Magnesian castable containing high-carbon ferrochrome slag and preparation method thereof

Abstract

The invention belongs to the technical field of refractory materials, and discloses a high-carbon ferro-chrome slag-containing magnesian castable which comprises the following raw materials: 60-75 wt% of magnesia particles, 7-22 wt% of magnesia fine powder, 15-25 wt% of high-carbon ferro-chrome slag fine powder, 2-7 wt% of silicon oxide micro powder and an additional dispersant. The magnesia fine powder and the high-carbon ferro-chrome slag fine powder which are weighed in proportion are ground in a vibration mill for 30-60 minutes, so that the magnesia fine powder and the high-carbon ferro-chrome slag fine powder are fully homogenized in advance, and then the homogenized mixed powder is uniformly mixed with magnesia particles, silicon oxide micro powder and a dispersing agent in proportion, so that the magnesia castable containing the high-carbon ferro-chrome slag is obtained. The magnesia fine powder and the high-carbon ferro-chrome slag fine powder are subjected to co-grinding homogenization treatment, the use temperature of the prepared high-carbon ferro-chrome slag containing magnesia castable reaches 1600 DEG C or above, meanwhile, the slag corrosion resistance and the scouring resistance of the magnesia castable are improved, and resource value extraction application of the high-carbon ferro-chrome slag in the magnesia castable is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a magnesia castable containing high-carbon ferrochrome slag and a preparation method thereof. Background Art

[0002] With the rapid development of my country's economy, people's quality of life is constantly improving, and the demand for stainless steel is increasing. High-carbon ferrochrome alloy is an important raw material for smelting stainless steel. High-carbon ferrochrome alloy is obtained by high-temperature reduction smelting of chromite ore and carbon source in a submerged arc furnace. The chromite ore contains unreduced MgO and SiO. 2 、Al 2 O 3 Impurities such as chromium and chromium form high-carbon ferrochrome slag. Smelting 1 ton of high-carbon ferrochrome alloy will produce more than 1 ton of high-carbon ferrochrome slag. my country produces millions of tons of high-carbon ferrochrome slag every year. At present, these ferrochrome slags are piled up or paved with roads, and are not well utilized. Moreover, the chromium-containing slag is kept underground for a long time, which is not conducive to environmental safety. The main components of high-carbon ferrochrome slag are MgO, SiO 2 、Al 2 O 3 The main mineral phases are spinel and forsterite, with a refractoriness of about 1600℃. Due to the presence of impurities such as Fe and Ca, especially the ferrochrome alloy remaining in the high-carbon ferrochrome slag, the volume change caused by oxidation at high temperature will affect the high-temperature volume stability of the refractory material, and the Fe generated after oxidation 2 O 3 Enter into the refractory matrix and SiO 2 、Al 2 O 3 The combined action of CaO and other elements produces a large amount of liquid phase, which makes its operating temperature not exceed 1200℃, greatly reducing the high-temperature performance of refractory materials and limiting its application in refractory materials.

[0003] In order to improve the resource utilization level of high-carbon ferrochrome slag, the document "Basic Research on Performance and Resource Application of High-carbon Ferrochrome Slag" prepared porous ceramics with excellent acid and alkali resistance through process optimization such as pore making, and prepared synthetic forsterite-spinel composite materials using high-carbon ferrochrome slag, magnesia and alumina raw materials; the patent document "Chrome Slag Forsterite Refractory Material and Preparation Method" (CN1144786A) uses high-carbon ferrochrome slag and magnesia to make unfired and fired refractory products according to the brick-making process, and transforms high-carbon ferrochrome slag into high-performance refractory materials with forsterite as the main crystal phase, improving alkali resistance. The patent document "Forsterite-spinel ceramics based on high-carbon ferrochrome slag and preparation method thereof" (CN112358288A) mixes the calcined high-carbon ferrochrome slag fine powder with magnesium oxide and aluminum oxide fine powder, and presses them into a shape, and then sinters them at a high temperature to obtain forsterite-spinel ceramics based on high-carbon ferrochrome slag; these patents or documents all add magnesia or aluminum oxide to the high-carbon ferrochrome slag to further enhance the spinel or forsterite mineral phase in the high-carbon ferrochrome slag, and utilize the excellent properties of spinel or forsterite against alkaline slag to enhance or improve the performance of the material. Patent document "A method for preparing ladle castables using high-carbon ferrochrome alloy slag" (CN111848187A) uses high-alumina balls, bauxite, kyanite, silicon carbide, activated alumina powder, cement, etc. and adds 2-11wt% chromium slag powder to prepare ladle castables, thereby realizing the utilization of ferrochrome slag and reducing the manufacturing cost of ladle castables. The patent only adds 2-11wt% chromium slag powder to circumvent the adverse effects of impurities in the chromium slag powder. None of these documents discuss how to eliminate the adverse effects of the ferrochrome alloy remaining in the high-carbon ferrochrome slag on the high-temperature performance of refractory materials at high temperatures. Summary of the invention

