US2818248A - Refractory block and ladle lining construction - Google Patents

Description

P. S. KELSEY Dec. 31, 1957 REFRACTORY BLOCK AND LADLE LINING CONSTRUCTION Filed Sept. 12, 1955 3 Sheets-Sheet 1 mmvrom PAUL s. KELSEY P. S. KELSEY Dec. 31, 1957 REFRACTORY BLOCK AND LADLE LINING CONSTRUCTION 5 Sheets-Sheet 3 Filed Sept. 1

IN VEN TOR.

United States Patent REFRACTORY BLOCK AND LADLE LlNlNG CONSTRUCTION Paul S. Kelsey, Manchester, Conn.

Application September 12, 1955, Serial No. 533,795

6 Claims. (Cl. 266-43) This invention relates to refractory block linings in ladles for molten steel and the like, and the blocks for such linings. This application is a continuation-in-part of my co-pending application Serial No. 408,515 filed February 5, 1954 now abandoned.

Ladles for receiving molten steel require a refractory lining which must conform to the shape of the ladle and prevent the molten steel from penetrating to the outer metal sheath of the ladle. The lining must be able to withstand widely fluctuating temperatures and the washing and erosive action of molten steel and slag being poured in and out of the ladle, must remain in place while the ladle is tilted about its opposite supporting trunnions, and must withstand as many successive heats as possible before being taken out of service for repair or replacement of the lining. It is necessary to build the lining in the form of a wall of individual refractory blocks, and this raises the problem of discovering a set of block shapes which will provide a close fitting wall, which requires a minimum of differently shaped blocks to complete the lining, and which can be laid easily and quickly by relatively unskilled labor. The problem is greatly complicated by the fact that the ladles in question not only have conically curved side walls in all cases, but in many instances also include straight side walls interposed between conically curved ends. It is further complicated by the fact that the blocks must be thoroughly burned in a kiln before being laid, in order to eliminate any possibility of shrinkage when used in ladle operations. The shape of the block must therefore satisfy not only the requirements of the ladle but also of the kiln. For example, the blocks are generally stacked sidewise in the kiln for quick oxydizing and burning, and the stacks tend to fall over if the blocks have their faces curved to fit the conical side walls of the ladles. Also, the blocks are weak when initially set, and brittle after final burning, so that the long tails characteristic of conventional curved-end Universal blocks tend to deform or come off during manufacture and to break off during subsequent shipping and handling of such blocks. The latter blocks also take up an excessive amount of space in the kilns and in subsequent transit and storage, because of their high ratio of overall length to effective length.

At the present time most steel ladles are lined with a set of five differently shaped blocks known as straights, arches, wedges and number one and two splits. These blocks are interspersed selectively to fit tightly all around the ladle. However, the time and skill necessary to lay these blocks, and the special inventory problems which they present, have led to an active search for a more suitable form of lining construction. Conventional Universal blocks, which have curved front and rear faces conforming to the wall shape, and opposite concave and convex ends curved about radii equal to half the width between the front and rear faces, have long been known but have had substantially no use in ladles because of the above-mentioned troubles. with the long tails at the concave end. Another trouble. is the serpentine effect of Universal blocks if laid along the straight sides of a ladle. A variation of Universal blocks are Circle blocks, which are curved about their front and rear faces to conform to the ladle wall, but are straight at their ends. Circle blocks have been used extensively in recent years, but the difficulty with these blocks is the poor fit at their ends when used above or below the level of the ladle which exactly fits their curvature. The result of the poor fit is severely shortened ladle life, which offsets the advantage of quicker and easier laying obtained with these blocks. A more recent and successful form of ladle lining employs blocks with tongue-and-groove connections at their opposite ends, but while such blocks are easier to make and lay than the above-mentioned conventional blocks which include five different shapes, and improves ladle lining life as compared with Circle blocks, the tongue and groove connections do not give as good ladle lining life as is desired, and the problem of developing better ladle linings has remained.

In accordance with the present invention ladles are lined with blocks which can be curved but preferably are straight sided between their ends, and which are so curved at their ends as to enable the lining to be laid quickly and tightly with a small number of different block shapes. The blocks of the invention are economical to manufacture, transport and store. Each block is curved convexly at one end and concavely at the other, the radii of curvature at the opposite ends being equal but centered so that a curved wedge effect is created at the opposite ends of the block, the angle between the chords across the arcuate ends being such that a series of the blocks can be laid around the circular ends of a ladle and also, by alternately reversing the blocks, along the straight portions of the ladle. The interfitting curved ends provide a tight, wear resistant joint and at the same time permit angular movement of the abutting blocks to enable them to adjust to different ladle wall curvatures at different levels of the ladle.

