Preparation method and application of red mud-based desulfurized gypsum and fly ash geopolymer serving as damming material

Abstract

The invention provides a preparation method and application of a red mud-based desulfurized gypsum and fly ash geopolymer serving as a damming material, and belongs to the technical field of geotechnical engineering. The geopolymer material comprises the following raw materials: Bayer process red mud, desulfurized gypsum and fly ash. The mass ratio of the Bayer process red mud to the desulfurized gypsum to the fly ash is 3: 4: 3. According to the invention, red mud, desulfurized gypsum and fly ash are taken as basic raw materials, particle size component proportion distribution of the red mud, desulfurized gypsum and fly ash and mass ratio of each material are controlled, cold regeneration mixing equipment is used for uniform mixing, and vibration rolling equipment is used for vibration rolling, so that the mixture is in uniform contact; under the alkaline action in the red mud, the mixed material is self-excited to form a geopolymer, and the geopolymer has the characteristics of certain strength and low permeability. The permeability coefficient of the geopolymer is smaller than 1 * 10 <-4 > cm / s, the compaction degree is larger than 0.96, the mechanical property is good, and the requirements of dam body backfilling for permeability and compaction characteristics of materials can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering, and particularly relates to a preparation method and application of red mud-based desulfurized gypsum and fly ash geopolymers as dam-building materials. Background Art

[0002] The emissions of red mud reach tens of millions of tons. At the same time, a large amount of low-quality fly ash and desulfurized gypsum waste are stored during the production process in the power plants supporting the aluminum plants. These solid wastes cannot be fully and effectively utilized and can only rely on stacking occupying land. Therefore, how to efficiently and environmentally treat these solid wastes has become a difficult problem that needs to be solved urgently. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a preparation method and application of red mud-based desulfurized gypsum and fly ash geopolymers as dam-building materials.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] One technical solution of the present invention is a red mud-based desulfurized gypsum and fly ash geopolymer as a dam-building material, and the raw materials include Bayer red mud, desulfurized gypsum, and fly ash; the mass ratio of the Bayer red mud, desulfurized gypsum, and fly ash is 3:4:3;

[0006] The Bayer red mud is formed by the alumina Bayer process and has strong alkalinity. According to the particle size distribution, the Bayer red mud includes red mud 1, red mud 2, and red mud 3. The particle size of red mud 1 is less than 0.005 mm, the particle size of red mud 2 is greater than or equal to 0.005 mm and less than 0.075 mm, and the particle size of red mud 3 is greater than or equal to 0.075 mm and less than 2 mm;

[0007] The desulfurized gypsum includes gypsum 1 and gypsum 2. The particle size of gypsum 1 is less than 0.005 mm, and the particle size of gypsum 2 is greater than or equal to 0.005 and less than 0.075 mm;

[0008] The fly ash includes fly ash 1, fly ash 2, and fly ash 3. The particle size of fly ash 1 is less than 0.005 mm, the particle size of fly ash 2 is greater than or equal to 0.005 mm and less than 0.075 mm, and the particle size of fly ash 3 is greater than or equal to 0.075 and less than 0.5 mm.

[0009] In some embodiments of the present invention, by mass, in the Bayer red mud, red mud 1: 60 - 65 parts, red mud 2: 20 - 25 parts, red mud 3 2 - 10 parts.

[0010] In some embodiments of the present invention, by mass, in the desulfurized gypsum, gypsum 1: 15 - 20 parts, gypsum 2: 80 - 85 parts.

[0011] In some embodiments of the present invention, the fly ash comprises, by mass parts, fly ash 1: 0-5 parts, fly ash 2: 80-85 parts, and fly ash 3: 10-20 parts.

[0012] The second technical solution of this invention is a method for preparing red mud-based desulfurization gypsum and fly ash geopolymer as dam construction materials, comprising the following steps:

[0013] Bayer red mud, desulfurized gypsum and fly ash are mixed evenly and spread out, then finely mixed. After fine mixing, polymer filler is obtained.

