CA2024106C - Refractory composition and use thereof - Google Patents
Refractory composition and use thereof Download PDFInfo
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- CA2024106C CA2024106C CA 2024106 CA2024106A CA2024106C CA 2024106 C CA2024106 C CA 2024106C CA 2024106 CA2024106 CA 2024106 CA 2024106 A CA2024106 A CA 2024106A CA 2024106 C CA2024106 C CA 2024106C
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Abstract
A refractory composition for use in forming a refractory lining on a surface to protect the surface against high temperatures and against abrasion, consists of 6 to 8 percent by weight of a volatilised silica, 5 to 8 percent by weight of a calcium aluminate cement, 0,1 to 3,0 percent by weight of a dispersant such as a sodium polyphosphate, and the balance of a hard refractory oxide aggregate having a particle size distribution such that at least 45 percent by weight of the particles are 1mm or greater in size.
Description
BACKGROUND OF THE INVENTION
This invention relates to a refractory composition for use in forming a refractory lining on a surface i~o protect the surface against high temperatures and against abrasion, and to a method of forming such a refractory lining.
The surfaces of equipment used in many industrial processes need to be protected against high temperatures and against abrasion.
Generally this is achieved by locating on the surfaces to be protected a thin refractory lining, typically 20 to 50mm in thickness. Generally, these linings are formed by locating on the surface to be protected, studs, hexmesh or S-bar anchors or the like to hold a refractory composition in place, and then covering the surface with the refractory composition which is applied by trowelling, ramming or hand-placing.
In the petrochemical industry, the standard refractory composition used to form such linings i.s Resco-AA-22. This composition is a two-component, phosphate bonded, high alumina composition. In recent years other phosphate bonded compositions, either two-component compositions, or one-component compositions, have been considered as alternatives to Resco-AA-22.
In addition, the development of the so-called "low-cement bonding technology" has led to the development of very high strength compositions, supplied as one-component mixes, as alternatives to Resco-AA-22* Such compositions typically contain j to 7,5 percent by weight of the composition oa a calcium alumina~e cement, 2,5 to 5,0 percent by weight of the composition of a volatilised (fumed) silica and 0,1 to 1,O percent by weight of the composition of a dispersing agent. In these compositions, the amount by weight of calcium aluminate cement is always the same as or greater than the amount by we_Lght of the volatilised silica in the composition. In these compositions, the maximum percentage by weight of volatilised silica is 5 percent by weight. Volatilised or fumed silica generally is of two types.
The first type is that produced as a waste by-product from silicon smelters or the like. The second type is that specifically produced from a silicon source.
Although there are several types of refractory compositions which may be used to form refractory linings on surfaces, there is always a need for a new refractory composition which will provide greater abrasion resistance or some other advantage.
* trade-mark SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a refractory composition comprising:
(a) 6 t,o 8 percent by weight of the composition of a volatilised silica;
(b) 5 to 8 percent by weight of the composition of a calcium aluminate cement;
(c) 0;1 to 3,0 percent by weight of the composition of suitable dispersant; and (d) the balance by weight of the composition of a hard refractory oxide aggregate having a particle size distribution such that at least q.5 percent by weight of the particles are lmm or greater in size.
The composition of the invention is adapted to be mixed with water to form a composition of sufficient plasticity for application to a surface to form a refractory lining.
According to another aspect of the invention, there is provided a method of forming a refractory lining; from a refractory composition on a surface which includes the steps of:
(i) locating means for supporting the refractory composition in place, such as studs, a metallic mesh, e.g. hexmesh, or S-bar anchors, on the surface;
(ii) mixing the refractory composition comprising:
(a) 6 to 8 percent by weight of the composition of a volatilised silica;
-j-(b) 5 to 8 percent by weight of the composition of a calcium aluminate cement:
(c) 0,1 to ,3,0 percent by weight of the composition of a suitable dispersant: and (d) the balance by weight of the composition of a hard refractory oxide aggregate having a particle size distribution such that at least :~~ percent by weight of the particles are lmm or greater in size.
with water to form a mixture of suitable plasticity: and (iii) applying to the surface the mixture of step (ii) to form the lining.
