CN115504638B - Carbon dioxide mineralization maintenance method for river and lake dredging bottom mud - Google Patents
Carbon dioxide mineralization maintenance method for river and lake dredging bottom mud Download PDFInfo
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- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
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- 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
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- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
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Abstract
The invention provides a carbon dioxide mineralization maintenance method of river and lake dredging sediment, which comprises the following steps: preparing a curing agent; preparing solidified sludge; paving water permeable template cloth outside the first die template; pouring solidified sludge with the water content more than 60% into the first mould; a plurality of first molds loaded with solidified sludge with the water content more than 60% are sequentially arranged in a bracket at intervals from bottom to top; placing the bracket in a closed curing space for carbon dioxide mineralization curing; pouring the solidified sludge with the water content less than or equal to 60% into a second mould, and compacting the solidified sludge in the second mould by a press machine to form a porous sludge building block; and conveying the second die into a closed curing space for carbon dioxide mineralization curing. The invention can effectively neutralize the pH of the sludge, rapidly improve the early strength and hardness of the sludge, further enhance the compactness of the sludge structure and lead the solidified sludge to have wide application prospect; carbon dioxide can be consumed, and the greenhouse effect is reduced.
Description
Technical Field
The invention relates to the technical field of mineralization maintenance of sludge, in particular to a carbon dioxide mineralization maintenance method of river and lake dredging bottom sludge.
Background
A large amount of river and lake dredging bottom mud is produced annually in the projects of port construction, channel dredging, city and lake treatment and the like. If the huge amount of river and lake dredging bottom mud is treated by adopting a traditional landfill mode or ocean dumping mode, a great amount of land occupation and ocean pollution are easily caused. River and lake dredging bottom mud is difficult to treat due to the characteristics of high water content, high compressibility, low strength, high permeability and the like, and is difficult to directly apply to engineering.
At present, the application mode of river and lake dredging bottom mud at home and abroad mainly adopts cementing materials such as cement, lime and the like to solidify, so that stable and strong soil is formed, the problem of discarding the mud is alleviated to a certain extent, but the following problems exist: firstly, the mass consumption of cement and lime has the problems of resource waste, overhigh cost and greenhouse effect; secondly, the engineering application value is low and the environmental protection effect is poor due to the fact that the alkalinity of the solidified sludge is too high.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a carbon dioxide mineralization maintenance method for dredging bottom mud of a river and a lake, which not only can effectively neutralize the pH value of the mud, quickly improve the early strength and hardness of the mud, further enhance the compactness of a mud structure and lead the solidified mud to have wide application prospect; carbon dioxide can be consumed, the greenhouse effect is reduced, and the aim of carbon neutralization is fulfilled.
In order to achieve the aim, the invention provides a carbon dioxide mineralization maintenance method for river and lake dredging bottom mud, which is characterized by comprising the following steps:
step 1), dry stirring a large amount of solid waste materials and a small amount of gel materials, and fully mixing to form a curing agent for standby;
step 2), stirring the curing agent and the river and lake dredging substrate sludge in a stirrer, adding stirring water to obtain cured sludge, wherein the cured sludge with the water content of more than 60% enters the steps 3) to 6), and the cured sludge with the water content of less than or equal to 60% enters the steps 7) to 8);
step 3), tightly attaching the water permeable template cloth attached with the water absorbent resin to the outer side of the template wall of the first die, wherein first through holes are formed in the template wall at the bottom of the first die and the template walls around the template wall, and the first through holes penetrate into the first die, so that a porous structure is formed in the first die;
step 4), pouring solidified sludge with the water content more than 60% into the first die, and absorbing excessive water on the surface layer of the solidified sludge by using permeable template cloth on the outer side of the template wall of the first die so as to reduce the water content of the solidified sludge;
step 5), sequentially installing a plurality of first molds loaded with solidified sludge with the water content more than 60% in the bracket at intervals from bottom to top, wherein a gap channel is arranged between every two adjacent first molds;
step 6), placing the bracket loaded with a plurality of first molds in a closed curing space, introducing industrial waste carbon dioxide gas into the closed curing space, enabling the carbon dioxide gas to enter a water-permeable template cloth outside the template wall of the first mold through a gap channel, then enabling the carbon dioxide gas to continuously enter a porous structure inside the solidified sludge through a first through hole, absorbing the carbon dioxide gas by steel slag around the porous structure to generate carbonation reaction, generating stable calcium carbonate and magnesium carbonate, rapidly mineralizing a large amount of solidified sludge in a short time, shortening the mineralization curing time of the solidified sludge, reducing the strong alkalinity of the solidified sludge, and neutralizing and adjusting the pH value of soil with low alkalinity;
step 7), pouring the solidified sludge with the water content less than or equal to 60% into a second mould, wherein a second through hole is formed in the wall of a template at the bottom of the second mould, then compacting the solidified sludge in the second mould through a press, and a press head of the press is provided with pressure rods which are in one-to-one correspondence with the second through holes, so that the extruded solidified sludge forms a porous sludge block;
step 8), conveying a second die provided with the porous sludge building blocks into the closed curing space, introducing industrial waste carbon dioxide gas, enabling the carbon dioxide gas to enter a porous structure inside the porous sludge building blocks through a second through hole, enabling steel slag around the porous structure to absorb the carbon dioxide gas to perform carbonation reaction, generating stable calcium carbonate and magnesium carbonate, and improving the structural strength and compactness inside the solidified sludge.
