Gasification slag composite inorganic guniting material and mine low-rebound high-strength support preparation process

Abstract

This invention belongs to the technical field of mine support materials and preparation processes, specifically involving a composite inorganic sprayed slurry made from gasified slag and a preparation process for low-resilience, high-strength mine support. The sprayed slurry is a pure inorganic component, composed of activated gasified slag, ordinary silicate cement, auxiliary cementitious admixtures, and functional additives in specific mass proportions. The activated gasified slag undergoes alkali activation or thermal activation treatment, without using saline wastewater. The preparation process includes gasified slag pretreatment and activation, dry powder premixing, slurry preparation, high-pressure spraying support, and natural curing. This invention achieves high-volume utilization of gasified slag, solving problems such as saline wastewater activation, the presence of organic components in the sprayed slurry, and insufficient resilience and strength in existing technologies. It is suitable for various types of mine roadway support.

Description

Technical Field

[0001] This invention belongs to the technical field of mine support materials and preparation process, specifically involving gasification slag composite inorganic sprayed grout and the preparation process of mine low-resilience high-strength support. Background Technology

[0002] Mine roadway support is a core component of ensuring safe mine production. Currently, underground support mostly uses shotcrete or ordinary inorganic grout, which suffers from problems such as high rebound rate (usually ≥15%), low early strength, and insufficient bonding strength. This not only wastes materials but also affects support efficiency and safety. Meanwhile, the coal chemical industry generates huge amounts of gasification slag, which is chemically inert, has low utilization, and long-term storage can easily lead to land occupation and environmental pollution.

[0003] In existing technologies, gasification slag is used to replace some sand and gravel in the preparation of concrete. However, some preparation processes use saline wastewater to activate the gasification slag. The introduced salt content seriously threatens the long-term durability and structural safety of the sprayed grout and brings environmental risks. This limits the applicable scenarios to a very small number of scenarios where there is no steel reinforcement, no environmental protection requirements, and no long-term durability requirements. In addition, existing sprayed grouts mostly contain organic components, which pose risks such as aging and flammability, and are not suitable for complex mining environments.

[0004] Therefore, a mine support shotcrete material with high content of gasified slag, pure inorganic, low resilience, high strength, and simple process is provided, along with a support preparation process. Summary of the Invention

[0005] To address the aforementioned shortcomings in the existing technology, this invention provides a process for preparing gasified slag composite inorganic sprayed slurry and low-resilience, high-strength support for mines, thereby solving the problems mentioned in the background technology.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The gasification slag composite inorganic spraying slurry comprises the following components in parts by weight: 50-70 parts activated gasification slag, 20-35 parts ordinary Portland cement, 5-15 parts auxiliary cementitious admixture, and 1-4 parts functional admixture; The activated gasification slag is the product obtained by crushing and screening the original gasification slag to remove impurities, grinding it to a particle size ≤0.3 mm, and then performing alkaline activation treatment or thermal activation treatment. Its main components are 40-55% silicon dioxide, 20-30% aluminum oxide, 5-12% calcium oxide, and 3-8% ferric oxide. The auxiliary cementitious admixture is a mixture of at least two of fly ash, silica fume, and desulfurized gypsum. The functional admixture is a compound system of accelerator, water-reducing agent and thickener, wherein the accelerator accounts for 0.8 to 2.0% of the total mass of the sprayed grout.

[0007] Further, the specific process of the alkaline activation treatment is as follows: using an alkaline activator composed of sodium hydroxide and water glass, taking 3-8% of the alkaline activator according to the mass of the activated gasification slag, and activating the original gasification slag with a particle size ≤0.3 mm for 24-48 h at a temperature of 25-40℃; the specific process of the thermal activation treatment is as follows: placing the original gasification slag with a particle size ≤0.3 mm into a calcination device, calcining it at a temperature of 600-800℃ for 1-2 h, and cooling it to room temperature after calcination.

[0008] Furthermore, in the auxiliary cementitious admixture, the mass ratio of fly ash, silica fume, and desulfurized gypsum is 3:2:1 to 2:2:1, wherein the specific surface area of ​​silica fume is ≥15000㎡ / kg.

[0009] Furthermore, in the functional admixture, the mass ratio of accelerator, water-reducing agent, and thickener is 5:2:1 to 4:2:1; the accelerator is an aluminate accelerator, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate ≥25%; and the thickener is hydroxypropyl methylcellulose, with a dosage of 0.1 to 0.3% of the total mass of the sprayed slurry.

[0010] This invention also includes a process for preparing low-resilience, high-strength mine support, comprising the following steps: S1: The original gasification slag is crushed, screened to remove impurities, and ground to a particle size ≤0.3 mm. Then, it is subjected to alkali activation treatment or thermal activation treatment to obtain activated gasification slag with an activity index ≥75% and a specific surface area of ​​300~500 m² / kg. S2: Activated gasification slag, ordinary silicate cement, auxiliary cementitious admixtures, and functional additives are added to the mixing equipment according to the proportions, and three-stage mixing is carried out. After being stirred evenly, premixed dry powder is obtained. S3: Add the premixed dry powder and water to the mixing equipment at a water-cement ratio of 0.22~0.28, and mix at high speed for 2~5 minutes to obtain a sprayable slurry with an initial flowability of 180~220mm; S4: The jettable slurry is sprayed in layers onto the surface of the surrounding rock of the tunnel using a jetting machine; S5: After spray molding, it is naturally cured in the mine environment for 3-7 days to form a support layer.

