KR20000043684A - Filling material for steel-making - Google Patents

Abstract

PURPOSE: A filling material for steel-making is provided, to improve the free opening efficiency of a filling material and to recycle waste refractory bricks. CONSTITUTION: A filling material comprises 10-90 wt% of pulverized waste high silicic acid (SiO2)-based refractory brick; and 10-90 wt% of pulverized waste magnesia (MgO)-chromia (Cr2O3)-based refractory brick. Preferably the particle size of the pulverized waste refractory bricks is 0.5-10 mm.

Description

Steel Filling Material

The present invention relates to a composition for a steelmaking filler using waste refractories, and more particularly, to a steelmaking filler used for nozzle protection refractory to prevent the leakage of molten steel during ladle operation.

The ladle is a facility that takes molten steel from a converter and transfers it to a continuous casting facility. When the molten steel is moved from the ladle, the ladle is used by attaching a nozzle to adjust the flow rate or to block the flow of molten steel to control the casting speed. In general, there is a sliding nozzle (SN) method as one of the nozzles used in the ladle. The sliding nozzle is composed of an upper nozzle, two to three plates, and a lower nozzle, and has good characteristics in terms of capacity controllability of molten steel and automation and remote control, thereby improving workability. In addition, the sliding nozzle is important to the thermal shock resistance, erosion resistance, wear resistance, in particular, since the plate portion is used in the assembly of the mechanical device, mechanical strength and dimensional accuracy is important.

Steel sliding fillers are used to protect these sliding nozzles from molten steel and to prevent molten steel outflow during ladle operation. Steelmaking fillers should be excellent in thermal shock resistance, have low abrasion and deformation during hot use, and be strong against reaction or erosion with molten steel or slag. Silica (SiO ₂ ) quality refractory bricks or chromia (Cr ₂ O ₃ ) quality refractory bricks are used as fillers for steelmaking that satisfy these conditions.

However, siliceous refractories have a very high coefficient of thermal expansion below 600 ° C., and chromium refractories have a bursting phenomenon in which spinel minerals in the chromite ore absorb and expand iron oxide from the outside at high temperatures. Expansion and the like occur due to sintering, thereby lowering the natural free opening rate. In addition, the production cost is increased by using the raw material when manufacturing the steelmaking filler has a weak economical disadvantages.

The present invention has been made to solve such a problem, the purpose is to recycle the resources using waste fire-resistant bricks, to solve the problem of pollution and at the same time to bring down the cost of the product and low expansion rate natural porosity This high steel filling material is provided.

In order to achieve the above object, the present invention provides a weight ratio of the waste solid siliceous refractory brick and waste magnesia-chromia (MgO-Cr ₂ O ₃ ) quality refractory brick pulverized to fine powder 10:90 ~ 90:10 It is characterized by.

The particle size of the waste silicic acid refractory bricks and waste magnesia-chromiac refractory brick pulverization is preferably 0.5 to 10 mm.

Hereinafter, the present invention will be described in more detail.

In general, the high silica (SiO ₂ ) quality refractory brick is one or a combination of high-purity natural silica or feldspar, etc., and the content of SiO ₂ component is usually 60% by weight or more. These high silice refractory bricks are used in semi-permanent and permanent fields such as torpedo ladle cars, converters, electric furnaces, ladles, vacuum degassing plants and tundish. Generates high waste siliceous refractory bricks.

Since the waste silicic acid refractory brick is typically used in a semi-permanent or permanent field of the furnace, there is little slag or metal on the surface of the refractory brick because it is not directly in contact with molten steel or slag. There is no need, and in the present invention, it is not particularly limited as a waste silicic acid refractory brick.

In addition, magnesia-chromia refractory brick usually contains about 10 to 20% by weight of chromia, and there are direct bonds, semi-rebonds, and rebonds. . Direct bonded refractory bricks are prepared by adding suitable binders to the blend using high purity synthetic magnesia clinker and natural chromite as sources of magnesia and chromia, respectively, and baking them at high temperatures of 1700 ° C. or higher. On the other hand, recombination refractory bricks are manufactured by molding and firing magnesia clinker and chromite ore in the same manner as direct-bond refractory bricks by using an electrolytic mag-clinker having a small amount of impurities previously dissolved, cooled, and ground in an electric furnace. In addition, there is an intermediate property of direct bonding and recombination, which is called quasi-recombination refractory brick, which is used by mixing a mixture of magnesia clinker, chromite, and electrolytic mag-cro.