Further, in the step 1), the solid waste material comprises steel slag, slag and fly ash; the gel material comprises cement, limestone powder and bentonite.
Further, in the step 1), the curing agent comprises 65 to 75 percent of steel slag powder, 5 to 15 percent of fly ash, 5 to 10 percent of cement, 2 to 5 percent of limestone powder, 2 to 5 percent of bentonite and 0.1 to 1 percent of flocculating agent.
Further, in the step 1), the average grain size of the steel slag powder is 10 to 20 mu m, wherein SiO 2 The content is 5-10%, caO content is 50-70%, mgO content is 5-10%;
the activity index of the slag powder is more than S95, the average grain diameter is 1-100 mu m, and the specific surface area is more than 400m 2 /kg；
The national standard grade of the fly ash is more than grade II, the average grain diameter is 1-100 mu m, and the specific surface area is more than 300m 2 /kg；
The cement is Portland cement with the strength of more than or equal to 42.5 levels;
the limestone powder has average particle size of not more than 80nm, and CaCO 3 The content is more than 95 percent;
the bentonite has an average particle size of more than 38 mu m, wherein the montmorillonite component is more than 83%;
the flocculant consists of one or more of polyacrylamide, calcium acrylate and sodium polyacrylate, and the particle size is 50-200 mu m.
Further, in the step 3), the opening ratio of the first die is 70% -80%.
Further, in the step 3), the first through hole is a square hole with a size of 10 mm-20 mm.
Further, in the step 7), the aperture ratio of the bottom template wall of the second mold is 40% -50%.
In step 7), the second through hole is arranged in a round hole with a size of 10 mm-12 mm at four corners, a round hole with a size of 15 mm-20 mm at the middle position and square holes with a size of 10 mm-15 mm at the rest positions.
Further, in step 6) and step 8), the concentration of the carbon dioxide gas is more than 30%.
The invention has the advantages that:
1. firstly, preparing the sludge into solidified sludge with different water contents by mixing solid waste and gel materials into the sludge, and respectively adopting two different mineralization curing processes for the solidified sludge according to the water contents of the solidified sludge to prepare mineralized products with different purposes;
2. aiming at the solidified sludge with the water content of more than 60 percent, in view of the flowing state characteristics of the solidified sludge, the solidified sludge with the water content of more than 60 percent is filled into a first die with the aperture ratio of 70-80 percent, and the water content of the solidified sludge is reduced by absorbing the surplus water on the surface layer of the solidified sludge through a permeable template cloth arranged outside the first die; meanwhile, a plurality of first dies for loading the solidified sludge with the water content more than 60% are sequentially arranged in the bracket at intervals from bottom to top, mineralized curing quantity of the solidified sludge is increased in a certain closed curing space, carbon dioxide gas flows into a gap channel between the adjacent first dies to enter an internal porous structure of the solidified sludge in the first dies, so that a large amount of solidified sludge is rapidly mineralized in a short time on one hand, mineralized curing time of the solidified sludge is shortened, and on the other hand, the solidified sludge can be used as a soil conditioner to reduce the strong alkalinity of the solidified sludge and neutralize and adjust the pH value of the soil with low alkalinity, so that the mineralized and cured solidified sludge can be used for garden planting and farmland crop planting;
3. aiming at the solidified sludge with the water content less than or equal to 60 percent, in view of the plastic state characteristics of the solidified sludge, the solidified sludge with the water content less than or equal to 60 percent is filled into a second die with the opening rate of 40 to 50 percent of the wall of the bottom die plate, and the solidified sludge in the second die is compacted by a press machine, so that the extruded solidified sludge forms a porous sludge block; carbon dioxide gas flows into the porous structure in the porous sludge block to promote the steel slag around the porous structure to absorb the carbon dioxide gas to generate carbonation reaction, so that stable calcium carbonate and magnesium carbonate are generated, the structural strength and compactness of the inside of the solidified sludge are improved, and the mineralized and maintained porous sludge block can replace common porous bricks and sintered clay bricks and is used for various non-bearing and frame filling building wall structures;
the carbon dioxide mineralization maintenance method of the river and lake dredging bottom mud can effectively neutralize the pH of the mud, rapidly improve the early strength and hardness of the mud, further enhance the compactness of the mud structure and widen the engineering application range of the solidified mud; and the carbon dioxide can be consumed, the greenhouse effect is reduced, the aim of carbon neutralization is fulfilled, and the method is an effective mode for capturing, utilizing and sealing carbon and has good economic and environmental benefits.
