Device and method for preparing negative carbon cementing material by wind power suspension semi-dry method

Abstract

The invention discloses a device and a method for preparing a negative carbon cementing material by a wind power suspension semi-dry method, and belongs to the technical field of comprehensive utilization of solid waste resources. The method for preparing the negative carbon cementing material comprises the following steps: keeping the humidity and CO2 concentration of a reaction system, and carbonizing the wet steel slag micro-powder in the reaction system while the wet steel slag micro-powder is in a suspended state under the action of wind power, so as to obtain the negative carbon cementing material. The CO2 storage rate of the prepared negative carbon cementing material is equivalent to that of wet carbonization, the CO2 storage rate of the negative carbon cementing material is 8-12%, and the bulk density is 1.05-1.2 g / cm < 3 >. In the preparation process, the water resource consumption is extremely low, no wastewater is discharged, and water resource waste and wastewater discharge pollution are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of solid waste resources, and particularly to an apparatus and method for preparing a negative-carbon cementitious material by a wind suspension semi-dry method. Background Art

[0002] Steel slag is a large amount of solid waste generated during the steel smelting process. The large accumulation of steel slag seriously wastes land resources and pollutes the environment. Incorporating a certain amount of steel slag as an auxiliary cementitious material to replace part of the cement in concrete can not only effectively utilize steel slag, but also will not significantly reduce the strength of concrete. It is an effective way to reduce the cement consumption and dispose of steel slag solid waste at present. However, steel slag is rich in free calcium oxide and magnesium oxide, resulting in prominent volume stability problems. Directly incorporating it into concrete is likely to cause building structure safety. In recent years, research has shown that steel slag has strong carbonation activity, that is, the calcium and magnesium minerals in steel slag can rapidly react with CO2, generating a large amount of nano-scale carbonates while consuming free calcium oxide and magnesium oxide, and can also sequester a large amount of CO2, avoiding the volume stability problems caused by free calcium oxide and magnesium oxide.

[0003] The current method for preparing carbonated steel slag auxiliary cementitious material is mainly wet carbonation, that is, passing CO2 into an aqueous solution to react with calcium and magnesium ions to form carbonates. This method can not only strengthen the aggregate by using the carbonates generated by carbonation, but also prepare calcium carbonate with high added value. However, wet carbonation requires a large amount of water resources. Data shows that the wet carbonation method usually requires tap water equivalent to 10-20 times the mass of steel slag to promote the rapid leaching and carbonation of Ca 2+ ions. And the wastewater containing heavy metals and other pollutants generated may also cause secondary environmental pollution.

[0004] Therefore, it is urgent to develop a new carbonation method to prepare steel slag-based negative-carbon auxiliary cementitious material to reduce water resource consumption and reduce the risk of environmental pollution caused by wastewater discharge. Summary of the Invention

[0005] The purpose of the present invention is to provide an apparatus and method for preparing a negative-carbon cementitious material by a wind suspension semi-dry method to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: A method for preparing a negative-carbon cementitious material, comprising the following steps:

[0008] Maintain the humidity and CO2 concentration of the reaction system, and carbonize the wet steel slag fine powder in the reaction system while keeping it in a suspended state by the action of wind to obtain the negative-carbon cementitious material;

[0009] The humidity is 60-80%, and the CO2 concentration is 10-20 vol.%.

[0010] The second technical solution of the present invention: A negative carbon cementitious material prepared by the above method.

[0011] The third technical solution of the present invention: An application of the above negative carbon cementitious material in the preparation of concrete.

[0012] The fourth technical solution of the present invention: A wind suspension semi-dry method device for realizing the above method for preparing a negative carbon cementitious material, the wind suspension semi-dry method device consists of a box body with air permeable holes on the top and bottom surfaces and a fan;

[0013] The fan is placed at the bottom of the box body.

[0014] The fifth technical solution of the present invention: A method for preparing a negative carbon cementitious material by using the above wind suspension semi-dry method device, comprising the following steps:

[0015] Place the wet steel slag micro-powder on the bottom surface of the box body, then place the wind suspension semi-dry method device in a carbon curing box, maintain the humidity and CO2 concentration in the carbon curing box, turn on the fan, and carbonize the wet steel slag micro-powder while keeping it in a suspended state by the action of wind to obtain the negative carbon cementitious material;

[0016] The humidity in the box body is 60-80%, and the CO2 concentration is 10-20 vol.%.

