CN1598001A

CN1598001A - Compound dooxidizing agent and its production process

Info

Publication number: CN1598001A
Application number: CNA2004100540364A
Authority: CN
Inventors: 丁建章
Original assignee: Shenheng Environmental Protection Science & Technology Service Co Ltd Shangh
Current assignee: Shenheng Environmental Protection Science & Technology Service Co Ltd Shangh
Priority date: 2004-08-26
Filing date: 2004-08-26
Publication date: 2005-03-23

Abstract

The invention relates to a kind of complex deoxidizer and its producing method. Its character is that the complex deoxidizer in question is mainly composed by aluminum ash and active material, among which the percentage of the active material is 6-10%. The percentage of the components in the aluminum ash is that the metal aluminum occupies 13-18%; Al2O3 occupies 65-75%; the percentage of SiO2 should be less than 6%; the percentage of MgO should be less than 1.5%. The advantage is that markedly decrease the content of FeO in the steel residue; ensure the purity of molten steel; decrease the cost of steel-making.

Description

Composite deoxidizer and production method thereof

Technical Field

The invention relates to metallurgy, in particular to a composite deoxidizer and a production method thereof.

Background

According to the research of metallurgical experts at home and abroad for many years, the [ O]in the steel at the steelmaking temperature is discovered]Mainly by [ FeO]There is a way to remove [ O]in steel]The conventional single-metal deoxidation method is usually adopted, namely Al, Si, Mn, C and the like, and the steelmaking theory indicates that Al in the steel₂O₃The inclusions are usually Al deoxidized products, and when metallic Al is added into molten steel, [ O]in the steel is caused by the strong deoxidizing capacity of the metallic Al](mainly, [ FeO]]) Combine with Al to form Al₂O₃The inclusions are dispersed, and floating of large crystal nuclei is difficult, but usually, argon blowing stirring and the like must be enhanced and the time for sufficient retention is not allowed until Al remaining in the steel₂O₃Gradually float upwards. On the other hand, when aluminum is added to steel, a part of residues may exist in molten steelAluminum, which is combined with oxygen in the air during the casting of molten steel to form Al₂O₃This is the secondary oxidation. Because the grains of the secondary oxidized inclusion are smaller and more dispersed, and the floating time is insufficient, Al formed at the stage₂O₃Most of the inclusions remain in the steel, or Al remains in the steel₂O₃The main source of inclusions.

C. Si is a common deoxidizer and an alloy element of molten steel, a certain C, Si content can ensure the service performance of steel, and the Si is an indispensable element in the steel. However, in the smelting process, C, Si in the molten steel is in danger of being qualified because the content of [ O]in the molten steel is difficult to control. Therefore, it is required in factories to ensure that the [ O]content in steel is not more than the lower limit and the yield of C, Si is stabilized.

Therefore, although the conventional single-metal deoxidation method has the advantages of rapid deoxidation, good steel slag surface coverage, convenient smelting and use and the like, the method has the defects of long floating time in steel, easy secondary oxidation of excessive metal in molten steel, difficult discharge of secondary oxidation inclusions and direct influence on the quality of the steel. In addition, the material is easy to burn and damage in use, the practical effect is affected, and the material is expensive, so that the production cost is high.

Disclosure of Invention

The invention aims to provide a composite deoxidizer and a production method thereof according to the defects of the prior art, wherein the recovered aluminum ash is processed, added with active elements and auxiliary raw materials and activated to prepare powder, and the composite deoxidizer contains Al which can be strongly deoxidized and activated metal oxides, and is a composite deoxidizer with excellent performance.

The aluminum ash is 3-5% of waste slag generated in aluminum smelter, and the collected waste slag ash mainly contains Al₂O₃Besides, it also contains a part of metallic aluminium and its impurity.

The purpose of the invention is realized by the following technical scheme:

a composite deoxidant and its production method are characterized by that said composite deoxidant is mainly formed from aluminium ash and active substance, in which the active substance is (6-10)%.

The composite deoxidizer comprises the following components in percentage by weight: metal Al accounts for (13-18)%, Al₂O₃65-75 percent of silicon dioxide SiO₂The proportion of the magnesium oxide and the MgO is less than 6 percent, the proportion of the magnesium oxide and the MgO is less than 5 percent, and the proportion of the carbon C is less than 1.5 percent.

The active substance in the components of the compound deoxidizer adopts a composition of fluoride and chloride, the proportion of the fluoride and the chloride is 1: 1, wherein the fluoride and the chloride usually adopt sodium fluoride and magnesium chloride.

The production method of the compound deoxidizer comprises the following steps: crushing and ball-milling the aluminum ash raw material, adding active substances into the aluminum ash raw material, performing activation treatment in an activation treatment device, and finally drying and baking the aluminum ash raw material until the water content is less than 1%.

