Mine tailing self-leveling mortar and preparation method thereof

Abstract

The invention discloses mine tailing self-leveling mortar and a preparation method thereof, and relates to the technical field of ultraviolet aging resistant self-leveling mortar. The mine tailing self-leveling mortar is prepared from the following raw materials in parts by mass: 20 to 35 parts of cementing material, 40 to 60 parts of mine tailing aggregate, 5 to 15 parts of limestone powder, 0.5 to 2 parts of reinforced fiber, 0.3 to 1.5 parts of water reducing agent, 0.1 to 0.5 part of defoaming agent, 0.05 to 0.3 part of water-retaining agent, 0.05 to 0.2 part of retarder, 1 to 2 parts of anti-ultraviolet agent and 15 to 20 parts of water. The traditional natural aggregate is replaced by the mine tailing aggregate, so that the occupied space and environmental pollution caused by tailing stockpiling are effectively reduced, meanwhile, the natural stone mining requirement is reduced, and the resource recycling is realized.

Description

Technical Field

[0001] The invention relates to the technical field of ultraviolet aging-resistant self-leveling mortar, and in particular to a mine tailings self-leveling mortar and a preparation method thereof. Background Art

[0002] In the fields of construction and floor leveling, traditional self-leveling mortars present numerous pressing challenges. For one thing, conventional products often use aggregates processed from natural stone as their primary component, which not only accelerates the depletion of natural stone resources but also leads to high costs due to the complex mining and processing process. Furthermore, from a performance perspective, the durability of traditional self-leveling mortars is unsatisfactory. For example, in outdoor settings exposed to long-term UV radiation, their internal structure is easily damaged, resulting in cracking and flaking, which significantly shortens their service life and increases the cost and frequency of repairs.

[0003] At the same time, the challenge of handling mine tailings has become increasingly prominent. With the continued expansion of mining operations, vast quantities of tailings are generated. These tailings are often simply stored, occupying significant land resources. Under the influence of natural factors like rain, wind, and sunlight, they can easily cause serious environmental problems such as water and soil pollution. While the industry has recognized the feasibility of using tailings in building material production, research and development and application in self-leveling mortar are still in their infancy, lacking a mature, systematic technical solution.

[0004] In summary, the market currently urgently needs a self-leveling mortar that can effectively utilize mine tailings and reduce environmental burden, and has excellent durability such as anti-ultraviolet aging performance, so as to break through the multiple bottlenecks of traditional products in terms of resources, environment and performance. Summary of the Invention

[0005] The present invention provides a mine tailings self-leveling mortar and a preparation method thereof, aiming to utilize mine tailings to replace natural aggregates to solve the problem of tailings storage pollution. At the same time, by adding an anti-ultraviolet agent, the durability of the material is significantly improved to adapt to the needs of complex outdoor environments.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a mine tailings self-leveling mortar, composed of the following raw materials in parts by weight: 20-35 parts of a cementitious material, 40-60 parts of a mine tailings aggregate, 5-15 parts of limestone powder, 0.5-2 parts of a reinforcing fiber, 0.3-1.5 parts of a water reducer, 0.1-0.5 parts of a defoamer, 0.05-0.3 parts of a water retaining agent, 0.05-0.2 parts of a retarder, 1-2 parts of an anti-ultraviolet agent, and 15-20 parts of water; The anti-ultraviolet agent is a compound represented by Formula 1: Formula 1; R1 in Formula 1 is a substituent, and R1 is selected from: an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an aryl group having 6 to 10 carbon atoms.

[0007] Furthermore, the cementitious material is at least one of silicate cement and sulphoaluminate cement.

[0008] Furthermore, the mine tailings aggregate is one of iron ore tailings, copper ore tailings or gold ore tailings, and has a fineness modulus of 1.8-2.5.

[0009] Furthermore, the particle size of the limestone powder is ≤30 μm.

[0010] Furthermore, the reinforcing fiber is one of polypropylene fiber and polyvinyl alcohol fiber, and has a length of 3-12 mm.

[0011] Furthermore, the water reducer is a naphthalene-based water reducer.

[0012] Furthermore, the defoaming agent is: polyether modified silicone defoaming agent DT-650.

[0013] Furthermore, the water-retaining agent is hydroxypropyl methylcellulose ether.

[0014] Furthermore, the retarder is at least one of sodium gluconate, citric acid or sodium pyrophosphate.

