A method for producing sand based on cobble processing machine sand

Abstract

The present application relates to a kind of method for making sand based on cob mechanism sand, it includes the process of screening to obtain cob masterbatch according to predetermined performance index, the process of being made by jaw crushing and conical crushing to make gravel, the process of using predetermined gradation gravel to make sand, and the process of scrubbing dehydration, the scrubbing dehydration process includes, along the water flow path of scrubbing sand washing sequentially configured water washing section, flocculation section and mixed washing section step;In flocculation section near water washing section one end continuously input flocculating agent step;In mixed washing section near the one end of flocculation section continuously input scrubbing agent step;And, machine-made sand sequentially through mixed washing section, flocculation section, water washing section and dehydration section step.The present application has the advantages of improving the morphology of cob mechanism sand, controlling the content of stone powder, reducing the pH and moisture content, thereby achieving the purpose of reducing the rebound rate of shotcrete, and improving its compressive performance and impermeability.

Description

Technical Field

[0001] This invention relates to the technical field of shotcrete, and in particular to a sand production method based on cobblestone processing into manufactured sand. Background Technology

[0002] The rebound rate of shotcrete refers to the ratio of the amount of shotcrete that fails to adhere to the target surface and rebounds back during the shotcrete construction process to the total amount of shotcrete applied. The rebound rate directly affects construction efficiency, cost, and the final quality of the concrete. In the initial support process of tunnels, over-excavation and under-excavation are significant factors affecting the rebound rate of wet shotcrete. Excessive over-excavation leads to excessive concrete filling space, increasing the rebound rate; while under-excavation may result in insufficient concrete coverage, affecting the support effect. Therefore, reasonable control of over-excavation and under-excavation, optimization of shotcrete mix proportions, strengthened construction management, and control of borehole quality are crucial for reducing the wet shotcrete rebound rate. An investigation by the applicant into the shotcrete application in the initial support of a certain tunnel revealed that the rebound rate of shotcrete using the wet shotcrete construction process was approximately 20-30%. The investigation results show that the rebound rate is one of the main reasons for excessive shotcrete consumption in the initial support of tunnels. During construction, the changes in the rebound rate were found to be mainly influenced by the raw materials, mix proportions, admixtures, shotcrete process, and operator skill level of the shotcrete.

[0003] As an important component of concrete, manufactured sand has a direct impact on the performance of concrete, especially in shotcrete, where the performance of manufactured sand is particularly important. The following are some key performance indicators of manufactured sand and their effects on the rebound rate of shotcrete: (1) Fineness modulus: Fineness modulus is an indicator that characterizes the coarseness of manufactured sand. It has a certain influence on the workability, mechanical properties and long-term durability of concrete. Studies have shown that concrete prepared by manufactured sand has the characteristics of superior river sand concrete in terms of compressive strength, elastic modulus and durability. This shows that manufactured sand with a suitable fineness modulus can improve the performance of concrete, thereby reducing the rebound rate during the construction of shotcrete. (2) Stone powder content: Stone powder content is an important indicator in manufactured sand. Appropriate stone powder has a positive effect on the performance of concrete. Studies have shown that when the stone powder content is 5~10%, the physical properties, mechanical properties and durability of concrete reach the best. This helps to improve the workability and compactness of concrete, thereby reducing the rebound rate during the construction of shotcrete. However, excessive stone powder content may lead to a decrease in the workability of concrete and an increase in the rebound rate. In conclusion, the fineness modulus and stone powder content of manufactured sand are key factors affecting the rebound rate of shotcrete. By reasonably controlling these indicators, the quality and construction efficiency of shotcrete can be effectively improved.

[0004] Pebbles are inherently a green building material, standing out in the field of manufactured sand due to their wear resistance, corrosion resistance, and chemical stability, making them a suitable substitute for manufactured sand. Chinese patent CN107827421A discloses a method for preparing concrete by mixing limestone manufactured sand and pebble manufactured sand, comprising limestone manufactured sand, pebble manufactured sand, and cement. Therefore, the particle size distribution and fineness modulus of the limestone manufactured sand and pebble manufactured sand in the above method can be adjusted. This adjustment can be achieved artificially by selecting crushing equipment and process flow, based on the needs of the project and considering the characteristics of cement and the requirements of concrete. However, natural sand particles are round and smooth, and the fineness modulus of medium sand is mostly 2.6~3.0, which is beneficial to the workability of concrete. On the other hand, the cobblestone manufactured sand obtained by conventional sand making methods has sharp, angular, and rough particles with a fineness modulus mostly above 3.0. The particle size distribution is slightly poor, with more particles larger than 2.5 mm and smaller than 0.08 mm. This results in poor workability of shotcrete, that is, poor fluidity, cohesion and water retention of concrete, which can easily cause defects in the appearance quality of concrete and has a significant impact on the rebound rate, making it more difficult to control the construction quality.

