A high iron copper alloy continuous casting crystallizer protection slag and its preparation method and application

Abstract

The present invention relates to a high iron copper alloy continuous casting crystallizer protective slag and its preparation method and application. The protective slag comprises the following components by mass percentage: 8.62-25.86% CaO, 8.32-24.96% SiO2, 27.68-55.36% B2O3, 3.06-9.18% A12O3 and 12.32-24.64% Na2O. In the preparation method, each raw material is heated to obtain molten slag, which is then added into water for rapid cooling to obtain a glassy protective slag block, which is finally crushed and ground to obtain protective slag. The protective slag is used for the preparation of high iron copper alloy. As a continuous casting crystallizer protective slag, it has the characteristics of high viscosity, weak slag-metal interface reactivity, strong ability to absorb FeO and Fe2O3 inclusions, etc., and can be well used with copper-iron alloys with high casting temperatures.

Description

Technical Field

[0001] The invention belongs to the technical field of copper smelting and continuous casting, and specifically relates to a high-iron-copper alloy continuous casting crystallizer protection slag and a preparation method and application thereof. Background Art

[0002] Copper-iron alloy (Cu-Fe) is one of the new generation of high-strength conductive copper alloys. It has the advantages of high strength, electrical conductivity, thermal conductivity, electromagnetic wave shielding and low cost, and has broad development prospects. At present, there are three main types of crystallizer protection slags for semi-continuous casting of copper alloys: carbonaceous, molten salt and silicate. Carbonaceous mainly includes carbon black, graphite flakes, etc. Molten salts include borax + salt, 84% salt + 8% cryolite + 8% potassium chloride, etc., which are suitable for alloys with casting temperatures of about 1200°C and below. Silicates are rarely used, and molten glass is mainly used. The melting point of glass is about 800~1000°C, and it can be used for alloys with casting temperatures of about 1300~1350°C. The addition of solid protective agents to the crystallizer usually requires that its melting point is 250~300°C lower than the alloy casting temperature and has a suitable viscosity. However, the casting temperature of copper-iron alloy varies with the Fe content (5-18wt%), which exceeds the existing casting temperature of most copper alloys. The existing mold protection slag (molten salt and glass) has the problem of too low melting point and too low viscosity when used for casting, and the surface of the ingot has serious problems of cold shut, deep vibration marks and depression, resulting in large ingot milling loss. Therefore, it is necessary to design a new mold protection slag for high iron copper alloy continuous casting for production. Summary of the invention

[0003] The purpose of the present invention is to provide a high iron-copper alloy continuous casting crystallizer protection slag and its preparation method and application. The protection slag itself has the characteristics of high melting point and low viscosity, and can be well used with copper-iron alloys with high casting temperatures.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a high iron-copper alloy continuous casting crystallizer protection slag, which comprises the following components, by mass percentage: 8.62~25.86% CaO, 8.32~24.96% SiO2, 27.68~55.36% B2O3, 3.06~9.18% A12O3 and 12.32~24.64% Na2O.

[0005] Preferably, the polybasic basicity of the slag (CaO+2 Na2O) / (SiO2+Al2O3+B2O3) is in the range of 0.5-0.9, so that the viscosity of the slag changes moderately with temperature, thereby ensuring the amount of slag to be discharged.

[0006] Preferably, the total mass ratio of the CaO, SiO2, and A12O3 to the total mass ratio of the B2O3 and Na2O is 0.25-1.5, so that the mold slag has a relatively low melting temperature.

[0007] The viscosity of the protective slag at 1200℃ is 0.1~0.7Pa.s.

[0008] A method for preparing a high iron copper alloy continuous casting crystallizer protective slag comprises weighing raw materials according to the mass percentage of each component of the protective slag and mixing them evenly, heating and melting to obtain molten slag, pouring the molten slag into water and quenching to obtain a glassy protective slag block, drying and then crushing and grinding to a particle size of ≤200 mesh to obtain a high iron copper alloy continuous casting crystallizer protective slag.

