A wet-process sand and stone powder activity excitation lithifying agent and its application in the preparation of recycled aggregates

Abstract

The present invention discloses a wet-process sand powder activity excitation lithifying agent and its application in the preparation of recycled aggregate. The sand powder activity excitation lithifying agent comprises 5-10 parts by mass of a flocculant degradation component, 1-3 parts by mass of a surface active component, and 15-20 parts by mass of a sand powder inorganic cementing component; the flocculant degradation component is an NaOH or KOH solution with a molar concentration of 2 mol / L to 5 mol / L; the surface active component is sodium dodecyl sulfate or octylphenol polyoxyethylene ether with a molar concentration of 0.01 mol / L to 0.1 mol / L; the sand powder inorganic cementing component is a solution prepared by mixing sodium silicate with a modulus of 1.0 to 1.5, ultrafine slag powder with a specific surface area ≥ 600 m2 / kg, an activity index ≥ 120%, and a fineness D90 below 10 μm, and water in a mass ratio of (3-5):(0.5-1):(8-10). The present invention fully activates the activity of sand powder by using the lithifying agent, and uses the sand powder as a cementitious material to prepare recycled aggregate. Because it coagulates and hardens during the agglomeration process, the particle morphology of the recycled aggregate is more excellent than that of traditional machine-made aggregate, its soundness ≤ 8.0%, and the single-stage maximum crushing index ≤ 25%.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and specifically relates to a wet-processed sand and stone powder activity-exciting lithifying agent and its application in the preparation of recycled aggregate. Background Art

[0002] The production process of manufactured sand is mainly divided into dry process and wet process. At present, there is no reasonable and unified recycled utilization technology system for the stone powder generated in the production process of wet-processed manufactured sand. Usually, the stone powder generated in the production process of wet-processed manufactured sand is collected by repeated washing and drying. The patent "High-efficiency Recycling Process for Ultra-fine Particles in Circulating Water of Wet-processed Manufactured Sand (CN 117088562A)" obtains clean fine sand and stone powder particles through multiple cleaning and precipitation. The patent "Method for Recycling Waste Stone Powder in a Wet-processed Sand and Gravel Production System (CN 102430467 A)" aims at the waste stone powder generated in the production process of wet-processed manufactured sand, and after re-washing and drying, it is re-added to the manufactured aggregate to realize the recycling of waste stone powder. However, directly adding it to the manufactured aggregate after washing and drying easily causes the performance of the concrete prepared therefrom to decrease.

[0003] The main reason for the poor utilization performance of the existing inventions for stone powder is that only the stone powder is used as a filler to prepare aggregate or concrete, and too much stone powder without reaction activity is equivalent to artificially introducing defects therein, resulting in a significant decrease in the performance of the aggregate or concrete prepared with stone powder compared with conventional materials.

[0004] Therefore, how to use wet-processed sand and stone powder to prepare recycled aggregate for concrete that meets the performance requirements is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a wet-processed sand and stone powder activity-exciting lithifying agent and its application in the preparation of recycled aggregate. The recycled aggregate prepared from stone powder in the present invention realizes the efficient recycling of wet-processed sand and stone powder, and improves the economic benefits of manufactured sand production.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A wet-processed sand and stone powder activity-exciting lithifying agent, comprising 5-10 parts by mass of a flocculant degradation component, 1-3 parts by mass of a surface active component, and 15-20 parts by mass of a stone powder inorganic cementing component;

[0008] The flocculant degradation component is a NaOH or KOH solution with a molar concentration of 2 mol / L to 5 mol / L;

[0009] The surface active component is sodium dodecyl sulfate or octylphenol polyoxyethylene ether with a molar concentration of 0.01 mol / L to 0.1 mol / L;

[0010] The inorganic binder component of the stone powder is a solution prepared by mixing sodium silicate with a modulus of 1.0 to 1.5, ultrafine slag powder with a specific surface area of ≥600 m 2 / kg, an activity index of ≥120%, and a fineness D90 of less than 10 μm, and water in a mass ratio of (3 - 5):(0.5 - 1):(8 - 10).

