Tundish carbon-free dry material based on inorganic salt complex binding agent

Abstract

This invention relates to the field of refractory materials for continuous casting, and discloses a carbon-free dry tundish based on an inorganic salt composite binder. The dry tundish consists of aggregate, powder, binder, and additives. By total weight, the binder includes: 1.0-5.5 wt% sodium metasilicate containing water of crystallization, 0.5-2.5 wt% aluminum dihydrogen phosphate, and 0.1-0.8 wt% mineralizer. The aggregate is fused magnesia or sintered magnesia, with a particle size distribution of 15-25% 5-3 mm, 20-30% 3-1 mm, and 15-25% 1-0 mm. The powder is fine fused magnesia powder with a particle size not exceeding 0.088 mm, comprising 20-35% of the powder. Under the catalytic action of the mineralizer, the composite binder undergoes dehydration and condensation to form multinuclear nanoclusters with Al-O-P as bridging bonds. These nanoclusters cross-link to form a three-dimensional network structure, providing early strength at low temperatures. When the temperature rises above 800℃, it transforms into an aluminum-phosphate ceramic phase to achieve high-temperature strength. This invention has the advantages of being completely carbon-free, having excellent strength properties, high baking efficiency, good impermeability, and being environmentally friendly and safe.

Description

Technical Field

[0001] This invention relates to the field of refractory materials for continuous casting, and more specifically, to carbon-free dry tundish materials based on inorganic salt composite binders. Background Technology

[0002] The tundish is a crucial functional vessel in the continuous casting process, and its working lining performance directly affects the quality of molten steel and the efficiency of continuous casting. Dry billet systems are widely used due to their advantages such as convenient construction, low energy consumption, and long service life. Traditional dry billet systems often use phenolic resin as a binder. However, resin binders introduce carbon elements, and during baking and use, carbon oxidation can lead to the following problems: phenolic resin binders emit harmful gases such as formaldehyde and cresol at high temperatures, polluting the environment and endangering human health; they form pores, reducing the density and strength of the material; carbon oxidation leaves structural weaknesses, affecting service life; and it increases the carbon content of the molten steel, which is detrimental to the smelting of high-quality steel grades such as clean steel and ultra-low carbon steel.

[0003] Developed countries began researching inorganic-bonded dry refractory materials as early as the beginning of the 21st century. Japan's Kurosaki-Harima Refractories Co., Ltd. developed a silicate-based carbon-free dry refractory material, while Europe primarily researched phosphate-bonded systems. In recent years, leading international companies have begun to focus on inorganic salt composite systems, using multiple inorganic salts to address the performance deficiencies of single binders. Domestic refractory material companies such as Beijing Lier and Ruitai Technology have developed various carbon-free dry refractory materials. Henan Gengsheng Refractory Materials Co., Ltd.'s phosphate-borosilicate glass composite binder system solved the resin binder contamination problem, but suffers from high raw material costs and insufficient low-temperature strength. Ma'anshan Lier Co., Ltd.'s magnesium sulfate heptahydrate-sulfamic acid system, while low-cost, is hygroscopic and has poor stability. In existing technologies, sulfates and sulfamic acid salts are hygroscopic, and modified solid resins still contain small amounts of volatile organic compounds. Therefore, developing a novel composite bonding system capable of achieving high-strength bonding throughout the entire temperature range, while being completely carbon-free, has become a key technical challenge in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a carbon-free dry feedstock based on an inorganic salt composite binder, comprising aggregate, powder, binder, and additives. The binder is an inorganic salt composite binder, and based on the total weight of the dry feedstock, the inorganic salt composite binder comprises: 1.0-5.5 wt% sodium metasilicate containing water of crystallization, 0.5-2.5 wt% aluminum dihydrogen phosphate, and 0.1-0.8 wt% mineralizer. The aggregate is fused magnesia or sintered magnesia, with a particle size distribution of 15-25% for 5-3mm, 20-30% for 3-1mm, and 15-25% for 1-0mm. The powder is fused magnesia fine powder with a particle size of no more than 0.088 mm and a content of 20-35%. The mineralizing agent is a fluoride; During the heating process, the inorganic salt composite binder forms multinuclear nanoclusters with Al-OP as the bridging bond through dehydration and condensation reaction under the catalysis of the mineralizer. The multinuclear nanoclusters cross-link to form a three-dimensional network structure to provide early strength at low temperature. When the temperature rises to above 800°C, the three-dimensional network structure acts as a precursor to generate an aluminum-phosphate ceramic phase to achieve high-temperature strength.

[0005] Preferably, the content of the sodium metasilicate containing water of crystallization is 4.0-5.0 wt%.

[0006] Preferably, the content of aluminum dihydrogen phosphate is 1.0-2.0 wt%.

[0007] Preferably, the content of the mineralizing agent is 0.3-0.6 wt%.

[0008] Preferably, the aggregate comprises both fused magnesia and sintered magnesia.

