Mine tailings self-leveling mortar and preparation method thereof

Abstract

The application discloses a mine tailing self-leveling mortar and a preparation method thereof, and relates to the technical field of self-leveling mortars with ultraviolet aging resistance. The mine tailing self-leveling mortar is composed of raw materials in the following proportions by mass: cementing material 20-35 parts, mine tailing aggregate 40-60 parts, limestone powder 5-15 parts, reinforcing fiber 0.5-2 parts, water reducing agent 0.3-1.5 parts, defoaming agent 0.1-0.5 parts, water retaining agent 0.05-0.3 parts, retarder 0.05-0.2 parts, ultraviolet resistant agent 1-2 parts and water 15-20 parts. The mine tailing aggregate is used to replace traditional natural aggregate, so that the land occupation and environmental pollution caused by tailing storage are effectively reduced, the demand for natural stone mining is lowered, and resource recycling is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of self-leveling mortar with ultraviolet aging resistance, and particularly relates to a mine tailings self-leveling mortar and a preparation method thereof. BACKGROUND

[0002] In the field of building construction and ground leveling, the traditional self-leveling mortar has many problems to be solved. On the one hand, the conventional product is mainly composed of aggregate processed from natural stone, which not only accelerates the depletion of natural stone resources, but also leads to high cost due to the complex mining and processing process. On the other hand, from the performance point of view, the durability of the traditional self-leveling mortar is not satisfactory. For example, in the case of ultraviolet aging resistance, the internal structure is easily damaged in the outdoor scene subjected to long-term ultraviolet radiation, and cracking, peeling and other phenomena occur, which greatly shortens the service life and increases the maintenance cost and frequency.

[0003] At the same time, the problem of mine tailings treatment is increasingly prominent. With the continuous expansion of mining scale, a large amount of tailings is generated. These tailings are mostly simply stacked, occupying a large amount of land resources, and under the action of natural factors such as rainwater erosion, wind and sunlight, they are extremely easy to cause serious environmental problems such as water pollution and soil pollution. Although the industry has realized the feasibility of using tailings for building material production, in the field of self-leveling mortar, relevant research and application are still in the initial stage, and there is a lack of mature and systematic technical solution.

[0004] In summary, there is an urgent need in the market for a self-leveling mortar that can effectively utilize mine tailings, reduce environmental burden, and has excellent ultraviolet aging resistance and other durability characteristics, to break through the multiple bottlenecks of traditional products in resources, environment and performance. SUMMARY

[0005] The present application provides a mine tailings self-leveling mortar and a preparation method thereof, aiming to replace natural aggregate with mine tailings to solve the problem of tailings stacking pollution, and significantly improve the durability of the material by adding an ultraviolet resistant agent to adapt to the needs of complex outdoor environments.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a mine tailings self-leveling mortar is composed of the following raw materials in mass parts: cementing material 20-35 parts, mine tailings aggregate 40-60 parts, limestone powder 5-15 parts, reinforcing fiber 0.5-2 parts, water reducing agent 0.3-1.5 parts, defoaming agent 0.1-0.5 parts, water retaining agent 0.05-0.3 parts, retarder 0.05-0.2 parts, ultraviolet resistant agent 1-2 parts, and water 15-20 parts.

[0007] The ultraviolet resistant agent is a compound as shown in formula 1:

[0008] Formula 1;

[0009] R1 in the Formula 1 is a substituent, and R1 is selected from the group consisting of alkyl with carbon atoms number 1-5, alkoxy with carbon atoms number 1-5, aryl with carbon atoms number 6-10.

[0010] Further, the cementitious material is at least one of Portland cement and sulphoaluminate cement.

[0011] Further, the mine tailings aggregate is one of iron mine tailings, copper mine tailings or gold mine tailings, and fineness modulus is 1.8-2.5.

[0012] Further, the limestone powder has a particle size ≤30 μm.

[0013] Further, the reinforcing fiber is one of polypropylene fiber and polyvinyl alcohol fiber, and the length is 3-12 mm.

[0014] Further, the water reducing agent is a naphthalene series water reducing agent.

[0015] Further, the defoaming agent is polyether modified silicone defoaming agent DT-650.

[0016] Further, the water retaining agent is hydroxypropyl methyl cellulose ether.

[0017] Further, the retarder is at least one of sodium gluconate, citric acid or sodium pyrophosphate.

[0018] Further, R1 is methyl, ethyl, tert-butyl, phenyl, methoxy, ethoxy.