[0011] Furthermore, in step S2, the stirring intensity and time of the three-stage mixing are matched with the particle size and active release rate of each component: Primary mixing: The activated gasification slag and auxiliary cementitious admixture are put into the mixing equipment, the stirring speed is 300~350r / min, and the time is 5~8min. The high specific surface area of ​​the activated gasification slag preferentially coats the auxiliary cementitious admixture to form an active pre-coated structure. Secondary mixing: Add ordinary Portland cement to the mixing equipment, stir at a speed of 400~450 r / min for 8~10 min, so that the cement particles and the pre-coated structure form an interface bonding layer. Three-stage mixing: Add functional additives to the mixing equipment, stir at a speed of 400~450 r / min for 3~5 min, so that the functional additives are uniformly anchored on the particle surface.

[0012] Furthermore, in step S4, during the spraying process: The accelerator is added post-additionally at the feed inlet of the spraying machine, with a mixing time of ≤30s; The dosage of quick-setting agent is dynamically adjusted according to the surrounding rock temperature: when the surrounding rock temperature is <15℃, the dosage is 1.6~2.0% of the total mass of the shotcrete; when the surrounding rock temperature is 15~30℃, the dosage is 1.2~1.6% of the total mass of the shotcrete; when the surrounding rock temperature is >30℃, the dosage is 0.8~1.2% of the total mass of the shotcrete.

[0013] Furthermore, in step S4, the outlet of the spraying machine is cleaned every 30 to 60 minutes during the spraying process.

[0014] Furthermore, in step S5, the specific process of natural curing is as follows: within 24 hours after spraying, spray the surface of the support layer with water every 6 to 8 hours to keep it moist; after 24 hours of curing, spray clean water 2 to 3 times a day until curing is completed.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Using gasification slag as the main raw material, with a dosage of 50-70%, it significantly reduces the solid waste from coal chemical industry and decreases the environmental pollution and land occupation caused by the storage of gasification slag. At the same time, it uses alkaline activation or thermal activation processes to replace the activation of saline wastewater, avoiding secondary pollution caused by saline wastewater and reducing the amount of cement and sand used.

[0016] 2. The shotcrete material is made of pure inorganic components and does not contain organic polymers or coarse aggregates, which completely solves the hidden dangers of existing shotcrete materials containing organic components, easy aging, and flammability, and is suitable for complex mining environments.

[0017] 3. The activation process produces no saline wastewater, is environmentally friendly, and the three-stage mixing and high-pressure jetting process is easy to industrialize and promote, making it suitable for on-site mine construction personnel.

[0018] 4. Using high-volume gasified slag to replace expensive cement and sand reduces material costs compared to pure cement sprayed grout, while also reducing material rebound waste and further lowering mine support costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the preparation process of the gasification slag composite inorganic sprayed material and the low-resilience high-strength support for mines according to the present invention. Detailed Implementation

[0021] This invention provides a process for preparing composite inorganic sprayed material made from gasified slag and low-resilience, high-strength support for mines. It addresses the problems of existing sprayed materials, such as the use of saline wastewater for activation and the presence of organic components, in the preparation of sprayed materials using gasified slag. It also solves the problems of high resilience, insufficient strength, and low solid waste utilization rate of existing sprayed materials.

[0022] To achieve the above objectives, the present invention adopts the following technical solution: The gasification slag composite inorganic spraying material is composed of the following components in parts by weight: 50-70 parts activated gasification slag, 20-35 parts ordinary silicate cement, 5-15 parts auxiliary cementitious admixture, and 1-4 parts functional additives. The spraying material is a pure inorganic component, without organic polymer components or coarse aggregates. The component design completely solves the problems of existing spraying materials containing organic components, easy aging, and flammability, while reducing the rebound rate.

[0023] The activated gasification slag is a product obtained by crushing and screening the original gasification slag to remove impurities, grinding it to a particle size ≤0.3 mm, and then activating it with alkali or heat. No saline wastewater is used in the whole process to avoid secondary pollution and to activate its potential cementing activity. The main components of the activated gasification slag are 40-55% silicon dioxide, 20-30% aluminum oxide, 5-12% calcium oxide, and 3-8% ferric oxide. The loss on ignition is ≤8%, the specific surface area is 300-500 m² / kg, and the activity index is ≥75%, which ensures synergistic effect with cementing materials and improves the strength of the sprayed slurry.

[0024] The specific process of the alkali activation treatment is as follows: An alkali activator, a mixture of sodium hydroxide and water glass (mass ratio of sodium hydroxide to water glass is 1:2~1:3), is used. The activator is taken at 3~8% of the mass of the activated gasification slag. The raw gasification slag with a particle size ≤0.3 mm is activated at 25~40℃ for 24~48 hours. During activation, the slag is stirred every 8~12 hours for 5~10 minutes to ensure uniform activation. The specific process of the thermal activation treatment is as follows: The raw gasification slag with a particle size ≤0.3 mm is placed in an electrically heated calcining device. The heating rate is controlled at 5~10℃ / min, and calcined at 600~800℃ for 1~2 hours. After calcination, it is cooled to room temperature at 3~5℃ / min. The activated gasification slag needs to be tested for its activity index. An activity index ≥75% (compared to 42.5 grade ordinary Portland cement) is required. Activated gasification slag that does not meet this requirement is prohibited from use.

