US2413988A

US2413988A - Blast furnace bottom and method of constructing same

Info

Publication number: US2413988A
Application number: US538907A
Authority: US
Inventors: Fred M Miller
Original assignee: General Refractories Co
Current assignee: General Refractories Co
Priority date: 1944-06-06
Filing date: 1944-06-06
Publication date: 1947-01-07
Anticipated expiration: 1964-01-07

Description

I F. M. MILLER 2,413,988

BLAST FURNACE BOTTOM AND METHOD OF CONSTRUCTING SAME Filed June 6, 1944 3 Sheets-Sheet 1 1947- F. M. MILLER 7 2,413,988

BLAST FURNACE BOTTOM AND METHOD OF CONSTRUC TING' SAME Filed June 6. 1944 a Sheets-Sheet 2 r INVENTOR,

Zr dMuMi'uen Jan. 7, 1947. F. M. MILLER 2,413,988

BLAST FURNACE BOTTOI AND IBTHOD OF CONSTRUCTING SUE Filed June 6. 1944 3 Shouts-Sheet :5

" INVENI Mlfz'ller; 1 B I Patented Jan. 7, 1947 BLAST FURNACE BOTTOM AND METHOD OF I CONSTRUCTING SAME Fred M. Miller, Bala-Cynwyd, Pa., assignor to General Refractories Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 6, 1944, Serial No. 538,907

9 Claims.

The object of the invention is to provide improvements in the composition of blast furnace bottoms and the method of constructing same.

Another and more specific object is to provide in a blast furnace bottom a greater concentration or mass of refractory material within any given furnace dimensions, and to insure a more unitary resulting structure than has heretofore been possible,

Accepted practice heretofore has been to assemble in closest possible juxtaposition multiple courses or layers ofaccurately formed brick (usually 18" x 9" x 4 each brick being carefully molded, handled and fired, so as to produce and preserve its desired dimensions and the accuracy of its corners and edges, even to the extent that they are frequently ground, in order to insure strictly planularsurfaces and resulting intimate and uniform contact when assembled. However, with all of these precautions it is a practical impossibility to secure such a permanently tight fit and solidarity of the mass, that slight shrinkage therein will not cause joints to open up and metal to eventually escape.

in line with this effort to obtain exactness and superior workmanship in the manufacture of blast furnace bottom blocks, emphasis is stressed upon insuring these essential characteristics, with the result that firing temperatures have to be regulated to a point where the density of the fired blocks usually runs to .a maximum of approximately 1.22 ounces per cubic inch, since higher firin temperatures tend to cause kiln marking and a prohibitive degree of distortion, making them unfit for assembly in accordance with present day practices;

A further object, therefore, is to provide a means or method whereb the mass or density of blast furnace bottoms may be economically increased, by permitting the practical manufacture of denser bricks or blocks, which can be assembled into a solid mass subject to reduced shrinkage in service, when and as subjected to furnace operating conditions. Thus, with exactness of workmanship no longer the chief criterion in judging bottom bricks or blocks, and thefact that they may be more economically produced to securemaximum density with a given raw materiaL'followed by assembly or installation in accordance with the present invention, it is accordrate an additional 110,000 to 125,000 pounds within the same space, thereby imparting to the unit structure of refractory material greater volume stability and resultinglylongerlife under A given conditions.

' Still another object, therefore, is toprovide an improved method of assembly, whereby such high-fired and resultingly dense bottom blocks or brick, even though considerably distorted, may be incorporated into a matrix of specially prepared ramming mixes to form a solid mass of high overall density. While refractory ramming mixes are not new, and it is well known that if properly prepared a high degree of density can be attained, as by ramming with pneumatic tools, such refractory ramming mixes have not heretofore been employed to overcome the difiiculties and problems which characterize blast furnace bottom construction. Also, instead of constructing a furnace bottom of bricks and fefrac tory ramming mixes of the same materials throughout, they may be varied in accordance with their position or elevation in said bottom, and therefore with relation to the service to which they are subjected during operation of the furnace. For example, one or more of the firsta laid lower courses might comprise intermediate heat duty brick separatedby Lumnite or Portland cement, the next courses composed of high heat duty brick separated by an intervening ramming mix comprising predominantly calcined clay materials, the next course or courses being composed of highfired refractory bricks and intervening ramming mix consisting of high temperature-resisting materials such as sillimanite, magnesite, or the like, and the one Or more uppermost courses comprising carbon blocks separated by a carbon base ramming mix,

The ramming mixes herein referred to comprise calcined materials in granular form, together with a small proportion of suitable bonding material, and of such analysis that they intimately adhere to the adjacent brick surfaces, and produce a resultingly homogeneous unitary bottom structure having such a high degree of cohesion as to resist the escape of molten metal therethrough, as sometimes occurs.