[0009] The present invention further proposes the application of the high iron copper alloy continuous casting crystallizer protection slag for the high iron copper alloy preparation process, wherein the mass percentage of Fe in the high iron copper alloy is 5-18%, and the mass percentage of Si is 0-1%.

[0010] The principle of the present invention is analyzed as follows: 1. The protective slag prepared by the present invention adopts Na2O-B2O3 as the base, and the content of A12O3 is less than 9%, the slag-gold interface reactivity is weak, and the degree of high melting point oxide formed by FeO or Fe2O3 and A12O3 in the alloy liquid is reduced. The polybasic basicity (CaO+2 Na2O) / (SiO2+Al2O3+B2O3) is in the range of 0.5-0.9, the basicity is reasonable, and the slag viscosity changes slowly with temperature, thereby ensuring the appropriate slag amount of the liquid protective slag in the crystallizer.

[0011] 2. SiO2 and B2O3 in the protective slag act as network structure formers, which directly affect the viscosity of the slag system. The mass ratio of (CaO+2 Na2O) / (SiO2+Al2O3+B2O3) remains stable, and the viscosity of the slag system is stable.

[0012] 3. The addition of B2O3 in the protective slag can, on the one hand, react with the main impurity oxides FeO and Fe2O3 in the copper-based iron alloy to form low-melting-point compounds, which can not only effectively remove impurities in the copper-iron alloy and ensure the quality of the finished product, but also ensure that the melting point and viscosity of the slag do not fluctuate significantly, thereby ensuring a good uniformity of the internal structure of the finished ingot. On the other hand, it can promote the absorption of FeO and Fe2O3 inclusions in copper and purify the copper liquid.

[0013] 4. The additive A12O3 in the protective slag is to ensure that the viscosity of the slag can be maintained at around 0.1~0.7Pa.s under high temperature conditions (greater than 1200℃).

[0014] The beneficial effects of the present invention are as follows: the high iron copper alloy continuous casting crystallizer protection slag provided by the present invention has the advantages of weak slag-metal interface reactivity, stable properties, strong ability to absorb Al2O3, FeO and Fe2O3 inclusions, etc. Under the condition of low total mass ratio of (CaO+SiO2+A12O3) / (B2O3+Na2O), the protection slag has a small tendency to crystallize, which is conducive to promoting heat transfer and facilitating the formation of the shell in the initial solidification area of ​​the crystallizer; at the same time, its physical and chemical properties such as viscosity and melting temperature can meet the continuous casting requirements of high iron copper alloy ([Fe]=5-18%, [Si]=0-1%), and good liquid slag fluidity can meet the lubrication requirements, thereby reducing the occurrence of copper leakage accidents. . DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below in conjunction with the embodiments, but they are not intended to limit the invention in any way.

[0016] Example 1: A high iron copper alloy continuous casting crystallizer protection slag, comprising the following components by mass percentage: CaO 8.6%, SiO2 8.7%, B2O3 55.0%, A12O3 3.2%, and Na2O 24.5%.

[0017] Preferably, the mass ratio of (CaO+2Na2O) / (SiO2+Al2O3+B2O3) is 0.86; the mass ratio of (CaO+SiO2+A12O3) / (B2O3+Na2O) is 0.26.

[0018] The preparation process of the protective slag is as follows: the above-mentioned protective slag raw materials are weighed according to the target components, and mechanically stirred to make the components fully and evenly mixed; then the mixed sample is added into a submerged arc furnace and heated to 1250°C to melt, and volatiles and gas substances are removed. After it is melted, it is stirred evenly and kept warm for 10 minutes to form a molten melt between the components; the molten melt is poured into water and quenched to obtain a glassy protective slag block, and the glassy protective slag block is dried and then mechanically crushed and ground to a particle size of ≤200 mesh to obtain a high-iron-copper alloy continuous casting crystallizer protective slag powder.

