Pre-melting casting powder base material, preparation method and application of pre-melting casting powder base material in continuous casting casting powder

Abstract

The invention provides a premelting type casting powder base material, a preparation method and application of the premelting type casting powder base material in continuous casting casting powder, and relates to the technical field of casting powder, the base material is composed of quartz powder and calcite, and the mass ratio of the quartz powder to the calcite is (2-3): (3-2). The special steel casting powder is stable and relatively single in component, low in impurity content and more stable in component after pre-melting, and when the special steel casting powder is prepared, addition of other unnecessary alkalinity adjusting materials is reduced, the formula complexity is reduced, it is guaranteed that the casting powder separate melting phenomenon cannot occur in the special steel casting process, and the smooth process of the special steel continuous casting process and the surface quality of a casting blank are guaranteed; and the development requirements of times are met. The technical problems that in the prior art, in order to reduce the binary alkalinity of the casting powder, a high-silicon-oxide-content raw material is added into a casting powder base material, so that balling is not prone to occurring in the production process, hollow particles are formed, the casting powder is poor in particle size and strength, and spreadability and the slagging effect are affected in the using process are solved.

Description

Technical Field

[0001] This invention relates to the field of protective slag technology, and in particular to a pre-melted protective slag base material, its preparation method, and its application in continuous casting protective slag. Background Technology

[0002] In the past, quartz powder or calcite powder were used in protective slags, but only as materials to adjust the binary basicity of the slag, and the dosage was relatively low, with both materials rarely used simultaneously. In recent years, cost reduction has become a top priority for steel companies, and competition in the continuous casting protective slag market has become increasingly fierce. In addition, steel companies are increasingly turning to special steel casting to improve their survival. To meet the casting requirements of some special steels, a suitable protective slag is needed, such as for high-alumina steel or high-grade silicon steel. These steels require the protective slag to have good lubrication properties and be resistant to deformation during use. This requires the protective slag to have a low binary basicity (0.4-0.70). However, adjusting the base material of the conventional protective slag requires adding a large amount of materials with high silica content, such as glass powder, to reduce the binary basicity of the product. If the amount of such materials is too large, it will be difficult to form balls during production, resulting in hollow granules with poor particle size and strength. This will affect the spreadability and slag formation effect during use, thus affecting lubrication and heat transfer. At the same time, a large amount of glass powder will also easily cause bubbles to be generated in the protective slag during melting, affecting the normal melting of the protective slag and making it difficult to meet the normal casting requirements of this type of steel.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] One of the objectives of this invention is to provide a pre-melted protective slag base material to solve the technical problem in the prior art where, in order to reduce the binary basicity of the protective slag, a high silica content raw material is added to the protective slag base material, which leads to difficulty in spheroidization during production, resulting in hollow particles, poor particle size and strength of the protective slag, and affecting the spreadability and slag-forming effect during use.

[0005] The second objective of this invention is to provide a method for preparing the aforementioned base material.

[0006] A third objective of this invention is to provide the application of the above-mentioned base material or the base material prepared by the above-mentioned preparation method in continuous casting protective slag.

[0007] The fourth objective of this invention is to provide a continuous casting protective slag.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a pre-melted protective slag base material, the base material being composed of quartz powder and calcite, wherein the mass ratio of quartz powder to calcite is 2~3:3~2.

[0009] Furthermore, the base material comprises the following chemical components by mass percentage: 44%~59% SiO2, ≤1% MgO, 20%~30% CaO, ≤0.5% Fe2O3 and ≤0.5% Al2O3, with the balance being unavoidable impurities and volatiles.

[0010] Furthermore, the binary basicity of the base material is 0.35~0.7.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned base material, comprising melting quartz powder and calcite according to the formula amount, spraying water to cool and form crushed material, and grinding and sieving to obtain the base material.

[0012] Furthermore, the melting temperature is 1250~1350℃.

[0013] Furthermore, the sieving includes a 300-mesh screen with a passing rate of ≥90%.

[0014] Thirdly, the present invention provides the application of the above-mentioned base material or the base material prepared by the above-mentioned preparation method in continuous casting protective slag.

[0015] Furthermore, the continuous casting protective slag includes high-alumina steel continuous casting protective slag and / or high-grade silicon steel continuous casting protective slag.

[0016] Fourthly, the present invention provides a continuous casting protective slag, wherein the continuous casting protective slag comprises the above-mentioned base material or a base material prepared by the above-mentioned preparation method.

[0017] Furthermore, the base material accounts for 40% to 60% of the total mass of the continuous casting protective slag.

