Low-carbon refractory material additive, preparation method and low-carbon refractory material

Abstract

The embodiment of the invention discloses a low-carbon refractory material additive. The additive is a magnesium oxide and silicon magnesium nitride composite material; the magnesium oxide and silicon magnesium nitride composite material is prepared from metal magnesium, silicon dioxide, ammonium chloride and nitrogen; the preparation method comprises the following steps: mixing metal magnesium, silicon dioxide and ammonium chloride into an original mixture; the raw material mixture is subjected to a combustion synthesis reaction in a nitrogen atmosphere, the magnesium oxide and silicon magnesium nitride composite material is obtained, and in the composite material, magnesium oxide grains are partially wrapped by silicon magnesium nitride. As a low-carbon refractory material additive, the magnesium oxide and magnesium silicon nitride composite material can improve the thermal shock resistance and slag resistance of the low-carbon MgO-C refractory material.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a low-carbon refractory material additive, a preparation method and a low-carbon refractory material. Background Art

[0002] MgO-C refractory materials have good mechanical properties, excellent slag resistance and good thermal shock resistance, and are cost-effective. They are currently widely used in the lining, sliding nozzle and ladle slag line of oxygen top-blown converters, electric furnaces and refining furnaces. In traditional MgO-C refractory systems, the carbon content is generally 10-20wt%. The high carbon content leads to the following problems: (1) At high temperatures, carbon is easily oxidized to form CO / CO2, forming pores, reducing the strength and slag erosion resistance of magnesium carbon bricks; (2) Too high carbon content will cause carbonization of molten steel, which is not conducive to clean steel production; (3) The high thermal conductivity of carbon will increase the heat loss of molten steel, increase the tapping temperature, and aggravate material erosion; (4) It consumes a large amount of non-renewable graphite resources, which is not conducive to the sustainable development of resources, and increases CO2 and CO emissions.

[0003] Magnesium-carbon refractory materials with low carbon content are one of the future development trends; however, as the carbon content in MgO-C refractory materials decreases, its thermal conductivity will decrease, its thermal shock resistance will decrease, its slag erosion resistance will weaken, and its elastic modulus will increase; therefore, it is necessary to develop low-carbon MgO-C refractory materials with excellent thermal shock stability and slag corrosion resistance. Summary of the invention

[0004] In view of this, some embodiments disclose a low-carbon refractory additive, wherein the additive is a composite material of magnesium oxide and magnesium silicon nitride.

[0005] Furthermore, some embodiments disclose a low-carbon refractory additive, which is prepared from metal magnesium, silicon dioxide, ammonium chloride and nitrogen; the preparation method includes:

[0006] Metal magnesium, silicon dioxide and ammonium chloride are mixed to form a raw material mixture;

[0007] The raw material mixture undergoes a combustion synthesis reaction in a nitrogen atmosphere to obtain a composite material of magnesium oxide and magnesium silicon nitride. In the composite material, a portion of magnesium oxide grains is wrapped by magnesium silicon nitride.

[0008] In the low-carbon refractory additive disclosed in some embodiments, in the raw material mixture, the mass fraction of metallic magnesium powder is 34-45%, the mass fraction of silicon dioxide is 28-38%, and the mass fraction of ammonium chloride is 17-38%; the pressure of the nitrogen atmosphere is 0.5-2.0 MPa.

[0009] In some embodiments of the low-carbon refractory additive disclosed, the raw material mixture is placed in a graphite crucible for combustion synthesis reaction.

[0010] On the other hand, some embodiments disclose a low-carbon refractory material, wherein the low-carbon refractory material comprises a composite material of magnesium oxide and magnesium silicon nitride; wherein the mass content of the composite material of magnesium oxide and magnesium silicon nitride is 1-7%.