This magnesia-chromiatrile refractory brick is used as a built-in refractory material in a vacuum degassing facility, and when it is recovered after use, the slag or metal penetrating layer is generally about 5 mm near the movable surface of the refractory brick. It is preferable to use after removing a permeation layer for reproducible expression, and in this invention, it is not specifically limited as a waste magnesia-chromiayl refractory brick.

The particle size of the waste silicic acid and waste magnesia-chromiac refractory brick grind used in the present invention should be 0.5 to 10 mm. When the particle size of the waste refractory brick pulverized becomes less than 0.5mm, the rapid sintering occurs when used as a filler, the natural porosity is lowered. In addition, when the particle size of the waste refractory brick pulverized becomes more than 10mm, the filling rate is lowered when used as a filler and the molten steel penetrates and solidifies, thereby decreasing the natural porosity.

In addition, in the present invention, the weight ratio of the above-mentioned waste silicic acid and waste magnesia-chromiac refractory brick pulverization should be 10:90 to 90:10. This is because when the pulverized material of each waste refractory brick constituting the filler becomes 10 wt% or less, molten steel penetrates and solidifies due to a decrease in self-sintering property, thereby decreasing the natural porosity.

Hereinafter, a preferred embodiment of the present invention will be described with reference to experimental data.

Example

The waste magnesia-chromia refractory brick recovered from the ladle and the waste magnesia-chromia refractory brick recovered from the vacuum degassing plant were crushed to various particle sizes, and then The mixture was mixed in various weight ratios and used 100 times as a ladle filler.

Table 1 is presented to compare the properties of the various steel fillers. First, Specimens 1 and 2 have a particle size of 0.5 to 10 mm of the waste silicic acid and waste magnesia-chromia refractory brick pulverized according to the present invention, the ratio of the composition of the waste silicic acid and waste magnesia-chromia refractory brick crushed 10:90 and 90:10, respectively. In Comparative Examples 3 and 4, the particle sizes of the waste silicic acid and waste magnesia-chromiac refractory brick ground were 0.5 mm or less and 10 to 15 mm, respectively. In Comparative Examples 5 and 6, the composition ratios of the waste silicic acid and waste magnesia-chromiac refractory brick pulverized were 5:95 and 95: 5, respectively.

Experiment No. Grain Size (mm) Weight Ratio of Waste High Silica Refractory Bricks and Waste Magnesia-Chromics Refractory Brick Grinding Natural Opening Rate (%) Remarks One 0.5 to 10 10:90 100 - 2 0.5 to 10 90:10 100 - 3 ^* To 0.5 10:90 89 Sintering 4 ^* 10 to 15 70:30 85 Molten steel penetration 5 ^* 0.5 to 10 5:95 87 Molten steel penetration 6 ^* 0.5 to 10 95: 5 86 Molten steel penetration

Comparative Example

As disclosed in Table 1, specimens 1 and 2 prepared in accordance with the present invention were all excellent in natural porosity of 100%. However, in Comparative Example 3, the rapid sintering of the filler occurred and the natural porosity was lowered to 89%. In Comparative Example 4, the natural porosity was reduced to 85% due to the decrease in the filling rate and the penetration of the molten steel. In addition, both Comparative Examples 5 and 6 showed that the molten steel penetrates and solidifies due to a decrease in self-sintering property, so that the natural porosity decreases to 87 and 86%, respectively.

As described above, the present invention provides a steelmaking filler having an excellent feature of recycling waste refractories in terms of preventing environmental pollution as well as improving the natural porosity of the filler by manufacturing the steelmaking filler using waste firebrick.

Claims (2)

In the steelmaking filler refractory composition, A filling material for steelmaking, characterized in that the weight ratio of the waste high siliceous refractory brick pulverized to fine powder and the waste magnesia-chromiatic refractory brick pulverized is 10:90 to 90:10. The steelmaking filler according to claim 1, wherein a particle size of the waste silicic acid refractory brick and the waste magnesia-chromiac refractory brick pulverized powder is 0.5 to 10 mm.