[0025] The auxiliary cementitious admixture is a mixture of at least two of fly ash, silica fume, and desulfurized gypsum; and the mass ratio of fly ash, silica fume, and desulfurized gypsum is 3:2:1 to 2:2:1, wherein the specific surface area of ​​silica fume is ≥15000㎡ / kg and its silica content is ≥90%; the loss on ignition of fly ash is ≤8% and its alumina content is ≥20%; the main component of desulfurized gypsum is calcium sulfate dihydrate, with a purity of ≥90% and a moisture content of ≤10%; the dosage of the auxiliary cementitious admixture can be adjusted according to the needs of mine support. When the moisture content of the surrounding rock in the mine is high, the dosage of desulfurized gypsum can be appropriately increased to improve the impermeability of the shotcrete.

[0026] The functional admixture is a compound system of accelerator, water-reducing agent, and thickener, wherein the accelerator accounts for 0.8-2.0% of the total mass of the sprayed slurry; and the mass ratio of accelerator, water-reducing agent, and thickener is 5:2:1 to 4:2:1; the accelerator is an aluminate-based accelerator, the main component of which is sodium aluminate, with a content ≥8%, an initial setting time ≤3min, a final setting time ≤20min, no chloride salt or alkali-aggregate reaction risk, and is suitable for mine corrosion prevention requirements; the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent, with a water reduction rate ≥25%, a slump retention value (30min) ≥1801mm, and does not affect the accelerator setting effect and later strength of the sprayed slurry; the thickener is hydroxypropyl methylcellulose with a molecular weight of 100,000 to 200,000, and the dosage is 0.1-0.3% of the total mass of the sprayed slurry, which can significantly improve the cohesiveness of the slurry and reduce rebound and segregation during the spraying process.

[0027] The gasified slag composite inorganic shotcrete, after being mixed with water, has an initial setting time of 1-4 minutes, a final setting time of 8-25 minutes, a shotcrete rebound rate of ≤12%, a 7-day compressive strength of ≥20MPa, and a 28-day compressive strength of ≥35MPa, meeting the strength requirements for rapid mine support; an impermeability grade of ≥P8, resisting groundwater seepage in mines; a freeze-thaw resistance grade of ≥F200, suitable for low-temperature freeze-thaw environments in mines; a softening coefficient of ≥0.85, maintaining good strength stability even in humid mine environments; a bond strength with the rock substrate of ≥0.8MPa, ensuring a tight bond between the support layer and the surrounding rock, preventing detachment; and a bulk density of 2100-2300kg / m³, with a drying shrinkage rate of ≤0.05%, avoiding later shrinkage and cracking, making it suitable for use in complex environments of mines with humid conditions, low temperatures, and requirements for seepage prevention, leak prevention, and rapid support.

[0028] Please see Figure 1 The present invention also includes a process for preparing low-resilience, high-strength mine support using the gasified slag composite inorganic sprayed grout, comprising the following steps: S1: The original gasification slag is crushed, screened to remove impurities, and ground to a particle size ≤0.3 mm. Then, it is subjected to alkali activation treatment or thermal activation treatment to obtain activated gasification slag with an activity index ≥75% and a specific surface area of ​​300~500 m² / kg. S2: Activated gasification slag, ordinary silicate cement, auxiliary cementitious admixtures, and functional additives are added to the mixing equipment according to the proportions, and three-stage mixing is carried out. After being stirred evenly, premixed dry powder is obtained. S3: Add the premixed dry powder and water to the mixing equipment at a water-cement ratio of 0.22~0.28, and mix at high speed for 2~5 minutes to obtain a sprayable slurry with an initial flowability of 180~220mm; S4: The jettable slurry is sprayed in layers onto the surface of the surrounding rock of the tunnel using a jetting machine; S5: After spray molding, it is naturally cured in the mine environment for 3-7 days to form a support layer.

[0029] Further, in step S2, the specific process of the three-stage mixing is as follows: During the first-stage mixing, activated gasification slag and auxiliary cementitious admixture are added to the mixing equipment and stirred for 5-8 minutes at a stirring speed of 300-350 r / min to ensure thorough mixing of the two raw materials; during the second-stage mixing, ordinary Portland cement is added to the mixing equipment and stirring continues for 8-10 minutes at a stirring speed of 400-450 r / min to promote uniform dispersion of the cement and the admixture; during the third-stage mixing, functional admixtures are added to the mixing equipment and stirred for 3-5 minutes at a stirring speed of 400-450 r / min until uniformly mixed, then discharged; during the mixing process, the mixing status needs to be checked every 2-3 minutes. If uneven mixing or clumping occurs, the stirring time needs to be extended; after mixing is completed, samples are taken to test the mixing uniformity. If the mixing uniformity is ≥95%, it can be used in the next step. After the premixed dry powder is discharged, it should be sealed in a moisture-proof packaging bag and stored in a dry and ventilated warehouse for no more than 72 hours. Before use, it should be checked for clumping. Clumped dry powder should be crushed and sieved before use.

