KR100373703B1 - Silica Refractory Composition and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a silica-based refractory composition used for hot repairing damaged parts of an industrial furnace refractory made of silicate or silicate-based refractory, and has a particle size of 38 to 86% by weight of a large silica powder. Is added in an amount of 10% to 30% by weight, 2% to 12% by weight of the small-size wollastonite powder and the lithium mineral powder are added together, and 2% to 20% by weight of very small aluminum powder It is further provided to provide a silica-based refractory composition.

Description

Silica Refractory Composition and Manufacturing Method Thereof

The present invention relates to a refractory composition used in the ceramic welding method, and more particularly, to a silica-based refractory composition used to hot repair the damaged part of the industrial furnace refractory made of silicate or silicate-based refractory, and a manufacturing method thereof. .

The coke furnace that cokes coke in the steel industry is a large furnace made of siliceous refractory, which is a facility that operates continuously for about 10 to 50 years.

Such coke furnaces cost hundreds of billions to construct one coke furnace, and many studies have been conducted on how to repair and use them without reconstruction because coke furnaces that are disposed of after use can cause environmental problems. .

Particularly, coke ovens are made of siliceous refractory based mainly on tridymite silica due to the operation conditions in which coal is charged into the carbonization chamber before and after 1350 ° C. for a long time, and the operation is repeated for several decades. Bricks have been used.

Due to such a harsh operating environment, siliceous refractory materials are repeatedly damaged by carburizing, thermal shock, abrasion, and the like, and various refractory repair techniques have been developed to repair damaged refractory materials.

Such repair techniques include partial removal of damaged refractories, reconstruction of the removed parts with new refractories, patching with plastic refractory materials, a method of spraying water and refractory materials mixed together, and , Thermal spraying and repair of powdered thermal spray materials with flame resistance, and ceramic welding.

Among the conventional refractory repair methods, the rebuilding method is the best repair method because it can be rebuilt based on accurate design, but it takes too much time to repair because it needs to be reheated after several months after cooling the furnace body. none. Therefore, it is not used well except in case of damage caused by a large accident such as partial collapse.

The method of spraying and bonding water and refractory materials and patching method gives thermal shock to the furnace refractories that are operated before and after 1350 ° C, which may cause problems in the refractory parts of damaged areas as well, and it is difficult to obtain excellent characteristics of the repaired body. Therefore, it is mainly applied to coke ovens with a relatively short operation period after construction, and are not used well for old furnaces with long operating years.

The flame spray repair method has been developed since the 1970s and is widely used in the world. It is a high-speed flame at high temperature of 2000 ~ 2500 ℃ using flammable fuel such as petroleum, coke powder, LPG and combustion gas such as oxygen. It is a technique of spraying the refractory powder together while adhering to the refractory damaged area in the molten or semi-melt state. This method has a limitation in applying as a coke oven repairing technique because the repairing apparatus is complicated, large, and expensive.

In addition, the ceramic welding method, which is similar to the flame spraying repair method, is capable of welding and welding refractory damaged areas by oxidizing and heating the metal powder contained in the refractory composition without forming a spark, so that the repair device is simple and there is no fuel cost problem. It is attracting attention as a hot repair method.

Conventional fire resistant compositions used in such ceramic welding methods include the following.

1. A refractory composed of 87 wt% silica powder, 12 wt% metal silicon powder and 1 wt% metal aluminum powder (Korean Patent 91-6896).

2. Silicon carbide-Metal silicon-Metal aluminum type, Silicon carbide-Metal silicon-Metal aluminum-Magnesia type, Silica-Metal silicon-Metal aluminum-Magnesia type, Silica-Wollastonite-Metal silicon-Metal aluminum type Refractory composition (Japanese patent) Publication No. Hei 5-201772).

3. Refractories with small amounts of wollastonite powder added in 1 or 2.

When the furnace body refractory is repaired by ceramic welding with the refractory having such a composition, the cross section of the construction body is shown in FIG.

In Fig. 1, reference numeral 11 denotes silica particles and reference numeral 13 denotes a known phase. And A represents the construction layer, B represents the interface layer between the construction layer and the base material refractory, and C represents the base material refractory layer.