Drawings
FIG. 1 is a flow chart of a method for mineralizing and maintaining carbon dioxide in river and lake dredging sediment according to the invention;
FIG. 2 is a schematic diagram of a front cross-sectional structure of a first mold installed in a bracket in the carbon dioxide mineralization curing method of river and lake dredging bottom mud;
FIG. 3 is a schematic top view of the bottom template wall of a second mold in the method for mineralizing and curing the carbon dioxide of the river and lake dredging bottom mud of the invention;
FIG. 4 is a schematic diagram of a production device of a porous sludge block in the carbon dioxide mineralization maintenance method of river and lake dredging bottom sludge;
in the figure: the device comprises a first die 1, a bracket 2, a second die 3, a press 4, water permeable template cloth 5, a closed curing space 6, a solidified sludge hopper 7 and a conveying belt 8;
the first mold 1 includes: a first through hole 1-1;
the bracket 2 includes: a clearance channel 2-1;
the second mold 3 includes: a second through hole 3-1;
the press 4 includes: a pressure rod 4-1.
Detailed Description
The invention is described in further detail below with reference to the drawings and specific examples.
In the description of the present invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the invention.
The carbon dioxide mineralization maintenance method of the dredging bottom mud of the river and the lake, as shown in figure 1, comprises the following steps:
and 1) dry stirring a large amount of solid waste materials and a small amount of gel materials, and fully mixing to form a curing agent for standby. Specifically, the solid waste material comprises steel slag, slag and fly ash; the gel material comprises cement, limestone powder and bentonite.
Preferably, the curing agent comprises 65-75% of steel slag powder, 5-15% of fly ash, 5-10% of cement, 2-5% of limestone powder, 2-5% of bentonite and 0.1-1% of flocculant. Wherein the average grain diameter of the steel slag powder is 10-20 mu m, wherein SiO 2 The content is 5-10%, caO content is 50-70%, mgO content is 5-10%;
the activity index of the slag powder is more than S95, the average grain diameter is 1-100 mu m, and the specific surface area is more than 400m 2 /kg；
The national standard grade of the fly ash is more than grade II, the average grain diameter is 1-100 mu m, and the specific surface area is more than 300m 2 /kg；
The cement is Portland cement with the strength of more than or equal to 42.5 levels;
the limestone powder has average particle size of not more than 80nm, and CaCO 3 The content is more than 95 percent;
the bentonite has an average particle size of more than 38 mu m, wherein the montmorillonite component is more than 83%;
the flocculant consists of one or more of polyacrylamide, calcium acrylate and sodium polyacrylate, and the particle size is 50-200 mu m.
Step 2), stirring the curing agent and the river and lake dredging substrate sludge in a stirrer, adding stirring water to obtain cured sludge, wherein the cured sludge with the water content of more than 60% enters the steps 3) to 6), and the cured sludge with the water content of less than or equal to 60% enters the steps 7) to 8).
According to the invention, firstly, steel slag and gel materials are doped into the sludge, so that the sludge is prepared into solidified sludge with different water contents, and two different mineralization curing processes are respectively adopted for the solidified sludge according to the water content of the solidified sludge, so that mineralized products with different purposes are prepared.
