KR100741491B1 - Deoxidizing refractory composition for preparing steel with high purity and preparing method thereof - Google Patents

Abstract

The present invention relates to a deoxidation refractory composition for producing high clean steel and a method of manufacturing the same, and more particularly, the deoxidation refractory composition includes an Al-containing material, a Ca-containing material, a silica flower, a pearlite, and a Li-containing flux. The layer comprises CaO.

The deoxidation refractory composition according to the present invention reacts rapidly with molten steel and slag to effectively remove oxygen and impurities present in molten steel and slag produced by the oxygen blowing converter steelmaking method without generating dust or white smoke. In addition, by using the deoxidation refractory composition can be produced high clean steel.

Deoxidation refractory composition, manufacturing method, core material, surface treatment, aluminum, CaO.

Description

DEOXIDIZING REFRACTORY COMPOSITION FOR PREPARING STEEL WITH HIGH PURITY AND PREPARING METHOD THEREOF}

[Technical Field]

The present invention relates to a deoxidation refractory composition for manufacturing high-clean steel and a method of manufacturing the same, and more particularly, oxygen present in molten steel and slag produced by the steelmaking method without oxygen or flue gas by rapidly reacting with molten steel and slag. And it relates to a deoxidation refractory composition for producing a high clean steel that can effectively remove impurities present in the steel and a method of manufacturing the same.

[Private Technology]

Typically, the molten iron produced in the blast furnace contains about 6 to 8% of impurity components such as C, Si, Mn, P, and S. In order to remove such impurity components, a refining steelmaking method using pure oxygen blowing to remove impurities by blowing pure oxygen is used. When pure oxygen is supplied during the smelting steelmaking process by pure oxygen smelting, impurities in the molten iron react with oxygen to rise as an upper slag layer in the form of oxides such as CO, SiO ₂ , MnO, P ₂ O _5, and the like. . Therefore, impurities can be removed by separating the floating oxide.

However, during the refining operation by the pure oxygen blowing refining steelmaking method, the oxygen of high partial pressure remains in the slag layer and the molten steel due to the excess oxygen supply, and the remaining oxygen is in combination with the metal components introduced to make the desired steel. To form impurities that cause fatal defects in the product. Therefore, in the refining process for obtaining clean steel, a process for removing excess oxygen is essential.

Accordingly, the molten steel produced in the converter or the electric furnace is transferred to the ladle and undergoes a secondary refining process.In this case, oxygen and oxygen present in the molten steel or slag are added by adding a deoxidizer or an alloying material for high purification of the molten steel and adjustment of desired steel composition. Remove impurities remaining in the river.

As such a method for high purification of molten steel, Korean Patent No. 1997-0004987 discloses 30 to 60% by weight of aluminum metal, 20 to 50% by weight of CaCO ₃ , 10% by weight of Al ₂ O _3, 10% by weight of SiO ₂ , It is disclosed to use slag aids including Na + K, N, Cl + F and the like as other additives. In addition, Korean Patent No. 264994 discloses a magnesium-based ladle slag preparation for high clean steel, which includes metal magnesium, dolomite and sodium silicate, and has an average particle diameter of 20 to 40 mm, and Korean Patent No. 361932 discloses aluminum (Al chip). Or Al dross), quicklime, iron, aluminum oxide, silicon oxide, and wheat flour are disclosed.

Korean Patent No. 387933 discloses a method for producing a dissolving agent, that is, a deoxidizer using Al waste dross, which is generated during the production of aluminum, and Korean Patent No. 446469 as a metal by-product generated during the production and use of metal materials. A deoxidizer for producing alloy steel produced using a solvent selected from a metal selected from Al, Mg, Si and Ca, calcium silicate or calcium aluminate, and binders such as water glass, starch and resin is disclosed.

All of the above methods use a material containing aluminum metal with good oxidation power, and in particular, ash, aka dross, generated by dissolution of aluminum, which is a nonferrous metal. However, the black dross and the salt cake of the dross have a problem of generating a bad smell and white smoke during use because a large amount of aluminum nitride compound (AlN) is contained by reacting with nitrogen in the air during the formation of the dross.