Wherein the step of crushing and ball milling the aluminum ash raw material refers to crushing and ball milling the aluminum ash raw material to 80-100 meshes.

The invention has the advantages of greatly reducing FeO in the steel slag, ensuring the purification of molten steel, reducing smelting cost, and only reducing the cost by one third of the original cost.

Brief description of the drawings

FIG. 1 is a schematic view of the process of the present invention;

FIG. 2 is a schematic flow chart of the equipment of the embodiment of the invention:

specific technical scheme

The features of the present invention and other related features are described in further detail below by way of example in conjunction with the following drawings to facilitate understanding by those skilled in the art:

the composite deoxidizer in the embodiment mainly comprises aluminum ash, active substances and auxiliary raw materials, wherein the active substances account for 6% and the auxiliary raw materials account for 3-5% generally.

In the above aluminum ash: metal Al accounts for (13-18)%, Al₂O₃65-75 percent of silicon dioxide SiO₂The proportion of the magnesium oxide and the MgO is less than 6 percent, the proportion of the magnesium oxide and the MgO is less than 5 percent, and the proportion of the carbon C is less than 1.5 percent.

The active substance is a composition of sodium fluoride and magnesium chloride, and the ratio of the sodium fluoride to the magnesium chloride is 1: 1.

Rare earth compounds used as auxiliary materials, e.g. calcium fluoride CaF₂。

As shown in the process and equipment flow of FIGS. 1-2, the method for producing the compound deoxidizer of the embodiment comprises the following steps: firstly, the aluminum ash raw material is adjusted to the proportion, then the aluminum ash raw material is crushed and ball-milled to 80-100 meshes, 6 percent of active substance, namely a composition of sodium fluoride and magnesium chloride in a ratio of 1: 1 is added in an activation processor for activation treatment, and after the activation treatment, the auxiliary raw material CaF is added according to the proportion of 3.5 percent₂Then dried, baked and deodorized (NH)₃) The process removes ammonia smell from the AD powder, and the water content after drying is less than 1 percent, thus the product is qualified.

The active substances, i.e. the composition of sodium fluoride and magnesium chloride in the ratio of 1: 1, are added for activation treatment, so as to activate the main component Al in the aluminum ash₂O₃To make it: (1) the melting point is reduced from the original melting point of 2030 ℃ to about 1020 ℃, so that the steel is easy to melt and is beneficial to reacting with molten steel; (2) al in the component₂O₃、MgO、SiO₂After activation treatment, the slag former is changed into a multi-elementpremelting slag former, which can lead CaO in steel to generate calcium aluminate and adsorb [ O]in molten steel]And impurities, and the floating and gathering rise plays roles in deoxidation, desulfurization and purification of water. This is a superior performance to deoxidation with pure Al.

Adding CaF as an auxiliary raw material₂The product of the embodiment has the effects of reducing the fluidity and the melting point of reactants in the reaction with a desulfurizing agent in molten steel, and easily realizing slagging, adsorption and rising.

The product of the embodiment has the following physical properties by detection:

bulk density: 0.9g/cm³

Melting point: 1020 deg.C

The reaction mechanism of the product of the present example is:

the product contains 13-18% of metal Al, and Al can be mixed with [ O]in steel]And [ O]in slag]Reaction to Al₂O₃And combining at the steelmaking temperature, and standard free energy generation is as follows:

ΔF°＝401500+76.917(CaL/MoL)

according to the deoxidation characteristics of the elements, the deoxidation capability of the elements is Al&gtSi&gtMn, and therefore, the deoxidation capability of Al is strongest.

In the process of steelmaking, because of adopting high alkaline operation, (CaO) in the slag can obviously reduce SiO₂、TiO₂、Al₂O₃Activity of (b), thereby increasing [ Ti]、[Al]、[Si]The deoxidation ability of (A). The product of the embodiment hasIs beneficial to playing the role of the alkaline slag and improving the deoxidation capability of the alkaline slag.

When the product of this example is added to molten steel, Al therein is in contact with [ O]in the steel]Reaction to remove O from steel]And activated Al₂O₃、SiO₂MgO is quickly mixed with [ FeO]in steel under the action of active substances in the product of the embodiment]And combining to form a large mixed oxide.

Activation of

The interfacial tension between them and oxide inclusion in steel is small, melting point is low, and they are easy to mutually adsorb and converge, and quickly float upwards, so that it can reduce FeO in steel and reduce O in steel.

On the other hand, the content of [ FeO]in slag is an important index (slag-steel balance theory) for weighing [ O]in steel, and in order to ensure the reduction of [ FeO]in slag, reducing slag is generally prepared, which not only ensures the reduction of [ FeO]content in slag, but also has good activity, and can effectively capture metal oxide inclusion in steel, thereby achieving the purpose of purifying molten steel. Because the AD powder has stronger deoxidizing capacity and higher activity, the [ FeO]in slag can be effectively removed, the slag and slag pile structure is reasonable and active, and the slag modifier has stronger inclusion catching capacity, and is a good slag modifier.

