Low cost composite coated magnesium based drainage and method of making same

Abstract

The application provides a low-cost composite coating magnesium drainage agent and a preparation method thereof, and belongs to the technical field of metallurgical refractory materials. The components and weight percentages of the drainage agent are as follows: 92-97% of forsterite, 2-5% of coating mixed powder and 1-3% of high-temperature binder; wherein the components and weight percentages of the coating mixed powder are as follows: 30-50% of fly ash, 30-50% of blast furnace water slag, 10-30% of limestone and 0.5-2% of carbon. The magnesium drainage agent prepared by the application has the advantages of low price, no pollution to the environment, no destruction to the metallurgical environment of the tundish, convenient use and the like, and the opening pouring effect is stable during use.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical refractory materials technology, and relates to a low-cost composite coating magnesium diverting agent and its preparation method. Background Technology

[0002] Draining agent, also known as draining sand, is a high-temperature material filled in the ladle seat bricks and upper nozzle. Before pouring molten steel into the ladle, drainage agent must be added to block the ladle's pouring area, playing a role in sealing and draining the molten steel during continuous casting. The mechanism of drainage agent lies in its three-layer structure from top to bottom. In the initial stage of molten steel pouring into the ladle, the drainage agent on the upper surface of the nozzle quickly forms a molten layer upon contact with the molten steel, hindering the penetration of the molten steel. The sintered layer, supported by the drainage agent below, can withstand the static pressure of the molten steel without being damaged; at the same time, the sintering rate of the drainage agent slows down, and the sintered layer maintains a certain thickness. However, during the initial pouring, the unsintered drainage agent at the bottom falls due to its own weight, causing the sintered layer to lose support and break under the gravity of the molten steel, thus achieving the initial pouring (…). Figure 1 ).

[0003] If the molten steel flux is over-sintered under high temperature and pressure, or if molten steel seeps into the flux, the molten steel will condense due to the decreased temperature. When the sliding gate is in the open position, the flux cannot flow out, preventing natural pouring. If the molten steel cannot flow out automatically, oxygen burning is required for drainage. This not only damages the sliding gate but also causes secondary oxidation of some of the molten steel, affecting the quality of the cast billet and posing a safety hazard to operators. The inability to pour molten steel can also lead to low tundish levels and even forced shutdowns of the continuous casting production line. Therefore, the automatic pouring of the flux is of great significance to steelmaking.

[0004] Currently, the main types of ladle casting agents used domestically and internationally include silica, chromium, zirconium, and magnesia. Silica-based agents exhibit significant volume expansion at high temperatures, leading to reduced fluidity and a low self-opening rate. Furthermore, their acidity can affect the lifespan of the tundish. Chromium-based agents have high density, high melting point, good fluidity, high refractoriness, strong resistance to molten steel penetration, and a high self-opening rate, making them the most widely used. However, these agents are relatively expensive, and the high Cr2O3 content in chromite can affect steel quality and cause environmental pollution. Zirconium-based agents have long been considered ideal ladle casting agents, but their high price limits their application. Magnesia-based agents are relatively inexpensive and commonly used in die casting processes, but their use in continuous casting processes is limited due to their low automatic opening rate.

[0005] Magnesia-based fluxing agents are alkaline, do not contaminate molten steel, and have minimal corrosive effect on the alkaline refractory lining of the tundish, thus extending the tundish's service life and stabilizing the continuous casting process. Therefore, developing high-performance magnesium-based ladle fluxing agents is of paramount importance. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a low-cost, high-self-opening, environmentally friendly, and non-disruptive magnesium-based flow guide and its preparation method.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A low-cost composite coating magnesium-based flow guide is composed of the following components by weight percentage: 92-97% magnesium olivine, 2-5% coating mixture powder, and 1-3% high-temperature binder; wherein the components and weight percentages of the coating mixture powder are 30-50% fly ash, 30-50% blast furnace slag, 10-30% limestone, and 0.5-2% carbon.

[0009] The forsterite has a particle size of 0.02–1.5 mm, an MgO weight content of ≥45%, and a SiO2 weight content of ≥40%.

[0010] The high-temperature binder is one of liquid water glass, aluminum dihydrogen phosphate, or silica sol.

[0011] The fly ash has a particle size ≤0.045mm, an Al2O3 weight content ≥35%, and a SiO2 weight content ≥50%.

