A pre-melting-free electroslag remelting slag system and its application method

Abstract

This invention discloses a pre-melting-free electroslag remelting slag system and its application method. The slag system consists of two parts: a base material and auxiliary materials. The base material is a pre-melted "Sanqi" slag. The auxiliary materials, by weight percentage, are: SiO2: 30%–50%, MgO: 30%–50%, M... x O y ≤15%, impurities ≤5%; the weight of the auxiliary material does not exceed 20% of the weight of the base material; M is the easily burnable element contained in the target steel grade, M x O y These are oxides of easily burnable elements. This invention allows for timely adjustments to the slag system during the production process, making the slag system more compatible with the steel grade or improving certain indicators such as burn-off rate, which is beneficial for stable electroslag production.

Description

Technical Field

[0001] This invention relates to the field of electrometallurgical technology, and in particular to a pre-melting electroslag remelting slag system and its application method. Background Technology

[0002] Electroslag remelting is a metallurgical technique that further purifies metals by allowing steel and slag to react fully. It utilizes the resistance heat generated by the high-temperature liquid slag to melt and refine the metal's consumable electrodes, followed by solidification in a water-cooled crystallizer. Remelted steel ingots possess advantages such as high purity, fine and uniform as-cast microstructure, and small, dispersed inclusions. Slag is a crucial raw material in electroslag metallurgy, playing a vital role in heating, refining, and ingot forming; its weight directly affects the final weight of the remelted steel ingot.

[0003] The industrial raw materials used in electroslag remelting slag include fluorite, lime, industrial alumina, quartz sand, magnesia, and titanium dioxide, with main components such as CaF2, CaO, Al2O3, MgO, SiO2, and TiO2. Once a suitable slag system is selected for the steel grade, its composition is essentially fixed. However, in actual production, the composition of certain steel grades often fluctuates, necessitating corresponding adjustments to the slag system. Therefore, this method allows for dynamic adjustment of the slag system composition to better match the steel grade or improve certain indicators such as burn-off rate. Summary of the Invention

[0004] The purpose of this invention is to provide a pre-melting electroslag remelting slag system and its application method, solving the problem that traditional pre-melting slag cannot adjust the slag composition and proportion according to the actual conditions of the electroslag remelting production site.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: a pre-melting-free electroslag remelting slag system, comprising two parts: a base material and auxiliary materials. The base material is a pre-melted "Sanqi" slag, and the auxiliary materials are composed of the following components by weight percentage: SiO2: 30%–50%, MgO: 30%–50%, M... x O y ≤15%, impurities ≤5%; the weight of the auxiliary material does not exceed 20% of the weight of the base material; M is the easily burnable element contained in the target steel grade, M x O y It is an oxide of an element that is easily burned.

[0006] Furthermore, the M x O y : 10% to 15%, the easily burnable elements include Ti, V, Mn and Zr.

[0007] Furthermore, the weight of the auxiliary material is not less than 5% of the weight of the base material.

[0008] Furthermore, the auxiliary materials are quartz sand and fused magnesia particles, wherein the quartz sand contains SiO2 with a purity of ≥99.5% and Fe2O3 with a purity of ≤0.02%; and the fused magnesia particles have a particle size of ≤5mm and contain MgO with a purity of ≥97%.

[0009] Furthermore, the composition ratio of the "Sanqi" residue is CaF2 (70%) and Al2O3 (30%).

[0010] Furthermore, the pre-melting treatment involves heating and melting the Panax notoginseng residue, then holding it at a temperature 50–100°C above its melting point for 30–50 minutes to fully remove internal impurities and moisture. After cooling and solidification, the residue is broken into particles ≤5mm.

[0011] A method for using a pre-melting electroslag remelting slag system includes the following steps:

[0012] (1) After preparing the auxiliary materials according to the above proportion, the auxiliary materials and the base materials are mixed evenly according to the above proportion. No pre-melting is required. The mixed slag is placed in a baking oven to dry and remove the crystal water.

[0013] (2) Place the conductive block on the bottom plate, then spread the baked slag from (1) evenly on the bottom plate, keeping the thickness of the spread even with the conductive block. Insert the consumable electrode into the crystallizer and ensure that the front end of the consumable electrode is in contact with the conductive block. Finally, add the baked slag all at once, start the power supply to heat and melt the conductive block, and complete the melting of the slag.

[0014] Furthermore, the baking oven has a baking temperature of 600–800°C and a baking time of 2–5 hours.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The present invention discloses a pre-melting electroslag remelting slag system and its application method, which eliminates the steps of vertical furnace sintering and crushing required by traditional multi-element slag systems, simplifies the process, reduces costs, and allows for the adjustment of the slag pool composition at any time according to the requirements of the remelted steel grade. The purpose of melting the slag material is achieved by the heat of the electric arc itself, which shortens the melting time, reduces power consumption, and reduces environmental pollution.

