Activated gasification slag, method for preparing the same, grouting reinforcement material and application thereof

Abstract

The application provides an activated gasification residue, a preparation method thereof, a grouting reinforcing material and application thereof. The preparation method comprises drying and screening, mechanical activation, pre-chemical activation and chemical activation. The mechanical activation comprises the following steps: first ball milling of pretreated gasification residue obtained after drying and screening to obtain primary ball-milled gasification residue; and second ball milling of the primary ball-milled gasification residue after mixing with a grinding aid to obtain mechanically activated gasification residue. The pre-chemical activation comprises the following steps: mixing the mechanically activated gasification residue with salt-containing wastewater and then heat preservation and standing. The technical scheme of the application can fundamentally solve the technical problems of high-value, large-scale utilization of gasification residue and water-softening and disintegration characteristics of soft rock in coal mine roadway.

Description

Technical Field

[0001] This invention relates to the field of mine grouting materials, and more specifically, to an activated gasification slag, its preparation method, grouting reinforcement material, and its application. Background Technology

[0002] With the extensive mining of coal resources, shallow-buried coal seams are nearing depletion, forcing coal mining to extend to deeper areas. As depth increases, ground stress intensifies, and the coal and rock mass exhibits soft rock characteristics. Simultaneously, mining activities cause damage to the coal and rock mass, leading to problems such as roadway deformation and water inrush, which are significant factors restricting safe coal mining.

[0003] Due to varying stress levels from the outside to the inside of soft rock in coal mine roadways, the degree of damage differs, resulting in changes in permeability. The seepage field within the coal and rock mass of the roadway serves not only as a channel for water and gas in fissures but also as a channel for slurry flow during the coal and rock mass control process, exhibiting strong softening and disintegration characteristics upon contact with water. As a crucial guarantee for safe coal mine production, coal mine roadway surrounding rock grouting reinforcement technology is one of the important techniques in coal mine roadway construction, playing a significant role in ensuring roadway quality and improving its safety factor. Simply put, coal mine roadway surrounding rock grouting reinforcement technology uses the surrounding rock as a foundation, employing grouting equipment to inject grout into the fissures of the surrounding rock. This leverages the filling and cementing properties of the grouting material, increasing the internal friction angle and enhancing rock mass resistance. It binds the originally loose soil particles or fractured rock fissures into a unified whole, thereby reinforcing the surrounding rock and providing it with a certain degree of stability and support, ensuring the smooth progress of coal mining.

[0004] Faced with the unique challenges of soft rock treatment in coal mine roadways, traditional cement grouting materials are increasingly unable to meet the reinforcement needs of deep underground engineering, thus limiting their development and utilization. Their main disadvantages are poor adaptability to weak surrounding rocks such as argillaceous soft rock, insufficient bonding between the grout and soft rock soil, inability to effectively wrap the argillaceous matrix, resulting in the isolation of roadway water from intrusion into deep argillaceous surrounding rocks; poor micro-expansion effect of grout hardening, unable to compensate for the auto-shrinkage and drying shrinkage caused by cement hydration; and low integrity and strength of the rock mass.

[0005] Patent CN102924019B discloses a high-strength micro-expansion grouting material and its preparation method. It uses silicate cement, sulfoaluminate cement or high-alumina cement as the base material, and mixes calcium sulfoaluminate expansion agent, quartz sand, corundum or iron tailings, organosilicon defoamer, polycarboxylate high-efficiency water-reducing agent, calcium formate or lithium carbonate, sodium gluconate, methyl cellulose ether, hydroxypropyl methyl cellulose ether or hydroxyethyl methyl cellulose ether in different weights with the base material, adds water and stirs to form grout. However, it has the problems of a wide variety of organic additives, high cost and large water demand of powder. Moreover, the grouting material produced is mainly used for grouting of high-speed railway bridge bearings, highway bridges and general building grouting, and is difficult to apply to the special geological conditions of coal mines.

[0006] While chemical grouting can achieve the desired reinforcement effect, it is costly and causes groundwater pollution with large-scale use. CN 107628789B discloses a method for preparing a rapid-setting soft rock grouting material. This method involves grafting maleate end groups onto polyethylene glycol and mixing it with toluene to obtain a modified filtrate. This filtrate is then mixed with ball-milled and sieved saline-alkali soil and deionized water, allowed to stand, and ultrasonically dispersed to obtain a dispersion. Finally, the modified filtrate, dispersion, deionized water, blast furnace slag, meta-high terephthalic acid, silicate cement, and water glass are mixed to obtain the rapid-setting soft rock grouting material. Although this method increases the active groups in the grouting material, it still suffers from low reaction efficiency, difficulty in solid-liquid separation, and low strength. The problems are particularly concerning. Modified liquids containing maleic anhydride have potential toxicity and are corrosive to equipment. The dispersion collected after treatment with the modified liquid is used directly as a stirring solution, which has adverse effects on the environment and is not suitable for operation in closed mine roadways. Although the addition of water glass can enhance the consolidation of the grout, its durability is poor in the later stage, and the grout is severely lost. At the same time, the setting time is difficult to control precisely, and the viscosity gradually increases as the grout gradually sets, which can easily clog the grouting pipe and affect the construction progress. The active groups only combine with the surface of the rock mass and cannot improve the overall strength and encapsulation of the coal and rock mass.

[0007] In general, existing grouting materials suffer from problems such as low economic and environmental benefits, inability to guarantee performance formulation, and complex preparation processes, which restrict efficient coal mine production.

[0008] Meanwhile, the development of the coal chemical industry is also hampered by the large amount of waste and waste liquid generated. To address this, this invention specifically focuses on the following three aspects: First, the 15%–20% waste residue remaining from coal gasification. Currently, the main methods for treating coarse gasification slag are stockpiling and landfilling, which not only occupy land but also cause environmental pollution. Therefore, achieving the scientific disposal of coal chemical waste and turning it into valuable resources is a crucial issue that needs to be addressed for the sustainable development of the coal gasification industry. Second, during the coal gasification process, the black water at the bottom of the gasifier quench chamber, separator, and washing tower is further concentrated through low-pressure, vacuum flash evaporation. Fine slag and clarified ash water are separated through a clarification tank and ash water pool. Some of the ash water is discharged as wastewater and sent to subsequent units for treatment and recycling. In subsequent processes of removing hardness, calcium hardness, and suspended solids, lime, NaOH, and other agents are added for softening, ultimately producing softened sludge. Currently, the main method for sludge disposal is landfilling. With technological advancements, some sludge disposal methods are shifting towards circulating fluidized bed co-firing. Polyacrylamide can also be added to dewater the sludge, forming dry sludge cakes which are then transported off-site for further treatment. Thirdly, a large amount of wastewater is generated during coal chemical production. Coal chemical wastewater undergoes a "biochemical treatment-reclaimed water reuse-membrane concentration-evaporation crystallization" process to recover a significant amount of water resources, achieving "zero discharge." In this "zero discharge" process, saline wastewater undergoes sequential chemical pretreatment for silica and hardness removal, tubular membrane microfiltration, and two-stage reverse osmosis membrane concentration. The concentrated saline wastewater is then sent to crystallizers for further concentration and crystallization, producing mixed salt solid waste. Currently, this mixed salt solid waste is primarily stored in off-site slag heaps and salt ponds, resulting in high treatment costs and environmental hazards.

[0009] Therefore, how to combine the complex environment of mines, optimize and adjust the preparation process and construction process, and at the same time take into account the recycling of coal chemical solid and liquid waste, and develop a grouting material preparation method with flexible control of setting time, high fluidity, high strength and low viscosity to meet the soft rock reinforcement grouting material needs of different application scenarios in mines, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0010] The main objective of this invention is to provide an activated gasification slag, its preparation method, a grouting reinforcement material and its application, in order to solve the problems of poor fluidity, high viscosity, uncontrollable setting time and poor mechanical properties after setting of existing reinforcement grouting materials.

[0011] To achieve the above objectives, the first aspect of the present invention provides a method for preparing activated gasification slag, the method comprising the following steps: Step S1, drying and sieving: drying the gasification slag and sieving it to obtain pretreated gasification slag with a particle size of 0.2-1 mm; Step S2, mechanical activation: subjecting the pretreated gasification slag to a first ball milling to obtain a first-milled gasification slag, mixing the first-milled gasification slag with a grinding aid and then subjecting it to a second ball milling to obtain mechanically activated gasification slag; Step S3, pre-chemical activation: mixing the mechanically activated gasification slag with saline wastewater and then keeping it at a constant temperature to obtain a mixed slurry; filtering the mixed slurry to obtain grouting water and solid particles, drying the solid particles to obtain pre-chemically activated gasification slag; SO4 in the saline wastewater 2- Concentration of 1600–1800 mg / L, Cl - The concentration is 800-1100 mg / L; Step S4, chemical activation: Prepare an activation solution, mix the pre-chemically activated gasification slag with the activation solution, keep it warm and stand, filter and dry to obtain activated gasification slag; by weight, the activation solution includes 5-15 parts of sodium acrylate, 2-5 parts of methylene diacrylamide, 0.5-1.2 parts of sodium sulfate, 0.3-1.5 parts of ammonium persulfate and 60-80 parts of water.