From CaO-SiO₂-Al₂O₃The ternary phase diagram shows that calcium aluminate [ MCaO nAl2]is very easily formed when the content of SiO2 is low]. Calcium aluminate has a much lower melting point than calcium silicate and [ S]is]The diffusion speed in calcium aluminate is 2-4 times of that in common slag system, and S in steel can be greatly removed]And (4) content. The desulfurization capability of the steel slag isimproved.

In addition, CaO-SiO₂-Al₂O₃the-MgO slag system has the characteristics of activity, stability, large gas-barrier capacity, strong reducing capacity, easy temperature control, small foam of sulfur powder and the like, has good covering effect on the surface of the steel ladle, and is good covering slag.

The product of the embodiment solves the problem of Al in the prior art₂O₃And inclusion problems in steel, and C, Si problems in steel:

al in the product of this example₂O₃After the alloy is added into molten steel, no inclusion is formed. First, the Al is₂O₃Is a relatively stable compound, can not be decomposed at the steelmaking temperature, can not be recombined after being decomposed in the smelting process, and can not form dispersed Al after Al deoxidation in the prior art₂O₃(ii) a Second, solid Al₂O₃After entering molten steel, the molten steel continuously floats upwards in the melting process due to the larger granularity and cannot be remained in the steel; third, Al having a larger particle size₂O₃Can be mixed with other metal oxides CaO, SiO in steel₂]The combination of the three elements, four elements and multi elements forms ternary, quaternary and multi elements oxides with larger volume and lower melting point, and the floating is easier, namely, molten steel is adopted to pass through slag liquid (Al in slag) during electroslag smelting₂O₃More than 30%), whereas non-metallic inclusions in molten steel are rather reducedThe principle of (1).

The Al in the product is solid solution Al, but not single metal Al, and contains a large amount of activated Al₂O₃(ii) a The deoxidation products are easily eliminated during deoxidation, and they carry other deoxidation products (such as SiO)₂MnO) together floating abilityTherefore, the inclusion in the steel is not increased.

With respect to the C, Si problem in steel:

the use of the product of the embodiment enables us to better solve the problem, and by adding the product into molten steel, the [ O]in the molten steel is reduced to a lower limit, the AD hardly contains C, Si, and the C, Si acquisition rate is relatively stable, so that more low-price high-carbon alloy can be used in the smelting process. When low-carbon steel is smelted, the product of the embodiment is more excellent in application.

The product of the embodiment is simple multi-element pre-melted slag, has the common advantages of the pre-melted slag, but can obtain good effect by adding other slag materials according to the requirements of steel types.

Claims

1. A composite deoxidant and its production method are characterized by that said composite deoxidant is mainly formed from aluminium ash and active substance, in which the active substance is (6-10)%.

2. The compound deoxidizer and the production method thereof according to claim 1 are characterized in that the aluminum ash in the components of the compound deoxidizer accounts for the following components: metal Al accounts for (13-18)%, Al₂O₃65-75 percent of silicon dioxide SiO₂The proportion of the magnesium oxide and the MgO is less than 6 percent, the proportion of the magnesium oxide and the MgO is less than 5 percent, and the proportion of the carbon C is less than 1.5 percent.

3. The compound deoxidizer andthe production method thereof according to claim 1, wherein the active material in the components of the compound deoxidizer is a combination of fluoride and chloride, and the ratio of the two is 1: 1.

4. The compound deoxidizer of claim 1 or 3, wherein the fluoride and the chloride are sodium fluoride and magnesium chloride.

5. The compound deoxidizer and the production method thereof according to claim 1 are characterized in that the production method of the compound deoxidizer is as follows: crushing and ball-milling the aluminum ash raw material, adding active substances into the aluminum ash raw material, performing activation treatment in an activation treatment device, and finally drying and baking the aluminum ash raw material until the water content is less than 1%.

6. The compound deoxidizer and the production method thereof according to claim 1, wherein the crushing and ball milling treatment of the aluminum ash raw material is to crush and ball mill the aluminum ash raw material to 80-100 mesh size.

7. The compound deoxidizer and the production method thereof according to claim 1 or 5, characterized in that the aluminum ash raw material after activation treatment in the production method of the compound deoxidizer is added with a rare earth compound.

8. The compound deoxidizer of claim 1 or 5, and a production method thereof, wherein the aluminum ash raw material after activation treatment in the production method of the compound deoxidizer is added with a rare earth compound CaF₂。

9. The compound deoxidizer ofclaim 1 or claim 5, wherein the compound deoxidizer is produced by deodorizing NH gas in the product₃And (4) removing.