US2546337A - Metallurgical apparatus - Google Patents

Description

March 27, 1951 G|BSON 2,546,337

METALLURGICAL APPARATUS Original Filed Aug. 28, 1944 4 Sheets-Sheet l 4 Sheets-Sheet 2 Original Filed Aug. 28, 1944 Ma d m4.

March 27, 1951 R; M. GIBSON METALLURGICAL APPARATUS 4 Sheets-Sheet 5 Original Filed Aug. 28, 1944 March 27, 1951 GIBSON 2,546,337

METALLURGICAL APPARATUS Original Filed Aug. 28, 1944 4 Sheets-Sheet 4 4 ,Mi- ENVEVNTO'R {7 aZii myl/ Patented Mar. 27, 1951 METALLURGICAL APPARATUS Robert M. Gibson, Pittsburgh, Pa.

Original application August 28, 1944, Serial No. 551,492. Divided and this application February 12, 1948, Serial No. 7,777

Claims.

My invention relates to metallurgical apparatus, particularly to apparatus for refining metal in molten state, such as apparatus for practicing the Bessemer process.

In Letters Patent oi the United States Nos. 2,291,221 and 2,291,222, granted to me on July 28, 1942, I illustrate and describe certain improvements in apparatus for producing steel by the Bessemer process. In the production of steel by such process a bath of molten iron (typically pigiron) is blown through with air. By the inblown air the silicon, the manganese, and the carbon present in the iron are burned out, with a generation of heat sufiicient to maintain the metal in molten state. Afterward manganese and carbon in'measured quantities and to the required degree are restored to the metal, and other and various desired components of the ultimate steel as well. The converter lining may be acid or basic, and if basic the blowing with air (with or without the further addition of basic material) is continued, and in such continuance the phosphorus also is burned out of the molten metal.

The siliceous slag of the earlier portion of the refining operation is a by-produot of little commercial value; the phosphoruswontaining slag of the later portion is of much greater value.

In Letters Patent No. 2,291,221, the invention consists in improvements in method, whereby the basic Bessemer procedure may be practiced with accuracy and expedition, and the slag expeditiously dealt with, in the course of operation, according to its changing character. The apparatus for practicing such method consists essentially of a vertical tube which is so arranged that its lower end can be gradually submerged and retracted in a vessel containing molten iron. Means are provided for delivering air through the tube, whereby the molten iron is blown through with air. The apparatus is adapted for the introduction of various substances into the iron, and for disposing of the slag or retaining it, as desired. Also provision is made in the apparatus for the observation of the iron under treatment.

My present invention consists in certain new and useful improvements in apparatus, to the end that the practice of the Bessemer process shall be facilitated and more readily adapted to present day large scale production, all with substantial continuity of operation, and with reduction in labor, time and operational expenditures.

The invention will be understood upon reference to the accompanying drawings, in which:

Figure l is a view partly in elevation and partly in vertical section of an apparatus embodying the invention;

Fi ure 2 is a fragmentary view to larger scale, showing partly in side elevation and partly in vertical section the blowing tube and its adjusting support;

Figure 3 is an axial sectional view of the blowing tube to the same scale as FigureZ;

Figure 4 is a top plan view of the blowing tube;

Figure 5 is a cross sectional view of the blowing tube, as seen on the broken plane VV of Figure 3;

Figure 6 is a view in perspective of a certain clamping element of the blowing tube structure; and

Figure '7 is a View in perspective of a certain refractory block used in the construction of the blowing tube of the apparatus.

Referring to Figure 1 of the drawings, the con tainer for the bath B of metal to be treated is shown to consist in a conventional -ton open top ladle 2 mounted on a suitable chassis for travel on a railway 4 leading to the blowing station 5 in the basement of a three-storied building t, in which the apparatus is housed. Above the station 5 the blowing tube l is mounted for vertical adjustment in a cylindrical housing formed in two sections 8 and 9, the lower section 8 being rigidly borne b the steel frame of the building and the upper section 9 being mounted on a carriage l0 adapted to travel on rails ll laid on the floor [2 of the building. As will presently appear, means are provided within the upper housing section 9 to lower the blowing tube 1 progressively into the bath of molten metal in the ladle placed in station and, alternately, to raise the tube from the metal and into position entirely within the upper section 9 0f the cylindrical housing.

