Method for preparing solid waste-based low-carbon concrete brick by utilizing industrial waste gas carbon mineralization

Abstract

The invention relates to a method for preparing a solid waste-based low-carbon concrete brick by utilizing industrial waste gas carbon mineralization. The method comprises the following steps: (1) weighing raw materials, namely weighing the following raw materials in parts by mass: 20-60 parts of Portland cement, 20-40 parts of concrete aggregate sieved waste, 20-40 parts of filter-pressed sludge and 10-15 parts of water; (2) green brick pressing: uniformly mixing the weighed solid material Portland cement, concrete aggregate sieved waste and filter-pressed sludge, adding water, uniformly mixing, and pressing into concrete green bricks; and (3) carbon mineralization maintenance: putting the prepared concrete green brick into a maintenance kettle, vacuumizing, and introducing industrial waste gas containing carbon dioxide gas to carry out carbon mineralization maintenance after a set vacuum degree is reached. The solid waste and industrial waste gas generated in the concrete production process are recycled, carbon emission in the production process can be greatly reduced, the production cost is reduced, and various properties of the prepared low-carbon concrete brick are equivalent to those of a common concrete brick.

Description

Technical Field

[0001] The invention relates to a method for preparing low-carbon concrete bricks based on solid wastes of building materials, and in particular to a method for preparing low-carbon concrete bricks based on solid wastes by utilizing carbon mineralization of industrial waste gas. Background Art

[0002] Protecting the ecological environment and achieving sustainable development have become urgent and arduous tasks facing the world. Construction waste is a major source of environmental pollution. With the continuous enhancement of environmental protection awareness and the implementation of the global strategy of sustainable development in the construction industry, it is crucial to develop new technologies for effective recycling and reuse of construction waste and industrial waste gas treatment.

[0003] With the acceleration of civil engineering construction, the demand for concrete has increased dramatically. In the process of producing concrete in factories, various types of solid waste are generated, such as aggregate screening waste (stone powder and sand powder produced after aggregate screening in concrete plants) and sludge produced after filter pressing (soil discharged from aggregate plants).

[0004] At present, domestic concrete plants do not have a way to properly handle or recycle these solid wastes. Aggregate screening waste and filter press sludge are randomly discarded around the concrete plant. These solid wastes will pollute the surrounding water sources, have a serious negative impact on the mixing plant and its surrounding environment, and cause a waste of resources.

[0005] On the other hand, the waste gas emitted by factories contains many harmful components such as carbon dioxide, carbon disulfide, hydrogen sulfide, fluoride, nitrogen oxides, chlorine, hydrogen chloride, carbon monoxide, etc. Discharging factory waste into the atmosphere will cause serious air pollution.

[0006] CN114804802A discloses a method for preparing carbonized bricks using industrial waste residues, which is characterized in that steel slag, tailings slag, fly ash and desulfurized gypsum are mixed and then dried, ball-milled, screened, formed, carbonized and cured to obtain carbonized bricks. However, the carbonized bricks do not contain aggregate components, which limits their scope of application.

[0007] CN114920538A discloses a concrete regenerated powder carbonized brick and a preparation method thereof, which is characterized in that carbon dioxide gas is introduced into a liquid storage tank to react with a solid waste solution to generate a calcium bicarbonate solution, the regenerated powder is filled into a molding mold, the calcium bicarbonate solution is decomposed by heat, and the generated carbon dioxide reacts with the calcium ions leached from the CSH gel in the regenerated powder to generate calcium carbonate, which is precipitated, crystallized and cemented in the mold together with the calcium carbonate generated by the decomposition of the calcium bicarbonate solution, and the regenerated powder generates strength. This method has many steps and is difficult to operate, and is difficult to implement in actual production.

[0008] The silicate cement and filler and the mineral components (dicalcium silicate C) in the water-cementing material for preparing concrete bricks 2 S, tricalcium silicate C 3 S), metal oxides (calcium oxide, magnesium oxide, aluminum oxide, etc.) and hydration products (calcium hydroxide Ca(OH) 2 Calcium silicate hydrate (CSH) and calcium silicate hydrate (CSH) are both calcium-rich alkaline substances that can react with carbon dioxide to form thermodynamically stable calcium carbonate and silica gel with volcanic ash activity. This carbonization treatment technology has been used by researchers for early maintenance of cement-based materials. 2 Curing concrete products can not only solidify CO 2 , reducing CO 2 It can also improve early strength, shorten curing time and cost, compact the surface structure of concrete, and reduce the permeability of concrete products. It is a green and economical CO 2 Capture, storage and utilization technologies.

