A mine filling cementitious material suitable for high-cold and high-altitude areas and a preparation method thereof

Abstract

The present invention belongs to cementitious materials, and specifically relates to a mine filling cementitious material suitable for high-cold and high-altitude areas and a preparation method thereof. The mine filling cementitious material suitable for high-cold and high-altitude areas includes the following raw materials in parts by weight: 30 to 60 parts of granulated blast furnace slag powder, 5 to 20 parts of ultrafine steel slag powder, 1 to 30 parts of gypsum, 10 to 30 parts of ordinary Portland cement, and 2 to 10 parts of low-temperature resistant composite activator. The mine filling cementitious material innovated by the present invention is particularly suitable for high-cold and high-altitude environments. Even under extreme high-cold and high-altitude conditions, the formula of the invention can still ensure that the mechanical strength of the 28-day-old filling body is significantly improved, and the slurry has good expansion and fluidity can achieve self-flowing transportation.

Description

Technical Field

[0001] The invention belongs to cementitious materials, and in particular relates to a mine filling cementitious material suitable for high-cold and high-altitude areas and a preparation method thereof. Background Art

[0002] With the increasing global awareness of environmental protection and the profound understanding of the non-renewable nature of resources, the circular economy model is leading the mining industry to develop in a more sustainable direction. In this context, backfill mining technology, as an efficient and environmentally friendly mining method, is increasingly highlighting its dominant position in the future development of the mining industry. This technology not only effectively addresses the thorny issue of tailings disposal, but also significantly reduces the discharge and storage area of ​​tailings through large-scale backfilling of goafs, thereby promoting the maximum utilization of resources. Specifically, this technology cleverly mixes concentrated tailings with cementitious materials in a specific proportion to make a high-concentration backfill mortar, which is accurately injected into the goaf area to form a stable backfill body with a certain bearing capacity. This process not only realizes the effective utilization of tailings and reduces environmental pollution, but also significantly enhances the structural stability of the mine, providing a strong guarantee for the safe production of the mine.

[0003] Although the backfill mining method has shown great potential in terms of efficient resource utilization and environmental protection, its high cost has always been one of the key factors restricting its widespread application, especially in the mining of high-value rare deposits. However, in recent years, with the continuous innovation and breakthroughs in backfill technology and the continuous improvement of environmental protection requirements, the application ratio of backfill mining in underground mines, especially underground copper polymetallic mines, is steadily increasing, indicating that this will be an irreversible trend in the development of mineral resources at home and abroad.

[0004] At the same time, with the continuous expansion of mining activities, more and more mining development projects are concentrated in areas with extreme geographical conditions, especially in high-altitude and cold regions. These severe geographical conditions pose great challenges to mines that adopt the backfilling method and put forward higher requirements for backfilling cementitious materials. Traditionally, cement, as the main cementitious material, has played a key role in mine backfilling. However, under high-altitude and cold conditions, the use of cement to backfill mine goafs faces many challenges, and its performance is often unsatisfactory.

[0005] At present, the main filling material for mines is cement, but the defects of cement in high-altitude and cold areas are as follows:

[0006] (1) Low strength and poor low-temperature performance. In cold environments, cement strength cannot grow steadily and rapidly, and the 28-day strength cannot meet the requirements of mine recovery. In addition, the early strength growth of cement paste is slow, which makes it difficult to meet the needs of rapid recovery, affecting the progress of mine mining. At the same time, concrete is prone to freeze-thaw cycle damage in low-temperature environments, reducing the long-term stability of the filling body.

[0007] (2) Unable to consolidate large amounts of tailings, resulting in low tailings utilization. Cement cannot consolidate large amounts of tailings under extremely cold conditions, and the accumulation of tailings ponds puts considerable pressure on the environment and the economy, greatly affecting mining efficiency.

[0008] (3) The expansion and fluidity of cement filling slurry are poor, which cannot meet the requirements of gravity transportation and increases energy and power consumption.

