Low-temperature foamed inorganic filler material, method for producing same, and use thereof

Abstract

The present application relates to a kind of low-temperature foamed inorganic filling material and its preparation method and application, belong to grouting filling reinforcement field.For the low foaming efficiency of existing inorganic system at low temperature, cement and sodium silicate are used as the main component of filling material, carbonate is used as the main foaming agent, dolomite is used as the auxiliary foaming agent, carbon dioxide is released in two stages by organic phosphonic acid and citric acid, and a composite foam stabilizing system is constructed by combining nano-silica and sodium carboxymethyl cellulose.The filling material can quickly foam at low temperature, with high foaming rate, good stability, and good compressive strength.The test results show that the foaming ratio is ≥5.4 times at 5℃, the half-life is ≥35min, and the 7d compressive strength is ≥8.4MPa.The technical problems of low foaming efficiency and poor foam stability of traditional inorganic grouting material at low temperature are solved, and the filling material is suitable for low-temperature grouting engineering in coal mine.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of grouting filling and reinforcement, and particularly relates to a low-temperature foaming inorganic filling material as well as a preparation method and application thereof. The filling material can be rapidly foamed at low temperature, has high foaming rate, good stability and excellent compressive strength. BACKGROUND

[0002] The grouting filling technology uses special equipment to press low-viscosity chemical slurry into fissures of surrounding rock or loose rock mass. The slurry is gelled and solidified in a very short time to form a three-dimensional network consolidation body, which re-cements the originally broken and loose structure into a continuous and complete stress whole, thereby repairing structural defects and improving bearing capacity and anti-seepage capacity. The process is simple and the effect is remarkable. In recent years, it has been widely used in the field of mining and other fields.

[0003] The double-liquid chemical foaming slurry is mixed on site by A and B two independent components, and after being injected into the stratum, it rapidly reacts, expands and solidifies to form a reinforcement-plugging integrated structure. According to the working condition requirements, a catalyst can be appropriately added to achieve rapid plugging in high water velocity stratum, and the effect of surrounding rock reinforcement and anti-seepage is particularly remarkable. The double-liquid foaming system with inorganic filler as the core has high foaming and instantaneous solidification capacity, can efficiently fill and plug water inrush in broken stratum or coal mine fissures; its low-temperature reaction characteristics ensure the safety of gas environment, it is solvent-free, flame-retardant and low-cost, and the construction is simple, and the engineering efficiency is greatly improved. The commonly used inorganic grouting materials mainly include cement-based and water glass-based two types: the cement-based material has low cost and high strength, but has poor foaming capacity, large heat release and poor flowability; and the existing inorganic system has low foaming efficiency, unstable foam and difficult-to-control setting time at low temperature, which affects the mechanical properties and restricts the construction quality and efficiency.

[0004] The foaming agent for grouting material mainly includes hydrogen peroxide foaming agent and carbonate foaming agent. In a low-temperature environment, the decomposition rate of hydrogen peroxide significantly slows down or even may be difficult to effectively decompose, resulting in a significant discount in foaming effect, which cannot produce enough gas to form an ideal foam structure, affecting the foaming performance and final porosity and other performance indicators of the material. The hydrogen peroxide foaming agent is unstable in nature and is prone to decomposition failure, and needs to be stored under specific conditions such as low temperature, light avoidance and sealing, otherwise it will lose the foaming effect due to premature decomposition, increasing the difficulty and cost of use and storage.

[0005] Carbonate foaming agent is widely used in grouting foaming agent because of low cost, good safety and good low temperature applicability. However, the amount of carbon dioxide gas produced by complete decomposition of sodium bicarbonate per unit mass of carbonate is low, and a large amount of addition is required to achieve good foaming effect, which has an adverse effect on other properties of the material (such as strength). At the same time, the foaming rate is too fast, CO2 is released in 10-30 seconds, the bubbles merge into millimeter-sized large bubbles, and the bubbles cannot provide good foaming performance for the grouting material continuously and stably. In addition, the foam is poor in stability, the foam layer is fragile, and is easily broken by external factors such as shear force generated by material flow in the grouting process, self-gravity and underground humidity, so that the foam is difficult to maintain uniformity and stability for a long time, which seriously affects the performance of the grouting material.

