US2894739A

US2894739A - Ladle relining method

Info

Publication number: US2894739A
Application number: US555590A
Authority: US
Inventors: Donald B Spencer
Original assignee: Guy F Atkinson Co
Current assignee: Guy F Atkinson Co
Priority date: 1955-12-27
Filing date: 1955-12-27
Publication date: 1959-07-14
Anticipated expiration: 1976-07-14

Description

Filed Dec. 27, 1955 D. B. SPENCER LADLE RELINING METHOD 2 Sheets-Sheet 1 INVENTOR.

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July 14, 1959 D. B. SPENCER LADLE RELINING METHOD 2 Sheets-Sheet 2 Filed Dec. 27, 1955 R Z En e mp 5 B 2 n O D United States Patent LADLE 'RELINING METHOD Donald B. Spencer, Portland, Oreg., assignor t'o Guy F. Atkinson Company, South San Francisco, Calif., a corporation of Nevada Application December 27, 1955, Serial No. 555,590

3 Claims. (Cl. 26643) This invention relates generally to methods and apparatus for repairing the inner refractory linings of ladles and the like, such as are used in handling molten metal.

Ladles such as are used for transporting molten metal from a furnace to molds or other apparatus are lined with a refractory material, such as firebrick or the like. Generally the lining is of considerable thickness to prop erly protect and insulate the outer metal casing of the ladle. Various factors, including the high temperatures and the impact of the molten metal when it is poured into the ladle, cause progressive disintegration of the lining, particularly in the lower portion of the ladle where the bottom and adjacent side walls of the lining become worn away. The lining must be repaired before it has been disintegrated to a sufficient extent to endanger the outer casing.

In the past such repair operations have been expensive and time consuming. One repair method that has been used involves taking the ladle out of service and permitting it to cool to a sufficiently low temperature to permit workmen to enter. In a typical instance this may require a cooling period of from 20 to 40 hours, depending upon the size of the ladle. Thereafter worn portions are removed and new refractory applied. Assuming the use of mortar or like wet mixes and firebrick, the repaired portion must be cured before the ladle is returned to service. It will be evident that this procedure is expensive and time consuming, and has a number of disadvantageous features. In addition to the addition to the amount of time required, which may vary depending upon the magnitude of the repair, the conventionalprocedure just described involves an undesirable heat loss. It may be explained that in normal practice where the ladle is being used with a smelting furnace, the lining retains considerable heat between successive filling and pouring operations. By way of example, the lining may remain at temperatures of the order of 2600 to 2800 F., and the metal shell at about 150 F.

Another ladle repair method that has been applied to some extent involves use of slag to fill spaces left by lining wear or disintegration. By way of example the ladle is placed in a holder at an angle of about 45 to the vertical and then slowly rotated about its axis. A measured quantity of molten slag, derived from the smelting operation, is introduced into the ladle, and rotation continued to cause progressive solidification or freezing of the slag to fill the worn spaces. While the amount of time required is not as great as with the first described method, the ladle is then out of use for a matter of hours, during which time considerable heat loss again occurs. It has been found that the useful life of such a repair is relatively short, due to various factors, including lack of a regular predetermined form to the solidified slag.

It is a primary object of the present invention to pro- 2 vide an improved method and apparatus for repairing the inner refractory linings of ladles.

Another object is to provide a novel method and apparatus of the above character which will permit such repair operations without substantial loss of heat.

Another object of the invention is to provide a method and apparatus of the above character which will provide a lining repair having a relatively long useful life.

Another object of the invention is to provide a novel apparatus for carrying out the present method, and which makes possible a lining molding operating in situ-within the ladle, to a desired contour.

Additional objects and advantages will become apparent from the following description taken in connection with the accompanying drawings which illustrate a preferred form of the invention. It is to be understood however that the invention may taken other forms and that all such modifications and variations within the scope of the appended claims, which will occur to persons skilled in the art, are included in the invention.

Referring to the drawing:

Figure l is a vertical sectional view of the ladle with the present repair apparatus applied thereto, taken on the line 1-1 of Figure 2.