[0012] Further, in step S2, the rotation speed of the first ball mill is 150–200 r / min, and the time is 5–15 min; the rotation speed of the second ball mill is 200–300 r / min, and the time is 20–30 min; preferably, the specific surface area of ​​the mechanically activated gasified slag is 350–500 m². 2 / kg.

[0013] Furthermore, in step S2, the grinding aid is a softened sludge grinding aid, which is obtained by drying softened sludge and then calcining it at a temperature of 350-450°C, followed by cooling and grinding.

[0014] Furthermore, the rate of heating to the calcination temperature during calcination is 5–10 °C / min, and the holding time at the calcination temperature is 20–30 min; the grinding speed is 100–200 r / min, and the grinding time is 5–10 min.

[0015] Furthermore, in step S4, the solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution is (0.2–0.35):1.

[0016] Furthermore, in step S4, the mixing temperature is 55–70°C, the mixing time is 20–30 min, and the mixing speed is 100–120 r / min; the holding time is 60–90 min.

[0017] Further, the preparation of the activation solution in step S4 includes the following steps: Step S4-1, mixing sodium acrylate, methylene diacrylamide, sodium sulfate and a portion of water to obtain solution component A; Step S4-2, mixing ammonium persulfate with the remaining water to obtain solution component B; Step S4-3, mixing solution component B with solution component A to obtain the activation solution.

[0018] Furthermore, the preparation process of solution component A also includes dispersing the mixed system before stirring for 5 to 15 minutes; the preparation process of solution component A also includes heating the mixed system after dispersion and before stirring to 70 to 90°C; preferably, the volume ratio of solution component A to solution component B is (0.8 to 1.2):1.

[0019] Furthermore, in step S3, the solid-liquid ratio of the mechanically activated gasification slag to the saline wastewater is (0.15~0.3):1; the mixing temperature is 30~50℃, the mixing time is 10~15min; and the holding time is 18~24h.

[0020] Furthermore, sodium sulfate is added in the form of sodium sulfate miscellaneous salts, wherein the sodium sulfate content in the sodium sulfate miscellaneous salts is 75-85 wt%.

[0021] A second aspect of the present invention provides an activated gasification slag, which is prepared by the above-described method for preparing activated gasification slag.

[0022] A third aspect of the present invention provides a grouting reinforcement material, comprising, by weight: 50-70 parts of the above-mentioned activated gasification slag, 15-25 parts of silicate cement, 0.4-1.2 parts of polycarboxylate superplasticizer, 3-7 parts of anhydrous sodium carbonate, 0.8-1.5 parts of sodium lignosulfonate, 5-15 parts of softened sludge grinding aid, 10-20 parts of softened sludge calcium source activator, and 3-10 parts of sodium sulfate mixed salt.

[0023] Further, the silicate cement is P·O 52.5R silicate cement; the polycarboxylate superplasticizer is selected from one or more of HPWR-S, C1029, KSM-850 and SC-11; the sodium sulfate content in the sodium sulfate concoction is 75-85 wt%; the preparation method of the softened sludge grinding aid is as follows: after drying the softened sludge, it is first calcined at 350-450℃, cooled, and then first ground to obtain the softened sludge grinding aid; preferably, the rate of heating to the calcination temperature during calcination is 5-10℃ / min, and the holding time at the calcination temperature is... The first grinding time is 20-30 min; the first grinding speed is 100-200 r / min and the time is 5-10 min; the preparation method of the softened sludge calcium source activator is as follows: a portion of the softened sludge grinding aid is calcined at a temperature of 580-700℃ for a second time, cooled, and then ground for a second time to obtain the softened sludge calcium source activator; preferably, the holding time at the calcination temperature is 30-40 min; preferably, the second grinding speed is 200-300 r / min and the time is 5-10 min.

[0024] A fourth aspect of the present invention provides an application of the above-mentioned grouting reinforcement material in the process of soft rock reinforcement in coal chemical mines.

[0025] Furthermore, the above-mentioned grouting reinforcement material is mixed with mixing water and then grouted; preferably, the mixing water is the grouting water produced in the preparation method of activated gasified slag provided in the first aspect of the present invention.

[0026] The technical solution of this invention can fundamentally solve the technical problems of high-value and large-scale utilization of gasification slag and the softening and disintegration characteristics of soft rock in coal mine roadways upon contact with water. The method for preparing activated gasification slag can efficiently and safely dispose of coal gasification slag, miscellaneous salts, softened sludge, and saline wastewater, providing a new technical path for the high-value and large-scale utilization of coal chemical waste. The resulting activated gasification slag has high strength and self-cementing properties. When applied to grouting reinforcement materials, it can make the soft rock encased in the grouting material a solid, network-like gel whole, thus solving the problem of soft rock softening upon contact with water. Simultaneously, the grouting reinforcement material provided by this invention has a special composition, which can efficiently and safely dispose of coal gasification slag, miscellaneous salts, softened sludge, and saline wastewater, providing a new technical path for the high-value and large-scale utilization of coal chemical waste. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0028] As described in the background art, the existing reinforcement grouting materials have problems such as poor fluidity, high viscosity, uncontrollable setting time, and poor mechanical properties after setting. To solve these technical problems, the first aspect of this invention provides a method for preparing activated gasification slag, comprising the following steps: Step S1, drying and sieving: drying and sieving the gasification slag to obtain pretreated gasification slag with a particle size of 0.2–1 mm; Step S2, mechanical activation: first ball milling the pretreated gasification slag to obtain primary ball-milled gasification slag, mixing the primary ball-milled gasification slag with a grinding aid and then ball-milling it a second time to obtain mechanically activated gasification slag; Step S3, pre-chemical activation: mixing the mechanically activated gasification slag with saline wastewater and keeping it at a constant temperature to obtain a mixed slurry; filtering the mixed slurry to obtain grouting water and solid particles, drying the solid particles to obtain pre-chemically activated gasification slag; SO42- in the saline wastewater... 2- Concentration of 1600–1800 mg / L, Cl - The concentration is 800-1100 mg / L; Step S4, chemical activation: Prepare an activation solution, mix the pre-chemically activated gasification slag with the activation solution, keep it warm and stand, filter and dry to obtain activated gasification slag; by weight, the activation solution includes 5-15 parts of sodium acrylate, 2-5 parts of methylene diacrylamide, 0.5-1.2 parts of sodium sulfate, 0.3-1.5 parts of ammonium persulfate and 60-80 parts of water.

[0029] The method for preparing activated gasification slag provided by this invention can efficiently and safely dispose of coal gasification slag and softened sludge. Simultaneously, the obtained activated gasification slag possesses excellent physicochemical properties and can be used as an effective component in grouting reinforcement materials during mine surrounding rock reinforcement. Specifically, in step S1, the gasification slag to be pretreated is placed in a drying oven and dried to constant weight at (e.g., 105±5)℃, preferably with a moisture content of less than 0.5%. At the same time, gasification slag with a particle size range of 0.2–1 mm is retained, with a loss on ignition of less than 4% and low levels of powder and clay particles, exhibiting high purity and quality. This particle size distribution of the gasification slag, after modification, can be used as fine aggregate and admixture in the grouting material production process. Utilizing its micro-aggregate effect, the gasification slag plays a certain role in cementing and filling the grouting slurry. Its potential pozzolanic properties can exert its cementing effect, serving as an auxiliary cementing component, improving the overall strength of the grouting slurry, and ensuring the long-term continuous growth of the solidified body's strength.

[0030] Steps S2 to S4 designed a mechanical-pre-chemical activation-chemical activation scheme for the gasification slag to be treated. The technical effects of this scheme are mainly reflected in two aspects: First, mechanical activation increases the specific surface area of ​​the gasification slag, increases the hydration area of ​​the material, reduces the particle size of the gasification slag, forms broken bonds, defects, and lattice distortion on the surface, and provides more active reaction sites for subsequent chemical hydration. Second, chemical activation uses sodium sulfate and saline wastewater in pre-chemical activation to jointly regulate the liquid phase chemical environment, stimulate and improve the surface reaction potential energy of the gasification slag, and increase the chemical reaction activity. Adding sodium sulfate can improve the effect of the activator, reduce the surface tension of water, and enable the hydration products of the gasification slag after lattice distortion to self-cement under the action of the activator. At the same time, it reduces the amount of activation solvent and saves activation costs. As mentioned in the background section, soft rock in coal mine roadways has a strong tendency to soften and disintegrate when exposed to water. This is mainly because there are uncompensated oxygen atoms and hydroxyl groups on the surface of soft rock minerals. Under the activation scheme provided by this invention, and with the combined regulation of the liquid phase chemical environment by sodium sulfate and saline wastewater, the gasification slag can carry oxygen atoms and hydroxyl groups and complex with silicon, aluminum, and calcium ions in the soft rock. This makes the soft rock after being wrapped with grouting material a solid, network-like gel whole, thereby solving the problem of soft rock softening when exposed to water.