[0006] Therefore, it has important practical significance to develop an inorganic filling material with good low-temperature foaming performance, high stability and low cost suitable for coal mine grouting. SUMMARY

[0007] The application provides an inorganic filling material suitable for low-temperature environment and a preparation method and application thereof. Carbonate is used as the main foaming agent, and dolomite is used as the auxiliary foaming agent. Carbon dioxide is released in stages through the synergistic effect of organic phosphonic acid and citric acid. A composite foam stabilizing system is constructed by combining nano-silicon dioxide and sodium carboxymethyl cellulose, which significantly reduces the amount of carbonate, simultaneously improves the foaming ratio and the compressive strength, and effectively solves the problems of high dosage, poor foam stability and weak compressive strength of traditional carbonate foaming agent in low-temperature grouting.

[0008] The application provides an inorganic filling material for low-temperature foaming, which comprises A component and B component.

[0009] The A component comprises the following raw materials in parts by weight: cement 10-40 parts, sodium silicate 10-30 parts, dolomite 10-30 parts, foam stabilizer 1-5 parts, foaming agent 2-10 parts, surfactant 2-6 parts, and water 30-60 parts.

[0010] The B component comprises the following raw materials in parts by weight: organic phosphonic acid 5-15 parts, citric acid 3-10 parts, additive 5-15 parts, and water 30-70 parts.

[0011] The mass ratio of the A component to the B component is 1:1.

[0012] Preferably, the cement of the A component is at least one of Portland cement, phosphate cement and aluminosilicate cement.

[0013] Preferably, the foaming agent of the A component is at least one of sodium bicarbonate, potassium bicarbonate, sodium carbonate or potassium carbonate.

[0014] Preferably, the particle size of the dolomite is 1-50 microns, preferably 5-20 μm, and the modulus of the sodium silicate is 2.4-2.8.

[0015] Preferably, the foam stabilizer of the A component is nano-silica and sodium carboxymethyl cellulose, and the mass ratio of the nano-silica and sodium carboxymethyl cellulose is 10:1-3.

[0016] Preferably, the surfactant of the A component is a mixture of one or more of Tween 80, Span 60, sodium dodecyl sulfate or sodium dodecyl benzene sulfonate.

[0017] Preferably, the organic phosphonic acid of the B component is at least one of amino trimethylene phosphonic acid, hydroxy ethylene diphosphonic acid, methyl amine dimethylene phosphonic acid, glycine dimethylene phosphonic acid, ethylene diamine tetramethylene phosphonic acid, amino ethylene diphosphonic acid.

[0018] Preferably, the B component auxiliary agent is at least one of a water reducing agent, an early strength agent, and a retarder. Preferably, the water reducing agent is at least one of a polycarboxylic acid type water reducing agent and a melamine resin type water reducing agent; the early strength agent is at least one of sodium gluconate and sodium hexametaphosphate; and the retarder is at least one of triethanolamine and sodium formate.

[0019] Preferably, the application further provides a preparation method of the low-temperature foamed inorganic filling material, comprising the following steps:

[0020] (1) Preparation of A component: weigh the cement, sodium silicate, dolomite, foam stabilizer, foaming agent, surfactant and water by weight parts, place them in a mixer, stir uniformly, and obtain a uniform A component slurry;

[0021] (2) Preparation of B component: weigh the organic phosphonic acid, citric acid, auxiliary agent and water by weight parts, place them in a mixer, stir uniformly, and obtain a uniform B component solution;

[0022] (3) Mixed use: when used, the A component and the B component are mixed at a mass ratio of 1:1, and the low-temperature foamed inorganic filling material is obtained.

[0023] Preferably, the stirring speed of step (1) is 300-500 r / min, and the stirring time is 5-10 minutes. The stirring speed of step (2) is 200-400 r / min, and the stirring time is 3-8 minutes. The stirring speed of step (3) is 400-600 r / min, and the stirring time is 1-5 minutes.