[0030] Further, in step S4, the accelerator is added post-addition. After the slurry is stirred, the accelerator is added to the feed inlet of the spraying machine. The accelerator is quickly mixed with the sprayable slurry by the feed mixing device of the spraying machine (mixing time ≤30s), and then sprayed through the spraying machine. The amount of accelerator added needs to be adjusted according to the ambient temperature. When the surrounding rock temperature is <15℃, the dosage is 1.6~2.0% of the total mass of the sprayed slurry; when the surrounding rock temperature is 15~30℃, the dosage is 1.2~1.6% of the total mass of the sprayed slurry; when the surrounding rock temperature is >30℃, the dosage is 0.8~1.2% of the total mass of the sprayed slurry. During the spraying process, the discharge port of the spraying machine is cleaned every 30~60 minutes to avoid slurry clumping and clogging the pipe. After the spraying is completed, the spraying machine and the conveying pipe need to be cleaned in time and rinsed with clean water to prevent the slurry from solidifying and clogging the equipment.

[0031] Further, in step S5, the specific process for natural curing is as follows: Within 24 hours after spraying, spray clean water on the surface of the support layer every 6-8 hours to keep it moist. Use a spray pattern to avoid water flow impacting the support layer surface and causing it to detach. Before the curing period, control the temperature in the mine roadway to 5-35℃ and the humidity to ≥60%. If the humidity in the roadway is insufficient, use a spray humidifier to increase the humidity. After 24 hours of curing, spray clean water 2-3 times a day until curing is complete. During the curing period, it is forbidden to pile heavy objects on the support layer or allow it to collide with the support layer to avoid damage. If the ambient temperature is below 5℃ during the curing period, operators must cover the support layer surface with insulation felt or plastic film for insulation to prevent freeze-thaw damage.

[0032] The present invention will be further described in detail below with reference to specific embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention. In all embodiments, the raw materials used are conventional commercially available products. The gasification slag is the original gasification slag produced by coal chemical enterprises. The ordinary silicate cement is grade 42.5. The auxiliary cementitious admixtures and functional additives are all conventional products in the industry. Moreover, all raw materials are inorganic components and no organic components are added. Example 1

[0033] The composite inorganic spraying material made from gasification slag, by weight, comprises the following components: 50 parts activated gasification slag, 35 parts ordinary silicate cement, 10 parts auxiliary cementitious admixture (fly ash: silica fume: desulfurized gypsum = 3:2:1, where the fly ash is grade II, fineness 40μm, water requirement ratio 102%; silica fume specific surface area 16000m² / kg, silica content 92%; desulfurized gypsum purity 93%, moisture content 8%), and 3 parts functional admixture (accelerator: water-reducing agent: thickener = 5:2:1, where the accelerator contains 85% sodium aluminate; the water-reducing agent has a water reduction rate of 28%; the thickener has a molecular weight of 150,000). The preparation process of activated gasification slag includes: crushing and sieving the original gasification slag to remove impurities (impurity content 0.8%), grinding it to a particle size ≤0.3 mm, and leaving 4% residue on the sieve; alkali activation treatment is used: an alkali activator made of sodium hydroxide and water glass (mass ratio 1:2.5) is used, with 5% of the activated gasification slag mass as the activator. Activation is carried out at 30℃ for 36 hours, with stirring every 10 hours for 8 minutes. The main components of the activated gasification slag are 48% silicon dioxide, 25% aluminum oxide, 8% calcium oxide, and 5% ferric oxide, with a loss on ignition of 6%, a specific surface area of ​​400 m² / kg, and an activity index of 80%; the accelerator is an aluminate accelerator, used at 1.5% of the total mass of the sprayed slurry; the accelerator accounts for 1.5% of the total mass of the sprayed slurry, the water-reducing agent accounts for 1.0%, and the thickener accounts for 0.2%.

[0034] The corresponding low-resilience high-strength support preparation process for mines includes the following steps: S1: Prepare activated gasification slag according to the above-mentioned preparation process. The activity index is tested and found to be 80%, which is qualified and ready for use. S2: Add the activated gasification slag and auxiliary cementitious admixture into the mixing equipment and stir for 6 minutes (primary mixing) at a speed of 320 r / min; then add ordinary Portland cement and continue stirring for 9 minutes (secondary mixing) at a speed of 420 r / min; then add the functional admixture and stir for 4 minutes (tertiary mixing) at a speed of 420 r / min; after mixing evenly, discharge the material and check the mixing uniformity to be 96% to obtain premixed dry powder; S3: Add the premixed dry powder and water to the planetary mixer at a water-cement ratio of 0.25, control the water temperature at 25℃, first mix at low speed for 1.5 minutes (180 r / min), then mix at high speed for 2.5 minutes (450 r / min) to make a uniform sprayable slurry. The slurry flowability is tested to be 200 mm, which is qualified. S4: Clean the surface of the surrounding rock in the damp mine roadway, removing dust and loose rocks, and spray with clean water (8% moisture content); use a rotor-type spraying machine, controlling the air pressure of the spraying machine to 0.4MPa, the spraying distance to 1.0m, the spraying angle to 85°, and the spraying speed to 6m / s, using layered spraying, with each layer 40mm thick and an 8-minute interval between layers, to spray the slurry onto the surrounding rock surface under high pressure, forming a single layer with a spray thickness of 120mm; the quick-setting agent is added post-additionally at the feed inlet of the spraying machine, with a mixing time of 25s; clean the discharge port and conveying pipe of the spraying machine every 45 minutes during the spraying process; S5: After spraying, the sprayed support layer is naturally cured for 7 days in a normal mine environment (20℃) and 65% humidity. Spray clean water every 7 hours for the first 24 hours to keep it moist. After 24 hours of curing, spray clean water 3 times a day.