At its upper end the housing member 9 is detachably and hermetically connected to a header l3 rigidly united with a tubular bonnet it, into which a pipe l5, including a valve l5, is adapted to deliver air under pressure from a pressure tank or other supply l7. Upon the top of the bonnet M is a housing Ill which will be understood to have a window in its top wall, through which an attendant standing on floor l8 may look down through the bonnet It, header [3, housing 8, 9 and tube 1 into the molten metal undergoing treatment. The housing it may contain pyrometric and control instruments (with which the art is familiar) for detecting or revealing the condition of the molten metal within the ladle or converter 2. Extending laterally of the header is are two axially aligned conveyor pipes l3 and Elli, leading respectively from the discharge openings of a bin M for dolomite or lime and a hopper 22 into which reagent materials are introduced. Each conveyor pipe includes a conveyor screw, and the two screws may be mounted upon a common shaft 23. The shaft may be driven in obvious fashion by an electric motor (not shown), and a controlled rotation of the shaft 23 may be established as need be. One

conveyor screw, 24, may be a left-hand screw, and the other, 25, may be a right-hand screw, whereby the rotation of the screw shaft 23 will effect delivery of materials from bin 2| and hopper 22 to the vertical bore I38, Figure 2, of the header, whence the materials descend under gravity and/or under the propulsion of the blast of air streaming downward through the housing 8, 9 and blowing tube 1 into the molten metal. The header l3 and the associated equipment described are all mounted upon the steel framework and floor I8 of the building 6.

Above the floor I8 a plurality of bins 42 is provided for such reagent or rectifying materials as may be required to make desired additions to the molten metal. A scale car 26, movable manually or under motor power over the floor l8, receives in accurately weighed quantities the materials as required from the bins, and transports and delivers the materials to the hopper 22, whence introduction thereof to the molten metal is effected in the manner already described.

In operation, the ladle 2 carrying a proper charge of molten metal still in unrefined state (pig-iron, for example) is brought to position in blowing room 5. It is conveniently tipped on its trunnions to position such as that shown. The blowing tube l is caused to descend from above and its lower end to be plunged beneath the sur face of and to be immersed in the bath of molten metal within ladle 2. Air blast is applied, excluding moten metal from the pipe, so that the tube 1 is open from end to end; and through the tube air is admitted and caused to penetrate the molten metal. The air so admitted attacks primarily the si icon and secondarily the manganese and the carbon of the bath, and progressively burns these elements out. As this operation pro resses a siliceous sag forms, floating upon the bath of molten metal.

As this initial burning-out operation progresses the tube 7 is caused to advance downwardly in the bath of molt n metal. Such downs. .rd ad" vance is serviceable, both to give pro ss e effect in the burning-out of the silicon 4 ning near the surface and advancing more an more deeply) but a so, by displacement, to eliect a spi ling of the slag as it accumulates, from the rim or spout 2a of the ladle into a trough 2?) leading to a suitab e receptacle that stands ready to receive it. Such downward advance of the tube with progressive burning out of impurities is valuable in that the emergent air comes into immediate contact, not with refined but with unrefined metal; the reaction that progresses downwardly with the descent of the tube is maintained at maximum intensity; and the overlying refined metal is protected from immediate access to it of the injected stream of air.

Meanwhile, through the open and unobstructed tube 1 the condition'of the molten metal is subject to detection, optically or otherwise, through windowed housing 10. And thus in the progress of the refining operation the instant may be determined when the burning-out of the silicon is substantially accomplished and the point reached when the sequent burning-out of the phosphorus is to be accomplished. By such procedure it is possible to arrest the blowing while the desired small quantities of manganese and of carbon are retained.

When the desired point has been reached, and by the means described made known to the operator, the downward progress of the blowing tube is arrested and its upward retraction be.. gun. By the retraction, the spilling of slag from the rim of the receptacle is arrested. As the retraction of the tube continues, basic material may be added to the bath, either through the tube or otherwise. But in any case, whether the basic material for the phosphorus reaction is derived from the converter lining alone or is introduced, the burning-out of the phosphorus goes forward; and, as it goes forward, in consequence of the retraction of the tube 1, there is no spilling of the slag. The phosphorus-containing slag of this later portion of the refining operation is retained, floating upon the bath of refined metal; and may in appropriate manner be eventually removed and turned to economic use.

While I have dwelt upon the introduction of basic material to the bath, it is manifest that other desired additions, such as ferro-manganese and other alloying additions may be introduced, either with basic material or alone; and, at the proper point in the progress of the refining operation carbon also may by such means be introduced.

