Grouting composite corrosion inhibitor for deep coal mine supporting anchor cable as well as preparation method and application of grouting composite corrosion inhibitor

Abstract

The invention relates to the technical field of corrosion inhibition additives, in particular to a composite corrosion inhibitor for a deep coal mine supporting anchor cable as well as a preparation method and application of the composite corrosion inhibitor. The invention relates to a grouting composite corrosion inhibitor for a deep coal mine support anchor cable. The grouting composite corrosion inhibitor is composed of surface-modified nano Cr2O3, Na3PO4 and surface-modified nano ZnO. Wherein Cr2O3 can form a compact oxidation film on the surface of the anchor cable, and erosion of a corrosive medium is effectively isolated; due to the adsorption-precipitation dual effects of Na3PO4, a protective phosphate film can be generated on the metal surface, and corrosion is further inhibited; and the electrochemical corrosion rate of the anchor cable is slowed down through the cathodic protection and physical barrier effects of the nano ZnO. Through the synergistic effect of structure strengthening and electrochemical coupling of the three components, the corrosion inhibitor shows excellent corrosion resistance in a deep coal mine environment. The composite corrosion inhibitor is applied to a deep mine anchoring grouting material, a novel solution is provided for deep coal resource development, and the diversity of functional products is effectively expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion inhibition additives, in particular to a composite corrosion inhibitor for deep coal mine support anchor cables, and a preparation method and application thereof. Background Art

[0002] The engineering geological environment of deep coal mines presents the typical characteristics of "three highs and one disturbance", namely the combined effect of "three highs" (high ground stress-high osmotic pressure-high temperature) and strong mining disturbance. The deformation control of the tunnel surrounding rock is highly dependent on the prestressed anchor cable support system. As a key component of deep coal mine tunnel support, the corrosion problem of anchor cables will not only reduce the overall strength of the support structure, but may also cause major safety accidents such as tunnel collapse. The complexity and harshness of the deep coal mine mining environment place extremely high demands on the durability and safety of the support structure. The deep coal mine environment is characterized by high ground stress, high humidity and multiple corrosive media. These factors work together to accelerate the corrosion process of anchor cables. High ground stress causes the anchor cables to bear greater mechanical loads, which is prone to stress corrosion cracking; the high humidity environment provides conditions for electrochemical corrosion, and media such as groundwater and condensed water come into contact with the surface of the anchor cables to form a corrosion cell; in addition, the deep coal mine environment often contains acidic gases such as H2S and CO2, as well as Cl - 、SO4 2- Corrosive ions such as ions react chemically with the anchor cable metal, causing localized corrosion, pitting, and stress corrosion cracking. As coal mining depth increases, the high ground stress, high humidity, and highly corrosive media (such as groundwater and acidic gases) in the surrounding rock of the tunnel make the corrosion problem of support materials increasingly prominent.

[0003] Existing anchor cable anti-corrosion technologies, such as surface coating, cathodic protection and traditional corrosion inhibitor addition methods, all have certain limitations in practical applications. Although surface coatings (such as epoxy resin coatings, zinc-aluminum alloy coatings, etc.) can isolate corrosive media to a certain extent, they are prone to peeling under high ground stress and mechanical wear, making it difficult to provide effective long-term protection. Cathodic protection protects anchor cables through external current or sacrificial anodes, but in deep coal mine environments, due to the complex geological environment, the installation and maintenance costs of cathodic protection systems are high and the effect is limited. Traditional corrosion inhibitors (such as molybdates, silicates, etc.) have limited corrosion inhibition effects in deep coal mine environments and may have an adverse effect on the strength of the grouting material. Therefore, the development of an anchor cable grouting corrosion inhibitor suitable for deep coal mine environments has become an important direction of current coal mine support technology research.

[0004] In recent years, composite corrosion inhibitors have garnered widespread attention in the field of metal corrosion protection due to their synergistic effects and multifunctionality. Composite corrosion inhibitors are typically composed of two or more corrosion-inhibiting components, and through the synergistic effect of these components, they can significantly enhance corrosion inhibition effectiveness. However, existing research has primarily focused on the performance of corrosion inhibitors in a single environment, while research on composite corrosion inhibitors tailored to the complex environments of deep coal mines (such as high ground stress, high humidity, and multiple corrosive media) is still lacking. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a grouting composite corrosion inhibitor for deep coal mine support anchor cables, which has high corrosion inhibition efficiency and protective performance in deep coal mine mining environments and is highly applicable and targeted.

[0006] The present invention provides a technical solution for a grouting composite corrosion inhibitor for deep coal mine support anchor cables as follows: A composite corrosion inhibitor for grouting of deep coal mine support anchor cables consists of surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO.

[0007] Preferably, the mass ratio of the surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO is 5:1-10:1-10.

