JPS63319273A - Cao type unsahped refractories - Google Patents

Abstract

PURPOSE:To improve slaking resistance and to provide unshaped refractories which can be stably applied by incorporating a binder contg. water glass and bentonite, hydration retarder and water retaining material into a calcareous refractory raw material which is an essential component. CONSTITUTION:For example, a spray coating material is prepd. by using a grain-sized adjusted CaO type refractory raw material, i.e., CaO type clinker as the essential component and incorporating the binder contg. the water glass and bentonite, the hydration retarder and the water retaining material such as fiber material therein. The bentonite powder to be used as the binder has the performance to easily adsorb and retain water when the water is added to the binder at the time of application, in addition to the role of the binder. The water glass cures at ordinary temp. as a binder and contributes to an improvement in strength and the adhesion to a wall surface. The hydration retarder is essentially required to prepare the spray coating material which can be stably used when the spray coating material is rested for several hours on account of a trouble, etc., at the time of the application. Boron oxide, oxalic acid powder, etc., are used for said material. The water retaining material prevents the evaporation of even the moisture necessary for curing of the binder by the abrupt evaporation of the moisture when the spray coating material is sprayed to >=150 deg.C wall surface, thereby obviating the degradation in the adhesive strength and the formation of the porous structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to calcareous monolithic refractories such as sprayed materials.

[Prior Art] Various refractories are currently being used for the lining of steelmaking equipment to improve their durability. Recently, in the field of steel manufacturing, there has been an active movement to produce highly clean steel, and the application of CaO-based refractories for clean steel is expanding due to CaO's ability to adsorb nonmetallic inclusions in molten steel.

Although quicklime has excellent properties as a refractory, such as a high melting point of 2572°C, good spalling resistance, and low vapor pressure under reduced pressure and stability, it has extremely poor digestibility, so it is not put to practical use as a refractory. is late.

As a technique to prevent digestion (hydration), for example, CaO 95
Ca is added to the clinker surface by treatment in a CO2 atmosphere at around 0°C.
C0: + Using aggregate with a protective layer, or using CaO
Refractories hot-pressed at the eutectic liquid phase formation temperature of CaCl2 and pitch-based binder, phenol resin, etc. are also used as non-aqueous binders. Also, TiO□,
There is also a digestible clinker in which a low melting point substance such as Fe2(1+) is calcined with quicklime to form a glassy protective layer.

Conventionally, as a method of slowing down the hydration rate of quicklime, sucrose, chrycerin, oxycarboxylic acids and their salts, amino acids and their salts, caustic sorter, caustic potash, silicofluoride sorter, silicofluoride potassium, etc. have been added to quicklime. It has been made clear what will be done.

[Problems to be Solved by the Invention] However, these conventional refractories and fireproof prevention methods cannot prevent the erosion of sag, cracks, cracks, and chips that cause damage to steel-making container refractories. is insufficient. For example, a clinker whose surface is converted to CaCO3 to form a protective layer has poor digestion resistance for fine powders of 0.3 mm or less, and will disintegrate after being exposed to water in a short period of time. In addition, CaCl2 has high hygroscopicity, so it has poor workability and hot pressing is not common due to high cost. Furthermore, if the clinker, which is made of glass and forms a protective layer, has a fine powder strength of less than 0.3 mm, its resistance to digestion is similarly poor and it hydrates and disintegrates.

Furthermore, refractories using non-aqueous binders must be used with careful consideration, as their fire resistance is improved, the period before actual furnace use is limited, and pollution problems occur during use. .

Also, lime obtained by adding additives according to the conventional technology has a slower hydration rate and some improvement in its properties compared to the case without additives, but in actual construction sites, water is not added to the mixture. Methods such as kneading the mixture under pressure and spraying it (premix method), or pumping the mixture as it is, adding water in a spray nozzle, and spraying it (gun mix method) are used. Therefore, it is essential to spray the mixture quickly at the construction site, and if construction is significantly delayed due to problems, the speed of water use and the effect of the delay are small, and there is no spraying material that can be used stably.

Furthermore, as a refractory for clean steel, it goes without saying that it is desirable to have as good an effect of adsorbing nonmetallic inclusions in molten steel as possible.

Therefore, the object of the present invention is to produce a calcareous monolithic refractory that is stable up to and during construction in an actual furnace, does not undergo digestive disintegration, has high durability with practical value, and has a great clean steel effect.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and it is a refractory raw material mixture containing water glass and bentonite that has a calcareous main component and whose particle size has been adjusted. The present invention relates to a calcareous monolithic refractory containing at least a binder, a water retarder, and a water retaining material such as fiber.

The present invention will be explained below using sprayed material as an example.

First of all, CaO is a CaO refractory raw material used in the present invention.
Those with a CaCO3 protection layer formed on the surface of the quake linker, those with a CaO quake linker matrix formed on glassy material such as Fe2(1+, 5102, TlO2, etc.), or those with the CaO quake linker surface covered with silicon or fluorine resin. CaO clinkers of electrofused or calcined quality, which are commonly reprinted, may be used.