[0019] Example 2: A high iron-copper alloy continuous casting crystallizer protection slag comprises the following components, by mass percentage: CaO 18.8%, SiO2 16.6%, B2O3 48.5%, A12O3 6.1%, and Na2O 10%.

[0020] The preferred mass ratio of (CaO+2Na2O) / (SiO2+Al2O3+B2O3) is 0.54; the preferred mass ratio of (CaO+SiO2+A12O3) / (B2O3+Na2O) is 0.71.

[0021] The method for preparing the protective slag is the same as that in Example 1.

[0022] Example 3: A high iron-copper alloy continuous casting crystallizer protection slag comprises the following components, by mass percentage: CaO 23.8%, SiO2 26.6%, B2O3 33.5%, A12O3 6.1%, and Na2O 10%.

[0023] Preferably, the mass ratio of (CaO+2Na2O) / (SiO2+Al2O3+B2O3) is 0.66; the mass ratio of (CaO+SiO2+A12O3) / (B2O3+Na2O) is 1.30.

[0024] The method for preparing the protective slag is the same as that in Example 1.

[0025] Comparative Example 1: This comparative example uses the current mold protection slag for brass continuous casting, which includes the following components by mass percentage: B2O3 69.3%, Na2O 30.8%.

[0026] Among them, the mass ratio of (CaO+2Na2O) / (SiO2+Al2O3+B2O3) is 0.44; the mass ratio of (CaO+SiO2+A12O3) / (B2O3+Na2O) is 0.

[0027] The mold slag in this example has a low melting point and low viscosity at high temperatures. The mold slags of Examples 1 to 3 and Comparative Example 1 were used for semi-continuous casting of a copper alloy containing 5.0% Fe. The main physical properties of the mold slag are shown in Table 1.

[0028] Table 1 Main physical properties of the crystallizer covering agent in each embodiment

[0029]

[0030] It can be seen from the above table that the high iron-copper alloy continuous casting crystallizer protection slag provided by the present invention has a high melting point and high-temperature viscosity, can be well matched with copper-iron alloys, the melting temperature is in the range of 850~1041℃, and the viscosity is in the range of 0.15~0.66Pa.s at 1200℃, which meets the continuous casting requirements of the alloy.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation modes of the present invention may be modified or replaced by equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. A high iron copper alloy continuous casting mold protection slag, characterized in that: In terms of mass percentage, it includes the following components: 8.62~25.86% CaO, 8.32~24.96% SiO2, 27.68~55.36% B2O3, 3.06~9.18% A12O3 and 12.32~24.64% Na2O.

2. The high iron-copper alloy continuous casting mold protection slag according to claim 1, characterized in that: The mass ratio of the multi-component basicity of the protective slag (CaO+2 Na2O) / (SiO2+Al2O3+B2O3) is 0.5~0.

9.

3. The high iron-copper alloy continuous casting mold protection slag according to claim 1, characterized in that: The total mass ratio of the CaO, SiO2, and Al2O3 to the total mass ratio of the B2O3 and Na2O is 0.25-1.

5.

4. The high iron-copper alloy continuous casting mold protection slag according to claim 1, characterized in that: The viscosity of the protective slag at 1200℃ is 0.1~0.7Pa.s.

5. A method for preparing high iron copper alloy continuous casting mold protection slag, characterized in that: The raw materials are weighed and mixed uniformly according to the mass percentage of each component in claim 1, and melted by heating to obtain molten slag. The molten slag is poured into water and quenched to obtain a glassy protective slag block, which is then dried and crushed to a particle size of ≤200 mesh to obtain a high iron-copper alloy continuous casting crystallizer protective slag.

6. An application of the high iron copper alloy continuous casting crystallizer protection slag as described in any one of claims 1 to 4, wherein the mass percentage of Fe in the high iron copper alloy is 5-18%, and the mass percentage of Si is 0-1%.

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