[0004] In view of the above problems, the present invention provides a magnesium castable containing high-carbon ferrochrome slag and a preparation method thereof, which solves the problem that impurities Fe, Ca, etc. in high-carbon ferrochrome slag, especially ferrochrome alloys remaining in high-carbon ferrochrome slag, have an adverse effect on the high-temperature performance of refractory materials at high temperatures, and is used to prepare MgO-based castables to avoid Al in high-carbon ferrochrome slag. 2 O 3 、SiO 2 , Fe 2 O 3 , CaO and other components on the high temperature resistance of castables, effectively increase the application temperature of high carbon ferrochrome slag, achieve its purpose of direct use in refractory castables, and improve the resource utilization efficiency and added value of high carbon ferrochrome slag.

[0005] The technical solution adopted by the present invention: The present invention provides a magnesia castable containing high-carbon ferrochrome slag and a preparation method thereof, wherein the mass percentage of the raw materials is: 60-75 wt% of magnesia granular material with a particle size of 8-0.074 mm, 7-22 wt% of magnesia fine powder with a particle size less than 0.074 mm, 15-25 wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 2-7 wt% of silicon oxide powder, and 0.1-0.3 wt% of a dispersant accounting for the total mass of the raw materials.

[0006] The preparation method of the high-carbon ferrochrome slag castable is as follows: each component is weighed according to the mass percentage of the raw material composition, and the magnesia fine powder and the high-carbon ferrochrome slag fine powder weighed in proportion are firstly co-grinded in a vibration mill for 30 to 60 minutes to make the magnesia fine powder and the high-carbon ferrochrome slag fine powder fully homogenized in advance, and then the homogenized magnesia fine powder and high-carbon ferrochrome slag fine powder mixed powder are uniformly mixed with magnesia granular material, silicon oxide powder and dispersant in proportion to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0007] Among them, the main chemical components of high carbon ferrochrome fine powder are MgO (20~30wt%), Al 2 O 3 (28~38wt%), SiO 2 (22~28wt%), the main mineral phases are spinel and forsterite, and the bulk density is 3.1~3.2g / cm 3 The fine powder particle size of high carbon ferrochrome slag is less than 0.074mm, the dispersed residual content of high carbon ferrochrome slag is 1%~3% of ferrochrome alloy, and the metallic chromium content in the ferrochrome alloy is 10%~40%.

[0008] Among them, magnesia granules and magnesia fine powder are sintered magnesia or fused magnesia with a MgO content greater than 94wt% and a bulk density greater than 3.2g / cm 3 The particle size of magnesia sand is 8mm~0.074mm; the particle size of magnesia sand fine powder is less than 0.074mm.

[0009] The dispersant is one of sodium tripolyphosphate and sodium hexametaphosphate or a combination of the two.

[0010] In the preparation of the present invention, magnesia fine powder with a particle size of less than 0.074 mm and high carbon ferrochrome slag fine powder with a particle size of less than 0.074 mm are firstly ground in a vibration mill for 30 to 60 minutes in a ratio of (7 to 22): (15 to 25), so that the magnesia fine powder and the high carbon ferrochrome slag fine powder are fully homogenized in advance, so that the magnesia fine powder fully covers the surface of the ferrochrome alloy exposed after the high carbon ferrochrome slag fine powder is ground, and the ferrochrome alloy will quickly react with the surrounding magnesia to form (Mg, Fe)Gr after oxidation at high temperature. 2 O 4 Spinel has a refractoriness of up to 1700°C, which prevents the chromium-iron alloy from oxidizing and generating Fe2 O 3 Enter into the matrix of the castable and react with CaO and SiO 2 、Al 2 O 3 The formation of low-melting materials reduces the performance of the castable.

