Device and method for preparing sprayed concrete alkali-free liquid accelerator at normal temperature

Abstract

According to the device and method for preparing the sprayed concrete alkali-free liquid accelerator at the normal temperature, a stirring barrel cover of a stirring barrel of the device is communicated with a left side feeding hopper and a right side feeding hopper capable of conducting timed discharging, a discharging pipe is arranged at the bottom of the stirring barrel, and a valve is installed on the discharging pipe; a horizontally arranged stirring wheel disc is fixedly connected to the bottom of the stirring shaft in the stirring barrel, a plurality of vertically upward stirring upper blades are uniformly distributed and connected to the outer ring of the stirring wheel disc, a vertically downward stirring lower blade is arranged on the outer ring of the stirring wheel disc between every two stirring upper blades, and the periphery of the stirring wheel disc extends out and is connected with a scraping blade. During preparation, the proportioned liquid raw material of the liquid alkali-free accelerator is put into the left feed hopper and enters the stirring barrel, the powder raw material is put into the right feed hopper and then is pushed into the stirring barrel at regular time by several times for high-speed stirring, and the prepared liquid alkali-free accelerator accelerates the initial setting time of concrete and improves the compressive strength.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixture preparation, and in particular to a device and method for preparing an alkali-free liquid quick-setting agent for shotcrete at room temperature. Background Art

[0002] Liquid alkali-free quick-setting agent is an admixture used in shotcrete construction. It is mainly used in the construction and emergency repair of shotcrete projects such as railway tunnels, underground projects, mining projects, slope protection, etc. Its main function is to promote the early coagulation and hardening of shotcrete, thereby shortening the setting time of concrete and improving the early strength of concrete, so as to provide support force in time.

[0003] The conventional preparation method of the conventional liquid alkali-free quick-setting agent is to continuously add the component materials into the reactor in sequence and heat them to obtain the alkali-free liquid quick-setting agent. However, this conventional liquid alkali-free quick-setting agent preparation device has the following defects: the preparation process consumes a lot of energy, lacks certain automatic control, and requires a lot of manpower and time to add and mix the required materials. Secondly, in the process of preparing the liquid alkali-free quick-setting agent, the solution is easily affected by temperature. When the solution ends the heating and stirring state, the temperature will drop sharply, causing the liquid to crystallize, and the viscosity and fluidity will change. This undoubtedly has a certain impact on the production rate and product quality of the liquid alkali-free quick-setting agent. Therefore, people have developed a technology for preparing alkali-free liquid quick-setting agents at room temperature, such as: 1. Chinese Patent: A method for preparing an alkali-free liquid accelerator for fast-hardening and early-strength shotcrete at room temperature, application number: 202211332694.X, application date: 2022.10.25, abstract: The present invention discloses a method for preparing an alkali-free liquid accelerator for fast-hardening and early-strength shotcrete at room temperature, and the method for preparing an alkali-free liquid accelerator for fast-hardening and early-strength shotcrete at room temperature comprises the following steps: at room temperature, water, aluminum sulfate, active aluminate solution, modified aluminum hydroxide, fluosilicic acid, lithium sulfate, diethanolamine, triisopropanolamine, sorbitol, ultrafine aluminum silicate, magnesium aluminum silicate and Wenlun glue are mixed and stirred to prepare a concrete accelerator. The concrete accelerator prepared by the present invention has a fast setting time and high early strength, and no heating is required during the production process, and it can be carried out at room temperature, which greatly reduces production energy consumption and reduces process costs.