[0009] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the invention

[0010] In order to solve the problems existing in the prior art, the present invention provides a mine filling cementitious material suitable for high-cold and high-altitude areas, comprising the following raw materials in parts by weight: 30 to 60 parts of granulated blast furnace slag powder, 5 to 20 parts of ultrafine steel slag powder, 1 to 30 parts of gypsum, 10 to 30 parts of ordinary Portland cement, and 2 to 10 parts of low-temperature resistant composite activator.

[0011] Preferably, the mine filling cementitious material suitable for high-cold and high-altitude areas includes the following raw materials in parts by weight: 50 parts of granulated blast furnace slag powder, 10 parts of ultrafine steel slag powder, 20 parts of gypsum, 20 parts of ordinary Portland cement, and 5 parts of low-temperature resistant composite activator.

[0012] Preferably, the particle size of the granulated blast furnace slag powder is: D97≤50 μm.

[0013] Preferably, the particle size of the ultrafine steel slag powder is: D97≤50μm.

[0014] Preferably, the gypsum is natural gypsum, industrial by-product gypsum, or a combination of both;

[0015] And / or, the particle size of the gypsum is: D97≤100 μm.

[0016] Preferably, the grade of the ordinary Portland cement is 42.5 or 52.5.

[0017] Preferably, the low temperature resistant composite activator is one or a combination of two or more of an early strength agent, an alkali activator, and a surfactant;

[0018] And / or, the early strength agent is one or a combination of two or more of a chloride-based early strength agent, a sulfate-based early strength agent, and an organic-based early strength agent;

[0019] And / or, the alkaline activator is one or a combination of two or more of caustic soda, silicate, aluminate, phosphate, sulfate and carbonate containing alkaline elements;

[0020] And / or, the surfactant is an ionic surfactant, a non-ionic surfactant, or a combination of both.

[0021] Based on the same technical concept, another solution of the present invention is to provide a method for preparing the mine filling cementitious material suitable for high-cold and high-altitude areas, the preparation method comprising the following steps:

[0022] (1) Grinding gypsum and ordinary Portland cement to obtain auxiliary material powder;

[0023] (2) uniformly mixing one or more of an early strength agent, an alkali activator, and a surfactant in a certain proportion to obtain a low-temperature resistant composite activator powder;

[0024] (3) The auxiliary material powder, granulated blast furnace slag powder, ultrafine steel slag powder, and low-temperature resistant composite activator powder are uniformly mixed to obtain a mine filling cementitious material suitable for high-cold and high-altitude areas.

[0025] Preferably, the specific surface area of ​​the mine filling cementitious material suitable for high-cold and high-altitude areas is ≥650m 2 / kg.

[0026] It should be noted that dry tailings and water are added during use. Preferably, tailings slurry is added during use.

[0027] The beneficial effects of the present invention are:

[0028] The innovative mine filling cementitious material of the present invention is particularly suitable for high-cold and high-altitude environments. Even under extreme high-cold and high-altitude conditions, the formula of the invention can still ensure that the mechanical strength of the 28-day-old filling body is significantly improved, and the slurry expansion is good, and the fluidity can reach self-flowing transportation. The mine filling cementitious material achieves complementary advantages of each component through the reasonable proportion of granulated blast furnace slag powder and ultrafine steel slag powder, cement, gypsum and low-temperature resistant composite activator. The secondary hydration reaction and filling effect of slag powder, combined with the strong hydration ability of cement and the regulation and strengthening effect of a small amount of gypsum, jointly promote the generation of hydration products inside the material and the optimization of the microstructure. The various expansive hydration products such as calcium sulfonate formed significantly improve the density of the material, reduce internal pores and defects, and thus enhance the overall strength of the material. The low-temperature resistant composite activator can improve the early strength of the filling body, still maintain its activity at low temperatures, improve the low-temperature performance of the cementitious material, and also improve the uniformity and density of the filling body, thereby improving the strength performance and pumping capacity of the filling body.