[0008] This invention provides an efficient, environmentally friendly, and industrially scalable anti-corrosion solution for deep coal mine anchor grouting systems, with broad application prospects. The passivation film mechanism of Cr2O3 forms a dense oxide film on the anchor surface, effectively isolating it from corrosive media. The dual adsorption and precipitation effects of Na3PO4 chemically react with the metal surface to form a protective phosphate film, further inhibiting corrosion. The cathodic protection and physical barrier effects of nano-ZnO slow the electrochemical corrosion rate of the anchor. These three components, through a synergistic enhancement mechanism of spatial complementarity, structural reinforcement, and electrochemical coupling, enable this corrosion inhibitor to exhibit excellent corrosion resistance in deep coal mine environments.

[0009] The second purpose of the present invention is to provide a method for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables. The preparation method enhances interfacial compatibility and avoids local concentration differences through nano-milling, surface modification (silane coupling agent treatment) and ultrasonic dispersion, so that the composite corrosion inhibitor can better play its role.

[0010] The technical solution of the preparation method of a grouting composite corrosion inhibitor for deep coal mine support anchor provided by the present invention is as follows: A method for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables comprises the following steps: S1, nano-processing, ball milling Cr2O3 and ZnO powders under inert gas protection to obtain nano-Cr2O3 and nano-ZnO; S2, surface modification treatment, respectively dispersing nano-Cr2O3 and nano-ZnO in an organic solution containing a silane coupling agent, ultrasonically treating and then drying to obtain surface-modified nano-Cr2O3 and surface-modified nano-ZnO; S3. Preparation of composite corrosion inhibitor: mixing surface-modified nano-Cr2O3 and surface-modified nano-ZnO with Na3PO4 to prepare composite corrosion inhibitor.

[0011] Preferably, in step S1, Cr2O3 and ZnO powders are placed in a ball mill respectively, with zirconia balls as the medium and a ball-to-material ratio of 10:1, and ball milled at a speed of 300 rpm for 4 hours under inert gas protection to obtain nano-Cr2O3 and nano-ZnO with a particle size of ≤200 nm.

[0012] Preferably, in step S2, nano-Cr2O3 and nano-ZnO are dispersed in an ethanol solution containing 1 wt.% of a silane coupling agent, ultrasonically treated for 30 minutes, and then dried at 60°C to obtain surface-modified nano-Cr2O3 and surface-modified nano-ZnO.

[0013] The present invention nano-sizes and surface-modifies chromium oxide (Cr2O3) and zinc oxide (ZnO) powders. A high-energy ball mill is used under nitrogen protection to strictly control the ball-to-material ratio, rotation speed, and ball milling time. Combined with intermittent operation, nanoparticles with a particle size of ≤200 nm are obtained. The nanoparticles are then ultrasonically dispersed in an ethanol solution containing a silane coupling agent. After vacuum drying, the nanoparticles are characterized to confirm that the surface modification is successful.

[0014] A third object of the present invention is to provide a composite corrosion inhibitor for grouting of deep coal mine support anchor cables. This composite corrosion inhibitor is designed to address the corrosion protection requirements of deep mine anchor grouting materials, filling the technological gap in specialized corrosion inhibitors for highly mineralized underground engineering environments. This provides a novel protection solution for deep coal resource development and effectively expands the diversity of functional products. The composite corrosion inhibitor of the present invention is not only suitable for deep coal mine roadway support but can also be extended to other highly corrosive environments, such as tunnel engineering, underground engineering, and marine engineering.

[0015] The present invention provides a technical solution for the application of a grouting composite corrosion inhibitor for deep coal mine support anchor cables as follows: The invention discloses an application of a composite corrosion inhibitor for grouting of deep coal mine support anchor cables. The composite corrosion inhibitor is used in the fields of deep coal mine tunnel support, tunnel engineering, underground engineering or marine engineering.

[0016] Preferably, the composite corrosion inhibitor is used as an anchor grouting material in deep coal mine tunnels.

[0017] The fourth object of the present invention is to provide a method for using a composite corrosion inhibitor for grouting of deep coal mine support anchor cables. The composite corrosion inhibitor adopts an internal doping design, and the corrosion inhibitor is directly added to the grouting material, avoiding the problem of easy peeling of the surface coating, while ensuring that the corrosion inhibitor is evenly distributed around the anchor cable.

[0018] The present invention provides a method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables. The technical solution is as follows: A method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables comprises the following steps: (1) Surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO were uniformly added to the grouting material, and c50 ordinary Portland cement was selected as the grouting material to prepare the anchoring specimen M; (2) Add 0.2% polycarboxylate water reducer to the anchoring specimen M, inject deionized water with a water-cement ratio of 0.32, use an ultrasonic disperser for pretreatment, and then mechanically stir at a speed of 2000 rpm to form a uniform suspension; (3) The suspension is injected into a mold and compacted by vibration to form a standard specimen of 40 mm × 40 mm × 40 mm. The standard specimen is cured in a constant temperature and humidity curing room and then vacuum dried to obtain the anchor specimen G.