[0011] Application of a wet-process sand-making stone powder activity activator in the preparation of recycled aggregate from wet-process sand-making stone powder.

[0012] A method for preparing recycled aggregate from wet-process sand-making stone powder, specifically including the following steps:

[0013] Step 1: Add a degradable lignin-based water-soluble flocculant to the stone powder slurry produced by wet sand-making for flocculation precipitation, and drain the upper clear water after complete precipitation;

[0014] Step 2: Use the ultrasonic stirring and flocculation device to ultrasonically stir and flocculate the stone powder obtained by wet sand-making to accelerate the coagulation of the stone powder under the action of the degradable lignin-based water-soluble polymer flocculant;

[0015] Step 3: Add a stone powder activity activator to the flocculated stone powder to prepare a preliminarily formed recycled aggregate with a certain strength;

[0016] Step 4: Filter out the preliminarily formed recycled aggregate from the activator, and use the electromagnetic wave energy directional excitation device to accelerate the hardening of the aggregate again, and obtain recycled aggregates with different particle sizes after screening.

[0017] Preferably, in Step 2, the stirring time of ultrasonic stirring and flocculation is 30 s - 60 s, and the ultrasonic stirring power is 1000 W - 1500 W.

[0018] Preferably, in Step 3, 5% - 10% of the activator based on the total amount of stone powder is added.

[0019] Preferably, the working parameters of electromagnetic wave energy directional excitation in Step 4; the screening uses a high-frequency vibration screening device to screen the hardened recycled aggregate into recycled aggregates with different particle sizes of 0.15 mm - 0.30 mm, 0.30 mm - 0.60 mm, 0.60 mm - 1.18 mm, 1.18 mm - 2.36 mm, 2.36 mm - 4.75 mm, 5.00 mm - 10.00 mm, and 10.00 mm - 20.00 mm.

[0020] Preferably, the device for preparing recycled aggregate from wet-process sand-making stone powder includes: a stone powder flocculation precipitation device, an ultrasonic stirring and flocculation device, a vacuum adsorption and filtration device, an electromagnetic wave energy directional excitation device, and a high-frequency vibration screening device.

[0021] The stone powder flocculation precipitation device is used to put the degradable lignin-based water-soluble polymer flocculant into the stone powder slurry to achieve the flocculation precipitation of stone powder;

[0022] The ultrasonic stirring flocculation device uses the high-frequency vibration of ultrasonic waves to achieve the irregular vibration stirring of stone powder after adding the degradable lignin-based water-soluble polymer flocculant, accelerating the process of flocculation and agglomeration of stone powder;

[0023] The vacuum adsorption filtration device uses vacuum negative pressure to remove the purified water part after the flocculation precipitation of stone powder;

[0024] The electromagnetic wave energy directional excitation device uses the principle of the rearrangement of dipoles in the electromagnetic field to achieve the oscillation of molecules at a speed of up to hundreds of millions of times per second, further exciting the molecular activity in the stone powder and the lithifying agent, accelerating the polymerization and hardening process of the stone powder under the action of the lithifying agent, and completely degrading the degradable lignin-based water-soluble polymer.

[0025] Preferably, the stone powder flocculation precipitation device includes: a degradable lignin-based water-soluble flocculant feeder (1), a stone powder storage bin (15), a wet-process sand and stone powder feeding device (2), and a purified water drain port (16);

[0026] The ultrasonic stirring flocculation device includes an ultrasonic oscillator (12), an ultrasonic vibration generator (7), and a control panel (6); the ultrasonic oscillator is the core component for generating ultrasonic waves, made of piezoelectric ceramic material, and capable of converting electrical energy into ultrasonic vibration; the ultrasonic vibration generator generates high-frequency electrical signals and transmits them to the ultrasonic oscillator to drive the ultrasonic oscillator to generate ultrasonic vibration; the control panel is used to set the working parameters of the ultrasonic stirring flocculation device, such as stirring time, stirring rate, etc.;

