Method for synergistically preparing aluminum silicate fiber by using coal-based solid waste

Abstract

The invention discloses a method for synergistically preparing aluminum silicate fibers by using coal-based solid waste, and relates to the field of inorganic non-metallic materials. The preparation method comprises the following steps: pretreating raw materials: crushing coal gangue to below 100 meshes, calcining at 700-900 DEG C for 1-2 hours for activation, pickling fly ash with 1-12% hydrochloric acid at 40-80 DEG C, and drying to remove CaO and MgO impurities; after the two treatments, the coal gangue accounts for 10%-90%, the fly ash accounts for 90%-10%, and 2%-10% of iron tailings are added to adjust the melt viscosity, so that the mass ratio of Al2O3 to SiO2 in the mixture is 0.8-1.8; melting and fibration: melting the mixture in an electric arc furnace at 1500-1700 DEG C for 1-8 hours, and controlling the melt viscosity to be 2-8 Pa.s; and the molten liquid is fiberized by adopting a blowing or thread throwing process and then cooled to prepare the aluminum silicate fiber, and the obtained fiber has the characteristics of high tensile strength, low heat conductivity coefficient, excellent high-temperature resistance and the like. The method reduces the raw material cost and melting temperature, is high in resource utilization rate, has good economical efficiency and environmental protection property, and is suitable for the fields of high-temperature heat preservation, industrial heat insulation and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic non-metallic materials, in particular to a method for preparing aluminum silicate fibers by using coal-based solid waste. BACKGROUND

[0002] With the wide application of coal resources exploitation and thermal power generation, the output of industrial solid waste such as coal gangue and fly ash is increasing. The traditional treatment method has low value and heavy pollution, and has not realized effective resource utilization. At the same time, the traditional preparation of aluminum silicate fibers relies on non-renewable hard clay resources, and the melting temperature is as high as 2000℃, which has the problems of energy waste and environmental emission.

[0003] In the prior art, patent CN109183194A discloses a method for preparing aluminum silicate fibers by using coal gangue as the main raw material and adopting alkali dissolution and electrospinning, but the fly ash is not used cooperatively; CN102276141A proposes a method for preparing slag fibers by using hot coal cinder and fly ash, but the composition of coal gangue is not covered. Therefore, it is urgent to develop a green and efficient method for preparing aluminum silicate fibers by using coal-based solid waste cooperatively, which can be widely promoted. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies in the prior art, the present application provides a method for preparing aluminum silicate fibers by using coal-based solid waste cooperatively, which solves the problems of traditional aluminum silicate fiber preparation relying on non-renewable hard clay resources, high melting temperature of 2000℃, and energy waste and environmental emission.

[0006] (II) Technical solutions

[0007] To achieve the above purpose, the present application is realized by the following technical solutions: a method for preparing aluminum silicate fibers by using coal-based solid waste cooperatively, comprising the following steps,

[0008] Step S1, raw material pretreatment: crushing the coal gangue to 100 mesh or less, calcining at 700-900℃ for 1-2 hours for activation, and acid washing the fly ash with 1%-12% hydrochloric acid at 40-80℃ and drying to remove CaO and MgO impurities;

[0009] Step S2, mixing the two kinds of treated materials, wherein the coal gangue accounts for 10%-90%, the fly ash accounts for 90%-10%, and 2%-10% iron tailings are added to adjust the melt viscosity, so that the mass ratio of Al2O3 to SiO2 in the mixture is 0.8-1.8;

[0010] Step S3, melting and fiberization: melting the mixture in an electric arc furnace at 1500-1700℃ for 1-8 hours, and controlling the melt viscosity to be 2-8 Pa·s.

[0011] Step S4: The molten liquid is fiberized by blowing or spinning and then cooled to obtain aluminum silicate fiber.

[0012] As a further preferred embodiment of the present invention, the blowing process involves spraying molten liquid through a spinneret into filaments under high pressure of 0.7-1.8 MPa and then cooling it.

[0013] As a further preferred embodiment of the present invention, the spinning process involves spinning the molten liquid into fibers using a centrifugal spinning machine with a rotation speed of 4000-8000 rpm.