Step 3), step 3) the water permeable template cloth 5 attached with the water absorbent resin is tightly attached to the outer side of the template wall of the first mould 1, the template wall at the bottom of the first mould 1 and the template walls around the first mould 1 are provided with first through holes 1-1, and the first through holes 1-1 penetrate into the first mould 1, so that a porous structure is formed in the first mould 1.
Specifically, the opening ratio of the first mold 1 is 70% -80%, and the first through hole 1-1 is a square hole with a size of 10 mm-20 mm, as shown in fig. 2.
And 4) pouring solidified sludge with the water content more than 60% into the first mould 1, absorbing the surplus water on the surface layer of the solidified sludge by using the permeable template cloth 5 on the outer side of the template wall of the first mould 1, and reducing the water content of the solidified sludge.
Step 5), then a plurality of first dies 1 loaded with solidified sludge with the water content more than 60% are sequentially arranged in the bracket 2 at intervals from bottom to top, and a gap channel 2-1 is arranged between every two adjacent first dies 1.
And 6) placing the bracket 2 loaded with a plurality of first molds 1 in a closed curing space 6, introducing industrial waste carbon dioxide gas into the closed curing space 6, wherein the concentration of the carbon dioxide gas is more than 30%, the carbon dioxide gas enters a permeable template cloth 5 outside the template wall of the first molds 1 through a gap channel 2-1, then continuously enters a porous structure inside the solidified sludge through a first through hole 1-1, and the steel slag around the porous structure absorbs the carbon dioxide gas to carry out carbonation reaction to generate stable calcium carbonate and magnesium carbonate, so that a large amount of solidified sludge is rapidly mineralized in a short time, the mineralization curing time of the solidified sludge is shortened, the strong alkalinity of the solidified sludge is reduced, and the pH value of soil is neutralized and adjusted by low alkalinity.
Aiming at the solidified sludge with the water content of more than 60 percent, in view of the flowing state characteristics of the solidified sludge, the solidified sludge with the water content of more than 60 percent is filled into the first mould 1 with the aperture ratio of 70-80 percent, and the water content of the solidified sludge is reduced by absorbing the surplus water on the surface layer of the solidified sludge through the permeable template cloth 5 arranged on the outer side of the template wall of the first mould 1; simultaneously, a plurality of first dies 1 loaded with solidified sludge with the water content more than 60% are sequentially arranged in a bracket 2 at intervals from bottom to top, mineralization curing quantity of the solidified sludge is increased in a certain closed curing space, carbon dioxide gas flows into an inner porous structure of the solidified sludge in the first dies 1 through a gap channel 2-1 between adjacent first dies 1, a large amount of solidified sludge is rapidly mineralized in a short time, and mineralization curing time of the solidified sludge is shortened; on the other hand, the modified soil can also be used as a soil conditioner to reduce the strong alkalinity of the solidified sludge and neutralize and adjust the pH value of the soil with low alkalinity; in addition, the high-fineness converter slag can effectively promote the mineralization reaction of carbon dioxide, simultaneously provide calcium and magnesium ions, iron, aluminum and other metal ions for the soil to precipitate, fix heavy metals to ensure that the heavy metals are not easy to leach out, achieve the effect of restoring the ecology of the soil, and provide SiO (silicon dioxide) required by crops (such as rice) 2 And trace elements, so that the cured sludge after mineralization and maintenance can be used for garden planting and farmland crop planting. Therefore, the sludge, the solid waste and the carbon dioxide form a triple utilization benefit, have high value and high prospect, and lead the sludge, the solid waste and the carbon dioxide to be in high prospectAnd plays a role in more fields.
Step 7), pouring the solidified sludge with the water content less than or equal to 60% into a second mold 3, forming a second through hole 3-1 on the wall of a bottom template of the second mold 3, then compacting the solidified sludge in the second mold 3 through a press 4, and arranging pressure rods 4-1 in one-to-one correspondence with the second through holes 3-1 by a press head of the press 4, so that the extruded solidified sludge forms a porous sludge block, as shown in fig. 4.
Specifically, the aperture ratio of the bottom template wall of the second mold 3 is 40% -50%, the layout mode of the second through holes 3-1 is that round holes with the size of 10 mm-12 mm are arranged at four corners, round holes with the size of 15 mm-20 mm are arranged at the middle position, and square holes with the size of 10 mm-15 mm are arranged at the rest positions, as shown in fig. 3.