DESCRIPTION OF PREFERRED EMBODIMENTS
The refractory composition of the invention comprises four components.
The first component of the composition is 6 to 8 percent by weight of the composition of a volatilised silica. The volatilised silica is preferably that produced as a waste by-product from silicon smelters or the like.
The second component of the composition is 5 to 8 percent by weight of the composition of a calcium. aluminate cement. An example of a suitable calcium aluminate cement is Secar %1 which is a proprietary product of Lafarge.
The third component of the composition is 0,1 to 3,0 percent by weight of the composition of a suitable dispersant. Suitable dispersants include a sodium polyphosphate or a sodium silicate.
The fourth component of the composition is a hard refractory * trade-mark oxide aggregate. The aggregate may, for example, tabular alumina, fused alumina or natural corundu~-~. The aggregate must have a particle size distribution such that at least 45 percent by weight of the particles are lmm or g-.reater in size. The maximum particle size of the aggregate will- depend on the method of application of the composition to a surface to form a refractory lining. For example, when hexme~sh is used to support the refractory composition in place, then the maximum particle size will be between 6mm and 8mm. However, when S-bar anchors are used, the maximum particle size may be greater, e.g. 12 to 20mm. It has been found tha t a composition which has an aggregate wherein at least q.$ percent of the particles have a particle size of 1mm or greater provides much better abrasion resistance than a composition with an aggregate having a smaller particle size.
The composition of the invention is designed to be mixed with a suitable percentage of water, e.g. about 3,5 to q.,5 percent by weight, to form a mixture which may be applied to a surface to form a refractory lining.
The second aspect of the invention is a method of forming a refractory lining using the' refractory composition of the invention. This method includes the steps of locating means for supporting the refractory composition in p7_ace, such as studs, a metallic mesh such as hexmesh, or S-bar anchors, on the surface to be protected, and then applying to the surface the refractory composition mixed with water, which may bcs applied by means of trowelling, ramming or hand-placing, to form the lining.
Examples of the refractory composition of 'the invention will now be given. In the examples, all percentages are given by weight.
Various compositions of the invention were formed as dry mixes and these are set out in Examples 1A, 1B, 2A, 2B, 3A, 3B 4A and 4B below. Each of these compositions was mixed with a percentage of water, as set out in Table 1 to form a mixture for use in _7_ forming a refractory lining. The mixtures, after drying at X50°C. were tested for their bulk density and for their cold crushing strength. The cold crushing strength test was performed on sample cubes 76 x 76 x 76mm in sire, prepared by hand-placing.
the mixture in a mould, without ramming or vibration. The results of these tests are also set out in. Table 1.
cwAUnTC 7 A
- 6mm graded tabular alumina 86,75 %
Volatilised silica 6,5 %
6~5 %
Secar 71 Dispersant 0,25 %
Lw A 1lT)T C t R
- 6mm graded tabular alumina 85,0 Volatilised silica 6,5 %
Secar 71* 6,5 Dispersant 2,0 L'Y A uDT Ti' 7 A
6mm graded tabular alumina 87,25 %
Volatilised silica 6,5 %
5,0 Secar 71 Dispersant 1,25 %
L'YAUDT Ti' 7R
6mm graded tabular alumina 88,38 Volatilised silica 6,5 Secar '71 ~ 5, 0 Dispersant 0,12 * trade-mark _g-- 6mm graded tabular alumina 83,5 Volatilised silica 6,5 Secar 71 8,0 Dispersant 2,0 ExAMPLE 3s - 6mm graded tabular alumina 85,0 Volatilised silica 6,5 Secar 71 8~0 Dispersant 0,5 cv w vnT z~ w ~
- 6mm graded tabular alumina81,0 0 Volatilised silica 8,0 Secar 7I 8,0 Dispersant 3,0 - 6mm graded tabular alumina 8 3,8 Volatilised silica 8,0 0 Secar 71~ 8~0 Dispersant 0,2 * trade-mask T A B 1. E 1 Example No lA ~ 1B ~ 2A ~ 2B 1 3A ~ 3B ~ øA ~ Q.B
Water Addition % ~ 4,5 I4,5 I3,5 ~3,5 I4.,5 I4,0 ~5,0 I4,5 Bulk Density g/cm3 ~ 2,952,9613,05~3,12I2,95I2,97~2,90I2,91 Cold Crushing Strength MPa ~ 120 1140 1120 1120 1180 1190 1115 1110 I
The comparative erosion resistance of the compositions of Examples lA, 1B, 2A, 2B, 3A, 3B, after mixture with water as set out in Table 1, as well as of certain known products was tested and the results are set out in Table 2 below.