Such is the general organization and mode of operation of the improved apparatus of my present invention. It will be understood the blowing tube is in service subjected to the extreme deleterious effects of the molten metal as agitated 2y the air blast, and in order to insure practical continuity of service of the apparatus my invention also consists in certain valuable features of tube structure, with provision for ready tube repair and reconstruction, as well as in particularly effective means for raising and lowering the tube.

Referring to Figures 3 to 6, the tube '1 is formed of a vertical column of refractory rings 21, each formed of a plurality of segmental blocks 28 of refractory material. The individual blocks are so formed that the hollow rings are cylindrical internally and externally, with the exception of the blocks 28a that form the lowermost ring 21a of the coumn, and these lowermost blocks are formed with downwardly sloped faces 28?), whereby the assembly of superposed rings forms a refractory tube having a cylindrical bore whose lower end is outwardly fiared as shown in Figure 3. The refractory assembly of blocks is integrated by means of a plurality of vertical rods 29 of steel, or other suitable metal, anchored at their upper ends to a head 30 of cast iron or steel.

More particularly, there are eight rods 29 in this case, and they are arranged in spaced relation circumferentially of the tube, and at their upper ends, threaded as shown, extend through orifices in a horizontal web 3| of the head, where they receive nuts 32. The rings 2'! of blocks 28 are assembled successively upon the rods 29 to form the completed blowing tube, the top ring of bocks being assembled upon the rods first and secured by means of a metal ring 33, with pins 34 projected through holes in such ring and anchored in holes provided therefor in the rods 29. It will be noted, Figure 7, that each block 28 is formed as a quarter segment of a hollow cylinder; two bores 35 are formed in the block for the passage through of the two rods 29, upon which the block is assembled; and the bottom portion of the block is undercut or recessed from the outer cylindrical face inward, as shown at 38, to receive the metal ring 33. Specifically, when the four blocks 28 that form the uppermost ring 21 have been placed, each on two of amass? the eight rods 29 and slid upward to a position against the web 3| of the head 39, a metal ring 33, snugly encompassing the eight rods 29 (cf. Figure 5), .is moved into position in the annular recess formed by the undercuts 36 in the four blocks that form the said refractory ring 21, and is secured by means of pins 34. With the top ring 2! thus assembled and secured, the next lower ring of blocks 28 is assembled upon the rods and secured by means of a ring 33 and pins 34; and so each of the rings 21 of blocks is successively assembled and secured upon the rods 29. Then, the lowermost ring 27a is assembled to complete the refractory blowing tube 1.

Before describing the assembly .of the lowermost ring 21a, it is to be noted that preferably, if not essentially, the blocks 28 in the upper rings 2-! are so arranged that the points or meeting faces of the blocks in one ring are staggered with respect to the blocks in the next-adjacent ring. This may be seen in Figure 3. Between the rings 21 the recesses 36 in the individual blocks 21a form annular grooves that open outwardly from the metal rings 33. These grooves are closed by means of refractory filler blocks 31', as shown in Figures 3 and 5. When this has been done the nuts 32 on the upper ends of the rods 29 are turned, drawing the rods, and the metal rings 33 secured thereto, upward to lock the assembled blocks tightly in place. Then the blocks 28a are applied to the lower ends of the rods 29 to complete the tube assembly, it being noted that the rod-receiving passages 38 in the blocks 28a extend only partway through the block bodies. A lateral bore 39 extends outward from each passage or pocket 38, and in such bore a pin 40 is introduced and inserted in the rod 29 in the pocket. The pin 40 is provided with an eccentric portion 40a that engages the Wall of the bore 39 in the block, and a head portion 40b that is adapted to receive a socket wrench or the like. By means of such a wrenchthe several pins 49 that secure the lower ring of blocks to the rods 29 are rotated and the eccentric portions 40a of the pins are caused to cam the blocks upward into tight contact with the lower face of the ring of blocks 28 immediately above. Closure plugs 4| of refractory material then are inserted to close the bores 39. The structure thus constructed forms in eifect an integral tube of refractory material, but with additional advantages over an integral refractory tube: The rods 29 are enclosed and protected so that the metal structure that supports the weight of the tube, which may be as much as fifty tons, does not contact the hot metal or gases, while the rings 33 provide lateral reinforcement of the tube against the internal pressure of the air injected through the tube into the bath of molten metal undergoing treatment, and against the ferrostatic pressure of molten metal on the outside of the tube when immersed in the metal.