[0019] Preferably, in step (2), the frequency of the ultrasonic disperser is 40 kHz and the power is 500 W; in step (3), the temperature of the constant temperature and humidity curing room is 20±1°C and the relative humidity is ≥95%.

[0020] This method uses C50 ordinary Portland cement as the grouting material, employs a Cr2O3+Na3PO4+ZnO composite corrosion inhibitor system, adds a polycarboxylate superplasticizer, and adds deionized water. The mixture is then processed using an ultrasonic disperser and a high-speed mechanical mixer to ensure uniform mixing. Finally, the suspension is injected into a standard steel mold, subjected to vibration compaction, constant temperature and humidity curing, and vacuum drying to produce anchor specimen G.

[0021] Beneficial effects: (1) The present invention adopts an inorganic corrosion inhibition system (Cr2O3+Na3PO4+ZnO). Through high-energy ball milling, silane coupling agent treatment, ultrasonic dispersion, and high-speed stirring, the interfacial compatibility is enhanced, local concentration differences are avoided, and the corrosion inhibitor is better utilized. This composite corrosion inhibitor is designed to meet the corrosion protection requirements of deep mine anchoring grouting materials, filling the technical gap of specialized corrosion inhibitors for highly mineralized underground engineering environments, providing a new protection solution for deep coal resource development, and effectively expanding the diversity of functional products.

[0022] (2) The composite corrosion inhibitor of the present invention gives full play to its unique synergistic effect and multifunctional mechanism, and is verified by underground working condition simulation test. Under the high temperature, high humidity and complex ground stress coupling environment of deep coal mines, the corrosion inhibitor has an electrochemical corrosion inhibition efficiency of more than 96% on the anchor mortar, which can significantly delay the material degradation process, extend the service life of the anchor system, and effectively ensure the long-term reliability of the deep tunnel support system.

[0023] (3) The composite corrosion inhibitor adopts an internal doping design, which directly adds the corrosion inhibitor to the grouting material, avoiding the problem of easy peeling of the surface coating, while ensuring that the corrosion inhibitor is evenly distributed around the anchor cable. The composite corrosion inhibitor of the present invention is not only suitable for deep coal mine tunnel support, but can also be extended to other highly corrosive environments, such as tunnel engineering, underground engineering, marine engineering and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings and descriptions that constitute part of this application are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. Among them: Figure 1 is a flow chart; Figure 2 The figure is a comparison chart of the test results of anchor sample G1, anchor sample G2, anchor sample G3 and anchor sample CG in the compressive strength test; Figure 3 The potentiodynamic polarization curves of anchor cable specimens G1, G2, G3 and CG are shown; Figure 4 Electrochemical impedance spectra of anchor cable specimens G1, G2, G3 and CG. DETAILED DESCRIPTION

[0025] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention should fall within the scope of protection of the embodiments of the present invention.

[0026] Example 1 The preparation of the pre-treated anchor cable specimen includes the following steps: 1) A high-strength prestressed anchor cable component that meets the requirements of GB / T5224-2014 was selected. The cable component has a yield strength of 1700 MPa and an ultimate tensile strength of 2180 MPa. It is twisted with 19 steel strands and has a characteristic diameter of 22 mm after equivalent cross-section conversion.

[0027] 2) Process the base material into 10mm by wire EDM 3 Standard cubic specimens were cut and then subjected to ultrasonic cleaning (frequency 40kHz, power 120W) and constant temperature drying (105℃±2℃, continuous drying until the mass is constant).

[0028] 3) Specimen pretreatment includes conductive connection and interface packaging process: After the top of the specimen is reliably electrically connected to the copper wire, it is fixed in the special mold cavity, and the effective area of the bottom surface is controlled to be 1cm 2 , silicone is used to implement interface sealing.

[0029] 4) The working surface is treated with a fully automatic metallographic grinding equipment to implement gradient polishing: 600 mesh, 800 mesh and 1200 mesh silicon carbide sandpaper are used for staged grinding in sequence, and finally the working surface is smooth. Visual inspection shows that there are no surface defects such as oxidation pits.

[0030] 5) After the surface treatment, the test pieces were rinsed alternately with deionized water and anhydrous ethanol, transferred to a vacuum drying oven for drying (60°C), and finally packaged in a vacuum storage device with an argon atmosphere for use.

[0031] Example 2 A method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables (preparation of anchor sample G1 and anchor cable specimen G1) comprises the following steps: S1. Nano-processing: Cr2O3 and ZnO powders were placed in a high-energy ball mill using 5mm diameter zirconia balls as the medium, with a strictly controlled ball-to-material ratio of 10:1. Under nitrogen protection (purity ≥99.99%), the milling was carried out at 300 rpm for 4 hours to obtain nano-Cr2O3 and nano-ZnO powders with a particle size of ≤200 nm. During the milling process, a 10-minute pause was taken every 30 minutes to avoid local overheating and ensure the uniformity and stability of the nanoparticles.