[0015] Furthermore, the R1 is methyl, ethyl, tert-butyl, phenyl, methoxy, or ethoxy.

[0016] Furthermore, the anti-ultraviolet agent is any one of the compounds shown in the following structures: ; .

[0017] A method for preparing mine tailings self-leveling mortar comprises the following steps: S1. The cementitious material, mine tailings aggregate, reinforcing fiber, water-retaining agent and retarder were added to the mixer and mixed at 300~500rpm for 3-5 minutes to obtain a premixed dry material; S2. The limestone powder, water reducer and UV inhibitor were added to the premixed dry material and mixing was continued for 8 to 12 minutes to obtain a mixed dry material; S3. Add the water to the mixed dry material in portions, adjust the mixer to 800-1000 rpm and mix for 5-8 minutes, add a defoamer, and mix at 400-600 rpm for 5-15 minutes to obtain a mine tailings self-leveling mortar.

[0018] Furthermore, the mine tailings aggregate in S1 is dried in advance at 105±5° C. to a moisture content of ≤0.5%.

[0019] Furthermore, the water in S3 is added twice, 70% of the total amount is added for the first time and mixed for 3 minutes, and the remaining 30% is added during stirring.

[0020] Furthermore, the resulting slurry is allowed to stand and defoam for 10 to 15 minutes after pouring, and the compressive strength is ≥25 MPa after curing at 20±2°C and relative humidity ≥95% for 7 days.

[0021] Furthermore, the mine tailings self-leveling mortar can be used as a lightweight building material.

[0022] Furthermore, the mine tailings self-leveling mortar can be used to prepare outer protective shells of energy-saving boilers and other boilers and auxiliary equipment.

[0023] The molecular structure of the UV inhibitor described in this invention can be divided into three parts: a hydroxyl active hydrogen, a heterocyclic conjugated structure, and a long alkyl chain. The hydroxyl active hydrogen provides active hydrogen atoms (H·). When ultraviolet radiation or environmental factors trigger a free radical chain reaction in the mortar, the UV inhibitor acts as a hydrogen donor, reacting promptly with these highly reactive free radicals to generate relatively stable free radical products, thereby terminating the chain oxidation reaction. The heterocyclic conjugated structure possesses strong UV absorption, particularly in the ultraviolet (UV) region (such as the UV-A and UV-B bands). After absorbing UV photon energy, the hydrogen bond network and conjugated system within the structure rapidly release the absorbed energy back into the environment as harmless heat. This UV absorption and energy conversion process effectively forms a "molecular barrier" within the mortar, significantly reducing the chance of UV rays penetrating the polymer structure and some inorganic surfaces, thereby preventing photodegradation. The long alkyl chain enhances the compound's compatibility with the mortar matrix by regulating its solubility and dispersibility, maximizing its functionality.

[0024] The present invention uses a three-level synergistic mechanism of material design-molecular customization-process coupling to simultaneously solve the three major technical problems of natural aggregate resource consumption, tailings environmental pollution, and insufficient durability caused by ultraviolet aging. Specifically: among the main material components, mine tailings aggregate replaces natural aggregate and consumes tailings, and its trace metal components can catalyze hydration; the cementitious material provides adhesion, which can compensate for the low activity of tailings and solidify heavy metals in a high-alkaline environment; ultrafine limestone powder fills the gaps and improves rheological properties. The three work together to form a tightly packed structure. Functional additives achieve improvements in durability: the hydroxyl active hydrogen of the anti-ultraviolet agent terminates the free radical chain reaction, the heterocyclic conjugated structure absorbs 280-400nm ultraviolet rays and converts them into heat energy, and the long alkyl chain adjusts the dispersibility to form a molecular-level ultraviolet barrier; the reinforcing fiber bridges the cracks to inhibit shrinkage cracking caused by ultraviolet rays; the retarder controls the hydration rate to reduce temperature cracks; the water-retaining agent forms a water film to reduce the risk of ultraviolet erosion on the surface of the cementitious material. The process components and procedures ensure synergistic effectiveness: the water-reducing agent reduces the water-binder ratio to improve density, and its alkyl chain and UV inhibitor synergistically improve the rheological properties of the slurry; the defoamer eliminates pore defects; combined with tailings pretreatment, step-by-step mixing process and curing, they jointly promote a high-strength matrix.