[0012] The blast furnace slag has a particle size ≤0.045mm, a CaO weight content ≥35%, a SiO2 weight content ≥30%, an Al2O3 weight content ≥15%, and a MgO weight content ≥10%.

[0013] The limestone has a particle size ≤0.045mm and a CaO weight content ≥45%.

[0014] The carbon is one or two of carbon black, graphite, and coke powder, with a particle size ≤0.010mm and a C weight content ≥90%.

[0015] The preparation method of the above-mentioned low-cost composite coating magnesium diverting agent includes the following steps:

[0016] (1) Fly ash, blast furnace slag, limestone and carbon are mixed evenly according to the proportion to prepare coating mixture powder;

[0017] (2) Mix magnesium coating powder, olivine and high-temperature binder evenly according to the ratio to prepare coated magnesium particles;

[0018] (3) Dry the prepared coated magnesium particles, cool them to room temperature and pass them through a 60-mesh sieve. The qualified material on the sieve is packaged according to the unit weight specification to obtain the finished magnesium diverting agent.

[0019] The coated magnesium particles are dried at 180–220°C until the moisture content is <0.5 wt%.

[0020] The magnesium-based flow guide of this invention is mainly made of inexpensive forsterite, which has the characteristics of high melting point, low thermal conductivity, small phase transformation expansion, stable chemical properties, and strong resistance to metal oxide corrosion. The coating mixture is mainly made of industrial solid waste fly ash, blast furnace slag, and limestone, forming a CaO-Al2O3-SiO2 system of low-melting-point phases, which is conducive to the faster formation of low-melting-point, high-viscosity melt on the surface of the flow guide, preventing floating during steel loading and preventing molten steel from penetrating into the interior of the flow guide. The carbon materials in the coating can prevent the flow guide from over-sintering and also act as a lubricant for the flow guide particles. The high-temperature binder is an inorganic binder with high drying strength, while ensuring the high-temperature bonding strength between the coating and the forsterite particles.

[0021] The beneficial effects of adopting the above technical solution are as follows: the composite magnesium flow guide prepared by the present invention has uniform and stable particle size, and has the characteristics of low price, no environmental pollution, no damage to the tundish metallurgical environment, and convenient use. During use, the casting effect is stable. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the application scenario of the drainage agent in this invention;

[0023] The markings in the diagram are: 1. Sliding nozzle, 2. Draining agent, 3. Sintered layer, 4. Molten layer, 5. Bedding brick. Detailed Implementation

[0024] Example 1

[0025] A method for preparing a low-cost composite coated magnesium-based drainage agent includes the following steps:

[0026] (1) Mix the following substances evenly according to the ratio to prepare a coating mixture powder for later use;

[0027]

[0028] (2) Mix the following substances evenly according to the ratio to prepare coated magnesium particles;

[0029]

[0030] (3) Dry the prepared coated magnesium particles at 200℃ until the moisture content is <0.5%;

[0031] (4) After the dried and qualified coated magnesium particles are cooled to room temperature, they are passed through a 60-mesh sieve. The qualified material on the sieve is packaged according to the single weight specification to become the finished magnesium diverting agent.

[0032] Magnesium-based diverting agent produced according to this scheme was used in a steel plant's ordinary steel ladle, achieving a self-opening rate of over 98%.

[0033] Example 2

[0034] A method for preparing a low-cost composite coated magnesium-based drainage agent includes the following steps:

[0035] (1) Mix the following substances evenly according to the ratio to prepare a coating mixture powder for later use;

[0036]

[0037] (2) Mix the following substances evenly according to the ratio to prepare coated magnesium particles;

[0038]

[0039] (3) Dry the prepared coated magnesium particles at 220℃ until the moisture content is <0.5%;

[0040] (4) After the dried and qualified coated magnesium particles are cooled to room temperature, they are passed through a 60-mesh sieve. The qualified material on the sieve is packaged according to the single weight specification to become the finished magnesium diverting agent.

[0041] Magnesium-based diverting agent produced according to this scheme was used in the LF refining ladle of a steel plant, achieving a self-opening rate of over 97%.