Material ~ Average mm Eroded Plasticised Tabular Alumina Castable 1200 Resco-aA-22 1000 Low Cement, Sintered Alumina Ball Mix (HICAST 90BR)~ 300 214 ' 2a 3A I Less than 200 Less than 50/ Chamotte Mix Balance Corundum ( S5~ Andalusite Mix Balance Corundum ~
30~ Natural Corundum 30~ Andalusite Mie. . ~ 265 Balance Corundum * trade-mark From these results, it can be seen that th.e compositions of the invention have a much better abrasion or erosion resistance than previously known refractory compositions. 'thus, the main advantage of the composition of the invention is its superior abrasion resistance, in relation to its cost.
This invention relates to a refractory composition for use in forming a refractory lining on a surface i~o protect the surface against high temperatures and against abrasion, and to a method of forming such a refractory lining.
The surfaces of equipment used in many industrial processes need to be protected against high temperatures and against abrasion.
Generally this is achieved by locating on the surfaces to be protected a thin refractory lining, typically 20 to 50mm in thickness. Generally, these linings are formed by locating on the surface to be protected, studs, hexmesh or S-bar anchors or the like to hold a refractory composition in place, and then covering the surface with the refractory composition which is applied by trowelling, ramming or hand-placing.
In the petrochemical industry, the standard refractory composition used to form such linings i.s Resco-AA-22. This composition is a two-component, phosphate bonded, high alumina composition. In recent years other phosphate bonded compositions, either two-component compositions, or one-component compositions, have been considered as alternatives to Resco-AA-22.
In addition, the development of the so-called "low-cement bonding technology" has led to the development of very high strength compositions, supplied as one-component mixes, as alternatives to Resco-AA-22* Such compositions typically contain j to 7,5 percent by weight of the composition oa a calcium alumina~e cement, 2,5 to 5,0 percent by weight of the composition of a volatilised (fumed) silica and 0,1 to 1,O percent by weight of the composition of a dispersing agent. In these compositions, the amount by weight of calcium aluminate cement is always the same as or greater than the amount by we_Lght of the volatilised silica in the composition. In these compositions, the maximum percentage by weight of volatilised silica is 5 percent by weight. Volatilised or fumed silica generally is of two types.
The first type is that produced as a waste by-product from silicon smelters or the like. The second type is that specifically produced from a silicon source.
Although there are several types of refractory compositions which may be used to form refractory linings on surfaces, there is always a need for a new refractory composition which will provide greater abrasion resistance or some other advantage.
* trade-mark SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a refractory composition comprising:
(a) 6 t,o 8 percent by weight of the composition of a volatilised silica;
(b) 5 to 8 percent by weight of the composition of a calcium aluminate cement;
(c) 0;1 to 3,0 percent by weight of the composition of suitable dispersant; and (d) the balance by weight of the composition of a hard refractory oxide aggregate having a particle size distribution such that at least q.5 percent by weight of the particles are lmm or greater in size.
The composition of the invention is adapted to be mixed with water to form a composition of sufficient plasticity for application to a surface to form a refractory lining.
