Iron tailing-based geopolymer grouting material and preparation method thereof

Abstract

The invention provides an iron tailing-based geopolymer grouting material and a preparation method thereof. The iron tailing-based geopolymer grouting material comprises the following components in parts by weight: 30-60 parts of iron tailing powder, 15-45 parts of slag, 10-20 parts of fly ash, 5-8 parts of desulfurized gypsum, 17-33 parts of water glass, 2-4 parts of NaOH, 70-80 parts of water and 0.8-1 part of a water reducing agent. According to the iron tailing-based geopolymer grouting material disclosed by the invention, the iron tailings can be used as a gelling admixture to be applied to a geopolymer system, so that the application range of the iron tailings is widened, and a large amount of stockpiling of the iron tailings is reduced; meanwhile, the iron tailing powder, the slag, the fly ash and the desulfurized gypsum are used as main raw materials, mechanical ball milling and alkali excitation are used as activation modes, carbon emission caused by high-temperature calcination activation is avoided while solid waste is digested, the 28d strength of the prepared grouting material can reach 6.94 MPa, the goaf filling requirement is met, and the grouting material has good flowability and is suitable for being used as a grouting material. The material can effectively replace a cement-based material for goaf filling.

Description

Technical Field

[0001] The invention belongs to the technical field of goaf grouting materials, and in particular relates to an iron tailings base polymer grouting material and a preparation method thereof. Background Art

[0002] Mineral mining has provided impetus for the rapid development of industry, and it has also inevitably formed a large number of goafs. Large-scale goafs will cause collapse and damage the surrounding surface environment. Grouting technology can prevent surface collapse and reduce the impact of underground mining activities on the surface environment to a certain extent. It is an effective means to manage the voids in goafs. At present, cement-based materials are the most commonly used grouting materials, and their advantage lies in mature technology. However, the production process of cement will emit a large amount of CO2. Under my country's "dual carbon" goal, traditional high-energy consumption industries must transform to green, so there is an urgent need to study a green and environmentally friendly grouting material.

[0003] Iron tailings are one of the main solid wastes from mining in my country, with an annual output of 4.5 billion tons, but its utilization rate is only 6.79%. In recent years, the storage volume of iron tailings has increased day by day. The storage of tailings not only occupies a large amount of land, but also poses the risk of dam breach and leakage. In addition, the heavy metal elements contained in iron tailings will migrate underground, causing pollution to surrounding water bodies, vegetation, soil, etc. Therefore, it is necessary to promote the comprehensive utilization of iron tailings.

[0004] Geopolymer material is a kind of cementitious material with industrial waste as the main raw material, which can replace cement for the preparation of grouting materials. At present, people often use blast furnace slag, fly ash and other highly active solid waste as raw materials to prepare geopolymer grouting materials. Since iron tailings are inert materials with low reaction activity, they can usually only be used as fine aggregate in engineering practice, which greatly limits the use value of iron tailings. Therefore, how to use iron tailings as a cementitious admixture in the geopolymer system, rather than just as a fine aggregate, is a technical problem that needs to be solved. Summary of the invention

[0005] In view of this, in order to solve the technical problems of limited application scope and low utilization of the above-mentioned iron tailings, the present invention proposes an iron tailings-based polymer grouting material and a preparation method thereof, and applies iron tailings as a cementitious admixture to a geopolymer system, thereby broadening the application scope of iron tailings and reducing the large-scale stockpiling of iron tailings; at the same time, the present invention uses iron tailings powder, slag, fly ash and desulfurized gypsum as main raw materials, and mechanical ball milling and alkali excitation as activation methods to form a grouting material with gelling effect, high compressive strength and good fluidity, which can replace cement-based materials for filling goaf areas.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] On the one hand, the present invention provides an iron tailings-based polymer grouting material, comprising the following components in parts by weight: 30-60 parts of iron tailings powder, 15-45 parts of slag, 10-20 parts of fly ash, 5-8 parts of desulfurized gypsum, 17-33 parts of water glass, 2-4 parts of NaOH, 70-80 parts of water, and 0.8-1 part of a water reducer.

[0008] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the iron tailings are silicon-aluminum tailings, and the total mass fraction of SiO2 and Al2O3 is ≥70%; the iron tailings are treated by mechanical ball milling and have a gray-black solid powder appearance with a specific surface area of ​​700 to 1000 m 2 / kg.

[0009] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the slag is S95 grade ore powder with a specific surface area of ​​≥400m 2 / kg.

[0010] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the fly ash is Class II ash with a specific surface area of ​​≥400m 2 / kg.

[0011] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the desulfurized gypsum is dihydrate gypsum (CaSO4·2H2O) with a purity of ≥90%.

[0012] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the water glass is industrial water glass with a modulus of 3.2, a SiO2 content of 26.2%, and a Na2O content of 8.3%.

[0013] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the NaOH is an analytically pure reagent with a purity of ≥96%.