[0014] As a further preferred embodiment of the present invention, the coal gangue contains 16%-36% Al2O3 and 52%-65% SiO2.

[0015] As a further preferred embodiment of the present invention, the fly ash contains 30%-50% Al2O3.

[0016] A type of aluminum silicate fiber prepared using a coal-based solid waste co-processing method has a fiber diameter of 2-15 μm and a tensile strength ≥100 MPa.

[0017] (III) Beneficial Effects

[0018] This invention provides a method for co-preparing aluminosilicate fibers using coal-based solid waste. It offers the following advantages: The aluminosilicate fibers prepared using this method, after processing through cotton collection, needle punching, and curing, can be used to produce a series of refractory and thermal insulation materials, including aluminosilicate fiber needle-punched blankets, nanofiber filter tubes, tube shells, nanoplates, fiber modules, and irregularly shaped parts. Compared with traditional organic materials, it possesses excellent non-combustibility, high temperature resistance (≥1300℃), and durability, with a thermal conductivity as low as ≤0.05 W / (m·K). It can be widely used in steel kiln linings, aerospace thermal protection layers, petrochemical pipeline insulation, and industrial high-temperature filtration. This invention uses coal gangue (Al2O3 16%-36%) and fly ash (Al2O3 30%-50%) as core raw materials. Through synergistic activation-melt tempering technology, it achieves an Al / Si comprehensive utilization rate of ≥90% and an iron tailings addition of ≤10%, significantly reducing dependence on natural minerals. In terms of process, the melting temperature is reduced by 50-100℃ compared to traditional processes, energy consumption is reduced by 15%-20%, pickling wastewater is recycled, and waste gas is purified, achieving clean production. The resulting fibers have a tensile strength ≥100MPa, and production costs are reduced by 30%-40% compared to traditional processes. Each ton of product can consume 1.8 tons of coal gangue and 1.2 tons of fly ash, reducing solid waste accumulation by 3 tons, promoting the construction of "zero-waste cities," helping to achieve "dual-carbon" goals, and providing key technological support for the transformation from a resource-based economy to a circular economy. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 This invention provides a technical solution: a method for co-preparing aluminosilicate fibers using coal-based solid waste, comprising the following steps:

[0022] Step S1, raw material pretreatment: crush coal gangue to below 100 mesh, calcine at 700-900℃ for 1-2 hours for activation, and acid wash and dry fly ash with 1%-12% hydrochloric acid at 40-80℃ to remove CaO and MgO impurities.

[0023] In step S2, the above two processed materials are mixed with 10%-90% coal gangue, 90%-10% fly ash, and 2%-10% iron tailings to adjust the melt viscosity, so that the mass ratio of Al2O3 to SiO2 in the mixture is 0.8-1.8.

[0024] Step S3, Melting and Fiberization: Melt the mixture in an electric arc furnace at 1500-1700℃ for 1-8 hours, controlling the melt viscosity to be 2-8 Pa·s;

[0025] Step S4: The molten liquid is fiberized by blowing or spinning and then cooled to obtain aluminum silicate fiber.

[0026] The blowing process involves spraying molten liquid through a spinneret to form filaments under high-pressure gas of 0.7-1.8 MPa, followed by cooling.

[0027] The spinning process involves spinning molten liquid into fibers using a centrifugal spinning machine with a rotation speed of 4000-8000 rpm.

[0028] The Al2O3 content in coal gangue is 16%-36%, and the SiO2 content is 52%-65%.

[0029] The Al2O3 content in fly ash is 30%-50%.

[0030] A type of aluminum silicate fiber prepared using a coal-based solid waste co-processing method has a fiber diameter of 2-15 μm and a tensile strength ≥100 MPa.

[0031] All raw materials used in the examples came from Yangquan. The coal gangue came from a coal mine in Yangquan, and the fly ash came from a thermal power plant in Yangquan. The main components of the coal gangue by weight percentage were: SiO2: 52.3%, Al2O3: 31.6%, Fe2O3: 6.8%, CaO: 1.5%, K2O: 1.8%, TiO2: 0.9%, and LOI: 5.1%.

