Low-carbon concrete suitable for mine engineering and preparation method thereof

Abstract

The invention discloses low-carbon concrete suitable for mine engineering. The concrete is prepared from the following components in parts by weight: 700 to 750 parts of lithium slag powder, 385 to 770 parts of niobium-tantalum tailing sand, 140 to 160 parts of silica fume, 100 to 200 parts of third powder, 200 to 605 parts of river sand, 15 to 20 parts of a water reducing agent and 160 to 190 parts of water. The concrete is low-carbon, environment-friendly, high in compressive strength and good in fluidity, can be used as a supplementary material in engineering application of local mine recovery and excavation, realizes waste utilization according to local conditions, and reduces the cost of waste treatment and ecological restoration while reducing the use amount of cement clinker and non-renewable aggregate sand grains. The invention also provides a preparation method of the low-carbon concrete suitable for mine engineering, and the preparation method is simple to operate and suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and in particular relates to low-carbon concrete suitable for mining engineering and a preparation method thereof. Background Art

[0002] my country boasts abundant reserves of niobium and tantalum, particularly in Jiangxi Province, which leads the country in both. The Yichun tantalum-niobium mine, in particular, is the world's largest lepidolite-type niobium-tantalum coexisting deposit. Mining niobium and tantalum is not only a key component of Jiangxi's efforts to leverage its resource advantages and build a "world-class rare metals industrial base," but also a strategic choice for safeguarding the security of key national industrial chains and seizing the commanding heights of new energy and high-tech industries. Large-scale development of lepidolite provides resource support for the new energy industry, consolidating its strategic position in the global mining supply chain.

[0003] However, the substantial increase in annual emissions of residual tailings from mining and byproducts of industrial lithium extraction has inevitably led to a significant accumulation of waste materials such as lithium slag powder, niobium-tantalum tailings sand, and other mineral powders generated by the high energy consumption characteristics of the lithium battery industry, which urgently need to be consumed and processed. Using auxiliary cementitious materials such as lithium slag powder and mineral powder to partially replace cement in concrete has been proven to be a viable alternative. Based on this, the use of niobium-tantalum tailings sand to partially replace non-renewable river sand aggregate, and lithium slag powder and mineral powder to completely replace cement, is being considered to prepare a solid waste concrete with both cementitious components and aggregates. This concrete can be applied to local ecological restoration, such as slope greening and tailings pond anti-seepage, in response to the "Green Mine Construction Standard" promoted by Jiangxi Province, to achieve the goal of "waste management" and balance resource development with environmental protection. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of the prior art and provide a low-carbon concrete suitable for mining projects. This concrete is low-carbon and environmentally friendly, has high compressive strength, and good fluidity. It can be used as a supplementary material in local mine recycling and excavation projects, achieving tailored waste utilization. While reducing the use of cement clinker and non-renewable aggregate sand, it also reduces the costs of waste disposal and ecological restoration. The present invention also provides a method for preparing the low-carbon concrete suitable for mining projects, which is simple to operate and suitable for large-scale production.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A low-carbon concrete suitable for mining engineering, comprising the following components in parts by weight:

[0007]

[0008] In the present invention, the lithium slag powder is waste lithium slag powder remaining after lithium refining from lepidolite; the particle size of the lithium slag powder ranges from 0.24 to 182 μm. The lithium slag powder has a high amorphous silicate content, with the main crystal forms being gypsum and feldspar minerals, and exhibiting certain hydration properties.

[0009] In the present invention, the third powder is at least one of mineral powder and stone powder.

[0010] The mineral powder is blast furnace ore powder produced by the high energy consumption of the lithium battery industry, which has driven the development of supporting energy sources. The particle size of the mineral powder ranges from 0.31 to 52.5 μm. The mineral powder reacts with the lithium slag powder to hydrate, ensuring the mechanical strength of the concrete in the later stages. Both can serve as a third powder to fill the matrix.

[0011] The average particle size of the stone powder is 2.8-3.4 μm, and the calcium carbonate content in the stone powder is greater than 98 wt%.

[0012] Stone powder has high bonding strength, can fill capillaries, reduce pore connectivity, and have a retarding effect, which is beneficial for pumping.

[0013] In the present invention, the particle size of the silica fume is 0.24-40 μm.