[0035] Performance testing: The initial setting time of this shotcrete is 2.5 min, the final setting time is 18 min, the shotcrete rebound rate is 10%, the 7-day compressive strength is 22 MPa, the 28-day compressive strength is 38 MPa, the bond strength with the rock substrate is 0.9 MPa, the impermeability grade is P8, the frost resistance grade is F200, the softening coefficient is 0.88, the drying shrinkage rate is 0.04%, and the bulk density is 2200 kg / m³. It fully meets the requirements of low-rebound high-strength support in mines, and it contains no organic components and has not been activated by saline wastewater, which meets environmental protection and mine safety requirements. Example 2

[0036] The composite inorganic spraying material made from gasification slag, by weight, comprises the following components: 60 parts activated gasification slag, 28 parts ordinary Portland cement, 10 parts auxiliary cementitious admixture (fly ash: silica fume: desulfurized gypsum = 2:2:1, where the fly ash is grade II, fineness 42μm, water requirement ratio 103%; silica fume specific surface area 15500m² / kg, silica content 91%; desulfurized gypsum purity 92%, moisture content 9%), and 2 parts functional admixture (accelerator: water-reducing agent: thickener = 4:2:1, where the accelerator has a sodium aluminate content of 82%; the water-reducing agent has a water reduction rate of 26%; the thickener has a molecular weight of 120,000). The preparation process of activated gasification slag includes: crushing and sieving the original gasification slag to remove impurities (impurity content 0.7%), grinding it to a particle size ≤0.3 mm, and leaving 3% residue on the sieve; and using thermal activation treatment: placing the ground original gasification slag into an electrically heated calcining device, controlling the heating rate at 8℃ / min, calcining it at 700℃ for 1.5 h, and then cooling it to room temperature at a rate of 4℃ / min after calcination. The main components of the activated gasification slag are 52% silicon dioxide, 23% aluminum oxide, 7% calcium oxide, and 4% ferric oxide, with a loss on ignition of 7%, a specific surface area of ​​380 m² / kg, and an activity index of 78%; the quick-setting agent accounts for 1.2% of the total mass of the sprayed slurry, the water-reducing agent accounts for 0.8%, and the thickener accounts for 0.15%.

[0037] The corresponding low-resilience high-strength support preparation process for mines includes the following steps: S1: Prepare activated gasification slag according to the above method. The activity index is tested to be 78%, which is qualified and ready for use. S2: Add the activated gasification slag and auxiliary cementitious admixture to the mixing equipment and stir for 5 minutes at a speed of 300 r / min (primary mixing); then add ordinary Portland cement and continue stirring for 8 minutes at a speed of 400 r / min (secondary mixing); then add the functional admixture and stir for 3 minutes at a speed of 400 r / min (tertiary mixing); after stirring evenly, a premixed dry powder is obtained, and the mixing uniformity is tested to be 95%. S3: Add the premixed dry powder and water to a planetary mixer at a water-cement ratio of 0.23, control the water temperature at 20℃, first mix at low speed for 1 minute (150 r / min), then mix at high speed for 2.5 minutes (400 r / min) to make a uniform sprayable slurry; the slurry flowability is tested to be 190 mm, which is qualified; S4: Clean the surface of the surrounding rock in the low-temperature tunnel of the metal mine, removing dust and loose rocks, and spray with clean water to moisten it (7% moisture content); use a rotor-type spraying machine, controlling the air pressure of the spraying machine to 0.35MPa, the spraying distance to 0.9m, the spraying angle to 80°, and the spraying speed to 5.5m / s, using layered spraying, with each layer 35mm thick and an interval of 6 minutes between layers, to spray the slurry onto the surrounding rock surface under high pressure, forming a single layer with a spray thickness of 90mm; add a quick-setting agent at the feed inlet of the spraying machine. Mixing time: 20s; ambient temperature: 12℃; appropriately increase the amount of quick-setting agent to 1.3%; clean the discharge port and conveying pipe of the spraying machine every 30 minutes during the spraying process; S5: After spraying, the sprayed support layer is naturally cured for 4 days in a normal temperature (18℃) and humidity (70%) environment in the mine. Spray water every 6 hours for the first 24 hours to keep it moist. After 24 hours of curing, spray water twice a day.

[0038] Performance testing: The initial setting time of the shotcrete is 1.8 min, the final setting time is 15 min, the shotcrete rebound rate is 11%, the 7-day compressive strength is 21 MPa, the 28-day compressive strength is 36 MPa, the bond strength with the rock substrate is 0.85 MPa, the impermeability grade is P8, the frost resistance grade is F200, the softening coefficient is 0.86, the drying shrinkage rate is 0.045%, and the bulk density is 2150 kg / m³. It fully meets the requirements of mine support, and it contains no organic components and has not been activated by saline wastewater, which meets the requirements of environmental protection and mine safety. Example 3