Figure 2 is a top plan view of the ladle and repair apparatus. 7

Figure 3 is an elevational view of a slightly modified form of mold.

My method can be best understood after a description of the apparatus illustrated in the drawings. Figure 1 illustrates a ladle 10 of a conventional construction, and is such as is used in smelting and refining operations for carrying molten metal from the smelter or furnace to other apparatus or to molds. In accordance with conventional practice the ladle is shown provided with pouring spouts 11 by means of which metal is discharged when the ladle is tilted. The outer housing or casing 12 is formed of suitable metal, such as steel. The inner refractory lining 14 is indicated as being formed of refractory firebrick. While the form may vary in this instance the inner surface of the lining is annular in horizontal section. The bottom and lower walls of the lining, where it is particularly subject to wear, may be somewhat thicker than the upper lining portions, as indicated by the dotted contour line 15. After repeated use the wearing away of the lining may be such as to remove material to the contour line 16.

The apparatus which I employ for carrying out the present method consists in general of a molding assembly 20, together with frame means 21 for supporting the assembly in a predetermined position during a lining repair operation. The supporting frame 21 consists in this instance of radially extending arms 22 having their outer ends adapted to be seated on the upper edge of the ladle. The outer end of each arm may be provided with a depending guide lug 24, to center the supporting means with respect to the vertical center line of the ladle. The inner ends of the arms are secured to the vertical central sleeve or hub 26.

The mold assembly 20 consists of a hollow stem or a neck portion 27 which slidably interfits the sleeve 26. A hollow mold or chill form 28 is attached to the lower end of stem 27. This mold can be formed of cast steel or like metal, and may be constructed in two cup shaped sections welded together at 29. In Figure 1 the shape of the mold is spheroidal, although as will presently be explained the shaping may vary in difierent instances depending upon the contour desired for the repaired lining.

A pipe 31 is shown extending down into the mold 28 for introducing a cooling liquid, such as water. An other pipe 32 is shown for discharging hot water and/or steam. Suitable means is provided for delivering water to pipe 31 and receiving water and/or steam discharged from pipe 32. For example a hose may connect pipe 31 to a valve controlled source of water under pressure, and a hose may connect pipe 32 to a sump.

Closures

33 and 34 are shown for the upper and lower ends of the stem.

Downward movement of the stem 27 within the sleeve 26 is limited by suitable means such as the collar 36, which is attached to the upper end of the stem. The bolt serving to attach this collar to the stem may be optionally applied through holes provided at various levels in the stem, whereby the assembly can be supported at any level desired. A hook or bale 37 is attached to the upper end of the stem and is adapted to be engaged by a crane or other hoisting means, whereby the entire apparatus can be raised or lowered as desired.

The mold 28 and associated parts should have sufiicient weight when filled with water to displace the molten slag, and to bring the collar 31 to rest upon the upper end of sleeve 26. By way of example the weight of the mold and associated parts, when filled with water, may be about twice that of the displaced slag.

Operation of the apparatus described above, and the carrying out of the present method, is as follows: The mold 28 is filled with water, and the apparatus is held in readiness adjacent the ladle, with the bale 37 being suspended by a crane or other hoisting means. Because of the slidable relationship between the stem 27 and the sleeve 26, the stem and the mold are at that time in a 9 raised position with respect to the frame 21. A measured batch of molten refractory material is made available for use as a lining. This material should be compatible with the material used for the original lining, and when solidified it should form a refractory having the desired heat insulating and disintegration resisting properties. The melting point can be somewhat lower than the refractory material used in the original lining, and it should not be subject to excessive shrinkage upon cooling. A suitable material for this purpose is molten mill slag obtained as a lay-product in the smelting of metals. Such a slag may consist largely of silicates and oxides. It is desirable to employ the slag produced in the ore smelting operation with which the ladle is being employed, particularly because such slag is generally suitable and is conveniently available in molten form. For example good results have been obtained by employing slag produced from the smelting of nickel ore, where the ladle is being used with such an operation.

