Mine safety step curing agent and application method thereof

Abstract

The invention discloses a mine safety step curing agent and an application method thereof, and relates to the field of mine safety and geotechnical engineering. The high-calcium fly ash mortar comprises the following components in percentage by weight: 40%-60% of ordinary Portland cement, 20%-35% of high-calcium fly ash, 2%-5% of high-molecular polymer latex powder, 0.5%-2% of sodium sulfate, 0.1%-0.5% of hydroxypropyl methyl cellulose ether and the balance of water. The curing agent and the sandstone are mixed and then subjected to curing treatment on a mud layer in a hook machine compaction mode, the curing agent and the sandstone are subjected to a hydration reaction and a cementation effect, a cured layer is formed after compaction, the surface hardness of the cured layer can be close to that of a C20-C25 cement concrete plate, the compressive strength is remarkably improved, and the service life of the cured layer is prolonged. The slope protection device can safely bear frequent rolling compaction of heavy mining vehicles, can bear long-term muddy water scouring test, and plays a role in stabilizing a slope. The waste sandstone in the mine site is fully utilized as the aggregate, the treatment cost of outward transportation materials and waste earthwork is reduced, main construction equipment is only a hook machine and a watering cart, the process is simple, and large special equipment is not needed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of mine safety and geotechnical engineering, and particularly relates to a mine safety step solidifying agent and an application method thereof. BACKGROUND

[0002] In the process of open-pit mining, it is necessary to excavate downward layer by layer to form a stepped operation platform. These steps are not only mining operation faces, but also important safety passages for equipment passing and personnel evacuation. However, the newly formed step surface is usually composed of loose sandstone, soil and gravel mixed by blasting and excavation, which has loose structure, poor bearing capacity and is easy to soften and flow when encountering water. Under the action of rainfall, equipment vibration and gravity, surface collapse, gully and cracking are prone to occur, which leads to the narrowing of the step width and the steepening of the slope, seriously threatening the safety production of the mine.

[0003] At present, the conventional treatment technologies for such problems mainly include: 1. Cement concrete pouring method, that is, pouring a concrete layer on the surface of the step. This method has high cost and long construction period, and needs a large amount of cement, sand and water, and it is difficult to transport and supply water in remote mines, and the concrete curing time is long, which affects the continuous production of the mine. 2. Physical rolling method, which only relies on repeated rolling of loose layers by heavy equipment. This method has a short effect and cannot change the essential properties of the material. As soon as it is washed by rain or frequently rolled by vehicles, it quickly returns to a loose state and needs to be maintained repeatedly, which has a long-term cost. 3. Soil spraying method, which is mainly used for ecological greening, and has low soil fixation strength and cannot meet the bearing capacity requirements of heavy mining vehicles.

[0004] In summary, the existing technologies have technical defects such as high cost, long construction period, insufficient strength, poor durability and frequent maintenance. It is urgent to develop a new material and technology that can use easily available materials on site to quickly form a high-strength, high-durability and anti-cracking solidified layer through a simple construction process, so as to realize one-step forming and long-term stability of the safety step. Therefore, we propose a mine safety step solidifying agent and an application method thereof to solve the problems mentioned above.

[0005] The above information disclosed in the background of the application is only used to increase the understanding of the background of the application, and therefore, it can include prior art known by those skilled in the art. SUMMARY

[0006] The purpose of the present application is to provide a mine safety step solidifying agent and an application method thereof. The solidifying agent can fully react with the sandstone on site, and through simple mechanical compaction, a solid layer with hardness close to cement board, anti-cracking and erosion resistance can be formed in a short time, which significantly improves the stability and bearing capacity of the step and reduces the maintenance cost.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a mine safety step curing agent, composed of the following components by weight percentage: 40%-60% ordinary silicate cement, 20%-35% high-calcium fly ash, 2%-5% high molecular polymer latex powder, 0.5%-2% sodium sulfate, 0.1%-0.5% hydroxypropyl methylcellulose ether, and the balance being water.

[0008] Preferably, the preferred proportions of the components are: 50% ordinary silicate cement, 28% high-calcium fly ash, 4% polymer latex powder, 1.5% sodium sulfate, 0.3% hydroxypropyl methylcellulose ether, and 16.2% water.