A series of identical blocks of the invention can be laid with perfect end-to-end fit along a circle having a particular radius, but if laid along a larger or smaller circle the ends shift into partially off-set relation to enable the blocks to follow the curve of the circle. This does not impair the tight end fit between the blocks, but does reduce the effective thickness of the lining wall. Consequently, while a small amount of end offset to accommodate a limited change of ladle wall curvature is not objectionable, it is necessary to modify the curve made by each series of identical blocks in some manner when the ladle wall radius changes substantially, as .it does between the top and bottom of each section of the ladle lining having the same lining thickness. There is the further problem of fitting the blocks accurately along each transition from straight to curved ladle wall, and vice versa, which is complicated by the fact that different positions of the last block laid in regular formation before reaching such point of transition produce different problems of laying the blocks where the transition occurs. In accordance with the invention these difficulties are overcome by providing two different block shapes for each section of the ladle lining having the same thickness, one of the blocks being of standard length and having its ends at such angle as to conform to the curvature of the ladle wall at the top of said section, and the other block having about half the overall length of the first block but otherwise being the same and preferably having the same angle between the chords across its curved ends. The shorter length coupled with the equal angle of the end chords produces an auxiliary block which tends to tighten the curve for which the full length blocks are designed, and is therefore helpful in laying the lower courses of each lining thickness to match the ladle curvature of decreased radius. I find that one, or a series of two or three, of the short blocks may be variously arranged as the situation requires, with little difficulty in selection, to take care of any problem of smoothing the transition between straight and curved portions of a ladle. The short blocks also take care of the problem of lining the irregular bulges which are often found in ladles in present commercial use, particularly at the bases of the trunnions. Since the short blocks preferably have the same angles between the chords across their arcuate ends as the corresponding full length blocks, they are readily made in the same standard extrusion or pressure molding equipment used to make the full length blocks, merely by changing the spacing between the concave and convex end liners of the forming dies.

A further important problem is the length of radius of the curved ends of the blocks. if this radius is too great, the end curvature becomes so flattened as to lose most of the interlock of the blocks along straight portions of the ladle wall. concave end of each block become excessively tapered, and the ratio of the overall length of each block to its effective length becomes so great as to interfere seriously with production, storage and shipping. Considering the balance of these considerations as far as any one block is concerned, the end radius in accordance with the invention is ideally about equal to the thickness of the )lOCk between its front and rear side faces, and can be in the range of equal to twice such thickness. There is a further important consideration affecting all of the side-lining blocks in the ladle as a group, and that is the transition between blocks of one thickness to blocks of another thickness. There may be only two such transitions where three different thicknesses are involved, but when the ladle has one or more limited areas of increased lining thickness, such as a wearing pad, these transitions become very numerous and can be very troublesome. The transition can be made by sawing blocks of different thicknesses in half, and joining the sawed end of half of one thickness with the sawed end of another thickness. That, however, multiplies the number of block shapes to be laid. l have discovered that this problem can be much better solved by using a common end radius for all of the side-lining blocks in the ladle, preferably about equal to the thickness (between the front and rear side faces) of the thickest set of blocks in the ladle. Although this preferred cornmon radius reduces the curvature of the ends of the thinner blocks, the remaining curvature plus the tight end fit has proved successful in holding in place even the thinnest blocks at the top of the lining, all around the curved and straight portions of the ladle.

Further objects, advantages and novel features of the invention will become apparent from the following detailed description of the present preferred embodiments of the invention illustrated in the accompanying drawings. la the drawings:

Figure l is a partially broken-away section of a ladle for molten steel with a lining incorporating the invention, the section being taken along a vertical plane normal to the trunnion axis of the ladles;

Figure 2 is a section on the line Il-ll in Figure 1;

Figures 3, 4 and 5 are top, front and end views, respectively, of one of the uppermost side lining blocks shown in Figures 1 and 2;

Figure 6 is an enlarged semi-diagrammatic plan view of part of a course of the blocks shown in Figures 3-5, and a section of straight and curved portions of the adjacent safety lining of the ladle;

Figure 7 corresponds to Figure 6 but shows only a straight portion of the course of blocks and adjacent safety lining;

Figures 8, 9 and 10 are top, front and end views, respectively, of one of the half-blocks used with the block shown in Figures 3-5;

If too small, the edges at the Figures 11 and 12 are top and front views of one of the lowermost side lining blocks shown in Figure 1;

Figures 13 and 14 are top and front views of one of the half-blocks used with the block shown in Figures 11 and 12.

