A commercial mixing station carbon-fixing admixture, and preparation method and application thereof

Abstract

The present invention discloses a commercial mixed station carbon-fixing admixture, and a preparation method and application thereof. The preparation process of the admixture is as follows: 1000-1200 parts by mass of commercial mixed waste slurry, 80-100 parts by mass of recycled concrete powder, 500-600 parts by mass of water, 100-120 parts by mass of crystal form regulator, 1000-1200 parts by mass of grinding medium, and 10-15 parts by mass of surfactant are added to a wet grinder, and a CO2 mixed gas is introduced after pre-grinding, and the gas velocity is controlled during the grinding process, and the grinding environment is at normal pressure. When the reaction termination condition is reached, the grinding is terminated to obtain a solid waste commercial mixed waste slurry carbon-fixing admixture. The carbon-fixing admixture is added to ready-mixed concrete to replace admixtures such as fly ash, mineral powder, and silica fume. The present invention realizes the high added value utilization of carbon dioxide and the green utilization of commercial mixed solid waste resources, and has a simple preparation process, low cost, and high activity index.

Description

Technical Field

[0001] The present invention belongs to the field of carbon dioxide sequestration and the technical field of industrial solid waste resource utilization, and specifically relates to a commercial mixing station carbon-fixing admixture, and a preparation method and application thereof. Background Art

[0002] At present, with the rapid development of the construction industry, concrete, as one of the most important raw materials in the construction industry, the production of ready-mixed concrete is also increasing. However, a large amount of ready-mixed concrete waste is generated in various links involved in concrete preparation and transportation, such as ready-mixed concrete mixing stations and concrete transport trucks, which also causes pollution problems to the environment caused by the production of ready-mixed concrete.

[0003] Commercial mixed waste slurry is often used to produce recycled concrete aggregates and make ordinary concrete bricks, but the actual utilization rate is not high. Some commercial mixed stations even directly bury the waste, which not only causes waste but also brings serious pollution to the environment. It is relatively rare to use commercial mixed waste slurry to prepare active admixtures. The methods of using commercial mixed waste slurry to prepare admixtures include: thermochemical excitation, chemical titration, etc. After being treated by these methods, it is added as an admixture to the preparation of ready-mixed concrete. However, there are problems such as high energy consumption, complicated process, low replacement rate, and low activity index.

[0004] For example, a method for preparing a composite active admixture for concrete as described in patent number CN201810463812.8, firstly, the metal nickel-iron particles contained in the nickel-iron slag are separated by magnetic separation, and the remaining nickel-iron slag is then subjected to light calcination activation roasting and mechanical grinding-chemical excitation to obtain a composite active admixture. Compared with the prior art, this invention has a wide source of raw materials for production and a high degree of realization of the technical route. However, the process is relatively complicated, the energy consumption is high, and more admixtures need to be added during the production process.

[0005] For example, a regenerated active admixture and its preparation method described in patent number CN201510549555.6, wherein the raw materials are composed of recycled concrete powder and recycled glass powder. In the regenerated active admixture prepared by the present invention, since the activity of the recycled concrete powder itself is low, while the activity of the glass is high, the two can be used together to improve the activity of the recycled concrete fine aggregate powder. However, the growth cycle is long, the activity index is far below 95%, and the replacement rate is low. Summary of the invention

[0006] In view of the above problems in the prior art, the main purpose of the present invention is to provide a commercial mixing station carbon fixation admixture, and a preparation method and application thereof. The preparation method uses commercial mixing waste slurry as raw material, cooperates with recycled concrete micropowder to utilize wet grinding, and efficiently seals the CO2 mixed gas captured by the cement plant purification process to prepare a commercial mixing station carbon fixation admixture.

