A method for preparing high-performance ceramic matrix composites from rare earth synergistic steel smelting solid waste

Abstract

The application discloses a method for preparing high-performance ceramic matrix composites by rare earth and steel smelting solid waste, which comprises the following steps: (1) steel solid waste pretreatment; (2) raw material proportioning and mixing: proportioning raw materials according to mass fraction: 70% of pretreated solid waste powder, 5% of rare earth oxide, 15% of clay and 10% of flux; placing all the raw materials in a planetary mixer, adding a proper amount of deionized water, controlling the water content to be 15%, controlling the mixing speed to be 250-350 r / min, and mixing for 1-3 hours to obtain uniform ceramic slurry; (3) forming; and (4) rare earth sintering. The application aims to realize that the proportion of solid waste is greater than or equal to 70%, the high-temperature resistance of the ceramic material reaches 1600 DEG C, the acid and alkali corrosion resistance is 2 times higher than that of traditional ceramic, the raw material cost is reduced by 60%, and the collaborative development of solid waste resource utilization and high-end ceramic material industry is promoted.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and advanced ceramic materials technology, and in particular relates to a method for preparing high-performance ceramic matrix composite materials by co-processing rare earth with iron and steel smelting solid waste. Background Technology

[0002] The steel industry generates a large amount of smelting solid waste such as blast furnace slag and steel slag every year. Steel companies in Inner Mongolia alone generate tens of millions of tons of solid waste annually. Currently, the utilization rate of solid waste is only 60%, with most solid waste being disposed of through roadbed backfilling and open-air dumping. This not only occupies a large amount of land resources but also easily causes soil and water pollution, resulting in enormous environmental pressure. Meanwhile, the metallurgical and chemical industries have a strong demand for high-temperature and corrosion-resistant ceramic components. However, existing ceramic materials suffer from high costs, insufficient high-temperature resistance (conventional ceramics have a high-temperature resistance of ≤1400℃), and poor corrosion resistance. Imported products account for 40% of the market and are expensive.

[0003] Existing technologies have yielded numerous studies on the preparation of ceramic materials from steel smelting solid waste, but these studies suffer from two major drawbacks: firstly, the proportion of solid waste added is low (mostly ≤50%), limiting the resource utilization rate of solid waste; secondly, the ceramic materials exhibit poor performance, lacking effective modification methods and failing to meet the application requirements of high-end metallurgical and chemical industries. Rare earth oxides possess unique crystal structures that can significantly improve the density, high-temperature resistance, and corrosion resistance of ceramic materials. However, a mature technical solution has yet to be developed for achieving the synergistic effect between rare earths and steel smelting solid waste to develop high-performance ceramic matrix composites with high solid waste content. Therefore, this invention uses steel smelting solid waste as the main raw material, adds rare earth oxides for modification, and develops a method for preparing high-performance ceramic matrix composites. This method achieves high-value utilization of solid waste while simultaneously replacing imported ceramic materials, possessing significant economic, environmental, and industrial value. Summary of the Invention

[0004] To address the existing technical problems of low utilization rate of steel solid waste, high cost and insufficient performance of ceramic materials, the purpose of this invention is to provide a method for preparing high-performance ceramic matrix composite materials by co-processing rare earth with steel smelting solid waste. This method achieves a solid waste addition ratio of ≥70%, ceramic materials with high temperature resistance up to 1600℃, and acid and alkali corrosion resistance twice that of traditional ceramics, while reducing raw material costs by 60%, thus promoting the coordinated development of solid waste resource utilization and high-end ceramic materials industry.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a method for preparing high-performance ceramic matrix composite materials using rare earth elements in conjunction with solid waste from iron and steel smelting, comprising the following steps:

[0007] (1) Pretreatment of steel solid waste: Blast furnace slag and steel slag from steel enterprises are selected as raw materials and mixed evenly at a mass ratio of 1:1; the mixture is crushed to a particle size of ≤5mm using a jaw crusher, and then ground to 200 mesh fine powder using a ball mill for 3-5 hours; the fine powder is placed in a drum magnetic separator to remove iron impurities, with a magnetic separation intensity of 1.2T and three magnetic separations, and the iron content of the solid waste powder is ≤0.5%; then the fine powder after magnetic separation is placed in a dryer to dry and remove moisture, and the pretreated solid waste powder is obtained with a purity of ≥98%;

[0008] (2) Raw material proportioning and mixing: The raw materials are proportioned by mass fraction as follows: 70% pretreated solid waste powder, 5% rare earth oxides, 15% clay, and 10% flux; all raw materials are placed in a planetary mixer, an appropriate amount of deionized water is added, the moisture content is controlled at 15%, the mixing speed is 250-350 r / min, and the mixing time is 1-3 h to obtain a uniform ceramic slurry.