[0011] The present invention is applied to MgO-based castables, utilizing MgO and Al in high-carbon ferrochrome slag. 2 O 3 、SiO 2 , FeO, CaO and other components form MgO•Al 2 O 3 Spinel, 2MgO•SiO 2 Olivine, (Mg, Fe)Al 2 O 4 Spinel and CaO-containing partial periclase solid solution, the melting points of these newly generated mineral phases are all above 1700℃, which effectively avoids Al 2 O 3 、SiO 2 , FeO, CaO and other components on the high temperature performance of refractory castables, and effectively increased the direct application temperature of high carbon ferrochrome slag and the slag erosion resistance of MgO-based castables.

[0012] The beneficial effects of the present invention are as follows: the present invention directly introduces high carbon ferrochrome slag fine powder, first grinds magnesia fine powder and high carbon ferrochrome slag fine powder in a vibration mill in proportion, so that the magnesia fine powder and high carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized mixed powder is evenly mixed with other components in proportion to obtain a magnesia castable containing high carbon ferrochrome slag. The present invention grinds and homogenizes magnesia fine powder and high carbon ferrochrome slag fine powder, avoiding the adverse effect of oxidation of chromium-iron alloy in high carbon ferrochrome slag on the high temperature performance of the castable, and the use temperature of the prepared magnesia castable containing high carbon ferrochrome slag reaches above 1600°C, while improving the slag erosion and scouring resistance of the magnesia castable, and can be widely used in high temperature fields, such as steelmaking container tundish, etc., realizing the resource value-added application of high carbon ferrochrome slag in magnesia castable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the microstructural morphology of high carbon ferrochrome slag; Figure 2 This is the energy spectrum analysis diagram of ferrochrome alloy.

[0014] Note: Figure 1 The white bright spots are dispersed chromium-iron alloy. DETAILED DESCRIPTION

[0015] The embodiments of the present invention are described in detail, but they cannot be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art can make several modifications and improvements without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0016] The magnesia castable containing high carbon ferrochrome slag and the preparation method thereof are further described in detail below through specific examples.

[0017] The high carbon ferrochrome slag used in the present invention is derived from the slag produced by high temperature reduction smelting of ferrochrome, which is selected, crushed and sieved into high carbon ferrochrome slag fine powder with a particle size of less than 0.074 mm, with an apparent porosity of 3.8-4.3% and a main chemical composition of Al 2 O 3 (28-38wt%), MgO (20-30wt%), SiO 2 (22-28wt%). Figure 1-2 As shown in the figure, the microstructure morphology of high carbon ferrochrome slag and the energy spectrum analysis diagram of ferrochrome alloy are shown respectively. Figure 1 The white bright spots in the middle are dispersed ferrochrome. As can be seen from the figure, the content of metallic chromium in the ferrochrome is 38.34%. Example 1

[0018] The magnesia castable containing high-carbon ferrochrome slag and the preparation method thereof, the raw materials are composed of 70wt% of magnesia granular material with a particle size of 8-0.074mm, 7wt% of magnesia fine powder with a particle size less than 0.074mm, 20wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074mm, 3wt% of silicon oxide micropowder, and 0.1wt% of sodium tripolyphosphate dispersant accounting for the total mass of the raw materials; during the preparation, the magnesia fine powder and the high-carbon ferrochrome slag fine powder are firstly co-grinded in a vibration mill in a ratio of 7:20 for 50 minutes, so that the magnesia fine powder and the high-carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized magnesia fine powder and high-carbon ferrochrome slag fine powder mixed powder are evenly mixed with other raw materials in proportion to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0019] The castable of the present invention is mixed with 5.5wt% water and then vibrated and cast. The castable is cured for 24 hours at room temperature and then demolded. The properties of the castable are shown in the following table:

[0020] Using the static crucible method, after heat treatment at 1600℃×3h, it has excellent resistance to slag corrosion. Example 2

[0021] The magnesia castable containing high-carbon ferrochrome slag and the preparation method thereof comprise the following raw materials in percentage by weight: 75 wt% magnesia granular material with a particle size of 8-0.074 mm, 7 wt% magnesia fine powder with a particle size less than 0.074 mm, 15 wt% high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 3 wt% silicon oxide micropowder, and 0.2 wt% sodium hexametaphosphate dispersant accounting for the total weight of the raw materials. During the preparation, the magnesia fine powder and the high-carbon ferrochrome slag fine powder are firstly co-grinded in a vibration mill in a ratio of 7:15 for 60 minutes, so that the magnesia fine powder and the high-carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized magnesia fine powder and the high-carbon ferrochrome slag fine powder mixed powder are evenly mixed with other raw materials in proportion to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0022] The castable of the present invention is mixed with 5.5wt% water and then vibrated and cast. The castable is cured for 24 hours at room temperature and then demolded. The properties of the castable are shown in the following table:

[0023] Using the static crucible method, after heat treatment at 1600℃×3h, it has excellent resistance to slag corrosion. Example 3

[0024] The magnesia castable containing high-carbon ferrochrome slag and the preparation method thereof comprise the following raw materials in percentage by weight: 65 wt% of magnesia granular material with a particle size of 8-0.074 mm, 16 wt% of magnesia fine powder with a particle size less than 0.074 mm, 15 wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 4 wt% of silicon oxide fine powder, and additionally, 0.15 wt% of sodium tripolyphosphate and 0.1 wt% of sodium hexametaphosphate composite dispersant accounting for the total weight of the raw materials. During the preparation, the magnesia fine powder and the high-carbon ferrochrome slag fine powder are firstly co-grinded in a vibration mill in a ratio of 16:15 for 40 minutes, so that the magnesia fine powder and the high-carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized magnesia fine powder and high-carbon ferrochrome slag fine powder mixed powder are uniformly mixed with other raw materials in proportion, so as to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0025] The castable of the present invention is mixed with 5.3 wt% water and then vibrated and cast. The castable is cured for 24 hours at room temperature and then demolded. The properties of the castable are shown in the following table:

[0026] Using the static crucible method, after heat treatment at 1600℃×3h, it has excellent resistance to slag corrosion. Example 4

[0027] The magnesia castable containing high-carbon ferrochrome slag and the preparation method thereof comprise the following raw materials in percentage by weight: 60 wt% of magnesia granular material with a particle size of 8-0.074 mm, 22 wt% of magnesia fine powder with a particle size less than 0.074 mm, 16 wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 2 wt% of silicon oxide micropowder, and 0.12 wt% of sodium tripolyphosphate dispersant accounting for the total weight of the raw materials. During the preparation, the magnesia fine powder and the high-carbon ferrochrome slag fine powder are firstly co-grinded in a vibration mill in a ratio of 22:16 for 55 minutes, so that the magnesia fine powder and the high-carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized magnesia fine powder and the high-carbon ferrochrome slag fine powder mixed powder are uniformly mixed with other raw materials in proportion to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0028] The castable of the present invention is mixed with 6.2 wt% water and then vibrated and cast. The castable is cured for 24 hours at room temperature and then demolded. The properties of the castable are shown in the following table:

[0029] Using the static crucible method, after heat treatment at 1600℃×3h, it has excellent resistance to slag corrosion. Example 5