[0027] The vacuum adsorption filtration device includes a purification filter (14), a vacuum adsorption conduit (13), a vacuum dehydration storage device (10), and a high-power vacuum pump (11); the purification filter is composed of a filter screen with a pore diameter less than 0.15 mm, used to filter the wastewater generated after the flocculation of stone powder and the powder particles that have not agglomerated; the vacuum adsorption conduit is used to connect the purification filter and the vacuum dehydration storage device; the vacuum dehydration storage device is used to collect the liquid discharged by vacuum dehydration; the high-power vacuum pump has a power range of 100 W to 500 W and can provide a negative pressure of 0 to 1.0 MPa;

[0028] The electromagnetic wave energy directional excitation device includes an electromagnetic wave energy generator (4) and an electromagnetic wave energy directional transmission device (5); the electromagnetic wave energy generator generates high-frequency electromagnetic waves through an oscillator and then converts them into microwave energy; the electromagnetic wave energy directional transmission device is the part that controls the transmission of microwave energy, specifically including components such as waveguides, transmission lines, or microwave antennas, and can effectively transmit the microwave energy to the stone powder under the action of the lithifying agent.

[0029] The high-frequency vibration screening device includes square-hole sieves 7 with apertures of 20mm, 10mm, 4.75mm, 2.36mm, 1.18mm, 600μm, 300μm, and 150μm stacked from high to low, and a high-frequency vibration tray and a high-frequency vibration base are installed at the bottom, enabling the high-frequency vibration screening device to perform screening at a frequency of 2,000 to 5,000 times per minute.

[0030] From the above technical solutions, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The performance of the recycled aggregate made from stone powder is the same as that of the machine-made aggregate: The present invention uses a lithifying agent to fully activate the activity of stone powder, takes the stone powder as a cementitious material, and combines an electromagnetic wave energy directional excitation device to accelerate the movement rate of lithifying agent molecules, enabling the stone powder to directly coagulate and harden into lumps in wastewater. The recycled aggregate made from stone powder prepared by the present invention has a more excellent particle morphology than traditional machine-made aggregates due to its coagulation and hardening during the agglomeration process, with its soundness ≤ 8.0% and the single-stage maximum crushing index ≤ 25%.

[0032] 2. Synchronous production of stone powder during wet sand making: The recycled aggregate made from stone powder proposed by the present invention is directly carried out in the wastewater generated during the wet machine-made sand production process throughout the whole process, without the need to pre-clean and dry the stone powder in advance; the wet machine-made sand stone powder to aggregate device of the present invention realizes the synchronous production of stone powder during wet sand making.

[0033] 3. Solve the problem of a large amount of flocculant remaining in stone powder: The present invention uses a degradable lignin-based water-soluble polymer flocculant to replace the commonly used polyacrylamide flocculant, which is rapidly degraded under the action of the degradation components of the flocculant, eliminating the influence of the flocculant on the structural performance of the subsequent recycled aggregate made from stone powder. Description of the Drawings

[0034] Figure 1 It is a schematic diagram of the device for preparing recycled aggregate from stone powder in wet machine-made sand in an embodiment of the present invention. Detailed Embodiments

[0035] The following describes the embodiments of the present invention. The examples of the embodiments are shown in the drawings. The embodiments described with reference to the drawings are exemplary and are intended to explain the present invention, rather than being construed as a limitation to the present invention.

[0036] As Figure 1 shown, the device used in the method for preparing recycled aggregate from wet-processed sand and stone powder in the embodiments of the present invention includes: a stone powder flocculation precipitation device, an ultrasonic stirring flocculation device, a vacuum adsorption filtration device, an electromagnetic wave energy directional excitation device, and a high-frequency vibration screening device.