[0039] The composite inorganic spraying material made from gasification slag, by weight, comprises the following components: 70 parts activated gasification slag, 20 parts ordinary silicate cement, 8 parts auxiliary cementitious admixture (fly ash: silica fume = 2:1, where the fly ash is grade II, fineness 45μm, water requirement ratio 105%; silica fume specific surface area 15000m² / kg, silica content 90%), and 2 parts functional admixture (accelerator: water-reducing agent: thickener = 5:2:1, where the accelerator has a sodium aluminate content of 80%; the water-reducing agent has a water reduction rate of 25%; the thickener has a molecular weight of 200,000). The preparation process of activated gasification slag includes: crushing and sieving the original gasification slag to remove impurities (impurity content 0.9%), grinding it to a particle size ≤0.3 mm, and leaving 5% residue on the sieve; alkali activation treatment is used: an alkali activator composed of sodium hydroxide and water glass is used, with 8% of the activated gasification slag mass as the activator. Activation is carried out at 35℃ for 48 hours, with stirring every 12 hours for 10 minutes. The main components of the activated gasification slag are 45% silicon dioxide, 28% aluminum oxide, 10% calcium oxide, and 6% ferric oxide, with a loss on ignition of 8%, a specific surface area of ​​500 m² / kg, and an activity index of 75%; the quick-setting agent accounts for 2.0% of the total mass of the sprayed slurry, the water-reducing agent accounts for 0.5%, and the thickener accounts for 0.3%.

[0040] The corresponding low-resilience, high-strength support fabrication process for mines includes the following steps: S1: Prepare activated gasification slag according to the above-mentioned preparation process. The activity index is tested and found to be 75%, which is qualified and ready for use. S2: Add the activated gasification slag and auxiliary cementitious admixtures to the mixing equipment and stir for 8 minutes (primary mixing); then add ordinary Portland cement and continue stirring for 10 minutes (secondary mixing); then add the functional admixtures and stir for 5 minutes (tertiary mixing); the stirring speed is controlled at 500 r / min, and after stirring evenly, a premixed dry powder is obtained, and the mixing uniformity is tested to be 97%. S3: Add the premixed dry powder and water to the star mixer at a water-cement ratio of 0.27, control the water temperature at 28℃, and mix at high speed for 4 minutes (500 r / min) to make a uniform sprayable slurry; S4: Thoroughly clean the surface of the surrounding rock in high-gas mine roadways, removing dust, loose rocks, and oil stains, and spray with clean water to moisten (moisture content 10%); use a rotor-type spraying machine, controlling the air pressure of the spraying machine at 0.45MPa, the spraying distance at 1.1m, and the spraying angle at 90°; add a quick-setting agent to the feed inlet of the spraying machine, and after the quick-setting agent is quickly mixed with the sprayable slurry, it is sprayed onto the surface of the surrounding rock in the mine roadway through the spraying machine, using a layered spraying method, with each layer sprayed to a thickness of 40mm, an interval of 8 minutes between layers, and the spraying thickness controlled at 120mm; clean the discharge port of the spraying machine every 60 minutes during the spraying process; S5: After spraying, the sprayed support layer is naturally cured for 6 days in a normal temperature (25℃) and humidity (60%) environment in the mine. Spray water every 8 hours for the first 24 hours to keep it moist. After 24 hours of curing, spray water twice a day.

[0041] Performance testing: The initial setting time of this shotcrete is 3.2 min, the final setting time is 22 min, the shotcrete rebound rate is 12%, the 7-day compressive strength is 20 MPa, the 28-day compressive strength is 35 MPa, the bond strength with the rock substrate is 0.8 MPa, the impermeability grade is P8, the frost resistance grade is F200, the softening coefficient is 0.85, the drying shrinkage rate is 0.05%, the bulk density is 2300 kg / m³, the airtightness is excellent, there is no risk of gas leakage, and it fully meets the requirements of low rebound and high strength support in mines.

[0042] As can be seen from Examples 1-3, as the amount of activated gasification slag increased from 50 parts (Example 1) to 70 parts (Example 3), the 28-day compressive strength decreased slightly from 38 MPa to 35 MPa, and the 7-day compressive strength decreased slightly from 22 MPa to 20 MPa. However, the rebound rate was still controlled at 10%~12%, and the bond strength with the rock was still ≥0.8 MPa, fully meeting the requirements for mine support. At the same time, the amount of solid waste disposed of increased significantly, and the material cost was further reduced.

[0043] This indicates that the present invention achieves a balance between strength performance, solid waste disposal, and economic benefits within the range of 50-70 parts. When the activated gasification slag content is less than 50 parts, although the strength is slightly improved, the solid waste disposal is insufficient and the cost advantage is weakened; when the content is higher than 70 parts, the cement content is too low, leading to an imbalance in the cementitious system, and both the strength and bonding performance fail to meet the standards.

[0044] Comparative Example 1 (Unactivated gasification slag) Compared with Example 1, only the activated gasification slag was replaced with unactivated original gasification slag (the original gasification slag was ground to a particle size ≤0.3mm, without alkaline activation or thermal activation treatment, and without the use of saline wastewater). The remaining components, proportions and preparation processes were the same as in Example 1, and the same steps were followed.

[0045] The support layers formed in Comparative Example 1 and Example 1 were compared, and the results are shown in Table 1: Table 1 index Comparative Example 1 Example 1 Initial setting time 5.5min 2.5min Final freezing time 32min 18min Spray rebound rate 18% 10% 28-day compressive strength 22MPa 38MPa Bond strength with rock 0.3MPa 0.9MPa Comparative conclusion: Compared with Example 1, the support layer of Comparative Example 1 has a slower setting time, a significantly higher rebound rate, and significantly lower compressive strength and bond strength with rock. It cannot meet the requirements of low rebound and high strength support in mines. This shows that the treatment of gasification slag by alkaline activation or thermal activation (without saline wastewater) is the key to improving the performance of shotcrete. It also reflects the advantages of the activation process of this invention compared with the non-activation process, and avoids the disadvantages of saline wastewater.

