WO1997038140A1

WO1997038140A1 - Refractory liner and lining method for a vertical shaft metallurgical vessel

Info

Publication number: WO1997038140A1
Application number: PCT/US1997/005529
Authority: WO
Inventors: Ronald G. Brenneman; Douglas K. Doza
Original assignee: Allied Mineral Products LLC
Current assignee: Allied Mineral Products LLC
Priority date: 1996-04-04
Filing date: 1997-04-04
Publication date: 1997-10-16
Anticipated expiration: 1998-10-04
Also published as: DE19780414T1; MX9709437A

Abstract

A liner (32) and lining method for a vertical shaft metallurgical vessel (30). The liner (32) includes a working lining (50) within the shell of the vessel (38) and a secondary lining (42) exhibiting fluid properties, such as a dry-vibratable refractory lining, between the shell (38) and a portion of the working lining (50). The lining method includes the steps of providing a working lining (50) within the shell (38) of the vessel (30) and providing a secondary fluid refractory lining (42) such as a dry-vibratable refractory lining between the shell (38) and a portion of the working lining (50). The secondary lining (42) provides as a barrier to any molten metal and slag that may penetrate through the working lining (50) and may assist in prolonging the operating life of the working lining (50).

Description

REFRACTORY LINER AND LINING METHOD FOR A VERTICAL SHAFT METALLURGICAL VESSEL

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to a refractory liner and lining method for a vertical shaft metallurgical vessel, such as a hot blast cupola. The liner and lining method is advantageous

for many types of vertical shaft vessels, but offers special advantages for "dry-bottom"

cupolas and for the hearths (wells) of so-called "liningless" cupolas.

A hot blast cupola is a type of vertical cylindrical shaft furnace that normally is used

for the production of molten iron. The molten iron typically is used for making iron castings

in foundries; however, it also can be used in the production of steel. A cupola produces iron

by melting iron and steel scrap. The primary source of energy for melting the scrap charge is

supplied by the combustion of carbon (in the form of coke) with oxygen (from preheated pressurized air introduced into the furnace).

A cupola is a "counterflow" shaft furnace. The metallic scrap iron and coke fuel

normally are introduced from the top of the shaft and descend to the bottom. Meanwhile, the

preheated air ("hot blast") is introduced in the lower part of the shaft through a number of

nozzles (called "tuyeres") arranged around the periphery of the shaft. The combustion of the

hot blast with coke produces heat and gases that flow up the shaft, transferring heat to the

coke and metallic scrap. As the descending scrap approaches the combustion zone (at the melt and become liquid slag. The liquid iron and slag accumulate at the bottom of the shaft in

an area called the hearth or well. From here, the liquid iron and slag, at a temperature of about 2500 °F. to 2700 °F., flow out of the furnace through a tap hole. Cupolas typically have a tap

hole located in a side wall of the hearth for discharging the iron and slag from the hearth.

The iron and slag, in their liquid states, can be separated by flotation because of the

difference in their specific gravities. This separation takes place in a separator, siphon box or

other device constructed for this purpose. The separator may be connected to the cupola or

located apart from the cupola. After the iron has been separated from the slag, it is

transported to its end use through refractory-lined channels (called "launders") and transport

vessels (called "ladles"). The slag is cooled and disposed of or recycled for various uses.

To contain the heat, gases and molten metal and slag in a cupola and its associated

separators and to protect the structures of these units, specialized refractory materials in the

form of bricks, blocks, ramming masses, refractory plastics and refractory castables typically

are used, either alone or in combination with air and water cooling of the cupola structures.

The cupola hearth (i.e., the portion of the cupola below the tuyere level) typically has a

structural steel shell. (Unless otherwise specified, the term "hearth" includes any associated

slag separators, whether or not the separators are integral with the cupola, and the transition

areas between the hearth and the slag separators.) The shell is lined with a refractory to

maintain the steel shell below its maximum operating temperature limits and to contain the

molten metal and slag produced during the operation of the cupola. The refractory liner of the shell is a consumable material that is eroded or otherwise

damaged by exposure to the conditions within the cupola. When a certain amount of

consumption or damage to the liner has occurred, the operation of the cupola must be halted —

sometimes for an extended time ~ in order to repair or replace the refractory liner. The

frequency of these interruptions is determined by the consumption rate of the refractory liner

by the process. The duration of these interruptions is dependent on the consumption rate and

whether it is possible to repair localized damage to the liner without removing the undamaged

portions and replacing the entire liner.

