A method and apparatus for quality control of high-mica granite manufactured sand and gravel concrete

Abstract

This invention relates to a method and apparatus for quality control of high-mica granite manufactured sand and gravel concrete, comprising the following steps: S1, conveying pretreated granite aggregate to a dual-cavity microwave irradiation device; S2, the dual-cavity microwave irradiation device detects the dielectric constant of the granite aggregate, and performs high-frequency treatment on granite aggregate with a dielectric loss factor greater than 0.05, and low-frequency treatment on granite aggregate with a dielectric loss factor less than or equal to 0.05; S3, conveying the microwave-treated granite aggregate to a liquid nitrogen spraying device, and inducing microcracks between mica layers through thermal shock stress, thereby triggering interlayer delamination of mica; S4, restoring the granite aggregate to room temperature through a reheating device, and separating the granite aggregate from the mica on it through an air separation and impurity removal device. This invention employs microwave-liquid nitrogen synergistic delamination technology to reduce the mica content in high-mica granite, thereby achieving quality control of granite manufactured sand and gravel concrete.

Description

Technical Field

[0001] This invention relates to the field of concrete production technology, and in particular to a method and apparatus for quality control of high-mica granite manufactured sand and gravel concrete. Background Technology

[0002] The performance of concrete is highly dependent on the quality of aggregates. Granite, due to its high hardness and weather resistance, is one of the ideal aggregate sources. However, some granites (such as two-mica granite and biotite granite) have a mica content as high as 5%-10%, leading to the following problems in concrete: Reduced strength: The smooth cleavage surface of mica results in weak bonding with cement paste, leading to a 20%-30% decrease in 28-day compressive strength. Deteriorated durability: Mica expands after absorbing water, inducing microcracks and increasing the chloride ion diffusion coefficient by 1-2 orders of magnitude. Fluctuations in workability: Flaky mica hinders particle flow, increasing the slump loss rate by more than 40%. Currently, approximately 300 million tons of natural granite aggregate from tunnel excavation worldwide are discarded annually due to excessive mica content.

[0003] Mica is an aluminosilicate mineral with a continuous layered silica tetrahedral structure. As a harmful impurity in manufactured granite sand, its content significantly affects the workability, mechanical properties, and durability of concrete. The interface is the weakest point in concrete and plays a crucial role in the failure process. The failure process is closely related to the properties of the aggregates and the strength differences between the matrix. The type, strength, shape, surface impurities, porous structure, water absorption, and surface bond strength of the aggregates have a significant impact on concrete, especially high-performance concrete.

[0004] Existing technologies for processing mica in granite mainly include mechanical sorting and acid washing. Mechanical sorting utilizes the density difference between mica and quartz / feldspar (mica 2.7-3.1 g / cm³, quartz 2.65 g / cm³), separating particles through airflow or heavy liquid. However, it easily leads to the loss of fine particles, with a sorting efficiency of only 50%-60% for particles <0.6 mm, resulting in a shortage of fine aggregate. Acid washing uses hydrofluoric acid (HF) to dissolve the Al₂O₃ between the mica layers. 3+ This can easily lead to surface corrosion of aggregates, increase porosity by more than 15%, increase crushing value by 3-5 percentage points, and still result in 3-4% residual mica after mechanical sorting. In addition, each ton of aggregate produces 50-80L of fluoride-containing wastewater, resulting in high treatment costs.

[0005] To address the shortcomings of existing technologies, this invention provides a quality control system for high-mica granite manufactured sand and gravel concrete. It employs microwave-liquid nitrogen synergistic stripping technology to reduce the mica content in high-mica granite, thereby achieving quality control of the granite manufactured sand and gravel concrete. The system generates no acid washing wastewater, the liquid nitrogen is recyclable (recovery rate > 85%), exhibits high selectivity, a mica stripping rate > 80%, and a quartz / feldspar damage rate < 3%. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method and apparatus for quality control of high mica granite manufactured sand and gravel concrete, which adopts microwave-liquid nitrogen synergistic stripping technology to reduce the mica content in high mica granite, so as to achieve quality control of granite manufactured sand and gravel concrete.

[0007] The specific technical solution is as follows:

[0008] A method for quality control of high-mica granite manufactured sand and gravel concrete includes the following steps:

[0009] S1, the pre-treated granite aggregate is transported to a dual-cavity microwave irradiation device. By utilizing the sensitivity of water molecules between mica layers to microwaves, microwave radiation induces the expansion of mica crystal layers, thereby weakening the interlayer bonding force.

[0010] S2, a dual-cavity microwave irradiation device is used to detect the dielectric constant of granite aggregates. Granite aggregates with a dielectric loss factor greater than 0.05 are subjected to high-frequency processing, while granite aggregates with a dielectric loss factor less than or equal to 0.05 are subjected to low-frequency processing.