[0004] 2. Chinese Patent: An environmentally friendly alkali-free liquid accelerator and its preparation method at room temperature, application number: 201911366257.8, application date: 2019.12.26, abstract: The invention discloses an environmentally friendly alkali-free liquid accelerator and its preparation method at room temperature; the accelerator is mixed in mass fraction as follows: 45-60% aluminum sulfate, 5-10% alcohol amine, 0-2.5% complexing agent, 0.5-2% organic acid, and the rest is water; the method for preparing the accelerator at room temperature includes: weighing each component according to the mass ratio; mixing alcohol amine, complexing agent and water and stirring for a certain time to form liquid A; adding aluminum sulfate to liquid A and continuing to stir for a certain time to form liquid B; adding organic acid to liquid B and continuing to stir for a certain time to obtain an alkali-free liquid accelerator. The invention can prepare liquid accelerator at room temperature, uses fewer types of raw materials during preparation, does not need to use dripping equipment, and the configured accelerator has no harmful fluoride ions and chloride ions. The invention can effectively reduce production costs.

[0005] 3. Chinese patent: An alkali-free liquid accelerator and its preparation method at room temperature, application number: 201611239918.7, application date: 2016.12.29, abstract: The present invention relates to an alkali-free liquid accelerator used in shotcrete and its preparation method at room temperature. The alkali-free liquid accelerator of the present invention is prepared from the following components in weight ratio: 40-50 parts of aluminum sulfate, 6-8 parts of ferrous sulfate, 2-4 parts of sodium fluoride, 1-3 parts of diethanolamine, 1-2 parts of catalyst, 0.1-0.5 parts of polyacrylamide, and 45-55 parts of water. The present invention is widely used in the support, plugging, and repair of roads, railways, mines, and subways. The alkali-free liquid accelerator of the present invention has a simple production process, a reaction temperature of room temperature, an alkali-free light blue viscous liquid, high early strength, high late strength ratio, high cost performance, and low energy consumption and no pollution during the production, use, and transportation process.

[0006] 4. Chinese Patent: A production equipment for preparing liquid alkali-free quick-setting agent at room temperature, application number: 202022399358.X, application date: 2020.10.26, abstract: The utility model relates to the technical field of quick-setting agent, and more specifically, to a production equipment for preparing liquid alkali-free quick-setting agent at room temperature. It includes a tank body, a frame-type stirring anchor and a distribution pipe. The frame-type stirring anchor is arranged in the tank body, a first reduction motor is arranged on the top of the tank body, the output shaft of the first reduction motor is fixedly connected to the frame-type stirring anchor, an exhaust pipe and a feed pipe are arranged on the top of the tank body, the distribution pipe is fixedly connected to the top of the inner wall of the tank body through a connecting rod, a drip pipe is arranged at the bottom of the distribution pipe, and a circulation pipe is connected to the side wall of the distribution pipe. A base is arranged at the bottom of the tank body, and a four-leaf open turbine stirring anchor is connected to the base. The side wall of the base is connected to a discharge pipe, and the discharge pipe is connected to a delivery pump, which is connected to the circulation pipe through a pipeline tee. This equipment can circulate and stir the materials, reduce the generation of wall hanging, realize circulatory stirring, and effectively improve the mixing effect of the materials. The utility model is mainly used in the preparation of liquid alkali-free quick-setting agent.

[0007] 5. Chinese Patent: A production equipment for preparing alkali-free liquid accelerator at room temperature, application number: 202222593463.6, application date: 2022.09.28, abstract: The utility model relates to the technical field of mechanical production equipment, specifically a production equipment for preparing alkali-free liquid accelerator at room temperature, including a cylinder and a stirring device, the stirring device includes a high-speed stirring and dispersing device arranged at the top of the cylinder and a supplementary stirring device arranged at the bottom of the cylinder, the stirring device can stir in the inner cavity of the cylinder, the high-speed stirring and dispersing device can reach a maximum speed of (3500-4000) r / min, three dispersing shear disks are distributed on its rotating shaft, and shear teeth are alternately distributed up and down on the circumference of the dispersing shear disk, and shear blades are distributed in the radial direction of the disk at a certain angle to the horizontal plane, which can efficiently stir and disperse the material; at the same time, a scraper is provided on the side of the U-shaped stirring shaft of the supplementary stirring device close to the inner wall of the cylinder to prevent the material from sticking to the inner wall of the cylinder and make the stirring more sufficient.

