CN115108763A - Carbonated coal gangue-based paste and preparation method and application thereof - Google Patents
Carbonated coal gangue-based paste and preparation method and application thereof Download PDFInfo
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- CN115108763A CN115108763A CN202210645926.0A CN202210645926A CN115108763A CN 115108763 A CN115108763 A CN 115108763A CN 202210645926 A CN202210645926 A CN 202210645926A CN 115108763 A CN115108763 A CN 115108763A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/08—Acids or salts thereof
- C04B22/10—Acids or salts thereof containing carbon in the anion
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F15/00—Methods or devices for placing filling-up materials in underground workings
- E21F15/005—Methods or devices for placing filling-up materials in underground workings characterised by the kind or composition of the backfilling material
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00724—Uses not provided for elsewhere in C04B2111/00 in mining operations, e.g. for backfilling; in making tunnels or galleries
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/27—Water resistance, i.e. waterproof or water-repellent materials
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention relates to the field of backfill materials, and discloses a carbonated coal gangue-based paste as well as a preparation method and application thereof, wherein the method comprises the following steps: (1) introducing first CO into slurry obtained by mixing alkaline industrial solid waste and water 2 Performing primary carbonation reaction on the gas, separating out precipitate and drying to obtain a gelling dispersant; (2) mixing coal gangue, cement, an auxiliary cementing material, the cementing dispersant and water to obtain a coal gangue-based paste; (3) under the stirring state, introducing second CO into the coal gangue-based paste 2 Gas, performing secondary carbonation reaction, sealing, and formingAnd curing to obtain the carbonated gangue-based paste. The finished paste prepared by the method disclosed by the invention has good quality, can be used for filling and treating the coal mine goaf, has good tolerance in an underground humid environment, can effectively avoid the corrosion of the paste caused by the underground humid environment so as to ensure the strength, and simultaneously inhibits the pollution of the leaching of heavy metal ions in solid waste to an underground water circulating system.
Description
Technical Field
The invention relates to the field of backfill materials, in particular to a carbonated coal gangue-based paste and a preparation method and application thereof.
Background
At present, the total carbon dioxide emission amount in China exceeds 113 hundred million tons, and accounts for about 30 percent of the whole world; wherein CO emitted from the coal 2 Accounting for 45 percent of the total discharge of China, and about 50 hundred million tons. In the future, CO in the electric power industry of China 2 Emissions will remain on the scale of about 40t/a for long and medium periods of time, and therefore carbon dioxide capture, utilization and sequestration (CCUS) technology is an indispensable technology option for reducing carbon emissions.
The high-intensity industrial activities of China generate a large amount of solid wastes (comprising fly ash, steel slag, carbide slag and the like) every year, wherein the alkaline solid wastes are CO which has a very promising prospect 2 The raw materials are mineralized, and great potential is provided for carbon dioxide neutralization. The carbon fixation potential of solid wastes generated in each industrial activity in China each year exceeds 1 million tons, wherein the fly ash can absorb 8066 million tons of carbon dioxide each year, the steel slag can absorb 4200 million tons of carbon dioxide each year, and the carbide slag can absorb 892 million tons of carbon dioxide each year. Meanwhile, the inert solid waste (such as coal gangue) has certain mechanical strength and can be used as aggregate for building materials or used for backfilling mines or goafs.
Most of the existing coal mine goaf filling treatment establishes a filling system by using waste rocks stripped in the open air in the ground surface, mining waste rocks or mineral dressing tailings as main filling aggregates, but has the defects of high construction difficulty, high cost, poor operation safety and the like, and simultaneously produces excessive mining on natural resources. Therefore, the high-performance backfill paste material developed by utilizing the coal gangue is safer and more reliable.
CN111253139A discloses a method for preparing a high-performance structural material based on carbonation, which uses ground clinker, fine aggregate and an additive as raw materials, but CO thereof 2 The mineralization treatment is carried out after the material is poured and molded for 24 hours, the carbonation takes 5 to 36 hours, and in the reaction process, the reaction time is required to be multiplied by CO 2 The partial pressure is more than 2.5 MPa.h.