In addition, CaO-based raw materials such as limestone and slaked lime are used to remove impurities such as oxide inclusions, sulfur and phosphorus in molten steel. In the case of sulfur, it is removed in the form of CaS sulfide by the added CaO. However, since CaO has a high melting point, it is difficult to melt in the slag layer, and the endothermic reaction when reacting with slag lowers the temperature of the slag layer which is in contact with the atmosphere, so that the reaction may not occur completely. Accordingly, there is a problem in that the oxidizing power and inclusion absorption efficiency is lowered.

In addition, in order to remove impurities such as oxide inclusions, sulfur and phosphorus in molten steel, calcium silicate and calcium aluminate generated during cement production are used as raw materials, in which case a large amount of calcium silicate or potassium aluminate contained in There is a problem that the clean steel is difficult to manufacture due to the sulfur component.

The present invention is to solve the above problems, an object of the present invention is to react quickly with molten steel and slag, impurities present in the molten steel and slag produced by the molten steel and slag produced by the oxygen blowing converter steelmaking without the generation of dust or white smoke It is to provide a deoxidation refractory composition for producing a high clean steel that can effectively remove the and a method for producing the same.

In order to achieve the above object, the present invention provides a deoxidation refractory composition for producing a high clean steel comprising a core material, and a surface treatment layer surrounding the core material. The core material may include an Al-containing material, a Ca-containing material, a silica flower, a pearlite, and a Li-containing flux, and the surface treatment layer may include CaO.

The present invention also provides a core material using a composition for forming a core material comprising an Al-containing material, a Ca-containing material, a silica flower, a pearlite, and a Li-containing flux, wherein the core material is prepared by CaO, a dispersion medium, a binder, a peptizing agent. It provides a method for producing a deoxidation refractory composition for manufacturing high-clean steel comprising the step of surface-treating the composition for forming a surface treatment layer comprising a, and an antifoaming agent.

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

The present invention relates to a deoxidation refractory composition for producing high clean steel, and a method for manufacturing the same. In the present invention, a core material including Al-containing material, Ca-containing material, silica flower, pearlite, and Li-containing flux and surrounding Ca include CaO. By using a deoxidation refractory composition having a surface treatment layer, the slag formed in the steelmaking refining operation by pure oxygen blowing and the deoxidation of excess oxygen in molten steel and impurities remaining in the molten steel, that is, oxide inclusions, sulfur, phosphorus, etc. Can be removed. In addition, it can be used to produce high clean steel without the generation of dust and white smoke.

That is, the deoxidation refractory composition for manufacturing high-purity steel according to an embodiment of the present invention includes a core material and a surface treatment layer surrounding the core material. In this case, the core material includes an Al-containing material, a Ca-containing material, a silica flower, a pearlite, and a Li-containing flux, and the surface treatment layer includes CaO.

More preferably, the core material is 20 to 50% by weight of Al-containing material, 5 to 40% by weight of Ca-containing material, 3 to 5% by weight of silica flower, 5 to 10% by weight of pearl rock and Li-containing flux based on the total weight of the core material. 5 to 10 weight percent.

Hereinafter, the method for preparing the deoxidation refractory composition will be described. The deoxidation refractory composition having the structure described above may be formed using a composition for forming a core material including an Al-containing material, a Ca-containing material, a silica flower, a pearlite, and a Li-containing flux. After the core material is prepared, the core material is prepared by a manufacturing method comprising the step of forming a surface treatment layer by surface treating the composition for forming a surface treatment layer including a CaO, a dispersion medium, a binder, a peptizing agent, and an antifoaming agent. Can be.

In more detail below, first, an Al-containing material, Ca-containing material, silica flower, pearlite, and Li-containing flux are mixed to prepare a composition for forming a core material. More preferably, 20 to 50% by weight of Al-containing material, 5 to 40% by weight of Ca-containing material, 3 to 5% by weight of silica flower, 5 to 10% by weight of pearl rock and 5 to 10% of Li-containing flux, based on the total weight of the deoxidation refractory composition. It is preferable to include the weight percent. The content range shows an excellent deoxidation effect by optimizing the content ratio between components.

The Al-containing material is for supplying Al in the refractory composition. The Al reacts with oxygen in the molten steel to remove oxygen in the molten steel in the form of an oxide.