[0008] Through applied research, it was found that the raw material ratio and preparation process of the alkali-free liquid accelerator in the above-mentioned document 1 are complicated, the dosage of document 2 needs to be increased to achieve the ideal initial setting time and compressive strength, the initial setting time of document 3 is relatively long, and the production equipment disclosed in documents 4 and 5 cannot achieve high-speed stirring and shearing due to the stirring blade structure used. Summary of the invention

[0009] The purpose of the present invention is to provide a device and method for preparing an alkali-free liquid accelerating setting agent for shotcrete at room temperature in view of the problems existing in the prior art. The technology adopts a normal temperature stirring device to prepare a powder material of a liquid alkali-free accelerating setting agent with a good ratio, and pushes the powder material into a stirring barrel in batches at a fixed time and adopts high-speed stirring. The prepared liquid alkali-free accelerating setting agent accelerates the initial setting time of concrete and improves the compressive strength.

[0010] The present invention is achieved by adopting the following technical solutions: A device for preparing alkali-free liquid quick-setting agent for shotcrete at room temperature comprises a mixing barrel, a mixing barrel cover is installed on the top of the mixing barrel, a left feed inlet and a right feed inlet are arranged on the mixing barrel cover, the left feed inlet and the right feed inlet are connected to a left feed hopper and a right feed hopper respectively through a left feed pipe and a right feed pipe, a mixing motor is installed at the middle position of the top of the mixing barrel cover, the mixing motor is vertically connected to a mixing shaft extending into the lower part of the mixing barrel, the upper end of the mixing shaft is rotatably connected to the mixing barrel cover through a bearing, and a mixing motor is installed at the bottom of the mixing barrel. A discharge pipe is provided with a valve, a horizontally arranged stirring wheel is fixedly connected to the bottom of the stirring shaft, a plurality of vertically upward stirring upper blades are evenly connected to the outer ring of the stirring wheel, a vertically downward stirring lower blade is arranged on the outer ring of the stirring wheel between every two stirring upper blades, a scraper is also extended out from the outer periphery of the stirring wheel and connected, in order to maintain balance, two scrapers are arranged symmetrically around the center of the stirring wheel, and one end of the scraper is fixed to the lower stirring blade; a timed discharger is installed in the right side feed hopper.

[0011] Further preferred: the timing feeder comprises a timing push rod, a support plate and a support bar, the support plate is installed in the right feed hopper through the support bar for horizontal support, one side of the support plate and the inner wall of the right feed hopper are reserved with a material drop hole, and the timing push rod is installed on the support plate away from the material drop hole. The end of the timing push rod is connected to a rectangular steel plate, and the timing push rod is controlled by programming and an external power supply to move forward at a regular time to push the material off the support plate.

[0012] Further preferably, the left side feed hopper and the right side feed hopper are supported and installed above the mixing barrel by a support frame.

[0013] Further preferably, a control switch for controlling the operation of the timing push rod and the stirring motor is installed on the outside of the lower end of the stirring barrel, and the control switch is connected to a power supply.

[0014] Further preferably, a base is provided at the bottom of the mixing barrel.

[0015] Further preferably, the upper stirring blade, the lower stirring blade and the scraper blade are all rectangular plates.

[0016] Further preferably, the stirring speed of the stirring shaft is 5000r / min-6000r / min.

