CA1172431A - Process for repairing refractory linings - Google Patents
Process for repairing refractory liningsInfo
- Publication number
- CA1172431A CA1172431A CA000392661A CA392661A CA1172431A CA 1172431 A CA1172431 A CA 1172431A CA 000392661 A CA000392661 A CA 000392661A CA 392661 A CA392661 A CA 392661A CA 1172431 A CA1172431 A CA 1172431A
- Authority
- CA
- Canada
- Prior art keywords
- composition
- process according
- refractory
- elements
- lining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Furnace Housings, Linings, Walls, And Ceilings (AREA)
- Ceramic Products (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE.
The invention relates to a process for repairing hot refractory linings by applying a refractory composition by spraying on to the part of the lining to be repaired. The invention resides in the improvement comprising applying a composition containing an effective amount of combustible elongated channel-forming elements substantially evenly distributed throughout the composition.
The invention relates to a process for repairing hot refractory linings by applying a refractory composition by spraying on to the part of the lining to be repaired. The invention resides in the improvement comprising applying a composition containing an effective amount of combustible elongated channel-forming elements substantially evenly distributed throughout the composition.
Description
TI TLE OF I N VEN TI ON:
PROCESS ~OR REPAIF~ING P~EFRACTORY LININGS.
Industrial ~urnaces and other facilities ~or use at high temperatures provided with refrac~ory linings are sub~ect to more or less frequent shut down periods ~or repair o~ the lining. The bigger ~he facilit~ and the longer the shut down period required ~or a rep~ir, the bigger the fall off in production and thereby the capital loss.
Against this background there is a constant and increasing interest in finding new technique for repairing refractory linings requiring the shorkest possible time ~or the shut down.
Continuous repair Or the re~ractory lining must be provided for in ~or example steel melting furnaces. Such' ~urnaces~ such as o~ the type arc ~urnaces~ vary in size between 50 and 250 metric tons per charge. The slag zone of arc ~urnaces is repaired either a~ter each charge or after a number of charges. The re~ractory material is applied to the hot furnace lining by for example spraying or gunning. Spraying can be per~ormed either by applying refractory mass around the slag zone as a whole or so as to fill up local cavities.
To reduce the shut down period in connection with repair to the shortest possible time the re~ractory material must be applied to the area o~ the lining to be repaired while the lining is still hot. Cooling down the whole ~urnace would be unrealistic in view of the extension of the shut down period such measure would cause. A common problem in spraying the re~ractory composition or mass onto the hot lining to be repaired is the phenomenon residing in bursting or peeling of the material applied in view Or the evaporization o~
mechanically and chemically bound water ~ .
.. ~ .
f9~
contained in the mass. In actual practice this problem is of such a magnitude that gunning or spraying a refractory lining while hot I'or the purpose of repairing same can be done only with great difficulty and the spraying procedure must be per~ormed repeatedly adding only a thin layer of refractory mass each time.
It is important to note that the possibility of efficiently repairing a refractory lining while it is still hot constitutes a high~y desirable and cost-saving procedure, which greatly adds to the economy of the maintenance of refractory linings.
Accordingly, the present invention has f'or its main object to provide a process enabling the repair of refractory linings while still hot by spraying a 1~ refractory composition onto the lining in need of repair.
Anokher object of the invention is to provide a process using a refractory composition enabling the evaporized water contained therein to escape as through the exposed surface o~ the composition when applied to the refractory lining to be repaired.
These and other objects of the present invention are attained in a very simple and effective way by applying a ref'ractory composition containing combustible elongated channel-forming elements which are substantially evenly distributed throughout the composition.
Preferred channel~forming elements are based on natural materials originating from plants, such as for example straws or stalks of cornmon cereals, grass, rice roots, fibres from palm trèes, needles from pine trees ~0 and the like. Since capillary forces are usèful for enabling the water to escape from the composition the diameter of the said elements may vary from a few microns up to several millimeters. In practical application of the invention palm tree fibres are highly ~5 preferred since said fibres have a small diameter, a high '7~3~L
density and are quite rigid. In hot lining repair this type of fibre finds i-ts way easier up to the hot surface then perhaps other materials. In view of its high mechanical streng-th the palm tree fibre also results in good reinforcement of the composition when applied. (This type of fibre is frequen-tly sold under the commercial name "Bassine"*).