Step 8), conveying the second die 3 filled with the porous sludge blocks into the closed curing space 6, and introducing industrial waste carbon dioxide gas, wherein the concentration of the carbon dioxide gas is more than 30%, the carbon dioxide gas enters a porous structure in the porous sludge blocks through the second through holes 3-1, and steel slag around the porous structure absorbs the carbon dioxide gas to carry out carbonation reaction to generate stable calcium carbonate and magnesium carbonate, so that the structural strength and compactness of the inside of the solidified sludge are improved.
Aiming at the solidified sludge with the water content less than or equal to 60 percent, in view of the plastic state characteristics of the solidified sludge, the solidified sludge with the water content less than or equal to 60 percent is filled into the second mould 3 with the opening rate of 40 to 50 percent of the bottom mould wall, and the solidified sludge in the second mould 3 is compacted by the press 4, so that the extruded solidified sludge forms a porous sludge building block; carbon dioxide gas flows into the porous structure in the porous sludge block, so that the steel slag around the porous structure absorbs the carbon dioxide gas to generate carbonation reaction, stable calcium carbonate and magnesium carbonate are generated, the structural strength and compactness of the inside of the solidified sludge are improved, and the mineralized and maintained porous sludge block can replace common porous bricks and sintered clay bricks and is used for various non-bearing and frame filling building wall structures.
The invention aims to mineralize and cure the solidified sludge by adopting carbon dioxide, and the main purpose of curing is to improve the physical and mechanical properties so as to meet engineering application, so that the solidified sludge is prepared into a porous structure, and then the carbon dioxide is introduced, so that the solidified sludge is quickly carbonized, the problems of high alkalinity, small application range and the like of the solidified sludge are solved, the curing time of the solidified sludge is finally shortened, and the early strength and the structural compactness of the solidified sludge are improved. The method provides a direction for popularization and application of carbon dioxide mineralization maintenance and sludge solidification, and the combination of the two expands the application range of solidified sludge, thereby having good economic and environmental benefits.
The following is a specific example of sludge having initial water contents of 60%, 80% and 110%, respectively.
Comparative example 1:
curing sludge which is not subjected to carbon dioxide mineralization curing and only adopts conventional curing has water content of 60%, 80% and 110%, the mixing amount of the curing agent is 10% of the mass of the sludge, and the curing agent consists of the following components in mass: 70% of converter slag powder, 6% of ordinary portland cement, 10% of fly ash, 2% of limestone powder, 10% of slag, 2% of bentonite and 0.1% of flocculant.
The preparation process comprises the following steps:
1) Fully mixing steel slag powder, portland cement, fly ash, limestone powder, slag, bentonite and flocculant, and dry stirring for 2 minutes to form a curing agent for later use;
2) Placing the sludge and the curing agent in a stirrer to be stirred for 2 minutes;
3) Adding mixing water, and stirring for 5 minutes to obtain solidified sludge;
4) Placing the mixture into a common mould, and placing the mixture into a standard curing room for conventional curing.
The moisture content and pH index of the cured sludge after conventional curing are shown in Table 1 below.
TABLE 1 variation of the moisture content and pH index of conventionally cured sludge with curing time
The mechanical properties and pH indicators of the cured sludge after conventional curing are shown in Table 2 below.
TABLE 2 mechanical Properties and pH indicators of conventionally cured sludge
Example 1:
the method comprises the steps of preparing solidified sludge with a porous structure by adopting a first mould 1 (the internal opening ratio is 70%, and the first through holes 1-1 are square holes with the size of 10 mm), then carrying out carbon dioxide mineralization maintenance, and verifying the feasibility of the carbon dioxide mineralization maintenance of the solidified sludge by adopting different carbon dioxide concentrations.
The preparation process comprises the following steps:
1) A solidified sludge having an initial water content of 80% and 110% was prepared in the same manner as in comparative example 1, respectively;
2) The method comprises the steps of tightly attaching water-permeable template cloth 5 attached with water-absorbent resin to the outer side of a template wall of a first die 1, pouring solidified sludge into the first die 1, sequentially installing a plurality of first dies 1 loaded with the solidified sludge in a bracket 2 at intervals from bottom to top, and arranging a gap channel 2-1 between every two adjacent first dies 1;
3) And (3) placing the brackets 2 provided with a plurality of first moulds 1 into a closed curing space 6, and respectively adopting 30%, 60% and 99% carbon dioxide to carry out mineralization curing, wherein the curing time is 12h,24h and 48h.