[0019] Further, the anti-ultraviolet agent is any one of the compounds shown in the following structures:

[0020] ;

[0021] .

[0022] A preparation method of a mine tailings self-leveling mortar comprises the following steps:

[0023] S1. The cementitious material, mine tailings aggregate, reinforcing fiber, water retaining agent and retarder are added into a mixing machine, and mixed at 300-500 rpm for 3-5 minutes to obtain a premixed dry material;

[0024] S2. The limestone powder, water reducing agent and anti-ultraviolet agent are added into the premixed dry material, and continue to mix for 8-12 minutes to obtain a mixed dry material;

[0025] S3. The water is added to the mixed dry materials in portions, the mixer is adjusted to 800-1000 rpm for 5-8 minutes, an antifoaming agent is added, and mixing is carried out at 400-600 rpm for 5-15 minutes to obtain a mine tailings self-leveling mortar.

[0026] Further, the mine tailings aggregate in S1 is dried in advance at 105±5 DEG C to a water content of ≤0.5%.

[0027] Further, the water is added in two portions in S3, 70% of the total amount is added and mixed for 3 minutes, and the remaining 30% is added while mixing.

[0028] Further, the obtained slurry is poured and allowed to stand for 10-15 minutes for defoaming, and the compressive strength is ≥25 MPa after curing at 20±2 DEG C and a relative humidity of ≥95% for 7 days.

[0029] Further, the mine tailings self-leveling mortar can be used as a light building material.

[0030] Further, the mine tailings self-leveling mortar can be used for preparing an outer protective shell of an energy-saving boiler and auxiliary equipment.

[0031] The molecular structure of the anti-ultraviolet agent can be divided into three parts: hydroxyl active hydrogen, heterocyclic conjugated structure and long alkyl chain. The hydroxyl active hydrogen provides active hydrogen atoms (H·), when ultraviolet irradiation or environmental factors induce free radical chain reactions in the mortar, the anti-ultraviolet agent can act as a hydrogen donor, and reacts with these highly active free radicals in time to generate relatively stable free radical products, thereby terminating the chain oxidation reaction. The heterocyclic conjugated structure has strong ultraviolet absorption capacity, especially in the ultraviolet light region (such as UV-A and UV-B bands), when the molecule absorbs ultraviolet photon energy, the hydrogen bond network and conjugated system in its structure can promote the absorbed energy to be rapidly released back to the environment in the form of harmless heat energy, and the ultraviolet absorption and energy conversion process is equivalent to forming a layer of "molecular barrier" inside the mortar, which significantly reduces the probability of ultraviolet penetrating the polymer structure inside the mortar and the surface of part of inorganic materials, thereby preventing photodegradation reaction. The long alkyl chain adjusts the solubility and dispersibility of the compound to improve the compatibility with the mortar matrix, so that it can maximize its function.

[0032] The present application synchronously solves three technical problems of natural aggregate resource consumption, tailings environmental pollution and durability deficiency caused by ultraviolet aging through a three-level synergistic mechanism of material design-molecular customization-process coupling. Specifically, in the main material component, the mine tailings aggregate replaces the natural aggregate and absorbs the tailings, and the trace metal components can catalyze hydration; the cementing material provides bonding force, can compensate for the low activity of the tailings and solidify heavy metals in the high alkali environment; the ultra-fine limestone powder fills the gap, improves the rheological property, and the three form a close-packed structure. Functional additives realize the progress of durability: the hydroxyl active hydrogen of the anti-ultraviolet agent terminates the free radical chain reaction, the heterocyclic conjugated structure absorbs 280-400 nm ultraviolet rays and converts heat energy, the long alkyl chain adjusts the dispersibility, forming a molecular level ultraviolet barrier; the reinforcing fiber bridges the cracks to inhibit the shrinkage cracking induced by ultraviolet rays; the retarder controls the hydration rate to reduce the temperature cracks; the water retaining agent forms a water film to reduce the risk of ultraviolet erosion on the surface of the cementing material. Process components and flow guarantee synergistic effect: water reducing agent reduces water-binder ratio to improve density, its alkyl chain cooperates with anti-ultraviolet agent to improve the rheological property of the slurry; defoaming agent eliminates pore defects; combined with tailings pretreatment, step-by-step mixing process and curing, it together promotes the high-strength matrix.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] 1. Resource efficient utilization and environmental friendly trend: By using mine tailings aggregate to replace traditional natural aggregate, the tailings storage land occupation and environmental pollution are effectively reduced, and the demand for natural stone mining is also reduced, realizing resource recycling.

