KR100328934B1 - Method for manufacturing aluminum oxide-calcium oxide group flux using waste brick - Google Patents

Abstract

PURPOSE: A method for manufacturing Al2O3-CaO based flux with superior adsorption against oxides of hot metal by using waste refractory bricks is provided. CONSTITUTION: The method includes the steps of crushing Al2O3 based waste refractory bricks, wherein particle size of crushed refractory bricks is less than 0.5 mm; mixing the crushed refractory bricks and quick lime in a ratio of 1:1; adding 1 to 10 % of binder to the mixture of the crushed refractory bricks and quick lime; heating above mixture at 900 to 1200 deg.C; and forming the mixture into a flux lump with a size of 30-40mmx30-40mm.

Description

Method for manufacturing aluminum oxide-calcium oxide group flux using waste brick}

The present invention relates to a method for producing an aluminum oxide (Al ₂ O ₃ ) -calcium oxide (CaO) -based solvent using waste smoke, more specifically, using an amorphous waste smoke of aluminum oxide (Al ₂ O ₃ ) -based The present invention relates to a method for producing an aluminum oxide-calcium oxide solvent having excellent adsorption and removal capability of an oxide in molten iron and free of impurities such as titanium (Ti).

In the steelmaking process, molten iron from the blast furnace is manufactured from various types of steel required by the consumer. The molten iron produced in the blast furnace contains various impurities, and if these impurities remain in the steel, the quality of the steel is poor. Therefore, it is necessary to go through the refining process to remove impurities of the molten steel.

The refining process of molten iron in steel mills is divided into converter process and secondary refining process.

In the converter process, oxygen is injected into the molten iron drawn from the blast furnace to oxidize impurities present in the molten iron to remove them in the form of oxides. In this process, a large amount of dissolved oxygen dissolved in molten steel is removed by adding a deoxidizer such as aluminum (Al) or silicon (Si), and deoxidizer such as aluminum and silicon is combined with dissolved oxygen dissolved in the molten iron to form an oxide. Change.

The following reaction formula shows the deoxidation reaction of aluminum and silicon to remove dissolved oxygen in the molten iron, and by this chemical reaction, dissolved oxygen in the molten steel is released from the molten iron in the form of aluminum, silicon and the like.

As described above, an oxide (Al ₂ O ₃ , SiO ₂ , MnO, etc.) generated by the addition of a deoxidizer and an oxide (MgO, Al ₂ O _3, etc.) mixed from a refractory are produced in a molten steel. In this case, oxides remain in the steel and the quality of the steel is degraded. Therefore, these oxides should be removed in the secondary refining process.

In the secondary refining process, which removes the oxides in the molten steel, the molten steel is stirred to float the oxides, and then a solvent that adsorbs the oxides is introduced to adsorb the floating oxides to the solvent to remove the oxides generated in the converter process. .

The oxide is removed by the secondary refining process to improve the cleanliness and quality of the molten steel.

In order to obtain high clean steel, slag covering the surface of molten steel should be manufactured with low melting temperature and excellent absorption ability of deoxidation products.

Slag refers to a compound of molten iron produced during molten metal refining, mainly an aluminum oxide-calcium oxide-silicon dioxide (Al ₂ O ₃ -CaO-SiO ₂ ) -based compound, and top slag is the ability to absorb oxides in slag. The composition of this excellent slag area | region is said.

1 shows the composition of a top slag region in an Al ₂ O ₃ -CaO-SiO ₂ system (ternary system), and the table below shows the composition of the top slag region.

ingredient CaO Al ₂ O ₃ SiO ₂ Composition (% by weight) 57-60 28-32 ≤10

In order to obtain the top slag of the desired composition, the oxides present in the molten steel must be removed. Such oxides are mainly removed using a solvent which is a compound of aluminum oxide-calcium oxide (Al ₂ O ₃ -CaO).

The following formula is a reaction formula showing a process of removing an oxide present in the molten iron using an aluminum oxide-calcium oxide compound (mAl ₂ O ₃ · nCaO).

Conventional aluminum oxide-calcium oxide-based solvents used to remove oxides present in molten steel are prepared by adding calcium oxide to aluminum oxide-based natural ores.

Since a small amount of titanium (Ti) is contained in the aluminum oxide ore used as a raw material of the solvent, about 2 to 3% of titanium remains in the solvent prepared using the aluminum oxide ore.

Titanium is an element that rapidly reduces the fatigue life of steel when it remains in steel. Therefore, when steel is manufactured using molten steel remaining by dissolving titanium contained in the solvent, the quality of steel is deteriorated. In particular, the quality of steel in the case of bearing steel and spring steel, which are used for rotating machinery, automobile main parts, which require high fatigue resistance There is a problem that has a fatal adverse effect on.

The present invention for solving the above problems is to provide a method for preventing the deterioration of the steel by titanium by producing a solvent having excellent absorption and removal ability of the oxide in the molten steel without using titanium in the amorphous waste lead. do.

1 is a graph showing slag composition and region in a ternary system (Al ₂ O ₃ , SiO ₂ , CaO).

In order to achieve the above object, the present invention provides a high aluminum oxide-based amorphous waste smoke generated as waste in a vessel containing molten iron in a steelmaking plant (hereinafter referred to as 'ladle') to a size of 0.5 mm or less. Crushing process; Adding and mixing quicklime of 0.5 mm or less in a ratio of 1: 1 to the crushed waste smoke; Adding 1-10%% of a binder to the mixture of the spent smoke and quicklime and mixing the mixture; Heating the mixture of the waste smoke and the quicklime and the binder at a temperature of 900 to 1200 ° C; And a method for producing an aluminum oxide-calcium oxide-based solvent using an amorphous waste lead made of a process for preparing the heated mixture with a molten steel refining solvent having a size of 30-40 mm × 30-40 mm.