Alterna-tive materials for the channel-forming elements are prefabric-ated fibres or tubes made from suitable plastic materials, such as polyprop~
lene. Such materials or elements may be solid having a diameter from some tenths of microns up to a few millimeters, or they may be tubular in shape, such as sucking straws, with a diameter of the order of millimeters/ such as from 1 to 5 millimeters.
The channel-forming elements can be used in relatively minor amounts.
A preferred proportion of elements lies within the range of 0.05 to 0.5 % by weight of the composition as a whole. A preferred range is about 0.1 to 0.3 %
by weight, such as about 0.2 %.
In order to provide for channels in the refractory composi-tion when applied, the channel-forming elements shall be elongated, i.e. have a high length/diameter ratio. The length of the elements may vary within very broad limits and a preferred range is from about 5 millimeters to about 10 centi-meters. To enable ease in admixing the elements with the rest of the compos-ition it is preferred that the leng-th does not exceed about 5 centimeters, and a particularly preferred range is about 1 to 3 centimeters.
In regard to the composition of the refractory material any commonly used refractory oxides are conceivable. Thus, acid refractory compositions containing mainly sio2 or ~rO2, any neutral refractory compositions containing Y 2 3 or Cr2O3 or any basic refractory composition containing mainly r~go * Trade mark ~ 3 ' ~7~
or CaO can be used in applying the -technique of the invention.
The re~ractory oxide forms the major part of the composition of the invention and the weight ratio -thereof lies suitably within the range about 75 to about 95 % by weight of the composition. The composi-tion also contains a minor amoun-t of binder, such as high alumina cement, phosphoric acid or clay.
~ efractory compositions useful in the inven-tion are of a conventional nature and are also usually called gunning mixes, since the mixtures of refrac-tory grains are applied by means of a spray gun. It is preferred to use a minor amount of the binder to aid adherence to the surface of the lining to be repaired. Said gunning mixes are generally finer grained -than regular cas-tables consisting of refractory grains and hydraulic binders.
The compositions of the inven-tion are prepared in a conventional manner by mixing the ingredients, such as in a mixing pan containing mixing means, the pan being heated if desired, and -the channel-forming elements can be admixed with the rest of the composition at any stage of i-ts manufacture.
To apply the composition containing channel-forming elements onto the lining to be repaired there may be used conventional spray guns/ such as Arenco*, Besab*, Aliwa*, Piccola*, or a particular spray gun of a rotary type with for example centrifugal action, such as Aliwa*, Schleuder*.
In practising the present invention it has been unexpectedly found that hot linings can be successfully repa.red using the process of the invention in a minimum of time and with a minimum of composition waste. Thus, -thick layers of the order of several centimeters can be rapidly built up without water vapour b~ursting occurring, and this means economic advantages in that significantly short shut-down periods for repair will be required * T=ade mark using the techniq~le of the invention.
The invention will in the following be ~urther illustrated by non-limiting examples. In the e~amples, all percentages are based upon weight if not otherwise stated.
Example 1.
A high-alumina refractory gunning mix is prepared from the following ingredients:
Sintered alumina, -5 mm (A120~)85 %
Clay 5 %
High alumina cement CA 25 10 %
Palm tree fiber (Bassine) 0.2 %
The above ingredients are mixed in a mixer of the type Eirich-mixer to form a gunning mix. The mix is used for hot repair of the lining of a steel melting furnace of the type arc furnace, the repair being performed at a lining temperature of about 1400C.
The spray rate is about 2-5 tons/h and the refractory layer applied has an average thickness of about 10 centimeters. No bursting occurs during applying the gunning mix and very little material waste is formed.
Example 2.