[0011] S3, microwave-treated granite aggregate is transported to liquid nitrogen spraying equipment, liquid nitrogen is sprayed on the surface of granite aggregate, and micro-cracks are generated between mica layers through thermal shock stress, which triggers the peeling of mica layers.

[0012] S4, the granite aggregate is restored to room temperature by a reheating device, and the granite aggregate is separated from the mica on it by an air classifier.

[0013] Furthermore, it also includes the following steps:

[0014] S5 involves immersing the air-classified granite aggregate in a mixture of silane coupling agent and nano-SiO2 sol, drying it at 120°C to form a composite layer with a thickness of 250-350nm, thereby reducing the porosity of the mica-cement interface transition zone.

[0015] S6 uses the MgO-KH2PO4 system to pre-coat granite aggregate, generating struvite phase to close the cleavage surfaces of mica, which is then used in the preparation of concrete.

[0016] Further, in step S1, the pretreatment of the granite aggregate includes the following steps:

[0017] S11, crush the granite aggregate and separate the crushed granite aggregate into two grades, 5-10mm and 10-20mm, by using a vibrating screen;

[0018] S12, the granite aggregate is graded and conveyed to the vibrating feeder, which then uniformly conveys the granite aggregate to the pulse airflow cleaning equipment to remove dust from the surface of the granite aggregate.

[0019] Further, in step S2, the dielectric constant detection of the granite aggregate includes the following steps:

[0020] S21, intermittently detects granite aggregates transported to a dual-cavity microwave irradiation device using several dielectric constant sensors;

[0021] S22, obtain the dielectric loss factor detected by several dielectric constant sensors each time, and calculate the average value of several dielectric loss factors as the ideal value for this detection;

[0022] S23. Based on the ideal values, the granite aggregate tested in this study will undergo appropriate high-frequency or low-frequency treatment.

[0023] Furthermore, in step S2, the high-frequency processing frequency is 2450MHz, the power density is 3.5kW / t, and the duration is 50-60 seconds.

[0024] Furthermore, in step S2, the low-frequency processing frequency is 915MHz, the power density is 1.8kW / t, and the duration is 80-90 seconds.

[0025] Further, in step S3, spraying liquid nitrogen includes the following steps:

[0026] S31, the microwave-treated granite aggregate is alternately stored in a dual-station buffer bin. When one buffer bin is in the collection state, the other is in the feeding state to the liquid nitrogen spraying equipment. The internal temperature of the buffer bin needs to be detected before each feeding.

[0027] S32, after temperature detection, the aggregate flows into the liquid nitrogen spraying equipment, and several nozzles are individually controlled to spray liquid nitrogen onto the granite aggregate;

[0028] S33: The number of nozzles to be turned on is determined by the temperature before feeding the buffer bin. The higher the temperature, the more nozzles to be turned on.

[0029] Further, in step S5, the formation of the composite layer includes the following steps:

[0030] S51, tetraethyl orthosilicate, ethanol, and water are mixed in a molar ratio of 1:8:2, and 3-3.5 wt% of silane coupling agent is added. The pH is adjusted to 9.0-9.8 using ammonia as a catalyst, and hydrolysis is carried out for 4 hours.

[0031] S52, soak the air-classified granite aggregate for 30 minutes, centrifuge to dehydrate for 30 seconds, and then heat-cure at 120℃ for 1 hour;

[0032] S53, the film thickness was measured by an ellipsometry and controlled within 300±50nm.

[0033] Further, in step S6, the pre-wrapping includes the following steps:

[0034] S61, set the MgO and KH2PO4 molar ratio to 3:1, the water-cement ratio to 0.10, and the borax retarder addition to 1.5%, and use a twin-shaft forced mixer to coat the granite aggregate with the first layer;

[0035] S62, with a MgO to KH2PO4 molar ratio of 5:1, a water-cement ratio of 0.15, and a borax retarder addition of 2.5%, uses a twin-shaft forced mixer to coat the granite aggregate with a second layer.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention provides a method and apparatus for quality control of high mica granite manufactured sand and gravel concrete. It utilizes the sensitivity of water molecules between mica layers to microwaves, induces the expansion of mica crystal layers through microwave radiation, weakens the interlayer bonding force, and then sprays liquid nitrogen onto the surface of granite aggregate. Through thermal shock stress, microcracks are generated between mica layers, which triggers the delamination of mica layers. The microwave-liquid nitrogen synergistic delamination technology is used to reduce the mica content in high mica granite, so as to achieve quality control of granite manufactured sand and gravel concrete.