[0009] This invention also provides a method for preparing a curing agent for mine safety steps. The specific steps are as follows: weigh each dry powder component according to the ratio, put the weighed dry powder components into a mixer, and perform thorough mechanical stirring to mix evenly, thereby obtaining the curing agent dry powder product; package and seal the dry powder product for storage and transportation to the mine site for use.

[0010] The application method of a mine safety step hardener includes the following specific steps:

[0011] Step 1: Site Preparation

[0012] The loose layer of the mine steps that needs to be solidified is initially leveled, and large pieces of loose stone and vegetation on the surface are removed;

[0013] Step 2: Ingredients and Mixing

[0014] Prepare a slurry by mixing the prepared curing agent dry powder with water in a certain proportion. The amount of water added should be such that the curing agent slurry reaches a suitable consistency for construction. Mix the prepared curing agent slurry with the loose sandstone soil excavated on site at a weight ratio of 1:4.

[0015] Step 3: Spreading and compaction

[0016] Spread the evenly mixed material onto the leveled step surface, and use the excavator bucket or a special vibratory tamping plate to repeatedly compact the spread layer, remove air, and make the curing agent slurry in close contact with the sandstone particles to form a dense structure.

[0017] Step 4, Maintenance

[0018] After compaction, the surface is lightly watered for curing before it can be opened to traffic and accommodate pedestrians and vehicles.

[0019] Preferably, in step 2, the weight ratio of water to curing agent powder is (0.15-0.2):1.

[0020] Preferably, in step 2, the specific operation of mixing is as follows: the slurry is evenly sprayed onto the sandstone soil, and then repeatedly turned and mixed by the bucket of the excavator until the mixture is uniform in color and free of dry material or clumps.

[0021] Preferably, in step 3, the laying thickness is 20-40cm.

[0022] Preferably, in step 4, the curing time is no less than 24 hours.

[0023] Preferably, the application method is used in the construction of mine safety platforms to achieve overall solidification of the steps.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention uses a curing agent mixed with sandstone and then compacted by an excavator to cure the mud layer. The curing agent reacts with the sandstone through hydration and bonding, and after compaction, a cured layer is formed. Its surface hardness is close to that of C20-C25 cement concrete slabs, and its compressive strength is significantly improved. It can safely withstand the frequent rolling of heavy mining vehicles and withstand long-term mud and water erosion, thus playing a role in stabilizing the slope.

[0026] 2. The organic network structure formed by the high molecular polymer added to the curing agent of the present invention endows the cured layer with good flexibility and tensile deformation resistance, which can effectively resist the stress caused by uneven settlement of the foundation and temperature changes, and prevent cracking; the dense structure and the waterproof properties of the polymer film make the cured layer have extremely strong resistance to rainwater erosion and anti-sedimentation, and can withstand the test of long-term wind and rain erosion, maintaining slope stability.

[0027] 3. This invention makes full use of the waste sandstone at the mine site as aggregate, reducing the cost of transporting materials and handling waste soil and rock. The main construction equipment is only an excavator and a water truck. The process is simple, no large special equipment is required, and the construction speed is fast, which can achieve "construction on the same day and opening to traffic the next day", greatly shortening the construction period.

[0028] 4. The curing agent of this invention makes extensive use of industrial by-products such as fly ash, realizing the resource utilization of waste. The continuous hydration of cement and the pozzolanic effect of fly ash cause the strength of the solidified body to slowly increase over time, realizing the "one-time molding and long-term stability" of the safety step, which greatly reduces the later maintenance costs and safety hazards. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0030] Figure 1 This is a schematic diagram of the application method of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Example 1:

[0033] A mine safety step curing agent is composed of the following components by weight percentage: 40%-60% ordinary silicate cement, 20%-35% high-calcium fly ash, 2%-5% high molecular polymer latex powder, 0.5%-2% sodium sulfate, 0.1%-0.5% hydroxypropyl methylcellulose ether, and the balance being water.

[0034] In one embodiment of the present invention, the preferred proportions of the components are: 50% ordinary silicate cement, 28% high-calcium fly ash, 4% polymer latex powder, 1.5% sodium sulfate, 0.3% hydroxypropyl methylcellulose ether, and 16.2% water.

[0035] Ordinary silicate cement, as the main cementing material, provides the main early and late strength and is the core of the hydration reaction with sandstone particles.