A basic gunning mix is prepared from the following ingredients:
Magnesite, -5 mm ~5 %
Magnesite, -0.25 mm 15 %
H~P01~ 4 %
Chopped barley straw (average length about 2 cm) 0.25 %
~0 The above ingredients are mixed in a mixer of the same type as that used in Example 1 and the gunning mix obtained is used for repairing the slag zone around the mantle surface of the lining of a steel melting furnace.
- . ' .
`
, ~ 7~3~
The spray gun is operated at a ~low rate o~ 200-5000 ~gs/h and the lining to be repaired has a temperature varying from about 1450C down to about 1100C. rme gunning mix is applied to a thickness of about 10 centimeters. In applying the mix no noticeable vapour bursting occurs and the waste o~ material is negligible.
Example ~.
Example 2 is repeated using a semibasic gunning mix prepared ~rom the following ingredients:
Olivine, -5 mm 80 %
Magnesite, -0.25 mm 10 ~
High alumina cement 10 %
Plastic ribre, diameter ~15 microns, average length ~10 mm o.o6 %
Similar favourable results as those of Example 2 are obtained.
Example 4.
Example 2 is repeated using a gunning mix prepared from the ~ollowing ingredients:
Quartzite, -5 mm 80 %
Quartzite, 0.25 rnm 15 %
Clay 5 ~
Palm tree fibre as in Example 10.15 %
Similar results as those according to Example 2 are obtained.
It is to be understood that the present invention is not limited to the embodiments illustrated above.
Thus, the process of the invention is applicable to repair o~ any type of rerractory lining while hot. The ~0 examples given above only constitute preferred embodi-ments of the invention and equivalents and modi~ications of the ~eatures thereo~ are obvious to those skilled in the art. Thus, the invention is limited only inso~ar as the scope o~ the appended claims is concerned.
:
PROCESS ~OR REPAIF~ING P~EFRACTORY LININGS.
Industrial ~urnaces and other facilities ~or use at high temperatures provided with refrac~ory linings are sub~ect to more or less frequent shut down periods ~or repair o~ the lining. The bigger ~he facilit~ and the longer the shut down period required ~or a rep~ir, the bigger the fall off in production and thereby the capital loss.
Against this background there is a constant and increasing interest in finding new technique for repairing refractory linings requiring the shorkest possible time ~or the shut down.
Continuous repair Or the re~ractory lining must be provided for in ~or example steel melting furnaces. Such' ~urnaces~ such as o~ the type arc ~urnaces~ vary in size between 50 and 250 metric tons per charge. The slag zone of arc ~urnaces is repaired either a~ter each charge or after a number of charges. The re~ractory material is applied to the hot furnace lining by for example spraying or gunning. Spraying can be per~ormed either by applying refractory mass around the slag zone as a whole or so as to fill up local cavities.
To reduce the shut down period in connection with repair to the shortest possible time the re~ractory material must be applied to the area o~ the lining to be repaired while the lining is still hot. Cooling down the whole ~urnace would be unrealistic in view of the extension of the shut down period such measure would cause. A common problem in spraying the re~ractory composition or mass onto the hot lining to be repaired is the phenomenon residing in bursting or peeling of the material applied in view Or the evaporization o~
mechanically and chemically bound water ~ .
.. ~ .
f9~
contained in the mass. In actual practice this problem is of such a magnitude that gunning or spraying a refractory lining while hot I'or the purpose of repairing same can be done only with great difficulty and the spraying procedure must be per~ormed repeatedly adding only a thin layer of refractory mass each time.
It is important to note that the possibility of efficiently repairing a refractory lining while it is still hot constitutes a high~y desirable and cost-saving procedure, which greatly adds to the economy of the maintenance of refractory linings.
Accordingly, the present invention has f'or its main object to provide a process enabling the repair of refractory linings while still hot by spraying a 1~ refractory composition onto the lining in need of repair.
Anokher object of the invention is to provide a process using a refractory composition enabling the evaporized water contained therein to escape as through the exposed surface o~ the composition when applied to the refractory lining to be repaired.