[0038] (2) The present invention provides a method and apparatus for quality control of high mica granite manufactured sand and gravel concrete. By detecting the dielectric constant of high mica granite aggregate before microwave irradiation, granite aggregate with dielectric loss factor greater than 0.05 is subjected to high frequency processing, and granite aggregate with dielectric loss factor less than or equal to 0.05 is subjected to low frequency processing. Thus, different irradiation methods are used to irradiate the mica on the granite aggregate, which facilitates the peeling of mica.

[0039] (3) The present invention provides a method and apparatus for quality control of high mica granite manufactured sand and gravel concrete. The granite aggregate after microwave-liquid nitrogen synergistic stripping is immersed in a mixture of silane coupling agent and nano SiO2 sol, and the granite aggregate is pre-coated with MgO-KH2PO4 system to further enhance the bonding force with cement.

[0040] (4) The present invention provides a method and apparatus for quality control of high mica granite manufactured sand and gravel concrete. By setting up a dual-cavity microwave irradiation device, a dielectric constant detection component is used to detect the dielectric loss factor of the aggregate in each detection area, and the aggregate is distributed to the corresponding high-frequency irradiation cavity or low-frequency irradiation cavity by a material distribution component, which facilitates the classification and processing of different aggregates and improves the stripping effect of mica.

[0041] (5) The present invention provides a method and apparatus for quality control of high mica granite manufactured sand and gravel concrete. By setting an alternating buffer component, the driving component can make the first station buffer bin and the second station buffer bin alternately move to the position directly below the second discharge port for alternating buffering of granite aggregate heated by microwave box. The upper ports of the first station buffer bin and the second station buffer bin are flush with the upper end surface of the alternating plate, and the upper end surface of the alternating plate is in contact with the lower port of the second discharge port. This setting can prevent microwaves in the microwave box from overflowing from the second discharge port, and facilitate temperature detection of the aggregate after microwave, and facilitate the subsequent control of liquid nitrogen spraying volume. Attached Figure Description

[0042] Figure 1 This is a flowchart of the method of the present invention.

[0043] Figure 2 This is a schematic diagram of the overall equipment location distribution of the present invention.

[0044] Figure 3 This is a schematic diagram of the dual-cavity microwave irradiation device of the present invention.

[0045] Figure 4 This is the present invention. Figure 3 A magnified view of part A.

[0046] Figure 5 This is a schematic diagram of the alternating buffer component structure of the present invention.

[0047] Figure 6 This is a schematic diagram of the drive component structure of the present invention.

[0048] Figure 7 This is a schematic diagram of the liquid nitrogen spraying device of the present invention.

[0049] Figure 8 This is a schematic diagram of the reheating device of the present invention.

[0050] In the diagram: 1. Vibrating feeder; 2. Pulse airflow cleaning equipment; 3. Dual-cavity microwave irradiation equipment; 31. Microwave box; 32. Dielectric constant detection component; 321. Dielectric constant detection chamber; 322. Second feed inlet; 323. Third discharge outlet; 324. Third conveyor belt; 325. Dielectric constant sensor; 33. Partition plate; 34. High-frequency irradiation cavity; 35. Low-frequency irradiation cavity; 36. Feed pipe; 37. Material distribution assembly; 371. Material distribution plate; 372. Material distribution shaft; 38. First feed inlet; 39. First discharge outlet; 310. Second discharge outlet; 311. First magnetron; 312. Second magnetron; 313. First conveyor belt; 314. Second conveyor belt; 4. Alternating buffer component; 41. Rectangular... Frame; 42. Alternating plate; 43. First station buffer bin; 44. Second station buffer bin; 45. First groove; 46. First guide support rod; 47. First telescopic cylinder; 48. Second telescopic cylinder; 49. Temperature sensor; 410. Hinge block; 5. Liquid nitrogen spraying equipment; 51. Spray box; 52. Spray chamber; 53. Fourth conveyor belt; 54. Third feed inlet; 55. Fourth feed inlet; 56. Spray main pipe; 57. Nozzle; 58. Recovery pipe; 59. Fourth discharge port; 6. Reheating equipment; 61. Reheating box; 62. Fifth feed inlet; 63. Fifth conveyor belt; 64. Sixth conveyor belt; 65. Hot air box; 66. Heating rod; 67. Exhaust fan; 68. Fifth discharge port; 7. Air separation and impurity removal equipment. Detailed Implementation