[0014] In some preferred embodiments of the iron tailings-based polymer grouting material of the present invention, the water reducer is a polycarboxylic acid high-efficiency water reducer, and the water reduction rate is above 20%.

[0015] Another aspect of the present invention provides a method for preparing an iron tailings-based polymer grouting material, comprising the following steps:

[0016] S1. After drying and screening, the iron tailings are mechanically milled in a ball mill to obtain a specific surface area of ​​700-1000m 2 / kg of iron tailings powder;

[0017] S2, 30-60 parts of iron tailings powder, 15-45 parts of slag, 10-20 parts of fly ash and 5-8 parts of desulfurized gypsum weighed in the following parts by weight are mixed evenly to obtain a solid waste raw material;

[0018] S3, mixing 17-33 parts of water glass and 2-4 parts of NaOH weighed in the following parts by weight, stirring until the NaOH solid is completely dissolved and then standing to obtain an alkaline activator;

[0019] S4. Mix 0.8-1 part of water reducing agent and 70-80 parts of water weighed in the following parts by weight;

[0020] S5. Mix the mixed solution of solid waste raw materials, alkali activator, water reducer and water, and stir evenly to obtain the iron tailings base polymer grouting material.

[0021] Compared with the prior art, the iron tailings base polymer grouting material and the preparation method thereof described in the present invention have the following advantages:

[0022] (1) In the iron tailings-based geopolymer grouting material of the present invention, the iron tailings are mechanically ball-milled and activated to make the iron tailings have volcanic ash activity, and can be used as a cementitious admixture in the geopolymer system instead of just as an aggregate, thereby broadening the application scope of the iron tailings, improving the utilization rate of the iron tailings, and reducing the stockpiling amount of the iron tailings;

[0023] (2) The iron tailings-based polymer grouting material of the present invention uses iron tailings powder, slag, fly ash and desulfurized gypsum as main raw materials. The iron tailings activated by mechanical ball milling and other main solid waste raw materials are activated by a composite alkali activator composed of water glass and NaOH to form a grouting material with a gelling effect. Under the action of the alkali activator, the Si-O bonds and Al-O bonds on the surface of the iron tailings particles are destroyed, generating a large amount of [SiO4] 4- 、[AlO4] 5- Tetrahedral monomers, these monomers are in the high calcium environment provided by slag and SO4 provided by desulfurized gypsum. 2- In the environment, it repolymerizes to form needle-like ettringite (AFt) and flocculent calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) gel, forming a slurry stone body with high strength, which makes the grouting material have good compressive strength;

[0024] (3) In the iron tailings base polymer grouting material of the present invention, fly ash is a fine glassy spherical particle, which can play a "ball effect" in the system and has a certain improvement effect on the flow properties of the slurry. At the same time, [SiO4] 4- It can reduce the mutual stress between particles and further improve the fluidity of the slurry, making the grouting material have good fluidity;

[0025] (4) The iron tailings base polymer grouting material described in the present invention uses a variety of solid wastes as raw materials, and after compounding, obtains a grouting material with high compressive strength and good fluidity. At the same time, the present invention does not add cement clinker, nor does it use high-temperature calcination activation method. It is more low-carbon, green, and environmentally friendly, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the particle size distribution diagram of the original iron tailings and the iron tailings powder after mechanical activation.

[0027] Figure 2 The XRD diagram of the original iron tailings and the iron tailings powder after mechanical activation.

[0028] Figure 3 This is the XRD pattern of the iron tailings-based polymer grouting material 28d prepared in Example 1.

[0029] Figure 4 This is the SEM image of the iron tailings base polymer grouting material 28d prepared in Example 1.

[0030] Figure 5 This is the EDS image of the iron tailings base polymer grouting material 28d prepared in Example 1. DETAILED DESCRIPTION

[0031] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0032] The present invention will be described in detail below with reference to the embodiments.

[0033] Examples 1 to 7

[0034] In Examples 1 to 7, unless otherwise specified, the preparation process of the iron tailings-based polymer grouting material is as follows:

[0035] S1, after drying and screening the iron tailings, use a ball mill to perform mechanical ball milling for 60 minutes to obtain iron tailings powder;

[0036] S2, mixing the weighed iron tailings powder, slag, fly ash and desulfurized gypsum evenly to obtain a solid waste raw material;

[0037] S3, mixing the weighed water glass and NaOH, stirring until the NaOH solid is completely dissolved and then standing for 24 hours to obtain an alkaline activator;

[0038] S4, mix the weighed water reducer and water evenly;

[0039] S5. Put the solid waste raw materials into a stirring pot and stir at a low speed for 30 seconds. After stirring evenly, add a mixed solution of alkali activator, water reducer and water, mix, and then stir at a low speed for 120 seconds, and then stir at a high speed for 120 seconds to obtain the iron tailings base polymer grouting material.