[0031] It is worth mentioning that the saline wastewater used in the pre-chemical activation stage of this invention contains 1600-1800 mg / L of SO4. 2- And trace amounts of Cl at 800–1100 mg / L - Using saline wastewater from coal chemical industry and sodium sulfate as activators, SO4 in the wastewater... 2- The reaction of SO42- with Ca(OH)2 in cement produces NaOH, increasing the alkalinity of the paste. 2- It can accelerate the corrosion process of mineral admixtures in gasification slag, increase the dissolution rate of low-activity components such as SiO2 and Al2O3 in the gasification slag to ensure their full reaction, accelerate the depolymerization of glass and the formation of CSH, and accelerate the hydration reaction rate, as well as reduce the concentration of SO4. 2- It can generate more hydrated calcium sulfoaluminate, which can improve the early strength of the grouting material to a certain extent, while Na + It can be chemically fixed, and can balance the negative charge of some of the gasification slag that participates in the hydration reaction process, replace the role of sodium-based bentonite, form NASH products, and promote the improvement of the mechanical strength of the matrix.

[0032] Preferably, in the preparation of pretreated gasification slag, the slag is sieved to a particle size range of 0.2-1 mm, accounting for about 65-70% of the total mass of gasification slag. Gasification slag with a particle size smaller than 0.2 mm accounts for about 15-20% of the total mass of gasification slag, with a loss on ignition greater than 8%. Gasification slag with a particle size greater than 1 mm accounts for about 10-20% of the total mass of gasification slag. The portion with a particle size range of 0.2-1 mm is then retained as pretreated gasification slag.

[0033] In a typical embodiment, in step S2, the rotation speed of the first ball mill is 150–200 r / min, and the time is 5–15 min; the rotation speed of the second ball mill is 200–300 r / min, and the time is 20–30 min. Selecting the rotation speed and time of the first and second ball mills within the above ranges allows for better mechanical activation of the gasified slag, thereby reducing its particle size and increasing its surface activity. Specifically, the milling medium in the ball milling process is steel balls, and the mass ratio of gasified slag to steel balls is 1:1. The added grinding aid has a weight fraction of 10–20% in the total ground material. Preferably, the specific surface area of ​​the mechanically activated gasified slag is 350–500 m². 2 / kg, this specific surface area can increase the hydration area of ​​the material, thereby providing more active reaction sites for subsequent chemical hydration.

[0034] Furthermore, in step S2, the grinding aid used in the mechanical activation of the second ball mill is a softened sludge grinding aid. This softened sludge grinding aid is obtained by drying softened sludge to a moisture content of less than 3%, calcining it at a temperature of 350–450°C, and then cooling and grinding it. The mineral phase of the softened sludge is calcium carbonate, specifically rhombic orthorhombic calcium carbonate crystals with a surface covered by numerous flocculent structures. After medium-temperature calcination at 350–450°C, it serves as a grinding aid, improving the grinding efficiency of gasification slag and accelerating its fracture process. Simultaneously, during subsequent chemical activation, it generates a cohesive structure through ion exchange reactions, increasing the strength of the resulting grouting material as a whole with the activated gasification slag, thereby improving the water stability of soft rock surfaces in application.

[0035] To better match the surface properties and particle size of the softened sludge grinding aid with the gasified slag obtained after the first ball milling, in a preferred embodiment, the softened sludge is heated to the calcination temperature at a rate of 5–10 °C / min, and held at the calcination temperature for 20–30 min; the grinding speed is 100–200 r / min, and the time is 5–10 min. At this heating rate and holding time, organic matter in the softened sludge can be removed more effectively; the softened sludge grinding aid after grinding at 100–200 r / min for 5–10 min can better enhance the surface activity of the gasified slag.

[0036] In a typical implementation, the solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution in step S4 is (0.2-0.35):1. Selecting the solid-liquid ratio within this range allows for more thorough contact and reaction between the metal salt ions in the activation solution and the active sites on the surface of the pre-chemically activated gasification slag, thereby enhancing the bonding effect of the obtained activated gasification slag and ultimately improving the curing effect and overall strength of the grouting reinforcement material.

[0037] To ensure more thorough chemical activation and obtain activated gasified slag with better surface activity and overall performance, thereby improving the various properties of the final grouting reinforcement material, the mixing temperature in step S4 is 55–70°C, the mixing time is 20–30 min, the mixing speed is 100–120 r / min, and the holding time is 60–90 min.

[0038] In a preferred embodiment, the preparation of the activation solution in step S4 includes the following steps: Step S4-1, mixing sodium acrylate, methylenediacrylamide, sodium sulfate, and a portion of water to obtain solution component A, with a stirring time of 10-15 min; Step S4-2, mixing ammonium persulfate with the remaining water to obtain solution component B; Step S4-3, mixing solution component B with solution component A to obtain the activation solution, with a stirring time of 10-15 min. Compared to mixing all components in the activation solution together to obtain the activation solution system, this invention divides it into two solution components, A and B, to make the resulting activation solution system more homogeneous, with uniform dispersion of each metal salt ion, thereby enhancing the chemical activation effect and improving the various properties of the activated gasification slag.

[0039] To obtain a more homogeneous activation solution, allowing for a more complete reaction between the salt additives in the activation solution and the active sites on the surface of the pre-chemically activated gasification slag, in a typical embodiment, the preparation of solution component A includes dispersing the mixture before stirring for 5–15 minutes; the preparation of solution component A also includes heating the dispersed and unstirred mixture to 70–90°C; preferably, the volume ratio of solution component A to solution component B is (0.8–1.2):1. The activation solution prepared under these conditions has a more homogeneous composition, allowing for more complete complexation between the gasification slag and its metal salt ions, thereby enhancing the chemical activation effect. This enables the gasification slag to carry oxygen atoms and hydroxyl groups, which then complex with silicon, aluminum, and calcium ions in the soft rock, forming a robust, network-like gel-like structure around the grout, ultimately better addressing the problem of softening of the grout-coated soft rock upon contact with water.

[0040] Furthermore, in step S3, the solid-liquid ratio of the mechanically activated gasification slag to the saline wastewater is (0.15–0.3):1; within this solid-liquid ratio range, the mechanically activated gasification slag and the saline wastewater can react more effectively, reducing the Cl content in the saline wastewater. - With SO4 2- It has strong diffusion ability, Cl - It reacts more easily with the clinker in cement, while SO4 2- In Ca 2+Under this action, it fully contacts the surface of the gasified slag particles, can penetrate the hydration layer on the surface of the gasified slag particles, and has an erosion interaction, providing more active reaction sites for subsequent chemical modification. In order to make the pre-chemical activation more complete, it is heated during mixing to a temperature of 30-50℃ for 10-15 minutes; and kept at this temperature for 18-24 hours. Under these conditions, the pre-chemically activated gasified slag has more active sites, thus enabling the subsequent chemical activation to proceed effectively, and ultimately improving the viscosity and mechanical properties of the resulting grouting reinforcement material.

[0041] In a typical embodiment, sodium sulfate is added in the form of sodium sulfate heterosalt, with a sodium sulfate content of 75-85 wt%. Sodium sulfate, along with other metal salt ions, plays a co-regulating role in the liquid-phase chemical environment of the system. Simultaneously, this application uses sodium sulfate heterosalt as a sodium sulfate source. Under the combined regulation of the liquid-phase chemical environment by the sodium sulfate heterosalt and saline wastewater, seed crystals are formed, accelerating the depolymerization of the glassy phase and the formation of CSH in the gasification slag. + It can be chemically fixed, and plays a role in balancing the negative charge of some of the gasification slag that participates in the hydration reaction process, replacing the role of sodium-based bentonite, and forming NASH products. While providing sodium sulfate as a component, it also realizes the treatment and recycling of miscellaneous salt solid waste. The resulting activated gasification slag has higher economic benefits than directly using sodium sulfate finished salt.

[0042] A second aspect of this invention provides an activated gasification slag, prepared by the aforementioned method. This gasification slag carries oxygen atoms and hydroxyl groups, which can complex with silicon, aluminum, and calcium ions in soft rock, promoting the formation of CSH and NASH gel products through bridging. The resulting activated gasification slag has high strength and self-cementing properties. When applied to grouting reinforcement materials, it can transform the soft rock encapsulated by the grout into a robust, network-like gel whole, effectively solving the problem of soft rock softening upon contact with water.