[0037] The stone powder flocculation precipitation device includes: a degradable lignin-based water-soluble polymer coagulant feeder (1), a stone powder storage bin (15), a wet-processed sand and stone powder feeding device (2), and a purified water drainage port (16);

[0038] The ultrasonic stirring flocculation device includes an ultrasonic oscillator (12) and a control panel assembly (6);

[0039] The vacuum adsorption filtration device includes a purification filter (14), a vacuum adsorption conduit (13), a vacuum dehydration storage device (10), and a high-power vacuum pump (11);

[0040] The electromagnetic wave energy directional excitation device includes an electromagnetic wave energy generator (4) and an electromagnetic wave energy directional transmission device (5); an electromagnetic wave energy directional excitation device protection device (3) is provided outside the electromagnetic wave energy directional excitation device;

[0041] The high-frequency vibration screening device includes square-hole sieves 7 with apertures of 20 mm, 10 mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 μm, 300 μm, and 150 μm stacked from high to low, and a high-frequency vibration tray (8) and a high-frequency vibration base (9) are installed at the bottom, enabling the high-frequency vibration screening device to perform screening at a frequency of 2000 to 5000 times per minute.

[0042] The above-mentioned degradable lignin-based water-soluble polymer flocculant is selected from lignin, acrylamide monomer, and functional monomers, and is prepared by adding an initiator (used to initiate the polymerization reaction), a polymer dispersant (used to adjust the dispersibility of the reaction system to ensure the smooth progress of the reaction), and a cross-linking agent (used to enhance the cross-linking degree between polymer molecules and improve the stability of the product).

[0043] The functional monomers are selected from acrylic acid (AA), methyl methacrylate (MMA), N-vinyl pyrrolidone (NVP), etc.

[0044] The initiator can be selected from potassium persulfate, sodium bisulfite, etc.;

[0045] For the polymer dispersant, high molecular weight dispersants are selected, such as polyvinylpyrrolidone (PVP), sodium polyacrylate, etc.; surfactant-based dispersants: anionic (such as sodium dodecyl sulfate), cationic (such as cetyltrimethylammonium bromide), non-ionic (such as polyoxyethylene sorbitan monolaurate); inorganic salt dispersants: inorganic salts such as phosphates and silicates can be used as effective dispersants in some cases.

[0046] For the crosslinking agent, N,N'-methylenebisacrylamide (MBA), ethylene glycol dimethacrylate, etc. are selected.

[0047] The preparation method of the degradable lignin-based water-soluble polymer flocculant used in the examples of the present invention includes the following steps:

[0048] 1. Raw materials:

[0049] Lignin, acrylamide (AM), functional monomer, crosslinking agent, initiator and polymer dispersant.

[0050] 2. Ratio:

[0051] Lignin: accounting for 46% of the total mass of the lignin-based water-soluble polymer flocculant

[0052] Acrylamide (AM): accounting for 40% of the total mass of the lignin-based water-soluble polymer flocculant.

[0053] Functional monomer (acrylic acid AA): accounting for 10% of the total mass of the lignin-based water-soluble polymer flocculant.

[0054] Crosslinking agent (N,N'-methylenebisacrylamide MBA): accounting for 3% of the total mass of the lignin-based water-soluble polymer flocculant.

[0055] Initiator (sodium bisulfite): accounting for 0.5% of the total mass of the lignin-based water-soluble polymer flocculant.

[0056] Dispersant (polyvinylpyrrolidone PVP): accounting for 0.5% of the total mass of the lignin-based water-soluble polymer flocculant.

[0057] 3. Method steps:

[0058] Lignin purification: The enzymatic hydrolysis lignin is purified through steps such as dissolution, pH adjustment, filtration, and drying to remove impurities and improve its purity, and the purity shall not be lower than 90%.

[0059] First reaction: Under nitrogen protection or in an inert gas atmosphere, purified enzymatically hydrolyzed lignin and a solvent (such as water or an organic solvent) are added to a reaction kettle, and an initiator is added simultaneously. At an environmental temperature of 60°C - 90°C, the solution is stirred thoroughly at a stirring rate of 200 - 600 revolutions per minute to decompose the initiator to generate free radicals, thereby initiating the polymerization reaction between lignin and acrylamide monomers to form a preliminary lignin-acrylamide graft polymer.

[0060] Second reaction: After the first reaction is completed, a polymerization dispersant (to adjust the dispersibility of the reaction system and prevent particle aggregation) and a selected crosslinking agent (such as N,N'-methylenebisacrylamide to enhance the crosslinking degree between polymer molecules) are added to the reaction system to carry out the second-stage polymerization reaction, enabling these monomers to further react with the preliminarily formed graft polymer to form a lignin-based water-soluble polymer with multiple functional structural units.