Conventional refractory liners for cupola hearths typically consist of various

combinations of refractory bricks, blocks, and refractory specialty materials, such as

refractory plastics and refractory ramming mixes. These materials may have a relatively short

life (high consumption rate) and may require removal and replacement of the entire liner when

only a portion of the liner is eroded or damaged. This increases the cost of repair and greatly

increases downtime.

These materials also are prone to crack formation. Some cracks that form can extend

completely through the liner from the hot face (molten metal side) to the cold face (steel shell

side). When cracks of this nature occur during the operation of a cupola, the possibility of

molten metal and/or slag penetrating via these cracks to the cupola steel shell exists. When

this occurs, the molten materials can burn through the shell, resulting in the danger of

extensive damage to equipment and/or injury to personnel. A burn-through of this type can cause long, unscheduled delays in the operation to make repairs to the liner, steel shell and

structure, and any surrounding equipment.

Advances in refractory technology have produced new and improved refractory

materials that potentially offer advantages of longer life (lower consumption rate) and lower

operating and maintenance costs when compared to the prior liner designs. Foremost in these

technological advancements have been developments in refractory castable products. These

include low-moisture, low-cement, ultra-low cement, and no-cement castables. These

materials offer the potential for longer life and easier, faster, less expensive installations and

maintenance when compared to lining materials typically applied. For example, damaged

portions of castable liners generally can be repaired without removal and replacement of the

entire liner.

Unfortunately, castable refractories, like conventional lining materials, generally are

prone to crack formation. Some cracks that form in castable refractories can extend

completely through the cast body from the hot face to the cold face, resulting in the risk of

burn-through of the steel shell. Such lining failure may result in considerable damage and

production delays during repair of the damage. The tendency of castable refractories to form

cracks has been a major factor preventing widespread adaptation of technically advanced

castable refractories in cupola liners.

In view of the disadvantage of the prior art, a need exists for a cupola liner and lining

method that offers the advantages of a castable liner, has excellent resistance to crack

propagation and is easy to repair. This invention employs the unique characteristics of a refractory that exhibits fluid

properties, such as a dry-vibratable refractory. The fluid refractory is installed as a layer

surrounding all or part of a working lining of a cupola hearth, a slag separator, and/or the

transition area between them. This secondary lining layer reduces the risk of molten materials

contacting the shell of any of these units.

Dry-vibratable refractory is a preferred fluid refractory because it has excellent

resistance to crack propagation and is easy to repair. The characteristics of dry-vibratable

refractory enable it to form a barrier to any molten metal and slag that penetrates through the

working lining. As described further below, the characteristics of dry-vibratable material also

may contribute to extending the operating life of the working lining.

Dry-vibratable refractory exists in situ as an unbonded monolithic material. In this

unbonded state, it lacks the brittle behavior characteristic of formed refractories, and

therefore, tends not to form cracks or voids when subjected to external stresses under normal

operating conditions. The unbonded dry-vibratable material is able to absorb and distribute

local stresses without formation of cracks, as is typical with brittle refractories.

The chemical and mineralogical composition of dry-vibratable refractories can be

chosen to be resistant to the specific types and temperatures of metals and slags inherent to

each process, and can be designed to form strong ceramic bonds in predetermined temperature

ranges and at controlled rates of formation. When ceramic bonding of properly selected

dry-vibratable refractories occurs in this manner, the bonded portion of the material becomes 6 dense and hard. The bonded dry-vibratable material is chemically and physically resistant to

penetration of both molten metal and slag.

Meanwhile, the portion of the dry-vibratable layer that remains below the critical

temperature for the formation of ceramic bonding remains as an unbonded monolithic and

does not exhibit brittle behavior or cracking tendencies. In this manner, the bond formation is

progressive in nature and is influenced by time, temperature, and atmosphere.

The unbonded dry-vibratable material exhibits fluid properties. Thus, the dry-

vibratable material may protect the structural elements of the cupola from expansion of the

rigid refractory when it is heated and assist in isolating the rigid lining from mechanical

stresses. Dry-vibratable material also is relatively insulating compared to rigid refractories of the same mineralogical makeup. A dry-vibratable secondary lining insulates the working

lining, reducing the thermal gradient across the working lining. These properties of the dry-

vibratable lining may reduce stresses in the rigid, brittle working lining that may lead to

cracking or surface spalling. The reduction of these stresses may extend the operating life of

the working lining.