[0011] The low-carbon refractory material additive disclosed in the embodiment of the present invention is a composite material of magnesium oxide and magnesium silicon nitride. The composite material is prepared by combustion synthesis reaction of metallic magnesium, silicon dioxide and ammonium chloride in a nitrogen atmosphere. The obtained magnesium oxide and magnesium silicon nitride composite material is used as a low-carbon refractory material additive to improve the thermal shock stability and slag resistance of the low-carbon MgO-C refractory material. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Example 1 product powder XRD curve diagram;

[0013] Figure 2 SEM image of the powder of the product of Example 1;

[0014] Figure 3 Example 2 product powder XRD curve diagram;

[0015] Figure 4 Example 2 product powder SEM image;

[0016] Figure 5 Example 3 product powder XRD curve diagram;

[0017] Figure 6 SEM image of the product powder of Example 3. DETAILED DESCRIPTION

[0018] The word "embodiment" used herein as an "exemplary" does not necessarily mean that any embodiment described is superior or better than other embodiments. Performance index tests in the embodiments of the present invention are performed using conventional test methods in the art unless otherwise specified. It should be understood that the terms described in the embodiments of the present invention are only used to describe specific implementation methods and are not intended to limit the contents disclosed in the embodiments of the present invention.

[0019] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by ordinary technicians in the technical field to which the embodiments of the present invention belong; other experimental methods and technical means not specifically specified in the embodiments of the present invention refer to experimental methods and technical means commonly used by ordinary technicians in the field.

[0020] The terms "substantially" and "approximately" used herein are used to describe small fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. The numerical data represented or presented in the range format herein are used only for convenience and brevity, and should therefore be flexibly interpreted as including not only the values ​​clearly listed as the limits of the range, but also all independent values ​​or sub-ranges contained in the range. For example, the numerical range of "1-5%" should be interpreted as including not only the clearly listed values ​​of 1% to 5%, but also the independent values ​​and sub-ranges within the range shown. Therefore, independent values ​​such as 2%, 3.5% and 4% and sub-ranges such as 1%-3%, 2%-4% and 3%-5% are included in this numerical range. This principle also applies to the range of only one numerical value. In addition, such an interpretation applies regardless of the width of the range or the characteristics described.

[0021] In this document, including in the claims, transitional words such as "comprises," "includes," "with," "having," "containing," "involving," "accommodating," etc. are understood to be open-ended, i.e., meaning "including but not limited to." Only the transitional words "consisting of" and "composed of" are closed transitional words.

[0022] In order to better illustrate the present invention, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the gist of the present invention.

[0023] Under the premise of no conflict, the technical features disclosed in the embodiments of the present invention may be arbitrarily combined, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present invention.

[0024] Some embodiments disclose low-carbon refractory additives, the additives are composite materials of magnesium oxide and magnesium silicon nitride. Magnesium silicon nitride is a ceramic material formed by magnesium, silicon and nitrogen elements, and its chemical formula is usually expressed as MgSiN2. This material combines the excellent properties of silicon nitride Si3N4 and magnesium oxide MgO, and has high hardness, high wear resistance, high heat resistance and good thermal shock resistance. The hardness value of magnesium silicon nitride is close to that of silicon nitride, usually between 15 and 20GPa, and it has excellent wear resistance due to its strong covalent bond, and is particularly suitable for use in high wear environments; under high temperature conditions, magnesium silicon nitride exhibits good stability and can maintain its performance unchanged in the high temperature range of 1000 to 1200°C; magnesium silicon nitride has excellent thermal shock resistance and can maintain its structural integrity in an environment with rapid temperature fluctuations; in terms of chemical properties, magnesium silicon nitride exhibits good oxidation resistance at high temperatures and can effectively resist oxidation reactions. At the same time, it also has a certain corrosion resistance to acids and alkalis, and can maintain its stable performance in corrosive environments.

[0025] Since magnesium silicon nitride has excellent properties such as high fracture toughness, high strength, high hardness, good high-temperature oxidation resistance and thermal conductivity, magnesium silicon nitride as an additive can improve the comprehensive performance of low-carbon refractory materials.