[0005] Chinese Patent CN114195159B discloses a process for preparing high-purity quartz sand using pebbles as raw material. The process involves using pebbles as raw material to produce sand; first, the raw sand is scrubbed under normal pressure with concentrated hydrochloric acid; then, it is scrubbed under high pressure with hydrofluoric acid solution; finally, it is scrubbed under normal pressure with concentrated hydrochloric acid. High-purity carbon powder or silicon carbide is mixed into the resulting quartz sand, which is then chlorinated in a quartz glass chlorination device. Finally, high-purity quartz sand powder with a SiO2 content of 99.99% or higher is obtained. This method obtains high-purity quartz sand through multi-stage scrubbing, meeting the standards for quartz sand used in optical glass. Because the scrubbed quartz sand has uniform particle shape and a small particle size distribution, these characteristics can also improve the density of concrete and reduce its shrinkage rate. However, the high acidity of these quartz sands may react chemically with alkaline substances in cement, producing products that are detrimental to the strength of concrete. This could reduce the compressive strength and durability of the concrete. At the same time, excessive moisture content may lead to uneven evaporation of moisture during the curing process, causing microcracks inside the concrete. These microcracks may expand when the concrete is subjected to external forces, ultimately affecting the rebound rate of the concrete. This needs to be improved. Summary of the Invention

[0006] The problem this invention aims to solve is to provide a sand-making method based on the processing of cobblestones into manufactured sand, addressing the aforementioned shortcomings in existing technologies. This method solves the problems of morphological defects in cobblestone manufactured sand obtained by existing sand-making methods and excessive acidity and water content in cobblestone quartz sand obtained by scrubbing methods. It has the advantages of improving the morphology of cobblestone manufactured sand, controlling stone powder content, and reducing acidity, alkalinity, and water content, thereby achieving the goal of reducing the rebound rate of shotcrete and improving its compressive strength and impermeability.

[0007] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0008] A method for producing manufactured sand based on cobblestones includes a process of obtaining cobblestone masterbatch by screening according to predetermined performance indicators, a process of obtaining crushed stone through jaw crusher and cone crusher, a process of producing sand using crushed stone with predetermined gradation, and a scrubbing and dewatering process, wherein the scrubbing and dewatering process includes...

[0009] The steps of sequentially configuring the washing section, flocculation section and mixed washing section along the water flow path of the integrated washing, sand washing, dewatering and recycling machine are as follows:

[0010] The step of continuously adding flocculant at one end of the flocculation section near the washing section, and controlling the volume concentration of the flocculant to be 0.1~0.3%;

[0011] The step of continuously adding a scrubbing agent at one end of the washing section near the flocculation section, and controlling the volume concentration of the scrubbing agent to be 10-15%; wherein the scrubbing agent is made from the following raw materials by weight percentage: 30-40% plant-based abrasive, 10-15% citric acid, 5-10% behenyl alcohol, 4-6% polyacrylamide, 2-5% polydimethylsiloxane, 1-3% silachlor hydrate, and the balance being water; and,

[0012] The manufactured sand is sequentially passed through the mixing section, flocculation section, water washing section and dewatering section of the integrated washing, sand washing, dewatering and recycling machine.

[0013] By adopting the above technical solution, the sand making method of the present invention not only effectively solves the problem of morphological defects in the cobblestone manufactured sand obtained by existing sand making methods, but also cleverly controls the stone powder content and reduces the acidity and water content of the manufactured sand through the scrubbing and dewatering process, laying a solid foundation for improving the performance of shotcrete. Specifically, the improvement of the above performance indicators is achieved through the following methods:

[0014] First, in the pre-processing stage from screening and crushing to sand making, this invention adopts a processing technology of no less than "two crushing and one shaping" based on dry processing technology, uses advanced processing equipment, and precisely controls the parameters of jaw crusher and cone crusher to ensure a reasonable particle size distribution of crushed stone, providing a high-quality raw material basis for subsequent sand making steps. This process effectively avoids the problem of uneven performance of manufactured sand caused by crushed stone particles that are too large or too small, creating favorable conditions for subsequent performance optimization of manufactured sand.

[0015] Secondly, and most importantly, this invention innovatively designs the scrubbing step in the subsequent process from sand making to scrubbing and dewatering, based on wet processing technology. The scrubbing and dewatering process utilizes an integrated scrubbing, sand washing, dewatering, and recycling machine for high-pressure scrubbing and rapid dewatering of the manufactured sand; specifically,

[0016] An appropriate amount of flocculant is added to the flocculation section. By utilizing the bridging effect of the flocculant, the tiny particles and suspended matter in the manufactured sand are agglomerated into larger clumps, which facilitates subsequent separation. It is worth noting that this invention strictly controls the volume concentration of the flocculant, which ensures the flocculation effect while avoiding the negative impact of excessive use.

[0017] Next, the specially formulated scrubbing agent of this invention is added to the washing section. This scrubbing agent is carefully formulated with a variety of ingredients. Among them, the plant-based scrubbing agent provides the necessary friction for the high-pressure scrubbing of the manufactured sand in water, which not only removes impurities and attachments on the surface of the manufactured sand, but also reduces the presence of sharp edges and rough surfaces. At the same time, citric acid and polyacrylamide, under the action of silachlor hydrate, can form a cross-linked polymer system with the pebble minerals. This system not only enhances the penetration and adhesion of the scrubbing agent, but also effectively adjusts the pH of the manufactured sand surface, reducing the possibility of subsequent alkali-aggregate reaction. Furthermore, based on the addition of behenol and polydimethylsiloxane, not only is the dispersibility and suspension stability of the manufactured sand in water improved, facilitating subsequent washing and dehydration, but a fine lubricating film is also formed on the surface of the above system, promoting the micro-refinement of the particle surface, making the manufactured sand particles more rounded, which helps to reduce the frictional resistance between particles and improve the workability of concrete.