[0017] 1. Since the slag material of this invention is composed of two parts, base material and auxiliary material, and the composition of auxiliary material components and the ratio range of base and auxiliary material are given, the slag material composition and ratio can be adjusted at any time before electroslag remelting. Therefore, the slag can be prepared according to the requirements of the slag system for the remelted steel grade, which is suitable for the production needs of multiple steel grades and expands the application range of the slag system.

[0018] 2. Since the slag material of this invention is composed of two parts, base material and auxiliary material, there is no need to carry out vertical furnace sintering, crushing and other steps in the slag preparation process, which simplifies the process and reduces costs.

[0019] 3. By adding an appropriate amount of easily burnable element oxide M to the slag system x O y The auxiliary materials can effectively reduce the burn-off of easily oxidized elements, and the burn-off rate can be controlled to <5%. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. To further describe this invention, the following embodiments provide a more detailed description:

[0021] This invention discloses a composite pre-melting-free electroslag remelting slag system, comprising two parts: a base material and auxiliary materials. The base material is a pre-melted "three-seven" slag, with a composition ratio of CaF2 (70%) and Al2O3 (30%). The auxiliary materials are silica sand (SiO2) and fused magnesia particles (MgO). If the target steel grade contains easily burnable elements (such as Ti, V, Mn, Zr, etc.), an appropriate amount of easily burnable element oxides M can be added. x O y To reduce the degree of burn-off; M refers to the easily burnable element contained in the target steel grade, M x O y It is an oxide of an easily burnable element. The components in the auxiliary material, by weight percentage, are: SiO2: 30%–50%; MgO: 30%–50%; M... x O y 10%–15%, with the remainder being impurities ≤5%.

[0022] The weight of the slag-based auxiliary materials shall not exceed 20% of the weight of the base material; the purity of the quartz sand (SiO2) shall be ≥99.5%, and the Fe2O3 content shall be ≤0.02%; the particle size of the fused magnesia shall be ≤5mm, and the purity shall be ≥97%.

[0023] The method of using this pre-melting-free electroslag remelting slag system includes the following steps:

[0024] 1. Mixing and drying of slag: After weighing and preparing the above raw materials according to the required weight percentage, the auxiliary materials can be directly and uniformly mixed with the base material without pre-melting. The mixed slag is then placed in a baking oven to dry and remove the water of crystallization. The baking temperature is 600-800℃ and the baking time is 2-5 hours.

[0025] 2. Place the conductive block on the bottom plate, then spread the baked slag evenly on the bottom plate, keeping the thickness level with the conductive block. Insert the consumable electrode into the crystallizer, ensuring that the tip of the consumable electrode is in contact with the conductive block. Finally, add the baked slag all at once, turn on the power to heat and melt the conductive block, and complete the melting of the slag.

[0026] 3. All other operations shall be carried out in accordance with the standard procedures.

[0027] To further describe the present invention, the following detailed description is provided in conjunction with an example of a 40t slab electroslag furnace in a steel enterprise:

[0028] Example 1:

[0029] The target steel grade is vanadium-containing alloy steel. In this embodiment, a pre-melting-free electroslag remelting slag system consists of two parts: a base material and auxiliary materials. The base material is a pre-melted "three-seven" slag. The components of the auxiliary materials are as follows by weight percentage: SiO2: 47%; MgO: 40%; V2O5: 11%, with the remainder being impurities. The weight percentage of the base material to the auxiliary materials is 5:1.

[0030] The method of using this pre-melting-free electroslag remelting slag system includes the following steps:

[0031] 1. Mixing and drying of slag: After preparing the auxiliary materials according to the above proportions, mix the auxiliary materials directly with the base material according to the above proportions. No pre-melting is required. Place the mixed slag in a baking oven to dry and remove the crystal water. The baking temperature is 600℃ and the baking time is 4 hours.

[0032] 2. Spread the baked slag evenly on the surface of the base plate as bottom slag, until the conductive block is completely buried. After the bottom slag is laid, add the molten slag all at once and use its own electric arc heat to start the arc and melt the slag.

[0033] 3. All other operations shall be carried out in accordance with the standard procedures.

[0034] Electroslag ingots smelted using this slag system have a smooth and good surface, uniform internal structure, and meet the standards for porosity and segregation. The vanadium burn-off rate is 3.2%, which effectively controls the vanadium element burn-off.

[0035] Example 2:

[0036] The target steel grade is high manganese steel. In this embodiment, a pre-melting-free electroslag remelting slag system consists of two parts: a base material and auxiliary materials. The base material is a pre-melted "three-seven" slag. The components of the auxiliary materials are as follows by weight percentage: SiO2: 40%; MgO: 45%; MnO: 12%, with the remainder being impurities. The weight percentage of the base material to the auxiliary materials is 8:1.