[0026] Some embodiments disclose a low-carbon refractory material additive, which is prepared from metal magnesium, silicon dioxide, ammonium chloride and nitrogen; the preparation method includes:

[0027] Metal magnesium, silicon dioxide and ammonium chloride are mixed to form a raw material mixture;

[0028] The raw material mixture undergoes a combustion synthesis reaction in a nitrogen atmosphere to obtain a composite material of magnesium oxide and magnesium silicon nitride. In the composite material, a portion of magnesium oxide grains is wrapped by magnesium silicon nitride.

[0029] Usually, MgO / MgSiN2 composite powder is prepared by combustion synthesis method in nitrogen atmosphere with metallic magnesium powder, silicon dioxide and ammonium chloride as raw materials. The preparation process is efficient, simple, economical and fast. Using MgO / MgSiN2 composite powder as an additive and adding it to low-carbon magnesium-carbon refractory materials can significantly enhance the thermal shock resistance of low-carbon magnesium-carbon refractory materials through multiple mechanisms such as improving the toughness of the material, optimizing thermal conductivity, building a tight microstructure, and promoting crack deflection and bridging. At the same time, the slag erosion resistance of low-carbon magnesium-carbon refractory materials is greatly improved by improving the chemical stability of the material, forming a dense protective layer, reducing porosity and enhancing material strength. These comprehensive performance improvements enable low-carbon magnesium-carbon refractory materials to exhibit better stability and longer service life under high temperature and complex working conditions.

[0030] In some embodiments, the mass fraction of the metallic magnesium powder in the raw material mixture is 34-45%, the mass fraction of silicon dioxide is 28-38%, and the mass fraction of ammonium chloride is 17-38%; the pressure of the nitrogen atmosphere is 0.5-2.0 MPa.

[0031] In some embodiments of the low-carbon refractory additive disclosed, the raw material mixture is placed in a graphite crucible for a combustion synthesis reaction.

[0032] Some embodiments disclose a low-carbon refractory material, wherein the low-carbon refractory material comprises a composite material of magnesium oxide and magnesium silicon nitride; wherein the mass content of the composite material of magnesium oxide and magnesium silicon nitride is 1-7%.

[0033] Some embodiments disclose a low-carbon refractory material, which is a magnesium-carbon refractory material. A composite material of magnesium oxide and magnesium silicon nitride is used as an additive, mixed with the raw materials for preparing the magnesium-carbon refractory material, and reacted under set conditions to obtain a low-carbon refractory material containing the composite material of magnesium oxide and magnesium silicon nitride.

[0034] Some embodiments disclose low-carbon refractory materials, wherein raw materials for preparing the magnesium-carbon refractory materials include fused magnesia, graphite, metallic silicon, boron carbide, and phenolic resin.

[0035] The technical details are further illustrated below in conjunction with embodiments.

[0036] Example 1

[0037] In Example 1, the preparation method of the low-carbon refractory additive comprises:

[0038] Mix 45.35% magnesium powder, 37.80% silicon dioxide and 16.85% ammonium chloride for 40 minutes;

[0039] Mix well and fill in The sample was placed in a cylindrical graphite crucible and put into a combustion synthesis reactor so that it was in contact with the tungsten wire. The reactor door was closed, and nitrogen was passed through after vacuuming to make the pressure in the furnace reach 0.75MPa. The power was turned on so that the heat generated by the tungsten wire ignited the sample. The heat released by the reaction ignited the reaction system, and the combustion wave spread from top to bottom to obtain the product powder.

[0040] The prepared product powder was subjected to X-ray diffraction analysis and SEM combined with EDS analysis. The results are as follows: Figure 1 , Figure 2 As shown; Figure 1 The XRD results show that the main phases in the product powder prepared in Example 1 are MgSiN2 and MgO; Figure 2The SEM image shows magnesium oxide grains and irregular flaky substances attached to their surface. Combined with energy spectrum analysis, it is determined that they are MgO and MgSiN2 respectively. The comprehensive results show that the product powder contains MgO grains and MgSiN2, and the MgO grains are partially wrapped by MgSiN2.