[0035] 2. Durability improvement trend: The anti-ultraviolet agent with customized molecular structure is added to form a "molecular barrier", which significantly inhibits the free radical reaction and photodegradation induced by ultraviolet rays, delays the cracking and peeling of the mortar, and improves the long-term service life.

[0036] 3. Comprehensive performance optimization trend: Multi-component synergistic effect (such as reinforcing fiber inhibiting shrinkage cracking, retarder optimizing hydration rate, water retaining agent reducing surface erosion risk), which makes the mortar strength stability enhanced, and the rheological property and construction performance improved simultaneously. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The nuclear magnetic chart of the anti-ultraviolet agent 1 of the present application. DETAILED DESCRIPTION

[0038] The technical solutions of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0039] A self-leveling mortar for mine tailings, comprising the following raw materials in parts by weight:

[0040] Parts 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, and 35 of cementitious material;

[0041] Mine tailings aggregate in quantities of 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, and 60.

[0042] Limestone powder in parts 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15;

[0043] Reinforcing fibers: 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;

[0044] Water-reducing agent: 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;

[0045] Defoamer 0.1, 0.2, 0.3, 0.4, 0.5 parts;

[0046] 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;

[0047] 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;

[0048] UV protectant 1 or 2 parts;

[0049] Water portions 15, 16, 17, 18, 19, and 20.

[0050] Preparation Example 1

[0051] Synthesis of UV stabilizer 1:

[0052] The synthesis of UV stabilizer 1 is achieved through a two-step chemical reaction, specifically:

[0053] first step:

[0054] ;

[0055] Into a flask containing 250 ml of DMSO, 20 g of raw material 1 and 10.49 g of raw material 2 were added, and the resulting reaction mixture was stirred for 5 min. After replacing the air with nitrogen, 10.55 g of potassium tert-butoxide was added under continuous nitrogen protection, and then the temperature of the system was raised to 65°C, and the reaction was carried out for 8 h. The reaction was monitored by HPLC, and after the reaction was completed, the mixture was poured into 0°C water, stirred for 15 min, extracted with ethyl acetate, and the organic phase was retained and rotary evaporated. The powder after rotary evaporation was purified by column chromatography (silica gel, eluent: petroleum ether / ethyl acetate), and then rotary evaporated again to obtain 21.56 g of intermediate 1. Mass spectrum MS+1: 531.

[0056] Second step:

[0057] ;

[0058] 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 to reflux for 12 h; after the reaction was completed, the temperature was slightly lowered, and diatomite was used for filtration, and after the filtrate was cooled to room temperature, it was washed with water three times, and the organic phase was retained, and then the aqueous phase was extracted with ethyl acetate, and the combined organic phase was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated. The powder after rotary evaporation was purified by column chromatography (silica gel, eluent: petroleum ether / ethyl acetate), and then rotary evaporated again to obtain 25.20 g of anti-UV agent 1. Mass spectrum MS+1: 769. NMR is shown in Table 1. Figure 1 .

[0059] Preparation Examples 2-6

[0060] Anti-UV agents 2-6 were prepared in turn in Preparation Examples 2-6, and the preparation method of Preparation Example 1 was referred to, and raw material 2 therein was replaced, and the rest was the same as Preparation Example 1. The specific structure of raw material 2, the structures of anti-UV agents 2-6, and the mass spectrum MS+1 data are shown in Table 1.

[0061] Table 1.

[0062] Example 1

[0063] Preparation of a mine tailings self-leveling mortar:

[0064] 1. Raw material ratio:

[0065] Cementitious material: 30 parts, selected from: P.O 42.5 Portland cement, purchased from Tangshan Tianlu Cement Co., Ltd.