[0014] In the present invention, the silica fume is highly active and can fill the pores inside the concrete, and the active silicon dioxide can undergo a secondary reaction, thereby compacting the internal structure of the concrete.

[0015] The particle size of the niobium-tantalum tailings sand is 0-0.6 mm.

[0016] The river sand particles include first sand particles with a particle size greater than 0.6 mm and less than 1.25 mm, and second sand particles with a particle size of 0 to 0.6 mm.

[0017] In the present invention, the niobium-tantalum tailings can completely or partially replace the second sand particles. When the niobium-tantalum tailings completely replace the second sand particles, the mass ratio of the niobium-tantalum tailings to the first sand particles is preferably 7:2. When the niobium-tantalum tailings partially replace the second sand particles, the mass ratio of the niobium-tantalum tailings, the first sand particles, and the second sand particles is preferably 7:4:7. Using sand particles with this gradation ratio allows for dense packing of the materials, resulting in higher strength.

[0018] In the present invention, the water reducer is a polycarboxylate water reducer with a solid content of 18.2% and an effective water reduction rate of 40%. The content of the water reducer in the concrete is preferably 16 to 19 parts, more preferably 18 parts.

[0019] The present invention also provides a method for preparing low-carbon concrete suitable for mining engineering, which mainly comprises the following steps:

[0020] S1. Weigh each raw material according to the mass ratio of the components;

[0021] S2. The lithium slag powder, silica fume, the third powder, and niobium tantalum tailings, river sand are mixed and stirred to obtain a premix;

[0022] S3. Mix the premix, water reducer and water and stir evenly to prepare a slurry with a water-binder ratio of 0.15 to 0.2.

[0023] In the present invention, the stirring in step S2 is preferably performed in a stirring pot; the stirring speed is preferably 130 to 140 rpm, more preferably 133 to 135 rpm; and the stirring time is 1 to 3 min.

[0024] In the present invention, the mixing and stirring in step S3 includes a first slow stirring, a second slow stirring, a static stirring, and a fast stirring performed in sequence. In the present invention, the speed of the first slow stirring is preferably 130-140 rpm, and the time is preferably 60-90 s; the speed of the second slow stirring is preferably 130-140 rpm, and the time is preferably 90-120 s; the static stirring time is preferably 70-90 s; the speed of the fast stirring is preferably 275-285 rpm, and the time is preferably 80-100 s.

[0025] Compared with the existing technology, the advantages and beneficial effects of the present invention are as follows:

[0026] The present invention adopts lithium slag powder to completely replace cement, constructs a low-carbon ternary cementitious system with silica fume and a third powder, and on this basis uses niobium-tantalum tailings sand from the same place of origin as the lithium slag powder to replace natural river sand, to prepare a low-carbon concrete suitable for mining engineering, which is used as a supplementary material in engineering applications such as excavation. On the one hand, it realizes the green, high-quality and large-scale utilization of industrial tailings, waste slag powder, etc.; on the other hand, it can reduce the use of high-energy-consuming cement and non-renewable aggregates in local mining engineering, thereby reducing the cost of ecological restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Compressive strength test results of concrete prepared in Examples and Comparative Examples;

[0028] Figure 2 The fluidity test results of the concrete slurries prepared in Examples and Comparative Examples are as follows;

[0029] Figure 3 The carbon intensity of the concrete prepared in Examples and Comparative Examples (CO2 emissions per unit strength after 28 days).

[0030] Wherein: A0 is the test data of comparative example 1, A1 is the test data of comparative example 2, and A3 is the test data of comparative example 3; B0 is the test data of embodiment 1, B1 is the test data of embodiment 2, B2 is the test data of embodiment 3, and B3 is the test data of embodiment 4. DETAILED DESCRIPTION

[0031] The present invention provides low-carbon concrete suitable for mining engineering and a preparation method thereof. To clearly and intuitively demonstrate the objectives, technical solutions, and beneficial effects of the present invention, specific embodiments are described in detail below. It should be understood that the examples cited are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0032] In the specific embodiments of the present invention, unless otherwise specified, all components are commercially available products well known to those skilled in the art.