These and further objects of the invention will become apparent from the following

detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away partial side view of a dry-bottom, water-cooled cupola.

FIG. 2 is a sectional view of a slag separator of a dry-bottom cupola.

FIG. 3 is a side sectional view of the liner of the present invention installed in portions

of the hearth and slag separators of a dry-bottom cupola.

FIG. 4 is a top sectional view of the liner of FIG. 3.

FIG. 5 is a detail view of a portion of the liner of FIG. 4

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The liner of the present invention is used in the shell of a vertical shaft metallurgical

vessel to contain the molten metal and slag produced during the operation of the vessel. The

liner includes a working lining within the shell of the vessel and a secondary fluid refractory

lining between the shell and the working lining. The secondary lining provides an additional

barrier to the passage of any molten metal and slag that penetrates through the working lining.

Preferably, the fluid refractory lining is a dry-vibratable refractory. However, the invention

also contemplates the use of other fluid refractory linings.

The invention will be described with particular reference to a hot blast cupola vertical

shaft furnace used for melting iron; however, it also may be used to advantage in other types

of vertical shaft vessels. FIG. 1 shows a dry-bottom, water-cooled cupola 10. The cupola

includes a vertical shaft 12 with a water-cooling system 14. Scrap iron and steel and coke fuel

are introduced into the top of the shaft through charge door 16. Preheated air ("hot blast") is introduced in the lower part of the shaft through tuyeres 18. In some cupolas, oxygen may

also be injected through the tuyeres. Plasma torches may be used to further increase cupola

operating capacities.

The cupola includes a hearth 20 at the bottom of the shaft 12, below the level of the

tuyeres 18. The hearth 20 has a refractory lining 22. The cupola of FIG. 1 may be referred to

as a "liningless" cupola because the refractory lining 22 does not extend above the tuyere

level. The molten iron and slag accumulate in the hearth 20 before flowing out of the furnace

through a tap hole 24, shown in FIG. 2. FIG. 2 shows a slag separator 26 attached to a dry-

bottom cupola. A transition area 28 separates the tap hole 24 from the separator 26.

The secondary liner may be provided in a new cupola (whether or not the cupola has been designed to accommodate a fluid secondary lining) or during the replacement or repair of

the working liner of an existing cupola. It may be installed as a layer between the shell and all

or part of the working lining of the hearth, the slag separator, and/or the transition area

between them. To maximize the benefit of this invention, the secondary (dry-vibratable)

lining layer preferably will surround as much of the working lining as is practical in all areas

below the maximum molten metal and slag pooling level, during all phases of operation. In

the case of a dry-bottom cupola, this includes the bottom and sides of the hearth (well), the

attached or adjacent separator(s), and the transition between the cupola hearth and the body of

the separators). However, the secondary liner also may be installed adjacent to only a portion

of the working liner of one or more of these units to protect the shell in an area where consumption of the working lining historically has been high or where such consumption is

predicted to be high.

FIG. 3 shows the liner of the present invention installed in a dry bottom, hot blast

cupola 30. The cupola 30 includes a hearth 32 having a bottom 34 and sides 36 defined by a

shell 38. Two slag separators 39 are attached to the hearth 32. A transition area 40 extends

between the hearth 32 and each of the slag separators. The dry-vibratable material 42 may be

installed in a portion of the bottom 34 of the hearth, a portion of the walls 36 of the furnace, or, as shown in FIG. 3, a portion of both the bottom 34 and the walls 36. The dry-vibratable

material is installed in the hearth bottom 34 using conventional techniques, such as those

recommended by the manufacturer of the dry-vibratable refractory.

Conventional installation techniques for dry-vibratable materials are not readily

adaptable to installation of the wall portions 42A of the dry-vibratable liner 42 in a hot blast

cupola of an existing design. Thus, a new installation method was required to install the dry-

vibratable secondary lining in the walls 36 of the hot blast cupola 30. This new method

includes the use of retainer 44 (best shown in FIGS. 4 and 5) to hold the dry-vibratable

material 42 in position adjacent to the shell wall 36 during installation of the dry-vibratable material. The retainers 44 are installed around the periphery of the steel shell 38 at a

predetermined distance from the shell wall 36 (including any liner components attached to the

shell). In a normally cylindrical cupola, such as the cupola 30 of FIG. 4, the retainers may

define an annular ring (or an arc thereof) within the cupola shell 38. The retainers 44 and the shell wall 36 define a void of the desired thickness of the dry-vibratable layer to be installed along the wall of the shell.