[0066] Mine tailings aggregate: 50 parts, selected from: Iron mine tailings, fineness modulus of 2.0, purchased from Fujian Makeng Mining Co., Ltd., dried at 105°C for pretreatment to a water content of ≤0.5%;

[0067] Limestone powder: 10 parts, selected from: particle size ≤30 μm (D90 value), purchased from Wuhan Deyi Environmental Protection New Material Co., Ltd.;

[0068] Reinforcing fiber: 1.0 part, selected from: polypropylene fiber, average length 6 mm, purchased from Shandong Lufan Building Material Technology Co., Ltd.;

[0069] Water reducing agent: 0.8 parts, selected from: naphthalene-based water reducing agent, SBTJM ® -B naphthalene-based high-efficiency water reducing agent, purchased from Jiangsu Suobot New Material Co., Ltd.;

[0070] Defoaming agent: 0.3 parts, selected from: polyether-modified silicone defoaming agent DT-650, purchased from Foshan Nanhai Datian Chemical Co., Ltd.;

[0071] Water retaining agent: 0.15 parts, selected from: hydroxypropyl methylcellulose ether, purchased from Zhejiang Haishen New Material Co., Ltd.;

[0072] Retarder: 0.1 part, selected from: sodium gluconate, purity ≥99%, purchased from Shandong Beida Gaokexue Huatai Pharmaceutical Co., Ltd.;

[0073] Anti-ultraviolet agent: 1.5 parts, selected from: anti-ultraviolet agent 1 prepared in Preparation Example 1;

[0074] Water: tap water, 18 parts.

[0075] 2. Preparation method:

[0076] S1. The dried iron mine tailings, Portland cement, polypropylene fiber, hydroxypropyl methylcellulose ether and sodium gluconate were added to a planetary mixer and mixed at a speed of 400 rpm for 4 minutes to obtain a premixed dry material;

[0077] S2. The limestone powder, naphthalene-based water reducing agent and anti-ultraviolet agent 1 were added to the premixed dry material, and the mixing was continued at a speed of 400 rpm for 10 minutes, and the temperature was controlled ≤30°C during the mixing process to obtain a mixed dry material;

[0078] S3. The mixed dry materials are transferred to the mixer, and water is added in portions, 70% of the total water (i.e. 12.6 parts) is added first, and the speed is adjusted to 500 rpm for 3 minutes; then the remaining 30% water (5.4 parts) is added under continuous stirring, and the defoaming agent DT-650 is added, and mixed at a speed of 500 rpm for 10 minutes, to obtain a uniform, bubble-free mine tailings self-leveling mortar.

[0079] Examples 2-6

[0080] A mine tailings self-leveling mortar is prepared according to the preparation method of Example 1, and the anti-ultraviolet agent therein is replaced by anti-ultraviolet agent 2-anti-ultraviolet agent 6 in turn, and the rest remains the same as Example 1.

[0081] In order to better highlight the technical effects of the present application, the following comparative examples are provided:

[0082] Comparative Example 1

[0083] A mine tailings self-leveling mortar is prepared according to the preparation method of Example 1, and the anti-ultraviolet agent therein is replaced by ultraviolet absorber UV-1577 (Ciba Specialty Chemicals) ) in turn, and the rest remains the same as Example 1.

[0084] Comparative Example 2

[0085] A mine tailings self-leveling mortar is prepared according to the preparation method of Example 1, and the anti-ultraviolet agent therein is replaced by comparative compound 1 in turn, and the rest remains the same as Example 1.

[0086] Comparative Compound 1: .

[0087] Comparative Example 3

[0088] A mine tailings self-leveling mortar is prepared according to the preparation method of Example 1, and the anti-ultraviolet agent therein is replaced by comparative compound 2 in turn, and the rest remains the same as Example 1.

[0089] Comparative Compound 2: .

[0090] Comparative Example 4

[0091] A mine tailings self-leveling mortar is prepared according to the preparation method of Example 1, and the anti-ultraviolet agent therein is replaced by ultraviolet absorber-928 (Rohm and Haas) ) in turn, and the rest remains the same as Example 1.

[0092] Comparative Example 5

[0093] A mine tailings self-leveling mortar was prepared according to the preparation method of Example 1, without adding the water reducing agent therein, and the rest was kept the same as Example 1.

[0094] Comparative Example 6

[0095] A mine tailings self-leveling mortar was prepared according to the preparation method of Example 1, without adding the water retaining agent therein, and the rest was kept the same as Example 1.

[0096] Comparative Example 7

[0097] A mine tailings self-leveling mortar was prepared according to the preparation method of Example 1, without adding the reinforcing fiber therein, and the rest was kept the same as Example 1.

[0098] Performance test:

[0099] The mine tailings self-leveling mortar prepared in the above examples and comparative examples was tested for its flexural strength (MPa) and compressive strength (MPa) after natural standing for 28 days according to the test method of JC / T 985-2017 “Cement-based self-leveling mortar for ground use”, and the data are shown in Table 2.