[0040] The iron tailings were dried, screened, and then mechanically milled in a ball mill. The iron tailings powder obtained was a gray-black solid powder with a specific surface area of ​​820 m 2 / kg (the particle size distribution and XRD diagram of the original iron tailings and the iron tailings powder after mechanical activation are shown in Figure 1 and Figure 2 ) The slag is S95 grade ore powder, with a white solid powder appearance and a specific surface area of ​​450m 2 / kg; fly ash is Class F II ash, with a gray-black solid powder appearance and a specific surface area of ​​416m 2 / kg; Desulfurized gypsum dihydrate gypsum, white solid powder, with a specific surface area of ​​370m 2 / kg; water glass is industrial water glass with a modulus of 3.2, a SiO2 content of 26.2%, and a Na2O content of 8.3%; NaOH is an analytical reagent with a purity of ≥96%; the water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of more than 20%; the specific ingredients of iron ore tailings powder, slag, fly ash and desulfurized gypsum are shown in Table 1;

[0041] chemical composition

[0042]

[0043] The specific proportions of iron tailings powder, slag, fly ash, desulfurized gypsum, water glass, NaOH, water reducing agent and water in Examples 1 to 7 are shown in Table 2;

[0044] The fluidity and compressive strength properties of the iron tailings base polymer grouting materials prepared in Examples 1 to 7 were tested:

[0045] The test method for fluidity is based on the "Standard for Fluidity of Cement Mortar" (GB / T 2419-2005). The truncated cone mold is used to determine the fluidity of the slurry;

[0046] The compressive strength test method is to test the 7d and 28d compressive strength of the mortar stone body according to the "Test Method for Cement Mortar Strength (ISO Method)" (GB / T17671-2021);

[0047] The test results are shown in Table 2. The XRD pattern of the iron tailings base polymer grouting material 28d prepared in Example 1, the SEM pattern of 28d and the EDS pattern of 28d are shown in Table 2. Figure 3 , Figure 4 and Figure 5 shown.

[0048] Table 2 The distribution ratio of each group in Examples 1 to 7 and the performance data of the grouting materials obtained

[0049]

[0050]

[0051] It can be seen from Table 2 that the iron tailings base polymer grouting materials prepared in Examples 1 to 7 have good fluidity and compressive strength, and the best 28d compressive strength can reach 6.94 MPa, which meets the use requirements of grouting materials in goaf areas.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An iron tailings base polymer grouting material, characterized in that: The invention comprises the following components in parts by weight: 30-60 parts of iron tailings powder, 15-45 parts of slag, 10-20 parts of fly ash, 5-8 parts of desulfurized gypsum, 17-33 parts of water glass, 2-4 parts of NaOH, 70-80 parts of water and 0.8-1 part of water reducing agent.

2. The iron tailings base polymer grouting material according to claim 1, characterized in that: The iron tailings are silicon-aluminum tailings, with the total mass fraction of SiO2 and Al2O3 being ≥70%; the iron tailings are treated by mechanical ball milling, with a specific surface area of ​​700-1000m 2 / kg.

3. The iron tailings base polymer grouting material according to claim 1, characterized in that: The slag is S95 grade ore powder with a specific surface area of ​​≥400m 2 / kg.

4. The iron tailings base polymer grouting material according to claim 1, characterized in that: The fly ash is Class II ash, with a specific surface area of ​​≥400m 2 / kg.

5. The iron tailings base polymer grouting material according to claim 1, characterized in that: The desulfurized gypsum is dihydrate gypsum with a purity of ≥90%.

6. The iron tailings base polymer grouting material according to claim 1, characterized in that: The water glass is industrial water glass with a modulus of 3.2, a SiO2 content of 26.2%, and a Na2O content of 8.3%.

7. The iron tailings base polymer grouting material according to claim 1, characterized in that: The NaOH is an analytically pure reagent with a purity of ≥96%.

8. The iron tailings base polymer grouting material according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, and the water reducing rate is above 20%.

9. A method for preparing an iron tailings-based polymer grouting material, characterized in that: The steps include: S1. After drying and screening, the iron tailings are mechanically milled in a ball mill to obtain a specific surface area of ​​700-1000m 2 / kg of iron tailings powder; S2, 30-60 parts of iron tailings powder, 15-45 parts of slag, 10-20 parts of fly ash and 5-8 parts of desulfurized gypsum weighed in the following parts by weight are mixed evenly to obtain a solid waste raw material; S3, mixing 17-33 parts of water glass and 2-4 parts of NaOH weighed in the following parts by weight, stirring until the NaOH solid is completely dissolved and then standing to obtain an alkaline activator; S4. Mix 0.8-1 part of water reducing agent and 70-80 parts of water weighed in the following parts by weight; S5. Mix the mixed solution of solid waste raw materials, alkali activator, water reducer and water, and stir evenly to obtain the iron tailings base polymer grouting material.

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