[0033] In this specific embodiment, a low-carbon concrete suitable for mining engineering contains the following components in parts by weight:

[0034]

[0035] Wherein: the lithium slag powder is the lithium slag powder produced after lithium is refined from lepidolite ore in Jiangxi Province, and the selected particle size is 0.24-182 μm.

[0036] The three powders are at least one of mineral powder and stone powder. The mineral powder is blast furnace mineral powder produced in Yichun, Jiangxi Province, which is driven by the high energy consumption of the lithium battery industry and the supporting energy construction. The particle size is 0.31-52.5 μm. The average particle size of the stone powder is 2.8-3.4 μm, and the calcium carbonate content of the stone powder is greater than 98% by weight.

[0037] The particle size of silica fume is 0.24 to 40 μm. The particle size of niobium-tantalum tailings sand is 0 to 0.6 mm.

[0038] The river sand particles include first sand particles with a particle size greater than 0.6 mm and less than 1.25 mm, and second sand particles with a particle size of 0 to 0.6 mm. In a specific embodiment, the niobium-tantalum tailings can completely or partially replace the second sand particles. When the tantalum tailings completely replace the second sand particles, the mass ratio of the niobium-tantalum tailings to the first sand particles is 7:2. When the niobium-tantalum tailings partially replace the second sand particles, the mass ratio of the niobium-tantalum tailings to the first sand particles is 7:4:7.

[0039] In the present invention, the water reducer is a polycarboxylate water reducer with a solid content of 18.2% and an effective water reduction rate of 40%. The content of the water reducer in the concrete is preferably 16 to 19 parts, and 18 parts is preferred in the embodiments.

[0040] This specific embodiment also provides a method for preparing low-carbon concrete suitable for mining engineering, which mainly includes the following steps:

[0041] S1. Weigh each raw material according to the mass ratio of the components;

[0042] S2. The lithium slag powder, silica fume, the third powder, and niobium tantalum tailings, river sand mixed, stirred at a speed of 130rpm for 1min, stirred to obtain a premix;

[0043] S3. Mix the premix, water reducer and water, stir at 130 rpm for 60 seconds, and after forming a slurry, stir at 130 rpm for 90 seconds, let it stand for 70 seconds, and stir at 275 rpm for 80 seconds. Stir evenly to obtain the mineral powder slurry.

[0044] The present invention provides four embodiments and three comparative examples of different components, and the comparison shows the improvement of the performance of the concrete prepared by the embodiments of the present invention. The weight of each component is shown in Table 1.

[0045] Table 1 Comparative Examples and Examples Raw Material Proportions (Parts)

[0046]

[0047] Performance Testing

[0048] 1. Compressive strength test

[0049] According to the data in Table 1, and according to the above-mentioned method for preparing low-carbon concrete suitable for mining engineering, the slurries of Examples 1-4 and Comparative Examples 1-32 were prepared, and the obtained mortars were poured into molds, compacted on a vibration table, and then the surface was scraped flat and coated, and then placed at room temperature for 24 hours before demolding;

[0050] The demolded test blocks were placed in a standard curing room for oxidation, wherein the temperature of the curing room was 20±2° C. and the relative humidity was ≥95%. The curing ages were 3 days, 7 days, and 28 days, respectively, to obtain the concrete suitable for mining engineering.

[0051] The concrete suitable for mining engineering prepared above was prepared into test pieces with a size of 40 mm × 40 mm × 160 mm, and the compressive strength was tested according to the "Test method for strength of cement mortar (ISO method)" (GB / T 17671-1999); the test results are shown in Table 2 and Figure 1 shown.

[0052] Table 2 Mechanical properties test results

[0053]

[0054] From Table 2 and Figure 1It can be seen that the present invention uses niobium-tantalum tailings sand to partially replace sand particles, and the resulting concrete suitable for mining engineering can reduce the use of non-renewable aggregates while ensuring compressive strength.

[0055] 2. Flowability test

[0056] The cement mortars obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were tested for fluidity according to the standard specification of EN 1015-3;

[0057] The test process includes: using a truncated cone mold (60mm height, 70mm top diameter, 100mm bottom diameter) to measure the diffusion flow of the slurry: filling the mold with slurry and lifting the cone straight up to allow the slurry to flow freely without shaking; calculating the diffusion flow by averaging the two perpendicular diameters, with an error of no more than 2%, and taking the average as the flowability data; the flow test is carried out at room temperature of 20±1℃;

[0058] The test results obtained are as follows Figure 2 As shown, from Figure 2 It can be seen that the changes in the third powder and niobium-tantalum tailings in the embodiment have little effect on the fluidity of the sample, and still maintain a high fluidity, meeting the requirements of long-distance high-pressure pumping (180-220 mm).