As the Al-containing material, metal aluminum powder, aluminum chips, aluminum dross and mixtures thereof may be used.

In the case of the aluminum powder, there is a risk of explosion due to a sudden reaction when used in an excessive amount, it is preferable to use a mixture of aluminum chips and aluminum dross, specifically 5 to 10% by weight of metal aluminum It is preferable to use a mixture of 15 to 25% by weight of Al chips and 15 to 30% by weight of Al dross.

In addition, the finer the aluminum powder is, the higher the surface activity becomes, which easily reacts with oxygen in the atmosphere to form an oxide film on the surface of the metal particles. Accordingly, in order to prevent the reaction of the metal particles and oxygen from slowing down as the oxide film is formed, a coating of oil such as light oil, kerosene, vegetable oil, or lubricating oil may be used on the surface of the metal aluminum powder.

As the aluminum dross, a white dross, a black dross, and a salt cake may be used. White dross is generated by contact with air when the pure aluminum is dissolved, and contains about 70% of aluminum, most of which is alumina. Black Dross is treated with flux to prevent surface oxidation during the dissolution of aluminum. It contains 25 to 40% of aluminum and contains a relatively large amount of fluorine in addition to the remaining alumina. In addition, the salt cake is left after mixing and melting the dross with various salts, which contains less than 25% of aluminum and contains a significant amount of salts. Among the aluminum dross, it is more preferable to use a white dross which is high in purity and can prevent white smoke and odor generation.

The calcium (Ca) -containing material is for providing CaO, which serves to remove oxides and sulfur in the molten steel together with the Al in the refractory composition.

As the Ca-containing material, one or more selected from the group consisting of CaO, Ca (OH) ₂ , CaCO _3, and mixtures thereof may be used. They have high purity and high reactivity, and can easily supply CaO.

The pearlite contains moisture in the crystal structure, and this moisture rapidly evaporates at a high temperature to cause a foaming action. Accordingly, even if the deoxidation refractory composition is not added to the front of the slag layer, the deoxidation refractory composition may rapidly spread to the front of the slag layer by the foaming action of pearlite.

The silica flower increases the bonding strength between the constituent materials of the composition for forming the core material, thereby preventing the deoxidation refractory composition from collapsing during use.

Since CaO included in the deoxidation refractory composition has a high melting point, the reaction rate may be lowered and the reaction may not occur completely. In contrast, by using lithium-containing flux, the melting temperature of CaO can be lowered to increase the reaction rate. The lithium-containing flux may be one or more selected from the group consisting of spodumene, petalite, repidolite, and the like.

The composition for forming the core material may further include a binder to facilitate the molding process of the deoxidation refractory composition.

Examples of the binder include an inorganic binder including sodium silicate and calysilicate; And organic binders including wheat flour, molasses, starch, resin, and the like. More preferably, in order to prevent a phenomenon in which the sodium silicate is broken into a whitening phenomenon by reaction with moisture in the air at room temperature, it is preferable to use a mixture of sodium silicate and silicate in a weight ratio of 2: 1 to 2: 1.5. desirable. Such a binder is preferably included in 5 to 10% by weight based on the total weight of the core material.

A core material is manufactured through a molding process from the composition for forming a core material having the above configuration.

The molding process may be carried out using a conventional molding method, it is preferable to carry out the molding process of briquette or pelletizing.

The core material produced through the molding process as described above has a form of briquettes or pellets, and preferably has an average particle diameter of 10 to 30mm. If the average particle diameter of the core material is less than 10 mm, the particles are too small and may be scattered when added to molten steel or slag. If the average particle diameter is more than 30 mm, the particles are too large and difficult to add.

Thereafter, the prepared core material is coated with a composition for forming a surface treatment layer including CaO, a dispersion medium, a binder, a peptizing agent, and an antifoaming agent and dried to form a surface treatment layer.

The composition for forming the surface treatment layer is composed of CaO slip, and basically includes CaO and a dispersion medium, and further includes a peptizing agent, a binder, and an antifoaming agent to enhance the surface treatment effect.