[0014] The filler material is spread in layers and vibrated and compacted to obtain the mixture of red mud-based desulfurization gypsum and fly ash geopolymer. The moisture content W of the mixture is... op =25.5% ± 3.

[0015] In some embodiments of the present invention, the paving thickness in the layered paving is 30cm; the fine mixing is carried out using a cold recycling mixer with a travel speed of 6km / h, a milling depth of 300mm-330mm, and 4 passes of fine mixing; the vibratory compaction is carried out using a 26t vibratory roller with a travel speed of 4-6km / h, an amplitude of 1.8-2.0mm, a frequency of 30Hz, and 8 passes of compaction. The vibration excitation force for the first and second passes is 420KN, the vibration excitation force for the third, fourth, fifth, sixth, and seventh passes is 310KN, and the static pressure for the eighth pass is 260KN.

[0016] The third technical solution of this invention is a method for preparing red mud-based desulfurized gypsum and fly ash geopolymer as dam construction materials and their application.

[0017] The present invention discloses the following technical effects:

[0018] This invention uses Bayer process red mud, desulfurized gypsum, and fly ash as basic raw materials. By controlling the particle size distribution and mass ratio of red mud, gypsum, and fly ash, and using cold recycling mixing equipment for mixing and vibratory compaction equipment for compaction, the mixture is made into uniformly contacted materials. The fly ash in the mixture contains amorphous aluminosilicate active materials. These active materials form geopolymer materials under the strongly alkaline activation conditions of red mud. The permeability coefficient of this geopolymer is less than 1×10⁻⁶. -4 With a density of cm / s and a compaction degree greater than 0.96, it has good mechanical properties and can meet the requirements of dam backfill for material permeability and compaction characteristics.

[0019] The red mud-gypsum-fly ash geopolymer material provided by this invention requires specific components with specific content and particle size to achieve good overall interaction. Experimental results show that if the type, particle size, and proportion of raw materials differ from those of this invention, the performance of the resulting geopolymer will fail to meet the requirements for dam backfill materials.

[0020] This invention can solve the problem of land occupation caused by dam construction, while effectively utilizing solid waste such as red mud, fly ash, and gypsum. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] The red mud-based desulfurized gypsum and fly ash geopolymer material provided by this invention meets the requirements of the dam body for material permeability coefficient. It is used for backfilling and compaction of the dam body, which not only solves the problem of land occupation caused by dam construction, but also effectively utilizes solid waste such as red mud, fly ash and gypsum.

[0027] Specifically, the preparation method of the red mud-based desulfurization gypsum and fly ash geopolymer material of the present invention includes the following steps:

[0028] (1) Screening experiments were conducted on Bayer red mud, desulfurized gypsum and fly ash to determine the particle size distribution of each material, and raw materials that meet the particle size distribution characteristics were selected as mixing materials.

[0029] The Bayer process red mud includes red mud 1, red mud 2 and red mud 3. The particle size of red mud 1 is less than 0.005 mm, the particle size of red mud 2 is greater than or equal to 0.005 mm and less than 0.075 mm, and the particle size of red mud 3 is greater than or equal to 0.075 mm and less than 2 mm. By mass parts, red mud 1 is 60-65 parts, red mud 2 is 20-25 parts, and red mud 3 is 2-10 parts.

[0030] The desulfurized gypsum includes gypsum 1 and gypsum 2. The particle size of gypsum 1 is less than 0.005 mm, and the particle size of gypsum 2 is greater than or equal to 0.005 mm and less than 0.075 mm. By mass parts, gypsum 1 is 115-20 parts and gypsum 2 is 80-85 parts.

[0031] Fly ash includes fly ash 1, fly ash 2 and fly ash 3. The particle size of fly ash 1 is less than 0.005 mm, the particle size of fly ash 2 is greater than or equal to 0.005 mm and less than 0.075 mm, and the particle size of fly ash 3 is greater than or equal to 0.075 mm and less than 0.5 mm. By mass parts, fly ash 10-5 parts, fly ash 2 80-85 parts, and fly ash 3 10-20 parts.