Further, it is also possible to use dolomite clinker, magnesia clinker, etc. as a part of the refractory raw material containing these as main components.

In preparation for such CaO quality quaclinker attachment materials, the thickness is prepared to be less than 1 mm, but if it becomes less than 0.3 [11 m], it will be digested in 1 to 2 weeks at 20°C and R895% or more. Therefore, the seal of the preparation must be kept completely sealed until use. Therefore preferably 0.3
11II Fine powder of 11 or less does not contain free gicaO
It is more effective to use aO.ZrO2 or CaB powder.

In the present invention, we have made extensive efforts to ensure stable construction when using CaO-based refractory materials, and as a result, we have discovered an additive that allows CaO-based sprayed refractories to perform more effectively. binder), water retarding materials, and water retaining materials.

The bonding material is often applied on-site for spray-resistant large objects, where the wall surface is at a temperature of 150°C or higher, so it hardens relatively slowly, and the density and strength of the sprayed material after spraying are high, resulting in good adhesion (adhesion) to the wall surface. A material with high strength is desired.

Therefore, it is possible to use a binder of clay and water glass, a drainage binder such as phenol resin, an aluminum phosphate binder, etc., or at least a water glass powder and bentonite powder, preferably a water glass powder. It is preferable to use sodium fluorosilicide powder as a hardening agent and anhydrous borax powder. Bentonite powder used as a binder not only acts as a binder but also has the ability to adsorb water and easily retain water when water is added during construction, and is a binder that fulfills both roles.

Additionally, water glass is a binding material that hardens at room temperature and serves as a binder to increase strength and adhesion to walls.

The content of these components is desirably about 1 to 15%, especially about 3 to 8% (weight %, the same applies hereinafter) based on the refractory raw material.

In addition, water glass powder and bentonite powder each have a
5% is best.

Furthermore, in the case of EaO sprayed refractories, they are often constructed on-site and often left unattended for several hours due to problems during construction, etc. It is preferable to use sprayed materials that can be used stably over time. A retardant is essential, and by adding boron oxide or oxalic acid powder, etc. to the refractory raw material in an amount of preferably 0.1 to 5%, the pH of the spraying formulation can be made slightly acidic. Nishite CaO+H20+ Ca(O
H)? (71 It becomes possible to suppress the hydration reaction.

Although it is possible to use lactic acid, citric acid powder, etc. as the hydration retarder, boron oxide or oxalic acid powder is preferable. If the hydration retarder is 0.1% or less,
The effect of suppressing hydration is low, and if it exceeds 5%, a gelation reaction with the water glass used as a binder will occur and it will instantly harden into a porous structure, so it is not preferable, and desirably 0.5 to 5%.
It is set at 4%.

Particularly important is the preparation of the slurry pi of the formulation by adding boron oxide or oxalic acid powder to the GaO-based spray formulation, with a pH of 7-3, preferably pH 8,
It is thought that the preparation of 5 retards the hydration of the canium, which in turn generates borate on the surface of the canium as shown below, thereby suppressing hydration.

In this way, boron oxide or oxalic acid suppresses the hydration of Can. For example, when CaO-based tempered compound boron powder is added and mixed with water, when the surface of Can is slightly hydrated. It is thought that the generated Ca(OH)2 and boron oxide chemically react to produce a borate such as Ca3(BO3)2, which covers the surface of the lime particles and suppresses subsequent hydration.

Water retaining materials are sprayed on-site and are sprayed onto walls with temperatures above 150°C, so water rapidly evaporates, and even the water needed to harden the bonding material evaporates, reducing the adhesion strength to the wall and further reducing the strength of the sprayed material. Since the structure also becomes porous, it is necessary to provide a sufficiently dense structure.

As a water-retaining material, inorganic or organic fiber materials are preferably used, and among these, asbestos, glass,
Fibers such as slag and cellulose fibers are suitable, but
Ca or Ca-9i alloy fibers can also be used. or,
Cellulose powder and the like are suitable as water retaining materials other than fibers.

It is necessary to add 1 to 5% of the water-retaining material to the CaO-based blown mixture fire material, but if it is less than 1%, the water-retaining effect will be low, and if it is more than 5%. This is because the water retention property becomes too good, the curing time increases, and the heat resistance decreases, so the optimum range is desirably 1 to 3%.

It has been recognized that the addition of fibers not only improves water retention, but also has the effect of improving adhesion to walls and preventing peeling due to cracking of the spray body.

In addition, these fibers have a diameter of 0.1 to 2000 p and a length of 1
A layer with a thickness of about 0 to 200 m is suitable. Especially diameter 0
．． A layer of 2 to 500 ml and a length of 1 m to 50 m II is optimal.

