Preparation and use method of composite deoxidizer for LF slagging

Abstract

The invention belongs to the field of steelmaking refining, relates to a preparation and use method of a complex deoxidizer for LF slagging, and aims to solve the problems that the existing complex deoxidizer containing elements such as calcium, magnesium, barium, strontium, sodium and potassium is difficult to detect and analyze, the quality is difficult to guarantee, low-melting-point inclusions are formed in steel, the cleanliness of molten steel is influenced, and the molten steel cannot be cleaned easily. According to the invention, the steel ladle top slag after converter or electric furnace tapping is subjected to deoxidation modification, and the desulfurization, deoxidation and inclusion removal functions are improved. The steel slag deoxidizing agent is scientific and reasonable in chemical component design, good in physical performance, wide in material source, simple to prepare, rapid in steel slag deoxidizing, obviously improved in molten steel cleanliness and low in application cost.

Description

Technical Field

[0001] The invention belongs to the field of steelmaking and refining, and relates to a method for preparing and using a composite deoxidizer for LF slag making. Background Art

[0002] White slag refining is a special refining function of LF. Its main purpose is to deoxidize and modify the ladle top slag after steel is tapped from the converter or electric furnace, and to improve the desulfurization, deoxidation and inclusion removal functions of the ladle slag, thereby improving the cleanliness of molten steel and improving the quality of molten steel. Generally, LF refining slag deoxidizers use carbon, aluminum, silicon, manganese and other alloys alone, or use a variety of alloys to form a composite deoxidizer, which contains strong deoxidizing elements such as calcium, magnesium, barium, strontium, sodium, and potassium. The latest research has found that composite deoxidizers containing calcium, magnesium, barium, strontium, sodium, potassium and other elements are difficult to detect and analyze, and quality assurance is difficult. During the LF refining process, low-melting-point inclusions will be formed in the steel, which is not conducive to the cleanliness control of molten steel. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a method for preparing and using a composite deoxidizer for LF slag making, which can make full use of alloy raw materials that are easily available on the market. The preparation method is simple and efficient, and the quality control of the deoxidizer is easy. The use of LF white slag can efficiently make white slag, avoid its adverse effects, improve the cleanliness of molten steel, and reduce the quality risks of steel billets and steel plates.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for preparing and using a composite deoxidizer for LF slag making, comprising the following steps:

[0005] S1, ingredients; the raw materials are carbon powder, aluminum particles, ferrosilicon powder, and silicon carbide powder, and these raw materials are mixed according to the mass percentage of C = 35-45%, Si = 20-30%, and Al ≥ 20%, while ensuring that H2O ≤ 0.5%, and no calcium, magnesium, barium, strontium, sodium, and potassium are added. The finished product is dry and clean, and no foreign inclusions are allowed;

[0006] S2, the preparation method adopts a mechanical stirring and mixing production process, the proportioned raw materials are finely stirred and mixed by a mixer to ensure that the materials are uniform and the particle size range is ≤3mm, and a composite deoxidizer for LF slag making is obtained;

[0007] S3, mix the materials and pack them into 3-5kg / bag. Small loans are packed in double-layer moisture-proof packaging, and concentrated bags are packed in moisture-proof packaging. The outer packaging is made of corrosion-resistant and unbreakable polypropylene material, and the inner lining is packed in moisture-proof packaging with plastic film. The net weight of the product is 1 ton. The outer packaging bag is marked with product name, manufacturer, production date, net weight and other product information;

[0008] S4, the method of use includes, during the LF refining process, firstly feeding molten steel into a refining furnace, opening the bottom of the ladle to blow argon for stirring, adding lime for slag making, and after the slag is melted, adding the composite deoxidizer into the ladle at a ratio of 0.5 to 0.8 kg per ton of steel, and then heating the electrode within 8 minutes to achieve the content of FeO and MnO in the ladle slag ≤1%, thereby achieving a white slag refining effect.

[0009] Optionally, in step S1, the carbon powder has a C content ≥92%, an S content ≤0.20%, and a particle size range ≤3mm; the aluminum particles have an Al content ≥98% and a particle size range ≤3mm; the ferrosilicon powder has a Si content ≥72% and a particle size range ≤3mm.

[0010] Optionally, the silicon carbide uses silicon carbide SiC ≥ 75% and a particle size range of ≤ 3 mm.

[0011] Optionally, the raw materials of the composite deoxidizer for slag making of every 1000kg LF are: carbon powder = 300-350kg, aluminum particles = 240-260kg, ferrosilicon powder = 30-80kg, silicon carbide powder = 400-500kg.

[0012] Optionally, in step S4, by controlling the refining conditions, the Al increase in the molten steel is ≤0.001%, the Si increase is ≤0.01%, the C increase is ≤0.01%, the N increase is ≤5ppm, the H increase is ≤1ppm, the process desulfurization rate is ≥85%, and the total oxygen content of the molten steel is ≤25ppm, thereby improving the cleanliness and quality of the molten steel.

[0013] The beneficial effects of the present invention are as follows: the preparation and use method of the composite deoxidizer for LF slag making of the present invention has the advantages of scientific and reasonable chemical composition design, good physical properties, wide material acquisition, simple preparation, rapid slag deoxidation, significant improvement in molten steel cleanliness, low application cost, and ideal practical effect.