[0018] Therefore, under the combined action of high-pressure water flow and scrubbing agent, the sharp edges of the surface of manufactured sand particles are gradually worn down, the surface roughness is reduced, the particle shape tends to be round, and the fineness modulus is adjusted to be close to the ideal range of natural sand. This process not only improves the morphology of manufactured sand, but also removes some stone powder through physical action, effectively controlling the stone powder content and pH, and avoiding the decline in concrete performance caused by excessive stone powder and excessive acidity.

[0019] Subsequently, the manufactured sand enters the washing section, where it undergoes thorough cleaning using the impact force of the water flow to remove residual scrubbing agents, flocculants, and other impurities. Simultaneously, high-pressure washing helps to further break up particle agglomeration and optimize particle size distribution. This process strictly controls the water flow rate and pressure to ensure effective cleaning without damaging the integrity of the manufactured sand particles.

[0020] Finally, the manufactured sand enters the dewatering zone, where excess water is quickly removed by high-efficiency dewatering equipment, reducing the moisture content to a reasonable range. This process not only improves the dryness of the manufactured sand but also helps reduce micro-cracks caused by uneven moisture evaporation during concrete curing, thereby improving the resilience and durability of the concrete.

[0021] In summary, this invention employs a sand-making method based on cobblestone processing. Through meticulous screening and crushing, innovative sand-making technology, and efficient scrubbing and dewatering processes, it successfully solves the problems of morphological defects, excessive acidity, and high water content found in existing sand-making methods. The prepared manufactured sand not only has excellent morphology, moderate stone powder content, and effectively controlled acidity, alkalinity, and water content, but also significantly improves the rebound rate, compressive strength, and impermeability of shotcrete, providing a strong guarantee for improving the quality of concrete engineering projects.

[0022] Preferably, the scrubbing and dehydration process includes,

[0023] The steps of sequentially configuring the washing section, flocculation section and mixed washing section along the water flow path of the integrated washing, sand washing, dewatering and recycling machine are as follows:

[0024] The step of continuously adding flocculant at one end of the flocculation section near the washing section, and controlling the volume concentration of the flocculant to be 0.1, 0.2, or 0.3%;

[0025] The step of continuously adding a scrubbing agent at one end of the washing section near the flocculation section, and controlling the volume concentration of the scrubbing agent to be 10, 11, 12, 13, 14 or 15%; wherein the scrubbing agent is made from the following raw materials in weight percentages: plant abrasive 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40%, citric acid 10, 11, 12, 13, 14 or 15%, behenol 5, 6, 7, 8, 9 or 10%, polyacrylamide 4, 5 or 6%, polydimethylsiloxane 2, 3, 4 or 5%, silachlor hydrate pyroxene 1, 2 or 3%, and the balance being water; and,

[0026] The manufactured sand is sequentially passed through the mixing section, flocculation section, water washing section and dewatering section of the integrated washing, sand washing, dewatering and recycling machine.

[0027] Preferably, based on optimizing the above-mentioned scrubbing and dewatering process, the present invention can also introduce an intelligent monitoring and automatic adjustment system to further improve sand making efficiency and product quality stability. This system, by integrating sensors, data analysis modules, and automatic control valves, can monitor various key parameters in the scrubbing and dewatering process in real time, such as flocculant concentration, scrubbing agent dosage, water flow rate, dewatering efficiency, and the moisture content of the manufactured sand, and automatically adjust according to preset optimal values ​​to ensure the stability and efficiency of the entire process. Specifically, the workflow of the intelligent monitoring and automatic adjustment system is as follows:

[0028] 1. Install high-precision sensors at key locations in the scrubbing, dewatering, and recycling integrated machine to collect real-time data on flocculant concentration in the flocculation zone, scrubbing agent dosage in the mixing and washing zone, water flow velocity and pressure in the washing zone, and moisture content of manufactured sand in the dewatering zone.

[0029] 2. The collected data is transmitted to the data analysis module in real time. Advanced algorithms are used to process and analyze the data, compare it with the preset optimal parameter range, and evaluate whether the current state deviates from the ideal working condition.

[0030] 3. If the data analysis results show that the current state deviates from the optimal value, the system will automatically trigger the adjustment mechanism; for example, when the flocculant concentration is detected to be too low, the flocculant dosage will be automatically increased; when the scrubbing agent dosage is found to be too high, the dosage will be reduced; if the water flow rate in the washing section is insufficient, the water pump power will be increased to increase the water flow rate; for the dewatering section, if the moisture content of the manufactured sand is too high, the operating parameters of the dewatering equipment will be adjusted, such as increasing the rotation speed or increasing the dewatering time, to ensure the dryness of the final product.

[0031] 4. The system also has self-learning and optimization functions. Through data accumulated over a long period of operation, it continuously adjusts and optimizes the preset optimal parameter range to adapt to changes in the characteristics of different raw materials and production conditions, thereby achieving more precise control.

[0032] In addition, to further improve the scrubbing effect, this invention innovatively designs a rotatable scrubbing device, which is built into the scrubbing, dewatering and recycling integrated machine. It can automatically adjust the scrubbing angle and intensity during the scrubbing process to ensure that the surface of the manufactured sand particles is thoroughly and evenly scrubbed. Combined with an intelligent monitoring and automatic adjustment system, the device can automatically adjust the scrubbing parameters based on real-time feedback data to achieve the best scrubbing effect.