[0024] Preferably, the application further provides an application of the low-temperature foamed inorganic filling material in a coal mine, comprising the following steps: adding the A material and the B material to the grouting system at a mass ratio of 1:1 by using a grouting pump, and solidifying and filling by using a grouting machine.

[0025] The present application uses cement and sodium silicate as the main components of the filling material, and the silicate ions can react with calcium hydroxide generated in the cement hydration process to form hydrated calcium silicate gel, which helps to improve the early strength of the filling body structure faster. In addition, the viscous substances such as silica gel generated by the hydrolysis of sodium silicate make the internal structure of the filling body more dense, reduce the porosity, and avoid the situation that the filling body is not strong enough due to local loose structure.

[0026] The present application uses carbonate as the main foaming agent, which reacts with organic phosphonic acid to form carbon dioxide in advance. The generated sodium or potassium organic phosphonate has surface activity, reduces the gas-liquid interfacial tension, forms a dense liquid film, reduces the coalescence and rupture of bubbles, and improves the stability of the foam. The main component of dolomite is calcium magnesium carbonate, which has poorer dispersibility in water than sodium carbonate-based main foaming agents, and its carbon dioxide generation rate is slower, realizing the second-stage foaming. The present application uses the two-stage foaming method to avoid the coalescence and rupture of bubbles, and can provide a sustained and stable foam system in a low-temperature environment. Compared with using one of the acids alone, the combination of organic phosphonic acid and citric acid can more significantly improve the reaction rate of sodium carbonate and dolomite decomposition to generate carbon dioxide, and in a relatively low-temperature environment, it can ensure sufficient carbon dioxide gas to achieve good foaming effect.

[0027] The present application preferably uses dolomite with a particle size of 1-50 microns, and further preferably 5-20 microns. On the one hand, it is beneficial to react with acid to form carbon dioxide and improve the foaming ratio, and on the other hand, it can be used as a filler for unreacted dolomite, dispersed in the interstitial space between cement particles in the cement slurry, to improve the compressive strength of the filling body. The smaller the particle size of dolomite, the faster the foaming reaction rate, the greater the amount of dolomite added, and the higher the foaming ratio of the material. By controlling the amount and particle size of dolomite added, the foaming ratio, foaming rate and strength of the cured foam can be adjusted to meet the grouting needs of different use scenarios.

[0028] The foam stabilizer used in the present application is a composite foam stabilizer with a mass ratio of nano-silicon dioxide to sodium carboxymethyl cellulose of 10:1-3. Nano-silicon dioxide forms a nano-fluid in water, forms a physical barrier on the surface of the liquid film, hinders gas diffusion, and delays foam rupture. At the same time, nano-SiO2 reacts with the hydration product Ca(OH)2 of cement to form secondary C-S-H gel, enhancing the bonding strength of the foam-matrix interface. The carboxyl groups in the carboxymethyl cellulose molecule form hydrogen bonds with water molecules, increasing the viscosity of the slurry. Not only can it improve the stability of the foam, but carboxymethyl cellulose also has the functions of emulsifier and dispersant, which can prevent the agglomeration of nano-silicon dioxide, and the two together improve the stability of the foam of the grouting system.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) The present application adopts a two-component design, and the A component and the B component can be rapidly foamed at low temperature after mixing, with high foaming rate and good foam stability, overcoming the problem that the reaction activity of traditional carbonate foaming agents is reduced at low temperature, and the dosage needs to be greatly increased, and the grouting filling operation can be successfully completed at low temperature, expanding the applicable temperature range of inorganic filling materials.

[0031] (2) By reasonably matching the carbonate and dolomite, and combining the synergistic effect of the organic phosphonic acid and the citric acid, the stage-by-stage release of carbon dioxide is realized, the foaming process is more uniform and stable, the foaming rate is improved, and the compressive strength of the filling body is also obviously improved, better meeting the requirements of the project on the strength and stability of the filling body.

[0032] (3) The raw materials used are inorganic materials or environmentally friendly organic compounds, which are low in cost and pollution-free to the environment, and meet the development trend of green environmental protection.