[0036] High-calcium fly ash serves two purposes: firstly, as an inexpensive filler and micro-aggregate, it reduces material costs; secondly, its active components, such as active SiO2 and Al2O3, can undergo a secondary "volcanic ash reaction" with the cement hydration product Ca(OH)2, generating more cementitious substances and significantly improving later-stage strength and durability.

[0037] High-molecular-weight polymer latex powder, as the core modifying component, forms a polymer film in the hydration system, intertwining with cement hydration products to form an "organic-inorganic" composite network structure. This greatly improves the flexibility, tensile strength, and impact resistance of the cured body, effectively inhibits cracking, and enhances the adhesion to sandstone particles.

[0038] Sodium sulfate, as an early strength agent, can accelerate the hydration process of cement, significantly improve the early strength of the solidified body, shorten the time to open traffic, and meet the needs of rapid production in mines.

[0039] Hydroxypropyl methylcellulose ether (HPMC), as a water-retaining agent and thickener, can reduce the rapid evaporation of water, ensuring that cement has enough water for full hydration in the field environment; at the same time, it increases the viscosity of the slurry, making it more uniformly distributed and better able to coat loose sandstone when mixed.

[0040] Example 2:

[0041] A method for preparing a mine safety step curing agent includes the following steps: weighing each dry powder component according to the ratio, putting the weighed dry powder components into a mixer, and mechanically stirring them thoroughly until they are mixed evenly to obtain the curing agent dry powder product; packaging and sealing the dry powder product for storage and transportation to the mine site for use.

[0042] Example 3:

[0043] The application method of a mine safety step hardener includes the following specific steps:

[0044] Step 1: Site Preparation

[0045] The loose layer of the mine steps that needs to be solidified is initially leveled, and large pieces of loose stone and vegetation on the surface are removed;

[0046] Step 2: Ingredients and Mixing

[0047] Prepare a slurry by mixing the prepared curing agent dry powder with water at a ratio of 1:(0.15-0.2). The amount of water added should be adjusted to achieve a suitable consistency for construction. Mix the prepared curing agent slurry with the loose sandstone soil excavated on site at a weight ratio of 1:4. The specific mixing operation is as follows: spray the slurry evenly onto the sandstone soil, and then repeatedly turn and mix it with the bucket of the excavator until the mixture is uniform in color and free of dry material or clumps.

[0048] Step 3: Spreading and compaction

[0049] Spread the evenly mixed material onto the leveled step surface to a thickness of 20-40cm. Use the excavator bucket or a special vibratory tamping plate to repeatedly compact the spread layer, remove air, and ensure that the curing agent slurry is in close contact with the sandstone particles to form a dense structure.

[0050] Step 4, Maintenance

[0051] After compaction, the surface should be lightly watered for at least 24 hours before it can be opened to traffic and accommodate the passage of people and vehicles.

[0052] Case 1:

[0053] A new safety step made of sandstone has been formed in an iron mine. The surface of the step is loose and there is a risk of collapse.

[0054] Take 1 ton of the curing agent dry powder of this invention (formula: 52% cement, 30% fly ash, 4.5% latex powder, 1.5% sodium sulfate, 0.3% cellulose ether, with the remainder being process losses). On-site, mix 1 ton of dry powder with 180 kg of water in a container to form a slurry.

[0055] Take 4 tons of loose sandstone soil from the site and spread it evenly on the open ground. Spray the above-mentioned slurry evenly on the sandstone soil, and then use the bucket of a 20-ton excavator to mix it for about 5 minutes until it is evenly mixed.

[0056] The mixture was spread on a step approximately 50 meters long and 3 meters wide, with an average thickness of 25 centimeters. The layer was repeatedly compacted using an excavator bucket, and finally the surface was smoothed with a vibratory tamper.

[0057] After 28 hours of water curing, the surface hardness reached 22 MPa (megapascals), allowing heavy mining cars to pass. After three months of multiple rainfalls, the surface remained intact, without cracks or erosion marks, fully meeting design requirements.

[0058] The following comparison and evaluation of the performance differences of the curing agent of this invention, traditional cement curing method and untreated loose sandstone in terms of mechanical strength, crack resistance, water erosion resistance and durability are carried out by simulating mine site conditions.

