JPS61295277A - Abrasion resistant refractory composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to refractory compositions characterized by a high degree of abrasion resistance, and in particular to such compositions which can be used as refractory caste pull.

Prior Art Fire resistant caster pull is a hydraulic composition. They consist of granular refractory aggregate and a chemical binder. Fire-resistant castapul can be transported in dry form, mixed with water to the required consistency and then poured, packed or cast in place like concrete, applied here or sprayed with an air gun. . Refractory castapulle is strongly cured by water at room temperature and maintains excellent strength as the temperature increases until the required ceramic bond is achieved. Caster pull is an irregularly shaped furnace lining,
Particularly suitable for repairing brickwork and for casting special shapes that are urgently needed. A large number of castapule compositions are known, each of which has different properties making it useful for a variety of applications.

One such application is the use of refractory caster pull to line transfer lines used in fluid catalytic crackers used in petrochemical processes. In such equipment, the highly abrasive catalyst moves at high speeds, resulting in extremely erosive pores in the b-catalytic cracker. In such equipment, abrasion-resistant linings were initially constructed from phosphate-bonded refractories, which required extensive fixing and hand compaction to install. To reduce the cost of installing objects, the refining industry has begun using caster pulls, where stainless steel 7 fibers are added in-situ, where the fixation to the metal 7 L is less extensive and can be poured relatively quickly.

Based on the above, it was desired that the installation time and cost would be improved, but the abrasion resistance would be improved.

b″-desired.

Abrasion resistant linings for petrochemical vessels are generally chemically bonded or cement bonded refractory compositions. Abrasion resistance is usually obtained through the use of strong, dense refractory particles, such as calcined fireclay, and a strong binder consisting of aluminum orthophosphate or calcium aluminate cement. In the case of cement, a wear-resistant bond is obtained by using a combination of high amounts of cement or fumed silica, an amount of cement below 10%, and a surfactant that makes it flowable with low moisture. Density is improved by casting with less moisture, resulting in a highly wear-resistant bond with less cement.

As installations seek to further save costs, fluid catalytic cracker operators have started casting on larger sections of the transfer line, eliminating assembly of many of the smaller sections. The refractory caster pull used in the transfer line was made of relatively fast-setting cement and did not remain fluid long enough for use in such applications. Refractory manufacturers have rebalanced their abrasion resistant castapulles and incorporated casting grade cement to extend pot life. Although these products provided the required flow properties and pot life, the strength and abrasion resistance were often lower than similar mixtures containing conventional calcium aluminate cements.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a refractory composition characterized by good flow properties and a relatively long pot life, with improved density strength and abrasion resistance. This purpose is to provide 0.5-
5 wt% volatile silica, 6.0-15oO wt% -6
A refractory composition is achieved consisting of 5 mesh alumina, 10-40 iit% calcium aluminate cement and the balance a refractory aggregate selected from the group consisting of silica, alumina or fireclay.

When refractory castapul compositions are used in highly abrasive environments, castapulle b''--excellent abrasion resistance is required.Furthermore, lines of relatively large parts, such as fluid catalytic cracking, are required. The caster pull must have good flowability and a relatively long pot life so that it can be installed in the lining of transfer lines used in equipment.

A first series of formulations was prepared (see Table 1 below). In the various formulations, all percentages are by weight unless otherwise specified. This series of formulations increases the fine alumina content in fireclay caster pull from 0 to 15
This shows the effect when increasing by %. As can be seen, the density, strength and abrasion resistance improve as the alumina content increases. Alumina content? The improvement in wear resistance from 8,4 CC loss in the formulation with 15% alumina content to 7,0(n loss in the formulation with 15% alumina content was relatively good before the addition of alumina). This is significant for wear-resistant types of refractories.Fine synthetic alumina is used in the refractory industry to improve the fire resistance of refractory joints and to ensure that refractories have a suitable particle size distribution. It is commonly used as a fine substance to ensure that

A second series of formulations was made to determine the effect of adding 0-5% volatile silica to the same abrasion resistant fireclay caster pull. With the addition of 0.65% and 2% volatile silica, density, strength and abrasion resistance were improved. At 6% and 5% volatile silica levels, the formulation became viscous and did not flow as before. Density and strength deterioratedb
-1 Improved abrasion resistance was retained. Volatile silica is a submicron amorphous byproduct of ferrosilicon production and is a well-known refractory raw material. It is primarily used as a source of ultrafine particles, as a source of reactive silica and as an additive to improve fluidity. As shown in Table 0, only small amounts of solder can be used in cement-containing formulations without adversely affecting the flow properties.

A third series of formulations was made to determine the effect of adding volatile silica to fireclay containing fine alumina. Density 1 strength and abrasion resistance improve as alumina is replaced by up to 2% silica. At 5% strength, the formulation becomes viscous and has poor flowability. However, wear resistance continues to improve.

Formulation P has remarkable abrasion resistance, while Formulation N has
The -1 composition is preferred because it has excellent fluidity, which is a necessary property when used as a refractory caster pull for relatively large-scale applications. The synergistic effect of using volatile silica and fine alumina together is noteworthy. The abrasion resistance of Formulations N and P is superior to any of the formulations shown in Tables I and 1 using each material separately.