[0025] Compared with the prior art, the present invention has the following beneficial effects: 1. Efficient resource utilization and environmentally friendly trends: By using mine tailings aggregates to replace traditional natural aggregates, the land occupied by tailings storage and environmental pollution can be effectively reduced, while the demand for natural stone mining can be reduced, thus achieving resource recycling.

[0026] 2. Durability improvement trend: Adding anti-UV agents with customized molecular structures to form a "molecular barrier" can significantly inhibit free radical reactions and photodegradation caused by ultraviolet rays, delay the cracking and peeling of mortar, and improve long-term service life.

[0027] 3. Comprehensive performance optimization trend: The synergistic effect of multiple components (such as reinforcing fibers inhibiting shrinkage cracks, retarders optimizing hydration rate, and water-retaining agents reducing the risk of surface erosion) enhances the strength and stability of mortar, and simultaneously improves rheological properties and construction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the nuclear magnetic spectrum of the anti-ultraviolet agent 1 of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] A mine tailings self-leveling mortar is composed of the following raw materials in parts by weight: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 parts of cementitious materials; 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 parts of mine tailings aggregate; 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts of limestone powder; Reinforcement fiber 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 parts; Water reducer 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 parts; Defoaming agent 0.1, 0.2, 0.3, 0.4, 0.5 parts; Water retaining agent 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3 parts; Retarder 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20 parts; 1 or 2 parts of UV inhibitor; 15, 16, 17, 18, 19, 20 parts of water.

[0031] Preparation Example 1 Synthesis of UV-resistant agent 1: The synthesis of UV-resistant agent 1 is prepared by two-step chemical reaction, specifically: first step: ; 20 g of starting material 1 and 10.49 g of starting material 2 were added to a flask containing 250 ml of DMSO, and the resulting reaction mixture was stirred for 5 minutes. After replacing the air with nitrogen, 10.55 g of potassium tert-butoxide was added under a continuous nitrogen atmosphere. The system temperature was then raised to 65°C and the reaction was allowed to proceed for 8 hours. The reaction was monitored by HPLC. Upon completion, the mixture was poured into 0°C water and stirred for 15 minutes. Ethyl acetate was then added for extraction, and the organic phase was retained and dried. The dried powder was purified by column chromatography (silica gel, eluent: petroleum ether / ethyl acetate) and dried again to yield 21.56 g of intermediate 1. Mass spectrum: MS+1: 531.

[0032] Step 2: ; Under a nitrogen atmosphere, 21.56 g of intermediate 1, 14.26 g of raw material 3, 0.4 g of tri-tert-butyl phosphine, 0.14 g of palladium on carbon, 9.12 g of potassium tert-butoxide, and 250 ml of toluene were added to the reaction system, and the temperature was raised to 120°C and refluxed for 12 hours. After the reaction, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth. After the filtrate was cooled to room temperature, it was washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. After the organic phases were combined, the organic phases were dried over anhydrous magnesium sulfate, filtered, and dried by spin drying. The dried powder was purified by column chromatography (silica gel, eluent: petroleum ether / ethyl acetate) and dried again by spin drying to obtain 25.20 g of UV inhibitor 1. Mass spectrum MS+1: 769. NMR: see Figure 1 .

[0033] Preparation Example 2-Preparation Example 6 In Preparation Examples 2-6, UV-blocking agents 2-6 were prepared sequentially, following the same preparation method as in Preparation Example 1, except that raw material 2 was replaced. The specific structures of raw material 2, UV-blocking agents 2-6, and mass spectrometry (MS+1) data are shown in Table 1.

[0034] Table 1.