[0051] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] Example 1

[0054] This invention provides a method and apparatus for quality control of high-mica granite manufactured sand and gravel concrete, with reference to... Figure 1 The process includes step S1, where the pre-treated granite aggregate is transported to a dual-cavity microwave irradiation device 3. Utilizing the sensitivity of mica interlayer water molecules to microwaves (dielectric loss tanδ = 0.03-0.05), microwave radiation induces expansion of the mica crystal layers, weakening the interlayer bonding force. Mica (KAl2(AlSi3O) 10The interlayer hydroxyl groups (-OH) and adsorbed water in mica exhibit high dielectric loss (tanδ≈0.04) to microwaves (2450MHz), while quartz / feldspar absorbs almost no microwaves. Targeted heating of the interlayer water in mica can locally raise the temperature to 110-150℃, while the temperature of the granite matrix is ​​<80℃. After microwave heating, the interlayer of mica expands, and the spraying of liquid nitrogen (-196℃) causes instantaneous contraction, generating shear stress.

[0055] The pretreatment of the granite aggregate includes the following steps:

[0056] S11, crush the granite aggregate and separate the crushed granite aggregate into two grades, 5-10mm and 10-20mm, by a vibrating screen (remove fine powder and dry with hot air at 80℃ until the moisture content is <0.5% to avoid free water interfering with microwave heating).

[0057] S12, the granite aggregate is graded and conveyed to the vibrating feeder 1. The vibrating feeder 1 evenly conveys the granite aggregate to the pulse airflow cleaning equipment 2 to remove dust from the surface of the granite aggregate. Pulse airflow cleaning (pressure 0.6MPa, air consumption 3m³ / t) removes surface powder (<0.075mm particles).

[0058] In step S2, the dual-cavity microwave irradiation device 3 detects the dielectric constant of the granite aggregate, and performs high-frequency processing on granite aggregate with a dielectric loss factor greater than 0.05, and low-frequency processing on granite aggregate with a dielectric loss factor less than or equal to 0.05.

[0059] In step S2, the dielectric constant detection of the granite aggregate includes the following steps:

[0060] S21, the granite aggregate delivered to the dual-cavity microwave irradiation device 3 is intermittently detected by several dielectric constant sensors 325;

[0061] S22, obtain the dielectric loss factor detected by several dielectric constant sensors 325 each time, and calculate the average value of several dielectric loss factors as the ideal value for this detection.

[0062] S23. Based on the ideal values, the granite aggregate tested in this study will undergo appropriate high-frequency or low-frequency treatment.

[0063] Several dielectric constant sensors 325 are arranged sequentially along the conveying direction of the granite aggregate. The dielectric constant sensors 325 operate synchronously and perform intermittent detection. The area between the two farthest dielectric constant sensors 325 is the detection area, and the time it takes for the granite aggregate to pass through this detection area is the intermittent wake-up time of each dielectric constant sensor 325. That is, each time, the dielectric constant sensor 325 performs concentrated detection on a number of aggregates flowing through the detection area. After detection, the aggregates flow into the dual-cavity microwave irradiation equipment 3, and subsequent aggregates to be detected flow through the detection area via the third conveyor belt 324 for detection, thus creating a cycle.

[0064] The high-frequency processing was performed at 2450MHz, with a power density of 3.5kW / t, for 50-60 seconds. This raised the surface temperature of the granite aggregate to 110±5℃ (controlled by infrared thermometry feedback). This process was applied to the interlayer water molecules in mica (structural formula KAl2(AlSi3O)). 10 (OH)2) Dielectric heating caused the interlayer spacing to expand from 1.0 nm to 1.8 nm (XRD detection).

[0065] The low-frequency processing operates at 915MHz with a power density of 1.8kW / t for 80-90 seconds. This process deeply heats the granite aggregate to 80-90℃, increasing the penetration depth by three times.

[0066] The transmission system uses a high-temperature resistant alumina ceramic conveyor belt for continuous aggregate conveying. It is resistant to temperatures of -200~300℃ and the speed is adjustable from 0.2 to 2m / min.

[0067] In step S3, the microwave-treated granite aggregate is transported to liquid nitrogen spraying equipment 5. Liquid nitrogen is sprayed onto the surface of the granite aggregate, and thermal shock stress induces micro-cracks between the mica layers, triggering interlayer delamination. The liquid nitrogen is stored in a Dewar flask (5000L volume, 1.2MPa operating pressure). The granite aggregate is cooled from 110℃ to -196℃, resulting in micro-cracks (5-20μm wide) between the mica flakes, achieving a delamination efficiency of 82-87%. After spraying, the liquid nitrogen becomes gaseous, and volatile organic compounds are collected in a condensation recovery tower. The residual gas is treated by catalytic oxidation.

[0068] Spraying liquid nitrogen includes the following steps:

[0069] S31, the microwave-treated granite aggregate is alternately stored in a dual-station buffer bin. When one buffer bin is in the collection state, the other is in the feeding state to the liquid nitrogen spraying device 5. The internal temperature of the buffer bin needs to be detected before each feeding.