[0061] Purification: The product obtained from the second reaction is purified. First, the polymer is precipitated from the solution by soaking, and then washed several times with water to remove impurities such as residual unreacted monomers, oligomers, and solvents. After that, the washed polymer is dried to remove moisture. The dried polymer is crushed and sieved to obtain a lignin-based water-soluble polymer product.

[0062] 4. Product Structure

[0063] The product exhibits the characteristics of high molecular weight (2000 - 3500 kD) and has a complex network structure or branched structure. Due to the complex chemical reactions and the interaction of various raw materials involved in the preparation process of the lignin-based water-soluble polymer flocculant, it is usually difficult to precisely control the molecular weight of its product structure.

[0064] Example 1

[0065] A method for preparing recycled aggregates from wet-processed sand and stone powder includes the following steps:

[0066] Step 1: The wet-processed sand and stone washing wastewater containing 10000 mg of stone powder is injected into the stone powder storage bin of the stone powder flocculation and precipitation device through the wet-processed sand and stone powder feeding device, and then 10 mg of a degradable lignin-based water-soluble polymer flocculant is added through a feeder for flocculation and precipitation. After complete precipitation, the upper clear water is drained through the clean water drain port.

[0067] Step 2: The ultrasonic stirring and flocculation device is turned on, and the stirring time of the device is set to 60 s and the ultrasonic stirring power is set to 1500 W to accelerate the agglomeration of the wet-processed sand and stone powder under the action of the degradable lignin-based water-soluble polymer flocculant.

[0068] Step 3: After the stone powder coagulates into a mass in water, sodium dodecyl sulfate (SDS) is added until its molar concentration in the solution is 0.024 mol / L; and a sodium silicate (Na2O·nSiO2) solution with a modulus of 1.2 and a solid content of 45%, and an ultrafine slag powder with a specific surface area of 600 m 2 / kg, an activity index of 130%, and a fineness D90 below 10 μm are mixed with water in a mass ratio of 3:0.5:8 to obtain the inorganic cementitious component of the stone powder. Stir continuously until the inorganic cementitious component of the stone powder is evenly adsorbed on the surface of the agglomerated stone powder particles; turn off the ultrasonic stirring and flocculation device, add a flocculant degradation component with the chemical formula NaOH to ensure its molar concentration in the solution is 3 mol / L, and form recycled aggregates with a certain strength;

[0069] Step 4: Filter out the wastewater outside the agglomerated aggregates through a vacuum adsorption and filtration device at a vacuum degree of 0.06 MPa. Turn on the electromagnetic wave energy directional excitation device, set the frequency of the device to 2450 MHz, the wavelength to 0.122 m, and the output power to 600 W to accelerate the evaporation of moisture inside the aggregates. At the same time, further promote the condensation and hardening of the recycled aggregates made from stone powder to meet the performance requirements; turn on the high-frequency vibration screening device, and screen the recycled aggregates into graded aggregates of 0.15 mm - 0.30 mm, 0.30 mm - 0.60 mm, 0.60 mm - 1.18 mm, 1.18 mm - 2.36 mm, 2.36 mm - 4.75 mm, 5 mm - 10 mm, and 10 mm - 20 mm, thus completing the preparation of recycled aggregates made from wet-processed machine-made sand stone powder.

[0070] The performance of the recycled aggregates made from wet-processed machine-made sand stone powder prepared is shown in Table 1.