[0007] The present invention utilizes the solid waste system in combination with the wet grinding process of this research group, and realizes the ultra-fineness of solid waste particles based on the mechanical force and fluidization of the wet grinding process, and evenly distributes the refined particles in the wet grinding tank to react rapidly with CO2, and under the action of the crystal form regulator, a large number of micro-nano metastable needle-shaped aragonite calcium carbonate and vaterite calcium carbonate seeds are produced. Based on the particularity of high-pressure treatment, the solubility and diffusion coefficient of CO2 in water are increased, and the interfacial resistance of the solution is reduced. The prepared commercial mixed waste slurry solid carbon admixture directly replaces fly ash, silica fume, mineral powder and other admixtures, realizing the green utilization of solid waste resources and the integrated green process of high-value utilization of carbon dioxide, alleviating the pressure of carbon emissions, and has application prospects in the actual production process of ready-mixed concrete.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a method for preparing a carbon-fixing admixture in a commercial mixing station, comprising the following steps:

[0010] Step 1: Add 1000-1200 parts by mass of commercial mixed waste slurry A, 80-100 parts by mass of recycled concrete powder, 500-600 parts by mass of water, 100-120 parts by mass of crystal form regulator, 1000-1200 parts by mass of grinding media, and 10-15 parts by mass of surfactant into a wet grinding tank for pre-grinding;

[0011] Step 2: After the formal grinding begins, introduce CO2 mixed gas into the grinding tank, maintain the grinding environment at normal pressure, cool down in a water bath during the grinding process, and keep the temperature fluctuating within the range of 35-40°C. By observing the gas velocity meter, when the reaction ends and the standard is reached, stop grinding and obtain the commercial mixing station solid carbon admixture.

[0012] Furthermore, in step one, the commercial mixed waste slurry A is obtained by washing the site with water, cleaning the mixer truck and the mixing tank, and then filtering through sand and gravel to obtain waste slurry, the median particle size of the waste slurry A is 20-50 μm, the solid content of the waste slurry A is ≥50%, and the pH is 10-13; the particle diameter of the recycled concrete micropowder is <50 μm.

[0013] Furthermore, in step 1, the pre-grinding speed of the wet grinder is set to 100-150 r / min, and the grinding medium is a composite of zirconium oxide, agate balls, and steel balls in a mass ratio of 2-3:1-2:1-2.

[0014] Furthermore, in step 1, the crystal form regulator is polyacrylamide, hexadecyltrimethylammonium bromide, and waste pulp-chitosan solution, which are compounded in a mass ratio of 1-2:1-2:8-10.

[0015] Furthermore, the treatment method of the waste pulp-chitosan solution is as follows: first, 100-120 parts by weight of crab shells and shrimp shells are pickled for 5-6 minutes, washed in running water for 2-3 minutes after pickling, vacuum dried for 5-8 minutes after washing, put into a crusher for treatment after drying, and then sieve through a 0.45mm sieve to obtain mixed shell powder, and the mixed shell powder is subjected to alkali boiling to remove protein with 150-180 parts by weight of commercial mixed waste pulp for 10-15 minutes, and the alkali boiling temperature is 80-85°C to obtain the product.

[0016] Furthermore, the surfactant is a composite of one or two of a quaternary ammonium salt and a polycarboxylic acid water reducer. Preferably, the surfactant is a composite of a polycarboxylic acid water reducer (SUBOT-concrete high-efficiency water reducer) and a quaternary ammonium salt surfactant (alkyl trimethyl ammonium salt type).

[0017] Furthermore, in step 2, the rotation speed during the formal grinding process is 400-500 r / min.

[0018] Furthermore, in step 2, the median particle size of the solid carbon admixture of the commercial mixing station is 2-6 μm, the solid content is ≥50%, the slurry activity index is >100%, and the pH is 7-8.

[0019] Furthermore, in step 2, the CO2 mixed gas is concentrated flue gas captured by a cement plant, the CO2 purity in the flue gas is greater than 50%, the CO2 mixed gas is introduced at a gas rate of 10-12 parts by mass / min, and the grinding environment pressure is maintained at 13-15Mpa.