[0017] Further preferred: the preparation process of the alkali-free liquid accelerating agent for shotcrete is: Step 1, raw material preparation: Take 50-52% polyaluminium sulfate, 3.5-4% aluminium hydroxide, 3.5-4% liquid nano CSH gel, 2.5-3% triethanolamine, 2.5-3% ethylenediaminetetraacetic acid, 5-7% magnesium sulfate, 0.5-1% polyacrylamide, and the rest is water. Polyaluminium sulfate is the main raw material for preparing the accelerator, mainly to increase the Al content in the solution. 3+ and SO4 2- The concentration of AFt is increased, and a large amount of calcium sulfonate (AFt) is generated in the cement paste, and a cross-linked network structure is formed, thereby promoting the setting and hardening of the paste and the development of compressive strength. The aluminum sulfate in the liquid accelerator directly reacts with aluminum hydroxide to produce polyaluminum sulfate, which maximizes the concentration of highly active aluminum ions in the liquid accelerator. The role of polyacrylamide in the accelerator is mainly reflected in the formation of coordination bonds between its amide group and the aluminum in aluminum sulfate, thereby maintaining the solubility of aluminum sulfate in the liquid accelerator. At the same time, the thickening effect of polyacrylamide can reduce the rebound rate of shotcrete and improve construction efficiency. In addition, polyacrylamide can also promote the shortening of setting time and the improvement of early compressive strength, thereby enhancing the early performance of concrete and improving the quality of the project. Nano-CSH gel can provide additional nucleation points for the formation of hydration product CSH gel, greatly reduce the barrier to the formation of CSH gel, promote the formation of hydration product CSH gel, and promote the further dissolution of mineral substances such as C3S and C2S in cement while producing CSH, thereby accelerating the early hydration of cement, promoting the formation of hydration products, thereby shortening its setting time and improving early strength. Secondly, the nano-gel structure of nano-CSH gel absorbs aluminum sulfate molecules in the stabilizing system, thus ensuring the stability of the liquid accelerator. Magnesium sulfate has a good reinforcing effect. 2+ Can be combined with OH - Combined with Mg(OH)2 crystals, which have a much greater crystallization ability than Ca(OH)2, they can provide nuclei, greatly reduce the nucleation barrier of hydration products, make hydration products easier to generate, and accelerate the Ca 2+ The dissolution rate is increased, and the hydration of C3S is promoted, thereby improving the early and late strength of cement. The nitrogen atom in the alcohol amine of triethanolamine is easy to form a public valence bond with the cation, complexing the aluminum ion of the accelerating component, increasing the concentration of aluminum ions participating in the reaction of the accelerator, and promoting the shortening of the setting time and the improvement of the early compressive strength. Ethylene diamine tetraacetic acid (EDTA) can inhibit the Al 3+ Water desorption can also be achieved by reacting with Al 3+The formation of chelates increases the solubility of aluminum sulfate, and secondly, the pH value can be adjusted, which can effectively alleviate the instability problem caused by the hydrolysis-polymerization-precipitation of aluminum ions.

[0018] Step 2: Feeding: Triethanolamine, liquid nano-CSH gel and water are fed from the left feed port and enter the mixing barrel through the left feed pipe; polyaluminum sulfate, aluminum hydroxide, ethylenediaminetetraacetic acid, polyacrylamide and magnesium sulfate are fed from the right feed port. Most of the raw materials are supported by the support plate, and a small part falls from the drop hole and enters the mixing barrel through the right feed pipe.

[0019] Step 3. Start stirring: Turn on the stirring motor and timing push rod through the control switch. The stirring speed of the stirring shaft is 5000r / min-6000r / min. The timing push rod is pushed once every 3-5 minutes, and the total pushing time is 1h-3h.

[0020] Step 4: Open the valve to discharge: After the mixing is completed, open the valve and the quick-setting agent in the tank will be discharged from the discharge pipe.