[0070] S32, after temperature detection, the aggregate flows into the liquid nitrogen spraying equipment 5, and several nozzles 57 are individually controlled to spray liquid nitrogen onto the granite aggregate;

[0071] S33, according to the temperature before feeding the buffer bin, open the corresponding number of nozzles 57. The higher the temperature, the more nozzles 57 are opened.

[0072] Several nozzles 57 in the liquid nitrogen spraying equipment 5 are arranged sequentially along the conveying direction of the granite aggregate, and each nozzle 57 is controlled individually; the nozzles 57 spray liquid nitrogen (-196℃) at a flow rate ≥2L / min•t for 20 seconds, and the thermal shock stress causes microcracks >5μm to be generated between the mica layers.

[0073] S33: Based on the temperature before feeding the buffer bin, activate the corresponding number of nozzles 57. Higher temperatures result in more nozzles 57 being activated. Nozzles 57 are fan-shaped vacuum insulated nozzles with a spray angle of 60° and a spray distance of 150mm.

[0074] In step S4, the granite aggregate is restored to room temperature using the reheating device 6, and then separated from the mica on the granite aggregate using the air separation and impurity removal device 7. Hot air at 40℃ is used to reheat to room temperature (25℃) to avoid condensation adsorption. Utilizing the density difference between mica flakes (2.7-3.1 g / cm³) and granite particles (2.6-2.8 g / cm³), multi-stage airflow separation (wind speed 8-12 m / s, inclination angle 25°) is used to separate the flat particles (mica-rich portions) in the 5-20mm aggregate, reducing the mica content to below 2%.

[0075] Example 2

[0076] The interface transition zone between high-mica granite aggregate and cement matrix has three major defects: physical defects (mica cleavage surfaces are smooth (contact angle > 100°), resulting in weak mechanical interlocking force); chemical inertness (mica (KAl2(AlSi3O)...). 10 (OH)2) has a low surface hydroxyl density (only 1.2-1.5 hydroxyl groups / nm²), making it difficult to bond with cement hydration products; pores are concentrated: the porosity of the interfacial transition zone is 3-5 times higher than that of the cement matrix.

[0077] This invention provides a method and apparatus for quality control of high-mica granite manufactured sand and gravel concrete. Based on Example 1, it further includes step S5, in which the air-classified granite aggregate is immersed in a mixture of silane coupling agent and nano-SiO2 sol (particle size 20nm, solid content 15%), and dried at 120℃ to form a composite layer with a thickness of 250-350nm, reducing the porosity of the mica-cement interface transition zone by more than 40%. The nano-SiO2 network penetrates into the mica interlayer (depth 2-5μm), providing physical anchoring points. The nano-SiO2 sol utilizes an ethanol recovery system.

[0078] The formation of the composite layer includes the following steps:

[0079] S51, tetraethyl orthosilicate, ethanol, and water are mixed in a molar ratio of 1:8:2, and 3-3.5 wt% of silane coupling agent is added. The pH is adjusted to 9.0-9.8 using ammonia as a catalyst, and hydrolysis is carried out for 4 hours.

[0080] S52, soak the air-classified granite aggregate for 30 minutes, centrifuge to dehydrate (800 rpm, 30 s), and then heat-cure at 120℃ for 1 hour;

[0081] S53, the film thickness was measured by an ellipsometry and controlled within 300±50nm.

[0082] Film formation mechanism: Hydrolysis-condensation reaction generates ≡Si-O-Si≡ network, detected by infrared spectroscopy at 1080 cm⁻¹. -1 The intensity of the characteristic peak was increased by 2.3 times.

[0083] In step S52, the aggregate soaking step includes: preheating the aggregate to 60±5℃ (to reduce surface tension); immersing in sol (liquid-solid ratio 3:1), ultrasonic treatment for 15 min; centrifugation dehydration (800 rpm, 30 s, residual liquid rate <5%); and heat curing at 120℃ for 1 h to form a porous SiO2 gel film.

[0084] The process also includes step S6, which involves pre-coating the granite aggregate with an MgO-KH2PO4 system to create a struvite phase that closes the cleavage surfaces of the mica, which is then used in the preparation of concrete. The coating thickness is 150±20μm (controlled by an eddy current thickness gauge).

[0085] The pre-wrapping includes the following steps:

[0086] S61, with a MgO / KH2PO4 molar ratio of 3:1, a water-cement ratio of 0.10, a borax retarder addition of 1.5%, and can be mixed with 5% pore-forming agent (polystyrene microspheres, particle size 20-50μm). The granite aggregate is coated with the first layer using a twin-shaft forced mixer, and cured with steam at 80℃ for 2 hours during solidification to form a transition layer with a porosity of 35±3%.