CN113443884A discloses a preparation method of a paste filling material, slurry and a filling body for a goaf, which is prepared by mixing coal gangue, fly ash, cement, desulfurized gypsum and stone powder with water, wherein the strength of the filling body prepared after standing for 18-25h in a mould is 4-5MPa, and the filling body is suitable for filling but not suitable for supporting.
The carbonation treatment method only aims at the prefabricated material and needs longer time and higher partial pressure of carbon dioxide for treatment; no CO is found in the related patents of the filler used in the goaf of the coal mine 2 Mineralization is used for preparing goaf backfill paste materials.
Disclosure of Invention
The invention aims to overcome the problem of poor tolerance of a paste filling material in a humid environment in the prior art, and provides a preparation method of a carbonated coal gangue-based paste, the carbonated coal gangue-based paste and application of the carbonated coal gangue-based paste.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a carbonated gangue-based paste, wherein the method comprises:
(1) introducing first CO into slurry obtained by mixing alkaline industrial solid waste and water 2 Performing primary carbonation reaction on the gas, separating out precipitate and drying to obtain a gelling dispersant;
(2) mixing coal gangue, cement, an auxiliary cementing material, the cementing dispersant and water to obtain a coal gangue-based paste;
(3) under the stirring state, introducing second CO into the coal gangue-based paste 2 And performing secondary carbonation reaction, sealing and forming, and naturally curing to obtain the carbonated coal gangue base paste.
In a second aspect of the invention, a carbonated gangue-based paste is provided, wherein the carbonated gangue-based paste is obtained by the method of the first aspect.
The third aspect of the invention provides the application of the carbonated gangue-based paste of the second aspect in underground backfilling of a coal mine goaf.
Through the technical scheme, the preparation method of the carbonated coal gangue based paste provided by the invention has the beneficial effects that:
(1) the finished paste has good quality, can be used for filling treatment of a coal mine goaf, has good tolerance in an underground humid environment, can effectively avoid the paste from being corroded in the underground humid environment so as to ensure the strength, and simultaneously inhibits the pollution of heavy metal ions in solid waste on an underground water circulating system due to leaching;
(2) the invention utilizes the industrial solid wastes such as coal gangue and the like from the coal power industry to realize low-cost resource utilization and the multi-stage step-by-step CO convenient to control 2 Mineralized and strengthened paste CO 2 Fixing to realize the performance enhancement of the paste;
(3) the preparation method is simple, the equipment investment and operation cost is low, the production energy consumption is low, and the solid waste and CO can be realized to a certain extent 2 Is an environment-friendly preparation process by synergistic utilization.
Drawings
FIG. 1 is a schematic flow diagram of the preparation of a carbonated gangue-based paste provided by the present invention;
FIG. 2 is a bar graph showing the carbon fixation rate of cement components of the pastes obtained in examples 1 to 3 of the present invention and comparative examples 1 to 2;
FIG. 3 is a bar graph showing uniaxial compressive strength before and after soaking of the pastes obtained in examples 1 to 3 of the present invention and comparative examples 1 to 2;
FIG. 4 is a Cu value of the paste obtained in example 4 of the present invention and comparative examples 3 to 4 after soaking in deionized water for 14 days 2+ Ion leaching concentrateBar graph of degree.
Description of the reference numerals
1. A first-stage carbonating reactor 2, a paste mixer 3 and a second-stage carbonating reactor
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a preparation method of a carbonated gangue-based paste, wherein the method comprises the following steps:
(1) introducing first CO into slurry obtained by mixing alkaline industrial solid waste and water 2 Performing primary carbonation reaction on the gas, separating out precipitate and drying to obtain a gelling dispersant;
(2) mixing coal gangue, cement, an auxiliary cementing material, the cementing dispersant and water to obtain a coal gangue-based paste;
(3) under the stirring state, introducing second CO into the coal gangue-based paste 2 And performing secondary carbonation reaction, sealing and forming, and naturally curing to obtain the carbonated coal gangue base paste.