[0033] Furthermore, the scrubbing and dewatering process also includes a step of pre-spraying an oxygen buffer onto the surface of the manufactured sand using atomized spraying, controlling the atomized particle size of the oxygen buffer to be 10~50μm and the spraying rate to be 0.2~1.0L / (min·m²). The oxygen buffer is a solid composition including water, capable of generating a constant oxygen fugacity under fixed temperature and total pressure conditions, and is used in HO systems. This characteristic helps maintain a stable oxygen supply during sand washing, thereby affecting the quality and purity of the sand.

[0034] Furthermore, the oxygen buffer is a HEPES buffer. HEPES buffer has effective buffering capacity at pH values ​​between 6.8 and 8.2, maintaining the acid-base balance of the scrubbing water flow to improve the surface properties of the manufactured sand, such as surface charge and dispersibility, and also helps maintain the stability of the manufactured sand composition.

[0035] Preferably, the scrubbing and dehydration process further includes a step of pre-atomizing and spraying an oxygen buffer onto the surface of the manufactured sand, and controlling the atomized particle size of the oxygen buffer to be 10~15, 15~20, 20~25, 25~30, 30~35, 35~40, 40~45 or 45~50 μm, and the spraying rate to be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0 L / (min·m²).

[0036] Furthermore, the flocculant is a nonionic polyacrylamide flocculant. During sand washing, nonionic polyacrylamide effectively reduces friction between mortar particles and water, lowering the energy generated during particle collisions, thereby reducing sludge production and preventing environmental pollution. In addition, nonionic polyacrylamide can improve sand washing efficiency by reducing the formation of a "calcium sludge" film, enhancing the frictional coating between mortar particles and water, improving the adhesion and dispersibility of mortar particles, thus accelerating the sand washing process, reducing energy consumption, and shortening processing time.

[0037] Furthermore, the plant-based abrasive is made from raw materials comprising the following parts by weight: 10-13 parts walnut shell powder and 9-12 parts apricot seed powder.

[0038] Furthermore, the plant-based abrasive also includes 6-8 parts of coconut shell powder.

[0039] Furthermore, the plant-based abrasive also includes 5-7 parts of aloe vera leaf powder.

[0040] Furthermore, the plant-based abrasive is made from the following raw materials in parts by weight: 10, 11, 12 or 13 parts walnut shell powder, 9, 10, 11 or 12 parts apricot seed powder, 6, 7 or 8 parts coconut shell powder, and 5, 6 or 7 parts aloe vera leaf powder.

[0041] The plant-based abrasive uses walnut (Juglans reggae) shell powder and apricot (Prunus armeniaca) seed powder as the main abrasive particles. During the scrubbing process, these particles, along with stone powder and abrasive grains, finely grind the surface of the machine-made abrasive, significantly improving its surface smoothness and the bonding strength between particles. In addition, the added coconut shell powder not only enhances the hardness and abrasion resistance of the abrasive but also, due to its natural porous structure, helps to adsorb and remove tiny impurities from the surface of the machine-made abrasive, further improving the cleaning effect. The addition of aloe vera leaf powder utilizes its various active ingredients, such as polysaccharides, vitamins, and minerals, to gently nourish and protect the surface of the machine-made abrasive, reducing surface damage that may be caused by excessive scrubbing and maintaining the natural color and texture of the abrasive grains.

[0042] Furthermore, the specific implementation method of obtaining pebble masterbatch according to predetermined performance indicators is as follows: First, pebbles with the following characteristics are selected as masterbatch: crushing index <16%, soundness (mass loss value after 5 cycles of sodium sulfate solution method) <8%, water absorption rate <2.0%, needle-like and flaky particle content <15%, mud content <1.0%, mud lump content <0.5%, organic matter content (colorimetric method) qualified, sulfide and sulfate content (based on SO3 mass) <1.0%, rock compressive strength (water saturated state) >30MPa, apparent density >2500kg / m³, loose bulk density >1350kg / m³, and porosity <47%. Then, pebble masterbatch with a particle size of less than 80mm is screened by a bar vibrating feeder and fed to a jaw crusher, while pebble masterbatch with a particle size greater than 80mm is output as waste residue.

[0043] Furthermore, the specific implementation of the process of obtaining crushed stone through jaw crusher and cone crusher is as follows: first, the coarse crusher crushes the pebble masterbatch to below 80mm, then the cone crusher crushes the coarsely crushed pebble masterbatch through medium and fine crushing, and the finely crushed pebble masterbatch is screened by a vibrating screen to obtain crushed stone of various particle size ranges (20~40mm, 10~20mm, 16~25mm). The crushed stone that meets the particle size requirements is transported to the silo, and the crushed stone that does not meet the particle size requirements is transported to the cone crusher for further crushing, forming a closed-loop multi-cycle crushing process.

[0044] Furthermore, the specific implementation of the process of using pre-graded crushed stone for sand making is as follows: crushed stone with a particle size of 5~15mm and crushed stone with a particle size of <5mm are mixed in a ratio of 5~8:4~9 in the silo, and then transported to the sand making machine for sand making operation. The crushed manufactured sand is then transported to the integrated machine for scrubbing, washing, dewatering and recycling.