[0017] Further, the dosage ratio of water to steel slag micro-powder in the wet steel slag micro-powder is 1 mL: 10 g;

[0018] The particle size of the steel slag micro-powder is less than 150 μm.

[0019] Further, the top surface of the box body is a sieve mesh with a pore size of 300 meshes, and the bottom surface is a sieve mesh with a pore size of 200 meshes.

[0020] Further, the temperature of carbonization is 20 °C, and the time is 0.5-1 h;

[0021] The air volume of the wind action is 100-300 m 3 / h.

[0022] The bulk density of the negative carbon cementitious material is 1.05-1.2 g / cm 3 , and the CO2 sequestration rate is 8-12%.

[0023] The present invention uses steelmaking industrial solid waste (steel slag micro-powder) as a raw material, continuously inputs a mixed gas rich in moisture and CO2 through a fan, promotes the rapid carbonization of steel slag, and realizes zero wastewater discharge.

[0024] Mechanism of the carbonation of steel slag powder: Water is an important medium for the carbonation of steel slag powder, and the entire carbonation reaction is mainly achieved in liquid water. Part of the calcium in the solid-phase steel slag powder dissolves in the liquid water to form Ca 2+ , and the gaseous CO2 also dissolves in the liquid water to form CO3 2- ; then Ca 2+ combines with CO3 2- to form calcium carbonate precipitate. Through this process, the free calcium oxide and magnesium oxide in the steel slag powder are consumed, CO2 is captured and solidified, and nano-scale carbonates are formed.

[0025] Mechanism of the rapid carbonation by the wind-levitated semi-dry method: On the one hand, a higher wind speed promotes the steel slag powder to be in a suspended state, avoiding the agglomeration and cementation of the steel slag powder and increasing the exposed area of the steel slag powder; on the other hand, a higher wind speed promotes the rapid input and infiltration of the mixed gas rich in moisture and CO2 into the steel slag powder, increasing the contact and reaction efficiency between the steel slag powder and CO2. Therefore, even if the water-solid ratio of the wind-levitated semi-dry carbonation is extremely low, a relatively fast carbonation reaction rate and carbonation level can still be achieved.

[0026] The present invention discloses the following technical effects:

[0027] (1) The CO2 sequestration rate of the negative carbon cementitious material prepared by the present invention is comparable to that of the wet carbonation, and its CO2 sequestration rate is 8-12% (that is, 0.08-0.12 kg of CO2 is sequestered per kg of steel slag powder), and the bulk density is 1.05-1.2 g / cm 3 , and this method is simple and easy to implement, can achieve high-efficiency CO2 fixation (low carbon emissions) and zero wastewater discharge, and provides an intensive and sustainable method for consuming a large amount of solid waste.

[0028] (2) The wind-levitated semi-dry device of the present invention adjusts the wind speed to promote and maintain the steel slag powder in a suspended state, improves the contact and reaction efficiency between moisture, CO2 and the steel slag powder, and significantly increases the carbonation reaction rate of the steel slag.

[0029] (3) In the preparation process of the present invention, the water consumption is extremely low and there is no wastewater discharge, avoiding water resource waste and wastewater discharge pollution.

[0030] (4) The method of the present invention can keep the steel slag powder in a suspended state during the carbonation process, ensuring that the steel slag powder is still loose and independent particles after carbonation and does not need to be ground again, saving the grinding energy consumption. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0032] Figure 1 Figure 1 is a schematic diagram of the wind-levitated semi-dry method device and its operation adopted in Embodiment 1 of the present invention. Among them, 1 is a fan (lower fan), 2 is a 200-mesh sieve, 3 is steel slag micro-powder (levitated micro-powder), 4 is an acrylic tube, 5 is a 300-mesh sieve, 6 is a carbonization curing box, 7 is a CO2 flowmeter, and 8 is a CO2 gas cylinder;

[0033] Figure 2 Figure 2 is a physical diagram of the negative-carbon cementitious material (carbonized steel slag) prepared in Embodiment 1 and a micrograph of the calcite-type calcium carbonate formed in the negative-carbon cementitious material. Detailed Embodiments

[0034] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0035] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0036] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0037] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of the present invention are merely exemplary.