In the present invention, fig. 1 is a schematic diagram of the preparation process of the carbonated coal gangue-based paste provided by the present invention, and as can be seen from fig. 1, the alkaline industrial solid waste and water are mixed and then sent into a primary carbonation reactor 1, and a first CO is introduced 2 Performing primary carbonation reaction on the gas to obtain the gelling dispersant, mixing the coal gangue, the cement, the auxiliary gelling material, the gelling dispersant and the water in a paste mixer 2 to obtain a coal gangue-based paste, sending the paste into a secondary carbonation reactor 3, and introducing second CO 2 And performing secondary carbonation reaction on the gas to obtain the carbonated coal gangue base paste.
In a preferred embodiment of the present invention, wherein in step (1), the alkaline industrial solid waste is at least one selected from carbide slag, steel slag, desulfurized slag and blast furnace slag.
In the present invention, in order to ensure the reactivity of the solid waste particles in the primary carbonation process, it is preferable that the particle size of the alkaline industrial solid waste is 100-500 μm in step (1).
In a preferred embodiment of the present invention, wherein in the step (1), the mass ratio of the alkaline industrial solid waste to water is 1: 5-15.
In the present invention, in order to ensure the efficiency of the carbonation reaction of the slurry so that a high conversion rate is achieved within a prescribed time, in step (1), the slurry has a pH of not less than 12.
In a preferred embodiment of the present invention, wherein, in step (1), the time of the primary carbonation reaction is 20 to 30 min.
In the present invention, the alkaline industrial solid waste and first CO 2 CO in gas 2 The mass ratio of the organic silicon compound is determined according to the conversion rate and the alkalinity of industrial solid wastes; preferably, the alkaline industrial solid waste and first CO 2 CO in gas 2 The mass ratio of (1): 0.5-2.
In a preferred embodiment of the present invention, wherein, in the step (1), the first CO 2 In the gas, CO 2 The volume concentration of (A) is 10-30%; introducing CO 2 The volume concentration is limited within the range, so that the gel dispersing agent prepared in the step (1) can play a good role in carbonation gel nucleation and dispersion, and is beneficial to strengthening secondary carbonation and improving the performance of the paste.
In a preferred embodiment of the present invention, wherein, in the step (1), the first CO 2 CO in gas 2 The volume flow rate of (2) is 100-500 mL/min.
In the invention, the granularity of the gelled dispersant obviously influences the dispersion performance of the gelled dispersant in the process of secondary carbonation reaction, and the dispersant with the specific embodiment that the fine granularity can help to optimize the pore structure, thereby strengthening CO 2 Mass transfer in paste system to improve paste qualityThe carbon fixation rate of the body; therefore, in order to effectively exert the function of the gel dispersant, sufficient gel dispersing ability is provided to promote the efficient progress of the secondary carbonation reaction, and preferably, the particle size of the gel dispersant is less than or equal to 500 μm.
In a preferred embodiment of the present invention, in the step (2), the coal gangue, the cement, the supplementary cementitious material, the gelling dispersant and the water are fully mixed for 1min under the conditions of normal temperature and pressure and a stirring speed of 30rpm to form the coal gangue-based paste with certain fluidity.
In a preferred embodiment of the present invention, wherein, in step (2), the coal gangue has a particle size of 4.75-20mm, and the coal gangue in this particle size range mainly serves as a coarse aggregate in the paste system to play a system supporting role; preferably, the oversized coal refuse is subjected to a conventional crusher, such as a cone crusher, to control the particle size.
In a preferred embodiment of the present invention, wherein in step (2), the cement is ordinary portland cement with a mark no less than p.o.42.5.
In a preferred embodiment of the present invention, in step (2), the supplementary cementitious material is at least one selected from fly ash, carbide slag and desulfurized gypsum.
In a preferred embodiment of the present invention, wherein, in the step (2), the mass ratio of the coal gangue, the cement, the auxiliary cementing material, the gelling dispersant and the water is 1400-1700: 50-100: 250-350: 250-300: 100-200.
In a preferred embodiment of the present invention, in the step (2), an additive is added in an amount of not more than 0.5 wt% of the gangue-based paste, and the additive is selected from acrylic compounds, preferably acrylic acid and/or methacrylic acid.
In a preferred embodiment of the present invention, wherein, in the step (3), the time of the secondary carbonation reaction is 5 to 10 min.
In a preferred embodiment of the present invention, wherein, in step (3), in order to ensure sufficient carbonation reaction activity, the second CO 2 In the gas, CO 2 The volume concentration of (a) is 60-99%.