[0087] S62, with a MgO / KH2PO4 molar ratio of 5:1, a water-cement ratio of 0.15, and a borax retarder addition of 2.5%, can be mixed with 1% nano-Al2O3 (to enhance wear resistance). A second layer of coating is applied to the granite aggregate using a twin-shaft forced mixer to fill the pores, achieving a surface hardness of HV450. After curing at room temperature for 24 hours, the surface hardness reaches HV450 (measured by microindentation method).

[0088] Example 3

[0089] Based on Embodiment 1, the dual-cavity microwave irradiation device 3 includes a microwave box 31. The upper end of the microwave box 31 is provided with a dielectric constant detection component 32 for conveying and detecting granite aggregate. The interior of the microwave box 31 is divided into a high-frequency irradiation cavity 34 and a low-frequency irradiation cavity 35 by a partition 33. A feed pipe 36 is also vertically arranged at one end of the interior of the microwave box 31. A material distribution component 37 for distributing granite aggregate to the high-frequency irradiation cavity 34 or the low-frequency irradiation cavity 35 is also provided at the lower end of the feed pipe 36.

[0090] The partition 33 is horizontally disposed inside the microwave box 31. The upper end of the partition 33 forms a high-frequency irradiation cavity 34 between itself and the inner wall of the microwave box 31. The lower end of the partition 33 forms a low-frequency irradiation cavity 35 between itself and the inner wall of the microwave box 31. The left end of the partition 33 is provided with a first feed port 38 that runs vertically through it. The right end of the partition 33 is provided with a first discharge port 39 that runs vertically through it. The right end of the lower surface of the microwave box 31 is provided with a second discharge port 310. The top of the high-frequency irradiation cavity 34 is provided with a plurality of first magnetrons 311. The bottom of the high-frequency irradiation cavity 34 is provided with a first conveyor belt 313. The top of the low-frequency irradiation cavity 35 is provided with a plurality of second magnetrons 312. The bottom of the low-frequency irradiation cavity 35 is provided with a second conveyor belt 314. The first magnetron 311 generates microwaves with a frequency of 2450MHz and a power density of 3.5kW / t. The first conveyor belt 313 moves granite aggregate with a dielectric loss factor greater than 0.05 from the high-frequency irradiation cavity 34 and heats it for 50-60 seconds, raising the surface temperature of the granite aggregate to 110±5℃. The aggregate is then discharged from the first outlet 39 and the second outlet 310. The second magnetron 312 generates microwaves with a frequency of 915MHz and a power density of 1.8kW / t. The second conveyor belt 314 moves granite aggregate with a dielectric loss factor less than or equal to 0.05 from the low-frequency irradiation cavity and heats it for 80-90 seconds, deeply heating the granite aggregate to 80-90℃. The aggregate is then discharged from the second outlet 310.

[0091] The dielectric constant detection component 32 includes a dielectric constant detection box 321 located at the upper end of the microwave box 31. The right end of the upper surface of the dielectric constant detection box 321 is provided with a second feed port 322 for communicating with the discharge end of the pulse dust removal equipment 2. The left end of the lower surface of the dielectric constant detection box 321 is provided with a third discharge port 323 for communicating with the upper port of the feed pipe 36. A third conveyor belt 324 for conveying granite aggregate is provided in the lower interior of the dielectric constant detection box 321 along the left-right direction. Several dielectric constant sensors 325 are provided in the upper interior of the dielectric constant detection box 321 along the left-right direction.

[0092] The material distribution assembly 37 includes a material distribution shaft 372. The front and rear ends of the material distribution shaft 372 are respectively connected to the front and rear sides of the microwave box 31 through bearings. A material distribution plate 371 that swings left and right is provided on the material distribution shaft 372 at the port of the feed pipe 36. A servo motor for driving the material distribution shaft 372 is provided on the rear end face of the microwave box 31. When the dielectric constant sensor 325 detects that the dielectric loss factor of the current granite aggregate is greater than 0.05, the servo motor controls the distribution plate 371 to swing to the left, and the upper end of the distribution plate 371 contacts the inner wall of the left side of the feed pipe 36, so that the granite aggregate in the feed pipe 36 flows to the high-frequency irradiation cavity 34; when the dielectric constant sensor 325 detects that the dielectric loss factor of the current granite aggregate is less than or equal to 0.05, the servo motor controls the distribution plate 371 to swing to the right, and the upper end of the distribution plate 371 contacts the inner wall of the right side of the feed pipe 36, so that the granite aggregate in the feed pipe 36 flows to the low-frequency irradiation cavity 35.