[0032] S2. Surface modification: Nano-Cr2O3 powder and nano-ZnO powder were separately dispersed in 60 ml of an ethanol solution (95%) containing 1 wt.% of a silane coupling agent (KH-550). Ultrasonic treatment was then performed for 30 minutes using an ultrasonic cleaner (200 W power, 40 kHz frequency) to ensure adequate dispersion and surface modification of the particles. Subsequently, the suspensions were dried in a vacuum drying oven at 60°C (vacuum degree ≤ 0.1 MPa) for 12 hours to obtain surface-modified nano-Cr2O3 powder and surface-modified nano-ZnO powder, respectively.

[0033] S3, corrosion inhibitor composite and gradient dispersion, according to Table 1, respectively weighed surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO, selected c50 ordinary Portland cement as grouting material, made anchoring sample M1.

[0034] 0.2% polycarboxylate superplasticizer was added to anchor specimen M1, followed by deionized water, with a water-cement ratio strictly controlled at 0.32. The mixture was pretreated for 20 minutes using an ultrasonic disperser (frequency 40 kHz, power 500 W), followed by stirring for 1 hour using a high-speed mechanical stirrer (speed 2000 rpm) to form a uniform suspension. The dispersion of the suspension was monitored using a laser particle size analyzer to ensure uniform particle distribution and the absence of agglomerates.

[0035] S4, grouting molding and curing, inject the suspension into a standard steel mold of 40mm×40mm×40mm, use a vibration table (frequency 50Hz, amplitude 0.5mm) to vibrate and compact for 2 minutes to expel bubbles in the slurry. After molding, place the standard specimen in a constant temperature and humidity curing room (temperature 20±1℃, relative humidity ≥95%) for curing for 7 days. During the curing process, check the humidity and temperature of the specimen regularly every day to ensure that the curing environment is stable. After curing, place the specimen in a vacuum drying oven (vacuum degree ≤0.1MPa) and dry it for 24 hours to obtain the anchor specimen G1. The specimen is subjected to a compressive strength tester to test its compressive strength to ensure that its mechanical properties meet the requirements. The process is as follows Figure 1 shown.

[0036] S5. Crushing and Immersion: Crushing the 7-day-old anchor specimen G1. 300 g of the crushed sample with a particle size ≤5 mm was placed in a sealed extraction container. 500 ml of deionized water was added at a solid-to-liquid ratio of 1:1.67. The sample was shaken and immersed for 48 hours (2 Hz) at a constant temperature of 25°C. The simulated pore fluid was filtered through a 0.45 μm filter membrane to obtain the simulated pore fluid. The pretreated anchor specimen was immersed in the extraction solution for 48 hours to establish the contact interface with the corrosive medium. Anchor specimen G1 was prepared and transferred to an argon atmosphere for storage for subsequent Tafel polarization curve and electrochemical impedance spectroscopy testing.

[0037] Table 1 is the formula of composite corrosion inhibitor for anchor grouting in the embodiment Example 3 A method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables (preparation of anchor sample G2) comprises the following steps: S1. Nano-crushing: Cr2O3 and ZnO powders were placed in a high-energy ball mill using 5mm diameter zirconia balls as the medium, with a strictly controlled ball-to-powder ratio of 10:1. Under nitrogen protection (purity ≥99.99%), the milling was carried out at 300 rpm for 4 hours to obtain nano-Cr2O3 and nano-ZnO powders with a particle size of ≤200 nm. During the nano-crushing process, a 10-minute pause was taken every 30 minutes to avoid local overheating and ensure the uniformity and stability of the nanoparticles.

[0038] S2. Surface modification: Disperse the nano-Cr2O3 powder and nano-ZnO powder in 60 ml of a 95% ethanol solution containing 1 wt.% of a silane coupling agent (KH-550). Ultrasonic treatment was performed for 30 minutes using an ultrasonic cleaner (200 W power, 40 kHz frequency) to ensure adequate dispersion and surface modification. The suspension was then dried in a vacuum drying oven at 60°C (vacuum ≤ 0.1 MPa) for 12 hours to obtain surface-modified nano-Cr2O3 and nano-ZnO powders.

[0039] S3, corrosion inhibitor composite and gradient dispersion, according to Table 1, respectively weighed surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO, selected c50 ordinary Portland cement as grouting material, made anchoring sample M2.

[0040] 0.2% polycarboxylate superplasticizer was added to anchor specimen M2, followed by deionized water, with a water-cement ratio strictly controlled at 0.32. The mixture was pretreated for 20 minutes using an ultrasonic disperser (frequency 40 kHz, power 500 W), followed by stirring for 1 hour using a high-speed mechanical stirrer (speed 2000 rpm) to form a uniform suspension. The dispersion of the suspension was monitored using a laser particle size analyzer to ensure uniform particle distribution and the absence of agglomerates.