In service the blowing tube 1 is secured as by bolts 80, Figure 2, to a sleeve-nut 43 that engages an externally threaded, hollow spindle 44 which is rotatably borne by the upper housing portion 9 mounted on the carriage 10. More particularly, a collar portion 45 is united rigidly to a knee-ring 46 sweated or otherwise locked upon the hollow spindle 44, and this collar portion rides two races 41 and 48 of anti-friction bearings provided in head 49 that forms the upper end of the housing 9. A worm-gear .59 is carried by the collar portion 45, and a worm-pinionv mounted on a shaft 52, meshes with the gear 50. Suitable means (not shown) are provided for rotating the shaft 52 selectively in either direction of rotation, whereby the collar portion and the threaded spindle 44 may be rotated in either direction within the sleeve-nut. Means are provided for preventing the sleeve-nut from rotating, and such means comprise rollers 53 which are trunnioned between paired webs 54 on the cast metal head 30 of the blowing tube, and

at their edges extend between vertical metal strips 55 that are welded in parallel pairs upon the inner surface of the housing 9, the strips in each pair being spaced apart a suflicient interval to provide a vertical way for the rollers 53. Accordingly, when the hollow threaded spindle 44 is rotated, with the sleeve-nut held from rotating, the result is that the sleeve-nut, and with it the supported tube assembly 1, 39, is moved upward or downward, depending upon the direction of spindle rotation. Thus, the blowing tube may be moved downward from telescoped position within the upper housing portion 9, and projeoted through the lower housing 8 into the charge of molten metal to be processed.

The upper end of the rotary hollow spindle 44 is hermetically united to the header !3 whence the blast of air and the reagent materials are delivered, and the bore of this spindle 44 forms with the bore of the refractory tube 1 a continuous passageway to the surface of the molten metal into which the tube is injected. The sealed union between the header l3 and the upper end of the hollow spindle comprises a.

rotary joint formed of ring members 56 and 51 shaped to telescope and compress between them, under stress applied by bolts 58, a ring 59 of lubricated packing material. The spindle is free to rotate relatively to the stationary header I3 with which it has a sealed union, and. the blowing tube may be raised and lowered, as desired, without interfering with the delivery of air or reagent materials to the charge of molten metal in the ladle 2.

In the course of prolonged service the refractory body of the tube erodes away to the extent that repair or renewal is required, and a feature of my invention resides in the organization of means whereby the operation of the plant may be conducted without loss of time on that account. To this end the housing portion 9 is detachable from the housing portion 8, and the rotary joint that unites the hollow spindle 44 to the stationary header I3 is separable. Comparing Figures 1 and 2, it will be perceived that the upper housing portion 9 extends downward from its supporting carriage I 9 and is united to the lower housing portion 8 in a bolted flange joint 69, and that by removing the bolts 6| the two housing portions may be separated. Similarly, by removing the bolts 58, the rotary joint members 56 and 5'! may be disengaged from the sta tionary header l3. Thereupon, by drawing the blowing tube assembly 1, 30 upward into position entirely within the upper housing 9, the carriage 10 may be shifted to the right on the rails II, Figure 1, to bring the housing portion 9 and the worn refractory tube 7 contained therein into position over either one of repair stations 62 or 63. Then, the tube is, by rotation of the hollow spindle 44, lowered to the point where the webs 54 of the tube-carrying head 39 are presented below the lower edge of housing 9, and hangers 64, attached to the steel frame of the building 6, are engaged in eyes 65 in the webs 54 of such head. Thereafter the tube is further lowered 7, until the hangers are placed under tension, and then the bolts 80 are removed, disengaging the tube assembly 1, from the sleeve-nut 43 and leaving such assembly suspended upon the hangers, where it can be repaired or rebuilt as need be.

A spare blowing tube assembly 1', 3B is maintained on hand, in position where the carriage 9 may be spotted over it, and connection made with the sleeve-nut 43. Thereupon, the hangers 64 which normally support the spare tube assembly 1, 36 are disengaged; the tube assembly is drawn upward into the housing portion 9; the carriage i0 is returned to its original position; and all connections are re-established for normal operation of the apparatus.

Advantageously, an oven 66, fired by a fuel burner 61, is provided at the station where the spare blowing tube assembly is stored. Before placing a spare tube in service, it is thoroughly dried and/or preheated in the oven.

Features of operation It will be seen that a suitable optical system arranged in housing H3 can be sighted down through the blowing tube assembly, and focused upon an exposed, and constantly renewed, surface of the metal, presenting a field large enough for spectroscope, radiation pyrometer, Or other such instruments. Also the visual aspect, such as bubbles and other surface phenomena, can be observed accurately and easily.