The retainers 44 may take the form of shapes, such as thin (typically about 1 ^lΛ -3

inches thick) flat or curved plates made from refractory castable. Retainers of other designs or

compositions, such as refractory bricks or blocks, also could be used, provided that they

perform the function of holding the dry-vibratable material in a desired position during

installation and their composition is compatible with the cupola lining. When precast shapes

are used, they are placed over the layer of dry-vibratable material or other liner material

installed over the bottom of the shell. A spacer or clip may be provided between the top of

the precast shape and the corresponding portion of the shell wall to assist in maintaining the

shape in a desired position relative to the shell wall.

After the retainers 44 are placed in position, a sealing layer 46 (shown in FIG. 3) may be provided on the top of the dry-vibratable layer 42 on the bottom 34 of the shell to protect

the dry-vibratable layer from mechanical damage and contamination during forming and

casting. The sealing layer 46 may be provided over the entire dry-vibratable bottom layer 42

or over selected portions of this layer. Preferably, the sealing layer is formed from a layer of

ramming or plastic refractory material. However, the sealing layer also may be formed by

other suitable methods, including, but not limited to, providing a layer of castable refractory

material, applying heat to the upper surface of the dry-vibratable layer, or spraying a sealing

liquid, such as sodium silicate, over the dry-vibratable layer. Typically, a sealing layer of

ramming material in a full-size cupola will in the range of about 1 -2 inches thick; however, 11 the thickness may vary with the cupola size and conditions and the material used to form the

sealing layer. Use of a layer of ramming refractory or similar material as the sealing layer is

preferred when retainer shapes are used because this material provides the further benefit of

assisting in securing the retainers in their proper positions during installation of the dry-

vibratable material along the shell wall.

When the retainers 44 have been installed and any sealing layer 46 has been provided,

the space formed between the retainers 44 and the shell wall 36 is filled with dry-vibratable refractory 42A using conventional installation methods for such spaces. When the installation

of the dry-vibratable material in this space is complete, the top of the dry-vibratable wall

material 42A may be covered with a layer of a compatible refractory material 48, such as

ramming material, to seal the dry-vibratable layer and protect it from damage during

installation of the remainder of the liner.

The steel shell 38 of the cupola may include perforations (not shown in the drawings)

spaced at intervals over the bottom and walls to allow water and gases in the lining materials

to escape when these materials are dried and heated. These perforations typically are large

enough to allow dry-vibratable refractory to pass through them. The liner therefore may

include a heat-resistant, moisture permeable web 49 (shown in FIG. 5) between the shell, or at

least the perforated portions of the shell, and the dry-vibratable layer. The web 49 confines

the dry-vibratable refractory within the shell while allowing moisture to escape through the

perforations when the lining materials are heated. The web preferably is a woven high-

temperature fabric made from a spun refractory fabric, although other materials with similar properties also may be used.

When the secondary liner 42 has been installed, the installation of the remainder of the

cupola liner (referred to as the "working lining") may proceed. In the liner of the present

invention, the working lining 50 is spaced at a distance from the shell 38, and extends over the

bottom 34 and at least a portion of the walls 36 of the shell 38. Preferably, the working lining

50 is a castable refractory. However, other materials, such a carbon block or ramming

refractory, also could be used to form all or part of the working lining.

Similarly, the liner of the present invention may be installed in a bottom or wall portion of a slag separator 39, or the bottom or wall portion of the transition area 40.

Preferably, the lining extends continuously from the hearth 32 through the transition area 40

to the slag separator 39. However, the lining also may be installed separately in any one or

more of these units.

The method of lining the cupola shell 38 includes the steps of:

A. Providing a working lining 50 within the shell 38 that extends over the bottom 34 and

at least a portion of the walls 36 of the shell; and

B. Providing a secondary lining 42 between the shell 38 and a portion of the working

lining 50.