Figure 15 is a view corresponding to Figures 6 and 7, but showing the juncture of the final course of thickest blocks with the starting course of intermediate blocks, along a curved portion of the ladle; and

Figure 16 is a view corresponding to Figure 15, but showing the juncture of the final course of intermediate blocks with the starting course of the thinnest blocks.

Referring now more particularly to the drawings and initially the Figures 1 and 2, there is illustrated a ladle in for molten steel and the like, having a sloped bottom ii and side walls with opposite straight portions 12 and opposite conically curved ends 13. A trunnion 14 extends integrally from one of the straight side portions 12 and a corresponding trunnion (not shown) extends oppositely from the other straight portion (not shown). T he straight and curved sides of the ladle 10 taper outwardly from bottom to top in order to facilitate removing any skull of hardened metal formed in the ladle, and a taphole (not shown) is provided at the bottom of the ladle with a suitable nozzle and stopper to release or retain molten metal in the ladle as required. The ladle also has a slag spout (not shown) on its upper rim. A metal shell 15 extends around the outside of the bottom and sides of the ladle, and against the shell 15 there is laid a refractory bottom safety lining 16a and side safety lining 17. A working floor lining 16b is laid inside of the side safety lining 17 and over the bottom safety lining 16a. A working lining of relatively thick blocks 18a and 18b is laid next to the safety lining 17 upwardly from the floor lining 16b part of the way up the sides of the ladle, covering the area of greatest wear. Some what thinner blocks 19a and 1% are laid further up the sides of the ladle against the lining blocks 17, and still thinner blocks 20a and 20b are laid against the lining blocks 17 the rest of the way up to a level near the top of the ladle. A plate 21 secured to the outer shell 15 extends over the safety lining 17 and partly over a final course of conventional blocks 21' wedged between plate 21 and the top course of lining blocks 20a in order to retain the refractory side lining in place when the ladle is tilted on its trunnions. All of the said blocks are made of kiln-fired refractory clay. The blocks 18a and -b, 1% and -b, and 20a and -b are preferably laid in continuous multiple spirals, usually double spirals, substantially from the bottom to the top of the ladle, as indicated in Figure 1.

Referring now to Figures 3-5, each of the blocks 20a has parallel vertical front and back faces 22 and 23, parallel horizontal top and bottom faces 24 and 25, and opposite arcuate ends 26 and 27. The arcuate end 26 intersects the front and back faces 22 and 23 to form two vertical block edges 28 and 29, and the arcuate end 27 intersects the front and back faces 22 and 23 to form two other vertical block edges 30 and 31. The ends 26 and 27 are respectively concave and convex, their radii of curvature are equal, and their curved surfaces extend to and between the pair of vertical edges 28 and 29, in the case of end 26, and edges 30 and 31, in the case of end 27. The plan of the block 20a is laid out by drawing a triangle having two equal sides of 'a length equal to the maximum inside radius of the ladle curvature that the block is designed to fit, with an angle of about 3 between said two sides. The third side of the triangle represents the upper edge of the back face 23, with the points representing the vertical edges 29 and 31 coinciding with two corners of the triangle. A line is drawn across the equal sides of the triangle, parallel to the third side and at a distance therefrom equal to the thickness of the block 20a between its front and back faces 22 and 23. The intersection of said parallel line with the equal sides of the triangle locates the points representing the vertical edges 28 and 30, and thus determines the length and location of the upper edge of the front face 22. Arcs of equal radius are then drawn through the pair of points 28 and 29, and 30 and 31, to represent the curved ends 26 and 27, the center of curvature of the arcuate end 27 is shown at 27 in Figure 3; the corresponding center point of the arcuate end 26 is too far to the left of the figure to be shown in the drawings. The chord lines drawn through the edges 28 and 29 across the arc of the end 26, and the chord line drawn through the edges 30 and 31 across the arc of the end 27, are thus designed to intersect adjacent the axis of each curved end of ladle when the blocks 20a are laid therein, and consequently the blocks 20a are readily laid in closefitting relation with the safety lining 17 around the curved ends of this ladle 10 (see Figure 2). Along the straight portions of the ladle 10, the blocks 20a are alternately reversed to fit exactly along the safety lining, as illustrated in Figures 2 and 7.