[0059] Experimental group (this invention): The curing agent dry powder of this invention is used, with the following proportions: 50% ordinary silicate cement, 28% high-calcium fly ash, 4% high molecular polymer latex powder, 1.5% sodium sulfate, 0.3% hydroxypropyl methylcellulose ether, and 16.2% water. It is mixed with sandstone on site at a weight ratio of 1:4, water is added to the optimal moisture content, and then compacted and molded.

[0060] Control group 1 (pure cement group): Ordinary 42.5R silicate cement was used and mixed with sandstone on site at a weight ratio of 1:9. The amount of cement used was the same as the absolute weight of the experimental group. Water was added to the optimum moisture content and then compacted.

[0061] Control Group 2 (Compacted Only): Only loose sandstone was used on-site, and water was added to the optimum moisture content before compaction with the same amount of work. This group represents the current technology that only performs physical compaction.

[0062] Control group 3 (untreated group): completely untreated loose sandstone from the field, which was only slightly leveled in a mold without any compaction or hardening treatment. This serves as a performance benchmark.

[0063] The sample preparation method is as follows:

[0064] Sufficient and representative loose sandstone was collected from the same mine and the same step, crushed and sieved to remove particles larger than 20mm, ensuring the consistency of aggregates in each group. The curing agent dry powder was prepared according to the formula described in the invention.

[0065] Weigh the curing agent, cement, and dry sandstone according to the design proportions for each group, and dry mix them in a mixer for 2 minutes until homogeneous. Then add the calculated amount of water and wet mix for another 5 minutes to ensure thorough mixing.

[0066] The optimum moisture content and maximum dry density of the mixture were determined using the heavy compaction method in the "Standard for Geotechnical Testing Methods" (GB / T 50123). The mixed mixture was then layered into molds of known volume and compacted using a static pressure method on a universal press, based on the optimum moisture content and maximum dry density, ensuring consistent compaction work across all groups. A Φ50mm x 100mm cylindrical mold was used for strength testing, and a 150mm × 150mm × 150mm cubic mold was used for erosion testing.

[0067] After demolding, the specimens are placed in a standard curing chamber (temperature 20±2℃, humidity ≥95%) and cured until the specified age.

[0068] The following performance tests were performed on each group of samples:

[0069] Unconfined compressive strength: After curing to the specified age, the cylindrical specimens were tested for compressive strength using a universal press at a loading rate of 1 mm / min. The maximum pressure value was recorded, and the compressive strength (MPa) was calculated. Five parallel samples were tested in each group, and the average value was taken.

[0070] Indirect tensile strength: Cubic specimens were used, and their tensile strength was tested on a press using a splitting fixture to evaluate crack resistance. Five parallel samples were tested in each group, and the average value was taken.

[0071] Water resistance test: After curing, the specimens are immersed in water for 48 hours. After removal, their unconfined compressive strength in the saturated state is tested and compared with the strength of specimens cured under standard conditions. The softening coefficient is calculated as follows: softening coefficient = saturated strength / dry strength. Five parallel samples are tested in each group, and the average value is taken.

[0072] Erosion resistance simulation test: A self-made erosion test apparatus was used. A cubic specimen was fixed on a 45° inclined plane, and a standard nozzle was placed 30 cm above the specimen surface. The specimen surface was continuously sprayed with water at a constant pressure of 0.1 MPa and flow rate for 2 hours. The eroded mud and water were collected, allowed to settle, dried, and weighed. The cumulative erosion loss mass (g) was calculated. Five parallel samples were tested in each group, and the average value was taken.

[0073] Wet-dry cycle test: Place the specimen in a 60℃ oven for 12 hours, then immerse it in water for 12 hours; this constitutes one cycle. Repeat the cycle 5 times, observe surface cracking and peeling, and test the strength retention rate. Five parallel samples are tested in each group, and the average value is taken.

[0074] The experimental results are shown in the table below:

[0075]

[0076]

[0077] As can be seen from the above, the experimental results clearly demonstrate the comprehensive advantages of the present invention.

[0078] The present invention exhibits significant strength advantages; the 7-day and 28-day unconfined compressive strengths of the experimental group (the present invention) are significantly higher than those of other groups. The high 7-day strength is attributed to the early-strength effect of sodium sulfate, meeting the requirements for rapid opening and passage; the high 28-day strength is attributed to the continuous effect of cement hydration and the pozzolanic effect of fly ash. Its tensile strength far exceeds that of control group 1 (pure cement group), which directly proves that the toughening and crack-resistant effect of the polymer latex powder is crucial, effectively preventing cracks in the cured layer due to shrinkage or base deformation.