[0041] S4. Grouting and curing: Inject the suspension into a standard 40mm×40mm×40mm steel mold and vibrate it for 2 minutes using a vibration table (frequency 50Hz, amplitude 0.5mm) to compact the slurry and remove any bubbles. After molding, place the standard specimen in a constant temperature and humidity curing room (temperature 20±1°C, relative humidity ≥95%) for 7 days. During the curing process, regularly check the humidity and temperature of the specimen daily to ensure a stable curing environment. After curing, dry the specimen in a vacuum drying oven (vacuum degree ≤0.1MPa) for 24 hours to produce anchor specimen G2. The specimen undergoes a compressive strength test using a compressive strength tester to ensure that its mechanical properties meet the requirements.

[0042] S5. Crushing and Immersion: Crushing the 7-day-old anchor specimen G2. 300 g of crushed sample with a particle size ≤5 mm was placed in a sealed extraction container. 500 ml of deionized water was added at a solid-to-liquid ratio of 1:1.67. The sample was shaken and immersed for 48 hours at a constant temperature of 25°C (frequency 2 Hz). Simulated pore fluid was filtered through a 0.45 μm filter membrane to obtain the obtained solution. The pretreated anchor specimen was immersed in the extract for 48 hours to establish the contact interface with the corrosive medium. Anchor specimen G2 was then prepared and transferred to an argon atmosphere for storage for subsequent Tafel polarization curve and electrochemical impedance spectroscopy testing.

[0043] Example 4 A method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables (preparation of anchor sample G3) comprises the following steps: S1. Nano-crushing: Cr2O3 and ZnO powders were placed in a high-energy ball mill using 5mm diameter zirconia balls as the medium, with a strictly controlled ball-to-powder ratio of 10:1. Under nitrogen protection (purity ≥99.99%), the milling was carried out at 300 rpm for 4 hours to obtain nano-Cr2O3 and nano-ZnO powders with a particle size of ≤200 nm. During the nano-crushing process, a 10-minute pause was taken every 30 minutes to avoid local overheating and ensure the uniformity and stability of the nanoparticles.

[0044] S2. Surface modification: Disperse the nano-Cr2O3 powder and nano-ZnO powder in 60 ml of a 1 wt.% ethanol solution (95%) containing a silane coupling agent (KH-550). Ultrasonic treatment was performed for 30 minutes using an ultrasonic cleaner (200 W power, 40 kHz frequency) to ensure adequate dispersion and surface modification. The suspension was then dried in a vacuum drying oven at 60°C (vacuum degree ≤ 0.1 MPa) for 12 hours to obtain surface-modified nano-Cr2O3 and nano-ZnO powders.

[0045] S3, corrosion inhibitor composite and gradient dispersion, according to Table 1, respectively weighed surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO, selected c50 ordinary Portland cement as grouting material, made anchoring sample M3.

[0046] 0.2% polycarboxylate superplasticizer was added to anchor specimen M3, followed by deionized water, with a water-cement ratio strictly controlled at 0.32. The mixture was pretreated for 20 minutes using an ultrasonic disperser (frequency 40 kHz, power 500 W), followed by stirring for 1 hour using a high-speed mechanical stirrer (speed 2000 rpm) to form a uniform suspension. The dispersion of the suspension was monitored using a laser particle size analyzer to ensure uniform particle distribution and the absence of agglomerates.

[0047] S4. Grouting and curing: Inject the suspension into a standard 40mm×40mm×40mm steel mold and vibrate for 2 minutes using a vibration table (frequency 50Hz, amplitude 0.5mm) to compact the slurry and remove any bubbles. After molding, place the standard specimen in a constant temperature and humidity curing chamber (temperature 20±1°C, relative humidity ≥95%) for 7 days. During the curing process, regularly check the humidity and temperature of the specimen daily to ensure a stable curing environment. After curing, dry the specimen in a vacuum drying oven (vacuum degree ≤0.1MPa) for 24 hours to produce anchor specimen G3. The specimen undergoes a compressive strength test using a compressive strength tester to ensure that its mechanical properties meet the requirements.

[0048] S5. Crushing and Immersion: Crushing the 7-day-old anchor specimen G3. 300 g of the crushed sample with a particle size ≤5 mm was placed in a sealed extraction container. 500 ml of deionized water was added at a solid-to-liquid ratio of 1:1.67. The sample was shaken and immersed for 48 hours (2 Hz frequency) at a constant temperature of 25°C. The simulated pore fluid was filtered through a 0.45 μm filter membrane to obtain the simulated pore fluid. The pretreated anchor specimen was immersed in the extraction solution for 48 hours to establish the contact interface with the corrosive medium. Anchor specimen G3 was prepared and transferred to an argon atmosphere for storage for subsequent Tafel polarization curve and electrochemical impedance spectroscopy testing.