As noted above, the working lining 50 preferably is a castable refractory, although other

lining materials also may be used. The secondary lining 42 is a refractory exhibiting fluid

properties, and preferably a dry-vibratable refractory. The lining method also may include one or more additional steps. A sealing layer 46,

formed from a layer of ramming material or by another suitable method, may be provided

between the bottom portion 52 of the working lining 50 and the corresponding portion 42B of

the secondary lining to prevent damage to the dry-vibratable refractory during installation of

the working lining 50. A retainer 44 may be provided between a wall portion 54 of the

working lining 50 and the corresponding portion 42A of the secondary lining. A sealing layer

46 comprising a ramming refractory may assist in maintaining the retainers 44 in position.

In addition, a heat-resistant, moisture-permeable web 49 may be provided between the

dry-vibratable layer 42 and the shell 38 to cover any surface venting perforations in the shell.

The surface venting holes may be plugged after the liner is completely dried.

When castable refractory concrete is installed in a hot blast cupola or separator as the

working lining by casting, a forming system must be employed in order to establish the final

configuration of the inside of the cupola or separator lining and to confine the castable

material to its finished shape during the curing period or until it becomes sufficiently strong to

be self-supporting. The forming system must be of sufficient strength to resist the pressure

and buoyant force of the refractory concrete mass in a fluid state and must be constructed so

as to be removable without disturbing the structural integrity of the solidified monolithic

refractory mass. If the secondary lining is installed before the working lining, it may assist in shaping the exterior of the cast lining. The installation procedure for a castable refractory concrete lining consists of: (1)

forming, (2) casting (pouring), (3) curing, (4) form removal, and (5) drying and heating to

operating temperature. Each of these steps is discussed in more detail below.

Forming of the inside cavity of the cupola hearth and the separators can be done as described above using rigid materials such as steel, wood, or plastic or metal mesh.

Casting includes mixing the castable in a mechanical mixer with water or other liquids

and other ingredients to fluidize the material for installation purposes and activate the bonding

mechanism. When the castable refractory has been mixed for the prescribed amount of time or has reached the preferred consistency, it is poured, or pumped or otherwise transported to

the cupola and installed into the formed cavities. Many castable refractories tend to be

thixotropic, therefore, they may require vibration during installation in order to flow properly

or to consolidate into a monolithic mass of the highest possible density.

After the material has been cast into the formed cavity, a curing period normally is

required. During this period, the castable refractory mixture solidifies into a solid, monolithic

mass as the result of chemical reactions between the mixed ingredients. During the time

required for curing, the castable normally must be left undisturbed and maintained within a

prescribed temperature range. During the curing period, the castable refractory increases in

strength as a result of the desired chemical bonding reactions. The curing period is complete

when these reactions have proceed to completion or the castable has acquired sufficient strength to be self-supporting (referred to as "green strength"). When the curing period has been completed, the forms may be removed. In some

cases, forms or parts of forms of specific designs may be left in place to become a part of the

lining structure or to be consumed in due course during the operation of the cupola.

Before starting and operating the cupola, the lining normally is dried by applying heat

either directly or indirectly in a controlled manner to the refractory lining. The purpose of this

drying procedure is to remove water or other liquids that remain in the lining. The result of

not properly drying the materials can be the uncontrolled generation of a large volume of

steam or other gasses during either the heat-up to the operating temperature or operation of the

cupola. In extreme cases, the steam or gases generated can create sufficient pressure to cause

disruption of the lining (steam spalling) or explosion of gases that can accumulate as a result of various chemical reactions taking place in the lining.

After drying, the temperature of the lining may be increased gradually toward the

operating temperature. During the drying and heat-up period, many desirable and

consequential chemical and physical reactions may take place in the lining, and the increasing

temperature of the lining may accelerate these reactions. These reactions usually include the

expansion of the lining, which must be accommodated in the lining design. The result of not

properly allowing for expansion in the design can be catastrophic failure of the lining

components or the cupola structure. When drying and heat-up are completed, the lining is ready for the cupola start-up procedure to begin.

In some cases, the castable refractory may be installed using formless installation

techniques, such as gunite or shotcrete installation techniques. Such installation method avoid the need for interior forms during installation of the working lining walls, resulting in

significant time and cost savings. Use of formless installation techniques is particularly

advantageous during repairs to minimize downtime; however, they may be used in new installations as well. As with casting installation techniques, the secondary lining may be

used to assist in shaping the exterior of a castable lining installed using formless techniques.