The CaO is the same as described above. However, the smaller the particle size of the CaO included in the surface treatment layer, the smoother the surface treatment to the surface of the core material is preferable. In the present invention, it is preferable to have an average particle diameter of 0.45 μm or less.

Water may be used as the dispersion medium.

Preferably, the CaO and the dispersion medium are preferably mixed in a weight ratio of CaO 15:85 to 35:65, and preferably in a weight ratio of 20:80 to 30:70. Within the content ratio range, the CaO fine powder has good slip stability, so that the workability during agitation or spraying is good, and the coating material having an appropriate thickness on the surface of the core material is good. If it is out of the content range of the small amount of CaO powder, the coating layer is thinner, the bonding strength is reduced, the excess CaO powder to form a thick and coarse coating layer becomes unstable in actual use.

The peptizing agent serves to prevent sedimentation and aggregation in a state where CaO fine powder is dispersed in water by CaO slip, and typically, tripolyphosphate, sodium hexametaphosphate, and the like may be used. The peptizing agent may be included in 0.1 to 1.5% by weight based on the total weight of the composition for forming the surface treatment layer, more preferably 0.1 to 0.5% by weight. If the content of the peptizing agent is less than 0.1% by weight or more than 1.5% by weight, the particles of fine CaO powder are not agglomerated to obtain a stable suspended slip, which is not preferable because the sedimentation phenomenon occurs due to sedimentation over time. .

The binder serves to enhance the stability and bonding strength of the slip, and typically may be polyvinyl alcohol (PVA), polyvinylacetate (PVAS) or the like. It is preferable to use the binder completely melted in the dispersion medium using hot water, in which case the binder is preferably contained in 2 to 4% by weight in the dispersion medium. If the content of the binder is less than 2% by weight, it is difficult to obtain the bonding force, so that the coating layer is easily broken, and if it exceeds 4% by weight, it is not preferable because it is difficult to completely melt and difficult to achieve stable slip.

The antifoaming agent serves to remove bubbles generated during the stirring of the composition for forming the surface treatment layer, and typically, sodium naphthalene sulfite may be used. The antifoaming agent may be included in 0.1 to 1.5% by weight based on the total weight of the composition for forming the surface treatment layer, more preferably 0.1 to 0.5% by weight.

The composition for forming a surface treatment layer having the above-described composition is surface-treated on the core material by using a surface treatment method such as spraying at the time when the molding of the core material to a predetermined size is completed in a molding process such as pelletizing.

As such, when the core material is molded to a desired size, CaO slip is sprayed to form a coating on the surface of the core material, thereby forming a surface adhesion layer having a firm and constant thickness. At this time, the surface treatment can be carried out using a conventional coating method, more preferably using a spraying method.

After the molding and surface treatment of the core material, the deoxidation refractory composition including the core material on which the surface treatment layer is formed by dehydration and drying may be added to a drying furnace.

The surface treatment layer surrounds the core material and suppresses chipping of the core material and consequent dust generation. In addition, CaO included in the surface treatment layer serves to prevent slag forming or unreacted CaO generation by inducing sequential melting reactions. In this case, the finally generated surface treatment layer may have a thickness of 1 mm or less, and more preferably, may have a thickness of 0.05 to 1 mm.

The deoxidation refractory composition prepared by the above method can quickly remove oxygen and impurities present in molten steel and slag produced by the oxygen blowdown steelmaking method without rapidly generating dust or white smoke by reacting with molten steel and slag. have. In addition, high clean steel can be produced by using the deoxidation refractory composition.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

Example  1 to 12. Deoxidation  Preparation of Refractory Composition

To prepare a composition for forming a core material by mixing according to the configuration and content described in Table 1.

The pellet-shaped core material was molded using the prepared core material composition. In the case of pelletizing molding, the core materials on the rotating disk are spherical to form a spherical shape, and the molding is performed such that the average particle diameter is 10 to 30 mm or more by 95% or more by the pelletizing. It was.

At the time of completion of molding, the composition for forming a surface treatment layer containing CaO was spray coated. The composition for forming the surface treatment layer was mixed with 30% by weight of ultrafine CaO of 0.45 μm, 0.5% by weight of sodium tripolyphosphate, 0.5% by weight of sodium naphthalene sulfite, and 69% of 2% aqueous solution of PVA after mixing with a strong stirrer to prevent agglomerated particles. CaO slip was prepared by stirring.