[0038] As used herein, terms such as "comprising", "including", "having", "containing", etc. are all open-ended terms, meaning including but not limited to.

[0039] All "parts" mentioned in the following examples are "parts by weight".

[0040] The wind suspension semi-dry method device adopted in the specific implementation manner of the present invention is composed of a lower-layer screen, an upper-layer screen, an acrylic tube and a fan;

[0041] The lower-layer screen is placed at the lower end of the acrylic tube, and the upper-layer screen is placed at the upper end of the acrylic tube, and is connected to the acrylic tube to form a chamber for placing steel slag fine powder (particle size less than 150 μm);

[0042] The fan is placed at the bottom of the acrylic tube and is connected to the lower-layer screen. Through the wind force of the fan, the delivery amounts of moisture and CO2 are regulated, and the steel slag fine powder is maintained in a suspended state; at the same time, through the action of the fan, CO2 and moisture can be quickly input, which can effectively increase the contact efficiency between the mixed gas and the steel slag fine powder, and thus improve the carbonization efficiency of the steel slag fine powder;

[0043] The aperture of the lower-layer screen is 200 mesh, which is conducive to the rapid entry of moisture and CO2; the aperture of the upper-layer screen is 300 mesh, which is conducive to the flow of gas, and at the same time avoids the leakage of steel slag fine powder and dust pollution.

[0044] The carbonization curing box adopted in the specific implementation manner of the present invention is connected to a CO2 gas cylinder through a pipeline, and a CO2 flowmeter is arranged on the pipeline.

[0045] Example 1

[0046] A method for preparing a negative-carbon cementitious material by using the wind suspension semi-dry method:

[0047] (1) Take a screen 2 with an aperture of 200 mesh, place it at the lower end of the acrylic tube 4 (the diameter of the acrylic tube 4 is 5 cm) and connect it to the acrylic tube. Evenly spread the wet converter steel slag fine powder (suspended fine powder) 3 on the screen 2 (the volume of the wet steel slag fine powder does not exceed 1 / 3 of the volume of the acrylic tube). Take a screen 5 with an aperture of 300 mesh and place it at the upper end of the acrylic tube and connect it to the acrylic tube to form a chamber for placing steel slag fine powder;

[0048] Among them, the steel slag fine powder is converter steel slag fine powder with a particle size less than 75 μm, and the chemical composition is shown in Table 1.

[0049] Table 1 Chemical composition of converter steel slag fine powder (wt.%)

[0050] Component CaO <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> MgO Others Content 44.9 20.1 15.7 3.8 15.5

[0051] Mix water with steel slag powder at a water-solid ratio of 1 mL:10 g and moisten to obtain moist steel slag powder.

[0052] (2) Place the blower 1 at the bottom of the acrylic tube 4 and connect it to the sieve 2;

[0053] Among them, the blower 1, the sieve 2, the acrylic tube 4, and the sieve 5 form a wind suspension semi-dry method device.

[0054] (3) Place the wind suspension semi-dry method device containing the moist steel slag powder in a carbonation curing box 6 that has been pre-adjusted to a relative humidity of 80%, a CO2 concentration of 20 vol.%, and a temperature of 20 °C.

[0055] Among them, the carbonation curing box 6 is connected to a CO2 gas cylinder through a pipeline, and a CO2 flow meter 7 is provided on the pipeline to adjust the CO2 concentration.

[0056] (4) Turn on the blower 1 and adjust the air volume to 100 m 3 / h. After carbonation for 1 h, turn off the blower 1 and the carbonation curing box 6, and take out the carbonated steel slag powder, which is the negative carbon cementitious material prepared by the wind suspension semi-dry method.

[0057] The wind suspension semi-dry method device and the operation schematic diagram used in this example are shown in Figure 1 .

[0058] The physical picture of the negative carbon cementitious material (carbonated steel slag) prepared in this example and the microscopic morphology picture of calcite-type calcium carbonate formed in the negative carbon cementitious material are shown in Figure 2 .

[0059] The bulk density of the negative carbon cementitious material prepared in this example is 1.07 g / cm 3 , and the CO2 sequestration rate is 11.39%.

