced from said furnace and located where it is free from adverse effects of heat, and means for supplying particles to said propelling means from said container means as said particles are discharged from said propelling means.

3. The apparatus of claim 2 in which said means for supplying particles from said container means to said propelling means is flexible conduit means.

4. The apparatus of claim 1 comprising means for controlling the flow of particles from said propelling means from a location off said furnace at which an operator is free from adverse effects of heat.

5. r['-he apparatus of claim 4 in which said control means comprises a valve means supported independently of the furnace at a location where an operator who operates the valve means is free from adverse effects of heat, and flexible conduit means connecting said valve means to said propelling means.

6. The apparatus of claim 1 in which said propelling means propels particles by propelling fluid supplied to said propelling means, and which apparatus comprises means for supplying propelling fiuid, valve means connected to said means for supplying propelling fluid, and flexible conduit means adapted to conduct propelling fluid from said valve means to said propelling means, said valve means being adapted to control the ow of propelling fluid through said flexible conduit means to said propelling means.

7. The apparatus of claim 1 in which said propelling means is adapted to receive a flow of particles and to propel them by propelling uid supplied to said propelling means, and which apparatus comprises container means from which particles are supplied to said propelling means, said container means being spaced from said furnace and located where it is free from adverse effects of heat, flexible means for conducting particles from said container means to said propelling means, means for supplying propelling fluid, valve means connected to said means for supplying propelling uid, and flexible conduit means adapted to conduct propelling fluid from said valve means to said propelling means, said valve means being adapted to control the ow of propelling fluid through said flexible conduit means to said propelling means.

8. The apparatus of claim 6 in which said propelling means has a passage extending in the direction of fiow of said particles, an opening through which particles are fed into said passage, a first propelling fluid feed opening into said passage located upstream of said particle feed opening, a second propelling feed opening into said passage located downstream of said particle feed opening, and separate conduit means connecting each of said propelling fluid feed openings to said valve means, and in lwhich apparatus said valve means is adapted to Vary the amount of propelling fiuid fed to each of said separate conduit means.

9. -The apparatus of claim 7 in which said propelling means has a passage extending in the direction of flow of said particles, an opening through 4which particles are fed into said passage, a -first propelling fluid feed opening into said passage located upstream of said particle feed opening, a second propelling feed opening into said passage located downstream of said particle feed opening, and separate conduit means connecting each of said propelling fluid feed openings to said valve means, and in which apparatus said valve means is adapted to vary the amount of propelling fluid fed to each of said separate conduit means.

10. The process of introducing finely divided particles of addition agent into molten steel produced by an oxygen blowing process in a movable furnace, comprising moving said furnace after the steel has been bloiwn to a position in which steel can pour therefrom in a freely falling stream, and discharging from propelling means mounted on said furnace a stream of solid particles of finely divided solid particles of addition agent into said stream of molten steel said stream of particles being propelled so it had a cross sectional pattern, and from a location and at a speed, such that essentially all said particles strike and are captured by the molten steel in said freely falling stream of molten steel and penetrate said stream to a distance lgreat enough to prevent oxidation of the material of the particles by the air surrounding said stream of molten steel.

11. The apparatus of claim 1 in which said propelling means is mounted at a side of the furnace so it is not directly exposed to the mouth of the furnace away from which the steel pours.

References Cited UNITED STATES PATENTS 7/1966 Brown et al 45-53 2/1968 Karsay 266-39 X U.S. Cl. X.R. 266--34