As shown in FIG. 1, all of the conventional refractory compositions 1, 2, or 3 are partially repaired due to partial separation 15 or crack 17 at the interface layer due to the difference in expansion and contraction characteristics between the base material refractory body and the construction body. There is a problem of shortening the life of the old furnace body.

The separation (15) or crack (17) in the interfacial layer occurs in the case of coke oven for a long time use of the base material refractory silicate refractories, carburizing and mineral phase changes and texture changes resulting in hot shrinkage, expansion characteristics While this is stabilized, the construction layer by ceramic welding starts to shrink and expand according to new materials.

The above-mentioned hot repair method or the conventional refractory composition used therefor is used not only for the coke furnace but also for the repair of glass melting furnaces, incinerators or hot stoves using silica or silicate refractory materials, even when used in such furnaces. Separation 15 or crack 17 between the ceramic and the ceramic construction layer occurs as shown in FIG. 1.

The present invention has been made in order to solve such a problem, the object of the present invention is to prevent the defects in the structure generated inside the construction by the instantaneous temperature change or configuration change after the construction of the refractory repair by the ceramic welding method It is to provide a silica-based refractory composition containing a lithium-based mineral that can control the surface roughness and a method of manufacturing the same.

1 is a cross-sectional view of a construction obtained by repairing ceramic welding with a silica-based refractory composition.

2 is a cross-sectional view of a ceramic weld repaired body with a silica-based fireproof composition according to the present invention.

In order to achieve the above object, the present invention, in the refractory used to hot repair the damaged part of the industrial furnace refractory made of siliceous or silicate-based refractory, the silica particles with a large particle size of 38% to 86% by weight 10 to 30% by weight of small-size metal silicon powder is added, 2 to 12% by weight of small-size wollastonite powder and spodumene powder are added together, and very small-size alumina powder To provide a silica-based refractory composition by adding 2 to 20% by weight.

In the present invention, the spodumene powder added together with the wollastonite powder may be used in place of the petalite powder.

The main characteristics of the silica-based refractory composition according to the present invention include wollastonite which gives the melt viscosity of the workpieces grown during ceramic welding repair and additives that suppress the expansion during use of the workpiece after the welding repair is finished, namely spodumene or lithium-based mineral. It is to add a small amount of petalite in combination.

The silica-based refractory composition according to the present invention is grown and welded on the refractory surface by rapid oxidation and exothermic reaction of the added metal silicon or aluminum powder when spraying the damaged refractory site using oxygen as a gas for powder transportation and oxidation.

In addition, the silica-based refractory composition according to the present invention can stabilize the workability at the time of welding repair and repair work structure after welding repair compared to the conventional powder material, so that the hot repair of the damaged part of the siliceous refractory in the furnace body by the ceramic welding method. Suitable powder material.

Another important feature of the silica-based refractory composition according to the present invention is that it exhibits proper melt viscosity during the process of adhesion growth on the refractory damage site during repair and construction, thereby improving adhesion and construction characteristics, The adhesion state at the base material refractory interface is such that defects such as separation and cracking do not occur as shown in FIG. 2.

Important features of the present invention as described above are due to the composition of the silica-based refractory and the method of manufacturing the characteristics of the manufacturing method is first kneaded sufficiently by adding wollastonite powder and spodumene powder or wollastonite powder and petalite powder to silica powder Next, the metal silicon powder is added thereto to knead sufficiently, and finally, the aluminum powder is further added to knead sequentially.

Hereinafter, the present invention will be described in detail through examples and comparative examples shown in Table 1. The embodiments to be described below are for illustrating the present invention, and thus the present invention is not limited only to these examples.

Example Comparative example One 2 3 4 5 6 7 8 9 10 11 12 Silica ¹⁾ 86 70 65 65 50 38 88 83 69 57 45 36 Metal Silicon Powder ²⁾ 10 10 25 20 25 30 10 9 15 20 25 32 Wollastonite ³⁾ One 2 2 3 5 4 - 3 10 6 4 6 Spodumene ⁴⁾ One 8 - 4 - - - - - 7 4 - Petalite ⁵⁾ - - 3 - 5 8 - 3.5 - - - 6 Aluminum powder ⁶⁾ 2 10 5 8 15 20 2 1.5 6 10 22 20 Thermal Spraying MaterialsFI ⁷⁾ 68 54 56 54 49 43 68 65 51 47 45 42 Construction Adhesion Rate (%) 83 97 90 95 98 98 77 72 91 94 97 96 Porosity (%) 9.4 5.4 6.1 4.9 8.6 9.2 10.2 14.7 8.5 13.4 12.1 10.4 Refractoriness ⁸⁾ 29 27 28 27 27 26 29 28 27 23 27 26 Organizational Status ⁹⁾ △ ○ ○ ○ ○ ○ × △ × ○ △ △