[0033] (4) The material has good flowability and convenient construction, and can be applied to coal mine grouting engineering under different geological conditions, and has a wide application prospect. DETAILED DESCRIPTION

[0034] In order to more clearly illustrate the purpose, technical scheme and advantages of the present application, the following specific embodiments will be used to explain the technical scheme of the present application. It should be pointed out that these embodiments are only used to illustrate the present application, and do not limit the protection scope of the present application, and the actual protection scope of the present application should be defined by the claims.

[0035] The materials, reagents and the like used in the following examples and comparative examples are commercially available reagents and materials unless otherwise specified. The amount of components in the following examples is 1g per weight part or per part unless otherwise specified.

[0036] I. Preparation of an inorganic filling material foamed at low temperature

[0037] The present application relates to a preparation method of an inorganic filling material foamed at low temperature, which specifically comprises the following steps:

[0038] (1) Preparation of A component: weigh each raw material according to the above weight parts, and place it in a stirrer, and stir at a speed of 300 r / min for 10 minutes to obtain a uniform A component slurry.

[0039] (2) Preparation of B component: each raw material is weighed according to the above weight parts, placed in a blender, and stirred at a speed of 200 r / min for 8 minutes to obtain a uniform B component solution.

[0040] (3) Mixed use: when used, A component and B component are mixed in a mass ratio of 1:1, stirred at a speed of 400 r / min for 5 minutes, and the low-temperature foamed inorganic filling material is obtained.

[0041] Table 1: The mass parts (g) of each component in Examples 1-4 are as follows.

[0042]

[0043] Example 6

[0044] The difference from Example 1 is that the particle size of dolomite is 1 μm, and other conditions are the same as Example 1.

[0045] Example 7

[0046] The difference from Example 1 is that the particle size of dolomite is 10 μm, and other conditions are the same as Example 1.

[0047] Example 8

[0048] The difference from Example 1 is that the particle size of dolomite is 20 μm, and other conditions are the same as Example 1.

[0049] Example 9

[0050] The difference from Example 1 is that the particle size of dolomite is 40 μm, and other conditions are the same as Example 1.

[0051] Table 2: The mass parts (g) of each component in Comparative Examples 1-7 are as follows.

[0052]

[0053] II. Performance evaluation

[0054] The application of low-temperature foamed inorganic filling materials prepared by the examples and comparative examples in coal mine grouting includes the following steps: A material and B material are added to the grouting system in a mass ratio of 1:1 using a grouting pump, and solidification filling is performed using a grouting machine.

[0055] 1. Material mechanical strength test

[0056] According to the standard requirements of AQ / T 1089-2020, the prepared material slurry was first poured into a 10cmx10cmx10cm mold, demolded after 24h, and the test samples were respectively placed in an environment of 25℃ and 5℃, and the relative humidity was 50%, and continued to be cured for 7d, the compressive strength of the material at 7d was tested, and the average value of 5 test samples was selected as the test result of each group of experiments.

[0057] 2, Foaming ratio

[0058] The foaming ratio was tested at 25℃ and 5℃ respectively according to the standard requirements of JC / T 266-2011 "Foamed Concrete".

[0059] 3, Foam half-life

[0060] At 5℃, the prepared A and B groups were mixed at a mass ratio of 1:1, and stirred at a stirring speed of 400r / min for 6min to fully foam and produce uniform foam, and then transferred to a pre-prepared measuring container, and the time required for the foam to dissipate to half was recorded as the foam half-life, which was used to measure the stability of the foam.

[0061] Table 3 Properties of grouting materials of different examples and control examples

[0062]

[0063] According to the test results in Table 3, the low-temperature foamed inorganic filling material of the present application foams rapidly at low temperature, the foaming ratio is ≥4.6 times at 5℃, the foam half-life is ≥30min, the foaming ratio is high and the foam stability is good, which overcomes the problems of traditional carbonate foaming agents, such as low reaction activity at low temperature, large increase in dosage, and poor foam stability. At the same time, the prepared low-temperature foamed inorganic filling material has excellent filling performance in coal mine filling: the compressive strength at 5℃ for 7d is ≥7.5MPa; the compressive strength at 25℃ for 7d is ≥10MPa, which can successfully complete the grouting and filling operation under low temperature conditions, and expand the applicable temperature range of inorganic filling materials.