[0043] A third aspect of the present invention provides a grouting reinforcement material, comprising, by weight: 50-70 parts of the above-mentioned activated gasification slag, 15-25 parts of silicate cement, 0.4-1.2 parts of polycarboxylate superplasticizer, 3-7 parts of anhydrous sodium carbonate, 0.8-1.5 parts of sodium lignosulfonate, 5-15 parts of softened sludge grinding aid, 10-20 parts of softened sludge calcium source activator, and 3-10 parts of sodium sulfate mixed salt.

[0044] The grouting reinforcement material provided by this invention has certain wetting characteristics, enabling it to penetrate the surface of soft rock. It exhibits good rock mass encapsulation, solidification, and bonding properties. When combined with the aforementioned additives in the specified proportions, it addresses the problems of low strength and poor bonding in traditional grouting materials. It enhances the adhesion between the grouting material and soft rock, preventing water molecules in the grout from directly contacting the soft rock and causing softening and disintegration upon contact with water. It promotes the hydraulic reaction between the grouting material and soft rock particles, forming a high-strength, impermeable structure that encapsulates the soft rock, achieving overall solidification and forming a complete solidified body. Simultaneously, the grouting slurry undergoes micro-expansion upon hardening, compensating for the self-shrinkage and drying shrinkage caused by cement hydration. Furthermore, in-depth modification research has been conducted on the gasification slag in the formula. This addresses the problems of low solidification efficiency, low solidification strength, and secondary water seepage and softening deformation in the solidified body when traditional cement grouting materials are used for downhole soft rock treatment. On the other hand, since the modified materials used are all derived from waste products in the coal chemical production process, this not only greatly improves the green and environmentally friendly properties of the grouting material, but also facilitates the disposal of industrial solid waste, resulting in good social benefits. In particular, the softened sludge grinding aid and softened sludge calcium source activator used in this invention are both made from softened sludge, and their mineral phase is calcium carbonate. In this invention, they have two functions: First, the surface of the rhombic orthorhombic calcium carbonate crystals is covered with a large number of flocculent structures. After a period of medium-temperature calcination, they can react with the activated gasification slag through the solid-phase interface, increasing the sedimentation and growth rate of hydration products during the hydration reaction of the grouting material, thereby improving the impermeability and durability of the grouting material. Second, the calcium oxide produced after two stages of high-temperature calcination can reduce the amount of cement used in the grouting material, reduce costs, compensate for grouting material shrinkage, reduce cracking, adjust the alkalinity of the liquid phase environment of the grouting material, and improve the degree of dissolution and reaction of the gasification slag. It also eliminates the need to add sodium hydroxide separately as an alkaline activator, achieving the reinforcement effect while reducing costs.

[0045] In several typical embodiments, the silicate cement is P·O 52.5R silicate cement. Compared with other commonly used silicate cements in the art, the setting and hardening speed of P·O 52.5R silicate cement is more controllable, thereby improving the controllability of setting time when the resulting grouting reinforcement material is applied. The polycarboxylate superplasticizer is selected from one or more of HPWR-S, C1029, KSM-850 and SC-11. The sodium sulfate content in the sodium sulfate heterosalt is 75-85 wt%.

[0046] The preparation method of the softened sludge grinding aid is as follows: The softened sludge is dried to a moisture content of less than 3%, then calcined at 350–450°C, cooled, and then ground to obtain the softened sludge grinding aid. The mineral phase of the softened sludge is calcium carbonate, specifically rhombic orthorhombic calcium carbonate crystals with a large number of flocculent structures on the surface. After medium-temperature calcination at 350–450°C, it can improve the sedimentation and growth rate of hydration products during the hydration reaction of the grouting material through solid-phase interface reaction, thereby improving the impermeability and durability of the grouting material. Preferably, the heating rate to the calcination temperature is 5–10°C / min, and the holding time at the calcination temperature is 20–30 min; the first grinding speed is 100–200 r / min, and the time is 5–10 min. Calcination at this heating rate and holding time can better remove organic matter from the softened sludge; grinding at this speed and time is beneficial for further improving surface activity.

[0047] The preparation method of the softened sludge calcium source activator is as follows: A portion of the softened sludge grinding aid prepared above is subjected to a second calcination at a temperature of 580–700℃, followed by cooling and a second grinding to obtain the softened sludge calcium source activator. The softened sludge grinding aid, after high-temperature calcination at 580–700℃, decomposes to produce calcium oxide, which can reduce the amount of cement used in the grouting material, lower costs, compensate for grouting material shrinkage, reduce cracking, and adjust the alkalinity of the liquid phase environment of the grouting material, improving the dissolution and reaction degree of the gasification slag, without the need to separately add sodium hydroxide as an alkaline activator. Preferably, the holding time at the calcination temperature is 30–40 min; preferably, the second grinding speed is 200–300 r / min, and the time is 5–10 min. Selecting the parameters in the preparation process of the softened sludge calcium source activator as described above is beneficial for promoting its complete decomposition, thereby further improving the stability of the obtained grouting reinforcement material.

[0048] A fourth aspect of this invention provides an application of the above-mentioned grouting reinforcement material in the process of soft rock reinforcement in coal chemical mines. In use, the above-mentioned components are weighed and stirred evenly to form a mixture, i.e., the grouting reinforcement material. Further, the grouting reinforcement material is mixed with mixing water and then grouted. Preferably, the mixing water is the grouting water produced in the preparation method of activated gasification slag provided in the first aspect of this invention. Using this grouting water containing various salt ions as mixing water allows it to coordinate with the various components in the grouting reinforcement material, improving the grouting reinforcement effect, while simultaneously realizing the recycling of industrial waste and improving its economic benefits.

[0049] Specifically, the grouting construction technology and parameters adopted in this invention are as follows:

[0050] 1. Drilling: Grouting holes in the base plate are drilled using a pneumatic handheld drill with a Φ32mm coal drill bit. Hollow coal drill rod, hole depth 3000mm, error ±50mm, drill hole perpendicular to the bottom plate.

[0051] 2. Installation and Sealing: After drilling, install the grouting pipe and seal the hole. Before grouting, firmly connect the hollow grouting pipe to the side-type water injector. Stir the grouting material evenly in advance. Only after ensuring a safe and reliable connection can the machine be started for grouting. The specifications of the hollow grouting pipe are Φ×25×5000×3mm, with a row spacing of 1.6×2m and 4 pipes arranged in each row. The strength grade of the grouting material is ≥40MPa.

[0052] 2.1 Assemble the water injector and agitator, and connect the air and water pipes to the water injector. Rinse the mixing tank thoroughly with clean water, ensuring there are no foreign objects or hard lumps inside.

[0053] 2.2 Add a small amount of water to the mixing tank and slowly turn on the air to test run the agitator and water injector.

[0054] 2.3. The mixing and grouting can be carried out after ensuring that the agitator and water injector are operating normally, the water injected by the water injector has sufficient pressure, and all pipelines and switches are connected correctly.

[0055] 3. Ingredients

[0056] 3.1. Add mixing water to the mixing tank at a water-cement ratio of 0.3-0.5. Determine the amount of grouting material to be used based on the number of grouting holes at one time, which is 200-300 kg.

[0057] 3.2 Start the mixer, initially at a slow speed, and add the grouting material into the bucket while continuously stirring. The material must be added slowly and stirred constantly to avoid pouring a large amount of grouting material into the bucket, which would affect the mixing quality and effect.

[0058] 4. Grouting

[0059] 4.1 During grouting, grout from the outside to the inside. The grouting sequence for the bottom plate is first the middle and then the two sides. The final pressure of grouting should always be controlled between 2 and 4 MPa.

[0060] 4.2 Grouting can only begin after the water injector and grouting pipeline are in good condition and reliably connected. Slowly open the air supply valve of the water injector to start grouting. The grouting speed should be slow at the beginning, and grouting should be carried out while stirring slowly.

[0061] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0062] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0063] Example 1

[0064] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0065] 1. Weigh the raw materials according to the following proportions: 60 parts activated gasification slag; 20 parts P·O 52.5R silicate cement; 0.8 parts polycarboxylate superplasticizer HPWR-S; 5 parts anhydrous sodium carbonate; 1 part sodium lignosulfonate; 10 parts softening sludge grinding aid; 15 parts softening sludge calcium source activator; 6 parts sodium sulfate mixed salts (of which the sodium sulfate content is 80wt%). Wherein:

[0066] The preparation of activated gasification slag includes:

[0067] (1) Screen the dried gasification slag and retain the gasification slag with a particle size range of 0.2-1mm as pretreated gasification slag;

[0068] (2) The dried and softened sludge was calcined and ball-milled. The first stage of treatment was heated to 410°C at a heating rate of 8°C and held for 25 minutes. After taking out a portion and placing it at room temperature, it was ball-milled for 7 minutes at a speed of 150 r / min. The second stage was heated to 640°C and held for 35 minutes. After placing it at room temperature, it was ball-milled for 7 minutes at a speed of 260 r / min.