With the objects thus briefly stated, the inven-' tion comprises further details of construction, which are hereinafter fully brought out in the following description, when read in conjunction with the accompanying drawings, in which Fig. 1

is a vertical, diametrical section through the bash and hearth or cupola sections of a representative type of blast furnace having a bottom of the improved coristruction; Fig. 2 is a fragmentary section approximately on the line 2-2 of Fig. 1, with successive courses of brick and intervening layers of ramming mix uncovered to varying degrees; Fig. 3 shows one method of assembling consecutive rows of brick in a given course, and

the application of the ramming mix therebetween; Fig. 4 is an enlarged fragmentary portion of a given crurse, showing a modified method of assembling bricks and intervening ramming mix:

Fig. is an extended section on the line 5-5 of Fig. 4; and Fig, 6 is a perspective view of a fragmentary portion of the matrix structure of the ramming mix per se, to show among other things the impenetrability of the improved bottom construction to molten metal.

Referring to Figs. 1, 2 and 3, the major part of the lower portion of a representative type of blast furnace is shown as comprising the customary circular bosh and hearth sections I and 2, rev one embodiment of the invention, the full height of said bottom and its foundation are not shown.

Primarily the furnace bottom is constructed within a cylindrical metallic casing 4 and a concentric cast iron hearth jacket 5, spaced apart by intervening grouting material 6 of any suitable character, and surrounded by concrete (and/or brick) reinforcement I, that also serves to support the usual plurality of circumferentially spaced column 8, which support the weight of the lnwall and top sections of the furnace proper above the mantel Be, as well as the bustle air and water ducts, ore-handling machinery and other super-structure associated therewith.

The said bosh and hearth sections comprise brick walls la and M, respectively, which are interspaced with water-cooled plates 9, while circumferentially spaced hot-air nozzles l0 extend through the upper portion of the hearth section to convey to the ore therein air that has been preheated by so-called stoves in well-known manner. The bosh section is probably always conical as to its inner surface, which merges flush into.

the corresponding surface of the cylindrical hearth section Said hearth section rests directly upon the bottom 3, which as shown is composed of any dcsired-number of vertically arranged courses of brick l I, These brick are preferably of substantially the same size for uniformity, regularity of arrangement and easy handling, and are stood on end in each course but are angularly related.

in adjacent courses. .Also, whereas it has heretofore been considered essential that broken joints be maintained between bricks in adjacent courses,

in the present improved construction, broken joints, though maintained as far as possible following the usual practice, are not so essential,

since adjacent courses are separated by interposed layers ll of the ramming mix.

As will be seen from the drawings, which are drawn fairly closely to scale, adjacent bricks in the same course are spaced approximately two and one-half to three inches apart, or a sufllcient distance to permit the ready insertion and operation between them of any well known form of air-driven ramming or tamping tool, while compressing the ramming mix in the'vertically extending sections l3. By contrast, the thickness of the horizontal layers of the mix may be of any desired depth, either the same as, or more or less than, that between the bricks of the same course.

Referring to Fig. 3, there is here shown one method of assembling the bricks in the improved construction. An initial row of bricks is laid in spaced relation with one another and Preferably in alignment. Such row may be at the center of the hearth bottom coincident with a diameter, or may be adjacent to one side and coincident with a cord, as for instance the row of three brick l4. Between the adjacent wall surface and said bricks while backed by a short beam and between adjacent bricks in the same row ramming mix is compressed into place, it being noted that with the improved construction the bricks do not haveto fit the surrounding hearth jacket closely, but instead may leave relatively large spaces l5 that are also filled with the mix alone, or with a combination of mix and broken or odd pieces of brick. A

larger beam is then used to back up a second row,

repeated until the point illustrated by Fig. 3 is reached, wherein a much longer beam I1 is em-- ployed to back up the thirteenth row of bricks l8, as they are laid in spaced relation with each other and with the last previous, Or twelfth, row l9. The succession of beams of gradually increasing length, in one or more sections, is used in reverse order as the operation progresses through the second half.

The varying lengths of consecutive beams may be secured in fixed position by any suitable means, which merely for purposes of illustration is shown in Fig. 3 as comprising a.plurality of blocks 20, which spread the force exerted upon them by jack bars 2| to spaced regions of the said beam. Each of said bars is adjustably positioned in any suitable manner, as for instance, by means of jacks 22, backed or shored by any available timher or the like, such as the central shoring blocks 23 and the single or built-up blocks 24, having diagonal or curved surfaces 25 for engagement with laterally spaced portions of the jazket 5, said central and lateral blocks being maintained in spaced relation by compression beams 26, or otherwise as may be desired. Finally, after all of the bricks of a given course have been laid by this method, a layer 12 of the mix is tamped over and across the entire area like a blanket, following which another course of brick is superimposed thereon but preferably arranged at right angles (or at least angularly) with respect to the bricks of the last completed course. This process is repeated until the desired depth or thickness of the furnace bottom is attained, whereupon the cylindrical hearth wall 2a is laid thereon in the usual manner, as shown in Fig. 1.

