US3518330A - Method for prolonging the life of the cone section of the refractory lining of a basic oxygen furnace of the kaldo type - Google Patents

Description

June 30, 1970 R. J. DEMAISON 3,518,330

METHOD FOR PROLONGING THE LIFE OF THE CONE SECTION OF THE REFRACTORY LINING OF A BASIC OXYGEN FURNACE OF THE KALDO TYPE Original Filed Jan. 7, 1965 A TTOR'NE YS.

United States Patent O "ice 3,518,330 METHOD FOR PROLONGING THE LIFE OF THE CONE SECTION OF THE REFRACTORY LINING ggBASIC OXYGEN FURNACE OF THE KALDO Raymond J. Demaison, Mount Vernon, N.Y., assignor to Quigley Company, Inc., a corporation of New York Original application Jan. 7, 1965, Ser. No. 424,071, now Patent No. 3,351,460, dated Nov. 7, 1967. Divided and this application Aug. 28, 1967, Ser. No. 663,864

Int. Cl. F2711 1/16' U.S. Cl. 264-30 3 Claims ABSTRACT OF THE DISCLOSURE A method of repairing the refractory lining in the cone section of a steel producing basic oxygen furnace of the continuously rotating converter type while it is operating on an inclination and producing steel. Refractory slurry is sprayed onto the exposed and molten slag coated cone section to build up a composite coating of refractory material and slag.

This application is a division of copending application Ser. No. 424,071, filed Jan. 7, 1965, now Pat. No. 3,351,460.

This invention is directed to a method of maintaining against progressive deterioration the flame exposed refractory surface of the cone section of a Kaldo basic oxygen furnace while it is rotating and producing steel therein.

In this type of furnace, the CO and CO normally developed in the furnace during operation is actually burned inside the furnace. The Kaldo furnace was developed by Professor Bo Kolling and his associates and placed in full scale operation in May 1965 at Domvared, Sweden. It consists of a rotating concentric cylindrical furnace inclined at 17 (degrees) from the horizontal so that the melt will cover at least half of the back wall, and it is rotated at speeds up to 35 rpm. The angle of inclination increases the productive capacity of the furnace and exposes more of the lining to the cooling effect of the mass of metal during rotation. The high speed of rotation provides a greater degree of slag to metal contact than does a stationary converter and the slag is formed earlier therein than in other processes to result in the rapid elimination of phosphorous and at the same time result in a low loss of iron in the slag.

In the normal operation of the furnace with no spraying, two cone linings to one body lining are required with the necessity of shutting the furnace down to replace the cone lining only. By the use of the instant method of spraying, the cone lining life may be extended beyond the life of the body lining and thus obviate the necessity of a shutdown for relining of the cone.

The spraying operation can be accomplished by inserting a shooting pipe into the furnace between the hood and the furnace mouth or through a hole in the hood while the steel contained therein is being blown with oxygen and while the furnace is rotating, the refractory material being sprayed onto the cone lining over the slag on the emerging hot face of the lining. The refractory material is thus subjected to the maximum heat in the furnace as the furnace continues to rotate and is then washed over by the molten slag and the molten metal contained in said furnace.

In the accompanying drawings:

The single figure is a cross sectional view of a basic oxygen furnace of the Kaldo type and clearly shows the various positions assumed by the furnace during the operational cycle. I

Patented June 30, 1970 The hot metal and scrap loading position is shown at 51, the blowing and lime and ore adding position at 52, and the pouring position at 53. It must be remembered that in the Kaldo process the furnace 50 is rotated about its axis and hence a more even wear pattern is established on the surface of the refractory lining. The mouth of the furnace is fitted with a water-cooled hood swingably mounted with the water-cooled oxygen lance 22 and watercooled jacket 55 and the lime and air charging means 54 mounted therein. The cone section 60 of the furnace is coated with protective refractory material while the furnace is in operation by means of a stiff spray pipe 57 and a lateral nozzle 59 which can be inserted between the hood and the furnace mouth, using a shield 42 to protect the operator. The nozzle will be moved back and forth to direct the stream of material over the entire face of the cone section 60. A flexible supply hose 58 leading from any suitable source, is connected to the spray pipe 57.