It is not necessary nor desirable that the blowing tube 1 be submerged in the molten metal'to full depth at once, but it ordinarily is caused to descend slowly into the metal as the reaction progresses, so that the inblown air is constantly presented to new metal rather than to the metal already treated. In this manner less air is used and is used more effectively, and the finished metal is not oxidized. This is in contrast to the old Bessemer method.

The air volume can be varied to control the speed of reaction, and the generation of heat, and the air can be shut 01f entirely, if desirable,-and turned on again at will.

The moderate velocity of the ascending gases assist the slag in rising through the metal, and is not great enough to mix the slag with the metal. Also a greater time will be allowed to complete the reaction. Thi again is in contrast with the old Bessemer process in which, due to the enormous velocity, a mixture of slag and metal is treated rather than metal alone. In my process the slag separates by gravity and is allowed to flow away.

Suitable reagents can be introduced directly into the metal in proper proportion, and at such time as they are most effective. Roll scale may be introduced to furnish additional oxygen, and additions of sodium carbonate and calcium carbonate serve to oxidize the carbon more rapidly, in such a manner that desirable quantities of silicon and manganese may be retained in the iron, and sulphur and phosphorus removed. The sodium carbonate resolves into sodium' (vaporized) which combines with oxygen and hydrogen elsewhere in the iron. In case the ladle is provided with an acid lining, an optimum may be found only when sufficient of these reagents is used to benefit the process, but not enough to produce a basic slag. With a basic lining, such as monolithic dolomiteja basic slag is made and as it contains'a high percentage of double-phosphates of calcium and sodium, the sale of this slag for fertilizer provides a valuable by-product.

.. advantage.

Alloys and light scrap may be introduced directly into the metal, without loss in the slag, and yet may be uniformly distributed. Also deoxidizers and the action of such additions can be instantly observed through the optical system. Calcium-silicon-aluminum alloys may be used efficiently and effectively.

It will be seen that steel can be made in the ladle cars with no transfers such as into and out of the usual Bessemer converter. This is equally true, whether duplexing, or with or without a mixer, and, while the ladle car is stationary during the blowing period, this small delay is no longer than the time consumed in pouring into and out of the usual Bessemer converter.

Since the air and resulting gases will rise in the area round the blowing tube, the lining in the ladle is not subjected to undue destruction. Indeed, its destruction is far less than that of a converter lining. The refractory portion of the tube i subjected to erosion, but fortunately most of this is at the bottom course of refractory blocks, which is easy to replace, and is of such small size that superior refractory material can be used to In any event the cost of renewing the 50-ton tube shown is less than the cost of renewing the bottoms of two 25 ton converters, assuming that the tube lasts only as long as the Bessemer converter bottom.

It will be seen that there will be no difficulties such as arise from blocked, dirty or broken tuyeres of the usual Bessemer converter or from one tuyre burning away more rapidly than the others. Mechanical efliciency will be increased as the friction loss through the tuyres is eliminated. This friction loss is equivalent to about 50% of the static pressure required for the old Bessemer converter.

My process permits the use of metal of widely differing analyses (or off metal) from the blast furnace; conversely, the blast furnace may be operated to its best economy with the wider specification permitted.

The idea of blowing air into the metal from the top is not new. The nearest attempt at reducing it to practice appears to be a hollow tube having at its lower end a few conventional tuyere blocks mounted in a suitable refractory container, which tube is submerged in the metal contained in a ladle car. Such a tube appears to have been tried in the industry, but was not found suitable because: (a) Silicon and manganese were removed, and apparently no carbon removed; (12) operations had to be suspended early as the metal became too cool; (e) an immense amount of vibration took place, to the extent that there was danger of the refractories fracturing. Each of these effects can be traced to each of the following causes: (a) the area of the tuyeres was such that the reaction was extremely local with respect to the large amount of metal in the ladle, so that heat was dissipated into the surrounding metal faster than produced, and a temperature was not reached such as is required to oxidize the carbon-norma1ly onehalf way through the blow; (b) the local silicon becoming exhausted, and no means of circulation were provided, and an increase in the volume of air only cooled the metal faster; (0) the fiat bottom of the tube acted as a cover over an area in which there was a violent commotion, and the inertia of the surrounding iron with respect to the inertia of the tube was such that the flat bottom of the tube received most of the force variations in this force reacting with impacts on the flat bottom of the tube. Even without the violent chemical reactions, the pulsation of these air streams produced this vibrationas if for instance the tube had been submerged in a similar heavy liquid, such as mercury. Contrast this with my blowing tube; the air approaches the metal at relatively low velocity through a tube 14" in diameter (not through 48 orifices /2" diameter as hitherto). The air then enters the metal from around the lower edge of the plunger, in a circle 38" in diameter. Around this circle (and not underneath the plunger), the reaction begins and continues as the air bubbles ascend. The forces evolved are dissipated in causing the metal to flow upward around the outside of the tube. The 14" diameter column of air, even if pulsation occurred, acts as a cushion and dampens it. The volume of air, not being limited by the capacity of the small orifices, is such that proper temperature may be reached faster than heat is dissipated; in fact the tendency is toward overheating.

