US2684842A - Refractory block for electric arc furnace lining - Google Patents

Description

July 27, 1954 cs. CRESPI ET AL REFRACTORY BLOCK FOR ELECTRIC ARC FURNACE LINING 1 Filed July 27, 1948 2 Sheets-Sheet l .1 fr m 9 w 44455240 (W) Aitorneys G. CRESPI ET AL I REFRACTORY BLOCK FOR ELECTRIC ARC FURNACE LINING Filed July 2'7, 1948 July 27, 1954 2 Sheets-Sheet 2 Inventors 6IESP/ s f 6414 5544A tlorneys Patented July 27, 1954 REFRACTORY BLOCK FOR ELECTRIC ARC FURNACE LINING Giovanni Crespi and Francesco Della Bella, Brescia, Italy; said Della Bella assignor to said Crespi Application July 27, 1948, Serial No. 40,966 Claims priority, application Italy August 1, 1947 3 Claims.

This invention relates to a refractory lining for a steel fusing furnace, and more particularly has reference to such a lining formed of refractory blocks provided with a reinforcing frame therein.

Heretofore, the Walls of electric arc furnaces for the fusion of steel were lined with refractory material by placing temporarily within the furnace to be lined, a plate element parallel to the walls of the furnace, and of such a size as to form, with said walls, an interstice in which a refractory material was pressed. Said refractory material was generally dolomite which, after the removal of the plate element, forms the desired lining.

Linings made in this manner must be renewed periodically and, generally, after about 90 to 100 melting operations. Therefore, the importance of the time required for the reconstruction of the lining, with regard to the running expenses of the furnace, is obvious.

The above method is rather laborious and requires that the furnace be inactive for a long time, even for as long as 20 hours. Besides this, even when the greatest care is taken, it is exceedingly difficult to obtain a lining which is uniform both with regard to compactness and resistance.

The lining can be formed in a much more rapid and easier manner, and better results with regard to its resisting and refractive properties can be obtained by following the teachings of the present invention.

According to the present invention, the lining is constructed by ranging against the walls of the furnace (which have previously been cleaned and freed from any roughness), starting from the floor of the furnace which has been remade or put in perfect order in its perimetrical parts, one or more lines of prefabricated blocks. These blocks are formed out of the furnace, by the compression of a dry and incoherent refractory mass, round a suitable framework in a mold corresponding to a segment of the final lining. In said refractory mass, rigid anchoring means such as pieces of iron-bar or -wire may be inserted into the block at various heights, or in suitable cementing means of the incoherent refractory material.

The blocks will, naturally, have a shape corresponding to that of the furnace in which they are placed, that is, they will be cylindrical if the furnace is cylindrical internally, or truncated cone segments, if they are to be used in a truncated cone section, etc.

The dimensions and shapes of the sections of the blocks are such that the blocks, when fixed in place, will be near one another, in which case the union takes place so as to leave between them a practically triangular shaped space which is filled with the same refractory material by pressing it in between the blocks.

The refractory material of which the blocks are composed may be made of powdered quartzite mixed with small quantities of lime and kaolin, for example 2 to 5% of lime and 3 to 8% of kaolin. It may consist of dolomite which may be entirely in powdered form or in the proportion of in powdered form and 40% in pieces of from 4 to 6 mm. in diameter; or dolomite mixed with magnesite in various percentages; or dolomite mixed with tar in the lower part and of pure dry dolomite in the remainder; or stabilized dolomite; or chromite with 8 to 12% of kaolin; or magnesite with 8 to 14% of kaolin and other refractory mixtures or substances.

When it is possible to shape this material in advance into bricks or briquettes, the blocks may be obtained by the complete pressed filling of the framework with these bricks or briquettes, even without the help of the shaping case or mold.

The molds and frameworks mentioned above may, in practice, be of many shapes, inasmuch as it is only essential for the former to be in the shape of the blocks having at least four lateral walls singly removable so as to enable the removal of the blocks after formation without damaging the same, and for the blocks to have a basic framework and implements of attachment connected to the same and abutting on the surface of any one face of the block for the purpose of transporting the same.

