US2480359A - Brick lining for molten metal containers and method of making the same - Google Patents

Description

Aug. 30, 1949. w. s. DEBENHAM 2,480,359

BRICK LINING FOR MOLTEN METAL CONTAINERS AND "ETHOD OF MAKING THE SAME Filed April 19, 1944 2 Sheets-Sheet l Eta- L INVENTOR. M104 5 flashy/M4 14 ar/lqy v Aug. 30, 1949. w. s. DEBENHAM 2,430,359

BRICK LINING FOR MOLTEN METAL CONTAINERS AND METHOD OF MAKING THE SAME Flled Apnl 19 1944 2 Sheets-Sheet 2 I IN V EN TOR. M4 L M .5. 0.650%;

,4 arm 1500 tons Patented a... so, 1949 BRICK LINING FOR. MOLTEN METAL GON- gAINERS AND METHOD OF MAKING THE Williams. Debenham, Chicago, 111., assignor to Carnegie-Illinois tion of New Jersey Steel Corporation, a corpora- Application April 19, 1944, Serial No. 531.802 8 Claims. (01. 2 3-46) This invention relates to brick linings for molten, metal containers and to a method of making the same. While not limited to hearths of blast furnaces, it is especially applicable thereto.

' In the m'ajority'of blast furnaces, the hearth is constructed of several courses of high heat duty fireclay tile, with the tile laid on end and the individual courses rotated so as to break all vertical joints at each course. These tile are 13 x 6" x 3", 18" x 9" x 4%", or even larger,

and possess typically the following physical and chemical properties:

Chemical analysis- Per cent A1203..- 38.00-42.00 S102 50.00-54.00 FezOa 1.00- 2.50 TiOz 1.00- 2.50 0:10 .20- 1.00 MgO .10- .50 Alkalies .20- 1.50

Pyrometric cone equivalent: (POE-Cone 32-33 Apparent porosity: PLO-18.0% True porosity: PLO-24.0% Bull: density: 1.20-1.30 oz./cu. in. Deformation under load of 25# per sq. in.: 7 Initial deformation, 2200-2300 F.-

Per cent deformation after 1% hours at 2462" F., 1.54.5%-

At the end of a typical blast furnace campaign of from 1,000,000 to 3,000,000 tons, it is found that a large portion of the solid hearth of firebrick has been displaced by iron. This iron-filled depression, or "salamander varies considerably in contour, but is generally in the shape of an inverted cone with the apex toward the bottom of the hearth, and may contain anywhere from 200 to of iron, which must either be tapped ofi while molten or blasted out after solidification, or both. before reconstruction of the furnace lining can be started. The formation of the salamander is the result of several factors. The fireclay brick are attacked and gradually eroded by the calcium silicate slag with which they come in contact at the end of each cast and this erosion is accelerated by the formation of an irregular surface. The'brick may actually be floated out due to the molten iron penetrating the brick joints. This penetration may be due to ,brick and mortar shrinkage, improperly filled or excessively large joints, or the greater susceptibility of the mortar to erosion. Those brick within one where temperatures exceed the approximate 2250" F. shown above as necessary to initial deformation under load, are compressed by the super-imposed loads of 20 to 50 pounds per square inch resulting from the weight of molten iron and blast pressure, so that the initial true porosity of the brick is reduced to practically zero, or inv other words, a volume reduction of approximately 20% occurs.

Examination of hearths that have completed a full campaign and of those in which hearth failures have caused premature shutdowns, indicate that all of the above conditions exist, but it is believed that the progressive penetration and subsequent widening of joints by molten iron is of primary importance in determining the 'flnal salamander size, whetheror not brick are floated out as a result of such action. For example, hearths of furnaces which have made less than 150,000 tons, have been found to contain vertical iron seams from one to over six inches in width and extending below the salamander proper as much as four or five feet. As such seams are invariably wider at the salamander and taper toward the bottom, they suggest that iron penetration occurs very early in the campaign, and that this penetration, once an entry has been made, is a continuous operation in which the iron progressively penetr 'es,

vitrifles and squeezes aside the brick, producing a sawtooth" effect that presents far more surface tothe eroding action of the slag, thus hastenfurnace hearth that will become monolithic with sufficient rapidity to eifectively. seal the joints against the initial penetration of iron.

after referring to the attached drawings, in Figure 1 shows an hearth; and Figure 2 shows an mixer with one construction of lining shown to the left of the center line and another construc tion shown to the right of the center line.