[0049] Example 5 The preparation of the anchor specimen CG and the anchor cable specimen CG includes the following steps: S1. Grouting and Curing: C50 ordinary Portland cement was used as the grouting material. The grouting material was injected into a standard 40 mm × 40 mm × 40 mm steel mold. The grouting was compacted using a vibration table (frequency 50 Hz, amplitude 0.5 mm) for 2 minutes to remove any bubbles from the slurry. After molding, the standard specimens were placed in a constant temperature and humidity curing chamber (temperature 20 ± 1°C, relative humidity ≥ 95%) for 7 days. During the curing process, the humidity and temperature of the specimens were checked regularly daily to ensure a stable curing environment. After curing, the specimens were dried in a vacuum drying oven (vacuum ≤ 0.1 MPa) for 24 hours to produce anchor specimens CG. The specimens were subjected to compressive strength testing using a compressive strength tester to ensure that their mechanical properties met the requirements.

[0050] S2, impregnation, collects in-situ leachate from deep mines, and prepares anchor cable specimens CG after 48 h of dynamic impregnation of pretreated anchor cable specimens. The specimens are then transferred to an argon protected environment for storage for subsequent Tafel polarization curve and electrochemical impedance spectroscopy tests.

[0051] Characterization and analysis: (1) Strength test The compressive strength tests were carried out on anchor specimens G1, G2, G3 and the control group anchor specimen CG. The results are shown in the figure. Figure 2 As shown. Figure 2 It can be seen that after 1 day of curing, the compressive strength of anchor specimens G2 and G3 was lower than that of the control anchor specimen CG. However, after 7 days of curing, the compressive strength of anchor specimen G1 was slightly higher than that of the control anchor specimen CG. This indicates that the corrosion inhibitor has no adverse effect on anchor solidification and strength after 7 days of normal curing. Moreover, the strength of anchor specimen G1 was slightly higher than that of the control anchor specimen CG, which is consistent with the high-strength characteristics of anchor cable support in deep coal mines and is a suitable corrosion inhibitor.

[0052] (2) Potentiodynamic polarization curve test The potentiodynamic polarization curve test was conducted on the anchor cable specimen G1 of Example 2, the anchor cable specimen G2 of Example 3, the anchor cable specimen G3 of Example 4 and the anchor cable specimen CG of the control group of Example 5. The results are as follows: Figure 3 shown.

[0053] Depend on Figure 3 It can be seen that the corrosion inhibition performance evaluation based on the polarization curve test shows that the composite corrosion inhibitor has a significant regulatory effect on the electrochemical behavior of the anchor specimens. The electrochemical test data show that the anchor specimens G1-G3 modified with the corrosion inhibitor show a significant positive shift in corrosion potential compared with the blank group, and the average anodic polarization amplitude reaches 0.16V, indicating that the thermodynamic corrosion tendency of the material surface is effectively controlled. Further kinetic parameter analysis shows that the corrosion current density of the corrosion inhibitor-treated group shows an order of magnitude downward trend, among which the anchor specimen G1 shows the best corrosion inhibition performance, and its current density value increases from the initial 2.29×10-4 A / cm 2 Significantly reduced to 8.52×10 -6 A / cm 2 The corrosion rate attenuation coefficient reaches 96.3%. This numerical comparison result fully verifies the key role of the composite corrosion inhibitor in the metal passivation process, and its corrosion inhibition efficiency is significantly better than that of the conventional single corrosion inhibition system.

[0054] (3) Electrochemical impedance spectroscopy test Electrochemical impedance spectroscopy (EIS) is a key technology for studying electrochemical systems. It measures the system's response to AC signal disturbances of varying frequencies to obtain impedance information. A three-electrode system is often used in this test. A small AC voltage is superimposed on a DC potential and applied between the working electrode and the reference electrode. The AC current of the working electrode is measured, and the frequency is varied to record the data to obtain the electrochemical impedance spectrum. The data is presented as Nyquist and Bode plots, and equivalent circuit fitting is used to obtain circuit element parameters such as resistance and capacitance. These parameters can reflect the physical and chemical processes of the system. EIS is widely used in research fields such as batteries, corrosion, electrocatalysis, and sensors, providing key information for related research.

[0055] A CS310 electrochemical workstation manufactured by Wuhan Koster was used. A saturated calomel electrode and platinum wire were used as the reference electrode and auxiliary electrode, respectively. To ensure the applicability of the invention, the conductive solution was water sprayed from the roof of a coal mine. Testing was performed at a frequency interval of 0.01-100,000 Hz and an amplitude of ±3 mV at the self-corrosion potential.