[0029] At the same time, the mine filling cementitious material of the present invention can consolidate a large amount of tailings, and the strength achieved when the lime-sand ratio is 1:9 is higher than the strength of cement when the ratio is 1:4, that is, under the same strength requirement, compared with cement, the mine filling cementitious material of the present invention can consolidate the amount of tailings that is 2 times or more of the amount of cement consolidation. This characteristic improves the problems of strength attenuation, low fluidity, and less consolidated tailings of mine filling cementitious materials in high cold and high altitudes. DETAILED DESCRIPTION

[0030] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment provides a method for preparing a mine filling cementitious material suitable for use in cold and high altitude areas, the method comprising the following steps:

[0033] S1. A copper polymetallic mine in a high-altitude and cold area, at an altitude of 4,500 meters, the mine filling cementitious materials are prepared according to the following weight ratio: 50kg of S95 granulated blast furnace slag powder, 10kg of ultrafine steel slag powder, 20kg of natural anhydrous gypsum, 20kg of ordinary silicate 52.5 cement, and 5kg of low-temperature resistant composite activator; the low-temperature resistant composite activator is composed of triethanolamine and nano-silicon dioxide, with 0.5kg of triethanolamine and 4.5kg of nano-silicon dioxide.

[0034] S2, grinding natural anhydrous gypsum and ordinary Portland cement together to form auxiliary material powder;

[0035] S3, mix the auxiliary material powder, S95 granulated blast furnace slag powder, ultrafine steel slag powder and low temperature resistant composite activator evenly according to the components to ensure that the specific surface area of ​​the powder is ≥650m 2 / kg, the resulting mine filling cementitious material is suitable for use in cold and high altitude areas.

[0036] Then, further testing:

[0037] S4. Mixing and stirring: During the test, a JJ-20H cement mortar mixer was used for mixing: first put down the base of the mixing barrel, remove the mixing barrel, and mix the tailings and mine filling cementitious material into the mixing barrel, then put the mixing barrel back on the base, and after ensuring that the bottom tip of the agitator and the mixing barrel maintain a minimum distance (5-10mm), tighten the base fixing bolts to fix the mixing barrel on the agitator base, then start the machine and stir for 1 minute. After the stirring is completed, add water to the mixing barrel and continue stirring (>4 minutes) until the tailings and the new cementitious material are evenly mixed.

[0038] S5. Mold pouring: The three-piece mold must be placed flat before mold pouring. To ensure that the slurry fills a test mold after settling, a duplicate mold must be placed on the test mold. In addition, to prevent the test mold from leaking slurry, the mold is sealed with butter around the outside and engine oil is applied to the inside of the mold to facilitate demolding.

[0039] S6. Tamping: After pouring, tamp (not stratified). Use a tamping rod to tamp evenly from outside to inside in a spiral direction for 25 times.

[0040] S7. Scrape the mold: When excess water is removed from the top of the test mold and pockmarks appear on the surface of the slurry, remove the re-mold, scrape off the excess slurry on the top of the test mold with a spatula, and smooth the test piece along the top surface.

[0041] S8. Demolding and curing: demould after 48h±2h after casting, and then place in YH-60B constant temperature and humidity standard curing box for curing. The curing box is set at 20±2℃, relative humidity greater than 90%, and the spacing between test blocks is greater than 10mm.

[0042] S9. Compression strength test: The test adopts WDW-50 electronic universal testing machine for pressure test. The loading rate of the pressure testing machine is 5mm / min, the range of the pressure sensor is 50000N, and the press is calibrated before the test.

[0043] The experimental data of uniaxial compressive strength of the filling body of Example 1 are shown in Table 1.

[0044] Table 1 Example 1 Filling body strength

[0045]

[0046] Note: Filling concentration refers to the percentage of the sum of the mass of dry tailings and cementitious materials in the filling slurry to the total mass of the filling slurry. The same applies below.