[0069] (3) The pretreated gasification slag obtained in step (1) was subjected to mechanical activation and chemical activation treatment respectively. The mechanical activation first stage treatment was carried out at a speed of 170 r / min and a ball milling time of 10 min. The second stage treatment added 15% grinding aid, the speed was 260 r / min, and the ball milling time was 25 min. The grinding aid was the softened sludge after calcination in the second stage treatment of step (2). The mechanically activated gasification slag after ball milling was added to the reaction vessel and then pre-chemically activated, that is, saline wastewater was added and stirred at 40℃ for 13 min to prepare a mixed solution of mechanically activated gasification slag and saline wastewater with a solid-liquid ratio of 0.18:1. The prepared mixed solution was coated and cooled to room temperature for 20 h. Finally, the gasification slag was filtered and dried to obtain pre-chemically activated gasification slag. SO4 in the saline wastewater 2- The concentration is 1700 mg / L, Cl - The concentration is 900 mg / L;

[0070] (4) The pre-chemically activated gasification slag obtained in step (3) is chemically activated. By weight, the chemical activation treatment component A consists of 10 parts sodium acrylate, 3 parts methylene diacrylamide, 0.8 parts sodium sulfate, and 40 parts water. It is dispersed for 10 min and then placed in a constant temperature water bath and heated to 80°C and stirred for 13 min. Component B consists of 1 part ammonium persulfate and 30 parts water and stirred for 13 min. After stopping the stirring, the pre-chemically activated gasification slag obtained in step (3) is added. The solid-liquid ratio of the obtained pre-chemically activated gasification slag to the activation solution is 0.3:1. After stirring for 25 min, the reaction temperature is 60°C and the rotation speed is 110 r / min. After standing and keeping warm for 75 min, it is naturally cooled to room temperature, filtered and dried to obtain the activated gasification slag.

[0071] 2. Weigh the activated gasification slag and mix it with P·O 52.5R silicate cement, polycarboxylate superplasticizer HPWR-S, anhydrous sodium carbonate, sodium lignosulfonate, sludge softening aid, sludge softening calcium source activator and sodium sulfate mixed salt in the above proportions to form a mixture. When using, put the mixture into the mixing equipment and add the salt wastewater filtrate from step (3) as the mixing water. The mixing regime is slow stirring for 3 minutes, fast stirring for 2 minutes, slow stirring for 1 minute, and a total of 6 minutes of stirring to obtain the grouting material for mine.

[0072] Example 2

[0073] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0074] 1. Weigh the raw materials according to the following proportions: 65 parts activated gasification slag; 20 parts P·O 52.5R silicate cement; 1 part polycarboxylate superplasticizer HPWR-S; 5 parts anhydrous sodium carbonate; 1.2 parts sodium lignosulfonate; 13 parts softening sludge grinding aid; 18 parts softening sludge calcium source activator; 8 parts sodium sulfate mixed salts (of which the sodium sulfate content is 83wt%). Wherein:

[0075] The preparation of activated gasification slag includes:

[0076] (1) Screen the dried gasification slag and retain the gasification slag with a particle size range of 0.2-1mm as pretreated gasification slag;

[0077] (2) The dried and softened sludge was calcined and ball-milled. The first stage of treatment was heated to 430°C at a heating rate of 10°C and held for 28 minutes. After taking out a portion and placing it at room temperature, it was ball-milled for 8 minutes at a speed of 150 r / min. The second stage was heated to 650°C and held for 35 minutes. After placing it at room temperature, it was ball-milled for 9 minutes at a speed of 280 r / min.

[0078] (3) The pretreated gasification slag obtained in step (1) was subjected to mechanical activation and chemical activation treatment respectively. The mechanical activation first stage treatment was carried out at a speed of 180 r / min and a ball milling time of 13 min. The second stage treatment added 18% grinding aid, the speed was 280 r / min, and the ball milling time was 28 min. The grinding aid was the softened sludge after calcination in the second stage treatment of step (2). The mechanically activated gasification slag after ball milling was added to the reaction vessel, and then pre-chemical activation was carried out, that is, saline wastewater was added and stirred at 45℃ for 15 min to prepare a mixed solution of mechanically activated gasification slag and saline wastewater with a solid-liquid ratio of 0.23:1. The prepared mixed solution was coated and cooled to room temperature for 22 h. Finally, the gasification slag was filtered and dried to obtain pre-chemically activated gasification slag. SO4 in the saline wastewater 2- The concentration is 1750 mg / L, Cl - The concentration is 950 mg / L;

[0079] (4) The pre-chemically activated gasification slag obtained in step (3) is chemically activated. By weight, the chemical activation treatment component A consists of 13 parts sodium acrylate, 4 parts methylene diacrylamide, 1 part sodium sulfate, and 43 parts water. It is dispersed for 13 minutes and then placed in a constant temperature water bath and heated to 85°C and stirred for 15 minutes. Component B consists of 1.3 parts ammonium persulfate and 35 parts water and stirred for 15 minutes. After stopping the stirring, the pre-chemically activated gasification slag obtained in step (3) is added. The solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution is 0.35:1. After stirring for 28 minutes, the reaction temperature is 65°C and the rotation speed is 115 r / min. After standing and keeping warm for 85 minutes, it is naturally cooled to room temperature, filtered and dried to obtain the activated gasification slag.

[0080] 2. Weigh the activated gasification slag and mix it with P·O 52.5R silicate cement, polycarboxylate superplasticizer HPWR-S, anhydrous sodium carbonate, sodium lignosulfonate, sludge softening aid, sludge softening calcium source activator and sodium sulfate mixed salt in the above proportions to form a mixture. When using, put the mixture into the mixing equipment and add the salt wastewater filtrate from step (3) as the mixing water. The mixing regime is slow stirring for 3 minutes, fast stirring for 2 minutes, slow stirring for 1 minute, and a total of 6 minutes of stirring to obtain the grouting material for mine.

[0081] Example 3

[0082] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0083] 1. Weigh the raw materials according to the following proportions: 70 parts activated gasification slag; 20 parts P·O 52.5R silicate cement; 1.2 parts polycarboxylate superplasticizer HPWR-S; 5 parts anhydrous sodium carbonate; 1.5 parts sodium lignosulfonate; 15 parts softening sludge grinding aid; 20 parts softening sludge calcium source activator; 10 parts sodium sulfate mixed salts (of which the sodium sulfate content is 85wt%). Wherein:

[0084] The preparation of activated gasification slag includes:

[0085] (1) Screen the dried gasification slag and retain the gasification slag with a particle size range of 0.2-1mm as pretreated gasification slag;

[0086] (2) The dried and softened sludge was calcined and ball-milled. In the first stage of treatment, the temperature was raised to 450°C at a rate of 10°C and held for 30 minutes. After taking out a portion and placing it at room temperature, it was ball-milled for 10 minutes at a speed of 200 r / min. In the second stage, the temperature was raised to 700°C and held for 40 minutes. After placing it at room temperature, it was ball-milled for 10 minutes at a speed of 300 r / min.

[0087] (3) The pretreated gasification slag obtained in step (1) was subjected to mechanical activation and chemical activation treatment respectively. The mechanical activation first stage treatment was carried out at a speed of 200 r / min and a ball milling time of 15 min. The second stage treatment added 20% grinding aid, the speed was 300 r / min, and the ball milling time was 30 min. The grinding aid was the softened sludge after calcination in the second stage treatment of step (2). The mechanically activated gasification slag after ball milling was added to the reaction vessel, and then pre-chemical activation was carried out, that is, saline wastewater was added and stirred at 50℃ for 15 min to prepare a mixed solution of mechanically activated gasification slag and saline wastewater with a solid-liquid ratio of 0.28:1. The prepared mixed solution was coated and cooled to room temperature for 24 h. Finally, the gasification slag was filtered and dried to obtain pre-chemically activated gasification slag. SO4 in the saline wastewater 2- The concentration is 1800 mg / L, Cl - The concentration is 1100 mg / L;

[0088] (4) The pre-chemically activated gasification slag obtained in step (3) is chemically activated. By weight, the chemical activation treatment component A consists of 15 parts sodium acrylate, 5 parts methylene diacrylamide, 1.2 parts sodium sulfate, and 45 parts water. It is dispersed for 15 minutes and then placed in a constant temperature water bath and heated to 90°C and stirred for 15 minutes. Component B consists of 1.5 parts ammonium persulfate and 35 parts water and stirred for 15 minutes. After stopping the stirring, the pre-chemically activated gasification slag obtained in step (3) is added. The solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution is 0.35:1. Stirring is stopped after 30 minutes. The reaction temperature is 70°C and the rotation speed is 120 r / min. After standing and keeping warm for 90 minutes, it is naturally cooled to room temperature. It is then filtered and dried to obtain the activated gasification slag.