[0018] This invention provides a pre-melted protective slag base material with stable and relatively simple composition and low impurity content. In particular, the composition is further stabilized after pre-melting with a specific ratio, and volatile matter is removed. Using this pre-melted base material in the preparation of protective slags for special steels reduces the addition of unnecessary basicity-adjusting materials, lowers formula complexity, ensures that protective slag segregation does not occur during the special steel casting process, and guarantees smooth process operation and billet surface quality, meeting the needs of modern development. It solves the technical problem in existing technologies where high-silica-content raw materials are added to the protective slag base material to reduce binary basicity, leading to difficulty in pelletizing during production, the formation of hollow particles, poor particle size and strength of the protective slag, and affecting spreadability and slag formation during use. Detailed Implementation

[0019] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0020] Unless otherwise stated, the methods and techniques of the present invention are generally carried out according to conventional methods well known in the art and as described in various general and more specific references, which are cited and discussed throughout this specification.

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The present invention provides a pre-melted protective slag base material, which is composed of quartz powder and calcite, wherein the mass ratio of quartz powder to calcite is 2~3:3~2.

[0023] Quartz powder and calcite are both natural minerals with stable and relatively simple compositions and low impurity content. Their composition is further stabilized after pre-melting in a specific ratio, and volatile matter is removed. Using them as pre-melted base materials reduces the need for other unnecessary basicity-adjusting materials when formulating special steel protective slag, lowers formula complexity, ensures no protective slag segregation during special steel casting, and guarantees smooth process operation and billet surface quality, meeting the needs of modern development. This method solves the technical problem in existing technologies where high silica content raw materials are added to the protective slag base material to reduce binary basicity, leading to difficulty in pelletizing during production, forming hollow particles, resulting in poor particle size and strength of the protective slag, and affecting spreadability and slag formation during use.

[0024] The mass ratio of quartz powder to calcite can be, but is not limited to, 2:3, 2.3:3, 2.5:3, 2.8:3, 1:1, 3:2.3, 3:2.5, 3:2.8 or 3:2, or any ratio between 2 and 3:3.

[0025] In some specific embodiments, the base material comprises the following chemical components by mass percentage: 44%~59% SiO2, ≤1% MgO, 20%~30% CaO, ≤0.5% Fe2O3 and ≤0.5% Al2O3, with the balance being unavoidable impurities and volatiles.

[0026] The mass percentage of SiO2 can be, but is not limited to, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, or 59%, or any value between 44% and 59%.

[0027] The mass percentage of MgO can be, but is not limited to, 0.1%, 0.2%, 0.4%, 0.6%, 0.8% or 0.1%, or any percentage ≤1%.

[0028] The mass percentage of CaO can be, but is not limited to, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, or any value between 20% and 30%.

[0029] The mass percentage of Fe2O3 can be, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, or any percentage ≤0.5%.

[0030] The mass percentage of Al2O3 can be, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, or any percentage ≤0.5%.

[0031] By adjusting the mass ratio of quartz to calcite to 2-3:3-2, the binary basicity of the final base material is precisely controlled. In some specific embodiments, the binary basicity of the base material is 0.35-0.7.

[0032] According to another aspect of the present invention, a method for preparing the above-mentioned base material is also provided, comprising melting quartz powder and calcite according to the formula amount, spraying water to cool and form crushed material, and grinding and sieving to obtain the base material.

[0033] Impurities are removed and composition is stabilized through melting, and volatile gases are effectively discharged. After removing volatiles, the base material has a denser structure and a more stable chemical composition; the risk of bubble formation during continuous casting is reduced, and "slag bursting" or "splashing" of the protective slag in the crystallizer is avoided; the batch consistency and reliability of the subsequent protective slag products are improved; water spray cooling promotes glass formation, increases the activity of the base material, facilitates uniform melting in the protective slag, improves slag formation speed and spreadability, and ensures the rapid formation of a continuous liquid slag layer in the crystallizer.

[0034] In some specific embodiments, the melting temperature is 1250~1350℃. In some specific embodiments, the sieving includes a 300-mesh screen with a passing rate of ≥90%.

[0035] The protective slag prepared from the above-mentioned base material can inhibit slag degradation caused by Al2O3 enrichment; maintain a stable liquid slag layer thickness and ensure good lubrication; have low slag consumption and high utilization rate; and have no adhesion, no steel leakage alarm, no surface scars or cracks, which can significantly improve the quality of the cast billet.

[0036] According to another aspect of the present invention, the application of the above-described base material or the base material prepared by the above-described preparation method in continuous casting protective slag is also provided.