In some instances, the use of a refractory castable working lining described above is

not possible or practical. In these instances, the dry-vibratable secondary liner of the present invention may be used effectively in conjunction with other conventional and

nonconventional working linings. Some of these alternatives are described below.

The working lining may be formed from cupola lining blocks or bricks. When these

materials are used, the dry-vibratable bottom layer is installed and compacted (vibrated) using

conventional methods. The cupola blocks or bricks are installed at a predetermined distance

from the cupola shell. Dry-vibratable refractory is then installed in the annular space behind

the blocks or bricks. Precast retainer shapes are not required to maintain the dry-vibratable

material in position along the sides of the shell.

The working lining also may be formed from ramming or plastic refractory material.

For these types of working linings, the dry-vibratable lining may be installed as described for

the castable working lining using precast retainer shapes to maintain the dry-vibratable

material in position along the sides of the shell. The rammed lining may be installed over the

dry-vibratable lining with or without the use of a ramming form. The design of the present invention, including selection of particular materials for the

working lining and the secondary lining and their respective thicknesses, is made using

conventional thermal analysis and liner design techniques. Among the factors considered in

designing a liner for a particular operating conditions are (1) the boundary conditions relating

to the dimensions of the shell and the desired capacity of the molten metal pool, (2) the

identity and physical properties of the metal, and (3) the expected operating environment of

the vessel, including its rated capacity and the presence of features such as oxygen injection,

plasma torches, and water or air cooling devices. A thermal profile of the vessel is developed

based upon these factors. Materials are selected based on this profile and desired operating

conditions (including, but not limited to, campaign time, ease of repair and material costs.)

Generally, materials are selected for the working lining and the secondary lining such that the

temperature at the interface of these structures is below the freezing temperature of the metal

to be process in the vessel, and the temperature at the interface of the secondary lining and the

shell is low enough to maintain the structural integrity of the shell.

In particular, the dry-vibratable material is selected based upon the thermal

environment of the furnace and the chemical and metallurgical reactions to be carried out in

the furnace. The dry-vibratable materials must be resistant to the temperatures and types of

metal(s) and slag(s) inherent to the metallurgical process. For example, the dry-vibratable

material in a hot blast cupola used for melting iron must be capable of withstanding

temperatures of about 2500 to 3000 °F. or more, under pressure, in a reducing atmosphere. The dry-vibratable material is selected with an appropriate sintering temperature range that will allow the formation of strong ceramic bonds in the region adjacent to the

working lining as a result of exposure to the operating conditions expected in this region.

The bonded dry-vibratable material will be dense and hard. It also will be chemically and

physically resistant to penetration of both molten metal and slag. The dry-vibratable material

outside this region, which generally is exposed to less severe operating conditions, will

remain in its unbonded state. The unbonded dry-vibratable material is able to absorb and

distribute local stresses without formation of cracks. However, the unbonded dry-vibratable

material remains capable of forming strong ceramic bonds in those areas where it may be

exposed to more severe operating conditions, for example, if molten metal or slag penetrates through the working lining and the bonded dry-vibratable material.

A liner of the present invention has been installed and tested in a dry bottom hot blast

cupola in an integrated steel manufacturing plant. This steelmaking operation required a

uninterrupted high volume supply of basic pig iron having consistent temperature and

chemistry over an extended operating period. At full production, the cupola was expected to

have a capacity in the range of about 100-150 tons of iron per hour or about 3000-3500 tons

per operating day. The desired campaign time (without requiring shutdown of the cupola to

repair or replace the hearth lining) was about 26 weeks or more, and preferably about 52

weeks or more.

The cupola designed for this plant contemplated the use of a conventional ramming

refractory liner. It soon became clear, however, that a conventional rammed liner would be consumed too quickly under the expected operating conditions (probably in about nine to

twelve weeks) and thus the cupola would not be capable of achieving the campaign time

desired. Although it was recognized that use of a castable refractory liner, and particularly an

ultra- low cement castable liner, might provide a longer operating life than noncastable

refractories such as ramming material and would also allow localized repair to be made to worn, contaminated or damaged portions of the lining, the brittle character of castable

refractory liners discouraged consideration of such a liner, particularly in view of the metal

burden and the stringent operating conditions.