[0056] An equivalent circuit is fitted for the sample, where Rs is the solution resistance, Rf is the double-layer capacitance, CPEf is the protective film capacitance, and Rct is the charge transfer resistance. Figure 4 The middle curve is the Nyquist plot of electrochemical impedance spectroscopy, Figure 4 It can be seen that the impedance radius of the anchor cable specimens G1, G2, and G3 is significantly larger than that of the anchor cable specimen CG in the control group. Since the increase in impedance radius indicates an improvement in corrosion resistance, it is proved that the anchor cable specimens G1, G2, and G3 have better corrosion resistance and the corrosion inhibitor plays a better role.

[0057] The corrosion inhibitor Cr2O3+Na3PO4+ZnO significantly reduces the corrosion rate of the anchor material through a synergistic effect of multiple mechanisms. Its corrosion inhibition mechanism can be systematically analyzed from the aspects of passive film formation, adsorption film formation, cathodic inhibition and synergistic effect. First, the passive film formation and self-repair mechanism of Cr2O3 enable nano-Cr2O3 to react with Fe on the anchor surface in an alkaline grouting environment (pH ≈ 12) to form a dense Cr(OH)3 or Cr2O3·nH2O passive film, which effectively blocks Cl - 、SO4 2-The silane coupling agent modification enhances the interface bonding between Cr2O3 and the grouting matrix, avoids particle agglomeration, and ensures uniform coverage of the passivation film. Therefore, when there is local damage, Cr 3+ The passivation layer is rapidly regenerated through redox reactions to maintain the integrity of the film.

[0058] In addition, the dual effects of adsorption and precipitation of Na3PO4 cause Na3PO4 to hydrolyze and generate PO4 3- ions, and Fe 2+ Combined to form insoluble FePO4 precipitation, covering the anode active sites and blocking the anode reaction. 3- By chemically adsorbing on the metal surface to form a monolayer (Langmuir model), it inhibits the oxygen reduction reaction (cathodic process) and reduces the corrosion current density. Na3PO4 acts as a dispersion carrier, promoting the uniform distribution of Cr2O3 and ZnO, and optimizing the interface microenvironment.

[0059] Cathodic protection and physical barrier effect of ZnO Nano-ZnO dissolution releases Zn 2+ , in the cathode region with OH - The reaction forms a Zn(OH)2 precipitate film, which inhibits oxygen diffusion and cathode reduction reactions. ZnO particles fill the pores of the grouting material, reducing the permeability of the medium and forming a physical barrier to slow the spread of corrosive media. The modified ZnO and Cr2O3 form a "film-film interlocking" structure through hydrogen bonding, improving overall density.

[0060] The synergistic mechanism of these three elements involves spatial complementarity: Cr2O3 covers the anodic region, ZnO suppresses the cathodic region, and Na3PO4 fills interfacial defects, forming a comprehensive surface protection network. It also involves electrochemical coupling: the passivation potential of Cr2O3 (+0.16V) and the cathodic polarization effect of ZnO synergistically reduce the corrosion driving force. This synergistic effect also strengthens the structure, dispersing the nanoparticles within the grouting matrix, increasing material density and reducing the penetration path of the corrosive medium.

[0061] The synergistic effect of Cr2O3, Na3PO4 and ZnO in this patent is the key to significantly improving its corrosion inhibition effect. The three work together to form a multiple protection mechanism: Cr2O3 protects the anode area through the passivation film, Na3PO4 protects the entire surface through the adsorption film and precipitation film, and ZnO reduces the corrosion current by inhibiting the cathode reaction. This synergistic effect can not only optimize the microenvironment of the metal surface, but also reduce Cl - The concentration of corrosive ions such as chlorinated ions can also optimize the internal structure of the material to a certain extent, improving the strength and durability of the anchor material. The corrosion inhibitor has good compatibility with the grouting material and will not affect the solidification process of the material. At the same time, it can also improve the overall performance of the material through structural optimization.

[0062] In summary, the corrosion inhibitor Cr2O3+Na3PO4+ZnO significantly reduces the corrosion rate of anchor materials through multiple mechanisms, including passive film formation, adsorption film formation, cathodic inhibition, and synergistic corrosion inhibition. Its excellent corrosion inhibition performance and good compatibility give it broad application prospects in deep coal mine environments. Through in-depth research and optimization, this corrosion inhibitor is expected to become an important solution for corrosion protection of anchor grouting materials in deep coal mines. Comprehensive evaluation shows that anchor specimen G1 has the best corrosion resistance. Therefore, the corrosion inhibitor ratio of Cr2O3+Na3PO4(A+B) 0.5%+0.1% (1kg grouting material + 5g reagent A + 1g reagent B) is the best choice.

[0063] The present invention demonstrates significant technical benefits. By nano-sizing and surface-modifying the corrosion inhibitor raw materials, and optimizing the compounding and dispersion processes, it effectively improves the uniformity and stability of the corrosion inhibitor in the grouting material, ensuring its full effectiveness and enhancing the protective performance of the anchor cable specimens. Furthermore, strict control of parameters in each preparation step ensures that the mechanical properties of the specimens meet requirements, providing a more reliable protection solution for deep coal mine support.

