Method for preparing basalt fiber from coal gasification slag

Abstract

The invention discloses a method for preparing basalt fibers from coal gasification slag, and belongs to the field of inorganic non-metallic materials. The method comprises the following steps: crushing the coal gasification coarse slag; the crushed coal gasification coarse slag is heated to be molten, then heat preservation is conducted, and a homogenized oxide melt is obtained; and carrying out melt spinning on the melt to prepare the basalt fiber. Based on the composition and physical property characteristics of the coal gasification slag, on the basis of proper raw materials, the basalt fiber is prepared by adjusting the composition of the raw materials and homogenizing the raw materials. According to the invention, the coal gasification slag which is a solid waste with low resource utilization degree is converted into a high-value fiber material, and the characteristics of high SiO2 and Al2O3 content and high vitrification degree of the coal gasification slag are fully utilized.

Description

Technical Field

[0001] This invention belongs to the field of inorganic non-metallic materials, and specifically relates to a method for preparing basalt fibers from coal gasification slag. Background Technology

[0002] Basalt fiber is a type of glassy fiber material with multiple components. It is usually formed into continuous fibers from basalt ore through melt spinning and is a high-tech fiber material. Due to its high strength, good corrosion resistance and heat resistance, basalt fiber has been widely used in building structural reinforcement, resin composites, heat-resistant insulation materials and marine engineering.

[0003] Although basalt ore resources are widely distributed, basalt with uniform composition and suitable melting properties for melt spinning is extremely limited, which seriously restricts the development of the basalt fiber industry. Therefore, it is necessary to expand the raw material sources of basalt fiber.

[0004] In the coal gasification process, minerals in the coal are oxidized at high temperatures in the gasifier to form oxide melts. These oxide melts are then quenched with water to form glassy coal gasification slag, which is then discharged. The coal gasification process places certain requirements on the melting point, viscosity, and crystallization characteristics of the slag, requirements that are quite similar to those for oxide melts in the basalt spinning process. The final coal gasification slag is a glassy waste residue of multiple oxides discharged from the coal gasification process, and its composition, melting, and viscosity characteristics are also similar to those of spun basalt. Therefore, using coal gasification slag to prepare basalt fibers becomes a possibility.

[0005] Compared to typical basalt ore, coal gasification slag generally has a SiO2 / Al2O3 ratio below 2.5, exhibiting strong crystallization ability and unique spinning characteristics, thus requiring further limitations on its composition and operating procedures. Therefore, there is an urgent need to find suitable coal gasification slag for melt spinning and a method to directly melt and homogenize it to obtain a coal gasification slag melt, which can then be spun into basalt fibers. In view of this, this application is hereby submitted. Summary of the Invention

[0006] This invention aims to provide a method for preparing basalt fiber from coal gasification slag. Based on the composition and physical properties of coal gasification slag, and using suitable raw materials, basalt fiber is obtained by adjusting the raw material composition and homogenization. This invention transforms coal gasification slag, a solid waste with low resource utilization, into a high-value fiber material, fully utilizing its high SiO2 and Al2O3 content and high glass transition degree. Coal gasification slag includes coarse slag and fine slag. The coarse slag is discharged in a molten state from the bottom of the gasifier and forms granular residue after water quenching. Its particles are relatively large, dense, and have a relatively low carbon content. The fine slag consists of small particles carried out from the top of the gasifier with syngas and captured in the subsequent washing and dust removal system. Its particles are fine, flocculent, loosely structured, and have well-developed pores. The unburned carbon content is usually much higher than that of the coarse slag.

[0007] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing basalt fibers from coal gasification slag, comprising the following steps: S1: Crush the coarse slag from coal gasification; S2: The crushed coal gasification slag is heated to melt, and then kept at the temperature to obtain a homogenized oxide melt; S3: The melt is melt-spun into basalt fibers.

[0008] In some preferred embodiments, in step S1, the composition of the coal gasification coarse slag satisfies: Al2O3 ≤ 30 wt.%, SiO2 / Al2O3 ≥ 1.65, and Fe2O3 ≤ 15 wt.%. Al2O3 and Fe2O3 are typical easily crystallizing components. The Al2O3 and Fe2O3 contents of coal gasification coarse slag are generally higher than those of natural basalt, therefore, it is necessary to select coal gasification coarse slag with lower contents.

[0009] In some preferred embodiments, in step S1, the particle size of the coal gasification coarse slag after crushing is below 100 mesh, such as 150 mesh, 200 mesh, or any particle size below 100 mesh.

[0010] In some preferred embodiments, in step S2, before heating the crushed coarse coal gasification slag to the melting temperature, fine coal gasification slag is added at a temperature between 550-800°C. This achieves four effects: firstly, it fully utilizes the coal gasification slag; secondly, it aids in heating; and thirdly, it enhances the homogenization effect by utilizing the reducing effect of carbonaceous matter, further improving the quality of the prepared basalt fiber.

[0011] Furthermore, the mass ratio of the fine coal gasification slag to the coarse coal gasification slag is (0.2-1):100.