(Here; 1) silica: silica powder with a particle size of 1 mm or less, 2) metal silicon powder: metal silicon powder with a particle size of 0.074 mm or less, 3) wollastonite: natural wollastonite powder with a particle size of 0.074 mm or less, 4) spodumene: particle size 0.074 spodumene powders up to mm, 5) Petalite: Petalite powder up to 0.074 mm in particle size, 6) Aluminum powder; Aluminum powder with a particle size of 0.044 mm or less, 7) spray material FI: Flowability Index, 8) fire resistance: SK number, 9) texture state; Crack state generated inside the body obtained by welding under the conditions of 50kg / hr injection rate, 80Nm ³ / hr oxygen, and 20cm injection distance (○: no crack, △: slight crack, ×: high crack)

Experimental results shown in Table 1, the refractory powder prepared according to the present invention combined the oxygen transport and oxygen for oxygen to the flow rate to 80Nm ³ / hr and the injection speed is 50Kg / hr and the injection distance is 20 ℃ 1000 ℃ This is the result when welding to the siliceous refractory surface heated with.

First, the effects of addition of lithium-based mineral indudumen and petalite, which play an important role in the silica-based refractory composition of the present invention, will be described first.

When the wollastonite powder and the lithium-based mineral are not added as in Comparative Example 7, the fire resistance of the construction body is maintained to be somewhat high, but it can be seen that the adhesion rate during the thermal spraying is poor and the porosity is high.

In addition, when the total amount of wollastonite powder and the lithium-based mineral is more than 12% by weight, the fluidity index (FI) of the refractory powder decreases due to the increase of the additives having a small particle size as in Comparative Example 10, making it difficult to transport the powder during welding repair. Although the adhesion rate is slightly increased, it is excessively melted and the porosity is increased, resulting in a failure of the construction body.

If only one type of wollastonite powder is added as in Comparative Example 9, the adhesion rate and the porosity of the construction body may be rather good, but defects in the structure of FIG. 1 occur.

On the other hand, although not shown in the examples, when only one of spodumene or petalite is added without adding the wollastonite powder, it is difficult to use because there is no melt viscosity at the time of welding repair.

Therefore, lithium-based minerals are preferably added together with wollastonite powder to increase fluidity, and the amount of wollastonite powder or spodumene powder or wollastonite powder and petalite powder is preferably 2 to 12% by weight. .

When preparing silica-based refractory powder by adding wollastonite powder and spodumene powder or wollastonite powder and petalite powder, the order of addition, blending, and kneading of each additive is important.

Industrially, it would be economical to knead and knead and pack all the additive raw materials at once, but even if it is a refractory having the same composition, the difference in the order of mixing and kneading causes a great difference in the performance of the construction during welding repair.

Therefore, the blending sequence of the silica-based refractory powder according to the present embodiment is first kneaded sufficiently by adding wollastonite powder and spodumene powder or wollastonite powder and petalite powder to silica powder, and then adding metal silicon powder to the mixture to sufficiently knead and continue. The raw materials were blended by adding aluminum powder and kneading sequentially.

Mixing the additive raw materials in this order is performed by sequential oxidation and heating of aluminum powder and metal silicon powder, which first softens and melts the wollastonite powder and the spodumene powder or the wollastonite powder and the petalite powder, and then the silica is softened rapidly. This is because the refractory powder mixed in this way can be distributed in a state where the oxidation reactivity of the aluminum powder and the metal silicon powder can be most enhanced.

In this embodiment, the aluminum powder plays an important role in enabling the ceramic welding by appropriately melting the additives by oxidative heating. However, the aluminum powder shows various differences in oxidation reactivity according to commercially available products. If is more than 95% can be used.