These characteristics will be made clearer by the description which follows with reference to the drawings which represent, in a non-limitative manner, the preferred shapes of the molds, of the frameworks and of the lining blocks which can be obtained with the same.

In the drawings:

Figure 1 is a diagrammatic perspective View of a cylindrical furnace after the placing in position of the lining blocks according to the inven tion;

Fig. 2 is a perspective view, on an enlarged scale, of one embodiment of the framework of the block;

Fig. 3 is a view similar to that shown in Fig. 2 of another embodiment of the framework;

Fig. 4 is a similar view to that of Fig. 2 of a third embodiment of framework;

Fig. 5 is a perspective view, on the same scale as Figs. 2 and 4 of one embodiment of the mold;

Figs. 6 and 7 are two partial horizontal sectional views respectively of the left and of the right half, of a lining consisting of two different shapes of blocks;

Figs. 8 and 9 are vertical sectional views of the various means of attachment of the lining of the walls with the floor of the furnace.

According to the drawings, the blocks I, having the shape of annular segments in section, are made in sheet metal molds'composed of a front wall 2, a back wall 3, and two side walls 1 and 5 attached to the front and back walls by means of bolts inserted in holes 6, of flanges I, at the edges of the various walls. This results in a mold which is easily taken apart. The walls are also provided with flanges 8 for the anchoring to the ground. After the introduction of a framework of the type shown in Figs. 2 to 4, in the mold, the refractory material chosen for the lining of the furnace is pressed. This framework is built, pref erably, of iron rods and must be included in the block.

It is composed of a base frame 9 which may be surrounded by a cage HI, conforming to the shape of the block as in Fig. .2, or by a light superstructure i i, ending in suspension hooks 12, as in Fig. 3, or it may be directly connected to these suspension hooks as in Fig. 4.

In order to free the block from the mold, it is sufiicient to remove the bolts inserted in the holes 5, and then to remove the four wall elements of the mold, after having disconnected the walls from the anchorages to the ground, if the mold has no base and the block is formed on the ground, as in the case shown.

In the furnace the various blocks, according to their section, may be close to one another (Fig. 6) or leave spaces 13 (Fig- '7), which are later filled with refractorymaterial which is pressed.

In the furnace, the finished lining has the appearance shown in Fig. 1, in which H indicates the external covering and IS the door of the furnace. The lining block placed in correspondence to the cast mouth has, in this spot, a wooden cylinder which is destroyed during the heating of the furnace, thus leaving the passage free for the passage of the metal.

As to the placing of the blocks 1, with regard to the floor l9, this may be as shown in Fig. 8 if the floor is slightly raised in its periinetrical sections 19 up to the level of the bath of molten metal or, as in Fig. 9, if the floor 39 is absolutely fiat. In the latter case, when the lining is completed with blocks 1, which are higher than in the former case, a concave lining 26 is placed on the floor.

It is understood that in practice, both the particulars of the process and those of the construction of the blocks may vary from those shown in the drawings and hereinbefore described, without departing from the scope of the present invention.

We claim:

1. A refractory lining for a steeel fusing furnace at least partially formed of prefabricated blocks of large size constituting each a section of the whole lining, and having the same form and the same thickness of the portion of the lining which they form, each of said blocks being composed of a bonded mass of incoherent refractory material and a reinforcing frame embedded in said mass, and being furthermore provided with grasping means for facilitating the transport thereof in the interior of the furnace.

2. A refractory lining according to claim 1 in which the refractory material constituting the blocks is bonded with tar.

3. A refractory lining according to claim 1 in which the spaces between the blocks are filled with pressed material of the same nature as the material constituting the blocks.

References Cited in the file of this patent UNITED STATES PATENTS Number Name I Date 540,465 Talbot June 1, 1895 1,268,929 Conniff June 11, 1918 1,649,313 Makowski Nov. 15, 1927 1,969,653 La Morte Aug. 7, 1934 1,983,589 Anderson Dec. 11, 1934 2,125,193 Morlock July 26, 1938 2,366,156 Simonson Jan. 2, 1945 2,427,401 Gillberg Sept. 16, 194'? 2,510,352 Sklemar June 6, 1950

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