[0045] In summary, the beneficial technical effects of this invention are as follows: This invention adopts a sand-making method based on the processing of pebbles into manufactured sand. Through fine screening and crushing, innovative sand-making technology, and efficient scrubbing and dewatering processes, it successfully solves the problems of morphological defects, excessive acidity, and excessive water content existing in existing sand-making methods. The manufactured sand prepared not only has excellent morphology, moderate stone powder content, and effectively controlled acidity, alkalinity, and water content, but also significantly improves the rebound rate, compressive strength, and impermeability of shotcrete, providing a strong guarantee for improving the quality of concrete engineering. Attached Figure Description

[0046] Figure 1 This is a flowchart of the sand making method provided in Embodiment 1 of the present invention.

[0047] Figure 2 This is a schematic diagram of the sand and gravel production chain in Embodiment 2 of the present invention. Detailed Implementation

[0048] To make the technical means, creative features, objectives and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0049] Example 1: Refer to Figure 1 The present invention discloses a sand making method based on cobblestone processing, which includes a process of obtaining cobblestone masterbatch by screening according to predetermined performance indicators, a process of obtaining crushed stone by jaw crusher and cone crusher, a process of making sand using crushed stone with predetermined gradation, and a process of scrubbing and dewatering.

[0050] Example 2: Refer to Figure 2 This invention discloses a sand-making method based on cobblestone processing, which differs from Example 1 in that it further discloses a sand and gravel production chain matched with the sand-making method. This chain includes a bar-type vibrating feeder, a soil removal screen, a jaw crusher, a cone crusher, a sand making machine, a scrubbing, washing, dewatering, and recycling integrated machine, four vibrating screens, multiple dust collectors, and multiple silos. These devices are connected by sand and gravel conveyors and can be equipped with an intelligent monitoring and automatic adjustment system. Their models, quantities, and production capacities are shown in Table 1.

[0051] Table 1

[0052] Equipment Name model quantity Production capacity (t / h) bar vibrating feeder SZ1360 1 30 Jaw crusher SJ1200 1 132 Soil removal screen 2SS1860 1 18.5 Cone Crusher Feeder SW1220 2 30 cone crusher SCH5000 STD C 1 400 Sand making machine SV10DR630 1 630 Integrated machine for scrubbing, washing, sanding, dewatering and recycling GSB2000 2 Adjust according to the sand making machine vibrating screen 2SS3075 4 120 dust collector YQM128-7 1 93

[0053] The sand-making method of this invention not only effectively solves the problem of morphological defects in the cobblestone manufactured sand obtained by existing sand-making methods, but also cleverly controls the stone powder content and reduces the acidity and water content of the manufactured sand through the scrubbing and dehydration process, laying a solid foundation for improving the performance of shotcrete. Specifically, the improvement of the above-mentioned performance indicators is achieved through the following methods:

[0054] (1) Sand making tower integrated machine: The sand making tower integrates the sand and gravel production chain. In order to meet the high reliability and high efficiency requirements of high-quality sand and gravel yards, cement plants, mixing plants, etc., it integrates advanced crushing, screening, dust removal, powder selection and intelligent control technologies. The complete set of equipment integrated machine has the characteristics of good cleaning effect, humanized design, wear resistance and reliability, good quality of finished materials, reasonable structure and small footprint.

[0055] (2) Scrubbing, washing, dewatering and recycling integrated machine: During the scrubbing and dewatering process, the manufactured sand after being sprayed with oxygen buffer first passes through the flocculation section of the scrubbing, washing, dewatering and recycling integrated machine to scrub off the mud powder attached to the surface of the sand particles; the scrubbed material enters the mixing section and water washing section for secondary wheel washing; the overflow water in the scrubbing, washing, dewatering and recycling integrated machine enters the auxiliary water tank and then enters the hydrocyclone for the first fine sand recovery, while the mud water in the scrubbing and washing process overflows from the hydrocyclone backflow outlet to the tailwater treatment system; the coarse and fine sand after scrubbing and washing enters the dewatering screen for dewatering, and the water in the dewatering screen lower water tank is pumped into the hydrocyclone for the second fine sand recovery, while the mud water overflows from the hydrocyclone backflow outlet to the sewage treatment system;

[0056] (3) Dust removal and recycling system: The production line adopts a closed workshop and introduces offline pulse dust removal technology and equipment, which greatly improves the dust removal and cleaning effect. It adopts a closed dust conveying line and is equipped with a PLC controller to automatically control the operation of the dust collector. High-pressure atomizing nozzles are installed at the material pouring point of the raw material silo, the transfer silo and the material drop point of the finished product silo to suppress dust during material drop. The operation is convenient and prevents secondary dust.

[0057] (4) Waste residue cake: Using scientific management methods, a circulating drainage system is set up for the existing stone crushing plant and mixing plant. With a five-stage sedimentation tank, wastewater and sewage are recycled. Advanced sewage treatment equipment is used to treat and recycle the wastewater generated by the mixing plant, saving water resources, realizing energy-saving, low-carbon and pollution-free construction, and improving the low-carbon and environmental protection management level of the project.

[0058] (5) Water purification equipment: The effluent from the plate and frame filter press flows into the clear water tank through the pipeline, and is then pumped into the integrated sewage treatment device. Special concrete water purification agent is added for neutralization and adjustment, coagulation and sedimentation, mechanical filtration and other comprehensive treatments. The effluent not only meets the requirements for direct discharge, but can also be directly reused for cleaning in the station, ultimately achieving zero discharge of sewage and waste.

[0059] (6) Cloud weighing: The hardware equipment used in the project can be connected to the cloud weighing system. The system can connect to weighbridges, platform scales, batching weighing, filling weighing, loader scales, portable axle weighing scales, etc. The weighbridge readings are read into the system in real time, realizing data storage, query, analysis, statistics, export and printing of various weighing equipment. This avoids weighing data errors caused by human negligence or human error, improves data accuracy, reduces human intervention and saves labor costs.