A like procedure is followed in determining the form of the blocks 18a and 19a. All of the blocks 18a, 19a and 20a preferably have the same length across their back faces (e. g., between edges 29 and 31 in Figure 3), for general reasons of convenience. More importantly, all of the blocks 18a and -b, 19a and -b, and 20a and -b, have the same height and the same radius of curvature at their opposite ends, so that they can be laid quickly and efiiciently in continuous spirals of interlocking, tightfitting blocks substantially from top to bottom of the ladle side wall.

There is an important interrelation between the radius of end curvature of the blocks and their thickness, when all of the end radii are the same for all thicknesses of blocks. If the end radius is substantially more than twice or substantially less than equal to the thickness of any block, the block will either be so flattened at the ends, as a result of too large a radius, that it will not interlock adequately, especially along straight portions of the ladle; or the block will be so curved at the ends, as a result of too small a radius, that it will have an excessive ratio of overall to effective length, and will have excessively tapering corners at its concave end, which are likely to deform or break off. The thickness of the blocks between their front and back faces (e. g., between 22 and 23 in Figure 3) is an important factor in determining the end radius, because increasing the thickness has the same effect on the shape of the block ends as decreasing the end radius, and vice versa. A further consideration is choosing varying block thicknesses with a view to equalizing wear of the refractory lining from top to bottom of the ladle, throughout the working life of the lining. For optimum results and optimum balance of all of these considerations, I have found that the thickest block (18a) should have twice the thickness of the thinnest block (20a), and that the common end ra dius should be equal to the thickness of the thickest block (as illustrated in the accompanying drawings).

One of the half-blocks 20b used with the full blocks 20a is illustrated in Figures 8-10. Each of the blocks 20b has faces 3843 corresponding respectively to the faces 2227 of each block 20a, with the same thickness between the front and back faces 38 and 39 as between the front and back faces 22 and 23, the same height between the top and bottom faces 40 and 41 as between the top and bottom faces 24 and 25, the same parallel rela tion between the front and back faces and the top and bottom faces, the same angular relationship of the chords across the curved ends to the front and back faces, and the same radii of curvature at the ends. However, the length of the back face 39 of the half-block 20b equals half the length of the back face 23 of the full block 20a, and the length of the front face 38 of the half block 20b equals the full length of the front face 22 less half the length of the back face 23 of the blocks 20a. As a result, although the angles subtended by extensions of the chords across the arcuate ends of the blocks 20a and 20b are equal, the ratio of the horizontal length of the front face 38 to the back face 39 is less than the corresponding ratio in the case of the front face 22 and back face 23, and consequently the half-blocks 20b can be used to tighten up a curve along a course consisting principally of the blocks 20a wherever necessary adjacent the juncture of straight and curved portions of the ladle 10, or where the ladle lining may have become bulged in the course of ladle operations. An inherent advantage of the set of blocks 20a and 20b is that they can be formed in the same equipment, merely by altering the spacing between the dies forming the curved ends.

An example of the cooperative use of the full and half blocks 20a and 20b is illustrated in Figure 6, where two of the half-blocks 20b are shown inserted between a series of full blocks 20a to form a suitably close fit against the safety lining 17. The use of the half blocks 18b, 19b. and 20b to smooth the transitions from blocks of one thickness to the next, is illustrated in Figures 15 and 16. When laying courses of blocks in accordance with the invention, it is necessary to use the half blocks in other ways than those shown in Figures 6, 15 and 16, which will be sufficiently obvious when the occasion arises. For example, if the slant of the end of a curved block 20a must be reversed at some place, two of the blocks 20b can be used together in place of a full block, one reversed relative to the other.

When the blocks 20a, 19a and 18a are laid along a straight portion of the ladle, alternate blocks are reversed; see the blocks 20a in Figure 7. If the curved ends were made straight the alternate blocks having their longest vertical face disposed toward the interior of the ladle would tend to fall into the ladle, since there would be nothing to restrain such inward movement. In the case of the blocks in accordance with the invention, however, the curvature of the ends gives sufiicient keying effect to overcome this tendency and form a solidly interlocked straight wall.