[0071] Table 1 Performance of Recycled Aggregates Made from Wet-Processed Machine-Made Sand Stone Powder in Example 1

[0072]

[0073]

[0074] Example 2

[0075] A method for preparing recycled aggregates from wet-processed sand stone powder includes the following steps:

[0076] Step 1: Inject the washing wastewater of wet-processed machine-made sand into the stone powder storage bin of the stone powder flocculation and precipitation device through the wet-processed sand stone powder feeding device, then add a degradable lignin-based water-soluble polymer flocculant through the feeder for flocculation and precipitation. After complete precipitation, drain the upper clear water through the clean water drain port;

[0077] Step 2: Turn on the ultrasonic stirring and flocculation device, and set the stirring time of the device to 60 s and the ultrasonic stirring power to 1500 W to accelerate the agglomeration of wet-processed washed sand powder under the action of the degradable lignin-based water-soluble polymer flocculant;

[0078] Step 3: After the stone powder agglomerates in water, add sodium dodecyl sulfate (SDS) until its molar concentration in the solution is 0.052 mol / L; and a sodium silicate (Na2O·nSiO2) solution with a modulus of 1.2 and a solid content of 45%, and an ultra-fine slag powder with a specific surface area of 600 m 2 / kg, an activity index of 130%, and a fineness D90 below 10 μm. The inorganic cementitious component of the stone powder is prepared by mixing the ultra-fine slag powder and water in a mass ratio of 3:0.5:8, and continue to stir until the inorganic cementitious component of the stone powder is evenly adsorbed on the surface of the agglomerated stone powder particles; turn off the ultrasonic stirring and flocculation device, and add a flocculant degradation component with the chemical formula NaOH to ensure its molar concentration in the solution is 5 mol / L to form recycled aggregate with a certain strength;

[0079] Step 4: Filter out the wastewater outside the agglomerated aggregate through a vacuum adsorption and filtration device at a vacuum degree of 0.08 MPa. Turn on the electromagnetic wave energy directional excitation device, set the frequency of the device to 2450 MHz, the wavelength to 0.122 m, and the output power to 600 W to accelerate the evaporation of moisture inside the aggregate, and at the same time further promote the condensation and hardening of the recycled aggregate made of stone powder to meet the performance requirements; turn on the high-frequency vibration screening device, and screen the recycled aggregate into graded aggregates of 0.15 mm - 0.30 mm, 0.30 mm - 0.60 mm, 0.60 mm - 1.18 mm, 1.18 mm - 2.36 mm, 2.36 mm - 4.75 mm, 5 mm - 10 mm, and 10 mm - 20 mm, thus completing the preparation of the recycled aggregate made of wet-processed sand powder.

[0080] The performance of the recycled aggregate made of wet-processed sand powder prepared is shown in Table 2.

[0081] Table 2 Performance of the recycled aggregate made of wet-processed sand powder in Example 2

[0082]

[0083] Example 3

[0084] A method for preparing recycled aggregate from wet-processed sand powder, comprising the following steps:

[0085] Step 1: Inject the wet-processed sand washing wastewater into the stone powder storage bin of the stone powder flocculation and precipitation device through the wet-processed sand powder feeding device, then add a degradable lignin-based water-soluble polymer flocculant through the feeder for flocculation and precipitation, and drain the upper clear water through the clean water drain port after complete precipitation;

[0086] Step 2: Turn on the ultrasonic stirring and flocculation device, and set the stirring time of the device to 60 s and the ultrasonic stirring power to 1500 W to accelerate the agglomeration of wet-processed machine-washed sand powder under the action of the degradable lignin-based water-soluble polymer flocculant;

[0087] Step 3: After the stone powder agglomerates in water, add sodium dodecyl sulfate (SDS) until its molar concentration in the solution is 0.086 mol / L; and a sodium silicate (Na2O·nSiO2) solution with a modulus of 1.2 and a solid content of 45%, and an ultra-fine slag powder with a specific surface area of 600 m 2 / kg, an activity index of 130%, and a fineness D90 of less than 10 μm. The inorganic cementitious component of the stone powder is prepared by mixing the ultra-fine slag powder and water in a mass ratio of 3:0.5:8, and continue to stir until the inorganic cementitious component of the stone powder is evenly adsorbed on the surface of the agglomerated stone powder particles; turn off the ultrasonic stirring and flocculation device, and add a flocculant degradation component with the chemical formula of NaOH to ensure that its molar concentration in the solution is 5 mol / L to form recycled aggregates with a certain strength;