[0089] 2. Weigh the activated gasification slag and mix it with P·O 52.5R silicate cement, polycarboxylate superplasticizer HPWR-S, anhydrous sodium carbonate, sodium lignosulfonate, sludge softening aid, sludge softening calcium source activator and sodium sulfate mixed salt in the above proportions to form a mixture. When using, put the mixture into the mixing equipment and add the salt wastewater filtrate from step (3) as the mixing water. The mixing regime is slow stirring for 3 minutes, fast stirring for 2 minutes, slow stirring for 1 minute, and a total of 6 minutes of stirring to obtain the grouting material for mine.

[0090] Example 4

[0091] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0092] 1. Weigh the raw materials according to the following proportions: 55 parts activated gasification slag; 20 parts P·O 52.5R silicate cement; 0.5 parts polycarboxylate superplasticizer HPWR-S; 4 parts anhydrous sodium carbonate; 0.9 parts sodium lignosulfonate; 5 parts softening sludge grinding aid; 10 parts softening sludge calcium source activator; 4 parts sodium sulfate mixed salts (of which the sodium sulfate content is 75wt%). Wherein:

[0093] (1) Screen the dried gasification slag and retain the gasification slag with a particle size range of 0.2-1mm as pretreated gasification slag;

[0094] (1) Screen the dried gasification slag and retain the gasification slag with a particle size range of 0.2-1mm;

[0095] (2) The dried and softened sludge was calcined and ball-milled. The first stage of treatment was heated to 350°C at a heating rate of 10°C and held for 30 minutes. After taking out a portion and placing it at room temperature, it was ball-milled for 5 minutes at a speed of 100 r / min. The second stage was heated to 600°C and held for 30 minutes. After placing it at room temperature, it was ball-milled for 5 minutes at a speed of 200 r / min.

[0096] (3) The pretreated gasification slag obtained in step (1) was subjected to mechanical activation and chemical activation treatment respectively. The mechanical activation first stage treatment was carried out at a speed of 150 r / min and a ball milling time of 6 min. The second stage treatment added 10% grinding aid, the speed was 200 r / min, and the ball milling time was 20 min. The grinding aid was the softened sludge after calcination in the second stage treatment of step (2). The mechanically activated gasification slag after ball milling was added to the reaction vessel, and then pre-chemical activation was carried out, that is, saline wastewater was added and stirred at 30℃ for 10 min to prepare a mixed solution of mechanically activated gasification slag and saline wastewater with a solid-liquid ratio of 0.28:1. The prepared mixed solution was coated and cooled to room temperature for 18 h. Finally, the gasification slag was filtered and dried to obtain pre-chemically activated gasification slag. SO4 in the saline wastewater 2- The concentration is 1600 mg / L, Cl -The concentration is 800 mg / L;

[0097] (4) The pre-chemically activated gasification slag obtained in step (3) is chemically activated. By weight, the chemical activation treatment component A consists of 6 parts sodium acrylate, 2 parts methylene diacrylamide, 0.5 parts sodium sulfate, and 35 parts water. It is dispersed for 5 minutes and then placed in a constant temperature water bath and heated to 70°C and stirred for 10 minutes. Component B consists of 0.3 parts ammonium persulfate and 25 parts water and stirred for 10 minutes. After stopping the stirring, the pre-chemically activated gasification slag obtained in step (3) is added. The solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution is 0.2:1. Stirring is stopped after 20 minutes. The reaction temperature is 55°C and the rotation speed is 100 r / min. After standing and keeping warm for 60 minutes, it is naturally cooled to room temperature. It is then filtered and dried to obtain the activated gasification slag.

[0098] 2. Weigh the activated gasification slag and mix it with P·O 52.5R silicate cement, polycarboxylate superplasticizer HPWR-S, anhydrous sodium carbonate, sodium lignosulfonate, sludge softening aid, sludge softening calcium source activator and sodium sulfate mixed salt in the above proportions to form a mixture. When using, put the mixture into the mixing equipment and add the salt wastewater filtrate from step (3) as the mixing water. The mixing regime is slow stirring for 3 minutes, fast stirring for 2 minutes, slow stirring for 1 minute, and a total of 6 minutes of stirring to obtain the grouting material for mine.

[0099] Example 5

[0100] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0101] The only difference between this embodiment and embodiment 1 is that in step (3) of preparing the activated gasification slag, the solid-liquid ratio in the mixed solution of the mechanically activated gasification slag and the saline wastewater is adjusted to 0.15:1.

[0102] Example 6

[0103] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0104] The only difference between this embodiment and Embodiment 1 is that in the preparation step (3) of the activated gasification slag, the solid-liquid ratio in the mixed solution of the mechanically activated gasification slag and the saline wastewater is adjusted to 0.3:1.

[0105] Example 7

[0106] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0107] The only difference between this embodiment and Embodiment 1 is that the components of the grouting reinforcement material include 0.6 parts of polycarboxylate superplasticizer, 6 parts of anhydrous sodium carbonate, 1 part of sodium lignosulfonate, 10 parts of sludge softening grinding aid, and 15 parts of sludge softening calcium source activator.

[0108] Example 8

[0109] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0110] The only difference between this embodiment and Embodiment 1 is that the grouting reinforcement material contains 0.8 parts of polycarboxylate superplasticizer, 3 parts of anhydrous sodium carbonate, 1.2 parts of sodium lignosulfonate, 10 parts of sludge softening grinding aid, and 15 parts of sludge softening calcium source activator.

[0111] Example 9

[0112] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0113] The only difference between this embodiment and Embodiment 1 is that in the second stage of ball milling in the preparation step (3) of the activated gasification slag, the added grinding aid is not a sludge softening grinding aid, but colloidal graphite.

[0114] Example 10

[0115] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0116] The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of mechanically activated gasification slag to saline wastewater in step (3) of the preparation of activated gasification slag is adjusted to 0.1:1.

[0117] Example 11

[0118] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0119] The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of mechanically activated gasification slag to saline wastewater in step (3) of the preparation of activated gasification slag is adjusted to 0.5:1.

[0120] Example 12

[0121] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0122] The only difference between this embodiment and Example 1 is that in the preparation step (4) of the activated gasification slag, the activation solution is not prepared with two solution components A and B. Instead, 13 parts of sodium acrylate, 4 parts of methylene diacrylamide, 1 part of sodium sulfate, 1.3 parts of ammonium persulfate and 78 parts of water are directly mixed, dispersed for 13 minutes, and then placed in a constant temperature water bath and heated to 85°C and stirred for 15 minutes to obtain the activation solution.

[0123] Example 13

[0124] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0125] The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution in step (4) of the preparation of activated gasification slag is 0.05:1.

[0126] Example 14

[0127] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0128] The only difference between this embodiment and embodiment 1 is that in step (4) of preparing the activated gasification slag, the solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution is 0.5:1.

[0129] Comparative Example 1

[0130] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0131] The only difference between this comparative example and Example 1 is that step (4) (chemical activation) is not included in the preparation process of the activated gasification slag; instead, mechanical activation and saline wastewater erosion activation (pre-chemical activation) are performed only in steps (2) and (3). All other steps are the same as in Example 1.

[0132] Comparative Example 2

[0133] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0134] The only difference between this comparative example and Example 1 is that in the preparation process of the activated gasification slag, steps (2) and (3) (mechanical activation and pre-chemical activation) are not included, and modification is carried out only through step (4) (chemical activation). All other aspects are the same as in Example 1.

[0135] Comparative Example 3

[0136] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0137] The only difference between this embodiment and Embodiment 1 is that the proportion of sodium sulfate mixed salt in the grouting reinforcement material formulation is adjusted to 15 parts.

[0138] Comparative Example 4

[0139] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0140] The only difference between this comparative example and Example 1 is that in the preparation step (1) of the activated gasification slag, gasification slag with a particle size of ≤0.2mm is retained as pretreated gasification slag.

[0141] Comparative Example 5

[0142] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0143] The only difference between this comparative example and Example 1 is that no grinding aid was added in the second stage of ball milling in step (3) of the preparation of activated gasification slag.