In a preferred embodiment of the present invention, in step (3), the gangue-based paste with certain fluidity is stirred at 25-30rpm at normal temperature and pressure to produce the carbonated gangue-based paste 180m 3 Calculated as/h, feeding a second CO 2 Gas, performing a secondary carbonation reaction, wherein the second CO is 2 Gas with CO 2 The mass flow rate is 60-120 kg/h; preferably, the second CO 2 Gas is injected into the stirring paste from the top of the reactor.
In a preferred embodiment of the present invention, wherein the first CO is 2 Gas and second CO 2 The gases come from the flue gas CO of thermal power generation 2 Petrochemical purge gas CO 2 Coal chemical industry tail gas CO 2 And carbon-containing tail gas in industrial processes of the steel and cement industries.
According to the invention, the gelled dispersant obtained by the primary carbonation reaction can play a good role in system dispersion in the secondary carbonation reaction process, and is particularly reflected in that the carbon dioxide reaction efficiency is improved, so that the secondary carbonation reaction is carried out more efficiently and rapidly, and a stable carbonate phase is further generated in the paste forming process by matching with the secondary carbonation reaction of the gelled dispersant, so that the microstructure of the paste is more compact and continuous, and the strength and the soaking resistance of the paste are further enhanced, and the leaching inhibition effect on internal heavy metal ions is achieved.
In a second aspect of the present invention, a carbonated gangue-based paste is provided, wherein the carbonated gangue-based paste is obtained by the method of the first aspect.
In the invention, the carbonated gangue-based paste has good tolerance in an underground humid environment, can effectively avoid the corrosion of the paste caused by the underground humid environment so as to ensure that the strength loss does not occur, and simultaneously inhibits the pollution of heavy metal ions in solid waste raw materials on an underground water circulating system due to leaching.
The third aspect of the invention provides the application of the carbonated gangue-based paste of the second aspect in underground backfilling of a coal mine goaf.
The present invention will be described in detail below by way of examples.
In the following examples and comparative examples, the coal gangue is derived from waste slag discharged in the coal mine excavation and mining process of Shendong Jinjie of the national energy group; ordinary portland cement is ordinary portland cement from the shanghai conch cement supply, numbered: p.o.42.5.
In the following examples and comparative examples, the carbon fixation rates of the cement components were measured by a thermogravimetric analyzer (TGA); the uniaxial compressive strength is measured by a universal tester; cu in water 2+ The ion concentration was determined by inductively coupled plasma emission spectroscopy (ICP-OES).
Example 1
(1) Grinding the carbide slag in a grinder, sieving after grinding, sieving by a sieve of 500 mu m, and taking the carbide slag powder of 100-500 mu m below the sieve;
(2) mixing water and the carbide slag powder obtained in the step (1) according to a mass ratio of 15: 1 to obtain slurry with pH of 12.3, placing the slurry in a first-stage carbonation reactor, and introducing first CO with flow rate of 100mL/min and volume concentration of 20% under stirring at 100rpm 2 Performing primary carbonation reaction on the gas for 30min, wherein the carbide slag powder and the first CO 2 CO in gas 2 The mass ratio of (1): 1.5, separating and drying the obtained precipitate to obtain the gelling dispersant with the particle size of 100-;
(3) putting the coal gangue into a crusher, performing primary crushing, and then screening, and reserving stone-shaped coal gangue blocks on a 4.75mm sieve and below the 20mm sieve;
(4) and (3) mixing the gelling dispersant obtained in the step (2), the coal gangue obtained in the step (3), cement, an auxiliary cementing material (fly ash) and an additive (polyacrylic acid) according to a mass part ratio of 258: 1672: 60: 252: 8, fully mixing in a paste mixer, adding 150 parts by mass of water, and stirring at the speed of 30rpm to obtain a uniform flowing paste;
(5) opening the solenoid valve connected to the carbonator reactor, and 99% by volume of the second CO 2 After the gas passes through the mass flow meter, adjusting and controlling the second CO 2 CO in gas 2 The discharge flow is 90 kg/h;
(6) sending the uniform flowing paste obtained in the step (4) into a secondary carbonation reactor, and introducing CO with the flow rate in the step (5) from the top of the reactor 2 Continuously stirring at the rotating speed of 30rpm for 7min, and then finishing the secondary carbonation reaction to obtain paste with the slump of 121mm, wherein the initial setting time of the paste is 320min, and the final setting time is 370 min;
(7) and (4) injecting the paste obtained after the second-stage carbonation reaction in the step (6) into a cubic body die with the thickness of 10mm multiplied by 10mm for sealing and forming, and curing for 48 hours under natural conditions to obtain the carbonated coal gangue base paste.