[0093] The alternating buffer component 4 includes a rectangular frame 41 located on the lower end face of the microwave oven 31. An alternating plate 42 is disposed inside the rectangular frame 41. A first-position buffer chamber 43 and a second-position buffer chamber 44 are symmetrically arranged at the left and right ends of the alternating plate 42. Temperature sensors 49 are respectively installed on the inner walls of the first-position buffer chamber 43 and the second-position buffer chamber 44. First grooves 45 are respectively provided on the front and rear inner walls of the rectangular frame 41. A driving component for moving the alternating plate 42 left and right is disposed inside the first groove 45. The first-position buffer chamber 43 and the second-position buffer chamber 44 alternately move to a position directly below the second discharge port 310 to alternately buffer the granite aggregate heated from the microwave oven 31. Discharge valves are respectively provided at the lower ends of the first-position buffer chamber 43 and the second-position buffer chamber 44. The upper ports of the first station buffer chamber 43 and the second station buffer chamber 44 are flush with the upper surface of the alternating plate 42, and the upper surface of the alternating plate 42 is in contact with the lower port of the second discharge port 310. This arrangement can prevent microwaves in the microwave box 31 from overflowing from the second discharge port 310.

[0094] The driving component includes a first guide support rod 46 arranged in a left-right direction. Several guide blocks adapted to the first guide support rod 46 are respectively provided on the front and rear end faces of the alternating plate 42. A hinge block 410 is respectively provided at the middle position of the front and rear end faces of the alternating plate 42. A first telescopic cylinder 47 and a second telescopic cylinder 48 are respectively provided on the left and right ends of the hinge block 410. The other end of the first telescopic cylinder 47 is hinged to the left inner wall of the first groove 45, and the other end of the second telescopic cylinder 48 is hinged to the right inner wall of the first groove 45. By extending the first telescopic cylinder 47 and retracting the second telescopic cylinder 48, the alternating plate 42 can be moved to the right, causing the first station buffer chamber 43 to move directly below the second discharge port 310. By retracting the first telescopic cylinder 47 and extending the second telescopic cylinder 48, the alternating plate 42 can be moved to the left, causing the second station buffer chamber 44 to move directly below the second discharge port 310.

[0095] The liquid nitrogen spraying equipment 5 includes a spray box 51, a spray chamber 52 at the right end of the spray box 51, a spray assembly inside the spray chamber 52, a fourth conveyor belt 53 arranged along the left-right direction inside the spray box 51, a third inlet 54 for receiving granite aggregate from the first station buffer bin 43 and a fourth inlet 55 for receiving granite aggregate from the second station buffer bin 44 at the left end of the upper surface of the spray box 51, and a fourth outlet 59 at the right end of the lower surface of the spray box 51. When the first station buffer bin 43 is in the aggregate receiving state, the second station buffer bin 44, after internal temperature detection, conveys aggregate into the spray box 51 through the fourth inlet 55; when the second station buffer bin 44 is in the aggregate receiving state, the first station buffer bin 43, after internal temperature detection, conveys aggregate into the spray box 51 through the third inlet 54.

[0096] The spray assembly includes a spray manifold 56, which is arranged along its length in the left-right direction. Several nozzles 57 are arranged along the length of the lower end of the spray manifold 56. The nozzles 57 are located above the fourth conveyor belt 53. A recovery pipe 58 for recovering waste gas is provided at the top of the spray chamber 52. The nozzles 57 are fan-shaped, and the spray range covers the width of the fourth conveyor belt 53. Each nozzle 57 is equipped with a solenoid valve. The corresponding number of nozzles 57 are activated according to the temperature of the aggregate being conveyed by the first or second station buffer bin 43, thereby cooling the aggregate at different temperatures and bringing the cooled aggregate to a more uniform temperature.