[0042] Example 3

[0043] A method for preparing a low-cost composite coated magnesium-based drainage agent includes the following steps:

[0044] (1) Mix the following substances evenly according to the ratio to prepare a coating mixture powder for later use;

[0045]

[0046] (2) Mix the following substances evenly according to the ratio to prepare coated magnesium particles;

[0047]

[0048] (3) Dry the prepared coated magnesium particles at 180℃ until the moisture content is <0.5%;

[0049] (4) After the dried and qualified coated magnesium particles are cooled to room temperature, they are passed through a 60-mesh sieve. The qualified material on the sieve is packaged according to the single weight specification to become the finished magnesium diverting agent.

[0050] Magnesium-based diverting agent produced according to this scheme was used in the RH refining ladle of a steel plant, achieving a self-opening rate of over 98%.

[0051] Example 4

[0052] A method for preparing a low-cost composite coated magnesium-based drainage agent includes the following steps:

[0053] (1) Mix the following substances evenly according to the ratio to prepare a coating mixture powder for later use;

[0054]

[0055] (2) Mix the following substances evenly according to the ratio to prepare coated magnesium particles;

[0056]

[0057] (3) Dry the prepared coated magnesium particles at 200℃ until the moisture content is <0.5%;

[0058] (4) After the dried and qualified coated magnesium particles are cooled to room temperature, they are passed through a 60-mesh sieve. The qualified material on the sieve is packaged according to the single weight specification to become the finished magnesium diverting agent.

[0059] Magnesium-based diverting agent produced according to this scheme was used in a steel plant's ordinary steel ladle, achieving a self-opening rate of over 99%.

[0060] Example 5

[0061] A method for preparing a low-cost composite coated magnesium-based drainage agent includes the following steps:

[0062] (1) Mix the following substances evenly according to the ratio to prepare a coating mixture powder for later use;

[0063]

[0064] (2) Mix the following substances evenly according to the ratio to prepare coated magnesium particles;

[0065]

[0066] (3) Dry the prepared coated magnesium particles at 180℃ until the moisture content is <0.5%;

[0067] (4) After the dried and qualified coated magnesium particles are cooled to room temperature, they are passed through a 60-mesh sieve. The qualified material on the sieve is packaged according to the single weight specification to become the finished magnesium diverting agent.

[0068] Magnesium-based diverting agent produced according to this scheme was used in the LF+RH refining ladle of a steel plant, achieving a self-opening rate of over 99%.

Claims

1. A low-cost composite-coated magnesium-based drainage agent, characterized in that, It is composed of the following components by weight percentage: 92-97% magnesium olivine, 2-5% coating mixture powder, and 1-3% high-temperature binder; wherein, the components and weight percentages of the coating mixture powder are: 30-50% fly ash, 30-50% blast furnace slag, 10-30% limestone, and 0.5-2% carbon. The fly ash has a particle size ≤0.045mm, an Al2O3 weight content ≥35%, and a SiO2 weight content ≥50%. The blast furnace slag has a particle size ≤0.045mm, a CaO weight content ≥35%, a SiO2 weight content ≥30%, an Al2O3 weight content ≥15%, and a MgO weight content ≥10%.

2. The low-cost composite coating magnesium diverting agent according to claim 1, characterized in that, The forsterite has a particle size of 0.02–1.5 mm, an MgO weight content of ≥45%, and a SiO2 weight content of ≥40%.

3. The low-cost composite coating magnesium diverting agent according to claim 1, characterized in that, The high-temperature binder is one of liquid water glass, aluminum dihydrogen phosphate, or silica sol.

4. The low-cost composite coating magnesium diverting agent according to claim 1, characterized in that, The limestone has a particle size ≤0.045mm and a CaO weight content ≥45%.

5. The low-cost composite coating magnesium diverting agent according to claim 1, characterized in that, The carbon is one or two of carbon black, graphite, and coke powder, with a particle size ≤0.010mm and a C weight content ≥90%.

6. A method for preparing a low-cost composite coating magnesium-based drainage agent according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Fly ash, blast furnace slag, limestone and carbon are mixed evenly according to the proportion to prepare coating mixture powder; (2) Mix magnesium coating powder, olivine and high-temperature binder evenly according to the ratio to prepare coated magnesium particles; (3) Dry the prepared coated magnesium particles, cool them to room temperature and pass them through a 60-mesh sieve. The qualified material on the sieve is packaged according to the unit weight specification to obtain the finished magnesium diverting agent.

7. The method for preparing the low-cost composite coating magnesium diverting agent according to claim 6, characterized in that, The coated magnesium particles are dried at 180–220°C until the moisture content is <0.5 wt%.

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