[0032] (2) Measure the density of each type of material that meets the requirements, and calculate the required volume of each type of material based on the mass ratio of Bayer red mud: desulfurized gypsum: fly ash = 3:4:3.

[0033] (3) Use a loader to initially mix Bayer red mud, desulfurized gypsum and fly ash according to the calculated volume. After mixing, spread the mixture to a thickness of 30cm.

[0034] (4) Use a cold recycling mixer to finely mix the paved material. The cold recycling mixer travels at a speed of 6 km / h and the mixing passes are 4.

[0035] (5) After mixing, the moisture content should be measured. The moisture content after mixing should be 25.5±3%. After meeting the requirements, a 26t vibratory roller is used to compact the fill material. The number of compaction passes is 8. The roller travel speed is 4-6 km / h, the amplitude is 1.8-2.0 mm, and the frequency is 30 Hz. The excitation force for the first and second passes is 420 KN, the excitation force for the third, fourth, fifth, sixth and seventh passes is 310 KN, and the static pressure for the eighth pass is 260 KN.

[0036] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0037] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] The raw materials used were Bayer red mud, desulfurization gypsum, fly ash, and slag waste generated in the production of an aluminum power plant in Shandong. The materials were configured in different proportions, and materials configured in the same proportion were selected with different particle size compositions. The configuration proportions and particle size compositions are shown in Table 1.

[0040] Table 1. Raw material configuration ratio and particle size distribution

[0041]

[0042]

[0043]

[0044] (1) Prepare the above nine groups of materials according to the required configuration ratio.

[0045] (2) Use a raw material mixer to initially mix the nine groups of materials. After mixing, use a paver to spread the material to a thickness of 30cm.

[0046] (3) Use a cold recycling mixer to finely mix the materials of the nine groups of paving materials. The cold recycling mixer travels at a speed of 6 km / h for each group of materials and the mixing is done 4 times.

[0047] (4) After mixing, the moisture content was measured. The moisture content of the first group of materials was 22.7%, the second group of materials was 28.5%, the third group of materials was 25.6%, the fourth group of materials was 22.8%, the fifth group of materials was 28.8%, the sixth group of materials was 25.9%, the seventh group of materials was 16.5%, the eighth group of materials was 22.5%, and the ninth group of materials was 19.4%. After the moisture content was measured, a 26t vibratory roller was used to compact the nine groups of materials. The roller travel speed was 6km / h, and the number of compaction passes was 8. The excitation force for the first and second passes was 420KN, the excitation force for the third, fourth, fifth, sixth, and seventh passes was 310KN, and the static pressure for the eighth pass was 260KN.

[0048] (5) After compaction is completed and the mixture is cured for 7 days, the nine groups of materials are subjected to sand cone test, permeability coefficient test, direct shear test, consolidation test and light dynamic penetration test respectively. The test results are shown in Table 2.

[0049] Table 2

[0050]

[0051] As shown in Table 2, when the mass ratio of Bayer red mud:desulfurized gypsum:fly ash is 3:4:3, the permeability coefficient and compaction degree of the first and second groups of materials meet the requirements for dam construction. However, the permeability coefficient and compaction degree of the third group, whose particle size of Bayer red mud, desulfurized gypsum, and fly ash is not within the scope of this invention, do not meet the requirements for dam construction. The mechanical properties (shear strength, compression modulus, and light dynamic penetration test) of the first and second groups of materials are similar and significantly better than those of the third group of materials.

[0052] Further analysis of the particle size of materials in groups one, two, and three reveals that when the mass ratio of Bayer red mud, desulfurized gypsum, and fly ash is 3:4:3, the permeability coefficient and compaction degree of the material after being mixed in a cold mixing machine and compacted by a vibratory roller, by controlling the particle size distribution of various materials, meet the requirements for dam construction materials.