According to another aspect of the invention, there is provided a method of forming a refractory lining; from a refractory composition on a surface which includes the steps of:
(i) locating means for supporting the refractory composition in place, such as studs, a metallic mesh, e.g. hexmesh, or S-bar anchors, on the surface;
(ii) mixing the refractory composition comprising:
(a) 6 to 8 percent by weight of the composition of a volatilised silica;
-j-(b) 5 to 8 percent by weight of the composition of a calcium aluminate cement:
(c) 0,1 to ,3,0 percent by weight of the composition of a suitable dispersant: and (d) the balance by weight of the composition of a hard refractory oxide aggregate having a particle size distribution such that at least :~~ percent by weight of the particles are lmm or greater in size.
with water to form a mixture of suitable plasticity: and (iii) applying to the surface the mixture of step (ii) to form the lining.
DESCRIPTION OF PREFERRED EMBODIMENTS
The refractory composition of the invention comprises four components.
The first component of the composition is 6 to 8 percent by weight of the composition of a volatilised silica. The volatilised silica is preferably that produced as a waste by-product from silicon smelters or the like.
The second component of the composition is 5 to 8 percent by weight of the composition of a calcium. aluminate cement. An example of a suitable calcium aluminate cement is Secar %1 which is a proprietary product of Lafarge.
The third component of the composition is 0,1 to 3,0 percent by weight of the composition of a suitable dispersant. Suitable dispersants include a sodium polyphosphate or a sodium silicate.
The fourth component of the composition is a hard refractory * trade-mark oxide aggregate. The aggregate may, for example, tabular alumina, fused alumina or natural corundu~-~. The aggregate must have a particle size distribution such that at least 45 percent by weight of the particles are lmm or g-.reater in size. The maximum particle size of the aggregate will- depend on the method of application of the composition to a surface to form a refractory lining. For example, when hexme~sh is used to support the refractory composition in place, then the maximum particle size will be between 6mm and 8mm. However, when S-bar anchors are used, the maximum particle size may be greater, e.g. 12 to 20mm. It has been found tha t a composition which has an aggregate wherein at least q.$ percent of the particles have a particle size of 1mm or greater provides much better abrasion resistance than a composition with an aggregate having a smaller particle size.
The composition of the invention is designed to be mixed with a suitable percentage of water, e.g. about 3,5 to q.,5 percent by weight, to form a mixture which may be applied to a surface to form a refractory lining.
The second aspect of the invention is a method of forming a refractory lining using the' refractory composition of the invention. This method includes the steps of locating means for supporting the refractory composition in p7_ace, such as studs, a metallic mesh such as hexmesh, or S-bar anchors, on the surface to be protected, and then applying to the surface the refractory composition mixed with water, which may bcs applied by means of trowelling, ramming or hand-placing, to form the lining.
Examples of the refractory composition of 'the invention will now be given. In the examples, all percentages are given by weight.
Various compositions of the invention were formed as dry mixes and these are set out in Examples 1A, 1B, 2A, 2B, 3A, 3B 4A and 4B below. Each of these compositions was mixed with a percentage of water, as set out in Table 1 to form a mixture for use in _7_ forming a refractory lining. The mixtures, after drying at X50°C. were tested for their bulk density and for their cold crushing strength. The cold crushing strength test was performed on sample cubes 76 x 76 x 76mm in sire, prepared by hand-placing.
the mixture in a mould, without ramming or vibration. The results of these tests are also set out in. Table 1.