[0009] (3) Molding: Select the molding process according to the product type; when preparing block ceramic parts, use a hydraulic press for dry pressing (model: Y32-100, rated pressure 100t), the mold is made of Cr12MoV material, the inner wall is coated with release agent (graphite powder + machine oil, mass ratio 1:1), the molding pressure is 48-52MPa (preferably 50MPa), the holding time is 28-32s (preferably 30s), and the pressure is slowly released after holding to obtain a block green body; when preparing tubular ceramic parts, use extrusion molding. The extrusion molding process is carried out using an extruder with a screw speed of 45-55 r / min (preferably 505 r / min), a barrel temperature of 75-85℃ (preferably 80℃), and a die exit size customized according to requirements. The extrusion pressure is 28-32 MPa (preferably 30 MPa). After extrusion, the extruder is pulled at a constant speed by a traction machine to obtain a tubular green body. The green body is then placed in a drying oven and dried at 75-85℃ (preferably 80℃) for 10-15 hours (preferably 12 hours), controlling the moisture content of the green body to ≤2% to avoid cracking during sintering.

[0010] (4) Rare earth co-sintering: The dried green body is placed in a tunnel kiln for segmented sintering using a rare earth catalytic sintering process. The tunnel kiln is divided into a preheating section, a sintering section, and a cooling section, with a length ratio of 1:2:1. First stage: from room temperature to 600℃, heating rate 3℃ / min, preheating for 2h to remove organic matter and residual moisture from the green body. Second stage: from 600℃ to 1450℃, heating rate 5℃ / min, sintering for 3h, with nitrogen gas introduced for protection (flow rate 5m³ / h). Rare earth oxides play a catalytic role in this stage, promoting crystal growth and densification. An infrared thermometer (temperature control accuracy ±5℃) is built into the sintering section. Third stage: from 1450℃ to room temperature, naturally cooling to 200℃ (cooling rate 2℃ / min), then forced air cooling (wind speed 10m / s) to room temperature to obtain ceramic matrix composite green body.

[0011] Furthermore, the discharge port size of the jaw crusher is 5mm.

[0012] Furthermore, the ball mill model is MQG3200×4500, the grinding media is alumina balls with a diameter of 20mm, and the ball-to-material ratio is 3:1.

[0013] Furthermore, iron impurities are cleaned from the surface of the drum after each magnetic separation.

[0014] Furthermore, the conditions for the dryer are set as follows: drying at 120°C for 3 hours.

[0015] Furthermore, the rare earth oxide contains: 4% cerium oxide and 1% lanthanum oxide.

[0016] Furthermore, the flux is sodium carbonate + borax in a mass ratio of 2:1.

[0017] Furthermore, post-processing and performance testing are also included: the ceramic matrix composite blank is precision machined using a grinding machine to ensure dimensional accuracy; high-temperature performance is tested using a high-temperature performance tester, and acid and alkali resistance is tested using a corrosion resistance test chamber: the blank is immersed in 5% hydrochloric acid solution and 5% sodium hydroxide solution for 72 hours respectively, and the mass loss rate is tested; the mechanical strength is tested using a universal testing machine; products with a mass loss rate ≤1%, high temperature resistance ≥1600℃, and flexural strength ≥80MPa are considered qualified products. Qualified products are then cut, ground, and packaged to obtain finished products.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0019] 1. This invention uses iron and steel smelting solid waste as the main raw material, with a solid waste addition ratio of ≥70%, realizing the high-value utilization of solid waste, reducing the land occupied by solid waste landfill, reducing the land occupied by solid waste landfill by more than 100 acres per year, and achieving a 100% comprehensive utilization rate of solid waste, thus solving the environmental protection problem of solid waste treatment in the iron and steel industry.

[0020] 2. By modifying with rare earth oxides (cerium, lanthanum) and through rare earth synergistic sintering process, the performance of ceramic materials is significantly improved. The high temperature resistance reaches 1600℃, the acid and alkali corrosion resistance is twice that of traditional ceramics, and the bending strength is ≥80MPa. It can replace imported refractory materials.