[0020] Furthermore, in step 2, the reaction end criterion is that the air velocity at the air inlet is equal to the air velocity at the air outlet and is maintained for more than 1 minute, which is the reaction end criterion.

[0021] In a second aspect, the present invention provides a commercial mixing station carbon-fixing admixture, which is prepared by the method described in the first aspect.

[0022] In a third aspect, the present invention provides the use of the commercial mixing station carbon-fixing admixture described in the second aspect as an admixture in the preparation process of ready-mixed concrete.

[0023] Furthermore, the admixture is used to replace fly ash, mineral powder and other admixtures, and the replacement amount is 90-100wt%.

[0024] The mechanism of the present invention is as follows:

[0025] Commercial mixed waste slurry is rich in calcium-based substances, the calcium ions in which can react with the carbonation reaction of CO3 in the solution. 2- Combined with the addition of a crystal modifier in the grinding environment, the Ca 2+ With CO3 2-The combination of metastable aragonite and vaterite calcium carbonate seeds is achieved by using the intense mechanical force generated by the wet grinding process to achieve ultra-fine particles of waste slurry and recycled concrete powder, promote Ca 2+ The solubility and diffusion coefficient of CO2 in the grinding solution are significantly improved under high pressure, which reduces the interfacial resistance of the solution and allows CO2 to quickly react with Ca after the carbonation process. 2+ The metastable aragonite and vaterite calcium carbonate are produced by combining and inhibiting the transformation of metastable calcium carbonate to stable calcite calcium carbonate under the action of crystal form regulator. Metastable aragonite and vaterite calcium carbonate have the characteristics of thermodynamic instability and can be used as a gel to promote the aggregation of cement particles and accelerate the hydration process of cement particles.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention provides a method for preparing a commercial mixing station carbon-fixing admixture, which uses commercial mixing waste slurry as a raw material for a mineral carbonization reaction. The integrated solid-waste carbon fixation is beneficial to alleviating a series of pollution problems caused by commercial mixing station waste slurry and greenhouse gas CO2, and realizes the green utilization of industrial waste and waste gas.

[0028] (2) The present invention provides a method for preparing a carbon-fixing admixture for a commercial mixing station, which utilizes a wet grinding process combined with a high-pressure grinding environment to achieve ultrafine calcium-based particles and promote the dissolution of calcium ions. At the same time, the calcium-based particles are evenly distributed in the solution, and CO2 is rapidly dissolved and diffused in the grinding solution, ultimately generating a large number of metastable aragonite and vaterite calcium carbonate seeds, thereby improving the activity of the admixture.

[0029] (3) The present invention provides an application method of a commercial mixing station carbon-fixing admixture, which can reduce the pH value of waste slurry to neutral. The commercial mixing station carbon-fixing admixture replaces 90%-100% of fly ash, silica fume, mineral powder and other external admixtures and is added to the preparation of ready-mixed concrete in the commercial mixing station, thereby improving the working performance and strength of concrete and greatly exerting the potential value of commercial mixing waste slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention provides a flow chart for the preparation and application of the commercial mixing station carbon-fixing admixture. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0034] In the following examples, unless otherwise specified, parts are parts by mass and replacement ratios are replacement ratios of other commercially available admixtures by mass.

[0035] In the following embodiments, commercial mixed waste slurry A is obtained by washing the site with water, cleaning the mixer truck and the mixing tank, and then filtering through sand and gravel to obtain waste slurry. The median particle size of the waste slurry A is 20-50 μm, the solid content of the waste slurry A is ≥50%, and the pH is 10-13; the particle diameter of the recycled concrete micropowder is <50 μm.

[0036] In the following embodiments, the recycled concrete powder comes from demolished buildings. The waste concrete is crushed and ground to obtain the recycled concrete powder, which mainly contains SiO2, CSH and CaCO3.