[0009] However, the existing CO 2 The curing technology uses pure CO 2 There is no case of using industrial waste gas with low carbon dioxide concentration and high impurities for concrete brick maintenance. In addition, there is no case of using solid waste from concrete brick factories, such as aggregate screening waste and sludge after filter pressing, to prepare concrete bricks, which is not conducive to the development of concrete brick preparation towards the goal of low carbon emissions. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a method for preparing solid waste-based low-carbon concrete bricks by carbon mineralization of industrial waste gas, which uses solid waste generated in the process of preparing concrete raw materials such as sand and stone as the main raw material to prepare brick blanks, and uses industrial waste gas containing carbon dioxide to perform carbon mineralization and curing on the brick blanks.

[0011] The technical solution adopted by the present invention to solve the technical problem is a method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization, comprising the following steps:

[0012] (1) Weighing of raw materials: Weigh the following raw materials by weight: 20-60 parts of Portland cement, 20-40 parts of concrete aggregate sieve waste, 20-40 parts of sludge after filter pressing, and 10-15 parts of water;

[0013] (2) Brick pressing: the solid materials silicate cement, concrete aggregate sieve waste, and sludge after filter pressing weighed in step (1) are mixed evenly, water is added, and the mixture is pressed into concrete bricks by a brick making machine;

[0014] (3) Carbon mineralization curing: The concrete bricks prepared in step (2) are placed in a curing kettle, which is sealed and evacuated. After reaching a set vacuum degree, industrial waste gas containing carbon dioxide is introduced into the curing kettle for carbon mineralization curing, thereby obtaining a solid waste-based low-carbon concrete brick product.

[0015] Furthermore, in step (1), the concrete aggregate screening waste is stone powder and / or sand powder obtained in the aggregate screening process of the concrete plant.

[0016] Furthermore, in step (1), the concrete aggregate screening waste is stone powder and / or sand powder produced after aggregate screening in a concrete plant, and the particle size range is 0.15 mm to 4.75 mm.

[0017] Furthermore, in step (1), the sludge after filter pressing can be limestone or interlayer soil in the waste soil of a concrete plant.

[0018] Furthermore, in step (1), the sludge after filter pressing is not dried, and its water content is measured before raw material mixing. During the raw material mixing stage, the water content in the sludge after filter pressing is calculated as mixing water.

[0019] Further, in step (1), the CaO content in the sludge after filtration is ≥10%, and the Al 2 O 3 Content ≥2%.

[0020] Furthermore, in step (2), the concrete bricks are pressed and formed at a pressure ≥ 8 MPa.

[0021] Furthermore, in step (3), the vacuum degree is -0.1 to 0.5 MPa. After reaching the set vacuum degree, the vacuum degree is maintained for ≥ 0.5 hours, and then industrial waste gas containing carbon dioxide gas is introduced into the curing kettle for carbon mineralization curing.

[0022] Furthermore, the industrial waste gas is one or more of coal-fired power plant waste gas, cement kiln waste gas, and steel plant blast furnace tail gas.

[0023] Furthermore, the CO in the industrial waste gas 2 Volume concentration ≥3%.

[0024] Furthermore, the average temperature of the industrial waste gas is 20°C to 200°C.

[0025] Furthermore, the introduction rate of the industrial waste gas is 100ml / min to 1000ml / min.

[0026] Furthermore, the carbon mineralization curing pressure is 0.2-0.5 MPa.

[0027] Furthermore, the carbon mineralization curing time is ≥ 1 hour.

[0028] By utilizing the present invention, solid waste and industrial waste gas generated during the concrete production process can be recycled. Compared with conventional concrete brick preparation processes, carbon emissions during the production process and negative impacts on the environment can be greatly reduced, and the various properties of the solid waste-based low-carbon concrete bricks obtained are comparable to those of ordinary concrete bricks. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are further described in detail below in conjunction with examples.

[0030] The raw material parts in the following examples are all parts by mass.