Assuming that a suitable molten slag is available. a

measured amount is poured into the ladle, and immediately thereafter my apparatus is lowered upon the ladle, whereby the arms 22 are first seated upon the upper edge of the ladle. and thereafter the mold 28 lowered to the final position shown in Figure 1. while maintaining circulation of cooling water. The molten material indicated at 41 in Figure l, is displaced to a level such as is indicated in this view. and it is rapidly cooled by transfer of heat to the mold. to effect its solidification. Thereafter the mold is raised free of the molded refractory, and the entire apparatus removed from the ladle.

It will be evident that the foregoing method provides a simple and inexpensive procedure for the repair of worn refractory lining. The procedure obviates the necessity of removing any part of the original lining, as in prior repair methods. The new portion of the lining is in effect molded in situ within the original lining. Assuming the use of. a proper refractory material the lining is restored to its original usefulness. It is not necessary to subject the ladle to preliminary cooling before carry ing out a repair as described above. Furthermore the entire operation requires only a matter of minutes, and may for example be completed in. as little time as six to ten minutes. This avoids loss of heat in the lining, ith t e resultant disadvantages previously mentioned.

Furthermore no material loss of heat occurs during the making of the repair, because of the relatively small amount of time required, and because of the heat contained in the refractory material. In this connection it may be noted that cooling of the mold to solidify the added refractory merely reduces the temperature of the slag to that required for solidification, and does not remove any substantial amount of heat from the lining. The repaired ladle can he put back into service immediately.

A repair made by my method has a long useful life, as distinguished from prior methods where slag is employed. For example repairs made by my method have been used in from 40 to 60 operations, Whereas the prior slag method previously described lasted for only about five or six operations. I attribute this to the fact that in my method the refractory is molded to predetermined form, and to the absence of heat loss.

By application of the foregoing method a lining can be repaired a number of times, before complete restoration of the original lining is necessary.

It will be evident that the invention is susceptible of various changes or of modifications, within the spirit of the present invention. For example the mold 28 can be shaped in various ways depending upon the lining contour desired. By way of example, in Figure 3 the modified mold 28 is provided with a tapered lower portion 42 and a fiat bottom portion 43. It will be evident that this type of mold forms a ladle lining having a fiat bottom. In both Figure 1 and Figure 3 the mold is upwardly divergent, to facilitate proper draw and easy removal from the solidified refractory.

While in the foregoing description the mold is arranged to move vertically with respect to the ladle, and is lowered into final position after the molten refractory has been introduced into the liner, it will be evident that in some instances the mold may be held in a predetermined position and the molten refractory introduced into the space between the mold and the original liner.

I claim:

1. A method for repairing a worn refractory lining of a ladle comprising introducing a quantity of molten refractory material into the ladle, molding the molten refractory material to a desired inner contour in situ around a rigid molding form between the inner surface of the worn ladle lining and the rigid molding form, and chilling the inner molded surface of the molten refractory material so as to solidify the same by directly cooling said molten refractory material substantially only from the inner surface thereof.

2. A method for repairing a worn interior refractory lining of a ladle for molten metal having a bottom wall connected to an upwardly extending side wall with an opening extending across the top of the ladle, comprising inserting a hollow rigid mold into the ladle in spaced relation to said lining, introducing molten refractory material into the ladle in sufiicient quantity to cover the worn portion of said lining around said mold, and supplying a cooling medium to the interior of the mold to cool directly the molten refractory material substantially only from the inner surface thereof to solidify the molten refractory material without substantial loss of heat from the ladle and its refractory lining.

3. A method for repairing a worn interior refractory lining of a ladle having a bottom connected to a side wall with an opening extending across the top of the ladle, comprising depositing a quantity of molten refractory material into the ladle, inserting a substantially rigid mold into the ladle for molding the molten refractory material to a desired inner contour around said rigid mold between the inner surface material of the worn ladle lining and the rigid mold, and applying a cooling medium to the mold so as to start solidification of the molten refractory material by directly cooling the same through its molded surface in contact with the rigid mold without substantial loss of heat from the ladle and its refractory lining.

References Cited in the file of this patent UNITED STATES PATENTS Presbney Apr. 24, 1866 Pedder Apr. 5, 1881 Mount Sept. 10, 1901 Veitch July 30, 1907