[0021] 3. Raw material costs are almost zero (solid waste is self-sufficient), rare earth usage is ≤5%, the overall raw material cost is 60% lower than traditional ceramic materials, and the product price is 40% lower than imported products, giving it significant market competitiveness;

[0022] 4. The preparation process is simple and can be implemented by modifying existing ceramic production equipment, making industrialization easy; the product is suitable for the needs of metallurgical and chemical enterprises in Inner Mongolia, with rigid market demand, and can drive more than 200 new jobs in local solid waste treatment enterprises, resulting in significant economic and social benefits. Attached Figure Description

[0023] Figure 1 These are macroscopic and microscopic schematic diagrams of the prepared composite material. Detailed Implementation

[0024] A method for preparing high-performance ceramic matrix composites using rare earth elements in conjunction with solid waste from iron and steel smelting includes the following steps:

[0025] 1. Pretreatment of Steel Waste: Blast furnace slag and steel slag from steel enterprises are selected as raw materials and mixed evenly at a mass ratio of 1:1. A jaw crusher (discharge port size 5mm) is used to crush the material to a particle size ≤5mm. The mixture is then ground to 200-mesh fine powder using a ball mill (model: MQG3200×4500, grinding media: alumina balls, diameter 20mm, ball-to-material ratio 3:1) for 4 hours. The fine powder is then placed in a drum magnetic separator (speed 30r / min) to remove iron impurities. The magnetic separation intensity is 1.2T, and the separation is performed three times (after each separation, the drum surface is cleaned to remove iron impurities). The iron content of the solid waste powder is ≤0.5%. Finally, the magnetically separated fine powder is placed in a dryer and dried at 120℃ for 3 hours to remove moisture, yielding pretreated solid waste powder with a purity ≥98%.

[0026] 2. Raw material proportioning and mixing: The raw materials are proportioned by mass fraction as follows: 70% pretreated solid waste powder, 4% rare earth oxides (cerium oxide 4% + lanthanum oxide 1%), 15% clay, and 10% flux (sodium carbonate + borax, mass ratio 2:1). All raw materials are placed in a planetary mixer, an appropriate amount of deionized water is added, the moisture content is controlled at 15%, the mixing speed is 300 r / min, and the mixing time is 2 h to obtain a uniform ceramic slurry.

[0027] 3. Molding: The molding process is selected according to the product type. When preparing block ceramic parts, a hydraulic press (model: Y32-100, rated pressure 100t) is used for dry pressing. The mold is made of Cr12MoV material, and the inner wall is coated with a release agent (graphite powder + machine oil, ratio 1:1). The molding pressure is 50MPa, the holding time is 30s, and the pressure is slowly released after holding (pressure release rate 0.5MPa / s) to obtain a block green body. When preparing tubular ceramic parts, an extrusion molding machine is used for extrusion molding. The extruder screw speed is 50r / min, the barrel temperature is 80℃, and the mold exit size is customized according to requirements (inner diameter 50-200mm, wall thickness 10-20mm). The extrusion pressure is 30MPa, and after extrusion, a traction machine is used for uniform traction (speed 0.5m / min) to obtain a tubular green body. The green body is placed in a drying oven and dried at 80℃ for 12h, controlling the moisture content of the green body to ≤2% to avoid cracking during sintering.

[0028] 4. Rare Earth Co-sintering: The dried green body is placed in a tunnel kiln for segmented sintering using a rare earth catalytic sintering process. The tunnel kiln is divided into a preheating section (room temperature - 600℃), a sintering section (600-1450℃), and a cooling section (1450℃ - room temperature), with a length ratio of 1:2:1. The first stage: from room temperature to 600℃, heating rate 3℃ / min, preheating for 2 hours to remove organic matter and residual moisture from the green body. The second stage: from 600℃ to 1450℃, heating rate 5℃ / min, sintering for 3 hours, with nitrogen protection (flow rate 5m³ / h). Rare earth oxides play a catalytic role in this stage, promoting crystal growth and densification. An infrared thermometer (temperature control accuracy ±5℃) is built into the sintering section. The third stage: from 1450℃ to room temperature, naturally cooling to 200℃ (cooling rate 2℃ / min), then forced air cooling (wind speed 10m / s) to room temperature yields the ceramic matrix composite green body.