[0012] Furthermore, the particle size of the coal gasification fine slag is below 100 mesh, such as 150 mesh, 200 mesh, or any particle size below 100 mesh.

[0013] Further, in step S2, the temperature for heating to the melting point is 1450-1650°C. The melting device can be an intermittent resistance furnace, a crucible furnace, or a continuous melting furnace.

[0014] In some preferred embodiments, the heat preservation time in step S2 is 6-12 hours.

[0015] In some alternative embodiments, in step S3, the melt spinning apparatus includes one of a platinum crucible, a platinum substitute crucible, a tank furnace, a high-speed centrifugal spinning machine, or a high-speed blower.

[0016] In some preferred embodiments, in step S3, the temperature of the melt spinning is 1300-1450°C.

[0017] In some alternative embodiments, in step S3, the basalt fiber comprises continuous fiber filaments or fixed-length fiber filaments.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses coal gasification slag with suitable composition for spinning directly for the preparation of basalt fiber without the need for other additives. The operation is simple and easy to implement. (2) Based on the composition and physical properties of coal gasification slag, the present invention melts and spins it into basalt fiber. This method not only enriches the raw material source of basalt fiber, but also provides a new way for the large-scale, high-value and material utilization of coal gasification slag. Attached Figure Description

[0019] Figure 1 Photographs and electron microscope images of the fiber samples prepared in Example 1 of the present invention (top left); Figure 2 Photographs and electron microscope images of the fiber samples prepared for Example 5 of the present invention (top left). Detailed Implementation

[0020] The terminology used in the implementation section of this application is for the purpose of explaining specific embodiments of this application only, and is not intended to limit this application.

[0021] The fiber strength testing methods in the examples and comparative examples are based on the monofilament tensile method in GB / T 23265-2023 "Chopted Basalt Fibers for Cement Concrete and Mortar". The fiber samples were first dried at 50°C, and then stretched using a fiber tensile tester at a clamping distance of 5 mm and a tensile speed of 1 mm / min until fracture. The tensile strength of a single fiber was calculated using the recorded maximum load, and the average value of the effective samples was taken as the final result.

[0022] Example 1: A method for preparing basalt fibers from coal gasification slag: (1) Select the coarse coal gasification slag from the aerospace gasification furnace of Taiyuan Chemical Industry Group. Its composition characteristics are: Al2O3=19.21wt.%, SiO2 / Al2O3=2.67, Fe2O3=11.7 wt.%, and crush it into slag powder below 100 mesh; (2) The slag powder in (1) is heated and melted in an electric resistance furnace at a rate of 5℃ / min to 1550℃, and kept at the temperature for 8 hours for homogenization treatment to obtain homogenized gasified slag melt. (3) Using a platinum crucible, spinning was performed at 1320 °C and a speed of 1000 m / min to spin the homogenized gasified slag melt from (2) into continuous fiber filaments with a diameter of 20.1 μm. Fiber samples and microscopic photographs are shown below. Figure 1 As shown. Its strength is 1380 MPa without the application of a wetting agent.

[0023] Example 2: A method for preparing basalt fibers from coal gasification slag: (1) Select the coarse coal gasification slag from Shell gasifier of Lu'an Chemical Group. Its composition characteristics are: Al2O3=28.61wt.%, SiO2 / Al2O3=1.72, Fe2O3=8.1wt.%, and crush it into slag powder below 100 mesh; (2) The slag powder in (1) is heated and melted in an electric resistance furnace at a rate of 5℃ / min to 1600℃, and kept at the temperature for 12 h for homogenization treatment to obtain homogenized gasified slag melt; (3) Using a platinum crucible, the homogenized gasified slag melt from (2) was spun into continuous fiber filaments with a diameter of 15.5 μm at 1380 °C and a speed of 1400 m / min. The strength was 1403 MPa without the application of a wetting agent.

[0024] Example 3: A method for preparing basalt fibers from coal gasification slag: (1) The coarse coal gasification slag from the aerospace gasification furnace of Ningxia Baofeng Energy Group was selected. Its composition characteristics were: Al2O3=19.84wt.%, SiO2 / Al2O3=2.51, Fe2O3=13.96wt.%, and it was crushed into slag powder below 100 mesh. (2) The slag powder in (1) is heated and melted in an electric resistance furnace at a rate of 5℃ / min to 1450℃, and kept at the temperature for 10 h for homogenization treatment to obtain homogenized gasified slag melt. (3) The homogenized gasified slag melt from (2) was spun into continuous fibers with a diameter of 24.5 μm at 1350 °C and a speed of 900 m / min using a platinum crucible. The strength was 1343 MPa without the application of a wetting agent.