[0032] The main components of fly ash by weight percentage are: SiO2: 48.5%, Al2O3: 33.5%, Fe2O3: 5.8%, CaO: 8.6%, MgO: 1.2%, SO3: 0.7%, LOI: 1.7%.

[0033] Example 1: Adjustment of acid-washed fly ash with iron tailings

[0034] Raw material processing

[0035] Coal gangue: crushed to below 100 mesh, calcined at 850℃ for 1.5 hours for activation, the Fe2O3 content in the activated coal gangue decreased from 6.8% to 4.2%;

[0036] Fly ash: Pickling with 5% hydrochloric acid (60℃) for 1 hour reduces CaO from 8.6% to 2.5%.

[0037] Mixing ratio

[0038] Coal gangue: fly ash = 1:2 (weight percentage), with 5% iron tailings added, and the molar ratio of Al2O3 / SiO2 in the mixture controlled to be approximately 1.6.

[0039] Melting and Fiberization

[0040] Melting temperature: Melt the mixture completely at 1600℃ for 1 hour;

[0041] Fiberization process: The molten liquid is brushed through a four-roll centrifugal spinning machine at a speed of 4500 rpm to obtain aluminum silicate fibers with a diameter of 5-8 μm.

[0042] The aluminum silicate fibers prepared by this method have a tensile strength of 180 MPa, a thermal conductivity of 0.04 W / (m·K), and a slag ball content of less than 5%, and can be used in temperature environments above 1300℃.

[0043] Example 2: Compensation of Unwashed Fly Ash with Iron Tailings

[0044] Raw material processing

[0045] Coal gangue: crushed to below 100 mesh, calcined at 800℃ for 2 hours for activation, the Fe2O3 content in the activated coal gangue powder is reduced to 4.5%;

[0046] Fly ash: Use directly.

[0047] Mixing ratio

[0048] Coal gangue: fly ash = 1:1.5 (weight percentage), with 3% iron tailings and 2% borax added as flux.

[0049] Melting and Fiberization

[0050] Melting temperature: The mixture is fully melted at 1550℃ for 1.2 hours;

[0051] Fiberization process: The molten liquid is spun into fibers by a four-roll centrifugal spun machine with a rotation speed of 4000 rpm to obtain aluminum silicate fibers with a diameter of 6-10 μm and a tensile strength of 120 MPa.

[0052] This method eliminates the step of acid washing fly ash, which can reduce costs by about 12%, but at the same time it leads to a slight decrease in fiber strength. It is suitable for medium-temperature fields with temperatures ≤1100℃.

[0053] Example 3: High-alumina coal gangue plus low-calcium fly ash

[0054] Raw material processing:

[0055] Coal gangue: The coal gangue is carefully selected, and the high-alumina portion with an Al2O3 content greater than 35% is selected. After activation by calcination at 800℃ for 2 hours, the Al2O3 content can reach 38.2%.

[0056] Fly ash: Acid washing with 5% hydrochloric acid at 60℃ reduces CaO from 8.6% to below 5%.

[0057] Mixing ratio

[0058] Coal gangue: fly ash = 1:3 (by weight), with 2% iron tailings added to adjust the melt viscosity.

[0059] Melting and Fiberization

[0060] Melting temperature: Melt the mixture completely at 1650℃ for 2 hours;

[0061] Fiberization process: The molten liquid is spun into fibers by a four-roll centrifugal spun machine with a rotation speed of 6000 rpm to obtain ultrafine aluminum silicate fibers with a diameter of 3-5 μm.

[0062] The ultrafine aluminosilicate fibers prepared by this method can be used in temperature environments of ≥1500℃ and can be applied to aerospace thermal insulation materials.

[0063] Example 4: High-speed railway coal gangue enhanced by acid washing

[0064] Raw material processing

[0065] Coal gangue: crushed to below 100 mesh, calcined at 800℃ for 2 hours for activation, the Fe2O3 content in the activated coal gangue powder is reduced to 4.5%;

[0066] Fly ash: Enhanced acid washing with 10% hydrochloric acid at 80℃ for 2 hours reduced the CaO content in fly ash from 8.6% to 1.8%.