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

In the present invention, as a raw material for producing a molten steel refining solvent, a high aluminum oxide-based amorphous waste smoke generated as waste in the ladle is used.

As can be seen from the following table showing the composition of the amorphous waste smoke, the amorphous waste smoke contains a large amount of high-purity aluminum oxide (Al ₂ O ₃ ) and some magnesium oxide (MgO), while titanium oxide (TiO ₂ ) Not included.

ingredient Al ₂ O ₃ MgO content More than 86% 7% or more

By using waste lead which was used as waste as raw material for solvent production, high purity aluminum oxide can be obtained with low processing cost without material cost, and titanium oxide (TiO ₂ ) is not included in waste smoke, and titanium is mixed in molten iron. Is also solved.

In addition, the magnesium oxide component contained in a small amount during the waste smoke plays a role in suppressing the erosion of the refractory.

The waste lead is broken at the breaking particle size of 0.5mm or less, and the breaking particle size of 0.5mm or less improves the reactivity with calcium oxide (CaO) or silicon dioxide (SiO ₂ ) in molten iron or in slag. It is for easily forming slag.

The pulverized waste lead with the size of 0.5mm or less quicklime is added and mixed in a 1: 1 ratio, and the gypsum binder is added to the mixture of the waste lead and the quicklime in an amount of 1-10% and mixed.

The mixture of the above waste smoke, quicklime and gypsum binder is heated to a temperature of 900 to 1200 ° C. and then prepared into a solvent having a size of 30-40 mm × 30-40 mm.

The gypsum binder is used to maintain the bonding strength. When used in an amount of more than 10%, the component of the binder acts as an impurity to impair the cleanliness of molten steel while the bond strength is used in an amount less than 1%. Since it is not suitable, it is preferably added in an amount of 1 to 10%.

On the other hand, when the mixture of the waste smoke and the quicklime and the caking agent is heated at a temperature of less than 900 ℃ the gypsum caking agent in the mixture decreases the mass ratio and strength of the mixture while heating at a temperature of more than 1200 ℃ Although proper strength is maintained, considering the heating temperature of a general metal oxide solvent manufacturing process, excessive manufacturing cost increases, so heating at a temperature of 900 to 1200 ° C is preferable.

The production of the heated mixture with the size of 30-40mm × 30-40mm is required because a certain level of granularity is required because it passes several times from the manufacture to the molten steel. This is because the reactivity with the oxide is lowered or the efficiency of removing the oxide is lowered.

The present invention will be described in detail through the following examples.

The slag was prepared by adding the solvent of the present invention to molten steel for producing bearing steel in the field, and analyzed the produced slag and the results are shown in Table 1 below.

ingredient CaO Al ₂ O ₃ SiO ₂ Basicity (CaO / SiO ₂ ) Top slag area (target value) 57-60% 28-35% below 10 5.5 or more When using conventional solvent 61.6% 27.4% 11% 5.6 When using the solvent of the present invention 58.0% 32% 10% 5.8

As can be seen from the results of Table 1, the slag prepared using the solvent of the present invention was excellent in the composition of the top slag area, the basicity of the top slag area was particularly excellent as compared with the conventional material.

Table 2 below shows the titanium content in the molten iron and the total oxygen content in the wire rod product after the refining operation of the molten steel using the solvent of the present invention. The total oxygen content refers to the total amount of oxygen in the oxide remaining in the steel.

division When using conventional solvent When using the solvent of the present invention Titanium (Ti) content in molten iron (wt%) 0.004-0.005% Less than 0.0015% Total oxygen content in 12ø wire products (total [O]) 11 ppm 8-10ppm

As can be seen from the results of Table 2, the content of titanium, which causes a decrease in fatigue life, was reduced by about 0.003% when the solvent of the present invention was used as compared with the conventional solvent.

In addition, the total amount of oxygen in the wire rod product was also reduced by about 1 to 3 ppm when using the solvent of the present invention compared with the case of using a conventional solvent.

According to the present invention having the above structure, titanium is not mixed in molten steel by manufacturing a molten steel refining solvent using a high-aluminum oxide-based amorphous waste lead that does not contain titanium, and thus requires high fatigue properties such as bearing steel and spring steel. It can improve the quality of high-grade steel, and obtain high-purity aluminum oxide raw material with low processing cost without material cost from waste smoke and landfill as waste, which not only contributes to cost reduction but also can actively respond to environmental problems.

In addition, the magnesium oxide component added in small amounts in the waste smoke also has the effect of suppressing the erosion of the refractory.

Claims (1)

In preparing a solvent for removing the oxide in the molten steel, the process of crushing the amorphous waste smoke to less than 0.5mm in size; Adding and mixing quicklime of 0.5 mm or less in a ratio of 1: 1 to the crushed waste smoke; Adding 1 to 10% of a gypsum binder to the mixture of the waste smoke and quicklime and mixing the mixture; Heating the mixture of the waste smoke, quicklime and gypsum binder at a temperature of 900 to 1200 ° C; And manufacturing the heated mixture with a molten steel refining solvent having a size of 30-40 mm × 30-40 mm.

Images