[0037] In some specific embodiments, the continuous casting protective slag includes high-alumina steel continuous casting protective slag and / or high-grade silicon steel continuous casting protective slag.

[0038] The continuous casting speed is 0.9~1.5m / min.

[0039] According to another aspect of the present invention, a continuous casting protective slag is also provided, the continuous casting protective slag comprising the above-described base material or a base material prepared by the above-described preparation method.

[0040] In some specific embodiments, the base material accounts for 40% to 60% of the total mass of the continuous casting protective slag. The specific base material percentage can be, but is not limited to, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, or 60%, or any value between 40% and 60%.

[0041] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0042] raw material: Calcite: The core component is CaCO3, with a CaO content of ≥53.5%.

[0043] Quartz powder: The core component is SiO2, with a SiO2 content of ≥95%.

[0044] Example 1 The pre-melted protective slag base material is composed of quartz powder and calcite in a mass percentage ratio of 60:40.

[0045] The pre-melted protective slag base material is prepared according to the following steps: S1: Weigh the qualified quartz powder and calcite according to the weight percentage, dry mix them for 15 minutes, and then put them into an electric arc furnace and heat them at 1300±50℃ to melt them. S2: Open the discharge port of the electric arc furnace, pour the completely molten liquid into the set container, and spray water to cool the molten base material flowing into the container. The cooled base material becomes fragments. S3: Feed the crushed base material into a Raymond mill and grind it until the passing rate of a 300-mesh sieve is ≥90%, thus obtaining the base material.

[0046] The chemical composition (wt%) of the pre-melted protective slag base material is as follows: SiO2: 58.5%, MgO: 0.28%, CaO: 21.85%, Fe2O3: 0.48%, Al2O3: 0.3%, and <0.5% trace impurities; the remainder is volatile CO2. The binary basicity of the pre-melted protective slag base material is 0.37.

[0047] application: This material is used in the protective slag of continuous casting of high-manganese and high-alumina steel in a steel plant. The base material accounts for 45% by weight. Compared with the previous scheme, which used a portion of slag, pre-melted material, and clinker, and had a large proportion of glass powder, the total number of raw materials in the formula is reduced by 3, namely slag, pre-melted material and clinker. This can reduce the tendency of segregation caused by the large number of materials during use, and at the same time reduce the material cost by 285 yuan / ton.

[0048] The cross-section of the casting production section is 230*1215mm. 2 Casting speed 1.1m / min. Usage: The protective slag reacted well on the surface of the crystallizer during use, and there was no segregation during the melting process. The overall melting was uniform, the three-layer structure was obvious, the liquid slag layer was 9-11mm, the slag consumption was 0.45kg / t, and no alarm or adhesion occurred during the process. The surface of the produced billet was free of scabs.

[0049] Example 2 The pre-melted protective slag base material is composed of quartz powder and calcite in a mass percentage ratio of 55:45.

[0050] The pre-melted protective slag base material is prepared according to the following steps: S1: Weigh the qualified quartz powder and calcite according to the weight percentage, dry mix them for 15 minutes, and then put them into an electric arc furnace and heat them at 1300±50℃ to melt them. S2: Open the discharge port of the electric arc furnace, pour the completely molten liquid into the set container, and spray water to cool the molten base material flowing into the container. The cooled base material becomes fragments. S3: Feed the crushed base material into a Raymond mill and grind it until the passing rate of a 300-mesh sieve is ≥90%, thus obtaining the base material.

[0051] The chemical composition (wt%) of the pre-melted protective slag base material is as follows: SiO2: 53.6%, MgO: 0.31%, CaO: 24.58%, Fe2O3: 0.44%, Al2O3: 0.31%, and <0.5% trace impurities; the remainder is volatile CO2. The binary basicity of the pre-melted protective slag base material is 0.46.

[0052] application: This pre-melted material is used in the protective slag of continuous casting of 38CrMoAl steel in a steel plant. The weight percentage of this pre-melted material is 55%. Compared with the previous scheme, which used wollastonite as the base material and had a large amount of glass powder and clinker, the total number of raw materials in the formula is reduced by two, namely wollastonite and clinker. In addition, the proportion of glass powder is also significantly reduced. This can reduce the tendency of segregation caused by the large number of materials during use, and at the same time reduce the material cost by 347 yuan / ton.

[0053] The casting production section is 300*340mm. 2 Casting speed 1.3m / min. Usage: The protective slag reacts well on the surface of the crystallizer during use. The slag strips are generated slowly and are small, making them easy to pick out. There is no deformation of the protective slag, which could lead to sticking or steel leakage accidents. The liquid slag layer is 8~12mm, and the slag consumption is 0.32kg / t. There is no scabbing on the surface of the produced billet.