[0025] Example 4: A method for preparing basalt fibers from coal gasification slag: (1) Select the coarse coal gasification slag from the aerospace gasification furnace of Taiyuan Chemical Industry Group. Its composition characteristics are: Al2O3=19.21wt.%, SiO2 / Al2O3=2.67, Fe2O3=11.7 wt.%, and crush it into slag powder below 100 mesh; (2) The slag powder in (1) is heated in an electric resistance furnace at a rate of 5℃ / min. When the temperature reaches 550-600℃, the fine coal gasification slag of the gasifier is added (the mass ratio of fine coal gasification slag to coarse coal gasification slag is 0.5:100). Then, the temperature is continued to be heated to 1550℃ to melt, and the mixture is kept warm and homogenized for 8 h to obtain homogenized gasification slag melt. (3) Using a platinum crucible, the homogenized gasified slag melt from (2) was spun into continuous fiber filaments with a diameter of 15.3 μm at 1320 °C and a speed of 1000 m / min. The strength was 1537 MPa without the application of a wetting agent.

[0026] Example 5: A method for preparing basalt fibers from coal gasification slag: (1) Select the coarse coal gasification slag from Shell gasifier of Lu'an Chemical Group. Its composition characteristics are: Al2O3=28.61wt.%, SiO2 / Al2O3=1.72, Fe2O3=8.1wt.%, and crush it into slag powder below 100 mesh; (2) The slag powder in (1) is heated in an electric resistance furnace at a rate of 5℃ / min. When the temperature reaches 550-600℃, the fine coal gasification slag of the gasifier is added (the mass ratio of fine coal gasification slag to coarse coal gasification slag is 0.8:100). Then, the temperature is continued to be heated to 1600℃ to melt, and the mixture is kept warm and homogenized for 12 h to obtain homogenized gasification slag melt. (3) Using a platinum crucible, spinning was performed at 1380 °C and a speed of 1400 m / min to spin the homogenized gasified slag melt from (2) into continuous fiber filaments with a diameter of 14.9 μm. Fiber samples and microscopic photographs are shown below. Figure 2 As shown. Its strength is 1559 MPa without the application of a wetting agent.

[0027] Comparative Example 1 A method for preparing basalt fibers from coal gasification slag: (1) The coarse coal gasification slag from the coal-water slurry gasifier of Yulin Energy and Chemical Group was selected. Its composition characteristics were: Al2O3=15.99wt.%, SiO2 / Al2O3=2.85, Fe2O3=16.32.4 wt.%, which was crushed into slag powder below 100 mesh. (2) The slag powder in (1) is heated and melted in an electric resistance furnace at a rate of 5℃ / min to 1600℃, and kept at the temperature for 12 h for homogenization treatment to obtain homogenized gasified slag melt; (3) Using a platinum crucible, the homogenized gasified slag melt from (2) was spun into continuous fiber filaments with a diameter of 22.8 μm at 1400 m / min and 1380 °C. The strength was 506 MPa without the application of a wetting agent.

[0028] Comparative Example 2 The difference from Example 5 is that the temperature range for adding coal gasification fine slag in step (2) is 450-500℃, and the diameter of the resulting continuous fiber is 17.5 μm. Without the application of a wetting agent, its strength is 1390 MPa.

[0029] A comparison of Examples 4 and 5 with Examples 1-3 shows that adding a suitable proportion of coal gasification fine slag in the 550-600℃ temperature range further removes residual carbon, increases the overall homogenization effect, significantly increases the ratio of strength to fiber diameter, and also significantly increases the absolute value of strength.

[0030] The comparison between Example 2 and Comparative Example 1 shows that the Fe2O3 content in the coarse coal gasification slag is too high, which leads to a significant decrease in strength after spinning.

[0031] The comparison between Example 5 and Comparative Example 2 shows that adding coal gasification slag at excessively low temperatures cannot enhance homogenization, and therefore cannot improve fiber strength.

[0032] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing basalt fibers from coal gasification slag, characterized in that, Includes the following steps: S1: Crush the coarse slag from coal gasification; S2: The crushed coal gasification slag is heated to melt, and then kept at the temperature to obtain a homogenized melt; S3: The melt is melt-spun into basalt fibers.

2. The method according to claim 1, characterized in that, In step S1, the composition of the coal gasification coarse slag satisfies: Al2O3≤30 wt.%, SiO2 / Al2O3≥1.65, Fe2O3≤15 wt.%.

3. The method according to claim 1, characterized in that, In step S1, the particle size of the coal gasification coarse slag after crushing is below 100 mesh.

4. The method according to claim 1, characterized in that, In step S2, before heating the crushed coarse coal gasification slag to the melting temperature, fine coal gasification slag is added at a temperature between 550-800°C.

5. The method according to claim 4, characterized in that, The mass ratio of the fine coal gasification slag to the coarse coal gasification slag is (0.2-1):

100.

6. The method according to claim 4 or 5, characterized in that, The particle size of the coal gasification slag is below 100 mesh.

7. The method according to any one of claims 1-5, characterized in that, In step S2, the temperature at which the material is heated to the melting point is 1450-1650°C.

8. The method according to any one of claims 1-5, characterized in that, In step S2, the heat preservation time is 6-12 hours.

9. The method according to any one of claims 1-5, characterized in that, In step S3, the melt spinning apparatus includes one of a platinum crucible, a platinum substitute crucible, a tank furnace, a high-speed centrifugal spinning machine, or a high-speed blower.

10. The method according to any one of claims 1-5, characterized in that, In step S3, the basalt fiber includes continuous fiber filaments or fixed-length fiber filaments.

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