[0009] Preferably, the mineralizing agent includes at least one of aluminum fluoride or spodumene.

[0010] Preferably, the content of the fused magnesia fine powder is 25-32%.

[0011] Preferably, the aggregate has the following particle size distribution: 5-3mm accounts for 18-22%, 3-1mm accounts for 23-27%, and 1-0mm accounts for 18-22%.

[0012] Preferably, the aluminum-phosphate ceramic phase is AlPO4 or an AlPO4 solid solution.

[0013] A method for preparing carbon-free dry intermediate packing material based on inorganic salt composite binder includes the following steps: Mix aggregates and powders of all grades for 1-3 minutes; Add the inorganic salt composite binder and additives, and continue mixing for 5-15 minutes until homogeneous; The product is obtained through packaging.

[0014] The beneficial effects of this invention are as follows: 1. Completely carbon-free: Eliminates the risk of steel contamination from carbon materials, suitable for all steel grades, especially high-quality steel.

[0015] 2. Excellent strength performance: Based on the new mechanism of forming a low-temperature ceramic phase by a multi-core nanocluster cross-linked network, the material has high strength throughout the entire process from baking to use, without any mid-temperature strength trough, and has excellent erosion and spalling resistance.

[0016] 3. High baking efficiency: Due to the high reactivity of the binder system and the rapid formation of the nano-network, the baking time of the intermediate bread can be significantly shortened, and the operating rate can be improved.

[0017] 4. Excellent impermeability: The formed ceramic bonding phase is dense, which can effectively inhibit the penetration and erosion of molten slag and extend the service life of the tundish.

[0018] 5. Environmentally friendly and safe: No toxic substances such as asphalt and phenols are emitted, making production and use environmentally friendly. Detailed Implementation

[0019] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples. Example 1

[0020] This embodiment proposes a carbon-free dry intermediate packing material based on an inorganic salt composite binder, which consists of aggregate, powder, binder, and additives. The binder is an inorganic salt composite binder, and its composition, based on the total weight of the dry packing material, includes: 2.5 wt% sodium metasilicate containing water of crystallization, 1.5 wt% aluminum dihydrogen phosphate, and 0.5 wt% mineralizer. The aggregate is fused magnesia, with a particle size distribution of 20% 4mm, 25% 2mm, and 20% 0.5mm. The powder is fused magnesia fine powder with a particle size of no more than 0.088 mm, and its content is 30%. The mineralizing agent is a fluoride; During the heating process, the inorganic salt composite binder forms multinuclear nanoclusters with Al-OP as the bridging bond through dehydration and condensation reaction under the catalysis of the mineralizer. The multinuclear nanoclusters cross-link to form a three-dimensional network structure to provide early strength at low temperature. When the temperature rises to above 800°C, the three-dimensional network structure acts as a precursor to generate an aluminum-phosphate ceramic phase to achieve high-temperature strength.

[0021] in: The content of sodium metasilicate containing water of crystallization is 4.5 wt%.

[0022] The content of aluminum dihydrogen phosphate is 1.5 wt%.

[0023] The content of mineralizer is 0.45 wt%.

[0024] The aggregate includes both fused magnesia and sintered magnesia.

[0025] Mineralizing agents include aluminum fluoride.

[0026] The content of fused magnesia fine powder is 28%.

[0027] The aggregate size distribution is: 20% 4mm, 25% 2mm, and 20% 0.5mm.

[0028] The aluminum-phosphate ceramic phase is AlPO4. Example 2

[0029] The difference between this embodiment and Embodiment 1 is that: Based on the total weight of the dry materials, the inorganic salt composite binder comprises: 1.0 wt% sodium metasilicate containing crystal water, 0.5 wt% aluminum dihydrogen phosphate, and 0.1 wt% mineralizer; The aggregate is sintered magnesia, with a particle size distribution of 15% 5mm, 20% 3mm, and 15% 1mm. The powder is fused magnesia fine powder with a particle size of no more than 0.088 mm, and its content is 20%. The content of sodium metasilicate containing water of crystallization is 4.0 wt%.

[0030] The content of aluminum dihydrogen phosphate is 1.0 wt%.

[0031] The content of mineralizer is 0.3 wt%.

[0032] Mineralizing agents include spodumene.

[0033] The content of fused magnesia fine powder is 25%.

[0034] The aluminum-phosphate ceramic phase is an AlPO4 solid solution. Example 3

[0035] The difference between this embodiment and Embodiment 1 is that: Based on the total weight of the dry materials, the inorganic salt composite binder comprises: 5.5 wt% sodium metasilicate containing crystal water, 2.5 wt% aluminum dihydrogen phosphate, and 0.8 wt% mineralizer; The aggregate is fused magnesia or sintered magnesia, with a particle size distribution of 25% 3mm, 30% 1mm, and 25% 0.1mm. The powder is fused magnesia fine powder with a particle size of no more than 0.088 mm, and its content is 35%. The content of sodium metasilicate containing water of crystallization is 5.0 wt%.