[0144] Comparative Example 6

[0145] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0146] The only difference between this comparative example and Example 1 is that in the preparation step (3) of the activated gasification slag, the chemical activation treatment component A consists of 2 parts sodium acrylate, 1 part methylene diacrylamide, 2 parts sodium sulfate, and 50 parts water; component B consists of 2 parts ammonium persulfate and 40 parts water.

[0147] Comparative Example 7

[0148] Preparation of a grouting reinforcement material and a grouting slurry for mines:

[0149] The only difference between this comparative example and Example 1 is that in the preparation step (3) of the activated gasification slag, the chemical activation treatment component A consists of 18 parts sodium acrylate, 8 parts methylene diacrylamide, 0.1 parts sodium sulfate, and 25 parts water; component B consists of 0.2 parts ammonium persulfate and 15 parts water.

[0150] Performance testing:

[0151] Initial and final setting times: The first determination was performed 30 minutes after water was added to the specimen in the moisture curing chamber. During the determination, the specimen was removed from the moisture curing chamber and placed under the needle. The needle was lowered to contact the surface of the cement paste, the screw was tightened for 1-2 seconds, and then suddenly released, allowing the needle to sink vertically and freely into the cement paste. The pointer reading was observed 30 seconds after the needle stopped sinking or after the specimen was released. When the needle sank to a depth of 4mm ± 1mm ​​from the bottom plate, the cement reached its initial setting state. The initial setting time of the cement is defined as the time from when all the cement was added to the water until it reached this initial setting state.

[0152] After determining the initial setting time, immediately remove the mold along with the cement paste from the glass plate by sliding it horizontally. Rotate it 180° so that the larger diameter end faces upwards and the smaller diameter end faces downwards, then place it back into the moisture curing chamber for continued curing. Measure every 15 minutes as the final setting time approaches. When the needle penetrates 0.5 mm into the specimen, meaning the ring-shaped attachment no longer leaves a mark, the cement has reached its final setting state. The time from when all the cement is added to the water until the final setting state is reached is the final setting time, expressed in "min". The measurement should be repeated immediately upon reaching the final setting point. Only when the two measurements are identical can the final setting state be confirmed.

[0153] Regarding the performance indicator of initial and final setting times, for the grouting material provided in this application, the optimal initial setting time is 15–50 minutes. For grouting of the roof of coal mine roadways, an excessively short initial setting time will cause the grout to lose its fluidity, clogging the grouting pipe and preventing the grout from effectively filling the fractured rock fissures and forming a relatively complete solidified body. Conversely, an excessively long initial setting time will cause the grout to drip extensively from the grouting pipe and surrounding rock fissures, resulting in waste of grout and poor filling effect on fractured rock fissures. The overall consolidation of the grout is poor; the optimal final setting time is 200–480 minutes. If the final setting time is too short, cracking may occur during the hardening process. Under normal circumstances, sufficient time is needed for full reaction and crystallization to ensure good strength and durability in the final hardened material. If the final setting time is too long, the tunnel excavation period will be extended, leading to overall project delays and increased construction costs. Furthermore, as the surrounding rock in the coal mine tunnel deforms, an excessively long final setting time can also result in insufficient early compressive strength, making grouting anchors and cables prone to damage. It should also be noted that in practical applications, the structure and properties of the rock mass vary significantly depending on the working environment, thus requiring different initial and final setting times for the grout. To address this, the grout in the embodiments provided by this invention has a wide range of initial and final setting times to meet the requirements of different rock masses with varying degrees of fracture, i.e., different working environments.

[0154] Preparation of standard specimens: Place the prepared grouting material into a cement mortar mixer, gradually add mixing water, and stir until a uniform grout is obtained. Apply a thin layer of anti-stick liquid to the inside of the mold to ensure easy removal of the specimen. Pour the mixed grout into the mold and compact it by hand or with a vibrating table to ensure the removal of air bubbles and the obtaining of a uniform, dense grout. Use a flat scraper to remove excess material from the grout surface to make it smooth. Cover the mold to prevent moisture evaporation, and then place the specimen in a constant temperature and humidity curing room for an appropriate curing time.

[0155] Mechanical strength: The prepared standard specimens were cured at 20±2℃. After demolding for 24 hours, they were cured under the same conditions for 1 day, 3 days, 7 days, and 28 days, and their compressive strength was tested. The specific testing method was as follows: Before the test, the specimens were wiped clean, their dimensions were measured, and their appearance was inspected. The specimen dimensions were measured to an accuracy of 1 mm, and the bearing area was calculated accordingly. The specimen was placed in the center of the lower platen of the testing machine. The bearing surface of the specimen should be perpendicular to the top surface during molding. The testing machine was started, and when the upper platen approached the specimen, the ball seat was adjusted to ensure even contact. The testing machine was started to apply load continuously and evenly. When the specimen approaches failure and begins to deform rapidly, the throttle of the testing machine should be stopped and adjusted until the specimen fails. Then, the failure load should be recorded. The compressive strength of the specimen is calculated by taking the arithmetic mean of the three measured values ​​as the compressive strength value of the group of specimens. If the difference between the maximum or minimum value and the median value among the three measured values ​​exceeds 15% of the median value, the maximum and minimum values ​​are discarded together, and the median value is taken as the compressive strength value of the group.

[0156] Flowability: Place the glass plate horizontally and wipe the glass plate, truncated cone mold, mixer, and mixing pot evenly with a damp cloth until their surfaces are wet but without water stains. Place the truncated cone mold in the center of the glass plate and cover it with a damp cloth. Quickly pour the mixed grout into the truncated cone mold, smooth it with a scraper, and lift the truncated cone mold vertically. Simultaneously start a stopwatch and allow the cement grout to flow on the glass plate for 30 seconds. Measure the maximum diameter of the flowing portion in two mutually perpendicular directions with a ruler, and take the average value as the flowability of the cement grout.

[0157] Viscosity: The slurry is suspended in a specific pipe liquid. Driven by an electric motor, the viscometer shaft drives the rotor to rotate, replenishing the liquid at a certain rate. When the rotor rotates in the liquid being measured, it is subjected to viscous resistance. The torque generated by the hairspring counteracts this resistance. When the torque of the hairspring and the viscous resistance torque reach equilibrium, the viscosity is calculated by comparing the change in fluid flow rate, thus obtaining the viscosity value of the substance.

[0158] The properties of the grouting reinforcement materials obtained in each embodiment and comparative example are shown in Table 1.

[0159] Table 1

[0160]

[0161]

[0162] By comparing Examples 1 and 5, 6, 10, and 11, it can be seen that the grouting reinforcement material exhibits the best performance when the solid-liquid ratio of the mechanically activated gasification slag to the saline wastewater is within the range of (0.15–0.3):1, although the endpoint values ​​decrease slightly. This is because the Cl in the saline wastewater... - With SO42- It has strong diffusion ability, Cl - It reacts more easily with the clinker in cement, while SO4 2- In Ca 2+ Under this action, it fully contacts the surface of the gasification slag particles, can penetrate the hydration layer on the surface of the gasification slag particles, and has an erosion interaction, providing more active reaction sites for subsequent chemical modification; if the solid-liquid ratio of the gasification slag and saline wastewater mixed solution is too low, it is not conducive to the reaction of various metal ions; if the solid-liquid ratio of the gasification slag and saline wastewater mixed solution is too high, the Cl- and Ca in the saline wastewater will react... 2+ It does not come into full contact with the surface of the gasification slag particles and cannot effectively penetrate the hydration layer on the surface of the gasification slag particles, thus providing more active reaction sites for subsequent chemical modification.

[0163] By comparing Examples 1 and 7 and 8, it can be seen that sodium carbonate reacts with the treated softened sludge in the grouting slurry and increases the alkalinity of the slurry liquid phase environment. At the same time, it balances the electrostatic repulsion and van der Waals forces between the polycarboxylate superplasticizer and sodium lignosulfonate and the modified gasification slag grouting slurry, so as to achieve the purpose of flexible and adjustable setting time.

[0164] Comparing Examples 1 and 9 reveals that colloidal graphite has some indirect negative effects during the cement hydration reaction. Settling during the cement hydration process leads to inhomogeneity within the grout, negatively impacting its homogeneity, integrity, and durability. Comparing Example 1 and Comparative Example 1 shows that unactivated gasification slag cannot complex with silicon, aluminum, and calcium ions in soft rock, resulting in poor interfacial bonding strength between the grout and soft rock particles, thus preventing the grout from completely encapsulating the soft rock.

[0165] By comparing Example 1 and Comparative Example 2, it can be seen that the gasification slag that has not been mechanically activated and eroded by saline wastewater has a low surface reaction potential energy, which cannot provide more active reaction sites for subsequent chemical modification, and the deagglomeration effect of the gasification slag glass is poor.