Example (Unit: wt%) One 2 3 4 5 6 7 8 9 10 11 12 Al powder 5 5 5 5 5 5 10 10 10 10 10 10 Al chip 15 15 15 20 20 20 20 20 20 25 25 25 Al dross 30 30 30 25 25 25 20 20 20 15 15 15 CaO 20 - - 20 - - 20 - - 20 - - CaCO ₃ - 20 - - 20 - - 20 - - 20 - Ca (OH) ₂ - - 20 - - 20 - - 20 - - 20 Silica flower 8 8 8 8 8 8 8 8 8 8 8 8 Mother-of-pearl 4 4 4 4 4 4 4 4 4 4 4 4 Sodium Silicate 6 6 6 6 6 6 6 6 6 6 6 6 Silicate 3 3 3 3 3 3 3 3 3 3 3 3 Spodumene 5 5 5 5 5 5 5 5 5 5 5 5 Wheat flour 4 4 4 4 4 4 4 4 4 4 4 4

Table 2 shows the components in percentage in the core material prepared according to the formulation of the above examples.

Example (Unit: wt%) One 2 3 4 5 6 7 8 9 10 11 12 Al metal 46.2 50.4 49.1 46.4 50.6 49.3 47.2 51.4 50.0 48.5 52.7 51.3 CaO 23.1 16.1 18.4 23.0 16.1 18.3 22.7 15.8 18.1 22.1 15.4 17.6 SiO ₂ 16.8 18.3 17.8 16.7 18.2 17.7 16.5 17.9 17.5 16.1 17.4 17.0 Al ₂ O ₃ 8.32 9.08 8.83 8.29 9.05 8.8 8.18 8.91 8.67 7.97 8.66 8.44 Li 0.52 0.57 0.55 0.52 0.57 0.55 0.51 0.56 0.54 0.50 0.54 0.53 Etc 5.06 5.55 5.32 5.09 5.48 5.35 4.91 5.43 5.19 4.83 5.3 5.13

Comparative example  One. Deoxidation  Preparation of Refractory Composition

A deoxidation refractory composition was prepared comprising 40 wt% metallic aluminum, 40 wt% CaO, 10 wt% Al ₂ O ₃ , 8 wt% SiO ₂ , and 2 wt% other components.

Comparative example  2. Deoxidation  Preparation of Refractory Composition

A deoxidation refractory composition was prepared comprising 50 wt% metallic aluminum, 30 wt% CaO, 9 wt% Al ₂ O _3, 9 wt% SiO ₂ , and 2 wt% other components.

Molding strength, white smoke, dust generation and melting temperature of the deoxidized refractory composition prepared in Example were measured. The results are shown in Table 3 below.

In Table 3 below, ◎ = excellent, ○ = good, Δ = normal, and × = defect.

Example One 2 3 4 5 6 7 8 9 10 11 12 Molding strength before coating △ △ △ ○ ○ ○ ○ ○ ○ × × × Forming Strength after Coating ○ ○ ○ ◎ ◎ ◎ ◎ ◎ ◎ △ △ △ White smoke △ △ △ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ Melting temperature (℃) 1547 1545 1561 1463 1471 1489 1453 1467 1492 1416 1425 1445

As a result of the experiment, the deoxidation refractory composition of Examples 4 to 8 of Examples 1 to 12 had excellent molding strength, there was no white smoke, and the melting temperature was 1450 to 1470 ° C.

From these results, it was found that the molding strength and the generation of white lead of the deoxidized refractory composition were closely related to the Al dross content. In addition, it was confirmed that the coating strength of the deoxidation refractory composition increased by coating by CaO slip.

The deoxidation refractory compositions of Examples 4 to 8 and Comparative Examples 1 and 2 were respectively injected into the slag layer of molten steel received on the ladle for secondary refining to evaluate the deoxidation efficiency, the absorbency of impurities, the reactivity, and the inclusion absorption ability.