[0059] 3. Carbon emissions testing

[0060] The concrete obtained in Examples 1 to 4 and Comparative Examples 1 to 3 was tested and evaluated for global warming potential (GWP) using SimaPro 7.1 according to European standards EN ISO 14040 and EN ISO 14044. Carbon emission analysis was performed on the raw materials of Examples 1 to 4 and Comparative Examples 1 to 3 using the BEES method, and the Ci values ​​of Examples 1 to 4 and Comparative Examples 1 to 3 were calculated based on the 28d strength. The test results are shown in Tables 3 and Figure 3 shown.

[0061] Table 3 Environmental test results

[0062] GWP Ci Example 1 68.6 0.826506 Example 2 74.9 0.948101 Example 3 78.2 0.878652 Example 4 76.7 0.881609 Comparative Example 1 81.6 0.937931 Comparative Example 2 78.2 0.898851 Comparative Example 3 140 1.296296

[0063] From Table 3 and Figure 3 It can be seen that using lithium slag powder instead of cement and niobium tantalum sand instead of river sand will reduce the carbon dioxide emissions per unit strength of the high-strength solid waste concrete of the present invention, indicating that this method can effectively reduce the carbon emissions of concrete and its production cost while maintaining high strength.

Claims

1. A low-carbon concrete suitable for mining engineering, characterized in that: Contains the following components in parts by mass:

2. The low-carbon concrete suitable for mining engineering according to claim 1, characterized in that: The lithium slag powder is waste lithium slag powder remaining after lithium is refined from lepidolite; the particle size of the lithium slag powder is 0.24 to 182 μm.

3. The low-carbon concrete suitable for mining engineering according to claim 1, characterized in that: The third powder is at least one of mineral powder and stone powder.

4. The low-carbon concrete suitable for mining engineering according to claim 3, characterized in that: The mineral powder is blast furnace mineral powder produced by the high energy consumption characteristics of the lithium battery industry, which stimulates the construction of supporting energy. The particle size of the mineral powder is 0.31-52.5 μm; the average particle size of the stone powder is 2.8-3.4 μm, and the calcium carbonate content in the stone powder is greater than 98wt%.

5. The low-carbon concrete suitable for mining engineering according to claim 1, characterized in that: The particle size of the silica fume is 0.24-40 μm.

6. The low-carbon concrete suitable for mining engineering according to claim 1, characterized in that The particle size of the niobium-tantalum tailings sand is 0-0.6 mm.

7. The low-carbon concrete suitable for mining engineering according to claim 1, characterized in that The river sand particles include first sand particles with a particle size of 0.6 to 1.25 mm, and second sand particles with a particle size of 0 to 0.6 mm.

8. The low-carbon concrete suitable for mining engineering according to claim 1, characterized in that: The water reducer is a polycarboxylic acid water reducer with a solid content of 18.2% and an effective water reduction rate of 40%.

9. A method for preparing low-carbon concrete suitable for mining engineering according to any one of claims 1 to 8, characterized in that The following steps are involved: S1. Weigh each raw material according to the mass ratio of the components; S2. The lithium slag powder, silica fume, the third powder, and niobium tantalum tailings, river sand are mixed and stirred to obtain a premix; S3. Mix the premix, water reducer and water until evenly mixed.

10. A method for preparing low-carbon concrete suitable for mining engineering according to claim 9, characterized in that The specific steps include: S1. Weigh each raw material according to the mass ratio of the components; S2. The lithium slag powder, silica fume, the third powder, and niobium tantalum tailings, river sand mixed, stirred at a speed of 130 to 140 rpm for 1min1 to 3min, stirred to obtain a premix; S3. Mix the premix, water reducer and water, stir at a speed of 130-140 rpm for 60-90 seconds, and after forming a slurry, continue stirring for 90-120 seconds, let it stand for 70-90 seconds, and stir at a speed of 275-285 for 80-100 seconds to obtain the mineral powder slurry.

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