[0060] (7) Material data collection and statistics: The production quality of raw materials should be mainly controlled by automatic equipment and supplemented by manual quality sampling; establish a quality inspection laboratory, set up full-time quality inspectors, equip it with testing equipment, test product quality in a timely manner and issue product quality qualification certificates; establish a product quality management system and archive product quality documents;

[0061] (8) Main functions of construction machinery and equipment:

[0062] a) It has a visual central control function and an automatic iron removal function, and can simultaneously produce unshaped crushed stone, shaped crushed stone and manufactured sand.

[0063] b) The main processing equipment of the production line is configured with jaw crusher + multi-cylinder hydraulic cone crusher + impact crusher (shaping, sand making).

[0064] c) The production line must have the function of primary crushing and screening, as well as the function of crushing and sand making from crushed stone and the function of discharging finished crushed stone products in 5 grades.

[0065] d) The production line is fully equipped with a water mist dust removal system, a pulse exhaust dust removal system, and a sand and powder separator. All components and belt conveyors are sealed for dust removal to ensure that the powder content of crushed stone and manufactured sand meets the requirements. An independent powder recovery tank (tank capacity not less than 100T) is also set up.

[0066] e) The equipment is selected for modular assembly, which facilitates installation, disassembly, and transportation.

[0067] f) Before the construction of the aggregate production line begins, all mechanical equipment should be inspected, tested, and calibrated to meet construction requirements and avoid malfunctions that could affect construction. In particular, the intelligent monitoring system must be regularly maintained and inspected to prevent equipment failures or human error from affecting concrete quality.

[0068] Example 3: This invention discloses a method for producing manufactured sand based on cobblestones. The difference from Example 2 lies in the specific implementation of the process of obtaining cobblestone masterbatch according to predetermined performance indicators. First, cobblestones with the following characteristics are selected as masterbatch: crushing index <16%, soundness (mass loss value after 5 cycles using sodium sulfate solution method) <8%, water absorption <2.0%, needle-like / flaky particle content <15%, mud content <1.0%, mud lump content <0.5%, qualified organic matter content (colorimetric method), sulfide and sulfate content (based on SO3 mass) <1.0%, rock compressive strength (water saturated state) >30MPa, apparent density >2500kg / m³, loose bulk density >1350kg / m³, and porosity <47%. Then, a bar-type vibrating feeder screens out cobblestone masterbatch with a particle size below 80mm, and feeds it to a jaw crusher. Cobblestone masterbatch with a particle size exceeding 80mm is output as waste.

[0069] Example 4: This invention discloses a method for producing manufactured sand based on cobblestones. The difference from Example 2 is that the specific implementation of the process of obtaining crushed stone through jaw crusher and cone crusher is as follows: First, the cobblestone raw material is coarsely crushed to below 80mm by a jaw crusher. Then, the coarsely crushed cobblestone raw material is subjected to medium and fine crushing by a cone crusher. The finely crushed cobblestone raw material is screened by a vibrating screen to obtain crushed stone of various particle size ranges (20~40mm, 10~20mm, 16~25mm). The crushed stone that meets the particle size requirements is transported to the silo, and the crushed stone that does not meet the particle size requirements is transported to the cone crusher for further crushing, forming a closed-loop multi-cycle crushing process.

[0070] Example 5: This invention discloses a method for making manufactured sand based on cobblestones. The difference from Example 2 is that the specific implementation of the sand making process using pre-graded crushed stone is as follows: crushed stone with a particle size of 5-15mm and crushed stone with a particle size of <5mm are mixed in a ratio of 6:8 in the silo and then transported to the sand making machine for sand making. The crushed manufactured sand is then transported to an integrated machine for scrubbing, washing, dewatering and recycling.

[0071] Example 6: This invention discloses a method for producing manufactured sand based on pebbles. The difference from Example 2 is that the scrubbing and dewatering process includes...

[0072] The steps of sequentially configuring the washing section, flocculation section and mixed washing section along the water flow path of the integrated washing, sand washing, dewatering and recycling machine are as follows:

[0073] The step involves continuously adding nonionic polyacrylamide flocculant (NPAM) to one end of the flocculation section near the washing section, and controlling the volume concentration of the nonionic polyacrylamide flocculant at 0.20%.

[0074] The step of continuously adding scrubbing agent at one end of the washing section near the flocculation section, and controlling the volume concentration of the scrubbing agent to be 12.8%; wherein, the scrubbing agent is made from the following raw materials by weight percentage: walnut shell powder 11.5%, apricot seed powder 10.3%, coconut shell powder 7.0%, aloe vera leaf powder 6.0%, citric acid 13.0%, behenol 7.8%, polyacrylamide 5.0%, polydimethylsiloxane 4.0%, silachlor hydrate pyroxene 2.0%, and the balance being water;

[0075] The step of pre-spraying HEPES buffer onto the surface of manufactured sand by atomization, controlling the atomized particle size of the HEPES buffer to be 20~30μm and the spraying rate to be 0.5L / (min·m²); and,

[0076] The manufactured sand is sequentially passed through the mixing section, flocculation section, water washing section and dewatering section of the integrated washing, sand washing, dewatering and recycling machine.