[0079] The high softening coefficient indicates that the experimental group (in this invention) specimens maintain extremely high strength even in a saturated state, proving their dense structure and strong resistance to water erosion. This is because the polymer film blocks the pores and enhances the adhesion of the aggregate.

[0080] The extremely low erosion loss and high strength retention rate during wet-dry cycles clearly demonstrate the excellent resistance of the cured layer of this invention to rainwater erosion and environmental changes in humidity. This means that in the complex natural environment of open-pit mines, the cured steps formed by this invention can remain stable for a long time without frequent maintenance.

[0081] Compared to control group 2 (compacted group only), this invention achieves chemical consolidation, resulting in an order-of-magnitude improvement in performance, demonstrating the limitations of simple physical compaction.

[0082] Compared to control group 1 (pure cement group), based on the same amount of cementitious materials, this invention achieves a comprehensive improvement in strength, especially tensile strength and durability, through synergistic modification of fly ash and polymer. This proves the scientific nature of the formulation of this invention; fly ash not only reduces costs but also contributes to long-term strength; the polymer is the key to crack resistance and water resistance.

[0083] The above comparative experiments strongly verify that the mine safety step curing agent and its application method provided by this invention can prepare a cured layer with high strength, high toughness, high water resistance, and long-term stability. Its performance is comprehensively superior to traditional cement curing and simple physical compaction techniques, fully meeting the stringent requirements of mine safety steps for load-bearing capacity and durability, achieving the goal of one-time molding and long-term stability, and significantly reducing maintenance costs and safety risks.

[0084] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A mine safety step curing agent, characterized in that, It is composed of the following components by weight percentage: 40%-60% ordinary silicate cement, 20%-35% high-calcium fly ash, 2%-5% high molecular weight polymer latex powder, 0.5%-2% sodium sulfate, 0.1%-0.5% hydroxypropyl methylcellulose ether, and the balance water.

2. The mine safety step curing agent according to claim 1, characterized in that: The preferred proportions of the components are: 50% ordinary silicate cement, 28% high-calcium fly ash, 4% polymer latex powder, 1.5% sodium sulfate, 0.3% hydroxypropyl methylcellulose ether, and 16.2% water.

3. The preparation method of a mine safety step solidifying agent according to claim 1 or 2, characterized in that: The specific steps are as follows: Weigh each dry powder component according to the ratio, put the weighed dry powder components into a mixer, and mechanically stir them thoroughly until they are mixed evenly to obtain the curing agent dry powder product; package and seal the dry powder product for storage and transport it to the mine site for use.

4. The method of applying the curing agent according to claim 1 or 2, characterized in that, The specific steps are as follows: Step 1: Site Preparation The loose layer of the mine steps that needs to be solidified is initially leveled, and large pieces of loose stone and vegetation on the surface are removed; Step 2: Ingredients and Mixing Prepare a slurry by mixing the prepared curing agent dry powder with water in a certain proportion. The amount of water added should be such that the curing agent slurry reaches a suitable consistency for construction. Mix the prepared curing agent slurry with the loose sandstone soil excavated on site at a weight ratio of 1:

4. Step 3: Spreading and compaction Spread the evenly mixed material onto the leveled step surface, and use the excavator bucket or a special vibratory tamping plate to repeatedly compact the spread layer, remove air, and make the curing agent slurry in close contact with the sandstone particles to form a dense structure. Step 4, Maintenance After compaction, the surface is lightly watered for curing before it can be opened to traffic and accommodate pedestrians and vehicles.

5. The application method according to claim 4, characterized in that: In step 2, the weight ratio of water to dry curing agent powder is (0.15-0.2):

1.

6. The application method according to claim 4, characterized in that: In step 2, the specific mixing operation is as follows: the slurry is evenly sprayed onto the sandstone soil, and then repeatedly turned and mixed by the bucket of the excavator until the mixture is uniform in color and free of dry material or clumps.

7. The application method according to claim 4, characterized in that: In step 3, the thickness of the paving is 20-40cm.

8. The application method according to claim 4, characterized in that: In step 4, the curing time shall be no less than 24 hours.

9. The application method according to claim 4, characterized in that: The application method is used in the construction of mine safety platforms to achieve overall solidification of the steps.

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