The present invention thus blends calcareous clinker or calcareous clinker treated with digestion resistance, more preferably 0.3 am or less free GaO-free CaO/ZrO2 or CaB6 as a fine powder, and further contains powdered water glass and bentonite powder as a binder. Add anhydrous borax and sodium fluorosilicide, add boron oxide or oxalic acid as a hydration retardant, add fiber to prevent rapid water evaporation during construction as a water retaining material, knead with water, and spray or nozzle. It is a sprayed material that is applied by pressure-feeding, mixing with water in a nozzle, and spraying, and has stable extinguishment resistance during use. When this sprayed material is installed and used on the lining of a steelmaking furnace, this refractory is dense and does not crack or peel even when heated rapidly.
Can be used stably. Also, the matrix of this refractory is G
It is composed of aO, GaO, ZrO2, CaB6, etc., and has high heat resistance and good corrosion resistance when it comes into contact with slag at high temperatures, so it has a high melting point.
Therefore, the penetration of slag components is extremely limited to the surface layer, which shows an excellent effect on structural spalling properties, as well as the nonmetallic inclusion removal effect of CaO (Al in steel).
It is thought that the adsorption of 2O2 was improved by the quality of CaO in the matrix.

L Example] Table 1 shows examples of the blending quality of hard spray materials.

The spraying material was mixed with water glass powder (Si0235-38%, Na2017-18%) as a binder in the formulation shown in the example.
; No. 1), anhydrous borax powder (H
3BO4, purity 88%), sodium silicofluoride powder (purity 98%), boron oxide powder (B2O2 purity 89%) as a water retardant, oxalic acid powder ((GOOH)2 purity 99%)
), asbestos fibers (diameter 0.3-10μ,
length approximately 20cm) or slag wool (analysis value 5i0235
~45%, Ca030~40%, Al2O310~20
%, Mg04~7%, diameter 2~20l, length lO~200
(2) Or bulb powder was added as cellulose powder to make a powder formulation. Water was added to this powder mixture, kneaded, and applied using a spray machine. As comparative examples, the results of a formulation without the addition of a hydration retardant and a formulation without a water retaining agent are shown.

The measurement method for each test result is as follows.

・Adhesive strength indicates the adhesive strength measured by spraying on bricks, curing, and tensile strength after drying.

・In the slaking test, after hardening and drying the sprayed material in a mold,
After being inserted into saturated steam at 120°C for 4 hours and taken out,
The hydration breakdown situation is shown.

- For the corrosion resistance test, the sprayed material was hardened in a mold in a high-frequency induction furnace, dried at 150°C for 6 hours, and then used as a test piece.

Then, a cylindrical crucible was formed with these samples and 5S-4
1 and C/S=2 synthetic slag (Ca040%, 5i02
2%, Al2O3 18%, Mg01B%, Fe2034
%, etc.) and was subjected to an erosion test at 1600°C for 4 hours, and the corrosion resistance was expressed as the maximum erosion depth (m1).

The spalling property was determined by examining the presence or absence of cracks inside the sample after the erosion test (0: absent, x present).

As a result, it was confirmed that the sprayed material containing the hydration retardant and water retaining material had good digestion resistance and high corrosion resistance.

Furthermore, when we analyzed the eroded surface of the sample after the erosion test, we found that
In the refractory of the present invention, C
A6 (CaOeAI203) and 03A (GCaOA
I203) was detected on and near the eroded surface. This indicates that the refractory of the present invention has an excellent clean steel effect (effect of adsorbing nonmetallic inclusions in steel).

[Effects of the Invention] As described above, the present invention improves the extinguishing resistance, which is the biggest drawback of CaO-based sprayed refractories, and is a monolithic refractory that can be stably constructed at construction sites, and has excellent corrosion resistance against molten metal and slag. It is a highly durable spray refractory that not only has spall resistance and adhesive properties, but also has an improved effect on removing non-metallic inclusions from steel. It can be used in a wide range of applications, mainly as lining furnace materials, and its industrial value is enormous.

Claims (8)

[Claims] (1) A CaO monolithic refractory whose main component is a calcareous refractory raw material, and which contains at least a binder containing water glass and bentonite, a hydration retardant, and a water retaining material. (2) The proportion of binder, hydration retardant and water retaining material on the outside of the refractory raw material whose main component is calcareous material is 1 to 15%, 0.1 to 5% and 1 to 5% by weight, respectively. A monolithic refractory according to claim 1. (3) The refractory according to claim 1, which contains sodium silicofluoride as a binder curing agent. (4) The refractory according to claim 3, which contains anhydrous borax as a binder component. (5) The refractory according to claim 1, wherein the hydration retarder is boron oxide and/or acid powder. (6) The refractory according to claim 5, wherein the hydration retardant is oxalic acid powder. (7) The water retaining material is fibrous. Claim 1
Refractories listed in section. (8) The fibrous water retaining material has a diameter of 0.1 to 2000μ and a length of 1
The refractory according to claim 7, which has a thickness of 0 μ to 200 mm.