[0077] Examples 7-10: These are sand-making methods based on cobblestone processing of manufactured sand disclosed in this invention. The difference from Example 6 is that the amount of reagent used in each step of the scrubbing process is shown in Table 2.

[0078] Table 2

[0079] Example 6 Example 7 Example 8 Example 9 Example 10 NPAM (%v / v) 0.20 0.10 0.30 0.15 0.28 Cleaning agent (%v / v) 12.8 10.0 15.0 11.0 14.0 Walnut shell powder (%) 11.5 10.0 13.0 10.5 12.5 Apricot seed powder (%) 10.3 9.0 12.0 9.5 11.5 Coconut shell powder (%) 7.0 6.0 8.0 6.5 7.5 Curacao aloe vera leaf powder (%) 6.0 5.0 7.0 5.5 6.5 Citric acid (%) 13.0 10.0 15.0 12.0 14.0 Betaine alcohol (%) 7.8 5.0 10.0 6.0 8.0 Polyacrylamide (%) 5.0 4.0 6.0 4.5 5.5 Polydimethylsiloxane (%) 4.0 2.0 5.0 3.0 4.5 Silachlorite (%) 2.0 1.0 3.0 1.5 2.5

[0080] Comparative Examples 1-5: These are sand-making methods based on cobblestone processing of manufactured sand disclosed in this invention. The difference from Example 6 is that the amount of reagent used in each step of the scrubbing process is shown in Table 3.

[0081] Table 3

[0082] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 NPAM (%v / v) 0.20 0.20 0.20 0.20 0.20 Cleaning agent (%v / v) 0 12.8 12.8 12.8 12.8 Walnut shell powder (%) 11.5 0 11.5 11.5 11.5 Apricot seed powder (%) 10.3 0 10.3 10.3 10.3 Coconut shell powder (%) 7.0 0 7.0 7.0 7.0 Curacao aloe vera leaf powder (%) 6.0 0 6.0 6.0 6.0 Citric acid (%) 13.0 13.0 0 13.0 13.0 Betaine alcohol (%) 7.8 7.8 7.8 7.8 0 Polyacrylamide (%) 5.0 5.0 0 5.0 5.0 Polydimethylsiloxane (%) 4.0 4.0 4.0 0 4.0 Silachlorite (%) 2.0 2.0 0 2.0 2.0

[0083] Example 1: The performance of the prepared manufactured sand was tested. The manufactured sand after scrubbing and dehydration should meet the technical requirements in Table 4.

[0084] Table 4

[0085]

[0086] Among them, the manufactured sand prepared by the scrubbing and dehydration method according to Examples 6 to 10 was tested for processing stability. Among them, the fineness modulus, stone powder content, gradation and methylene blue value should be sampled 10 times consecutively, and at least 9 of them should differ from the average value of the sampled sand by no more than ±0.2, ±2%, ±5% and ±0.3 respectively. The average values ​​of each test data are shown in Table 5.

[0087] Table 5

[0088] Example 6 Example 7 Example 8 Example 9 Example 10 Grading meets Zone II requirements conform to conform to conform to conform to conform to Fineness Modulus 2.88 2.82 2.91 2.85 2.88 Bulk density (kg / m³) 1451 1462 1471 1460 1441 Apparent density (kg / m³) ＞2500 ＞2500 ＞2500 ＞2500 ＞2500 Methylene blue value (g / cm³) 1.2 1.0 1.0 1.2 0.8 Stone powder content (%) 4.2 4.0 3.6 4.2 3.5 Content of flaky particles (%) 2.0 1.5 1.5 1.1 2.2 Water absorption rate (%) 1.2 1.2 1.0 1.2 1.1

[0089] Experimental Example 2: Preparation of C20 shotcrete samples. The shotcrete consisted of the following raw materials by weight: 460 parts cement; 69 parts fly ash; 906 parts manufactured sand; 880 parts crushed stone; 20 parts admixture; and 207 parts water.

[0090] 1) Cement: P.Ⅱ52.5 Portland cement;

[0091] 2) Fly ash: Class F, Grade I fly ash;

[0092] 3) Manufactured sand: prepared according to the method of Example 6 or Comparative Examples 1 to 5, comprising 0.3% sand particles with a particle size of 4.75 mm or larger, 13.2% sand particles with a particle size of 4.75 to 2.36 mm, 22.8% sand particles with a particle size of 2.36 to 1.18 mm, 20.5% sand particles with a particle size of 1.18 to 0.60 mm, 24.0% sand particles with a particle size of 0.30 to 0.60 mm, and 19.2% sand particles with a particle size of less than 0.15 mm;

[0093] 4) Crushed stone: prepared according to the methods of Examples 1 to 5, comprising 70% large crushed stone of 9.5 to 19 mm and 30% small crushed stone of 4.75 to 9.5 mm. The crushed stone meets the required strength and firmness, meets the required content of needle-like and flaky particles, and adheres to level 4.

[0094] 5) Polycarboxylate superplasticizer: purchased from Zhejiang Jiaogong New Materials Co., Ltd.;

[0095] The prepared sprayed concrete samples were tested for performance according to relevant standards. The tests were performed three times and the average value was taken. The test results are shown in Table 6.