[0036] The content of aluminum dihydrogen phosphate is 2.0 wt%.

[0037] The content of mineralizer is 0.6 wt%.

[0038] Mineralizing agents include aluminum fluoride or spodumene.

[0039] The content of fused magnesia fine powder is 32%. Example 4

[0040] This embodiment proposes a method for preparing carbon-free dry intermediate packing material based on inorganic salt composite binder, including the following steps: Mix aggregates and powders of all grades for 1-3 minutes; Add the inorganic salt composite binder and additives, and continue mixing for 5-15 minutes until homogeneous; The product is obtained through packaging.

[0041] Example 1: A carbon-free dry feed for intermediate treasuries has the following composition: (1) Electrofused magnesia aggregate (5-3mm: 20%, 3-1mm: 25%, 1-0mm: 20%) 65% (2) Fine fused magnesia powder (≤0.088mm) 28% (3) Composite binder: containing 4.5% sodium metasilicate with water of crystallization, 1.5% aluminum dihydrogen phosphate, and 0.4% aluminum fluoride. Preparation process: Pour the aggregate and powder into a mixer and dry mix for 2 minutes; pour the composite binder containing water of crystallization sodium metasilicate, aluminum dihydrogen phosphate, and aluminum fluoride into a small tank and mix for 1 minute; add the composite binder into the mixer and mix for 10 minutes, then package after discharge.

[0042] Test results:

[0043] Example 2: (1) Aggregate: 5-3mm fused magnesia particles: 18%, 3-1mm porous sintered magnesia: 25%, 1-0mm lightweight magnesium aluminum spinel: 28%.

[0044] (2) Fine powder: ≤0.088mm fused magnesia fine powder: 15%, active magnesium oxide micro powder: 4%, sintering accelerator is 325 mesh ZrO22% + 325 mesh TiO22%.

[0045] (3) Binder system (3%): Sodium metasilicate containing water of crystallization: 4.8%, aluminum dihydrogen phosphate: 1.0%, mineralizer composite package: aluminum fluoride 0.1% + spodumene 0.1%.

[0046] Preparation process: Pour the aggregate and powder into a mixing mill and dry mix for 2 minutes; pour the composite binder containing water of crystallization sodium metasilicate, aluminum dihydrogen phosphate, and mineralizer into a small material tank and mix for 1 minute; add the composite binder into the mixing mill and mix for 10 minutes, then package after discharge.

[0047] Test results:

[0048] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A tundish carbon-free dry material based on a composite inorganic salt binder, consisting of aggregates, powders, a binder and additives, characterized in that, The binder is an inorganic salt composite binder, and based on the total weight of the dry material, the inorganic salt composite binder comprises: 1.0-5.5 wt% sodium metasilicate containing crystal water, 0.5-2.5 wt% aluminum dihydrogen phosphate, and 0.1-0.8 wt% mineralizer; The aggregate is fused magnesia or sintered magnesia, with a particle size distribution of 15-25% for 5-3mm, 20-30% for 3-1mm, and 15-25% for 1-0mm. The powder is fused magnesia fine powder with a particle size of no more than 0.088 mm and a content of 20-35%. The mineralizing agent is a fluoride; During the heating process, the inorganic salt composite binder forms multinuclear nanoclusters with Al-OP as the bridging bond through dehydration and condensation reaction under the catalysis of the mineralizer. The multinuclear nanoclusters cross-link to form a three-dimensional network structure to provide early strength at low temperature. When the temperature rises to above 800°C, the three-dimensional network structure acts as a precursor to generate an aluminum-phosphate ceramic phase to achieve high-temperature strength.

2. The intermediate bulk carbon-free dry material according to claim 1, characterized in that, The content of the sodium metasilicate containing crystal water is 4.0-5.0 wt%.

3. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The content of aluminum dihydrogen phosphate is 1.0-2.0 wt%.

4. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The content of the mineralizer is 0.3-0.6 wt%.

5. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The aggregate contains both fused magnesia and sintered magnesia.

6. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The mineralizing agent includes at least one of aluminum fluoride or spodumene.

7. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The content of the fused magnesia fine powder is 25-32%.

8. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The aggregate particle size distribution is as follows: 5-3mm accounts for 18-22%, 3-1mm accounts for 23-27%, and 1-0mm accounts for 18-22%.

9. The carbon-free dry feed for intermediate tundishes according to claim 1, characterized in that, The aluminum-phosphate ceramic phase is AlPO4 or an AlPO4 solid solution.

10. The method for preparing the carbon-free dry intermediate batch material according to any one of claims 1-9, characterized in that, Includes the following steps: Mix aggregates and powders of all grades for 1-3 minutes; Add the inorganic salt composite binder and additives, and continue mixing for 5-15 minutes until homogeneous; The product is obtained through packaging.

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