[0088] Step 4: Filter out the wastewater outside the agglomerated aggregates through a vacuum adsorption and filtration device at a vacuum degree of 0.08 MPa. Turn on the electromagnetic wave energy directional excitation device, set the frequency of the device to 2450 MHz, the wavelength to 0.122 m, and the output power to 900 W to accelerate the evaporation of moisture inside the aggregates, and at the same time further promote the condensation and hardening of the recycled aggregates made from stone powder to meet the performance requirements; turn on the high-frequency vibration screening device, and screen the recycled aggregates into graded aggregates of 0.15 mm - 0.30 mm, 0.30 mm - 0.60 mm, 0.60 mm - 1.18 mm, 1.18 mm - 2.36 mm, 2.36 mm - 4.75 mm, 5 mm - 10 mm, and 10 mm - 20 mm, thus completing the preparation of recycled aggregates from wet-processed machine-made sand powder.

[0089] The performance of the prepared recycled aggregates from wet-processed machine-made sand powder is shown in Table 3.

[0090] Table 3 Performance of Recycled Aggregates from Wet-Processed Machine-Made Sand Powder in Example 3

[0091] Item Soundness / % Crushing index / % Example 3 4.0% (Class I) 19.6% (Class I)

[0092] Comparative Example 1

[0093] When the flocculant degradation component is not added, the preparation of recycled aggregates from wet-processed sand powder includes the following steps:

[0094] Step 1: Inject the sand washing wastewater from the wet-process mechanism sand into the stone powder storage bin of the stone powder flocculation and precipitation device through the wet-process stone powder feeding device. Then, add a degradable lignin-based water-soluble polymer flocculant through the feeder for flocculation and precipitation. After complete precipitation, drain the upper clear water through the purified water drain outlet;

[0095] Step 2: Turn on the ultrasonic stirring flocculation device, set the stirring time of the device to 60 s and the ultrasonic stirring power to 1500 W to accelerate the aggregation of the wet-process mechanism sand washing stone powder under the action of the degradable lignin-based water-soluble polymer flocculant;

[0096] Step 3: After the stone powder aggregates in water, add a 3% sodium dodecyl sulfate (SDS) solution with a molar concentration of 0.086 mol / L, a sodium silicate (Na2O·nSiO2) solution with a modulus of 1.5 and a solid content of 40%, and an ultrafine slag powder with a specific surface area of 800 m 2 / kg, an activity index of 150%, and a fineness D90 below 10 μm, and water to prepare a stone powder inorganic cementing component according to a mass ratio of 5:1:10. Continue to stir until the stone powder inorganic cementing component is evenly adsorbed on the surface of the stone powder agglomerated particles; Turn on the electromagnetic wave energy directional excitation device to accelerate the movement rate of the diagenetic agent molecules inside the recycled aggregate to form a recycled aggregate with a certain strength;

[0097] Step 4: Filter out the wastewater outside the agglomerated aggregate through the vacuum adsorption and filtration device at a vacuum degree of 0.08 MPa. Turn on the electromagnetic wave energy directional excitation device, set the frequency of the device to 2450 MHz, the wavelength to 0.122 m, and the output power to 900 W to accelerate the evaporation of the moisture inside the aggregate, and at the same time further promote the condensation and hardening of the stone powder to prepare recycled aggregate, so that it meets the performance requirements; Turn on the high-frequency vibration screening device to screen the recycled aggregate into graded aggregates of 0.15 mm - 0.30 mm, 0.30 mm - 0.60 mm, 0.60 mm - 1.18 mm, 1.18 mm - 2.36 mm, 2.36 mm - 4.75 mm, 5 mm - 10 mm, and 10 mm - 20 mm, and complete the preparation of the recycled aggregate from the wet-process mechanism sand washing stone powder.