[0041] Example 2

[0042] In Example 2, the preparation method of the low-carbon refractory additive is carried out with reference to Example 1, wherein the mass fractions of the metal magnesium powder, silicon dioxide and ammonium chloride are 38.81%, 32.35% and 28.84% respectively.

[0043] The prepared product powder was subjected to X-ray diffraction analysis and SEM combined with EDS analysis. The results are as follows: Figure 3 , Figure 4 As shown; Figure 3 The XRD results show that the main phases in the product powder prepared in Example 1 are MgSiN2 and MgO; Figure 4 The SEM image shows magnesium oxide grains and irregular flaky substances attached to their surface. Combined with energy spectrum analysis, it is determined that they are MgO and MgSiN2 respectively. The comprehensive results show that the product powder contains MgO grains and MgSiN2, and the MgO grains are partially wrapped by MgSiN2.

[0044] Example 3

[0045] In Example 3, the preparation method of the low-carbon refractory additive is carried out with reference to Example 1, wherein the mass fractions of the metal magnesium powder, silicon dioxide and ammonium chloride are 33.92%, 28.27% and 37.81% respectively.

[0046] The prepared product powder was subjected to X-ray diffraction analysis and SEM combined with EDS analysis. The results are as follows: Figure 5 , Figure 6 As shown; Figure 5 The XRD results show that the main phases in the product powder prepared in Example 1 are MgSiN2 and MgO; Figure 6 The SEM image shows magnesium oxide grains and irregular flaky substances attached to their surface. Combined with energy spectrum analysis, it is determined that they are MgO and MgSiN2 respectively. The comprehensive results show that the product powder contains MgO grains and MgSiN2, and the MgO grains are partially wrapped by MgSiN2.

[0047] Example 4

[0048] The magnesium oxide / magnesium silicon nitride composite powder material obtained in Example 2 was used as an additive, and was mixed with the raw materials of the low-carbon magnesium-carbon refractory material, pressed into shape, and then cross-linked at 240°C to prepare a magnesium-carbon refractory low-carbon aluminum-carbon brick sample.

[0049] As a comparative example, there is no additive in the raw materials of the low-carbon magnesium-carbon refractory material. The raw materials are batched, mixed, pressed and then cross-linked at 240°C to form a magnesium-carbon refractory low-carbon aluminum-carbon brick sample.

[0050] The Archimedes drainage method was used to test the volume density and apparent porosity of the low carbon aluminum carbon brick samples. The universal testing machine was used to test the flexural strength and compressive strength of the carbon aluminum carbon brick samples. The static crucible test method was used to test the corrosion resistance of the carbon aluminum carbon brick samples by sintering at 1600°C in a high temperature electric furnace and keeping warm for 3 hours. The thermal shock resistance of the carbon aluminum carbon brick samples was characterized according to the residual strength retention rate after sintering at 1100°C in a high temperature box-type resistance furnace and keeping warm for 3 hours and performing rapid cooling and heating treatments three times.

[0051] Table 1 lists the raw material composition of magnesium-carbon refractory materials and the proportion of each component to additives. In Table 1, M0 is a comparative sample without MgO / MgSiN2 composite powder, and M1, M3, M5, and M7 are low-carbon magnesium-carbon refractory samples obtained with additive contents of 1%, 3%, 5%, and 7%, respectively. In Table 1, each raw material composition is measured by mass content. Table 2 lists the performance parameters of different low-carbon magnesium-carbon refractory materials.

[0052] According to the test results, when the addition amount of MgO / MgSiN2 composite powder is 5wt%, the M7 sample has the highest apparent porosity and the lowest volume density; the compressive strength of this sample first increases and then decreases with the increase of the addition amount of MgO / MgSiN2 composite powder, and the compressive strength of the M5 sample is the largest; the flexural strength first increases and then decreases with the increase of the addition amount of MgO / MgSiN2 composite powder, and the M5 sample has the largest flexural strength.