When the aluminum powder is added in less than 2% by weight, even though the aluminum powder with high purity is added, the amount of heat generated is insufficient, so that welding is not performed properly. As shown in Comparative Example 8 of Table 1, the adhesion rate is extremely bad and the porosity of the construction body is high. It becomes very high and not practical.

In addition, when added to 20% by weight or more, as in Comparative Example 11, the adhesion rate is very excellent due to excessive exothermic reaction, but due to the over-melting of the raw material, the structure of the construction is porous, the porosity is too high to be used.

Therefore, it is preferable to add 2 weight%-20 weight% of the addition amount of aluminum powder, and it is more preferable to add before and after 5 weight% for a silica refractories repair.

The metal silicon powder has a melting point of about 1400 ° C, which together with aluminum powder assists in the heat of oxidation during welding repair and gives densification of the construction. When the added amount is less than 10% by weight, as in Comparative Example 8, the amount of heat of oxidation is also insufficient. However, there is a problem that the compacted body is not properly densified, and when the added amount is more than 30% by weight, the aluminum powder having a small particle size is present in excess, which lowers the fluidity of the refractory powder itself and causes frequent pulsation in powder transportation during welding repair. This causes defects in the structure of the construction body.

Therefore, the metal silicon powder is preferably added in the range of 10% by weight to 30% by weight.

Silica powder is composed of tridymite and crystobalite phases as the main mineral phase, and plays a role in maintaining the skeleton of the construction body during ceramic application repair. It is also possible to use large particles of about 3 mm to 5 mm by speeding up the transport oxygen more than twice as fast.

When the amount of the silica powder added is 38% by weight or less, even if the amount of the other additives is adjusted, the amount of the silica particles, which are the large particles corresponding to the skeleton of the body, becomes relatively small, causing the structure of the body to be deteriorated. On the contrary, when the added amount is more than 86% by weight, on the contrary, the added amount of the other added components decreases, and thus the good structure of the coated body cannot be obtained because of poor adhesion rate and melt viscosity at the time of welding repair, or poor density of the coated body.

Therefore, it is preferable to add 38 wt% to 86 wt% of silica powder, and 65 wt% before and after considering the appropriate addition amount of aluminum powder, metal silicon powder, wollastonite powder and spodumene powder or wollastonite powder and petalite powder. It is more preferable to add.

As described above, the present invention can be repaired immediately by ceramic welding in hot without repairing the furnace body in repairing damaged parts of coke furnace, hot furnace, glass melting furnace, incinerator or heating furnace. It is a silica-based fire-resistant composition containing lithium-based minerals, which has excellent workability by using oxidation and heat reaction of aluminum powder and metal silicon powder without using combustible fuel, and has a compact structure and a uniform work body. It is not only convenient to use for welding and repairing the furnace body but also can reduce the maintenance cost of the furnace body, thus maximizing the repair effect of the furnace body.

Claims (4)

In the refractory used to hot repair the damaged part of the industrial furnace refractories constructed of silicate or silicate-based refractory, 38% by weight to 86% by weight of silica powder having a particle size of 1 mm or less; 10% to 30% by weight of metallic silicon powder having a particle size of 0.074 mm or less; 2 wt% to 12 wt% of a mixed powder in which wollastonite powder having a particle size of 0.074 mm or less and a lithium mineral are mixed; And Silica-based fire-resistant composition, characterized in that consisting of 2% by weight to 20% by weight of aluminum powder. The silica-based refractory composition according to claim 1, wherein the lithium-based mineral is any one of spodumene powder or petalite powder. The silica-based fire resistant composition according to claim 1 or 2, wherein the aluminum powder has a particle size of 0.044 mm or less. In the manufacturing method of the refractory material used for hot repairing the damaged part of industrial furnace refractory body built with a siliceous or a silicate type refractory material, 38% by weight to 86% by weight of silica powder having a particle size of 1 mm or less is added by adding 2% to 12% by weight of a mixture powder of wollastonite powder and spodumene powder or wollastonite powder and petalite powder having a particle size of 0.074 mm or less. Kneading to prepare a first blend; Preparing a second blend by sufficiently kneading by adding 10 wt% to 30 wt% of a metal silicon powder of 0.074 mm or less to the first blend; Method for producing a silica-based refractory composition comprising the step of kneading by adding 2 to 20% by weight of aluminum powder having a particle size of 0.044mm or less to the secondary blend.