[0098] Table 4 Performance of Recycled Aggregate Prepared from Wet-Process Mechanism Sand Washing Stone Powder in Comparative Example 1

[0099] Item Soundness / % Crushing index / % Comparative Example 1 23.9% (failed to meet the standard) 52.3% (failed to meet the standard)

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing recycled aggregate by wet sand and stone powder production, characterized in that: The specific steps include: Step 1: adding a degradable lignin-based water-soluble flocculant to the stone powder slurry produced by wet sand making for flocculation and precipitation, and draining the upper clear water after the precipitation is complete; the degradable lignin-based water-soluble flocculant is selected from lignin, acrylamide monomer and functional monomer, and is prepared by adding an initiator, a polymer dispersant and a cross-linking agent; The functional monomer is selected from acrylic acid, methyl methacrylate or N-vinyl pyrrolidone; Step 2: using an ultrasonic stirring and flocculation device to perform ultrasonic stirring and flocculation on the stone powder obtained by wet sand making; Step 3: Adding a diagenetic agent for activating the activity of stone powder accounting for 5% to 10% of the total amount of stone powder to the flocculated stone powder to prepare a primary formed recycled aggregate; Step 4: filter the initially formed recycled aggregate from the diagenetic agent, use the electromagnetic wave energy directional excitation device again to accelerate the hardening of the aggregate, and obtain recycled aggregates of different particle sizes after screening; The stone powder activity-stimulated diagenetic agent comprises 5-10 parts by weight of a flocculant degradation component, 1-3 parts by weight of a surface active component and 15-20 parts by weight of a stone powder inorganic cementing component; The flocculant degradation component is a NaOH or KOH solution with a molar concentration of 2 mol / L to 5 mol / L; The surface active component is sodium dodecyl sulfate or octylphenol polyoxyethylene ether with a molar concentration of 0.01 mol / L to 0.1 mol / L; The stone powder inorganic cementing component is sodium silicate with a modulus of 1.0 to 1.5 and a specific surface area of ​​600m 2 / kg, activity index ≥120%, ultrafine slag powder with a fineness D90 below 10μm and water in a mass ratio of (3-5): (0.5-1): (8-10) to obtain a solution.

2. The method for preparing recycled aggregate by wet sand and stone powder production according to claim 1, characterized in that: The polymer dispersant is a high molecular weight dispersant, and the high molecular weight dispersant is polyvinyl pyrrolidone or sodium polyacrylate.

3. The method for preparing recycled aggregate by wet sand and stone powder production according to claim 1, characterized in that: In step 2, the stirring time of ultrasonic stirring flocculation is 30s-60s, and the ultrasonic stirring power is 1000W-1500W.

4. The method for preparing recycled aggregate by wet sand and stone powder production according to claim 1, characterized in that: The working parameters of the directional excitation of electromagnetic wave energy in step 4 are: frequency of 2450 MHz, wavelength of 0.122 m, output power of 600 W or 900 W; the screening uses a high-frequency vibration screening device to screen the hardened recycled aggregate into recycled aggregates of different particle sizes of 0.15 mm to 0.30 mm, 0.30 mm to 0.60 mm, 0.60 mm to 1.18 mm, 1.18 mm to 2.36 mm, 2.36 mm to 4.75 mm, 5.00 mm to 10.00 mm and 10.00 mm to 20.00 mm.

5. The method for preparing recycled aggregate by wet sand and stone powder production according to claim 1, characterized in that: The device for preparing recycled aggregate by wet sand and stone powder comprises: a stone powder flocculation and sedimentation device, an ultrasonic stirring flocculation device, a vacuum adsorption and filtration device, an electromagnetic wave energy directional excitation device and a high-frequency vibration screening device.

6. The method for preparing recycled aggregate by wet sand and stone powder production according to claim 5, characterized in that: The stone powder flocculation and precipitation device comprises: a degradable lignin-based water-soluble flocculant feeder (1), a stone powder storage bin (15), a wet sand making stone powder feeding device (2) and a clean water outlet (16); The ultrasonic stirring flocculation device comprises an ultrasonic vibrator (12), an ultrasonic vibration generator (7) and a control panel (6); The vacuum adsorption filtration device comprises a purification filter (14), a vacuum adsorption conduit (13), a vacuum dehydration storage device (10) and a high-power vacuum pump (11); The electromagnetic wave energy directional excitation device comprises an electromagnetic wave energy generator (4) and an electromagnetic wave energy directional transmission device (5).

7. The recycled aggregate prepared by the method according to any one of claims 1 to 6.

Images