[0046] Comparative Example 2 (Single Component of Auxiliary Cementitious Admixture) Compared with Example 1, the auxiliary cementitious admixture only uses fly ash (10 parts), and the other components, proportions and preparation processes are the same as in Example 1. The same steps are followed, and it is also a pure inorganic component without the use of saline wastewater for activation.

[0047] The support layers formed in Comparative Example 2 and Example 1 were compared, and the results are shown in Table 2: Table 2 index Comparative Example 2 Example 1 Initial setting time 3.0min 2.5min Final freezing time 20min 18min Spray rebound rate 15% 10% 28-day compressive strength 30MPa 38MPa Bond strength with rock 0.6MPa 0.9MPa Comparative conclusion: The performance of Comparative Example 2 is better than that of Comparative Example 1, but there is still a significant gap compared with Example 1. This shows that the multi-component compound of fly ash, silica fume and desulfurized gypsum can significantly improve the performance of sprayed slurry. At the same time, this comparative example also proves that even without changing the core design of "no organic components and no activation by saline wastewater", a single admixture will affect the performance, further highlighting the rationality of the component compound of the present invention.

[0048] Comparative Example 3 (less than 50 parts of activated gasification slag) Compared with Example 1, the activated gasification slag was adjusted to 40 parts and the ordinary silicate cement was adjusted to 45 parts, while the remaining components, proportions and preparation processes were the same as in Example 1.

[0049] The compressive strength, material cost, and solid waste disposal rate of the support layer formed in Comparative Example 3 and Example 1 are compared, and the results are shown in Table 3: Table 3 index Comparative Example 3 Example 1 28-day compressive strength 32MPa 38MPa Material costs higher lower Solid waste disposal rate 40 copies 50 copies Comparative conclusion: The activated gasification slag of Comparative Example 3 is less than 50 parts. Although the strength meets the basic requirements, it is insufficient in solid waste disposal and has a reduced cost advantage compared with Example 1. It cannot achieve the core objective of high-volume solid waste utilization of this invention.

[0050] Comparative Example 4 (more than 70 parts of activated gasification slag) Compared with Example 1, the activated gasification slag was adjusted to 80 parts and the ordinary silicate cement was adjusted to 10 parts, while the remaining components, proportions and preparation processes were the same as in Example 1.

[0051] The results of comparing the support layer formed in Comparative Example 4 with those formed in Example 1 are shown in Table 4: Table 4 index Comparative Example 4 Example 1 7-day compressive strength 12MPa 22MPa 28-day compressive strength 28MPa 38MPa rebound rate 18% 10% Bond strength with rock 0.5MPa 0.9MPa Comparative conclusion: When the activated gasification slag exceeds 70 parts, the amount of cement is insufficient, the cementitious system is unbalanced, and the early strength, later strength, and bonding performance cannot meet the requirements of mine support. This proves that the upper limit of the activated gasification slag dosage of the present invention has a criticality.

[0052] Comparative Example 5 (Accelerator dosage less than 0.8%) Compared with Example 1, the dosage of quick-setting agent was adjusted to 0.5% of the total mass of the sprayed slurry, while the remaining components, proportions and preparation process were the same as in Example 1.

[0053] The setting time and spray rebound rate of the support layers formed in Comparative Example 5 and Example 1 were compared, and the results are shown in Table 5: Table 5 index Comparative Example 5 Example 1 Initial setting time 6.5min 2.5min Final freezing time 35min 18min rebound rate 16% 10% Comparative conclusion: When the accelerator dosage is below 0.8%, the setting time exceeds the construction requirements of rapid support in the mine, and the rebound rate increases, indicating that the lower limit of accelerator dosage is necessary.

[0054] Comparative Example 6 (Accelerator dosage higher than 2.0%) Compared with Example 1, the dosage of quick-setting agent was adjusted to 2.5% of the total mass of the sprayed slurry, while the remaining components, proportions and preparation process were the same as in Example 1.

[0055] The initial setting time, compressive strength, and construction efficiency of the support layers formed in Comparative Example 6 and Example 1 are compared, and the results are shown in Table 6: Table 6 index Comparative Example 6 Example 1 Initial setting time 0.8min 2.5min 28-day compressive strength 31MPa 38MPa Spraying Frequent pipe blockage Smooth Comparative conclusion: When the accelerator dosage is higher than 2.0%, the setting is too fast, which makes the spraying process prone to pipe blockage and the strength loss in the later stage is significant (a decrease of about 18%), proving that the upper limit of the accelerator dosage is reasonable.

[0056] Comparative Example 7 (the proportion of auxiliary cementitious admixtures exceeded the range) Compared with Example 1, the ratio of fly ash: silica fume: desulfurized gypsum was adjusted to 5:1:1, while the remaining components, proportions and preparation process were the same as in Example 1.

[0057] The support layers formed in Comparative Example 7 and Example 1 were compared, and the results are shown in Table 7: Table 7 index Comparative Example 7 Example 1 Spray rebound rate 16% 10% 28-day compressive strength 32MPa 38MPa Bond strength with rock 0.55MPa 0.9MPa Comparative conclusion: When the ratio of fly ash: silica fume: desulfurized gypsum exceeds the range of 3:2:1 to 2:2:1, insufficient silica fume leads to decreased bonding performance, increased resilience, and reduced strength, proving that the compounding ratio has technical significance.