The water content and the pH index of the solidified sludge after the mineralized and maintained carbon dioxide are shown in the following table 3.
TABLE 3 variation of the moisture content and pH index of the carbon dioxide mineralized cured sludge with curing time
Example 2:
and (3) carrying out carbon dioxide mineralization maintenance on the second die (3) (the aperture ratio is 40%, the layout mode of the second through holes (3-1) is that circular holes with the size of 10mm are arranged at four corners, circular holes with the size of 15mm are arranged at the middle position, square holes with the size of 12mm are arranged at the rest positions) and the porous sludge building blocks formed by press injection molding by a press, and verifying the feasibility of the carbon dioxide mineralization maintenance of the solidified sludge by adopting different carbon dioxide concentrations.
The preparation process comprises the following steps:
1) A solidified sludge having an initial water content of 60% was prepared in the same manner as in comparative example 1;
2) Pouring solidified sludge with the water content of 60% into a second mold 3, placing the second mold 3 on a conveying belt, and compacting the solidified sludge through a press 4 to form a porous sludge building block;
3) And (3) placing the second mould 3 filled with the porous sludge blocks in a conveying belt to convey the second mould into a closed curing space 6, and respectively adopting 30%, 60% and 99% carbon dioxide for mineralizing and curing for 72h,168h and 672h.
The water content and the pH index of the solidified sludge after the mineralized and maintained carbon dioxide are shown in the following table 4.
TABLE 4 mechanical Properties and pH indicators of cured sludge for mineralized curing of carbon dioxide
From the test results, it can be seen that:
(1) Example 1 and comparative example 1 show that the moisture content and pH of the solidified sludge in a flowing state show different changes under the curing of different carbon dioxide concentrations; with the increase of the concentration of the carbon dioxide, the water content and the pH value are greatly reduced, but the effect of the concentration is not obvious when the concentration is increased from 60% to 99%, so that the mineralization maintenance of the solidified sludge by the carbon dioxide with the concentration of 60% is optimal.
(2) As can be seen from the examples 2 and 1, taking the carbon dioxide concentration of 60% as an example, the unconfined compressive strength of 3d, 7d and 28d is rapidly improved, the unconfined compressive strength of 28d can be achieved by 3d, the shear strength of 28d is correspondingly improved after the carbon dioxide mineralization maintenance, and the pH value of 28d is reduced to 7-8, so that the treatment process of the example 2 can finish the reduction of the pH in a short time, and the strength of the porous sludge block is greatly improved.
The carbon dioxide mineralization maintenance method of the river and lake dredging bottom mud can effectively neutralize the pH of the mud, rapidly improve the early strength and hardness of the mud, further enhance the compactness of the mud structure and widen the engineering application range of the solidified mud; and the carbon dioxide can be consumed, the greenhouse effect is reduced, the aim of carbon neutralization is fulfilled, and the method is an effective mode for capturing, utilizing and sealing carbon and has good economic and environmental benefits.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (9)
1. The carbon dioxide mineralization maintenance method for the river and lake dredging bottom mud is characterized by comprising the following steps of:
step 1), dry stirring a large amount of solid waste materials and a small amount of gel materials, and fully mixing to form a curing agent for standby;
step 2), stirring the curing agent and the river and lake dredging substrate sludge in a stirrer, adding stirring water to obtain cured sludge, wherein the cured sludge with the water content of more than 60% enters the steps 3) to 6), and the cured sludge with the water content of less than or equal to 60% enters the steps 7) to 8);
step 3), tightly attaching a permeable template cloth (5) attached with water-absorbent resin to the outer side of a template wall of a first mold (1), wherein a first through hole (1-1) is formed in the template wall at the bottom of the first mold (1) and the template wall around the first mold, and the first through hole (1-1) penetrates into the first mold (1), so that a porous structure is formed in the first mold (1);
step 4), pouring solidified sludge with the water content more than 60% into the first mould (1), absorbing excessive water on the surface layer of the solidified sludge by using permeable template cloth (5) on the outer side of the template wall of the first mould (1), and reducing the water content of the solidified sludge;
step 5), sequentially installing a plurality of first molds (1) loaded with solidified sludge with the water content more than 60% in the bracket (2) at intervals from bottom to top, wherein a gap channel (2-1) is arranged between every two adjacent first molds (1);