[0021] Compared with the prior art, the invention has the following beneficial effects: by adjusting the control switch, the stirring motor starts to run, the output shaft of the stirring motor drives the stirring shaft to start rotating, the stirring shaft drives the stirring wheel to rotate, thereby driving the stirring upper blade, the stirring lower blade, and the scraper to rotate, and the sprayed concrete alkali-free liquid accelerator can be highly stirred and prepared. By putting powder raw materials (aluminum sulfate, etc.) into the right feed hopper, and by setting the program, the timing push rod pushes the powder raw materials (aluminum sulfate, etc.) into the right feed pipe set at the lower end of the right feed hopper in batches, and enters the inside of the mixing barrel through the right feed port. Secondly, by putting liquid materials (triethanolamine) and water into the left feed hopper, and entering the inside of the mixing barrel through the left feed pipe and the left feed port set at the lower end of the left feed hopper. After the liquid alkali-free accelerator preparation material enters the inside of the mixing barrel, it is stirred at high speed without heat source for several hours to obtain the liquid alkali-free accelerator. Then, the outflow rate of the liquid alkali-free quick-setting agent is controlled by controlling the valve of the discharge pipe at the lower end of the mixing barrel. The liquid alkali-free quick-setting agent is prepared by the above-mentioned room temperature preparation device for liquid alkali-free quick-setting agent. Only the raw materials of the quick-setting agent need to be added and the valve of the discharge pipe needs to be controlled. The rest can be automated, which can greatly reduce the tediousness of the preparation process and the labor cost. Secondly, in the preparation process, it can also avoid the rapid drop in temperature during the preparation process when the quick-setting agent changes from a heated and stirred state to a normal temperature state, which has an adverse effect on the liquid alkali-free quick-setting agent product (crystallization precipitation, equipment blockage, etc.), thereby improving the production efficiency and product quality of the liquid alkali-free quick-setting agent for shotcrete. The prepared liquid alkali-free quick-setting agent can accelerate the initial setting time of concrete and improve the compressive strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the installation structure of a device for preparing liquid alkali-free quick-setting agent at room temperature; Figure 2 It is a partial cutaway schematic diagram of a mixing barrel; Figure 3 It is a schematic diagram of the structure of the right side feed hopper; The names corresponding to the numbers in the figure are: 1. Support frame; 2. Left feed hopper; 3. Right feed hopper; 4. Timing push rod; 5. Stirring motor; 6. Right feed pipe; 7. Right feed inlet; 8. Stirring barrel cover; 9. Stirring barrel; 10. Control switch; 11. Base; 12. Discharge pipe; 13. Valve; 14. Left feed inlet; 15. Left feed pipe; 16. Stirring shaft; 17. Stirring upper blade; 18. Stirring lower blade; 19. Stirring wheel; 20. Scraper; 21. Support plate; 22. Support bar. DETAILED DESCRIPTION

[0023] The technical solutions in the invention are clearly and completely described below in conjunction with the embodiments. The described embodiments are only a part of the present invention, rather than all the embodiments. Example 1

[0024] A device for preparing alkali-free liquid quick-setting agent for shotcrete at room temperature, comprising a mixing barrel 9, a mixing barrel cover 8 is installed on the top of the mixing barrel 9, a left feed port 14 and a right feed port 7 are arranged on the mixing barrel cover 8, the left feed port 14 and the right feed port 7 are connected to the left feed hopper 2 and the right feed hopper 3 through a left feed pipe 15 and a right feed pipe 6 respectively, a mixing motor 5 is installed at the middle position of the top of the mixing barrel cover 8, the mixing motor 5 is vertically connected to a mixing shaft 16 extending into the lower part of the mixing barrel 9, the upper end of the mixing shaft is rotatably connected to the mixing barrel cover 8 through a bearing, and a discharge pipe 12 is arranged at the bottom of the mixing barrel 9 A valve 13 is installed on the discharge pipe 12, and a horizontally arranged stirring wheel 19 is fixedly connected to the bottom of the stirring shaft 16. A plurality of vertically upward stirring upper blades 17 are evenly connected to the outer ring of the stirring wheel 19. A vertically downward stirring lower blade 18 is arranged on the outer ring of the stirring wheel 19 between every two stirring upper blades 17. A scraper 20 is also extended from the outer periphery of the stirring wheel 19. In order to maintain balance, two scrapers 20 are symmetrically arranged around the center of the stirring wheel 19, and one end of the scraper 20 is fixed to the lower stirring blade 18; a timed feeder is installed in the right side feed hopper 3.