[0060] Comparative Example 1

[0061] Prepare negative carbon cementitious material by the wet carbonation method:

[0062] Mix 1 kg of converter steel slag powder (the same as the steel slag powder in step (1) of Example 1) with 20 kg of water to prepare a suspension, and under the environment of 20 °C, introduce CO2 gas with a concentration of 20 vol.% at a flow rate of 3 L / min. After carbonation for 1 h, filter and dry to obtain the negative carbon cementitious material (carbonated steel slag powder).

[0063] Compare the water consumption, carbonation cycle and carbonation efficiency of the negative carbon cementitious material preparation methods of Example 1 and Comparative Example 1 in Table 2.

[0064] Table 2 Water consumption, carbonation cycle and carbonation efficiency of different carbonation methods

[0065]

[0066] As can be seen from Table 2, the water consumption of the wind-force suspension semi-dry method is only 1 / 200 of that of the wet carbonization method, and when the carbonization periods are comparable, the CO2 sequestration rate reaches 85.3% of that of the wet carbonization method.

[0067] Example 2

[0068] Same as Example 1, the difference is only that the steel slag powder used in step (1) is the electric furnace steel slag powder with a particle size less than 75 μm, and the chemical composition is shown in Table 3.

[0069] Table 3 Chemical composition of the electric furnace steel slag powder (wt.%)

[0070] Component CaO <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> MgO Others Content 34.28 29.79 18.63 3.0 14.3

[0071] The bulk density of the negative-carbon cementitious material prepared in this example is 1.18 g / cm 3 , and the CO2 sequestration rate is 8.7%.

[0072] Comparative Example 2

[0073] Prepare the negative-carbon cementitious material by using the wet carbonization method:

[0074] Mix 1 kg of electric furnace steel slag powder (the same as the steel slag powder in step (1) of Example 2) with 20 kg of water to prepare a suspension, and under the environment of 20 °C, introduce CO2 gas with a concentration of 20 vol.% at a flow rate of 3 L / min. After carbonization for 1 h, filter and dry to obtain the negative-carbon cementitious material (carbonized steel slag powder).

[0075] The comparison of the water consumption, carbonization period and carbonization efficiency of the preparation of the negative-carbon cementitious material by using the methods of Example 2 and Comparative Example 2 is shown in Table 4.

[0076] Table 4 Water consumption, carbonization period and carbonization efficiency of different carbonization methods

[0077]

[0078] As can be seen from Table 4, the water consumption of the wind-force suspension semi-dry method is only 1 / 200 of that of the wet method, and when the carbonization periods are comparable, the CO2 sequestration rate reaches 85.2% of that of the wet carbonization method.

[0079] The test results of Examples 1-2 and Comparative Examples 1-2 all show that: the water consumption of the wind-force suspension semi-dry method is much lower than that of the wet carbonization method, and when the carbonization periods are the same, the CO2 sequestration rate exceeds 85% of that of the wet carbonization method.

[0080] Comparative Example 3

[0081] In the comparative experiment, the mesh number of the sieve was mainly changed to explore its influence on the process of preparing the negative-carbon cementitious material by the wind suspension semi-dry method, while keeping other conditions the same as those in Example 1.

[0082] The specific operation is as follows:

[0083] Take a sieve 2 with a pore size of 100 meshes and place it at the lower end of the acrylic tube 4 (the diameter of the acrylic tube 4 is 5 cm) and connect it to the acrylic tube. Spread the wet converter steel slag fine powder (suspended fine powder) 3 evenly on the sieve 2 (the volume of the wet steel slag fine powder does not exceed 1 / 3 of the volume of the acrylic tube). Take a sieve 5 with a pore size of 200 meshes and place it at the upper end of the acrylic tube and connect it to the acrylic tube to form a chamber for placing the steel slag fine powder.

[0084] Comparative Example 4

[0085] In the comparative experiment, the mesh number of the sieve was mainly changed to explore its influence on the process of preparing the negative-carbon cementitious material by the wind suspension semi-dry method, while keeping other conditions the same as those in Example 1.