[0064] Comparing Example 1 and Examples 6-9, it can be seen that the particle size of dolomite has a decisive effect on the foaming ratio and compressive strength of the grouting material. If the particle size is too small, the reaction with acid is rapid, the carbon dioxide generation rate is fast, but it is easy to agglomerate and has poor dispersibility; if the particle size is too large, it is easy to settle and difficult to uniformly suspend. Controlling the particle size of dolomite to 1-50 μm, and preferably 5-20 μm, can balance high reactivity and dispersion stability in a low-temperature environment: on the one hand, the rapid reaction of an appropriate amount of dolomite with acid generates CO2, significantly improving the foaming ratio; on the other hand, the unreacted dolomite fine particles uniformly fill the micro gaps between the cement particles, playing a micro aggregate reinforcing role, and improving the compressive strength of the solidified body. By simultaneously adjusting the amount and particle size of dolomite, the foaming rate, foaming ratio and final compressive strength can be precisely controlled to meet the grouting needs of different working conditions.

[0065] Comparing Example 1 and Comparative Examples 1-2, it can be seen that Comparative Example 1 only uses sodium bicarbonate, and its reactivity will decrease in a low-temperature environment, making it difficult to ensure sufficient and stable carbon dioxide generation, resulting in poor foaming effect and limited foaming ratio. Comparative Example 2 only uses dolomite as a foaming agent, and the carbon dioxide generation rate is relatively slow and the foaming ratio is low, as can be seen from Table 3 that the foaming ratio and foam half-life at 5°C of Comparative Example 2 are significantly lower than those of Example 1. Example 1 uses a combination of carbonate and dolomite, the carbonate first reacts with organic phosphonic acid to form carbon dioxide, and the dolomite generates carbon dioxide at a slower rate, realizing the second-stage foaming. The use of the two-stage foaming method in the present application can avoid the concentration and rupture of bubbles, and also provide a sustained and stable foam system in a low-temperature environment.

[0066] Comparing Example 1 and Comparative Examples 3-4, it can be seen that Comparative Examples 3-4 use a single citric acid or organic phosphonic acid system, and at 25°C they can still obtain a compressive strength and foaming ratio similar to those of Example 1, but at 5°C the compressive strength, foaming ratio and foam half-life all decrease significantly. In contrast, Example 1 uses a combination of organic phosphonic acid and citric acid, which can activate sodium bicarbonate and dolomite at low temperatures, and continuously generate carbon dioxide in two stages, thereby ensuring sufficient foaming. The mechanism is speculated to be as follows: the organic phosphonate generated by the reaction of dolomite and organic phosphonic acid has surface activity, can reduce the gas-liquid interfacial tension, form a dense liquid film, inhibit bubble coalescence and rupture, and improve foam stability; at the same time, the unreacted dolomite particles also play a micro aggregate role, further improving the compressive strength of the filled body.

[0067] From the comparison of Example 1 and Comparative Examples 5-7, it can be seen that Comparative Example 5 does not add a foam stabilizer, and Comparative Examples 6-7 only use any one of nano-silica or sodium carboxymethyl cellulose as a foam stabilizer, so that the foam stability is poor, and the foam half-life is lower than that of Example 1, which further affects the uniformity and stability of the internal structure of the material, resulting in that the performance indicators such as compressive strength and foaming ratio are not as ideal as Example 1 at 25℃ and 5℃. Example 1 uses nano-silica and sodium carboxymethyl cellulose as a synergistic foam stabilizer. Nano-silica forms a nanofluid in water, delaying the rupture of the foam. At the same time, nano-SiO2 reacts with the cement hydration product Ca(OH)2 to generate secondary C-S-H gel, thereby improving the compressive strength. Sodium carboxymethyl cellulose increases the slurry viscosity, and also has emulsifying and dispersing effects, preventing nano-SiO2 from agglomerating. The synergistic effect of the two makes the foam system maintain high stability at room temperature and low temperature, thereby ensuring excellent compressive and foaming properties.