[0166] By comparing Example 1 and Comparative Example 3, it can be seen that if the sodium sulfate content in the grouting reinforcement material is too high, too much calcium vanadium will be produced in the hydration products, resulting in an excessive expansion effect, which leads to the deterioration of the strength and durability of the grouting material.

[0167] By comparing Example 1 and Comparative Example 4, it can be seen that if the particle size of the gasification slag is too small (≤0.2mm) during the preparation process, the initial and final setting times will be too long, which will seriously affect the curing and bonding effect and the actual field application.

[0168] By comparing Example 1 and Comparative Example 5, it can be seen that if no grinding aid is added during the second stage ball milling process of activated gasification slag, the strength of the resulting grouting reinforcement material decreases significantly during the later curing process.

[0169] Comparing Examples 1 and 12, and Comparative Examples 6 and 7, it is evident that an appropriate amount of sodium sulfate can promote the strength development of cement or concrete. However, excessive sodium sulfate may lead to a decrease in strength; therefore, careful control of the dosage is necessary during its use, as excessive use results in limited early-age strength improvement. Furthermore, excessive sodium sulfate can cause salt precipitation and solution concentration, negatively impacting strength development in later stages.

[0170] During the chemical activation process, as the concentrations of sodium acrylate and methylenediacrylamide increase, the number of active double bond groups in the reaction system increases, leading to accelerated sodium acrylate chain growth, an increase in the number of macromolecular chains, and a decrease in fluidity, thus causing a rapid increase in slurry viscosity. Simultaneously, under the combined regulation of the liquid-phase chemical environment by sodium sulfate and saline wastewater, seed crystals are formed, accelerating the depolymerization of glass and the formation of CSH in the gasification slag. + It can be chemically fixed, and plays a role in balancing the negative charge of some of the gasification slag that participates in the hydration reaction process. It replaces the role of sodium-based bentonite and forms NASH products. The gasification slag carries oxygen atoms and hydroxyl groups, which can complex with silicon, aluminum and calcium ions in soft rock. Under the bridging effect, it promotes the formation of CSH and NASH gel products, so that the soft rock after being wrapped by the grout becomes a solid, network gel whole, thereby solving the problem of soft rock softening when exposed to water.

[0171] As can be seen from the above description, the grouting reinforcement material for mines prepared in the above embodiments of the present invention can flexibly control the setting time while ensuring strength, and has high strength, good fluidity and low viscosity, making it suitable for grouting of the roof, floor and sidewalls of coal mine roadways.

[0172] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0173] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing activated gasification slag, characterized in that, The preparation method includes the following steps: Step S1, Drying and sieving: The gasification slag is dried and then sieved to obtain pretreated gasification slag with a particle size of 0.2~1mm; Step S2, mechanical activation: The pretreated gasification slag is first ball-milled to obtain primary ball-milled gasification slag. The primary ball-milled gasification slag is mixed with a grinding aid and then ball-milled a second time to obtain mechanically activated gasification slag. Step S3, Pre-chemical activation: The mechanically activated gasification slag is mixed with saline wastewater and kept at a constant temperature to obtain a mixed slurry; the mixed slurry is filtered to obtain grouting water and solid particles; the solid particles are dried to obtain pre-chemically activated gasification slag; the SO4 in the saline wastewater... 2- Concentration of 1600~1800 mg / L, Cl - The concentration is 800~1100 mg / L; Step S4, chemical activation: Prepare an activation solution, mix the pre-chemically activated gasification slag with the activation solution, keep it at a constant temperature and let it stand, filter and dry to obtain the activated gasification slag; by weight, the activation solution includes 5-15 parts of sodium acrylate, 2-5 parts of methylenediacrylamide, 0.5-1.2 parts of sodium sulfate, 0.3-1.5 parts of ammonium persulfate and 60-80 parts of water.

2. The method for preparing activated gasification slag according to claim 1, characterized in that, In step S2, the rotation speed of the first ball mill is 150~200 r / min and the time is 5~15 min; the rotation speed of the second ball mill is 200~300 r / min and the time is 20~30 min.

3. The method for preparing activated gasification slag according to claim 2, characterized in that, The specific surface area of ​​the mechanically activated gasified slag is 350~500 m². 2 / kg.

4. The method for preparing activated gasification slag according to any one of claims 1 to 3, characterized in that, The grinding aid mentioned in step S2 is a softened sludge grinding aid, which is obtained by drying softened sludge, calcining it at a temperature of 350~450℃, and then cooling and grinding it.

5. The method for preparing activated gasification slag according to claim 4, characterized in that, The rate at which the temperature is raised to the calcination temperature during calcination is 5~10℃ / min, and the holding time at the calcination temperature is 20~30min; the grinding speed is 100~200r / min, and the grinding time is 5~10min.

6. The method for preparing activated gasification slag according to any one of claims 1 to 3, characterized in that, In step S4, the solid-liquid ratio of the pre-chemically activated gasification slag to the activation solution is (0.2~0.35):

1.

7. The method for preparing activated gasification slag according to any one of claims 1 to 3, characterized in that, In step S4, the mixing temperature is 55~70℃, the time is 20~30min, and the rotation speed is 100~120r / min; the heat preservation and standing time is 60~90min.

8. The method for preparing activated gasification slag according to any one of claims 1 to 3, characterized in that, The preparation of the activation solution in step S4 includes the following steps: Step S4-1: The sodium acrylate, methylenediacrylamide, sodium sulfate and a portion of the water are stirred and mixed to obtain solution component A; Step S4-2: Mix the ammonium persulfate with the remaining water to obtain solution component B; Step S4-3: Mix the B solution component with the A solution component by stirring to obtain the activated solution.

9. The method for preparing activated gasification slag according to claim 8, characterized in that, The preparation process of solution component A also includes dispersing the mixed system before stirring for 5 to 15 minutes; the preparation process of solution component A also includes heating the mixed system after dispersion and before stirring to 70 to 90°C.

10. The method for preparing activated gasification slag according to claim 9, characterized in that, The volume ratio of solution component A to solution component B is (0.8~1.2):

1.

11. The method for preparing activated gasification slag according to any one of claims 1 to 3, characterized in that, In step S3, the solid-liquid ratio of the mechanically activated gasification slag to the saline wastewater is (0.15~0.3):1; the mixing temperature is 30~50℃ and the time is 10~15min; the heat preservation and standing time is 18~24h.

12. The method for preparing activated gasification slag according to claim 1, characterized in that, The sodium sulfate is added in the form of sodium sulfate miscellaneous salt, and the sodium sulfate content in the sodium sulfate miscellaneous salt is 75~85wt%.

13. An activated gasification slag, characterized in that, It is prepared by the method for preparing activated gasification slag according to any one of claims 1 to 12.

14. A grouting reinforcement material, characterized in that, By weight, the grouting reinforcement material comprises: 50-70 parts of the activated gasification slag as described in claim 13, 15-25 parts of silicate cement, 0.4-1.2 parts of polycarboxylate superplasticizer, 3-7 parts of anhydrous sodium carbonate, 0.8-1.5 parts of sodium lignosulfonate, 5-15 parts of softened sludge grinding aid, 10-20 parts of softened sludge calcium source activator, and 3-10 parts of sodium sulfate mixed salt.

15. The grouting reinforcement material according to claim 14, characterized in that, The silicate cement is P•O 52.5R silicate cement; the polycarboxylate superplasticizer is selected from one or more of HPWR-S, C1029, KSM-850 and SC-11; the sodium sulfate content in the sodium sulfate concoction is 75~85 wt%. The preparation method of the softened sludge grinding aid is as follows: after drying the softened sludge, it is first calcined at 350~450℃, cooled, and then first ground to obtain the softened sludge grinding aid. The preparation method of the softened sludge calcium source activator is as follows: a portion of the softened sludge grinding aid is calcined at a calcination temperature of 580~700℃ for a second time, and after cooling, it is ground for a second time to obtain the softened sludge calcium source activator.

16. The grouting reinforcement material according to claim 15, characterized in that, In the preparation method of the softened sludge grinding aid, the rate of heating to the calcination temperature during calcination is 5~10℃ / min, and the holding time at the calcination temperature is 20~30min; the rotation speed of the first grinding is 100~200r / min, and the time is 5~10min.

17. The grouting reinforcement material according to claim 15, characterized in that, In the preparation method of the calcium source activator for softened sludge, the holding time at the calcination temperature is 30-40 min; the rotation speed of the second grinding is 200-300 r / min, and the time is 5-10 min.

18. The application of any one of the grouting reinforcement materials according to claims 14 to 17 in the process of soft rock reinforcement in coal chemical mines.

19. The application according to claim 18, characterized in that, The grouting reinforcement material according to any one of claims 14 to 17 is mixed with mixing water and then grouted.

20. The application according to claim 19, characterized in that, The mixing water is the grouting water produced in the preparation method of activated gasification slag according to claim 1.

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