[0029] 5. Post-processing and performance testing: The ceramic matrix composite blank is precision-machined using a grinding machine to ensure dimensional accuracy; a high-temperature performance tester is used to test its high-temperature resistance, and a corrosion resistance test chamber is used to test its acid and alkali resistance (immersed in 5% hydrochloric acid solution and 5% sodium hydroxide solution for 72 hours respectively, and the mass loss rate is tested); a universal testing machine is used to test its mechanical strength; products with a mass loss rate ≤1%, high temperature resistance ≥1600℃, and flexural strength ≥80MPa are considered qualified products. Qualified products are then cut, ground, and packaged to obtain the finished product.

[0030] Example 1: Preparation of wear-resistant ceramic lining plates for metallurgical blast furnaces

[0031] 1. Pretreatment of steel solid waste: Blast furnace slag and steel slag are mixed in a 1:1 ratio, crushed to 4mm by a jaw crusher, ground to 200 mesh by a ball mill (MQG3200×4500), removed by 1.2T magnetic separation (in 3 times), and dried at 120℃ for 3 hours to obtain pretreated solid waste powder;

[0032] 2. Raw material ratio and mixing: 70% pretreated solid waste powder, 4% cerium oxide, 1% lanthanum oxide, 15% clay, 6.7% sodium carbonate, and 3.3% borax; add deionized water to control the moisture content to 15%, mix at 300 r / min for 2 h to obtain ceramic slurry;

[0033] 3. Molding: Dry pressing with a hydraulic press (Y32-100) at 50MPa pressure for 30s to obtain a block green body of 300×200×50mm; drying at 80℃ for 12h to a moisture content of 1.8%;

[0034] 4. Rare earth co-sintering: Segmented sintering in tunnel kiln, heating to 600℃ at 3℃ / min and holding for 2h, heating to 1450℃ at 5℃ / min and holding for 3h (nitrogen flow rate 5m³ / h), then naturally cooling to 200℃ and then forced air cooling.

[0035] 5. Post-processing and inspection: Precision grinding, dimensional accuracy ±0.5mm; High temperature performance test: No deformation after holding at 1600℃ for 5h; Corrosion resistance test: Immersion in 5% hydrochloric acid solution for 72h, mass loss rate 0.8%; Immersion in 5% sodium hydroxide solution for 72h, mass loss rate 0.6%; Bending strength 85MPa; Qualified product, suitable for use as blast furnace lining in metallurgy.

[0036] Example 2: Preparation of tubular ceramic components

[0037] 1. Pretreatment of steel solid waste: Same as in Example 1, but the purity of the pretreated solid waste powder is 98.5%;

[0038] 2. Raw material ratio and mixing: 70% pretreated solid waste powder, 3.5% cerium oxide, 1.5% lanthanum oxide, 15% clay, 6.7% sodium carbonate, and 3.3% borax; after mixing, a ceramic slurry is obtained.

[0039] 3. Molding: Extrusion molding machine (screw speed 50r / min, barrel temperature 80℃), tubular green body size (inner diameter 100mm, wall thickness 15mm), dried at 80℃ for 14h, moisture content 1.5%;

[0040] 4. Sintering: Same as the sintering process in Example 1;

[0041] Performance testing: High temperature resistance 1610℃, bending strength 82MPa, mass loss rate after immersion in 5% hydrochloric acid for 72 hours is 0.7%, and mass loss rate after immersion in 5% sodium hydroxide is 0.5%, which is a qualified product.

[0042] Experimental data and analysis

[0043] Table 1 Key Experimental Data Recording Table

[0044] Experiment number Solid waste addition ratio (%) Rare earth content (%) High temperature resistance (°C) Flexural strength (MPa) Mass loss rate (%) after soaking in 5% hydrochloric acid 3-1 50 3 1450 65 1.8 3-2 60 5 1550 72 1.2 3-3 (Example 1) 70 5 1600 85 0.8 3-4 80 5 1580 78 0.9 3-5 70 0 1380 52 3.5

[0045] .