Performing thermogravimetric analysis on the paste obtained in the step (6) to obtain a paste cement component with the carbon fixation rate of 4.7g-CO 2 Kg cement, as shown in FIG. 2; the uniaxial compressive strength of the carbonated gangue-based paste obtained in step (7) is 6.3MPa, as shown in fig. 3; and (4) soaking the formed paste in the step (7) in 20L of deionized water for 14d, and measuring the uniaxial compressive strength of the soaked paste to be 6.8MPa, as shown in figure 3.
Example 2
(1) Grinding the carbide slag in a grinder, sieving after grinding, sieving by a sieve of 500 mu m, and taking the carbide slag powder of 500 mu m below the sieve of 100-;
(2) mixing water and the carbide slag powder obtained in the step (1) according to a mass ratio of 15: 1 to obtain slurry with the pH value of 12.4, placing the slurry into a first-stage carbonation reactor, and introducing first CO with the flow rate of 100mL/min and the volume concentration of 20 percent under the stirring of 100rpm 2 Performing primary carbonation reaction on the gas for 30min, wherein the carbide slag powder and the first CO 2 CO in gas 2 The mass ratio of (1): 1.5, separating and drying the obtained precipitate to obtain the gelling dispersant with the particle size of 100-;
(3) putting the coal gangue into a crusher, performing primary crushing, and then screening, and reserving stone-shaped coal gangue blocks on a 4.75mm sieve and below a 20mm sieve;
(4) and (3) mixing the gelling dispersant obtained in the step (1), the coal gangue obtained in the step (2), cement, an auxiliary cementing material (fly ash) and an additive (polyacrylic acid) according to a mass part ratio of 258: 1672: 60: 252: 8, fully mixing in a paste mixer, adding 150 parts by mass of water, and stirring at the speed of 30rpm to obtain a uniform flowing paste;
(5) opening the solenoid valve connected to the carbonator reactor, and 99% by volume of the second CO 2 After the gas passes through the mass flow meter, adjusting and controlling the second CO 2 CO in gas 2 The discharge flow is 60 kg/h;
(6) sending the uniform flowing paste obtained in the step (4) into a secondary carbonation reactor, and introducing CO with the flow rate in the step (5) from the top of the reactor 2 Continuously stirring at the rotating speed of 30rpm for 5min, and then finishing the secondary carbonation reaction to obtain paste with the slump of 128mm, wherein the initial setting time of the paste is 350min, and the final setting time of the paste is 400 min;
(7) and (4) injecting the paste obtained after the secondary carbonation reaction in the step (6) into a cubic die with the thickness of 10mm multiplied by 10mm for sealing and forming, and curing for 48 hours under natural conditions to obtain the carbonated coal gangue base paste.
Performing thermogravimetric analysis on the paste obtained in the step (6) to obtain a paste cement component with a carbon fixation rate of 2.3g-CO 2 Kg cement, as shown in FIG. 2; the single-axis compressive strength of the carbonated gangue-based paste obtained in step (7) is 4.7MPa, as shown in fig. 3; and (3) soaking the formed paste in the step (7) in 20L of deionized water for 14d, and measuring the uniaxial compressive strength of the soaked paste to be 4.8MPa, as shown in figure 3.