[0037] The raw materials involved in Examples 1-6 of the present invention, their mass fractions, and the replacement rates of admixtures such as fly ash and silica fume are shown in Table 1 below:

[0038] Table 1 Example ratio and parameter table

[0039]

[0040] Example 1

[0041] Step 1: Add 1000 parts by mass of commercial mixed waste slurry A, 100 parts by mass of recycled concrete powder, 600 parts by mass of water, 100 parts by mass of crystal form regulator, 1000 parts by mass of grinding media, and 10 parts by mass of surfactant into a wet grinding tank and pre-grind for 2 minutes;

[0042] Step 2: After the formal grinding begins, a CO2 mixed gas is introduced into the grinding tank, the grinding speed is 400r / min, the mixed gas introduction rate is 10 parts by mass / min, the grinding environment pressure is maintained at normal pressure, a water bath is used for cooling during wet grinding, and the temperature is kept within the range of 35-40°C. By observing the gas velocity meter, the reaction is stopped to obtain slurry B when the reaction end standard is reached, and the median particle size of slurry B is 6μm;

[0043] Step 3: Use slurry B as an admixture to replace 90% of silica fume in the preparation process of ready-mixed concrete.

[0044] In step 1, the crystal form regulator is polyacrylamide, hexadecyltrimethylammonium bromide, and waste pulp-chitosan solution, which are compounded in a mass ratio of 1-2:1-2:8-10. The treatment method of the waste pulp-chitosan solution is as follows: first, 100-120 parts by mass of crab shells and shrimp shells are pickled for 5-6 minutes, washed in running water for 2-3 minutes after pickling, vacuum dried for 5-8 minutes after washing, and placed in a crusher for treatment after drying, and then sieved through a 0.45mm sieve to obtain mixed shell micropowders, and the mixed shell micropowders are alkali boiled and protein-removed with 150-180 parts by mass of commercial mixed waste pulp for 10-15 minutes, and the alkali boiling temperature is 80-85°C, and the crystal form regulators in Examples 2-6 are the same as those in Example 1.

[0045] In step 1, the grinding medium is a composite of zirconium oxide, agate balls, and steel balls in a mass ratio of 2-3:1-2:1-2. The grinding media in Examples 2-6 are the same as in Example 1.

[0046] In step 1, the surfactant is a composite of a polycarboxylate water reducer (SUBOT-concrete high-efficiency water reducer) and a quaternary ammonium salt surfactant (alkyl trimethyl ammonium salt type). The surfactant in Examples 2-6 is the same as that in Example 1.

[0047] In step 2, the CO2 mixed gas is concentrated flue gas captured from a cement plant, and the CO2 purity in the flue gas is greater than 50%.

[0048] The CO2 mixed gas in Examples 2-6 is the same as that in Example 1.

[0049] Example 2

[0050] Step 1: Add 1000 parts by mass of commercial mixed waste slurry A, 80 parts by mass of recycled concrete powder, 600 parts by mass of water, 120 parts by mass of crystal form regulator, 1200 parts by mass of grinding media, and 15 parts by mass of surfactant into a wet grinding tank and pre-grind for 2 minutes;

[0051] Step 2: After the formal grinding begins, a CO2 mixed gas is introduced into the grinding tank, the grinding speed is 400r / min, the mixed gas introduction rate is 12 parts by mass / min, the grinding environment pressure is maintained at normal pressure, a water bath is used for cooling during wet grinding, and the temperature is kept within the range of 35-40°C. By observing the gas velocity meter, the reaction is stopped to obtain slurry B when the reaction end standard is reached, and the median particle size of slurry B is 6μm;

[0052] Step 3: In the preparation process of ready-mixed concrete, slurry B is used as an admixture to replace 100% of fly ash, silica fume and other external admixtures.