[0037] The method of using this pre-melting-free electroslag remelting slag system includes the following steps:

[0038] 1. Mixing and drying of slag: After preparing the auxiliary materials according to the above proportions, mix the auxiliary materials directly with the base material according to the above proportions. No pre-melting is required. Place the mixed slag in a baking oven to dry and remove the water of crystallization. The baking temperature is 700℃ and the baking time is 3 hours.

[0039] 2. Spread the baked slag evenly on the surface of the base plate as bottom slag, until the conductive block is completely buried. After the bottom slag is spread, add the molten slag all at once and use its own electric arc heat to start the arc and melt the slag.

[0040] 3. All other operations shall be carried out in accordance with the standard procedures.

[0041] Electroslag ingots smelted using this slag system have a smooth and good surface, uniform internal structure, and meet the standards for porosity and segregation. The manganese burn-off rate is 3.5%, which effectively controls the loss of manganese elements.

[0042] Example 3:

[0043] The target steel grade is titanium alloy steel. In this embodiment, a pre-melting-free electroslag remelting slag system consists of two parts: a base material and auxiliary materials. The base material is a pre-melted "three-seven" slag. The components of the auxiliary materials are as follows by weight percentage: SiO2: 45%; MgO: 48%; TiO2: 6%, with the remainder being impurities. The weight percentage of the base material to the auxiliary materials is 10:1.

[0044] The method of using this pre-melting-free electroslag remelting slag system includes the following steps:

[0045] 1. Mixing and drying of slag: After preparing the auxiliary materials according to the above proportions, mix the auxiliary materials directly with the base material according to the above proportions. No pre-melting is required. Place the mixed slag in a baking oven to dry and remove the water of crystallization. The baking temperature is 800℃ and the baking time is 2 hours.

[0046] 2. Spread the baked slag evenly on the surface of the base plate as bottom slag, until the conductive block is completely buried. After the bottom slag is spread, add the molten slag all at once and use its own electric arc heat to start the arc and melt the slag.

[0047] 3. All other operations were performed according to conventional processes. Electroslag ingots smelted using this slag system exhibited a smooth surface, uniform internal structure, and met standards for porosity and segregation. The titanium burn-off rate was 2.8%, effectively controlling titanium element loss.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A pre-melting-free electroslag remelting slag system, characterized in that, It consists of two parts: base material and auxiliary materials. The base material is "Sanqi" slag after pre-melting treatment. The components of the auxiliary materials are as follows by weight percentage: SiO2: 30%~50%, MgO: 30%~50%, M x O y ≤15%, impurities ≤5%; the weight of the auxiliary material does not exceed 20% of the weight of the base material; M is the easily burnable element contained in the target steel grade, M x O y The auxiliary materials are easily burned oxides; after the auxiliary materials are prepared according to the above proportions, the auxiliary materials and the base materials are mixed evenly according to the above proportions without pre-melting, and the mixed slag is placed in a baking oven to dry and remove the crystal water; the pre-melting treatment is to heat and melt the "Sanqi" slag and keep it at a temperature 50~100℃ higher than the melting point for 30~50 minutes to fully remove its internal impurities and moisture, and then cool and solidify it, and crush it into particles ≤5mm.

2. The pre-melting-free electroslag remelting slag system according to claim 1, characterized in that, The M x O y The content is 10% to 15%, and the easily burnable elements include Ti, V, Mn, Zr, etc.

3. The pre-melting-free electroslag remelting slag system according to claim 1, characterized in that, The weight of the auxiliary material shall not be less than 5% of the weight of the base material.

4. A pre-melting-free electroslag remelting slag system according to any one of claims 1 to 3, characterized in that, The auxiliary materials are quartz sand and fused magnesia particles. The quartz sand contains SiO2 with a purity of ≥99.5% and Fe2O3 with a purity of ≤0.02%. The fused magnesia particles have a particle size of ≤5mm and contain MgO with a purity of ≥97%.

5. The pre-melting-free electroslag remelting slag system according to claim 1, characterized in that, The composition ratio of the "Sanqi" residue is CaF2:70% and Al2O3:30%.

6. A method of using the pre-melting-free electroslag remelting slag system according to any one of claims 1 to 5, characterized in that, Place the conductive block on the bottom plate, then spread the baked slag evenly on the bottom plate, keeping the thickness level with the conductive block. Insert the consumable electrode into the crystallizer, ensuring that the tip of the consumable electrode is in contact with the conductive block. Finally, add the baked slag all at once, start the power supply to heat and melt the conductive block, and complete the melting of the slag.

7. The method of using the pre-melting-free electroslag remelting slag system according to claim 6, characterized in that, The baking temperature is 600~800℃, and the baking time is 2~5h.