[0068] The above examples are only provided to illustrate the present application and are not intended to limit the possible embodiments of the present application. Based on the disclosure of the present application, those skilled in the art can make various modifications and adjustments. It is not necessary or possible to list all possible embodiments. Any modification, equivalent replacement or improvement made within the basic principles and scope of the present application should be considered as falling within the scope of the present application.

Claims

1. A cryogenically foamed inorganic filler material, characterized in that, Comprise A component and B component, wherein: A component comprises the following raw materials by weight: cement 10-40 parts, sodium silicate 10-30 parts, dolomite 10-30 parts, foam stabilizer 1-5 parts, foaming agent 2-10 parts, surfactant 2-6 parts, water 30-60 parts; B component comprises the following raw materials by weight: organic phosphonic acid 5-15 parts, citric acid 3-10 parts, additive 5-15 parts, water 30-70 parts; The foaming agent of the A component is at least one of sodium bicarbonate, potassium bicarbonate, sodium carbonate or potassium carbonate; the foam stabilizer of the A component is nano-silicon dioxide and sodium carboxymethyl cellulose, and the mass ratio of the nano-silicon dioxide and sodium carboxymethyl cellulose is 10:1-3; The mass ratio of A component to B component is 1:

1.

2. A cryogenically expanded inorganic filler material as defined in claim 1, wherein, The cement of the A component is at least one of Portland cement, phosphate cement and aluminosilicate cement.

3. A cryogenically expanded inorganic filler material as defined in claim 1, wherein, The average particle size of the dolomite is 1-50 microns, and the modulus of the sodium silicate is 2.4-2.

8.

4. A cryogenically expanded inorganic filler material as claimed in any one of claims 1 to 3, wherein, The surfactant of the A component is one or more of Tween 80, Span 60, sodium dodecyl sulfate or sodium dodecyl benzene sulfonate.

5. A cryogenically expanded inorganic filler material as claimed in any one of claims 1 to 3, wherein the inorganic filler material is a mixture of particles of different sizes. The organic phosphonic acid of the B component is at least one of amino trimethylene phosphonic acid, hydroxy ethylene diphosphonic acid, methyl amine dimethylene phosphonic acid, glycine dimethylene phosphonic acid, ethylenediamine tetramethylene phosphonic acid and amino ethylene diphosphonic acid.

6. A cryogenically expanded inorganic filler material as claimed in any one of claims 1 to 3, wherein, The additive of the B component is at least one of water reducing agent, early strength agent and retarder.

7. A cryogenically expanded inorganic filler material as set forth in claim 6 wherein, The water reducing agent is at least one of polycarboxylic acid type water reducing agent and melamine resin type water reducing agent; the early strength agent is at least one of sodium gluconate and sodium hexametaphosphate; and the retarder is at least one of triethanolamine and sodium formate.

8. A process for the production of a cryogenically expanded inorganic filler material as claimed in any one of claims 1 to 7, characterised in that, Comprise the following steps: (1) Preparation of A component: weigh cement, sodium silicate, dolomite, foam stabilizer, foaming agent, surfactant and water by weight, put them into a stirrer, stir uniformly, and get uniform A component slurry; (2) Preparation of B component: weigh organic phosphonic acid, citric acid, additive and water by weight, put them into a stirrer, stir uniformly, and get uniform B component solution; (3) Mixed use: when used, A component and B component are mixed according to the mass ratio of 1:1, and the low-temperature foamed inorganic filling material is obtained.

9. A process for the production of a cryogenically expanded inorganic filler material according to claim 8, characterized in that The stirring speed of step (1) is 300-500 r / min, and the stirring time is 5-10 minutes; the stirring speed of step (2) is 200-400 r / min, and the stirring time is 3-8 minutes; the stirring speed of step (3) is 400-600 r / min, and the stirring time is 1-5 minutes.

10. Use of the cryogenically expanded inorganic filler material of any one of claims 1-7 and the cryogenically expanded inorganic filler material produced by the method of any one of claims 8-9 in a coal mine, comprising the steps of: A material and B material are added to the grouting system according to the mass ratio of 1:1 by using a grouting pump, and solidification filling is carried out by using a grouting machine. ​

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