[0047] S10. The expansion test is carried out in accordance with the Technical Standard for Metal and Non-metal Mining Backfill Engineering GB / T51450-2022, specifically:

[0048] S11. Test equipment: truncated cone circular mold (upper diameter 36mm, lower diameter 60mm, height 60mm, smooth inner wall without joints), steel ruler (size 300mm), glass plate (size 400mm×400mm×5mm).

[0049] S12. Test steps: Place the glass plate in a horizontal position, wipe the glass plate and the truncated cone mold with a wet cloth, and then place the moistened truncated cone mold in the center of the glass plate; quickly pour the prepared filling slurry into the truncated cone mold and flatten the upper opening with a spatula; after removing the slurry on the glass plate at the edge of the cylinder, lift the truncated cone mold vertically and steadily, and start the stopwatch at the same time. When the slurry stops diffusing or the diffusion duration has reached 30s, use a steel ruler to measure the maximum diameters of the two directions perpendicular to each other of the flowing part of the slurry, and take the average value as the expansion degree of the filling slurry.

[0050] S13. The experimental data of slurry expansion degree of Example 1 are shown in Table 2.

[0051] Table 2 Degree of expansion of Example 1

[0052]

[0053]

[0054] Example 2

[0055] This embodiment provides a method for preparing a mine filling cementitious material suitable for use in cold and high altitude areas, the method comprising the following steps:

[0056] S1. A copper polymetallic mine in a high-altitude and cold area of ​​a certain plateau, with an altitude of 4,500 meters, the mine filling cementitious materials are prepared according to the following weight ratio: 60kg of S95 granulated blast furnace slag powder, 5kg of ultrafine steel slag powder, 10kg of natural anhydrous gypsum, 25kg of ordinary silicate 52.5 cement, and 5.5kg of low-temperature resistant composite activator; the low-temperature resistant composite activator is composed of triethanolamine, nano-silicon dioxide, and sodium carbonate, with 0.5kg of triethanolamine, 3.5kg of nano-silicon dioxide, and 1.5kg of sodium carbonate.

[0057] S2. Prepare test blocks according to the method in Example 1 and test their performance.

[0058] S3. The experimental data of the filling body of Example 2 are shown in Table 3, and the experimental data of the expansion degree are shown in Table 4.

[0059] Table 3 Example 2 Filling Body Strength

[0060]

[0061]

[0062] Table 4 Expansion of Example 2

[0063]

[0064]

[0065] Comparative Example 1

[0066] S1. Compared with Examples 1 and 2, the mine filling cementitious material of the present invention is replaced with P.O42.5 cement produced by the same cement plant, and the dosage of other components, tailings slurry concentration, and ash-sand ratio are the same as those described in Examples 1 and 2. The copper polymetallic mine in the high-altitude and cold regions is the same as in the examples, with an altitude of 4500 meters.

[0067] S2. Prepare test blocks according to the method in Example 1 and test their performance.

[0068] S3. The experimental data of the filling body of comparative example 1 are shown in Table 5, and the experimental data of the expansion degree are shown in Table 6.

[0069] Table 5 Comparative Example 1 Filling Body Strength

[0070]

[0071]

[0072] Table 6 Expansion of Comparative Example 1

[0073]

[0074]

[0075] Embodiment 1 and embodiment 2 of the present invention are embodiments with relatively excellent comprehensive performance. Comparative Example 1 replaces the mine filling cementitious material of the present invention with ordinary silicate 42.5 cement. Under the same experimental conditions, the strength is significantly reduced. The cement control group has better strength performance only when the tailings slurry concentration is high and the ash-sand ratio is low, but it is still not as good as embodiment 1 and embodiment 2. Cement cannot consolidate tailings when the tailings slurry concentration is low, nor can it consolidate a large amount of tailings. The ash-sand ratio in the above embodiments represents the amount of consolidated tailings. Under the same tailings slurry concentration, under the condition of meeting the strength requirements, the amount of consolidated tailings by the mine filling cementitious material of the present invention is twice that of cement. Compared with embodiment 1 and embodiment 2, embodiment 2 is more suitable for high concentration and low ash-sand ratio, and is more excellent in the performance of early strength improvement. The filling slurry expansion of embodiment 1 and embodiment 2 under different ash-sand ratios is 34.8cm-18cm at a filling concentration of 60-72%, and the filling slurry expansion of the comparative example is 32.75cm-16.25cm. Under the same filling concentration, from the specific data analysis, the filling slurry expansion of Example 1 and Example 2 is increased by an average of 7.46% compared with that of Comparative Example 1. Therefore, under the condition of meeting the fluidity requirements, the fluidity of the mine filling cementitious material of the present invention is better than that of cement.