[0097] The reheating device 6 includes a reheating box 61. A fifth inlet 62, connected to a fourth outlet 59, is located at the right end of the upper surface of the reheating box 61. A fifth conveyor belt 63 and a sixth conveyor belt 64 for conveying aggregate are inclined inside the reheating box 61. A hot air box 65 is connected to the left end of the reheating box 61. A heating rod 66 and a fan 67 for conveying hot air into the reheating box 61 are located inside the hot air box 65. A fifth outlet 68 for conveying aggregate to the air-separated impurity removal device 7 is located at the lower surface of the reheating box 61. The granite aggregate, after being sprayed and cooled, falls through the fifth inlet 62 into the fifth conveyor belt 63, and after being conveyed by the fifth conveyor belt 63, falls into the sixth conveyor belt 64. After being conveyed by the sixth conveyor belt 64, it flows through the fifth outlet 68 to the air-separated impurity removal device 7. The fifth conveyor belt 63 and the sixth conveyor belt 64 can slow down the discharge time of the aggregate, allowing the aggregate to have sufficient time to reheat inside the reheating box 61.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for quality control of high-mica granite manufactured sand and gravel concrete, characterized in that, Includes the following steps: S1, the pre-treated granite aggregate is transported to a dual-cavity microwave irradiation device. By utilizing the sensitivity of water molecules between mica layers to microwaves, microwave radiation induces the expansion of mica crystal layers, thereby weakening the interlayer bonding force. S2, a dual-cavity microwave irradiation device is used to detect the dielectric constant of granite aggregates. Granite aggregates with a dielectric loss factor greater than 0.05 are subjected to high-frequency processing, while granite aggregates with a dielectric loss factor less than or equal to 0.05 are subjected to low-frequency processing. S3, microwave-treated granite aggregate is transported to liquid nitrogen spraying equipment, liquid nitrogen is sprayed on the surface of granite aggregate, and micro-cracks are generated between mica layers through thermal shock stress, which triggers the peeling of mica layers. S4, the granite aggregate is restored to room temperature by a reheating device and separated from the mica on it by an air classifier; S5 involves immersing the air-classified granite aggregate in a mixture of silane coupling agent and nano-SiO2 sol, drying it at 120°C to form a composite layer with a thickness of 250-350nm, thereby reducing the porosity of the mica-cement interface transition zone. S6 uses the MgO-KH2PO4 system to pre-coat granite aggregate, generating struvite phase to close the cleavage surfaces of mica, which is then used in the preparation of concrete.

2. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 1, characterized in that, In step S1, the pretreatment of the granite aggregate includes the following steps: S11, crush the granite aggregate and separate the crushed granite aggregate into two grades, 5-10mm and 10-20mm, by using a vibrating screen; S12, the granite aggregate is graded and conveyed to the vibrating feeder, which then uniformly conveys the granite aggregate to the pulse airflow cleaning equipment to remove dust from the surface of the granite aggregate.

3. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 1, characterized in that, In step S2, the dielectric constant detection of the granite aggregate includes the following steps: S21, intermittently detects granite aggregates transported to a dual-cavity microwave irradiation device using several dielectric constant sensors; S22, obtain the dielectric loss factor detected by several dielectric constant sensors each time, and calculate the average value of several dielectric loss factors as the ideal value for this detection; S23. Based on the ideal values, the granite aggregate tested in this study will undergo appropriate high-frequency or low-frequency treatment.

4. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 3, characterized in that, In step S2, the high-frequency processing frequency is 2450MHz, the power density is 3.5kW / t, and the duration is 50-60 seconds.

5. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 4, characterized in that, In step S2, the low-frequency processing frequency is 915MHz, the power density is 1.8kW / t, and the duration is 80-90 seconds.

6. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 1, characterized in that, In step S3, spraying liquid nitrogen includes the following steps: S31, the microwave-treated granite aggregate is alternately stored in a dual-station buffer bin. When one buffer bin is in the collection state, the other is in the feeding state to the liquid nitrogen spraying equipment. The internal temperature of the buffer bin needs to be detected before each feeding. S32, after temperature detection, the aggregate flows into the liquid nitrogen spraying equipment, and several nozzles are individually controlled to spray liquid nitrogen onto the granite aggregate; S33: The number of nozzles to be turned on is determined by the temperature before feeding the buffer bin. The higher the temperature, the more nozzles to be turned on.

7. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 1, characterized in that, In step S5, the formation of the composite layer includes the following steps: S51, tetraethyl orthosilicate, ethanol, and water are mixed in a molar ratio of 1:8:2, and 3-3.5 wt% of silane coupling agent is added. The pH is adjusted to 9.0-9.8 using ammonia as a catalyst, and hydrolysis is carried out for 4 hours. S52, soak the air-classified granite aggregate for 30 minutes, centrifuge to dehydrate for 30 seconds, and then heat-cure at 120℃ for 1 hour; S53, the film thickness was measured by an ellipsometry and controlled within 300±50nm.

8. The method for quality control of high-mica granite manufactured sand and gravel concrete according to claim 1, characterized in that, In step S6, the pre-wrapping includes the following steps: S61, set the MgO and KH2PO4 molar ratio to 3:1, the water-cement ratio to 0.10, and the borax retarder addition to 1.5%, and use a twin-shaft forced mixer to coat the granite aggregate with the first layer; S62, with a MgO to KH2PO4 molar ratio of 5:1, a water-cement ratio of 0.15, and a borax retarder addition of 2.5%, uses a twin-shaft forced mixer to coat the granite aggregate with a second layer.

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