[0025] The timing feeder comprises a timing push rod 4, a support plate 21 and a support bar 22. The support plate 21 is horizontally supported and installed in the right feed hopper 3 through the support bar 22. A material-dropping hole is reserved between one side of the support plate 21 and the inner wall of the right feed hopper 3. The timing push rod 4 is installed on the support plate 21 away from the material-dropping hole. A rectangular steel plate is connected to the end of the timing push rod. The timing push rod is controlled by programming and an external power supply to move forward at a regular time to push the material off the support plate 21.

[0026] The left side feed hopper 2 and the right side feed hopper 3 are supported and installed above the mixing barrel 9 through the support frame 1 .

[0027] A control switch 10 for controlling the operation of the timing push rod 4 and the stirring motor 5 is installed on the outside of the lower end of the stirring barrel 9, and the control switch 10 is connected to a power source.

[0028] The bottom of the mixing barrel 9 is provided with a supporting base 11 .

[0029] The upper stirring blade 17, the lower stirring blade 18 and the scraper blade 20 are all rectangular plates.

[0030] The following steps can be used to prepare the alkali-free liquid accelerating agent for shotcrete at room temperature: Step 1, raw material preparation: take 52% polyaluminium sulfate, 4% aluminium hydroxide, 4% liquid nano CSH gel, 3% triethanolamine, 3% ethylenediaminetetraacetic acid, 7% magnesium sulfate, 1% polyacrylamide, and the rest water according to mass percentage; Step 2, feeding: triethanolamine, liquid nano CSH gel and water are fed from the left feed port 14 and enter the mixing barrel through the left feed pipe; polyaluminium sulfate, aluminium hydroxide, ethylenediaminetetraacetic acid, polyacrylamide and magnesium sulfate are fed from the right feed port 7, most of the raw materials are supported by the support plate, and a small part falls from the drop hole and enters the mixing barrel through the right feed pipe; Step 3, start stirring: turn on the stirring motor and the timing push rod through the control switch, the stirring speed of the stirring shaft 16 is 5000r / min, the timing push rod is pushed once every 3-5min, and the total pushing time is 1h-3h; Step 4: Open the valve to discharge: After the mixing is completed, open the valve and the quick-setting agent in the tank will be discharged from the discharge pipe. Example 2

[0031] Preparation speed: 6000r / min; Raw materials: polyaluminium sulfate 52%, aluminium hydroxide 4%, liquid nano CSH gel 4%, triethanolamine 3%, ethylenediaminetetraacetic acid 3%, magnesium sulfate 7%, polyacrylamide 1%, water 26%.

[0032] Comparative Example 1 Preparation speed: 4000r / min; Raw materials: polyaluminium sulfate 52%, aluminium hydroxide 4%, liquid nano CSH gel 4%, triethanolamine 3%, ethylenediaminetetraacetic acid 3%, magnesium sulfate 7%, polyacrylamide 1%, water 26%.

[0033] Comparative Example 2 Preparation speed: 7000r / min; Raw materials: polyaluminium sulfate 52%, aluminium hydroxide 4%, liquid nano CSH gel 4%, triethanolamine 3%, ethylenediaminetetraacetic acid 3%, magnesium sulfate 7%, polyacrylamide 1%, water 26%.

[0034] Comparative Example 3 Preparation speed: 5000r / min; Raw materials: 45% polyaluminium sulfate, 3% aluminium hydroxide, 3% liquid nano CSH gel, 2% triethanolamine, 2% ethylenediaminetetraacetic acid, 4% magnesium sulfate, 0.4% polyacrylamide, and the rest is water.

[0035] Comparative Example 4 Preparation speed: 5000r / min; Raw materials: polyaluminium sulfate 55%, aluminium hydroxide 5%, liquid nano CSH gel 5%, triethanolamine 4%, ethylenediaminetetraacetic acid 4%, magnesium sulfate 8%, polyacrylamide 2%, and the rest is water 2%.