Example 3
(1) Grinding the carbide slag in a grinder, sieving after grinding, sieving by a sieve of 500 mu m, and taking the carbide slag powder of 100-500 mu m below the sieve;
(2) mixing water and the carbide slag powder obtained in the step (1) according to a mass ratio of 15: 1 to obtain slurry with the pH value of 12.3, placing the slurry in a first-stage carbonation reactor, and introducing first CO with the flow rate of 100mL/min and the volume concentration of 20 percent under the stirring of 100rpm 2 Performing primary carbonation reaction on the gas for 30min, wherein the carbide slag powder and the first CO 2 CO in gas 2 The mass ratio of (1): 1.5, separating and drying the obtained precipitate to obtain the gelling dispersant with the particle size of 100-;
(3) putting the coal gangue into a crusher, performing primary crushing, and then screening, and reserving stone-shaped coal gangue blocks on a 4.75mm sieve and below a 20mm sieve;
(4) and (2) mixing the gelling dispersant obtained in the step (1), the coal gangue obtained in the step (3), cement, an auxiliary cementing material (fly ash) and an additive (polyacrylic acid) according to a mass part ratio of 258: 1672: 60: 252: 8, fully mixing in a paste mixer, adding 150 parts by mass of water, and stirring at the speed of 30rpm to obtain a uniform flowing paste;
(5) opening the solenoid valve connected to the carbonator reactor, and 99% by volume of the second CO 2 After the gas passes through the mass flow meter, adjusting and controlling the second CO 2 CO in gas 2 The discharge flow is 120 kg/h;
(6) feeding the uniform flowing paste obtained in the step (4) into a secondary carbonation reactor, and introducing CO with the flow rate in the step (5) from the top of the secondary carbonation reactor 2 Continuously stirring at the rotating speed of 30rpm for 10min, and then finishing the secondary carbonation reaction to obtain paste with the slump of 114mm, wherein the initial setting time of the paste is 335min, and the final setting time is 385 min;
(7) and (4) injecting the paste obtained after the second-stage carbonation reaction in the step (6) into a cubic body die with the thickness of 10mm multiplied by 10mm for sealing and forming, and curing for 48 hours under natural conditions to obtain the carbonated coal gangue base paste.
Performing thermogravimetric analysis on the paste obtained in the step (6) to obtain a paste cement component with the carbon fixation rate of 3.8g-CO 2 Kg cement, as shown in FIG. 2; the single-axis compressive strength of the carbonated gangue-based paste obtained in step (7) is 5.8MPa, as shown in fig. 3; and (3) soaking the formed paste in the step (7) in 20L of deionized water for 14d, and measuring the uniaxial compressive strength of the soaked paste to be 6.1MPa, as shown in figure 3.
Example 4
The same procedure as in example 1 was repeated, except that 2.5% by mass of copper nitrate was added in step (4), and the heavy metal release behavior was verified under magnification. Soaking the formed paste for 48h under natural curing condition in 20L deionized water for 14d, and measuring Cu in the water 2+ The ion mass concentration was 0.17ppm, as shown in FIG. 4.
Comparative example 1
(1) Grinding the carbide slag in a grinder, sieving after grinding, sieving by a sieve of 500 mu m, and taking the carbide slag powder of 100-500 mu m below the sieve;
(2) mixing water and the carbide slag powder obtained in the step (1) according to a mass ratio of 15: 1, the pH of the slurry is 12.5, the slurry is placed in a first-stage carbonation reactor, and under the stirring of 100rpm, first CO with the flow rate of 100mL/min and the volume concentration of 20 percent is introduced 2 Performing primary carbonation reaction on the gas for 30min, wherein the carbide slag powder and the first CO 2 CO in gas 2 The mass ratio of (1): 1.5, separating and drying the obtained precipitate to obtain the gelling dispersant with the particle size of 100-;
(3) putting the coal gangue into a crusher, performing primary crushing, and then screening, and reserving stone-shaped coal gangue blocks on a 4.75mm sieve and below a 20mm sieve;
(4) and (2) mixing the gelling dispersant obtained in the step (1), the coal gangue obtained in the step (3), cement, an auxiliary cementing material (fly ash) and an additive (polyacrylic acid) according to a mass part ratio of 258: 1672: 60: 252: 8, fully mixing in a paste mixer, adding 150 parts by mass of water, and stirring at the speed of 30rpm to obtain a uniform flowing paste;
(5) opening the solenoid valve connected to the carbonator reactor, and 99% by volume of the second CO 2 After the gas passes through the mass flow meter, adjusting and controlling the second CO 2 CO in gas 2 The discharge flow is 0 kg/h;
(6) sending the uniformly flowing paste obtained in the step (4) into a secondary carbonation reactor, and continuously stirring at the rotating speed of 30rpm for 10min to obtain a paste with the slump of 148mm, wherein the initial setting time of the paste is 420min, and the final setting time of the paste is 470 min;
(7) and (4) injecting the paste obtained in the step (6) into a 10mm multiplied by 10mm cubic body die for sealing and molding, and curing for 48 hours under natural conditions to obtain the carbonated coal gangue base paste.