The invention is described in the appended claims, and it will be understood that within the terms of such claims many variations and modifications of the structure described are permissible without departing from the spirit of the invention.

The application of these Letters Patent comprised a division of my application for Letters Patent No. 2,472,416, dated June 7, 1949.

I claim:

1. Metallurgical apparatus for a plant having an operating station for a container of a charge of molten metal and a repair station, a carriage, means for supporting said carriage above said stations and for travel therebetween, a vertically arranged threaded tubular member mounted on said carriage for rotation on its axis, means for rotating said tubular member, a nut element in threaded engagement with said tubular member, a refractory tube secured to said nut element in telescopic relation relatively to said tubular member, means for securing the nut member against rotation, whereby rotation of said threaded tubular member effects the telescopic movement of said united nut and refractory tube, with the effect that the refractory tube may be lowered endwise into a charge of molten metal in said operating station, and means for supplying air under pressure to the common bore of said tubular member and the refractory tube.

2. A Bessemer plant comprising a station for a vessel of molten metal, a vertically extending housing mounted above said station, said housing being formed in upper and lower sections, means for rigidly supporting the lower housing section, a carriage for supporting the upper housing section, a blowing tube of refractory structure vertically adjustable between telescoped position in said upper housing section and a position in which its lower end is immersed in the molten metal in said vessel, and means for supplying said tube with air under pressure for blowing said metal, said carriage being movable laterally to carry said upper housing section, with said blowing tube telescoped therein, from position above said station.

3. A Bessemer plant comprising a station for a vessel of molten metal, means for delivering air under pressure at a point spaced above said station, a track and a carriage mounted to travel on said track transversely of the vertical space between said station and said air-delivering means, a blowing tube of refractory structure mounted on said carriage, means for detachably connecting said blowing tube to said air-delivering means, and means for vertically adjusting said tube between a position in which its lower end is immersed in the molten metal in said vessel and a position in which the tube is elevated above said station for travel with its supporting carriage.

4. A Bessemer plant comprising a station for a vessel of molten metal, a vertically extending housing section above said station, a blowing tube of refractory structure, means for vertically adjusting said blowing tube between telescoped position in said housing section and a position in which its lower end is immersed in the molten metal in said vessel, means for supplying said tube with air under pressure for blowing said metal, an overhead track, a carriage arranged to travel on said track transversely of the vertical space between said station and air supply means for shifting said housing section transversely of said station when said tube is telescoped therein, and means arranged and effective above the vessel in said station for detachably securing the lower end of said housing section against movement when positioned above the station.

5. A Bessemer plant comprising a blowing station arranged to receive a container of a charge of molten metal, a vertically-extending blowing tube of refractory construction, means for mounting the blowing tube above said blowing station comprising a carriage and a vertically-extending housing section, a track on which said carriage is arranged to travel horizontally, means arranged in said housing section for vertically reciprocating said tube to lower it endwise into a charge of molten metal and to raise it telescopically into said housing section, means for supplying air under pressure to the upper end of the tube while it is moving vertically, means for detachably connecting said housing to said air-supplying means, said carriage being mounted for horizontal movement on said track transversely of the vertical space between said station and said air supply means for shifting said housing section transversely of said station when said tube is telescoped therein, and means arranged and effective above a vessel in said station for detachably securing the lower end of said housing section against movement when positioned above the station.

ROBERT M. GIBSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 239,619 Pedder Apr. 6, 1881 1,073,587 Billings Sept. 23, 1913 1,312,474 Fisk Aug. 5, 1919 1,465,128 Harris Aug. 14, 1923 1,507,214 Somers et al. Sept. 2, 1924 1,746,904 Pike Feb. 11, 1930 1,933,577 Wille Nov. 7, 1933 2,291,221 Gibson July 28, 1942 FOREIGN PATENTS Number Country Date 220,279 Great Britain Feb. 19, 1925

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