[0064] After the corrosion inhibitor was added to the present invention, the corrosion rate of the anchor cable specimen was significantly reduced, which was specifically manifested in an increase in the impedance radius, a decrease in the corrosion current density, and an improvement in the surface morphology. Electrochemical impedance spectroscopy tests showed that the impedance radius of the sample with the addition of the corrosion inhibitor was significantly increased, indicating that its corrosion resistance was significantly improved. Polarization curve tests showed that the corrosion current density of the sample with the addition of the corrosion inhibitor was significantly reduced, indicating that the corrosion inhibitor effectively suppressed the progress of the corrosion reaction. Scanning electron microscopy observations showed that the corrosion products on the surface of the sample with the addition of the corrosion inhibitor were significantly reduced, and the surface morphology was more uniform and dense. These experimental results fully verified the effectiveness of the corrosion inhibitor.

[0065] From a prospective perspective, this corrosion inhibitor offers advantages such as simple preparation, low cost, and good compatibility. It is suitable for corrosion protection of anchoring materials used in cable grouting in deep coal mines. Its multiple protective mechanisms and synergistic corrosion inhibition can significantly extend the service life of anchoring materials, ensuring the safety and stability of deep coal mining. Future research will further optimize the inhibitor's formulation and addition ratio to enhance its effectiveness and cost-effectiveness.

[0066] In the present invention, the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0067] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A composite corrosion inhibitor for grouting of deep coal mine support anchor cables, characterized in that: The composite corrosion inhibitor consists of surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO.

2. The grouting composite corrosion inhibitor for deep coal mine support anchor according to claim 1, characterized in that: The mass ratio of the surface-modified nano-Cr2O3, Na3PO4 and the surface-modified nano-ZnO is 5:1-10:1-10.

3. A method for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables according to claim 1, characterized in that: The following steps are involved: S1, nano-processing, ball milling Cr2O3 and ZnO powders under inert gas protection to obtain nano-Cr2O3 and nano-ZnO; S2, surface modification treatment, respectively dispersing nano-Cr2O3 and nano-ZnO in an organic solution containing a silane coupling agent, ultrasonically treating and then drying to obtain surface-modified nano-Cr2O3 and surface-modified nano-ZnO; S3. Preparation of composite corrosion inhibitor: mixing surface-modified nano-Cr2O3 and surface-modified nano-ZnO with Na3PO4 to prepare composite corrosion inhibitor.

4. The method for preparing the grouting composite corrosion inhibitor for deep coal mine support anchor according to claim 3, characterized in that: In step S1, Cr2O3 and ZnO powders are placed in a ball mill respectively, using zirconia balls as the medium and a ball-to-material ratio of 10:1, and ball milling is carried out at a speed of 300 rpm for 4 hours under inert gas protection to obtain nano-Cr2O3 and nano-ZnO with a particle size of ≤200 nm.

5. The method for preparing the grouting composite corrosion inhibitor for deep coal mine support anchor according to claim 3, characterized in that: In step S2, nano-Cr2O3 and nano-ZnO are dispersed in an ethanol solution containing 1 wt.% of a silane coupling agent, ultrasonically treated for 30 minutes, and then dried at 60°C to obtain surface-modified nano-Cr2O3 and surface-modified nano-ZnO.

6. The use of the composite corrosion inhibitor for grouting of deep coal mine support anchor cables according to any one of claims 3 to 5, characterized in that: The composite corrosion inhibitor is used in the fields of deep coal mine tunnel support, tunnel engineering, underground engineering or marine engineering.

7. The use of the composite corrosion inhibitor for grouting of deep coal mine support anchor cables according to claim 6, characterized in that: The composite corrosion inhibitor is used as an anchor grouting material for deep coal mine tunnels.

8. The method for using the grouting composite corrosion inhibitor for deep coal mine support anchor cables according to any one of claims 3 to 5, characterized in that: The following steps are involved: (1) Surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO were uniformly added to the grouting material, and c50 ordinary Portland cement was selected as the grouting material to prepare the anchoring specimen M; (2) Add 0.2% polycarboxylate water reducer to the anchoring specimen M, inject deionized water with a water-cement ratio of 0.32, use an ultrasonic disperser for pretreatment, and then mechanically stir at a speed of 2000 rpm to form a uniform suspension; (3) The suspension is injected into a mold and compacted by vibration to form a standard specimen of 40 mm × 40 mm × 40 mm. The standard specimen is cured in a constant temperature and humidity curing room and then vacuum dried to obtain the anchor specimen G.

9. The method for using the grouting composite corrosion inhibitor for deep coal mine support anchor according to claim 8, characterized in that: In step (2), the frequency of the ultrasonic disperser is 40 kHz and the power is 500 W; in step (3), the temperature of the constant temperature and humidity curing room is 20±1°C and the relative humidity is ≥95%.

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