[0046] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing high-performance ceramic matrix composite materials using rare earth elements in conjunction with solid waste from iron and steel smelting, characterized in that, Includes the following steps: (1) Pretreatment of steel solid waste: Blast furnace slag and steel slag from steel enterprises are selected as raw materials and mixed evenly at a mass ratio of 1:1; the mixture is crushed to a particle size of ≤5mm using a jaw crusher, and then ground to 200 mesh fine powder using a ball mill for 3-5 hours; the fine powder is placed in a drum magnetic separator to remove iron impurities, with a magnetic separation intensity of 1.2T and three magnetic separations, and the iron content of the solid waste powder is ≤0.5%; then the fine powder after magnetic separation is placed in a dryer to dry and remove moisture, and the pretreated solid waste powder is obtained with a purity of ≥98%; (2) Raw material proportioning and mixing: The raw materials are proportioned by mass fraction as follows: 70% pretreated solid waste powder, 5% rare earth oxides, 15% clay, and 10% flux; all raw materials are placed in a planetary mixer, an appropriate amount of deionized water is added, the moisture content is controlled at 15%, the mixing speed is 250-350 r / min, and the mixing time is 1-3 h to obtain a uniform ceramic slurry. (3) Molding: Select the molding process according to the product type; when preparing block ceramic parts, use a hydraulic press for dry pressing, apply a release agent to the inner wall, the molding pressure is 48-52MPa, the holding time is 28-32s, and the pressure is slowly released after holding to obtain a block green body; when preparing tubular ceramic parts, use an extrusion molding machine for extrusion molding, the extrusion screw speed is 45-55r / min, the barrel temperature is 75-85℃, the mold outlet size is customized according to the requirements, the extrusion pressure is 28-32MPa, and after extrusion, use a traction machine to pull at a uniform speed to obtain a tubular green body; place the green body in a drying oven and dry at 75-85℃ for 10-15h, control the green body moisture content ≤2% to avoid cracking during sintering; (4) Rare earth co-sintering: The dried green body is placed in a tunnel kiln for segmented sintering, using a rare earth catalytic sintering process; the tunnel kiln is divided into a preheating section in the first stage, a sintering section in the second stage, and a cooling section in the third stage, with a length ratio of 1:2:1; the first stage: from room temperature to 600℃, heating rate 3℃ / min, preheating for 2h to remove organic matter and residual moisture from the green body; the second stage: from 600℃ to 1450℃, heating rate 5℃ / min, sintering for 3h, with nitrogen gas introduced for protection, rare earth oxides play a catalytic role in this stage, promoting crystal growth and densification, and an infrared thermometer is built into the sintering section; The third stage: from 1450℃ to room temperature, then naturally cooled to 200℃, and finally forced air cooling to room temperature to obtain ceramic matrix composite material blanks.

2. The method for preparing high-performance ceramic matrix composite materials by co-processing rare earth elements with solid waste from iron and steel smelting according to claim 1, characterized in that, The discharge port size of the jaw crusher is 5mm.

3. The method for preparing high-performance ceramic matrix composite materials by co-processing rare earth elements with solid waste from iron and steel smelting according to claim 1, characterized in that, The ball mill model is MQG3200×4500, the grinding media is alumina balls with a diameter of 20mm, and the ball-to-material ratio is 3:

1.

4. The method for preparing high-performance ceramic matrix composite materials by co-processing rare earth elements with solid waste from iron and steel smelting according to claim 1, characterized in that, Clean iron impurities from the surface of the drum after each magnetic separation.

5. The method for preparing high-performance ceramic matrix composite materials by co-processing rare earth elements with solid waste from iron and steel smelting according to claim 1, characterized in that, The conditions for the dryer are set as follows: drying at 120℃ for 3 hours.

6. The method for preparing high-performance ceramic matrix composite materials by co-processing rare earth elements with solid waste from iron and steel smelting according to claim 1, characterized in that, The rare earth oxide contains: 4% cerium oxide and 1% lanthanum oxide.

7. The method for preparing high-performance ceramic matrix composite materials using rare earth elements in conjunction with solid waste from iron and steel smelting according to claim 1, characterized in that, The flux is sodium carbonate and borax in a mass ratio of 2:

1.

8. The method for preparing high-performance ceramic matrix composite materials by co-processing rare earth elements with solid waste from iron and steel smelting according to claim 1, characterized in that, The process also includes post-processing and performance testing: the ceramic matrix composite blank is precision machined using a grinding machine to ensure dimensional accuracy; a high-temperature performance tester is used to test its high-temperature resistance, and a corrosion resistance test chamber is used to test its acid and alkali resistance: the blank is immersed in 5% hydrochloric acid solution and 5% sodium hydroxide solution for 72 hours respectively to test the mass loss rate; a universal testing machine is used to test the mechanical strength; products with a mass loss rate ≤1%, high temperature resistance ≥1600℃, and flexural strength ≥80MPa are considered qualified products. Qualified products are then cut, ground, and packaged to obtain finished products.

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