cwAUnTC 7 A
- 6mm graded tabular alumina 86,75 %
Volatilised silica 6,5 %
6~5 %
Secar 71 Dispersant 0,25 %
Lw A 1lT)T C t R
- 6mm graded tabular alumina 85,0 Volatilised silica 6,5 %
Secar 71* 6,5 Dispersant 2,0 L'Y A uDT Ti' 7 A
6mm graded tabular alumina 87,25 %
Volatilised silica 6,5 %
5,0 Secar 71 Dispersant 1,25 %
L'YAUDT Ti' 7R
6mm graded tabular alumina 88,38 Volatilised silica 6,5 Secar '71 ~ 5, 0 Dispersant 0,12 * trade-mark _g-- 6mm graded tabular alumina 83,5 Volatilised silica 6,5 Secar 71 8,0 Dispersant 2,0 ExAMPLE 3s - 6mm graded tabular alumina 85,0 Volatilised silica 6,5 Secar 71 8~0 Dispersant 0,5 cv w vnT z~ w ~
- 6mm graded tabular alumina81,0 0 Volatilised silica 8,0 Secar 7I 8,0 Dispersant 3,0 - 6mm graded tabular alumina 8 3,8 Volatilised silica 8,0 0 Secar 71~ 8~0 Dispersant 0,2 * trade-mask T A B 1. E 1 Example No lA ~ 1B ~ 2A ~ 2B 1 3A ~ 3B ~ øA ~ Q.B
Water Addition % ~ 4,5 I4,5 I3,5 ~3,5 I4.,5 I4,0 ~5,0 I4,5 Bulk Density g/cm3 ~ 2,952,9613,05~3,12I2,95I2,97~2,90I2,91 Cold Crushing Strength MPa ~ 120 1140 1120 1120 1180 1190 1115 1110 I
The comparative erosion resistance of the compositions of Examples lA, 1B, 2A, 2B, 3A, 3B, after mixture with water as set out in Table 1, as well as of certain known products was tested and the results are set out in Table 2 below.
Material ~ Average mm Eroded Plasticised Tabular Alumina Castable 1200 Resco-aA-22 1000 Low Cement, Sintered Alumina Ball Mix (HICAST 90BR)~ 300 214 ' 2a 3A I Less than 200 Less than 50/ Chamotte Mix Balance Corundum ( S5~ Andalusite Mix Balance Corundum ~
30~ Natural Corundum 30~ Andalusite Mie. . ~ 265 Balance Corundum * trade-mark From these results, it can be seen that th.e compositions of the invention have a much better abrasion or erosion resistance than previously known refractory compositions. 'thus, the main advantage of the composition of the invention is its superior abrasion resistance, in relation to its cost.
Claims (2)
1. A method of forming a plastic refractory lining from a refractory composition on a surface includes the steps of:
(i) locating means for supporting the refractory composition in place on the surface;
(ii) mixing the refractory composition comprising;
(a) 6 to 8% by weight of the composition of a volatilized silica;
(b) 5 to 8% by weight of the composition of a calcium aluminate cement;
(c) 0,1 to 3,0% by weight of the composition of a dispersant; and (d) the balance by weight of the composition of a hard refractory oxide aggregate having a particle size distribution such that at least 45% by weight of the particles are 1 mm or greater in size, with 3,5 to 4,5% by weight of the composition of water to form a mixture of suitable plasticity; and (iii) applying to the surface the mixture of step (ii) to form the lining.
(i) locating means for supporting the refractory composition in place on the surface;
(ii) mixing the refractory composition comprising;
(a) 6 to 8% by weight of the composition of a volatilized silica;
(b) 5 to 8% by weight of the composition of a calcium aluminate cement;
(c) 0,1 to 3,0% by weight of the composition of a dispersant; and (d) the balance by weight of the composition of a hard refractory oxide aggregate having a particle size distribution such that at least 45% by weight of the particles are 1 mm or greater in size, with 3,5 to 4,5% by weight of the composition of water to form a mixture of suitable plasticity; and (iii) applying to the surface the mixture of step (ii) to form the lining.
2. A method according to claim 1 wherein in step (I) the means for supporting the refractory composition in place is selected from studs, a metallic mesh and S-bar anchors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2024106 CA2024106C (en) | 1990-08-28 | 1990-08-28 | Refractory composition and use thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2024106 CA2024106C (en) | 1990-08-28 | 1990-08-28 | Refractory composition and use thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2024106A1 CA2024106A1 (en) | 1992-03-01 |
| CA2024106C true CA2024106C (en) | 2001-08-14 |
Family
ID=4145833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2024106 Expired - Fee Related CA2024106C (en) | 1990-08-28 | 1990-08-28 | Refractory composition and use thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2024106C (en) |
-
1990
- 1990-08-28 CA CA 2024106 patent/CA2024106C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2024106A1 (en) | 1992-03-01 |
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| EEER | Examination request | ||
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