Referring to Figs. 4 and 5, a modified method of laying the brick in a given course is shown. By this method all of the brick 21 of a given course 28 are laid in preferably (though not necessarily) uniformly spaced upright position upon a layer of mix l2 immediately therebelow. Between the lowermost portions of said brick, both in longitudinal and transverse directions, are inserted spacing blocks or spacers 30 of any suitable noncompressible material, such as metal, plastic, ceramic, or otherwise. Upon the opposite sides of said blocks and between said bricks ramming mix 3| is inserted and rammed or tamped into place by any suitable tool 3la, whereupon said blocks are lifted and the spaces left vacant by their removal filled with the mix duly set by ramming. The blocks are then again inserted between said bricks in the elevated positions 32, and more of the mix 33 forced into position between them, and the blocks again lifted, their only one or possibly two elevations of the spacers may be used, if, preferred, instead of the three here described.

Fig. 6 has been included in order to showthecharacteristics of the ramming mix per se after being rammed in a complete bottom, that is, as though the mix were formed in the absence of the bricks, or the bricks removed from this fragmentary portion of the composite bottom struc--.

cement mixture rammed between them, a layer of mix upon said course, a second course of spaced high heat duty brick upon said layer of mix, a mix of granular calcined clay materialsrammed between the bricks of said second course, a layer.

of mix upon said second course, a course of spaced high refractory brick upon said second layer, a mix rammed between the bricks of said last-mentioned course, and composed of high temperatureresisting materials selected from the group consisting of sillimanite and magne'site, a layer of the same mix material-upon said last-mentioned course, a layer of spaced carbon brick-upon said last-mentioned mix layer, and a carbon-base'mix rammed between said carbon bricks.

2. A furnace bottom, comprising the combination of a course of intermediate heat duty brick, a course of high heat duty brick, a course of high refractory brick, a course of carbon brick, and a layer of rammed mix between two adjacent courses.

3. A furnace bottom, comprising the combination of superimposed courses of refractory brick, the joints between the bricks of each course being filled with a mix composed of materials selected from the group consisting of silliinanite and magnesite, and a layer of, rammed mix between two of the adjacent courses.

4. A furnace bottom, comprising a course of spaced relatively lowheat duty brick, a rammed hydraulic cement mix between the bricks of said course, a layer of a mix covering said course, a second course of spaced high heat duty brick upon said layer of mix, a rammed mix of granular calcined clay materials between the bricks of said second course, a layer of a mix covering said second course, a third course of spaced high-fired refractory brick upon said last-mentioned layer, a rammed mix of high temperature-resisting materials selected from the group consisting of sillimanite and magnesia-containing material between the bricks of said third course, a rammed layer of the same material covering said third course, a fourth course of spaced carbon brick upon said last-mentioned layer, and a rammed mix having a carbon base extending across said fourth course.

5. A furnace construction, comprising superimposed courses of refractory brick, said courses and the bricks of each course being initially spaced apart, and a ramming mix composed principally of the same material as that which principally constitutes the material of said brick rammed into the spaces between adjacent courses and between the bricks of each course, said ramming mix uniting as an integral unit of itself and with the material of said brick to form a dense, monolithic mass of substantially uniform integral mixture.

6. A monolithic furnace bottom, comprising superimposed courses of refractory brick having substantially the same refractory characteristics,

said courses and the bricks of each course being initially spaced apart, and a mix composed of material having at least as high refractory characteristics as that which constitutes the material of said brick rammed into the spaces between adjacent courses and between the bricks of each course, said mix coalescing with said bricks to form a substantially integral monolithic structureof substantially uniform density throughout said bricks and the intervening mix.

7. The method of constructing a furnace bottom, which consists in laying a course of spaced bricks, ramming between them a, mix having substantially the same refractory characteristics as that of said bricks to attain a density of substantially the same order as that of said bricks, ramming a layer of similar mix upon said first course, in coalescing engagement with saidfirst mix, laying a second course of spaced bricks upon said rammed layer, and ramming between the brick of the second course a similar mix in coalescing engagement with the mix of said layer, to form an integral monolithic structure of brick and mix having substantially uniform density throughout.

8. A monolithic furnace bottom, comprising superimposed courses of refractory brick, the

fractory characteristics as that which constitutes the material of the brick of said uppermost course rammed into the spaces between adjacent courses and between the bricks of said uppermost course, said mix coalescing with said bricks to form a substantially integral monolithic structure in which the bricks of the uppermost course and the rammed mix are characterized by substantially the same density.

9. The method of constructing a furnace bottom of a plurality of brick courses, which consists in laying a course of spaced brick, ramming between said bricks a mix, and upon them a layer of mix in coalescing engagement with the first mix, laying a second course of spaced bricks upon said rammed layer, and a mix between and in a layer upon said last-mentioned bricks, the bricks of the uppermost course being of higher refractory characteristics than those of the lowermost course, and the mix when rammed being of substantially the same density and at least as high refractory characteristics as that of the adjacent bricks.

' FRED M. MILLER.