[0035] Example 1

[0036] Preparation of a mine tailings self-leveling mortar: 1. Raw material ratio: Cementitious material: 30 parts, selected from: PO 42.5 Portland cement, purchased from: Tangshan Tianlu Cement Co., Ltd.; Mine tailings aggregate: 50 parts, selected from: iron ore tailings, fineness modulus 2.0, purchased from: Fujian Makeng Mining Co., Ltd., pre-treated by drying at 105℃ to a moisture content of ≤0.5%; Limestone powder: 10 parts, selected from: particle size ≤ 30 μm (D90 value), purchased from: Wuhan Deyi Environmental Protection New Materials Co., Ltd.; Reinforcement fiber: 1.0 part, selected from: polypropylene fiber, average length 6 mm, purchased from: Shandong Luxian Building Materials Technology Co., Ltd.; Water reducer: 0.8 parts, selected from: naphthalene water reducer, SBTJM ® -B naphthalene-based high-efficiency water reducer, purchased from: Jiangsu Subote New Materials Co., Ltd.; Defoaming agent: 0.3 parts, selected from: polyether modified silicone defoaming agent DT-650, purchased from: Foshan Nanhai Datian Chemical Co., Ltd.; Water-retaining agent: 0.15 parts, selected from: hydroxypropyl methylcellulose ether, purchased from: Zhejiang Haishen New Materials Co., Ltd.; Retarder: 0.1 part, selected from: sodium gluconate, purity ≥99%, purchased from: Shandong Beida Hi-Tech Huatai Pharmaceutical Co., Ltd.; Anti-ultraviolet agent: 1.5 parts, selected from: Anti-ultraviolet agent 1, prepared in Preparation Example 1; Water: tap water, 18 parts.

[0037] 2. Preparation method: S1. The dried iron ore tailings, Portland cement, polypropylene fiber, hydroxypropyl methylcellulose ether and sodium gluconate were added to a planetary mixer and mixed at 400 rpm for 4 minutes to obtain a premixed dry material; S2 was added to the premixed dry material limestone powder, naphthalene water reducer and UV inhibitor 1, continued to mix at 400rpm speed for 10 minutes, the mixing process temperature was controlled ≤ 30 ℃ to obtain a mixed dry material; S3. Transfer the dry mix to a blender and add water in portions. Initially, add 70% (12.6 parts) of the total water. Adjust the speed to 500 rpm and mix for 3 minutes. Then, add the remaining 30% (5.4 parts) of water while continuing to stir. Add defoamer DT-650 and mix at 500 rpm for 10 minutes to obtain a uniform, bubble-free self-leveling mortar for mine tailings.

[0038] Example 2-Example 6 A self-leveling mortar for mine tailings is prepared by referring to the preparation method of Example 1, except that the anti-ultraviolet agent therein is replaced with anti-ultraviolet agent 2 to anti-ultraviolet agent 6 in sequence, and the rest remains the same as Example 1.

[0039] In order to better highlight the technical effects of the present invention, the present invention sets the following comparative examples: Comparative Example 1 A preparation method of mine tailings self-leveling mortar, referring to the preparation method of Example 1, wherein the anti-ultraviolet agent is replaced with the ultraviolet absorber UV-1577 ( ), the rest remains the same as in Example 1.

[0040] Comparative Example 2 A self-leveling mortar for mine tailings was prepared by referring to the preparation method of Example 1, except that the anti-ultraviolet agent was replaced with the comparative compound 1 in sequence, and the rest remained the same as in Example 1.

[0041] Comparative compound 1: .

[0042] Comparative Example 3 A self-leveling mortar for mine tailings was prepared by referring to the preparation method of Example 1, except that the anti-ultraviolet agent was replaced with the comparative compound 2 in sequence, and the rest remained the same as in Example 1.

[0043] Comparative compound 2: .

[0044] Comparative Example 4 A preparation method of mine tailings self-leveling mortar, referring to the preparation method of Example 1, wherein the anti-ultraviolet agent is replaced with ultraviolet absorber-928 ( ), the rest remains the same as in Example 1.

[0045] Comparative Example 5 A self-leveling mortar for mine tailings was prepared by referring to the preparation method of Example 1, except that the water reducing agent was not added, and the rest of the preparation method remained the same as that of Example 1.

[0046] Comparative Example 6 A self-leveling mortar for mine tailings was prepared by referring to the preparation method of Example 1, except that the water retaining agent was not added, and the rest of the preparation method remained the same as that of Example 1.

[0047] Comparative Example 7 A self-leveling mortar for mine tailings was prepared by referring to the preparation method of Example 1, except that the reinforcing fiber was not added, and the rest of the preparation method remained the same as that of Example 1.

[0048] Performance testing: The flexural strength (MPa) and compressive strength (MPa) of the mine tailings self-leveling mortar prepared in the above examples and comparative examples were tested according to the test method of JC / T 985-2017 "Cement-based self-leveling mortar for floor use" after natural standing for 28 days. The data are shown in Table 2.