[0014] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. DETAILED DESCRIPTION

[0015] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0016] A method for preparing and using a composite deoxidizer for LF slag making comprises the following steps:

[0017] S1, ingredients; the raw materials are carbon powder, aluminum particles, ferrosilicon powder, and silicon carbide powder, and these raw materials are mixed according to the mass percentage of C = 35-45%, Si = 20-30%, and Al ≥ 20%, while ensuring that H2O ≤ 0.5% (adsorbed water), and no calcium, magnesium, barium, strontium, sodium, and potassium elements are added. The finished product is dry and clean, and no foreign inclusions are allowed to be mixed;

[0018] S2, the preparation method adopts a mechanical stirring and mixing production process, the proportioned raw materials are finely stirred and mixed by a mixer to ensure that the materials are uniform and the particle size range is ≤3mm, and a composite deoxidizer for LF slag making is obtained;

[0019] S3, mix the materials and pack them into 3-5kg / bag. Small loans are packed in double-layer moisture-proof packaging, and concentrated bags are packed in moisture-proof packaging. The outer packaging is made of corrosion-resistant and unbreakable polypropylene material, and the inner lining is packed in moisture-proof packaging with plastic film. The net weight of the product is 1 ton. The outer packaging bag is marked with product name, manufacturer, production date, net weight and other product information;

[0020] S4, the method of use includes, during the LF refining process, firstly feeding molten steel into a refining furnace, opening the bottom of the ladle to blow argon for stirring, adding lime for slag making, and after the slag is melted, adding the composite deoxidizer into the ladle at a ratio of 0.5 to 0.8 kg per ton of steel, and then heating the electrode within 8 minutes to achieve the content of FeO and MnO in the ladle slag ≤1%, thereby achieving a white slag refining effect.

[0021] In this embodiment, in step S1, the carbon powder has a C content ≥92%, an S content ≤0.20%, and a particle size range ≤3mm; the aluminum particles have an Al content ≥98% and a particle size range ≤3mm; the ferrosilicon powder has an Si content ≥72% and a particle size range ≤3mm.

[0022] In this embodiment, silicon carbide uses silicon carbide SiC≥75%, and the particle size range is ≤3 mm.

[0023] In this embodiment, the raw materials of the composite deoxidizer for slag making per 1000kg LF are: carbon powder = 300-350kg, aluminum particles = 240-260kg, ferrosilicon powder = 30-80kg, silicon carbide powder = 400-500kg.

[0024] In this embodiment, in step S4, by controlling the refining conditions, the Al increase in the molten steel is ≤0.001%, the Si increase is ≤0.01%, the C increase is ≤0.01%, the N increase is ≤5ppm, the H increase is ≤1ppm, the process desulfurization rate is ≥85%, and the total oxygen content of the molten steel is ≤25ppm, thereby improving the cleanliness and quality of the molten steel.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. The method for making and using a composite deoxidizer for LF slag making is characterized in that: The following steps are involved: S1, ingredients; the raw materials are carbon powder, aluminum particles, ferrosilicon powder, and silicon carbide powder, and these raw materials are mixed according to the mass percentage of C = 35-45%, Si = 20-30%, and Al ≥ 20%, while ensuring that H2O ≤ 0.5%, and no calcium, magnesium, barium, strontium, sodium, and potassium are added. The finished product is dry and clean, and no foreign inclusions are allowed; S2, the preparation method adopts a mechanical stirring and mixing production process, the proportioned raw materials are finely stirred and mixed by a mixer to ensure that the materials are uniform and the particle size range is ≤3mm, and a composite deoxidizer for LF slag making is obtained; S3, mix the materials and pack them into 3-5kg / bag. Small loans are packed in double-layer moisture-proof packaging, and concentrated bags are packed in moisture-proof packaging. The outer packaging is made of corrosion-resistant and unbreakable polypropylene material, and the inner lining is packed in moisture-proof packaging with plastic film. The net weight of the product is 1 ton. The outer packaging bag is marked with product name, manufacturer, production date, net weight and other product information; S4, the method of use includes, during the LF refining process, firstly feeding molten steel into a refining furnace, opening the bottom of the ladle to blow argon for stirring, adding lime for slag making, and after the slag is melted, adding the composite deoxidizer into the ladle at a ratio of 0.5 to 0.8 kg per ton of steel, and then heating the electrode within 8 minutes to achieve the content of FeO and MnO in the ladle slag ≤1%, thereby achieving a white slag refining effect.

2. The method for making and using the composite deoxidizer for LF slag making according to claim 1, characterized in that: In step S1, the carbon powder has a C content of ≥92%, an S content of ≤0.20%, and a particle size range of ≤3mm; the aluminum particles have an Al content of ≥98% and a particle size range of ≤3mm; the ferrosilicon powder has an Si content of ≥72% and a particle size range of ≤3mm.

3. The method for making and using the composite deoxidizer for LF slag making according to claim 1, characterized in that: Silicon carbide uses silicon carbide SiC ≥ 75%, and the particle size range is ≤ 3mm.

4. The method for making and using the composite deoxidizer for LF slag making according to claim 1, characterized in that: The raw materials of composite deoxidizer for slag making of every 1000kg LF are: carbon powder = 300-350kg, aluminum particles = 240-260kg, ferrosilicon powder = 30-80kg, silicon carbide powder = 400-500kg.

5. The method for making and using the composite deoxidizer for LF slag making according to claim 1, characterized in that: In step S4, by controlling the refining conditions, the Al increase in the molten steel is ≤0.001%, the Si increase is ≤0.01%, the C increase is ≤0.01%, the N increase is ≤5ppm, the H increase is ≤1ppm, the process desulfurization rate is ≥85%, and the total oxygen content of the molten steel is ≤25ppm, thereby improving the cleanliness and quality of the molten steel.