These and other objects of the present invention are attained in a very simple and effective way by applying a ref'ractory composition containing combustible elongated channel-forming elements which are substantially evenly distributed throughout the composition.
Preferred channel~forming elements are based on natural materials originating from plants, such as for example straws or stalks of cornmon cereals, grass, rice roots, fibres from palm trèes, needles from pine trees ~0 and the like. Since capillary forces are usèful for enabling the water to escape from the composition the diameter of the said elements may vary from a few microns up to several millimeters. In practical application of the invention palm tree fibres are highly ~5 preferred since said fibres have a small diameter, a high '7~3~L
density and are quite rigid. In hot lining repair this type of fibre finds i-ts way easier up to the hot surface then perhaps other materials. In view of its high mechanical streng-th the palm tree fibre also results in good reinforcement of the composition when applied. (This type of fibre is frequen-tly sold under the commercial name "Bassine"*).
Alterna-tive materials for the channel-forming elements are prefabric-ated fibres or tubes made from suitable plastic materials, such as polyprop~
lene. Such materials or elements may be solid having a diameter from some tenths of microns up to a few millimeters, or they may be tubular in shape, such as sucking straws, with a diameter of the order of millimeters/ such as from 1 to 5 millimeters.
The channel-forming elements can be used in relatively minor amounts.
A preferred proportion of elements lies within the range of 0.05 to 0.5 % by weight of the composition as a whole. A preferred range is about 0.1 to 0.3 %
by weight, such as about 0.2 %.
In order to provide for channels in the refractory composi-tion when applied, the channel-forming elements shall be elongated, i.e. have a high length/diameter ratio. The length of the elements may vary within very broad limits and a preferred range is from about 5 millimeters to about 10 centi-meters. To enable ease in admixing the elements with the rest of the compos-ition it is preferred that the leng-th does not exceed about 5 centimeters, and a particularly preferred range is about 1 to 3 centimeters.
In regard to the composition of the refractory material any commonly used refractory oxides are conceivable. Thus, acid refractory compositions containing mainly sio2 or ~rO2, any neutral refractory compositions containing Y 2 3 or Cr2O3 or any basic refractory composition containing mainly r~go * Trade mark ~ 3 ' ~7~
or CaO can be used in applying the -technique of the invention.
The re~ractory oxide forms the major part of the composition of the invention and the weight ratio -thereof lies suitably within the range about 75 to about 95 % by weight of the composition. The composi-tion also contains a minor amoun-t of binder, such as high alumina cement, phosphoric acid or clay.
~ efractory compositions useful in the inven-tion are of a conventional nature and are also usually called gunning mixes, since the mixtures of refrac-tory grains are applied by means of a spray gun. It is preferred to use a minor amount of the binder to aid adherence to the surface of the lining to be repaired. Said gunning mixes are generally finer grained -than regular cas-tables consisting of refractory grains and hydraulic binders.
The compositions of the inven-tion are prepared in a conventional manner by mixing the ingredients, such as in a mixing pan containing mixing means, the pan being heated if desired, and -the channel-forming elements can be admixed with the rest of the composition at any stage of i-ts manufacture.
To apply the composition containing channel-forming elements onto the lining to be repaired there may be used conventional spray guns/ such as Arenco*, Besab*, Aliwa*, Piccola*, or a particular spray gun of a rotary type with for example centrifugal action, such as Aliwa*, Schleuder*.
In practising the present invention it has been unexpectedly found that hot linings can be successfully repa.red using the process of the invention in a minimum of time and with a minimum of composition waste. Thus, -thick layers of the order of several centimeters can be rapidly built up without water vapour b~ursting occurring, and this means economic advantages in that significantly short shut-down periods for repair will be required * T=ade mark using the techniq~le of the invention.
The invention will in the following be ~urther illustrated by non-limiting examples. In the e~amples, all percentages are based upon weight if not otherwise stated.
Example 1.
