JPH0124842B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a refractory for blowing an inert gas such as argon nitrogen gas into the refractory for degassing molten metal. Recently, degassing treatment has been widely used to improve the quality of steel, but the current situation is that sufficient operational effects cannot be obtained due to its poor durability. Traditionally, for degassing treatment, a porous plug was inserted into the bottom of the container and argon nitrogen gas was blown into it, but porous plugs have an apparent porosity of over 20% and lack corrosion and wear resistance. Furthermore, there was a drawback that the air permeability of individual plugs varied greatly due to variations during manufacturing. Furthermore, carbon-containing refractories such as those disclosed in JP-A-55-149750 have poor oxidation resistance and are therefore unsuitable for molten metal containers that undergo frequent use cycles. The present invention is a novel gas-blown non-carbonaceous refractory for molten metal that eliminates these drawbacks, namely the lack of corrosion resistance and abrasion resistance inherent in porous plugs, and the oxidation problems that cannot be solved with carbon-containing refractories. It provides a method for manufacturing products. That is, the present invention uses at least one type of refractory aggregate of magnesia, zirconia, zircon, alumina, and alumina-silica, and installs materials such as wires and fibers to form through holes in advance to prevent vibration. A method for producing gas-blown non-carbonaceous refractories for molten metal, which is characterized by casting into a mold, or adding a kneaded compound with a binder and water necessary for developing strength, and forming the material. be. As refractory aggregates, magnesia, zirconia, and
Naturally, zircon, alumina, and alumina-silica can be used. As a binder, in addition to sodium phosphate, sodium silicate, etc. as a dispersing agent to impart fluidity to the clay, thermosetting resins such as phenolic resins are used to impart strength in the manufacture of unfired type products. , aluminum phosphate, alumina cement, etc. Until now, the particle size or molding pressure of these materials had to be adjusted to achieve an apparent porosity of 20% or more, but they were more susceptible to erosion and had poor durability. A refractory of the present invention, which is a conventional refractory having an apparent porosity of about 20% or less and having through holes formed therein, has sufficient durability. The diameter and number of through holes can be selected appropriately, but in order to be effective, the diameter of the holes should be in the range of 0.1 mm to 3.0 mm, and if the diameter is less than 0.1 mm, the number of holes will be very large.
This is difficult to manufacture, and the bubbling force is weakened due to the viscosity of the molten steel. Moreover, if the diameter is 3 mm or more, there is a high possibility that metal or slag will enter the hole, considering the viscosity of the molten steel. The number of holes is preferably 5 or more; if it is less than 5, the amount of gas blown is insufficient and bubbling cannot be performed sufficiently. The through-holes can be manufactured by passing wire, fiber, etc. through the upper and lower molds during molding and then drawing them out after molding, or by using paraffin, resin, etc.
It is possible to form materials such as organic fibers that disappear during drying or firing by adding them to the molding process. Compared to conventional porous plugs, the bubbling effect of these through-holes can be freely changed in terms of the diameter, number, etc. of the through-holes, so if the bubbles are large, the diameter of the through-holes should be increased. Furthermore, if small bubbles are preferred, the amount of gas blown can be easily adjusted not only by the size of the bubbles but also by their number, such as by reducing the diameter of the through hole. Next, the molding method of the present invention is cast molding, and compared to the conventional uniaxial molding method, that is, the pressure molding method using a press machine, the quality is more uniform, and even products with complex shapes can be manufactured easily. In addition to the advantages of general casting molding, such as , it is easy to insert through holes in an orderly manner. Further, since no force is applied during molding, there is an advantage that the size of the hole diameter can be changed freely. The present invention will be explained below with reference to Examples. Example 1 In the case of alumina, 36 wires of 0.7 mmφ were inserted into the upper and lower plaster molds, and sintered alumina 4-1 mm 50%, 1-0.2
mm30%, 8% less than 0.043mm, and 12% ultrafine alumina less than 10μ, binder clay + 3 as a binder.
%, the above-mentioned adulterant + 0.4% and water + 4% were added to it, and after kneading, the mixture was put into a formwork placed on a diaphragm with a vibration frequency of 3100 rpm and a vibration width of 0.6 mm for 20 minutes, and then for 24 hours. After demolding, drying, and firing at 1650°C, the pore diameter was 0.7 mm, which was completely penetrating with almost no change. Example 2 Magnesia clinker 4 with MgO content of 95%
1 mm 45%, 1-0.2 mm 25%, 30% below 0.2 mm, evaporated silica + 1%, sodium pyrophosphate + 0.07% water glass + 0.02% water + 7% as a dispersing agent, and molded at 1620℃. Fired. Note that other conditions are the same as in Example 1. Example 3 Zircon material: 25 resin rods with a diameter of 1 mm were inserted and aggregates were made of 35% zircon coarse angle 4 to 1 mm, 20% 1 mm or less, 20% zircon flour, 20% zircon sand, and 5% zirconium silicate. Against alumina sol +5
%, water + 4.3%, kneaded, cast molded in the same manner as in Example 1, dried and fired at 1500°C to eliminate the resin rods. The pore diameter remained completely penetrating. Example 4 Zirconia Zirconia 2.5-1mm20%, 1-0.2mm30%, 0.2
Alumina sol + for 35% below mm, 15% below 0.043 mm
After adding 7% and water + 5% and drying the mold, it was fired at 1450°C. Other conditions are the same as in Example 1. These quality values are shown in Table 1.

[Table] Example 1 installed in a 250t ladle at Steelworks A
When argon was injected into the molten steel at 210/min (atlKg/cm ² ) and bubbling was performed 11 times out of 15 times, the wear rate was 5.5 mm/ch. 10.2 for conventional porous brick (same material)
mm/ch, demonstrating that the product of the present invention is superior. Also, since it is dense, I was worried about its resistance to sports rings, but there were no problems. The above examples show the use of the present invention in actual pots, all of which showed superior results compared to conventional porous bricks.

Claims (1)

[Claims] 1. A rod-shaped body forming a through hole of 0.1 mm to 3.0 mm is inserted into the upper and lower formwork, and magnesia, zirconia, zircon, alumina, and alumina-siliceous bones whose viscosity has been adjusted in advance are inserted into the formwork. at least one of the materials
1. A method for producing a gas-blown non-carbonaceous refractory for molten metal, which comprises casting a mixture of seeds, a binder, and water into the mold while applying vibration.