[0067] Mixing ratio

[0068] Coal gangue: fly ash = 1:1 (by weight), with 8% iron tailings and 1% carbon powder added.

[0069] Melt control

[0070] Melting temperature: The mixture is fully melted at 1700℃ for 2 hours;

[0071] Fiberization process: The molten liquid is blown into fibers using a high-pressure airflow of 1.2 MPa to obtain aluminum silicate fibers with a diameter of 10-15 μm.

[0072] Although the processing cost of the aluminosilicate fiber prepared by this method increases by 20%, the product premium is about 30%, and the product can replace some imported refractory fibers.

[0073] Example 5: Partial replacement of fly ash with tailings synergy

[0074] This embodiment mainly uses three types of solid waste for co-processing: coal gangue, fly ash, and steel slag (chemical composition: CaO 47.2%, SiO2 18.3%, Fe2O3 21.8%, MgO 6.4%, Al2O3 3.3%, MnO 1.4%, and other 1.6%).

[0075] Raw material processing

[0076] The coal gangue was crushed to below 100 mesh and activated by calcination at 800℃ for 2 hours; the fly ash was left untreated; the steel slag was subjected to magnetic separation to remove iron, so that Fe2O3 was less than 1%, and then crushed to 200 mesh.

[0077] Mixing ratio

[0078] The proportions of the three raw materials are as follows: coal gangue: fly ash: iron tailings = 5:3:2 (by weight).

[0079] Melt control

[0080] Segmented melting: First, the mixture of coal gangue and fly ash is pre-melted at 1500℃ for 1 hour, then steel slag of the corresponding proportion is added, and then the temperature is raised to 1600℃ for 2 hours to complete the final melting.

[0081] Fiberization process: The molten liquid is spun into fibers by a four-roll centrifugal spun machine with a rotation speed of 6000 rpm to obtain ultraaluminosilicate fibers with a diameter of 3-5 μm.

[0082] This method achieves a total solid waste utilization rate of over 95%, reducing raw material costs by approximately 15% compared to the method of adding pure iron tailings.

[0083] Key process comparison

[0084]

[0085] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0086] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for co-preparing aluminosilicate fibers using coal-based solid waste, characterized in that: It includes the following steps, Step S1, raw material pretreatment: crush coal gangue to below 100 mesh, calcine at 700-900℃ for 1-2 hours for activation, and acid wash and dry fly ash with 1%-12% hydrochloric acid at 40-80℃ to remove CaO and MgO impurities. Step S2, of the two processed products mentioned above, Coal gangue accounts for 10%-90%, fly ash accounts for 90%-10%, and 2%-10% iron tailings are added to adjust the melt viscosity so that the mass ratio of Al2O3 to SiO2 in the mixture is 0.8-1.

8. Step S3, Melting and Fiberization: Melt the mixture in an electric arc furnace at 1500-1700℃ for 1-8 hours, controlling the melt viscosity to be 2-8 Pa·s; Step S4: The molten liquid is fiberized by blowing or spinning and then cooled to obtain aluminum silicate fiber.

2. The method for co-preparing aluminosilicate fibers using coal-based solid waste according to claim 1, characterized in that: The blowing process involves spraying molten liquid through a spinneret to form filaments under high-pressure gas of 0.7-1.8 MPa, followed by cooling.

3. The method for co-preparing aluminosilicate fibers using coal-based solid waste according to claim 1, characterized in that: The spinning process involves spinning molten liquid into fibers using a centrifugal spinning machine with a rotation speed of 4000-8000 rpm.

4. The method for co-preparing aluminosilicate fibers using coal-based solid waste according to claim 1, characterized in that: The coal gangue contains 16%-36% Al2O3 and 52%-65% SiO2.

5. The method for co-preparing aluminosilicate fibers using coal-based solid waste according to claim 1, characterized in that: The fly ash contains 30%-50% Al2O3.

6. An aluminosilicate fiber manufactured according to any one of claims 1-5, characterized in that: The fiber diameter is 2-15μm and the tensile strength is ≥100MPa.

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