A high-alumina refractory gunning mix is prepared from the following ingredients:
Sintered alumina, -5 mm (A120~)85 %
Clay 5 %
High alumina cement CA 25 10 %
Palm tree fiber (Bassine) 0.2 %
The above ingredients are mixed in a mixer of the type Eirich-mixer to form a gunning mix. The mix is used for hot repair of the lining of a steel melting furnace of the type arc furnace, the repair being performed at a lining temperature of about 1400C.
The spray rate is about 2-5 tons/h and the refractory layer applied has an average thickness of about 10 centimeters. No bursting occurs during applying the gunning mix and very little material waste is formed.
Example 2.
A basic gunning mix is prepared from the following ingredients:
Magnesite, -5 mm ~5 %
Magnesite, -0.25 mm 15 %
H~P01~ 4 %
Chopped barley straw (average length about 2 cm) 0.25 %
~0 The above ingredients are mixed in a mixer of the same type as that used in Example 1 and the gunning mix obtained is used for repairing the slag zone around the mantle surface of the lining of a steel melting furnace.
- . ' .
`
, ~ 7~3~
The spray gun is operated at a ~low rate o~ 200-5000 ~gs/h and the lining to be repaired has a temperature varying from about 1450C down to about 1100C. rme gunning mix is applied to a thickness of about 10 centimeters. In applying the mix no noticeable vapour bursting occurs and the waste o~ material is negligible.
Example ~.
Example 2 is repeated using a semibasic gunning mix prepared ~rom the following ingredients:
Olivine, -5 mm 80 %
Magnesite, -0.25 mm 10 ~
High alumina cement 10 %
Plastic ribre, diameter ~15 microns, average length ~10 mm o.o6 %
Similar favourable results as those of Example 2 are obtained.
Example 4.
Example 2 is repeated using a gunning mix prepared from the ~ollowing ingredients:
Quartzite, -5 mm 80 %
Quartzite, 0.25 rnm 15 %
Clay 5 ~
Palm tree fibre as in Example 10.15 %
Similar results as those according to Example 2 are obtained.
It is to be understood that the present invention is not limited to the embodiments illustrated above.
Thus, the process of the invention is applicable to repair o~ any type of rerractory lining while hot. The ~0 examples given above only constitute preferred embodi-ments of the invention and equivalents and modi~ications of the ~eatures thereo~ are obvious to those skilled in the art. Thus, the invention is limited only inso~ar as the scope o~ the appended claims is concerned.
:
Claims (10)
1. In a process for repairing hot refractory linings by applying a refractory composition by spraying onto the site to be repaired the improvement comprising applying a composition containing combustable elongated channel-forming elements substantially evenly distributed throughout the composition.
2. A process according to claim 1, wherein said elements constitute about 0.05-0.5 % by weight of the composition.
3. A process according to claim 1, wherein said elements are selected from the group comprising straws and stalks of cereals, grass, rice roots, palm tree fibres, pine needles, plastic fibres and tubes.
4. A process according to claim 3, wherein the length of said elements is within the range about 5 mms to about 10 cms.
5. A process according to claim 1, wherein the composition is applied by spraying of same onto the site.
6. A process according to claim 1, wherein the composition is based on a refractory mass selected from the group comprising acid neutral and basic masses.
7. A process according to claim 1, wherein said elements consist of palm tree fibres.
8. A process according to claim 1, wherein the composition is applied locally to fill out local cavities.
9. A process according to claim 1, wherein the composition is applied onto the whole worn out surface of the lining.
10. Refractory lining whenever repaired by the process of claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000392661A CA1172431A (en) | 1981-12-18 | 1981-12-18 | Process for repairing refractory linings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000392661A CA1172431A (en) | 1981-12-18 | 1981-12-18 | Process for repairing refractory linings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1172431A true CA1172431A (en) | 1984-08-14 |
Family
ID=4121651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000392661A Expired CA1172431A (en) | 1981-12-18 | 1981-12-18 | Process for repairing refractory linings |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1172431A (en) |
-
1981
- 1981-12-18 CA CA000392661A patent/CA1172431A/en not_active Expired
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Legal Events
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| MKEC | Expiry (correction) | ||
| MKEX | Expiry |