While I have illustrated and described certain present preferred embodiments of the invention, it will be understood that the invention is not limited thereto but may be variously embodied and practiced within the scope of the following claims.

I claim:

1. A ladle for molten steel and the like, said ladle comprising side walls with straight lengths merging tangentially with conically curved lengths, and an interior lining extending along said side walls and built of refractory blocks laid in successive courses, at least several courses being built of a set of two forms of block, the first form of block having flat parallel top and bottom faces, opposite cylindrically curved ends of equal radius of curvature but respectively concave and convex, and front and back faces which intersect the curved surfaces of the ends and are generally uniformly spaced a distance apart substantially equal to said end radius, and the back face being longer than the front face so that a series of such blocks extend in a curve conforming to the curved ladle wall; and the second form of block having like faces but having about half the end-to-end length of the first form of block and having a different ratio of length of front face relative to back face than the first form of block, said second form of block being used adjacent the juncture of the straight and curved lengths of the ladle side walls.

2. A ladle for molten steel and the like, said ladle comprising side walls with straight lengths merging tangentially with conically curved lengths, and an interior lining extending along said side walls and built of refractory blocks laid in successive courses, at least several courses being built of a set of two forms of block, the first form of block having substantially fiat parallel top and bottom faces, opposite cylindrically curved ends of equal radius of curvature but respectively concave and convex, and

substantially flat parallel front and back faces which intersect the curved surfaces of the ends and are spaced a distance apart substantially equal to said end radius, and the back face being longer than the front face so that a series of such blocks extend in a curve conforming to the curved ladle wall, and the second form of block having like faces but having about half the end-to-end length of the first form of block and having a lesser ratio of length of front face relative to back face than the first form of block, said second form of block being used adjacent the juncture of the straight and curved lengths of the ladle side walls.

3. The combination of claim 2 in which chordal planes through the cylindrically curved ends of each form of block have the same angular relation in the case of both forms of blocks.

4. A ladle for molten steel and the like, said ladle comprising an interior side wall at least part of which is conically curved, and a working lining of refractory blocks around the inside of said side wall, all of said blocks having flat parallel top and bottom faces, opposite cylindrically curved ends respectively convex and concave, and flat parallel front and back faces intersecting said curved ends, said lining including lower courses of relatively thick blocks and upper courses of less thick blocks, such thickness being measured between front and back faces, the radius of end curvature being equal in the opposite ends of each block and being the same for both the thick and less thick blocks, the common end radius of the blocks being approximately equal to the thickness of the relatively thick blocks and not substantially greater than twice the thickness of the less thick blocks, the back face of each block being longer than the front face thereof whereby chordal planes through the respective ends are slightly angulated with respect to each other, the chordal plane angulation being the same for all blocks, said thick and less thick blocks being laid end-to-end in continuous helical formation from near the bottom to near the top of the ladle side wall.

5. A ladle according to claim 4, in which the courses of blocks of each different thickness include blocks of two 8 different forms, said forms being identical in all respects except that the end-to-end length of the back face of one form is approximately half the corresponding back face length of the other form.

6. A set of refractory blocks for lining molten steel ladles and the like, all of said blocks having flat parallel top and bottom faces, opposite cylindrically curved ends respectively convex and concave, and flat parallel front and back faces intersecting said curved ends, said set including relatively thick blocks and less thick blocks, such thickness being measured between front and back faces, the radius of end curvature being equal in the opposite ends of each block and being the same for both the thick and the less thick blocks, the common end radius of the blocks being approximately equal to the thickness of the relatively thick blocks and not substantially greater than twice the thickness of the less thick blocks, the back face of each block being longer than the front face thereof whereby chordal planes through the respective ends are slightly angulated with respect to each other, the chordal plane angulation being the same for all blocks, the blocks of each different thickness including blocks of two different forms, said forms being identical in all respects except that the end-to-end length of the back face of one form is approximately half the corresponding back face length of the other form.

References Cited in the file of this patent UNITED STATES PATENTS 110,882 Whitestone Jan. 10, 1871 229,766 Smith July 6, 1880 471,173 Gustavino Mar. 22, 1892 850,048 Playford Apr. 9, 1907 1,032,675 Holland July 16, 1912 1,845,472 Albright Feb. 16, 1932 1,988,856 Passino Jan. 22, 1935 2,526,289 Smith Oct. 17, 1950 FOREIGN PATENTS 35,180 Germany Apr. 3, 1886 55,477 Germany Aug. 15, 1889

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