[0076] The mine filling cementitious material of the present invention optimizes the proportion of various micropowders and low-temperature resistant composite activators and utilizes the complementary advantages of each component to promote the generation and structural optimization of hydration products. In particular, the formed expansive hydration products improve the material density, reduce defects, ensure solidification in a low-temperature environment, and improve the fluidity and pumpability of the filling body, thereby significantly enhancing the overall strength.

[0077] The above-mentioned Embodiment 1 and Embodiment 2 are only preferred embodiments of the present invention and are not used to limit the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the invention.

Claims

1. A mine filling cementitious material suitable for use in cold and high altitude areas, characterized in that: The invention comprises the following raw materials in parts by weight: 30-60 parts of granulated blast furnace slag powder, 5-20 parts of ultrafine steel slag powder, 1-30 parts of gypsum, 10-30 parts of ordinary Portland cement and 2-10 parts of low temperature resistant composite activator.

2. The mine filling cementitious material suitable for high-cold and high-altitude areas according to claim 1 is characterized in that: The invention comprises the following raw materials in parts by weight: 50 parts of granulated blast furnace slag powder, 10 parts of ultrafine steel slag powder, 20 parts of gypsum, 20 parts of ordinary Portland cement and 5 parts of low temperature resistant composite activator.

3. The mine filling cementitious material suitable for high-cold and high-altitude areas according to claim 1 is characterized in that: The particle size of the granulated blast furnace slag powder is: D97≤50μm.

4. The mine filling cementitious material suitable for high-cold and high-altitude areas according to claim 1 is characterized in that: The particle size of the ultrafine steel slag powder is: D97≤50μm.

5. The mine filling cementitious material suitable for high-cold and high-altitude areas according to claim 1 is characterized in that: The gypsum is one or a combination of natural gypsum and industrial by-product gypsum; And / or, the particle size of the gypsum is: D97≤100 μm.

6. The mine filling cementitious material suitable for high-cold and high-altitude areas according to claim 1 is characterized in that: The model of the ordinary Portland cement is 42.5 grade or 52.5 grade.

7. The mine filling cementitious material suitable for high-cold and high-altitude areas according to claim 1 is characterized in that: The low temperature resistant composite activator is one or a combination of two or more of an early strength agent, an alkali activator and a surfactant; And / or, the early strength agent is one or a combination of two or more of a chloride-based early strength agent, a sulfate-based early strength agent, and an organic-based early strength agent; And / or, the alkaline activator is one or a combination of two or more of caustic soda, silicate, aluminate, phosphate, sulfate and carbonate containing alkaline elements; And / or, the surfactant is an ionic surfactant, a non-ionic surfactant, or a combination of both.

8. The method for preparing the mine filling cementitious material suitable for high-cold and high-altitude areas according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) Grinding gypsum and ordinary Portland cement to obtain auxiliary material powder; (2) The auxiliary material powder, granulated blast furnace slag powder, ultrafine steel slag powder and low temperature resistant composite activator are uniformly mixed to obtain a mine filling cementitious material suitable for high-altitude and cold regions.

9. The preparation method according to claim 8, characterized in that: The specific surface area of ​​the mine filling cementitious material suitable for high-cold and high-altitude areas is ≥650m 2 / kg.

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