Performing thermogravimetric analysis on the paste obtained in the step (6) to obtain a paste cement component with a carbon fixation rate of 0g-CO 2 Kg cement, as shown in FIG. 2; the single-axis compressive strength of the carbonated gangue-based paste obtained in step (7) is 4.3MPa, as shown in fig. 3; soaking the formed paste in the step (7) in the step 2The uniaxial compressive strength of the soaked paste was measured to be 3.7MPa in 0L of deionized water for 14d, as shown in FIG. 3.
Comparative example 2
(1) Grinding the carbide slag in a grinder, sieving after grinding, sieving by a sieve of 500 mu m, and taking the carbide slag powder of 100-500 mu m below the sieve;
(2) putting the coal gangue into a crusher, performing primary crushing, and then screening, and reserving stone-shaped coal gangue blocks on a 4.75mm sieve and below a 20mm sieve;
(3) directly mixing the carbide slag powder obtained in the step (1), the coal gangue obtained in the step (2), cement, an auxiliary cementing material (fly ash) and an additive (polyacrylic acid) according to a mass part ratio of 258: 1672: 60: 252: 8, fully mixing in a paste mixer, adding 150 parts by mass of water, and stirring at the speed of 30rpm to obtain a uniform flowing paste;
(4) opening the solenoid valve connected to the carbonator reactor, and 99% by volume of the second CO 2 After the gas passes through the mass flow meter, adjusting and controlling the second CO 2 CO in gas 2 The discharge flow is 60 kg/h;
(5) feeding the uniformly flowing paste in the step (3) into a secondary carbonation reactor, and introducing CO in the state of the step (4) from the top of the secondary carbonation reactor 2 Continuously stirring at the rotating speed of 30rpm for 10min, and then finishing carbonation reaction to obtain paste with slump of 126mm, wherein the initial setting time of the paste is 340min, and the final setting time is 385 min;
(6) and (4) injecting the paste after the carbonation reaction in the step (5) into a cubic body die with the thickness of 10mm multiplied by 10mm for sealing and molding, and curing for 48 hours under natural conditions to obtain the carbonated coal gangue base paste.
Performing thermogravimetric analysis on the paste obtained in the step (5) to obtain a paste cement component with a carbon fixation rate of 1.3g-CO 2 Kg cement, as shown in FIG. 2; the single-axis compressive strength of the carbonated gangue-based paste obtained in step (6) is 4.1MPa, as shown in fig. 3; and (4) soaking the formed paste in the step (6) in 20L of deionized water for 14d, and measuring the uniaxial compressive strength of the soaked paste to be 4.0MPa, as shown in figure 3.
Comparative example 3
The same procedure as in comparative example 1 was followed, except that 2.5% by mass of copper nitrate was added in step (4), and the heavy metal release behavior was verified under magnification. Soaking the formed paste for 48h under natural curing condition in 20L deionized water for 14d, and measuring Cu in the water 2+ The mass concentration of the ion is 1.21ppm as shown in FIG. 4.
Comparative example 4
The same procedure as in comparative example 2 was followed, except that 2.5% by mass of copper nitrate was added in step (4), and the heavy metal release behavior was verified under magnification. Soaking the formed paste for 48h under natural curing condition in 20L deionized water for 14d, and measuring Cu in the water 2+ The ion mass concentration of 0.89ppm is shown in FIG. 4.