[0031] Example 1

[0032] In this embodiment, the waste after concrete aggregate screening is collected as the aggregate of low-carbon concrete bricks, and the sludge after filter pressing is used as an auxiliary cementitious material to partially replace the cement clinker.

[0033] (1) Weigh 30 parts of concrete aggregate waste after sieving, 30 parts of sludge after filter pressing, 25 parts of Portland cement, and 15 parts of water;

[0034] (2) mixing the solid raw materials weighed in step (1) uniformly, and then pressing them into low-carbon concrete bricks at a pressure of 10 MPa using a brick-making machine;

[0035] (3) The pressed concrete bricks are placed in a curing kettle and sealed; the gas pressure in the curing kettle is reduced to -0.2 MPa using a vacuum device and the vacuum is maintained for 2 hours; the exhaust gas from the power plant is then introduced into the curing kettle through a connecting pipe, the volume concentration of carbon dioxide in the exhaust gas is 60%, the exhaust gas pressure in the curing kettle is 0.1 MPa, and the curing time is 8 hours to obtain low-carbon concrete bricks.

[0036] The waste-based low-carbon concrete bricks prepared by the industrial waste gas carbon mineralization were tested using the method in the industry standard JC-T422-2007 "Non-sintered waste tailings bricks" and the high-temperature muffle furnace calcination method. The compressive strength is 16.4MPa, the softening coefficient is 0.83, and the CO 2 Absorption capacity: 160kg / m 3 .

[0037] Example 2

[0038] In this embodiment, the waste after concrete aggregate screening is collected as the aggregate of low-carbon concrete bricks, and the sludge after filter pressing is used as an auxiliary cementitious material to partially replace the cement clinker.

[0039] (1) Weigh 30 parts of concrete aggregate waste after sieving, 30 parts of sludge after filter pressing, 25 parts of Portland cement, and 15 parts of water;

[0040] (2) The solid raw materials weighed in step (1) are mixed evenly, and then pressed into low-carbon concrete bricks at a pressure of 10 MPa by a brick-making machine.

[0041] (3) Place the pressed concrete bricks into a curing kettle and seal it. Use a vacuum device to reduce the gas pressure in the curing kettle to -0.2MPa and maintain the vacuum degree of 2 for two hours.

[0042] (4) The cement kiln tail gas is introduced into the curing kettle through a connecting pipe. The volume concentration of carbon dioxide in the tail gas is 15%. The waste gas pressure in the curing kettle is 0.1 MPa. The curing time is 24 hours, and low-carbon concrete bricks are obtained.

[0043] The waste-based low-carbon concrete bricks prepared by the industrial waste gas carbon mineralization were tested using the method in the industry standard JC-T422-2007 "Non-sintered waste tailings bricks" and the high-temperature muffle furnace calcination method. The compressive strength is 16.9MPa, the softening coefficient is 0.84, and the CO 2 Absorption capacity: 145kg / m 3 .

[0044] Example 3

[0045] In this embodiment, the waste after concrete aggregate screening is collected as the aggregate of low-carbon concrete bricks, and the sludge after filter pressing is used as an auxiliary cementitious material to partially replace the cement clinker.

[0046] (1) Weigh 25 parts of concrete aggregate waste after sieving, 25 parts of sludge after filter pressing, 40 parts of Portland cement, and 10 parts of water;

[0047] (2) mixing the solid raw materials weighed in step (1) uniformly, and then pressing them into low-carbon concrete bricks at a pressure of 10 MPa using a brick-making machine;

[0048] (3) The pressed concrete bricks are placed in a curing kettle and sealed. The gas pressure in the curing kettle is reduced to -0.2 MPa using a vacuum device and the vacuum is maintained for 2 hours. The waste gas from the power plant is then introduced into the curing kettle through a connecting pipe. The volume concentration of carbon dioxide in the waste gas is 60%. The waste gas pressure in the curing kettle is 0.1 MPa. The curing time is 8 hours, and low-carbon concrete bricks are obtained.

[0049] The waste-based low-carbon concrete bricks prepared by the industrial waste gas carbon mineralization were tested using the method in the industry standard JC-T422-2007 "Non-sintered waste tailings bricks" and the high-temperature muffle furnace calcination method. The compressive strength is 18.9MPa, the softening coefficient is 0.90, and the CO 2 Absorption capacity: 205kg / m 3 .