[0030] The magnesia castable containing high-carbon ferrochrome slag and the preparation method thereof comprise the following raw materials in percentage by weight: 61 wt% of magnesia granular material with a particle size of 8-0.074 mm, 10 wt% of magnesia fine powder with a particle size less than 0.074 mm, 25 wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 4 wt% of silicon oxide micropowder, and 0.2 wt% of sodium hexametaphosphate dispersant accounting for the total weight of the raw materials. During the preparation, the magnesia fine powder and the high-carbon ferrochrome slag fine powder are firstly co-grinded in a vibration mill in a ratio of 10:25 for 45 minutes, so that the magnesia fine powder and the high-carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized magnesia fine powder and the high-carbon ferrochrome slag fine powder mixed powder are uniformly mixed with other raw materials in proportion to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0031] The castable of the present invention is mixed with 5.7 wt% water and evenly kneaded, and then vibrated and cast. The castable is cured for 24 hours at room temperature and then demolded. The properties of the castable prepared are shown in the following table:

[0032] Using the static crucible method, after heat treatment at 1600℃×3h, it has excellent resistance to slag corrosion. Example 6

[0033] The magnesia castable containing high-carbon ferrochrome slag and the preparation method thereof comprise the following raw materials in percentage by weight: 60 wt% of magnesia granular material with a particle size of 8-0.074 mm, 8 wt% of magnesia fine powder with a particle size less than 0.074 mm, 25 wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 7 wt% of silicon oxide fine powder, and additionally 0.25 wt% of sodium tripolyphosphate and 0.05 wt% of sodium hexametaphosphate composite dispersant accounting for the total weight of the raw materials. During the preparation, the magnesia fine powder and the high-carbon ferrochrome slag fine powder are firstly co-grinded in a vibration mill in a ratio of 8:25 for 30 minutes, so that the magnesia fine powder and the high-carbon ferrochrome slag fine powder are fully homogenized in advance, and then the homogenized magnesia fine powder and high-carbon ferrochrome slag fine powder mixed powder are evenly mixed with other raw materials in proportion to obtain the magnesia castable containing high-carbon ferrochrome slag.

[0034] The castable of the present invention is mixed with 5.0wt% water and evenly kneaded, and then vibrated and cast into shape. The castable is cured for 24 hours at room temperature and then demolded. The properties of the castable prepared are shown in the following table:

[0035] Using the static crucible method, after heat treatment at 1600℃×3h, it has excellent resistance to slag corrosion.

Claims

1. A magnesium castable containing high carbon ferrochrome slag, characterized in that: The mass percentage composition of the raw materials is: 60-75 wt% of magnesia granular material with a particle size of 8-0.074 mm, 7-22 wt% of magnesia fine powder with a particle size less than 0.074 mm, 15-25 wt% of high-carbon ferrochrome slag fine powder with a particle size less than 0.074 mm, 2-7 wt% of silicon oxide powder, and 0.1-0.3 wt% of the total mass of the raw materials as a dispersant.

2. The magnesium castable containing high carbon ferrochrome slag according to claim 1, characterized in that: The main chemical components of high carbon ferrochrome fine powder are MgO, Al2O3, SiO2, the main mineral phases are spinel and forsterite, and the bulk density is 3.1~3.2g / cm 3 .

3. A magnesium castable containing high carbon ferrochrome slag according to claim 1 or 2, characterized in that: The dispersed residual content of the ferrochrome alloy in the high carbon ferrochrome slag is 1-3wt%, and the content of metallic chromium in the ferrochrome alloy is 10-40wt%.

4. The magnesium castable containing high carbon ferrochrome slag according to claim 1, characterized in that: Magnesia granules and magnesia fine powder are sintered magnesia or fused magnesia with MgO content greater than 94wt% and bulk density greater than 3.2g / cm 3 .

5. The magnesium castable containing high carbon ferrochrome slag according to claim 1, characterized in that: The dispersant is one of sodium tripolyphosphate and sodium hexametaphosphate or a combination of the two.

6. The method for preparing a magnesium castable containing high carbon ferrochrome slag according to claim 1, characterized in that: Weigh each component according to the mass percentage of the raw material composition, first grind the magnesia fine powder and high carbon ferrochrome slag fine powder weighed in proportion in a vibration mill for 30 to 60 minutes to fully homogenize the magnesia fine powder and high carbon ferrochrome slag fine powder in advance, then mix the homogenized magnesia fine powder and high carbon ferrochrome slag fine powder mixed powder with magnesia granules, silicon oxide powder and dispersant in proportion to obtain a magnesia castable containing high carbon ferrochrome slag.

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