[0049] According to ASTM G154 "Ultraviolet Aging Test General Standard", a mine tailings self-leveling mortar prepared in the above embodiment and comparative example was cast into a standard specimen (such as 40 mm × 40 mm × 160 mm), cured under standard conditions (20 ± 2 ° C, RH ≥ 95%) for 7 days, and naturally allowed to stand for 28 days. The specimen was then placed in a UV aging test chamber with an ultraviolet band of UVA-340 and an irradiation intensity of 0.76 W / m 2 The aging cycle was 1000h, with 8 hours of UV irradiation and 4 hours of condensation to simulate the real environment. The cracking, peeling or discoloration of the specimens after aging were observed. The flexural strength and compressive strength after aging were measured (based on the JC / T985-2017 method), and the strength loss rate (%) was calculated.

[0050] Table 2.

[0051]

[0052] The Example group exhibited a high stability trend in 28-day flexural and compressive strength, and the strength loss rate after aging was significantly lower than that of the Comparative Example group, reflecting its excellent resistance to UV aging and durability. In contrast, the Comparative Example group (including those using alternative UV absorbers or omitting key ingredients such as water reducers, water retention agents, or reinforcing fibers) showed an overall lower strength trend and a significantly increased aging loss rate. This increase was particularly pronounced when using a standard UV absorber or when the ingredient was omitted, highlighting the role of the UV inhibitor of the present invention in optimizing the long-term performance of the mortar when used in conjunction with other components. This demonstrates that the formulation of the present invention effectively suppresses UV-induced degradation through material selection and additive integration.

[0053] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A mine tailings self-leveling mortar, characterized in that: The invention is composed of the following raw materials in parts by mass: 20-35 parts of cementitious material, 40-60 parts of mine tailings aggregate, 5-15 parts of limestone powder, 0.5-2 parts of reinforcing fiber, 0.3-1.5 parts of water reducing agent, 0.1-0.5 parts of defoaming agent, 0.05-0.3 parts of water retaining agent, 0.05-0.2 parts of retarder, 1-2 parts of UV inhibitor and 15-20 parts of water; The anti-ultraviolet agent is a compound represented by Formula 1: Formula 1; R1 in Formula 1 is a substituent, and R1 is selected from: an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an aryl group having 6 to 10 carbon atoms.

2. The mine tailings self-leveling mortar according to claim 1, characterized in that: The cementitious material is at least one of silicate cement and sulphoaluminate cement; The mine tailings aggregate is one of iron ore tailings, copper ore tailings or gold ore tailings, and has a fineness modulus of 1.8-2.

5.

3. The mine tailings self-leveling mortar according to claim 1, characterized in that: The particle size of the limestone powder is ≤30 μm.

4. The mine tailings self-leveling mortar according to claim 1, characterized in that: The reinforcing fiber is one of polypropylene fiber and polyvinyl alcohol fiber, and has a length of 3-12 mm.

5. The mine tailings self-leveling mortar according to claim 1, characterized in that: The water reducer is a naphthalene-based water reducer; The defoaming agent is: polyether modified silicone defoaming agent DT-650; The water-retaining agent is hydroxypropyl methylcellulose ether.

6. The mine tailings self-leveling mortar according to claim 1, characterized in that: The retarder is at least one of sodium gluconate, citric acid or sodium pyrophosphate.

7. The mine tailings self-leveling mortar according to claim 1, characterized in that: The anti-ultraviolet agent is any one of the compounds shown in the following structures: ； 。 8. A method for preparing a mine tailings self-leveling mortar according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. The cementitious material, mine tailings aggregate, reinforcing fiber, water-retaining agent and retarder were added to the mixer and mixed at 300~500rpm for 3-5 minutes to obtain a premixed dry material; S2. The limestone powder, water reducer and UV inhibitor were added to the premixed dry material and mixing was continued for 8 to 12 minutes to obtain a mixed dry material; S3. Add the water to the mixed dry material in portions, adjust the mixer to 800-1000 rpm and mix for 5-8 minutes, add a defoamer, and mix at 400-600 rpm for 5-15 minutes to obtain a mine tailings self-leveling mortar.

9. The method for preparing a mine tailings self-leveling mortar according to claim 8, characterized in that: The mine tailings aggregate in S1 is dried in advance at 105±5° C. to a moisture content of ≤0.5%.

10. The method for preparing a mine tailings self-leveling mortar according to claim 8, characterized in that: The water in S3 was added twice, 70% of the total amount was added for the first time and mixed for 3 minutes, and the remaining 30% was added during stirring.

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