[0053] When the mixing ratio of Bayer red mud: desulfurized gypsum: fly ash is 3:3:4, the permeability coefficient of the fourth group of materials meets the requirements for dam construction, but the compaction degree does not meet the requirements for dam construction. The permeability coefficient and compaction degree of the fifth and sixth groups of materials do not meet the requirements for dam construction. This material ratio cannot be used as dam construction material.

[0054] When the mixing ratio of Bayer red mud: slag: desulfurized gypsum: fly ash = 3:2:3:2, the permeability coefficients of the materials in groups seven, eight, and nine do not meet the requirements for dam construction, but the compaction degree does meet the requirements for dam construction. This material ratio cannot be used as dam construction material.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A red mud-based desulfurized gypsum and fly ash geopolymer used as a dam construction material, characterized in that, The raw materials include Bayer red mud, desulfurized gypsum, and fly ash; the mass ratio of the Bayer red mud, desulfurized gypsum, and fly ash is 3:4:

3. The Bayer process red mud includes red mud 1, red mud 2 and red mud 3. The particle size of red mud 1 is less than 0.005 mm, the particle size of red mud 2 is greater than or equal to 0.005 mm and less than 0.075 mm, and the particle size of red mud 3 is greater than or equal to 0.075 mm and less than 2 mm. The desulfurized gypsum includes gypsum 1 and gypsum 2, wherein the particle size of gypsum 1 is less than 0.005 mm, and the particle size of gypsum 2 is greater than or equal to 0.005 mm and less than 0.075 mm. The fly ash includes fly ash 1, fly ash 2 and fly ash 3. The particle size of fly ash 1 is less than 0.005 mm, the particle size of fly ash 2 is greater than or equal to 0.005 mm and less than 0.075 mm, and the particle size of fly ash 3 is greater than or equal to 0.075 mm and less than 0.5 mm.

2. The red mud-based desulfurized gypsum and fly ash geopolymer as a dam construction material according to claim 1, characterized in that, By mass fractions, the Bayer process red mud comprises: Red mud 1: 60-65 parts, Red mud 2: 20-25 parts, and Red mud 3: 2-10 parts.

3. The red mud-based desulfurized gypsum and fly ash geopolymer as a dam construction material according to claim 1, characterized in that, By mass fraction, the desulfurized gypsum comprises gypsum 1: 15-20 parts and gypsum 2: 80-85 parts.

4. The red mud-based desulfurized gypsum and fly ash geopolymer as a dam construction material according to claim 1, characterized in that, By mass fraction, the fly ash comprises fly ash 1: 0-5 parts, fly ash 2: 80-85 parts, and fly ash 3: 10-20 parts.

5. A method for preparing a red mud-based desulfurized gypsum and fly ash geopolymer as a dam construction material, as described in any one of claims 1-4, characterized in that, Includes the following steps: Bayer red mud, desulfurized gypsum and fly ash are mixed evenly and spread out, then finely mixed. After fine mixing, a polymer filler is formed. The polymer filler is spread in layers and vibrated and compacted to obtain the red mud-based desulfurization gypsum and fly ash geopolymer material.

6. The preparation method according to claim 5, characterized in that, In the layered paving, the paving thickness is 30cm; the fine mixing is carried out using a cold recycling mixer with a travel speed of 6km / h, a milling depth of 300mm-330mm, and 4 passes of fine mixing; the vibratory compaction is carried out using a 26t vibratory roller with a travel speed of 4-6km / h, an amplitude of 1.8-2.0mm, a frequency of 30Hz, and 8 passes of compaction. The vibration excitation force for the first and second passes is 420KN, the vibration excitation force for the third, fourth, fifth, sixth, and seventh passes is 310KN, and the static pressure for the eighth pass is 260KN.

7. The application of a red mud-based desulfurized gypsum and fly ash geopolymer as a dam construction material, as described in any one of claims 1-4, in dam body filling.

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