[0036] The dosage of the quick-setting agent prepared by the method is 5% of the amount of cement used; the above-mentioned Examples 1 and 2 and Comparative Examples 1-4 were subjected to performance tests in the benchmark cement at a dosage of 5%; the test results are shown in the following table.

[0037]

[0038] It can be seen from the above table that the mix ratio and stirring speed of the preparation of the accelerating agent have an impact on the setting time and compressive strength of the benchmark cement.

[0039] The above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A device for preparing an alkali-free liquid quick-setting agent for shotcrete at room temperature, comprising a mixing barrel (9), a mixing barrel cover (8) installed on the top of the mixing barrel (9), a left feed port (14) and a right feed port (7) provided on the mixing barrel cover (8), the left feed port (14) and the right feed port (7) being connected to a left feed hopper (2) and a right feed hopper (3) via a left feed pipe (15) and a right feed pipe (6) respectively, a mixing motor (5) being installed at the middle position of the top of the mixing barrel cover (8), the mixing motor (5) being vertically connected to a mixing shaft (16) extending into the lower part of the mixing barrel (9), a discharge pipe (12) being provided at the bottom of the mixing barrel (9), a valve (13) being installed on the discharge pipe (12), and characterized in that: The bottom of the stirring shaft (16) is fixedly connected to a horizontally arranged stirring wheel (19), and the outer ring of the stirring wheel (19) is evenly connected to a plurality of vertically upward stirring upper blades (17), and the outer ring of the stirring wheel (19) between every two stirring upper blades (17) is provided with a vertically downward stirring lower blade (18), and the outer periphery of the stirring wheel (19) is also extended with a scraper (20) connected; a timer feeder is installed in the right side feed hopper (3).

2. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1, characterized in that: The timing feeder comprises a timing push rod (4), a support plate (21) and a support bar (22); the support plate (21) is horizontally supported and installed in the right feed hopper (3) through the support bar (22); a feeding hole is reserved on one side of the support plate (21) and the inner wall of the right feed hopper (3); and the timing push rod (4) is installed on the support plate (21) away from the feeding hole.

3. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1, characterized in that: The left-side feed hopper (2) and the right-side feed hopper (3) are supported and installed above the mixing barrel (9) via a support frame (1).

4. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1, characterized in that: A control switch (10) for controlling the operation of the timing push rod (4) and the stirring motor (5) is installed on the outside of the lower end of the stirring barrel (9), and the control switch (10) is connected to a power source.

5. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1 or 4, characterized in that: The bottom of the mixing barrel (9) is provided with a supporting base (11).

6. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1, characterized in that: The upper stirring blade (17), the lower stirring blade (18) and the scraper blade (20) are all rectangular plates.

7. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1, characterized in that: The stirring speed of the stirring shaft (16) is 5000 r / min-6000 r / min.

8. The device for preparing alkali-free liquid accelerating agent for shotcrete at room temperature according to claim 1, characterized in that: The preparation process of the alkali-free liquid accelerating agent for shotcrete is as follows: Step 1, raw material preparation: take by mass percentage: polyaluminium sulfate 50-52%, aluminium hydroxide 3.5-4%, liquid nano CSH gel 3.5-4%, triethanolamine 2.5-3%, ethylenediaminetetraacetic acid 2.5-3%, magnesium sulfate 5-7%, polyacrylamide 0.5-1%, and the rest is water; Step 2: Feeding: feeding triethanolamine, liquid nano-CSH gel and water from the left feed port (14); feeding polyaluminium sulfate, aluminium hydroxide, ethylenediaminetetraacetic acid, polyacrylamide and magnesium sulfate from the right feed port (7); Step 3, start stirring: turn on the stirring motor and the timing push rod through the control switch, the stirring speed of the stirring shaft (16) is 5000r / min-6000r / min, the timing push rod is pushed once every 3-5min, and the total pushing time is 1h-3h; Step 4: Open the valve to discharge: After the mixing is completed, open the valve and the quick-setting agent in the tank will be discharged from the discharge pipe.

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