[0053] Example 3

[0054] Step 1: Add 1200 parts by mass of commercial mixed waste slurry A, 100 parts by mass of recycled concrete powder, 500 parts by mass of water, 120 parts by mass of crystal form regulator, 1200 parts by mass of grinding media, and 14 parts by mass of surfactant into a wet grinding tank and pre-grind for 2 minutes;

[0055] Step 2: After the formal grinding begins, a CO2 mixed gas is introduced into the grinding tank, the grinding speed is 500r / min, the mixed gas introduction rate is 11 parts by mass / min, the grinding environment pressure is maintained at normal pressure, a water bath is used for cooling during wet grinding, and the temperature is kept within the range of 35-40°C. By observing the gas velocity meter, the reaction is stopped to obtain slurry B when the reaction end standard is reached, and the median particle size of slurry B is 2μm;

[0056] Step 3: Use slurry B as an admixture to replace 100% of silica fume in the preparation of ready-mixed concrete.

[0057] Example 4

[0058] Step 1: Add 1200 parts by mass of commercial mixed waste slurry A, 90 parts by mass of recycled concrete powder, 550 parts by mass of water, 115 parts by mass of crystal form regulator, 1100 parts by mass of grinding media, and 12 parts by mass of surfactant into a wet grinding tank and pre-grind for 2 minutes;

[0059] Step 2: After the formal grinding begins, a CO2 mixed gas is introduced into the grinding tank, the grinding speed is 450r / min, the mixed gas introduction rate is 10 parts by mass / min, the grinding environment pressure is maintained at normal pressure, a water bath is used for cooling during wet grinding, and the temperature is kept within the range of 35-40°C. By observing the gas velocity meter, the reaction is stopped to obtain slurry B when the reaction end standard is reached, and the median particle size of slurry B is 4μm;

[0060] Step 3: Use slurry B as an admixture to replace 95% of silica fume in the preparation process of ready-mixed concrete.

[0061] Example 5

[0062] Step 1: Add 1100 parts by mass of commercial mixed waste slurry A, 85 parts by mass of recycled concrete powder, 580 parts by mass of water, 110 parts by mass of crystal form regulator, 1150 parts by mass of grinding media, and 13 parts by mass of surfactant into a wet grinding tank and pre-grind for 2 minutes;

[0063] Step 2: After the formal grinding begins, a CO2 mixed gas is introduced into the grinding tank, the grinding speed is 420r / min, the mixed gas introduction rate is 12 parts by mass / min, the grinding environment pressure is maintained at normal pressure, a water bath is used for cooling during wet grinding, and the temperature is kept within the range of 35-40°C. By observing the gas velocity meter, the reaction is stopped to obtain slurry B when the reaction end standard is reached, and the median particle size of slurry B is 5μm;

[0064] Step 3: Use slurry B as an admixture to replace 98% of silica fume in the preparation process of ready-mixed concrete.

[0065] Example 6

[0066] Step 1: Add 1150 parts by mass of commercial mixed waste slurry A, 95 parts by mass of recycled concrete powder, 540 parts by mass of water, 105 parts by mass of crystal form regulator, 1200 parts by mass of grinding media, and 11 parts by mass of surfactant into a wet grinding tank and pre-grind for 2 minutes;

[0067] Step 2: After the formal grinding begins, a CO2 mixed gas is introduced into the grinding tank, the grinding speed is 480r / min, the mixed gas introduction rate is 12 parts by mass / min, the grinding environment pressure is maintained at normal pressure, a water bath is used for cooling during wet grinding, and the temperature is kept within the range of 35-40°C. By observing the gas velocity meter, the reaction ends when the reaction standard is reached, and the reaction is stopped to obtain slurry B, the median particle size of slurry B is 3μm;

[0068] Step 3: Use slurry B as an admixture to replace 95% of fly ash in the preparation process of ready-mixed concrete.

[0069] Comparative Example 1

[0070] Only fly ash is taken as admixture.

[0071] Comparative Example 2

[0072] Only silica fume is taken as admixture.