Typically 100 tons of ladle, 400 to 500 kg of slag is formed per 100 tons of molten steel, the content of oxidized MnO is 5 to 8%. Therefore, the deoxidation refractory composition of the present invention according to the amount of slag was at least 40kg / cycle and the deoxidation efficiency of slag was evaluated by changing the MnO composition in the slag before and after the addition.

Incidentally, the inclusion absorbency was measured by hot annealing pickling (HAP) of the cast and rolled carbon steels, evaluating the surface quality of the carbon steels, and comparing the average number of inclusions per hot rolled coil. The measurement results are shown in Table 4 below.

MnO Composition (%) Deoxidation Efficiency (%) Responsive The number of inclusions Before adding deoxidation refractory composition After adding deoxidation refractory composition Example 4 6.9 2.1 69.6 ◎ 0.07 Example 5 6.4 1.9 70.3 ◎ 0.06 Example 7 7.3 2.6 64.4 ○ 0.09 Example 8 7.5 2.9 61.3 ○ 0.11 Comparative Example 1 6.8 3.6 47.1 × 0.16 Comparative Example 2 7.5 3.7 50.7 △ 0.15

As shown in Table 4, the deoxidation refractory compositions of Examples 4 and 5 showed the best slag deoxidation efficiency, reactivity and inclusion absorption capacity.

The deoxidation refractory composition according to the present invention can rapidly react with molten steel and slag to effectively remove oxygen and impurities present in molten steel and slag produced by the oxygen blowing slag production method without generating dust or white smoke. In addition, by using the deoxidation refractory composition can be produced high clean steel.

Claims (15)

Core material; And A surface treatment layer surrounding the core material, The core material includes Al-containing material, Ca-containing material, silica flower, pearlite, Li-containing flux and binder, The surface treatment layer is a deoxidation refractory composition for producing a high clean steel that contains CaO. The method of claim 1, The core material is 20 to 50% by weight of Al-containing material, 20 to 40% by weight of Ca-containing material, 3 to 8% by weight of silica flower, 4 to 10% by weight of pearl rock, and 5 to 10% by weight of Li-containing flux. Deoxidation refractory composition for the production of high clean steel comprising% and 5 to 13% by weight binder. The method of claim 1, The Al-containing material is at least one selected from the group consisting of aluminum powder, aluminum chips and aluminum dross deoxidation refractory composition for manufacturing high-clean steel. The method of claim 1, The Ca-containing material is at least one member selected from the group consisting of CaO, Ca (OH) ₂ and CaCO ₃ Deoxidation refractory composition for manufacturing high clean steel. The method of claim 1, The Li-containing flux is at least one selected from the group consisting of spodumene (spodumene), petalite (petalite) and repidorite (Lithia mica) deoxidation refractory composition for high-clean steel production. delete The method of claim 1, The binder may be an inorganic binder including sodium silicate, calcium silicate and clay; And an organic binder comprising wheat flour, molasses, starch, and a resin. The method of claim 1, The core material is in the form of briquettes or pellets deoxidation refractory composition for the production of high clean steel. The method of claim 1, The surface treatment layer is formed on the surface of the core material to a thickness of less than 1mm deoxidation refractory composition for manufacturing high clean steel. A core material is prepared using a composition for forming a core material including an Al-containing material, a Ca-containing material, a silica flower, a pearlite, a Li-containing flux, and a binder, A surface treatment layer forming composition comprising CaO, a dispersion medium, a binder, a peptizing agent, and an antifoaming agent on the core material to form a surface treatment layer, comprising the step of forming a surface treatment layer. The method of claim 10, The composition for forming the surface treatment layer comprises a polyvinyl alcohol, polyvinylacetate, and a binder selected from the group consisting of a mixture thereof. The method of claim 1, The surface treatment layer is a deoxidation refractory composition for high clean steel production further comprising a binder, peptizing agent and antifoaming agent. The method of claim 12, The binder is selected from the group consisting of polyvinyl alcohol, polyvinylacetate, and mixtures thereof. The method of claim 12, The peptizing agent is selected from the group consisting of sodium tripolyphosphate, sodium hexametaphosphate, and mixtures thereof. The method of claim 12, The antifoaming agent is sodium naphthalene sulfite deoxidation refractory composition for producing high clean steel.