[0058] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A composite inorganic spraying material made from gasification slag, characterized in that, The components include the following parts by weight: 50-70 parts activated gasification slag, 20-35 parts ordinary Portland cement, 5-15 parts auxiliary cementitious admixture, and 1-4 parts functional admixture; The activated gasification slag is the product obtained by crushing and screening the original gasification slag to remove impurities, grinding it to a particle size ≤0.3 mm, and then performing alkaline activation treatment or thermal activation treatment. Its main components are 40-55% silicon dioxide, 20-30% aluminum oxide, 5-12% calcium oxide, and 3-8% ferric oxide. The auxiliary cementitious admixture is a mixture of at least two of fly ash, silica fume, and desulfurized gypsum. The functional admixture is a compound system of accelerator, water-reducing agent and thickener, wherein the accelerator accounts for 0.8 to 2.0% of the total mass of the sprayed grout.

2. The gasified slag composite inorganic gunniting material according to claim 1, characterized in that, The specific process of the alkaline activation treatment is as follows: an alkaline activator composed of sodium hydroxide and water glass is used, and the alkaline activator is taken at 3-8% of the mass of the activated gasification slag. The original gasification slag with a particle size ≤0.3 mm is activated for 24-48 hours at a temperature of 25-40℃. The specific process of the thermal activation treatment is as follows: the original gasification slag with a particle size ≤0.3 mm is placed in a calcination device and calcined at a temperature of 600-800℃ for 1-2 hours. After calcination, it is cooled to room temperature.

3. The gasification slag composite inorganic sprayed grout and the preparation process of low-resilience high-strength support for mines as described in claim 1, characterized in that, In the auxiliary cementitious admixture, the mass ratio of fly ash, silica fume, and desulfurized gypsum is 3:2:1 to 2:2:1, wherein the specific surface area of ​​silica fume is ≥15000㎡ / kg.

4. The gasification slag composite inorganic spraying slurry as described in claim 1, characterized in that, In the functional admixture, the mass ratio of accelerator, water-reducing agent, and thickener is 5:2:1 to 4:2:1; the accelerator is an aluminate accelerator, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate ≥25%; the thickener is hydroxypropyl methylcellulose, and the dosage is 0.1 to 0.3% of the total mass of the sprayed slurry.

5. A process for preparing low-resilience, high-strength mine support, characterized in that, The method of using the gasification slag composite inorganic spraying material as described in any one of claims 1-4 includes the following steps: S1: The original gasification slag is crushed, screened to remove impurities, and ground to a particle size ≤0.3 mm. Then, it is subjected to alkali activation treatment or thermal activation treatment to obtain activated gasification slag with an activity index ≥75% and a specific surface area of ​​300~500 m² / kg. S2: Activated gasification slag, ordinary silicate cement, auxiliary cementitious admixtures, and functional additives are added to the mixing equipment according to the proportions, and three-stage mixing is carried out. After being stirred evenly, premixed dry powder is obtained. S3: Add the premixed dry powder and water to the mixing equipment at a water-cement ratio of 0.22~0.28, and mix at high speed for 2~5 minutes to obtain a sprayable slurry with an initial flowability of 180~220mm; S4: The jettable slurry is sprayed in layers onto the surface of the surrounding rock of the tunnel using a jetting machine; S5: After spray molding, it is naturally cured in the mine environment for 3-7 days to form a support layer.

6. The preparation process for low-resilience, high-strength mine support as described in claim 5, characterized in that, In step S2, the stirring intensity and time of the three-stage mixing are matched with the particle size and active release rate of each component: Primary mixing: The activated gasification slag and auxiliary cementitious admixture are put into the mixing equipment, the stirring speed is 300~350r / min, and the time is 5~8min. The high specific surface area of ​​the activated gasification slag preferentially coats the auxiliary cementitious admixture to form an active pre-coated structure. Secondary mixing: Add ordinary Portland cement to the mixing equipment, stir at a speed of 400~450 r / min for 8~10 min, so that the cement particles and the pre-coated structure form an interface bonding layer. Three-stage mixing: Add functional additives to the mixing equipment, stir at a speed of 400~450 r / min for 3~5 min, so that the functional additives are uniformly anchored on the particle surface.

7. The process for preparing low-resilience, high-strength mine support as described in claim 5, characterized in that, In step S4, during the spraying process: The accelerator is added post-additionally at the feed inlet of the spraying machine, with a mixing time of ≤30s; The dosage of quick-setting agent is dynamically adjusted according to the surrounding rock temperature: when the surrounding rock temperature is <15℃, the dosage is 1.6~2.0% of the total mass of the shotcrete; when the surrounding rock temperature is 15~30℃, the dosage is 1.2~1.6% of the total mass of the shotcrete; when the surrounding rock temperature is >30℃, the dosage is 0.8~1.2% of the total mass of the shotcrete.

8. The process for preparing low-resilience, high-strength mine support as described in claim 5, characterized in that, In step S4, the outlet of the spraying machine is cleaned every 30 to 60 minutes during the spraying process.

9. The process for preparing low-resilience, high-strength mine support as described in claim 5, characterized in that, In step S5, the specific process of natural curing is as follows: within 24 hours after spraying, spray the surface of the support layer with water every 6 to 8 hours to keep it moist; after 24 hours of curing, spray clean water 2 to 3 times a day until curing is completed.

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