[0096] In addition, to avoid the influence of operator skill, wet spraying operators must first undergo pre-job training, be certified, and receive regular safety briefings. The spraying air velocity, the amount of water added to the nozzle, the distance between the nozzle and the sprayed surface, and the appropriateness of the spraying angle directly affect the rebound rate during shotcreting. Too large or too small a distance between the nozzle and the sprayed surface will increase the rebound rate. When spraying concrete, the nozzle should be kept as perpendicular as possible to the sprayed rock surface and slightly angled towards the initial spraying point (the tilt angle should be controlled within 10°). If the angle between the nozzle and the sprayed surface is too small, the sprayed material will roll on the sprayed surface, creating an uneven, wavy spray surface, increasing the rebound rate, and affecting the quality of the shotcrete.

[0097] Table 6

[0098] Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Rebound rate (%) 2.1 22.5 25.3 18.2 5.5 8.6 28-day compressive strength (MPa) 28.3 29.5 12.8 17.2 25.8 24.7 28-day flexural strength (MPa) 4.8 3.5 5.0 4.6 4.9 4.3 28-day tensile strength (MPa) 3.5 3.2 2.8 2.5 3.1 3.1 28-day seepage height (mm) 52.4 26.2 38.4 48.6 29.7 34.5 28-day carbonization depth (mm) 15 12 8 12 15 13 Bond strength (MPa) 3.5 2.0 1.9 0.8 1.8 2.4

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing manufactured sand based on cobblestones, comprising a process of obtaining cobblestone masterbatch by screening according to predetermined performance indicators, a process of obtaining crushed stone by jaw crusher and cone crusher, a process of producing sand using crushed stone of predetermined gradation, and a process of scrubbing and dewatering, characterized in that: The scrubbing and dehydration process includes, The steps of sequentially configuring the washing section, flocculation section and mixed washing section along the water flow path of the integrated washing, sand washing, dewatering and recycling machine are as follows: The step of continuously adding flocculant at one end of the flocculation section near the washing section, and controlling the volume concentration of the flocculant to be 0.1~0.3%; The step of continuously adding a scrubbing agent at one end of the washing section near the flocculation section, and controlling the volume concentration of the scrubbing agent to be 10-15%; wherein the scrubbing agent is made from the following raw materials by weight percentage: 30-40% plant-based abrasive, 10-15% citric acid, 5-10% behenyl alcohol, 4-6% polyacrylamide, 2-5% polydimethylsiloxane, 1-3% silachlor hydrate, and the balance being water; and, The manufactured sand is sequentially passed through the mixing section, flocculation section, water washing section and dewatering section of the integrated washing, sand washing, dewatering and recycling machine.

2. The sand making method based on cobblestone processing for manufactured sand according to claim 1, characterized in that: The scrubbing and dehydration process also includes a step of pre-spraying an oxygen buffer onto the surface of the manufactured sand, and controlling the atomized particle size of the oxygen buffer to be 10~50μm and the spraying volume to be 0.2~1.0L / (min·㎡).

3. The sand making method based on cobblestone processing for manufactured sand according to claim 2, characterized in that: The oxygen buffer is a HEPES buffer.

4. The sand making method based on cobblestone processing for manufactured sand according to claim 1, characterized in that: The flocculant is a nonionic polyacrylamide flocculant.

5. A method for producing manufactured sand based on cobblestones according to claim 1, characterized in that: The plant-based abrasive is made from the following raw materials in parts by weight: 10-13 parts walnut shell powder and 9-12 parts apricot seed powder.

6. A method for producing manufactured sand based on cobblestones according to claim 5, characterized in that: The plant-based abrasive also includes 6-8 parts of coconut shell powder.

7. A method for producing manufactured sand based on cobblestones according to claim 5, characterized in that: The plant-based abrasive also includes 5-7 parts of aloe vera leaf powder.

8. A method for producing manufactured sand based on cobblestones according to claim 1, characterized in that: The specific implementation method of obtaining pebble masterbatch according to predetermined performance indicators is as follows: First, pebbles with crushing index <16%, soundness <8%, water absorption <2.0%, needle-like and flaky particle content <15%, mud content <1.0%, mud lump content <0.5%, qualified organic matter content, sulfide and sulfate content <1.0%, rock compressive strength >30MPa, apparent density >2500kg / m³, loose bulk density >1350kg / m³, and porosity <47% are selected as masterbatch. Then, the pebble masterbatch with a particle size of less than 80mm is screened by a bar vibrating feeder and fed to a jaw crusher, while the pebble masterbatch with a particle size of more than 80mm is output as waste.

9. A method for producing manufactured sand based on cobblestones according to claim 8, characterized in that: The specific implementation of the process of obtaining crushed stone through jaw crusher and cone crusher is as follows: first, the coarse crusher crushes the pebble masterbatch to below 80mm, then the cone crusher crushes the coarsely crushed pebble masterbatch into medium and fine crushing, and the finely crushed pebble masterbatch is screened by a vibrating screen to obtain crushed stone of various particle size ranges. The crushed stone that meets the particle size requirements is transported to the silo, and the crushed stone that does not meet the particle size requirements is transported to the cone crusher for further crushing, forming a closed-loop multi-cycle crushing.

10. A method for producing manufactured sand based on cobblestones according to claim 9, characterized in that: The specific implementation method of the process of making sand using pre-graded crushed stone is as follows: crushed stone with a particle size of 5~15mm and crushed stone with a particle size of <5mm are mixed in a ratio of 5~8:4~9 in the silo, and then transported to the sand making machine for sand making operation. The crushed manufactured sand is then transported to the integrated machine for scrubbing, washing, dewatering and recycling.

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