As can be seen from FIG. 2, the cement component carbon fixation rate of the pastes obtained in examples 1 to 3 was higher than that of comparative examples 1 to 2; as can be seen from FIG. 3, the paste obtained in examples 1 to 3 had higher uniaxial compressive strength than that obtained in comparative examples 1 to 2, and the paste obtained in examples 1 to 3 had slightly increased uniaxial compressive strength after being soaked for 14 days, while the paste obtained in comparative examples 1 to 2 had decreased uniaxial compressive strength after being soaked for 14 days; as can be seen from FIG. 4, Cu was obtained after the paste obtained in example 4 was soaked for 14 days 2+ The mass concentration of the leached paste is 0.17ppm, and Cu is obtained after the paste prepared in comparative examples 3-4 is soaked for 14 days 2+ The leaching mass concentrations are 1.21ppm and 0.89ppm respectively. Therefore, the carbonated coal gangue-based paste prepared by the method provided by the invention has good tolerance in a humid environment, can keep the compressive strength in an underground humid environment, and effectively inhibits the leaching of heavy metal ions in solid wastes to avoid the pollution of the heavy metal ions to an underground water circulating system, thereby meeting the application requirement of the carbonated coal gangue-based paste for underground backfilling of a coal mine goaf.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including various technical features being combined in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A preparation method of carbonated gangue-based paste is characterized by comprising the following steps:
(1) introducing first CO into slurry obtained by mixing alkaline industrial solid waste and water 2 Performing primary carbonation reaction on the gas, separating out precipitate and drying to obtain a gelling dispersant;
(2) mixing coal gangue, cement, an auxiliary cementing material, the cementing dispersant and water to obtain a coal gangue-based paste;
(3) under the stirring state, introducing second CO into the coal gangue base paste 2 And performing secondary carbonation reaction, sealing, forming and naturally curing to obtain the carbonated coal gangue base paste.
2. The method of claim 1, wherein in step (1), the alkaline industrial solid waste is selected from at least one of carbide slag, steel slag, desulfurized slag, blast furnace slag;
preferably, the particle size of the alkaline industrial solid waste is 100-500 μm;
preferably, the mass ratio of the alkaline industrial solid waste to the water is 1: 5-15;
preferably, the slurry pH is not less than 12.
3. The process according to claim 1 or 2, wherein in step (1), the primary carbonation reaction is carried out for a period of 20-30 min;
preferably, the alkaline industrial solid waste and first CO 2 CO in gas 2 The mass ratio of (1): 0.5 to 2;
preferably, the first CO 2 In the gas, CO 2 The volume concentration of (A) is 10-30%;
preferably, the first CO 2 The volume flow of the gas is 100-500 mL/min;
preferably, the particle size of the gel dispersing agent is less than or equal to 500 mu m.
4. The process according to any one of claims 1 to 3, wherein, in step (2), the coal gangue has a particle size of 4.75-20 mm;
the cement is ordinary portland cement, and the grade of the cement is not lower than P.O.42.5.
5. The method according to any one of claims 1 to 4, wherein in step (2), the supplementary cementitious material is selected from at least one of fly ash, carbide slag and desulfurized gypsum.
6. The method as claimed in any one of claims 1 to 5, wherein in the step (2), the mass ratio of the coal gangue, cement, supplementary cementitious material, cementitious dispersant and water is 1400-1700: 50-100: 250-350: 250-300: 100-;
preferably, in the step (2), an additive is added in an amount of not more than 0.5 wt% of the gangue-based paste, wherein the additive is selected from acrylic compounds, preferably acrylic acid and/or methacrylic acid.
7. The process according to any one of claims 1 to 6, wherein in step (3), the secondary carbonation reaction is carried out for a period of 5 to 10 min;
preferably, the second CO 2 In the gas, CO 2 The volume concentration of (A) is 60-99%;
preferably, the carbonated gangue-based paste is produced by 180m 3 Calculated as/h, the second CO 2 Gas with CO 2 The mass flow rate is 60-120 kg/h.
8. The method of any of claims 1-7, wherein the first CO is 2 Gas and second CO 2 The gases come from the flue gas CO of thermal power generation 2 Petrochemical purge gas CO 2 Coal chemical industry tail gas CO 2 And carbon-containing tail gas in industrial processes of steel and cement industries.
9. A carbonated gangue-based paste, characterized in that it is obtained by the process according to any one of claims 1-8.
10. Use of the carbonated gangue-based paste of claim 9 in the downhole backfill of a goaf in a coal mine.
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