A fourth series of formulations was made. Each formulation was formulated according to the invention. Each formulation contains 2% volatile silica and 8%
It contained three types of fine alumina. All four formulations had high cold crush strength and significant abrasion resistance. A-17 and A-15 reactive aluminas are sintered corundum (alpha alumina) with almost all s being 1 fine.
Consists of crystals. These have a large surface area and a small crystal b1, so they are thermally reactive. That is, they are further sintered or reacted with other compounds at relatively low temperatures. T-
61 plate alumina is also essentially 100% corundum crystal, but when this material is smoldered to high temperatures,
Rough plate-like non-reactive crystals formed. A-2 calcined alumina is about 90% corundum crystals and 10% beta alumina (Na2O" 11 At203 ) crystals. The thermal reactivity of A-2 calcined alumina is between platelet alumina and reactive alumina. Table ■ shows various properties of these aluminas.

A further main formulation was made according to the invention with 1% volatilization strength and 9% fine alumina.

Formulation T is based on calcined fireclay particles. This woodcutter formulation has been used where excellent abrasion resistance is required. Formulation U is based on fused silica particles. This formulation has been used where a combination of good abrasion resistance and low thermal conductivity is required. Formulation V is based on coarse platelet alumina and exhibits ultimate strength and abrasion resistance. Platy alumina is more than ten times more expensive than calcined fireclay, so moderate property improvements do not justify the high cost. The three formulations attempt to illustrate the types of base material particles that can be used ranging from 100% 7Il strength, to approximately 50% silica and 45% alumina fireclay, to 100% alumina. be. various high alumina particles, with alumina content between fireclay and platy alumina;
Examples include calcined bauxite kaolin, calcined bauxite, kyanite and andalusite, which may also be satisfactorily used in the present invention. Additionally, non-aluminum non-licades such as silicon carbide, silicon nitride or any acidic aggregates are also satisfactory.

The following series of formulations demonstrate the effect of varying cement content. As can be seen, as the cement was increased from 10% to 40%, the cold crush strength and aging resistance generally improved.

Table ■ Evaluation of cement content Compound name: wxy Compound: Calcined Super Duty Free 70% 50% 50%
Reactive Alumina 8 8 8 Volatile Silica 2 2 2 CA-25C Casting 10 1 40 Grade Cement Casting Water Required, %: 8.0 8.0
9.0 High Density, pCf After drying at 250″F: 138 151
After heating at 1511500″F for 5 hours 156 14)
14) Abrasion Test (A S TM C-704) Example Last σ) A series of formulations were tested to establish upper and lower limits for volatile silica and fine alumina content, and to provide a good combination of flow and physical properties. Selected preferred formulations are illustrated.

Table■ Compound name: Z X AA
Formulation: Volatile Silica 0.525 Casting Water Required, %: 8.4 8.0 7.6 Casting Properties 20. Formulations containing 5% volatilization strength have satisfactory flow properties during casting, but 1
Formulations containing 2% volatile silica are not as good. The formulation containing 5% volatile silica had poor flow properties, was difficult to handle due to its viscosity, and dried rapidly during casting.

Bulk density, pcf After drying at 250″F’ 154 151
After heating at 1491500″F’ for 5 hours 145 14
) 14) Abrasion Test (ASTMC-70-4) Effects of the Invention The composition of the present invention can be used as a refractory caster pull for applications requiring a high degree of abrasion resistance, excellent flowability and long pot life. It provides:

Such properties are required for the lining of the transfer line of a fluid catalytic cracker.

All percentages herein are by weight-t% and all mesh sizes were measured according to the Tyler standard series.

Although only calcined clay was used to produce the refractory aggregate for each formulation, other refractory aggregates such as silica and alumina as well as other acidic aggregates could also be used! l'-Can be done.

Although preferred embodiments of the invention have been described, the invention is not intended to be limited thereto, but may be otherwise embodied within the scope of the claims.

(5 other people)

Claims (8)

[Claims] (1) 0.5-5% by weight volatile silica, 3.0-15% by weight -65 mesh alumina, 10-40% by weight calcium aluminate cement and the remainder refractory aggregate;
A fireproof composition consisting of: (2) A composition according to claim (1), comprising the addition of formulation water for use of the composition as a refractory castapulle characterized by a relatively high degree of abrasion resistance. (3) The refractory aggregate is selected from the group consisting of silica, alumina, and fireclay.
The composition described in item 1). (4) The composition of claim (3), wherein the refractory aggregate comprises 4.5 to 12% by weight of -65 mesh calcined clay. (5) The composition of claim (4), wherein the -65 mesh alumina is substantially 8% by weight. (6) The composition according to claim (5), wherein the volatile silica is substantially 2% by weight. (7) The composition of claim 1, wherein the -65 mesh alumina is substantially 8% by weight. (8) The composition of claim (1), wherein the volatile silica is substantially 2% by weight.