[0100] The mine tailings self-leveling mortar prepared in the above examples and comparative examples was tested according to ASTM G154 “Standard Practice for Operating Fluorescent Ultraviolet Lamp Apparatus for UV Weathering”, a mine tailings self-leveling mortar was cast into a standard test piece (such as 40 mm x 40 mm x 160 mm), cured for 7 days under standard conditions (20 ± 2 ℃, RH ≥ 95%), and naturally stood for 28 days, and then the test piece was placed in a UV aging test box, the UV wavelength was UVA-340, the irradiation intensity was 0.76 W / m 2 , the aging period was 1000 h, UV irradiation for 8 hours + condensation for 4 hours every 8 hours to simulate the real environment, the cracking, peeling or discoloration of the test piece after aging was observed, the flexural strength and compressive strength after aging (based on the method of JC / T985-2017) were measured, and the strength loss rate (%) was calculated.

[0101] Table 2.

[0102]

[0103] The example group showed a higher stability trend in 28-day flexural and compressive strength, and the strength loss rate after aging was significantly lower than the comparative group, reflecting its excellent ultraviolet aging resistance and durability. In contrast, the comparative group (including the use of alternative ultraviolet absorbers or the absence of key ingredients such as water-reducing agents, water-retaining agents, or reinforcing fibers) showed a general trend of lower strength, with a significantly increased loss rate, especially when using standard ultraviolet absorbers or when ingredients were missing, highlighting the optimization of the ultraviolet-resistant agent of the present application in synergy with other components for the long-term performance of the mortar. This indicates that the formulation of the present application effectively suppresses the degradation problem induced by ultraviolet light through material selection and additive integration.

[0104] While embodiments of the present application have been shown and described, it is to be understood that the embodiments can be varied, modified, replaced and altered in many ways, without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A mine tailings self-leveling mortar, characterized in that, Consists of raw materials comprising: cementing material 20-35 parts, mine tailings aggregate 40-60 parts, limestone powder 5-15 parts, reinforcing fiber 0.5-2 parts, water reducing agent 0.3-1.5 parts, defoaming agent 0.1-0.5 parts, water retaining agent 0.05-0.3 parts, retarder 0.05-0.2 parts, ultraviolet resistant agent 1-2 parts, water 15-20 parts; The ultraviolet resistant agent is a compound represented by formula 1: Formula 1; R1 in the formula 1 is a substituent group, and R1 is selected from the group consisting of alkyl with carbon atom number of 1-5, alkoxy with carbon atom number of 1-5, and aryl with carbon atom number of 6-10.

2. A mine tailings self-leveling mortar as claimed in claim 1, characterized in that, The cementing material is at least one of Portland cement and sulphoaluminate cement. The mine tailings aggregate is one of iron mine tailings, copper mine tailings or gold mine tailings, and the fineness modulus is 1.8-2.

5.

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

4. A mine tailings self-leveling mortar as claimed in claim 1, characterized in that, The reinforcing fiber is one of polypropylene fiber and polyvinyl alcohol fiber, and the length is 3-12mm.

5. A mine tailings self-leveling mortar as claimed in claim 1, characterized in that, The water reducing agent is naphthalene series water reducing agent. The defoaming agent is polyether modified silicone defoaming agent DT-650. The water retaining agent is hydroxypropyl methyl cellulose ether.

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

7. A mine tailings self-leveling mortar as claimed in claim 1, characterized in that, The ultraviolet resistant agent is a compound represented by any one of the following structures: ； 。 8. A method of preparing a mine tailings self-leveling mortar according to any one of claims 1 to 7, characterized in that, Comprising the following steps: S1. The cementing material, mine tailings aggregate, reinforcing fiber, water retaining agent and retarder are added to a mixing machine, and mixed at 300-500rpm for 3-5 minutes to obtain a premixed dry material; S2. The limestone powder, water reducing agent and ultraviolet resistant agent are added to the premixed dry material, and continue to mix for 8-12 minutes to obtain a mixed dry material; S3. The water is added to the mixed dry material in portions, the mixer is adjusted to 800-1000rpm, mixed for 5-8 minutes, the defoaming agent is added, and mixed at 400-600rpm for 5-15 minutes to obtain a mine tailings self-leveling mortar.

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

10. A method of preparing a mine tailings self-leveling mortar according to claim 8, characterized in that, The water in S3 is added in two portions, 70% of the total amount is mixed for 3 minutes, and the remaining 30% is added during mixing.

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