The liner of the present invention provided a fluid refractory secondary lining in

combination with a rigid castable working lining. The resultant liner provides excellent

resistance to crack propagation and is easy to repair. The fluid secondary lining protects the

structural elements of the cupola from expansion of the rigid refractory. It also insulates the working lining, reducing the thermal gradient across the working lining. These features may

contribute to extending the operating life of the working lining.

Novel methods of installing the liner of the invention, described above, were

developed to allow installation of the dry-vibratable layer between the walls of the working

lining and the shell and to allow use of this liner in a shell that was designed for conventional

ramming and plastic refractories. A novel method also was developed to accommodate the

provision of large radial venting channels through the sides of the secondary lining and into

the bottom of the working lining to allow moisture, steam and other gases present in the working lining to escape during dryout and heatup. The venting channels were provided by installing stainless steel sleeves radially

through the openings in the sides of the shell, across the annular space defined by the shell

and the retainers, and through the retainers. The dry-vibratable material was installed in the

annular space after the sleeves were in position. Solid steel rods were then inserted through

the sleeves, extending into the center of the castable lining bottom. After the castable lining

was installed and cured, the solid rods were removed, leaving radial voids in the bottom of the castable lining. These voids allow moisture, steam and other gases present in the castable

lining to escape during dryout and heatup. The stainless steel sleeves remained in the side

walls of the secondary lining after the rods were removed to isolate the dry-vibratable material

from the venting channels and prevent it from leaking out of the openings in the shell. After drying, the channels were filled with refractory material. This helps to exclude air from the

lining and may reduce the oxidation of certain components of the refractory lining.

Although a specific embodiment of the invention has been described herein in detail, it

is understood that variations may be made thereto by those skilled in the art without departing

from the spirit of the invention or the scope of the appended claims.

Claims

What is Claimed Is:

1. A liner for the shell of a vertical shaft metallurgical vessel, comprising:

a working lining within the shell; and

a secondary lining inteφosed between the shell and a portion of the working lining,

said secondary lining comprising a refractory exhibiting fluid properties.

2. The liner according to Claim 1, wherein said fluid refractory comprises a dry- vibratable refractory.

3. The liner according to Claim 1 , wherein said secondary lining extends over a

portion of the bottom of the shell.

4. The liner according to Claim 3, wherein said secondary lining further extends

over a portion of a wall of the shell.

5. The liner according to Claim 1, wherein said secondary lining extends over a portion of a wall of the shell.

6. The liner according to Claim 3, further comprising: a sealing layer inteφosed between a bottom portion of the secondary lining and a

corresponding portion of the working lining.

7. The liner according to Claim 5, further comprising:

a retainer inteφosed between a wall portion of the secondary lining and a

corresponding portion of the working lining.

8. The liner according to Claim 1, further comprising:

a web inteφosed between the shell and a portion of the secondary lining.

9. The liner according to Claim 1 , wherein said working lining comprises a

castable refractory.

10. The liner according to Claim 1 , wherein said working lining comprises

refractory blocks.

11. The liner according to Claim 1 , wherein said working lining comprises refractory bricks.

12. The liner according to Claim 1 , wherein said working lining comprises plastic

refractory.

13. The liner according to Claim 1, wherein said working lining comprises

ramming refractory.

14. A liner for the shell of a vertical shaft metallurgical vessel, comprising: a rigid refractory working lining within the shell; and

a secondary refractory lining inteφosed between the shell and a portion of the working lining, a portion of said secondary lining exhibiting fluid properties.

15. The liner according to Claim 14, wherein said secondary lining accommodates

expansion of said rigid working lining during heating of the rigid lining.

16. A liner for the shell of a vertical shaft metallurgical vessel, comprising: a working lining within the shell, said working lining extending over the bottom and a

portion of a wall of the shell;

said secondary lining comprising a refractory exhibiting fluid properties; a sealing layer inteφosed between a bottom portion of the secondary lining and a

corresponding portion of the working lining; and

a web inteφosed between the shell and a portion of the secondary lining.

17. The liner according to Claim 16, further comprising: a retainer inteφosed between a wall portion of the working lining and a corresponding

portion of the secondary lining.

18. The liner according to Claim 17, further comprising:

a coating layer covering the upper surface of the secondary lining located between the

retainer and a wall portion of the shell.

