JPH02263767A - Prepared unshaped refractory - Google Patents

Abstract

PURPOSE:To enhance both casting workability and resistance to explosion at a time of preheating and drying by blending an oxycarboxylic acid and/or its carboxylate with a composition consisting of refractory aggregate, refractory superfine powder, a dispersant and a curing agent. CONSTITUTION:(D) 0.3 to 3wt.% oxycarboxylic acid (e.g. glycolic acid) and/or its carboxylate (e.g. sodium glycollate) is blended with a composition consisting of (A) acidic, neutral or basic refractory aggregate (e.g. electromelted alumina aggregate) regulated in particle size in accordance with necessity, (B) 5 to 15wt.% refractory superfine powder (e.g. alumina ultrafine powder) having <=10mum preferably <=1mum particle diameter as a binder, (C) a dispersant (e.g. sulfonic acid-based dispersant) and (D) 1 to 5wt.% curing agent (e.g. alumina cement).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a monolithic refractory with improved explosion resistance during preheating and drying, and is used as a lining for various furnaces.

Used for external refining vessels, refining lances, and various furnace covers.

BACKGROUND OF THE INVENTION In recent years, refractory castables have made great strides, with the advent of low cement castables. That is 1
By fluidizing ultrafine powder of 0 g, m or less, preferably Ip, m or less under the peptizing action of a dispersant, a dense construction body can be obtained with a low amount of water. As the name suggests, a small amount of cement is added, and after the ultrafine powder is deflocculated, the cement acts as a coagulant (hardening agent) over time. It is something.

By the way, because low cement castable is dense, it is extremely difficult for water to evaporate during the drying stage after curing.
Rapid drying over a short period of time has the disadvantage that explosions are likely to occur due to the door pressure.

Improving explosion resistance is therefore an important issue for low cement castables, and various improvement techniques have been disclosed so far. A disclosed example is a technology that attempts to prevent explosions due to water consumption and heat generation by adding AI powder and causing it to react with alkaline water (for example, Japanese Patent Application Laid-Open No. 53-1999)
66917), or organic or inorganic U&
A method of adding males (for example, Japanese Patent Application Laid-Open No. 54-11841)
2, Japanese Unexamined Patent Publication No. 59-190276), etc. However, the former has the risk of causing an explosion caused by hydrogen gas, and the latter has the problem that it is difficult to uniformly disperse the fibers.

Furthermore, JP-A-62-100483 states that addition of basic aluminum lactate is effective;
This basic aluminum lactate is limited to those having a specific composition of Al2O3/milk liquor (molar ratio) of 0.3 to 2.0, which is obtained by reacting a water-soluble aluminum salt with a carbonate. Furthermore, it has been found that when the amount added is increased to enhance the explosion prevention effect, the fluidity of pouring operations deteriorates.

As a result of intensive research, the present inventors have discovered that oxycarboxylic acids and their carboxylic acid salts have a wide range of explosion-preventing effects, and have completed the present invention.

Problems to be Solved by the Invention The present invention provides a monolithic refractory, particularly a low cement castable, which generates extremely little flammable gas during construction, curing, and drying, and which has extremely excellent explosion resistance when drying. This is what we provide.

Means for Solving the Problems In order to achieve the above-mentioned problems, an uninvented monolithic refractory is produced by adding oxycarboxylic acid and/or One or more of these carboxylic acid salts are added in an amount of 0.3 to 3.0% by weight (hereinafter all % by weight).

Ordinary low cement castable is made by adding one or more types of acidic, neutral, basic, etc. refractory aggregates that have been traditionally used in the refractory industry, with the particle size adjusted appropriately, and clay as a binder. 5 to 1 or more types of refractory Itfl fine powder of particles 1'A I Og m or less, preferably 1 #Lm or less, such as silica alumina, chromium, titania, etc.
5% 1 phosphate, carboxylate, sulfonate, etc. as a dispersant, and alumina cement 1-5 as a hardening agent.
% was added and mixed.

Specific examples of oxycarboxylic acids used in the present invention include glycolic acid, lactic acid, oxybutyric acid, and tartaric acid. Further, examples of the carboxylate include salts of alkali metals such as lithium, sodium, and potassium. Although alkaline earth metal salts are not ineffective in preventing explosions, they are inferior to alkali metal salts in that they are less effective and have poor fluidity during pouring work.

In terms of ease of handling, powdered products such as glycolic acid, sodium glycolate, lithium lactate, oxybutyric acid, tartaric acid, and sodium tartrate are convenient. However, lactic acid,
Even liquid materials such as sodium lactate may be pulverized, and the effect of the invention will not be impaired even if the pulverization treatment is performed.

The content of one or more of oxycarboxylic acids and/or alkali metal salts thereof is preferably 0.3 to 3%.
．． If it is less than 3%, the explosion prevention effect will not be sufficient;
This is because the strength decreases significantly if the strength is exceeded.

The present inventors added lithium lactate to the basic formulation shown in Table 1 and conducted explosion tests and strength measurements. After kneading the test piece with the minimum amount of water that would give good fluidity,
Cast into a mold of 0X40XL60mm, temperature 10°
C is the frame after 24 hours of curing. The explosion test was conducted in the explosion resistance test furnace shown in Figure 5.
The sample (3) was inserted into a furnace maintained at a predetermined temperature using a thermocouple (2) for 20 minutes, and the presence or absence of an explosion was examined. The holding temperature is set in 100°C increments, and the maximum temperature that does not explode is indicated as the explosion-proof temperature.

The experimental results are shown in Table 2, and it can be seen that the effect of improving the explosive property is observed when the amount of lithium lactate added is 0.3%, and becomes noticeable when the amount of lithium lactate added is 1% or more. However, if it exceeds 3%, not only will the curing time become longer, but also the bending strength after drying at 110"C and firing at 1450" for 3 hours will be greatly reduced, which is undesirable.

Such a tendency is also seen with other oxycarboxylic acids or their alkali salts. In addition, as can be seen from the fact that there is no increase in the temperature of the added water, in the case of lithium lactate, even if the amount added increases, the fluidity does not deteriorate.

(Leaving space below) Examples in which various oxycarboxylic acids and/or their alkali tl were added to the basic formulation in Table 1, and as comparative examples, examples in which metal aluminum powder was added to the same basic formulation, or oxycarboxylic acid was added to the basic formulation. Table 3 shows the #explosiveness test results for examples using alkaline earth salts as metal salts of acids.
The powdered lactic acid of Example 6 and the powdered sodium lactate of Example 7 were prepared by adding liquid lactic acid or sodium lactate to calcium lactate in a ratio of 1!
, 1.

(The following is a blank space) It can be seen that all of the examples have explosion prevention effects comparable to the addition of metallic aluminum powder, which is currently widely adopted as an explosion prevention technology among those skilled in the art. Examples 6 and 7 show that this effect is not impaired even if the liquid material is pulverized to make it easier to handle.

Effects of the Invention As described above, it has been found that the low cement castable using the present invention has good pouring workability and extremely excellent explosion resistance.

[Brief explanation of drawings]

The drawing is an explanatory diagram of the explosion resistance test furnace.

Claims (2)

[Claims] 1. 0.3 to 3% by weight of one or more of oxycarboxylic acids and/or carboxylic acid salts thereof is added to a composition consisting essentially of refractory aggregate, refractory ultrafine powder, dispersant, and curing agent. A monolithic refractory characterized by the addition of additives. 2. Claim 1, wherein the carboxylic acid salt is an alkali metal salt.
The listed monolithic refractories.