[0050] Example 4

[0051] In this embodiment, the waste after concrete aggregate screening is collected as the aggregate of low-carbon concrete bricks, and the sludge after filter pressing is used as an auxiliary cementitious material to partially replace the cement clinker.

[0052] (1) Weigh 25 parts of concrete aggregate waste after sieving, 25 parts of sludge after filter pressing, 40 parts of Portland cement, and 10 parts of water;

[0053] (2) mixing the solid raw materials weighed in step (1) uniformly, and then pressing them into low-carbon concrete bricks at a pressure of 10 MPa using a brick-making machine;

[0054] (3) The pressed concrete bricks are placed in a curing kettle and sealed. The gas pressure in the curing kettle is reduced to -0.2 MPa using a vacuum device and the vacuum is maintained for 2 hours. The cement kiln exhaust gas is then introduced into the curing kettle through a connecting pipe. The volume concentration of carbon dioxide in the exhaust gas is 15%. The exhaust gas pressure in the curing kettle is 0.1 MPa. The curing time is 24 hours to obtain low-carbon concrete bricks.

[0055] The waste-based low-carbon concrete bricks prepared by the industrial waste gas carbon mineralization were tested using the method in the industry standard JC-T422-2007 "Non-sintered waste tailings bricks" and the high-temperature muffle furnace calcination method. The compressive strength is 17.9MPa, the softening coefficient is 0.88, and the CO 2 Absorption capacity: 185kg / m 3 .

Claims

1. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization. It is characterized in that: The following steps are involved: (1) Weighing of raw materials: Weigh the following raw materials by weight: 20-60 parts of Portland cement, 20-40 parts of concrete aggregate sieve waste, 20-40 parts of sludge after filter pressing, and 10-15 parts of water; (2) Brick pressing: the solid materials silicate cement, concrete aggregate sieve waste, and sludge after filter pressing weighed in step (1) are mixed evenly, water is added, and the mixture is pressed into concrete bricks by a brick making machine; (3) Carbon mineralization curing: The concrete bricks prepared in step (2) are placed in a curing kettle, which is sealed and evacuated. After reaching a set vacuum degree, industrial waste gas containing carbon dioxide is introduced into the curing kettle for carbon mineralization curing, thereby obtaining a solid waste-based low-carbon concrete brick product.

2. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to claim 1. Characterized in that: In step (1), the concrete aggregate screening waste is stone powder and / or sand powder obtained in the aggregate screening process of the concrete plant.

3. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to claim 1, characterized in that: In step (1), the concrete aggregate screening waste is stone powder and / or sand powder produced after aggregate screening in a concrete plant, and the particle size range is 0.15 mm to 4.75 mm.

4. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to claim 1, characterized in that: In step (1), the sludge after filter pressing is limestone or interlayer soil in the waste soil of the concrete plant.

5. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to any one of claims 1 to 4, characterized in that: In step (1), the CaO content in the sludge after filtration is ≥10%, and the Al2O3 content is ≥2%.

6. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to any one of claims 1 to 4, characterized in that: In step (2), the concrete bricks are pressed and formed at a pressure ≥ 8 MPa.

7. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to any one of claims 1 to 4, characterized in that: In step (3), the vacuum degree is -0.1 to 0.5 MPa. After reaching the set vacuum degree, the vacuum degree is maintained for ≥ 0.5 hours, and then industrial waste gas containing carbon dioxide gas is introduced into the curing kettle for carbon mineralization curing.

8. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to any one of claims 1 to 4, characterized in that: In step (3), the industrial waste gas is one or more of coal-fired power plant waste gas, cement kiln waste gas, and steel plant blast furnace tail gas; the CO2 volume concentration in the industrial waste gas is ≥3%.

9. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to any one of claims 1 to 4, characterized in that: In step (1), the average temperature of the industrial waste gas is 20°C to 200°C.

10. A method for preparing solid waste-based low-carbon concrete bricks by utilizing industrial waste gas carbon mineralization according to any one of claims 1 to 4, characterized in that: In step (3), the introduction rate of the industrial waste gas is 100 ml / min to 1000 ml / min; the pressure of the carbon mineralization curing is 0.2 to 0.5 MPa; and the time of the carbon mineralization curing is ≥ 1 hour.