[0053] With the increase of the addition amount of MgO / MgSiN2 composite powder, the compressive strength first increases and then decreases. When the addition amount of MgO / MgSiN2 composite powder is 5wt%, the residual strength retention rate of low-carbon magnesium-carbon refractory after thermal shock is the highest, which is 86.2%, which is 18.8% higher than that of the blank sample. With the increase of the addition amount of MgO / MgSiN2 composite powder, the compressive strength gradually increases. Compared with the M0 sample, the oxide layer thickness and oxidation index of the M7 sample are reduced by 54.6% and 56.9% respectively. The sample has the best oxidation resistance. In addition, the addition of MgO / MgSiN2 composite powder significantly improves the slag erosion resistance of the refractory. With the increase of the addition amount of MgO / MgSiN2 composite powder, the compressive strength first increases and then decreases. The erosion index of the M5 sample is the lowest, which is 9.94%.

[0054] Table 1 Low carbon magnesium carbon refractory material composition

[0055]

[0056]

[0057] Table 2 Performance parameters

[0058]

[0059] The low-carbon refractory material additive disclosed in the embodiment of the present invention is a composite material of magnesium oxide and magnesium silicon nitride. The composite material is prepared by combustion synthesis reaction of metallic magnesium, silicon dioxide and ammonium chloride in a nitrogen atmosphere. The obtained magnesium oxide and magnesium silicon nitride composite material is used as a low-carbon refractory material additive to improve the thermal shock stability and slag resistance of the low-carbon MgO-C refractory material.

[0060] The technical solutions disclosed in the embodiments of the present invention and the technical details disclosed in the embodiments are merely illustrative of the inventive concept of the present invention and do not constitute a limitation on the technical solutions of the embodiments of the present invention. Any conventional changes, replacements or combinations of the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.

Claims

1. Low carbon refractory additive, characterized in that: The additive is a composite material of magnesium oxide and magnesium silicon nitride.

2. The low-carbon refractory additive according to claim 1, characterized in that: The additive is prepared from magnesium metal, silicon dioxide, ammonium chloride and nitrogen; the preparation method comprises: Metal magnesium, silicon dioxide and ammonium chloride are mixed to form a raw material mixture; The raw material mixture undergoes a combustion synthesis reaction in a nitrogen atmosphere to obtain a composite material of magnesium oxide and magnesium silicon nitride, in which a portion of magnesium oxide grains is wrapped by magnesium silicon nitride.

3. The low-carbon refractory additive according to claim 2, characterized in that: In the raw material mixture, the mass fraction of metal magnesium powder is 34-45%, the mass fraction of silicon dioxide is 28-38%, and the mass fraction of ammonium chloride is 17-38%; the pressure of the nitrogen atmosphere is 0.5-2.0Mpa.

4. The low-carbon refractory additive according to claim 2, characterized in that: The raw material mixture is placed in a graphite crucible for combustion synthesis reaction.

5. Low carbon refractory material, characterized in that: The low-carbon refractory material comprises the magnesium oxide and magnesium silicon nitride composite material according to any one of claims 1 to 4; wherein the mass content of the magnesium oxide and magnesium silicon nitride composite material is 1 to 7%.

6. The low carbon refractory material according to claim 5, characterized in that: The low-carbon refractory material is a magnesium-carbon refractory material, which is prepared by mixing magnesium oxide and magnesium silicon nitride composite materials as additives with raw materials for preparing the magnesium-carbon refractory material and reacting under set conditions to obtain a low-carbon refractory material containing magnesium oxide and magnesium silicon nitride composite materials.

7. The low carbon refractory material according to claim 6, characterized in that: The raw materials for preparing the magnesium-carbon refractory material include fused magnesia, graphite, metallic silicon, boron carbide and phenolic resin.

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