[0073] The admixtures in Examples 1-6 and Comparative Examples 1-2 were used to prepare concrete in the following proportions:

[0074] Table 2 Concrete preparation ratios of examples and comparative examples

[0075]

[0076] The test results are as follows:

[0077] Table 3 Test results of embodiments and comparative examples

[0078]

[0079] As can be seen from Table 2, the carbon-fixing admixture prepared by the present invention can obtain a good slump when used to completely replace silica fume, and can obtain a similar slump when used to replace fly ash, which helps to improve the working performance of concrete. The carbon-fixing admixture is used to replace fly ash, silica fume and other admixtures in different proportions to obtain an increase in the 7d and 28d compressive strengths, the 3d compressive strength of the concrete is increased by 2-7%, the 28d compressive strength of the concrete is increased by 5-12%, and the activity index of 7d and 28d is greater than 100%. Using the carbon-fixing admixture of the present invention to replace cement helps to improve the later strength of concrete.

[0080] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a carbon-fixing admixture in a commercial mixing station, characterized in that: The following steps are involved: Step 1: Add 1000-1200 parts by mass of commercial mixed waste slurry A, 80-100 parts by mass of recycled concrete powder, 500-600 parts by mass of water, 100-120 parts by mass of crystal form regulator, 1000-1200 parts by mass of grinding media, and 10-15 parts by mass of surfactant into a wet grinding tank for pre-grinding; the surfactant is a quaternary ammonium salt, a polycarboxylic acid water reducer, or a combination of the two; In step 1, the crystal form regulator is polyacrylamide, hexadecyltrimethylammonium bromide, and waste pulp-chitosan solution, which are compounded in a mass ratio of 1-2:1-2:8-10; the treatment method of the waste pulp-chitosan solution is as follows: first, 100-120 parts by mass of crab shells and shrimp shells are pickled, washed in running water after pickling, vacuum dried after washing, put into a crusher after drying, and then sieved to obtain mixed shell micropowder, and the mixed shell micropowder is subjected to alkali boiling to remove protein with 150-180 parts by mass of commercial mixed waste pulp A for 10-15 minutes, and the alkali boiling temperature is 80-85°C, so as to obtain; Step 2: After the formal grinding begins, the CO2 mixed gas is introduced into the grinding tank, and the grinding environment is maintained at normal pressure. During the grinding process, a water bath is used to cool down the temperature and the temperature is kept within the range of 35-40 °C. By observing the gas velocity meter, the reaction end standard is reached and the grinding is stopped to obtain the commercial mixing station solid carbon admixture; In step 2, the median particle size of the carbon-fixing admixture of the commercial mixing station is 2-6 μm, the solid content is ≥50%, the slurry activity index is >100%, and the pH is 7-8; in step 2, the CO2 mixed gas is the concentrated flue gas captured by the cement plant, the CO2 purity in the flue gas is greater than 50%, and the CO2 mixed gas introduction rate is 10-12 parts by mass / min.

2. The preparation method according to claim 1, characterized in that: In step one, the commercial mixed waste slurry A is obtained by washing the site with water, cleaning the mixer truck and the mixing tank, and then filtering through sand and gravel. The median particle size of the commercial mixed waste slurry A is 20-50μm, the solid content of the waste slurry A is ≥50%, and the pH is 10-13; the particle diameter of the recycled concrete micropowder is <50μm.

3. The preparation method according to claim 1, characterized in that: In step 1, the pre-grinding speed of the wet grinder is set to 100-150 r / min, and the grinding medium is a composite of zirconium oxide, agate balls, and steel balls in a mass ratio of 2-3:1-2:1-2.

4. The preparation method according to claim 1, characterized in that: In step 2, the rotation speed during the formal grinding process is 400-500 r / min.

5. The preparation method according to claim 1, characterized in that: In step 2, the reaction end standard is that the air velocity at the air inlet is equal to the air velocity at the air outlet and is maintained for more than 1 minute, which is the reaction end standard.

6. A commercial mixing station carbon-fixing admixture, characterized in that: The method is prepared by any one of claims 1 to 5.

7. Use of the commercial mixing station carbon-fixing admixture according to claim 6 as an admixture in the preparation process of ready-mixed concrete.

Images