Referring more. particularly to the drawings, the reference numeral 2 indicates the concrete base of the hearth of a blast furnace. Supported on the hearth is a plurality of courses 4 of high refactory firebrick of the type disclosed above. The top course 6 is made of a low refractory firebrick of a type that will swell and become pyrofollowing specification and which This and other objects will be more apparent elevation of a blast furnace elevation of a hot metal plastic at comparatively low temperatures thus producing a monolithic hearth surface before molten iron has an opportunity to penetrate the joints. These brick are laid without mortar and bloat and swell when reheated above 2300 F. and when laid tight and subjected to load weld themselves together and to the underlying brick. The brick has the following chemical and physical properties:

Chemical analysis- Per cent A1203 22.00-27.00 SiOz 60.00-70.00 F8203 2.00- 5.00 TiO: .50- 1.00 CaO .40- 1.00 MgO .40- 1.00 Alkalies 2.50- 4.00

Pyrometric cone equivalent: (PCE)Cone 15-20 (2615-2786 F.) Apparent porosity: 10.00-14.00% Density: 1.30-1.35 oz./cu. in. Linear expansion on reheat to 2350 F.: 10.00-

25.00% Deformation under load of 25# per sq. in.

Initial deformation, 1900-2000 F. Per cent deformation when heated to 2300 It is not possible nor is it intended that the top course of brick 6 have any appreciable permanence. The usual slag action will take place and the layer will eventually disappear. However, this course of brick performs its function by softening and flowing plastically into all irregularities, joints and crevasses of the underlying high refractory brick, thus providing an effective seal against molten iron for a period suflicient to permit the high refractory and hence slower deforming brick to become compressed and monolithic themselves. Once this is achieved, the regular hearth will continue to erode smoothly since iron seams and their detrimental effects are eliminated.

Figure 2 discloses the invention applied to a hot metal mixer. The action of the hot metal on the firebrick lining is quite similar to that described above as typical of blast furnace hearths, the difference being primarily one of degree of severity since the temperature in the hot metal mixer is considerably less than in a blast furnace hearth. As shown in Figure 2, the shell 8 of the mixer is lined with two courses of high refractory firebrick l0. As shown to the left of the center line, the inner course of brick I2 is made of low refractory firebrick and is laid on'the inner course or high refractory brick. The construction to the right of the center line is the same as to the left except that the low refractory brick is bonded to the high refractory brick by means of grooves M on the inner course of high refractory brick which are formed by having alternate bricks of different heights. Alternate bricks l 6 in the low refractory course are of greater height than the remaining bricks and extend into the grooves l4. The low refractory firebrick linings in the hot metal mixer act in the same way as in the blast furnace to protect the high refractory firebrick.

While three embodiments of the invention have been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. A lining for furnace hearths and the like.

' comprising a top or irmer course of a dense low refractory, bloating type, firebrick and a lower.

or outer layer of high refractory firebrick.

2. A lining for furnace hearths and the like, comprising a top or inner course of dense low refractory firebrick which bloat when reheated to temperatures in excess of 2300 F. and which deform initially under load at temperatures below 2000 F., and a lower or outer course of high refractory firebrick which do not deform under load below 2000 F. or show greater than 2% linear change when reheated to 2550" F.

3. A method of conditioning refractory linings of furnace hearths or the like, which comprises, providing a top or inner course of a dense low refractory, bloating type, firebrick to prevent metal penetration of the brick joints and a lower or outer course of high refractory firebrick which constitutes the lining proper and which is protected from uneven wear by the low refractory brick.

4. A method of conditioning refractory linings of furnace hearths or the like, which comprises, providing a top or inner course of dense low refractory firebrick which bloat when reheated to temperatures in excess of 2300 F. and which deform initially under load at temperatures below 2000 F. to prevent metal penetration of the brick joints and a lower or outer course of high refractory firebrick which do not deform under load below 2000 F. or show greater than 2% linear change when reheated to 2550" F., said high refractory firebrick constituting the lining proper and being protected from uneven wear by supporting molten metal comprising an outer layer of high refractory firebrick constituting the lining proper, and a layer of a low refractory brick between the outer layer and the molten metal, which low refractory brick under furnace conditions will soften and become monolithic before molten metal can penetrate the joints and thereby protects the outer layer from metal penetration.

'7. The method of conditioning refractory linings of furnace hearths or the like, which comprises providing an outer course of high refractory firebrick which constitutes the lining proper, placing on the high refractory lining a layer of firebrick which is plastic at the operating temperature of the furnace, heating said layer to the operating temperature, applying a pressure thereto and continuing the application of the pressure until the permanent lining is transformed into a monolithic body.

8.. A method of conditioning refractory linings of a hot liquid metal container which comprises providing a permanent lining of high refractory firebrick, placing on the permanent lining a layer of refractory which is plastic at the operating temperature of the container, and placing hot liquid in the container.

WILLIAM S. DEBENHAM.

(References on following PIIO) 8 6 REFERENCES CITED Number Name Date The following references are or record in the ggg'gig g gzz g :82;

this patent 2,299,084 Ferngren Oct. 20, 1942 UNITED STATES PATENTS 5 OTHER REFERENCES g g Ma r Page 141 Blast Furnace Practice," vol. II, by

y Fred Clement, 1929, published by Ernest Benn, 1,940,115 Broadwell Dec. 19, 1933 Ltd London Bouvene House E c 4 2,186,223 I Wilkins-n--. Jan. 9, 1940 I 2,211,127 Keydel Aug. 19, 1949

Images