[0086] The specific operation is as follows:

[0087] Take a sieve 2 with a pore size of 300 meshes and place it at the lower end of the acrylic tube 4 (the diameter of the acrylic tube 4 is 5 cm) and connect it to the acrylic tube. Spread the wet converter steel slag fine powder (suspended fine powder) 3 evenly on the sieve 2 (the volume of the wet steel slag fine powder does not exceed 1 / 3 of the volume of the acrylic tube). Take a sieve 5 with a pore size of 400 meshes and place it at the upper end of the acrylic tube and connect it to the acrylic tube to form a chamber for placing the steel slag fine powder.

[0088] The experimental results of Comparative Example 3 and Comparative Example 4 show that when the mesh number of the sieve increases (the sieve pore diameter decreases), due to the decrease in the actual ventilation volume, the CO2 sequestration rate of the steel slag fine powder carbonized for 1 h also decreases to 10.14%. When the mesh number of the sieve decreases (the sieve pore diameter increases), the steel slag fine powder is easily blown out of the device, resulting in a loss of about 6% of the material during the carbonization process, reducing the quality and output of the final product. It shows that the mesh number of the sieve has a significant influence on the process of preparing the negative-carbon cementitious material by the wind suspension semi-dry method.

[0089] Effect Example 1

[0090] The method for preparing concrete by using the negative-carbon cementitious material provided by the present invention:

[0091] (1) The raw materials are prepared as follows:

[0092] Carbonized steel slag: The carbonized steel slag obtained by wet carbonization treatment (prepared in Comparative Example 1).

[0093] Carbonized steel slag: The carbonized steel slag obtained by wind suspension carbonization treatment (prepared in Example 1).

[0094] Uncarbonized steel slag: Steel slag that has not been carbonized (the converter steel slag powder in Example 1).

[0095] (2) The specific steps for preparing the concrete are as follows:

[0096] Step 1: Weigh 15 wt% of the carbonized steel slag obtained by wet carbonization treatment, 15 wt% of the carbonized steel slag obtained by wind suspension carbonization treatment, or 15 wt% of the uncarbonized steel slag, and mix them evenly with 85% cement.

[0097] Step 2: Mix the mixed cementitious materials with water at a water-cement ratio of 0.35 and stir evenly.

[0098] Step 3: Pour the mixed concrete into a mold, carry out standard curing, and measure the properties of the concrete. The results are shown in Table 5.

[0099] Table 5 Properties of different concretes

[0100]

[0101] From the above results, it can be seen that the wind suspension carbonized steel slag provided by the present invention improves the compressive strength of the concrete compared with the traditional wet carbonized steel slag and directly incorporated uncarbonized steel slag, and has high application value.

[0102] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a negative carbon gelling material, characterized in that: The following steps are involved: The humidity and CO2 concentration of the reaction system are maintained, and the wet steel slag powder in the reaction system is suspended and carbonized by wind to obtain the negative carbon cementitious material; The humidity is 60-80%, and the CO2 concentration is 10-20 vol.%.

2. A negative carbon gelled material prepared by the method according to claim 1.

3. Use of the negative carbon cementitious material according to claim 2 in the preparation of concrete.

4. A wind-driven semi-dry suspension device for implementing the method for preparing negative carbon cementitious materials according to claim 1, characterized in that: The wind-powered suspension semi-dry method device is composed of a box body with air holes on the top and bottom surfaces and a fan; The fan is placed at the bottom of the box.

5. A method for preparing negative carbon cementitious materials using the wind-powered suspension semi-dry method device according to claim 4, characterized in that: The following steps are involved: The wet steel slag powder is placed on the bottom surface of the box, and then the wind suspension semi-dry method device is placed in the carbon curing box, the humidity and CO2 concentration in the carbon curing box are maintained, and the fan is turned on to suspend the wet steel slag powder and carbonize it by wind to obtain the negative carbon cementitious material; The humidity in the box is 60-80%, and the CO2 concentration is 10-20 vol.%.

6. The method according to claim 5, characterized in that The ratio of water to steel slag powder in the wet steel slag powder is 1 mL:10 g; the particle size of the steel slag powder is less than 150 μm.

7. The method according to claim 5, characterized in that The top surface of the box is a sieve with an aperture of 300 meshes, and the bottom surface is a sieve with an aperture of 200 meshes.

8. The method according to claim 5, characterized in that The carbonization temperature is 20°C and the time is 0.5 to 1 hour; the wind volume is 100 to 300 m 3 / h.

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