19. A liner for the shell of a hot blast cupola, comprising:

a working lining within the shell; and

a secondary lining inteφosed between the shell and a portion of the working lining, said secondary lining comprising a refractory exhibiting fluid properties.

20. The liner according to Claim 19, wherein said fluid refractory comprises a dry-

vibratable refractory.

21. A liner for the shell of hot blast cupola, comprising:

a working lining within the shell, said working lining extending over the bottom and a

portion of a wall of the shell;

a secondary lining interposed between the shell and a portion of the working lining,

corresponding portion of the working lining; and a web inteφosed between the shell and a portion of the secondary lining.

22. The liner according to Claim 21 , further comprising:

a retainer inteφosed between a wall portion of the working lining and a corresponding

portion of the secondary lining.

23. A liner for the slag separator of a vertical shaft metallurgical vessel,

comprising:

a working lining within the slag separator, said working lining extending over a

portion of an inner surface of the slag separator; and

said secondary lining comprising a refractory exhibiting fluid properties.

24. A liner for the transition area between the hearth and a slag separator of a vertical shaft metallurgical vessel, comprising:

a working lining within the transition area, said working lining extending over a

portion of an inner surface of the transition area; and

said secondary lining comprising a refractory exhibiting fluid properties.

25. A liner for a vertical shaft metallurgical vessel having a shell, said shell

including a hearth and an integral slag separator, said liner comprising:

a working lining, said working lining continuously extending over a portion of the hearth and a portion of the integral slag separator; and

said secondary lining comprising a refractory exhibiting fluid properties.

26. The liner according to Claim 25, wherein said secondary liner extends

continuously over a portion of the hearth and a portion of the integral slag separator.

27. A method for lining a vertical shaft metallurgical vessel having a shell, said

method comprising the steps of:

providing a working lining within the shell; and

providing a secondary lining between the shell and a portion of the working lining,

said secondary lining comprising a refractory exhibiting fluid properties.

28. The method according to Claim 27, wherein the step of providing a secondary

lining further comprises the step of:

installing a dry-vibratable refractory.

29. The method according to Claim 27, wherein the step of providing a secondary

lining further comprises the step of:

installing the secondary lining over a portion of the bottom of the shell.

30. The method according to Claim 27, wherein the step of providing a secondary lining further comprises the step of:

installing the secondary lining adjacent to a portion of a wall of the shell.

31. The method according to Claim 30, further comprising the step of:

providing a retainer between the secondary lining adjacent to a portion of a wall of the

shell and a corresponding portion of the working lining.

32. The method according to Claim 29, further comprising the step of:

providing a sealing layer between a bottom portion of the secondary lining and a

corresponding portion of the working lining.

33. The method according to Claim 27, further comprising the step of:

providing a web between the shell and a portion of the secondary lining.

34. The method according to Claim 27, wherein the step of providing a working lining further comprises the step of: selecting a refractory lining material from among: castable refractory, refractory

bricks, refractory blocks, ramming refractory, and plastic refractory.

35. The method according to Claim 34, wherein the step of providing a working lining further comprises the step of:

installing a castable refractory using forms.

36. The method according to Claim 34, wherein the step of providing a working

lining further comprises the step of:

installing a castable refractory using a formless method.

37. The method according to Claim 27, wherein the step of providing a secondary

lining further comprises the step of:

providing a structure that assists in shaping of the working lining.

38. A method for lining a hot blast cupola, comprising the steps of:

providing a working lining within the shell of the cupola; and

said secondary lining comprising a refractory exhibiting fluid properties.

39. The method according to Claim 38, wherein the step of providing a secondary

lining further comprises the step of:

installing a dry-vibratable refractory.

40. A method for lining a vertical shaft metallurgical vessel having a shell, said

method comprising the steps of:

providing a working lining within the shell, said working lining extending over the bottom and at least a portion of the walls of the shell;

said secondary lining comprising a refractory exhibiting fluid properties; and providing a sealing layer between a portion of secondary lining and a corresponding

portion of the working lining.

41. The method according to Claim 40, further comprising the steps of: installing the secondary lining adjacent to a portion of a wall of the shell; and

providing a retainer between a wall portion of the secondary lining and a

corresponding portion of the working lining.

42. The method according to Claim 40, further comprising the step of:

providing a web between the shell and a portion of the secondary lining.