[0054] Example 3 The pre-melted protective slag base material is composed of quartz powder and calcite in a 50:50 mass percentage ratio.

[0055] The pre-melted protective slag base material is prepared according to the following steps: S1: Weigh the qualified quartz powder and calcite according to the weight percentage, dry mix them for 15 minutes, and then put them into an electric arc furnace and heat them at 1300±50℃ to melt them. S2: Open the discharge port of the electric arc furnace, pour the completely molten liquid into the set container, and spray water to cool the molten base material flowing into the container. The cooled base material becomes fragments. S3: Feed the crushed base material into a Raymond mill and grind it until the passing rate of a 300-mesh sieve is ≥90%, thus obtaining the base material.

[0056] The chemical composition (wt%) of the pre-melted protective slag base material is as follows: SiO2: 48.8%, MgO: 0.34%, CaO: 27.3%, Fe2O3: 0.41%, Al2O3: 0.31%, and <0.5% trace impurities; the remainder is volatile CO2. The binary basicity of the pre-melted protective slag base material is 0.56.

[0057] Application 1: This pre-melted material is used in the protective slag of continuous casting of B50A310 steel in a steel plant. The weight percentage of the pre-melted material is 42%. Compared with the previous scheme, which used phosphorus slag as the base material and calcite and glass powder as materials to adjust the alkalinity, the total number of raw materials in the formula is reduced by two, namely phosphorus slag and calcite. This can reduce the tendency of segregation caused by the large number of materials during use, and at the same time reduce the material cost by 265 yuan / ton.

[0058] The casting production section is 230*1450mm. 2 Casting speed 1.5 m / min. Usage: During use, the protective slag spread well on the liquid surface of the crystallizer, with small slag strips and a liquid-slag layer thickness of 10-12 mm. The heat flux density curve was relatively stable, and no steel leakage alarm occurred. The billet surface was smooth, the vibration mark depth was appropriate, and no defects such as slag pits, longitudinal cracks, or transverse cracks were observed.

[0059] Application 2: This pre-melted material is used in the protective slag of continuous casting of B50A310 steel in a steel plant. The weight percentage of the pre-melted material is 49%. Compared with the previous scheme, which used slag and wollastonite as the base material and calcite, glass powder and clinker as materials to adjust the basicity, the total number of raw materials in the formula is reduced by 4, namely two base materials, calcite and clinker. This can significantly reduce the tendency of segregation caused by the large number of materials during use, and at the same time reduce the material cost by 310 yuan / ton.

[0060] The casting production section is 230*1830mm. 2 Casting speed 0.9m / min. Usage: The protective slag spreads well in the crystallizer, the heat flow curve is balanced, the thermal image shows no abnormalities, no alarms occur, the liquid surface in the entire crystallizer is active, the protective slag melts evenly, the three-layer structure is obvious, and no edge cracks appear on the surface of the cast billet.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pre-melted mold flux base material characterized by comprising: The base material is composed of quartz powder and calcite, and the mass ratio of the quartz powder and the calcite is 2-3:3-2.

2. The base stock of claim 1 wherein, The base material comprises the following chemical components in mass percentage: 44%-59% of SiO2, ≤1% of MgO, 20%-30% of CaO, ≤0.5% of Fe2O3 and ≤0.5% of Al2O3, and the balance is inevitable impurities and volatile matter.

3. The binder of claim 1 or 2, characterized in that The binary basicity of the base material is 0.35-0.

7.

4. Process for the preparation of the base material according to any one of claims 1 to 3, characterized in that, The base material is prepared by melting quartz powder and calcite according to the formula, water quenching to form fragments, and grinding and sieving.

5. The production method according to claim 4, characterized by, The melting temperature is 1250-1350 ℃.

6. The preparation method according to claim 4, characterized in that, The sieving comprises a 300-mesh screen with a passing rate of ≥90%.

7. Use of the base material of any one of claims 1-3 or the base material prepared by the preparation method of any one of claims 4-6 in continuous casting protective slag.

8. Use according to claim 7, characterized in that, The continuous casting protective slag comprises high-aluminum steel continuous casting protective slag and / or high-grade silicon steel continuous casting protective slag.

9. A continuous casting protective slag, characterized by, The continuous casting protective slag comprises the base material of any one of claims 1-3 or the base material prepared by the preparation method of any one of claims 4-6.

10. The continuous casting protective slag according to claim 9, characterized in that, The base material accounts for 40%-60% of the total mass of the continuous casting protective slag.