step 6), placing a bracket (2) loaded with a plurality of first molds (1) in a closed curing space (6), introducing industrial waste carbon dioxide gas into the closed curing space (6), allowing the carbon dioxide gas to enter a permeable template cloth (5) outside the template wall of the first molds (1) through a clearance channel (2-1), then allowing the permeable template cloth to continuously enter a porous structure inside the solidified sludge through a first through hole (1-1), allowing steel slag around the porous structure to absorb the carbon dioxide gas to perform carbonation reaction to generate stable calcium carbonate and magnesium carbonate, rapidly mineralizing a large amount of solidified sludge in a short time, shortening the mineralization curing time of the solidified sludge, reducing the strong alkalinity of the solidified sludge, and neutralizing and adjusting the pH value of soil with low alkalinity;
step 7), pouring the solidified sludge with the water content less than or equal to 60% into a second mould (3), wherein a second through hole (3-1) is formed in the wall of a bottom mould plate of the second mould (3), then compacting the solidified sludge in the second mould (3) through a press machine (4), and the press machine (4) is provided with pressure rods (4-1) which are in one-to-one correspondence with the second through holes (3-1) by a press head, so that the extruded solidified sludge forms a porous sludge building block;
and 8) conveying a second die (3) provided with the porous sludge building blocks into the closed curing space (6), introducing industrial waste carbon dioxide gas, enabling the carbon dioxide gas to enter a porous structure inside the porous sludge building blocks through a second through hole (3-1), enabling steel slag around the porous structure to absorb the carbon dioxide gas to carry out carbonation reaction, generating stable calcium carbonate and magnesium carbonate, and improving the structural strength and compactness inside the solidified sludge.
2. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging substrate sludge according to claim 1, which is characterized in that: in the step 1), the solid waste materials comprise steel slag, slag and fly ash; the gel material comprises cement, limestone powder and bentonite.
3. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging substrate sludge according to claim 2, which is characterized in that: in the step 1), the curing agent comprises 65-75% of steel slag powder, 5-15% of fly ash, 5-10% of cement, 2-5% of limestone powder, 2-5% of bentonite and 0.1-1% of flocculant.
4. The method for mineralizing and maintaining carbon dioxide in river and lake dredging substrate sludge according to claim 3, wherein the method comprises the following steps of: in the step 1), the average grain diameter of the steel slag powder is 10-20 mu m, wherein SiO 2 The content is 5-10%, caO content is 50-70%, mgO content is 5-10%;
the activity index of the slag powder is more than S95, the average grain diameter is 1-100 mu m, and the specific surface area is more than 400m 2 /kg；
The national standard grade of the fly ash is more than grade II, the average grain diameter is 1-100 mu m, and the specific surface area is more than 300m 2 /kg；
The cement is Portland cement with the strength of more than or equal to 42.5 levels;
the limestone powder has average particle size of not more than 80nm, and CaCO 3 The content is more than 95 percent;
the bentonite has an average particle size of more than 38 mu m, wherein the montmorillonite component is more than 83%;
the flocculant consists of one or more of polyacrylamide, calcium acrylate and sodium polyacrylate, and the particle size is 50-200 mu m.
5. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging substrate sludge according to claim 1, which is characterized in that: in the step 3), the internal opening ratio of the first die (1) is 70-80%.
6. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging sediment, according to claim 5, is characterized in that: in the step 3), the first through hole (1-1) is a square hole with the size of 10 mm-20 mm.
7. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging substrate sludge according to claim 1, which is characterized in that: in the step 7), the aperture ratio of the bottom template wall of the second die (3) is 40-50%.
8. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging sediment, according to claim 7, is characterized in that: in the step 7), the layout mode of the second through holes (3-1) is that round holes with the size of 10 mm-12 mm are arranged at four corners, round holes with the size of 15 mm-20 mm are arranged at the middle positions, and square holes with the size of 10 mm-15 mm are arranged at the rest positions.
9. The method for mineralizing and maintaining the carbon dioxide in the river and lake dredging substrate sludge according to claim 1, which is characterized in that: in step 6) and step 8), the concentration of the carbon dioxide gas is more than 30%.
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