The refractory material used for the repair and coating of the furnace linings may be of any type so long as it is suitable and effective for the practice of the invention as herein described. However, reference is made to the three following patents owned by the assignee of the instant application as examples of suitable refractory materials: No. 2,809,126, dated Oct. 8, 1957, wherein the coating composition consists primarily of chrome ore; No. 3,093,496, dated June 11, 1963, wherein the coating composition consists of a mixture of chrome ore and magnesia but wherein the chrome ore predominates; and No. 3,093,497, dated June 11, 1963, wherein the coating composition consists of a mixture of chrome ore and magnesia but wherein the magnesia predominates. Reference is also made to Pat. 3,093,458, dated June 11, 1963, also owned by the assignee of the instant application, and wherein refractory compositions of different refractoriness are employed in building up a multiple layer coating.

Another refractory material which may be used for the repair and coating of the furnace linings is disclosed in the copending Dreyling et al. application Ser. No. 173,839, filed Feb. 16, 1962, which material consists essentially of dead burned or fused magnesite containing certain binding and barrier materials.

Different types of spraying apparatus may be employed in carrying out the process and reference is made to the following patents all owned by the assignee of the instant application: No. 2,700,535, dated Jan. 25, 1955; No. 2,997,244, dated Aug. 22, 1961; and No. 3,114,536, dated Dec. 17, 1963.

Reference is also made to the following copending applications which also disclose further types of spraying apparatus that may be used in carrying out the instant process: Demaison application Ser. No. 319,001, filed Oct. 25, 1963; Demaison application Ser. No. 383,416, filed July 17, 1964; and Demaison application Ser. No. 402,203, filed Oct. 7, 1964.

What is claimed is:

1. A method of prolonging the life of the cone section of the refractory lining of a steel producing basic oxygen furnace of the continuously rotating converter type arranged at an inclination such that a portion of the cone section will be immersed in the furnace molten charge during the steel producing operation of the furnace, said furnace molten charge consisting of a molten steel bath and a molten slag layer floating thereon, which method comprises the step of forming upon the surface of the cone section successive protective refractory coatings by spraying a wet slurry of refractory material upon the exposed or unimmersed surface of the cone section as it rotates continuously during a steel producing operation of the furnace, thereby subjecting the sprayed-on refractory material to the maximum heat of the furnace atmosphere during those periods when the cone section is exposed or unimmersed in the furnace molten charge and thus subject to erosion and spalling and also to the direct heat of the molten steel bath during those periods when the cone surface is immersed in said bath.

2. A method according to claim 1, wherein the spraying operations are performed by insertin into the furnace through the mouth thereof a rigid spray pipe pro vided with a discharge nozzle which is manipulated to distribute the refractory material onto the exposed or unimmersed surface of the cone section during a steel producing operation of the furnace.

3. A method according to claim 1, wherein the refractory material is sprayed onto the exposed or unimmersed surface of the cone section and caused to adhere to any molten slag adhering to the cone surface as a result of the rotation of the furnace with reference to the furnace molten charge, thereby forming a composite refractory coating.

References Cited UNITED STATES PATENTS 2,700,535 1/ 1955 Harrington et al 259-151 3,093,458 6/1963 Demaison 264-256 3,114,536 12/1963 Demaison 259-151 3,241,987 3/ 1966 Dreyling et a1 106-58 3,351,289 11/1967 Demaison 264-30 3,351,460 11/1967 Demaison 75-60 3,355,528 11/1967 Henry 264-30 3,396,855 8/1968 Demaison 264-30 2,809,126 10/1957 Murphy et a1. 264-30 3,093,496 6/1963 Demaison et a1. 106-59 3,093,497 6/1963 Demaison 106-59 DONALD J. ARNIOLD, Primary Examiner J. H. MILLER, Assistant Examiner

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