A slurry composition for bricks / block and a process for its preparation

Abstract

The present application provides a kind of brick / block slurry composition and the process for preparing brick / block, which is prepared by the following raw materials: fly ash 62-70 parts by weight, cement 7-15 parts by weight, desulfurization wastewater 20-23 parts by weight, wherein the sodium ion content in the desulfurization wastewater is not more than 5000 mg / L, and the chloride ion content is not more than 15000 mg / L.The present application uses desulfurization wastewater generated by coal-fired power plants and fly ash as raw materials, uses ordinary cementitious materials, and through solid-liquid interface coupling and fly ash activation solidification reaction, a kind of brick / block that can meet the building materials industry standard is prepared, realizing the purpose of waste treatment.

Description

Technical Field

[0001] This invention belongs to the technical field of building materials, and in particular relates to a mortar composition for bricks / blocks and a process for preparing bricks / blocks. Background Technology

[0002] To meet national requirements for sulfur dioxide emissions from flue gas, coal-fired power plants must reduce their emissions to below 35 mg / m³. 3 Most desulfurization processes use wet methods, resulting in desulfurization gypsum and desulfurization wastewater. The main ionic components of the desulfurization wastewater include sodium (Na₂O₃). + Cl - SO4 2- Currently, after water treatment, desulfurization wastewater that does not meet emission standards is treated in three ways: 1) Mixing with fly ash to reduce dust during transportation, and finally landfilling, but this increases landfill costs due to the added weight; 2) Treating flue gas desulfurization wastewater, which may increase the chloride ion and other heavy metal content in fly ash, reducing the utilization of fly ash resources, especially in cement and concrete applications; 3) Evaporation or crystallization water treatment technology, which is the safest and most reliable but also the most expensive, producing a small amount of high-salt water or concentrated liquid.

[0003] Currently, there is not much research on the application of fly ash in treating desulfurization wastewater both domestically and internationally. On December 18, 2020, a literature search using CNKI with fly ash as the abstract and desulfurization wastewater as the keyword yielded 38 relevant articles. These articles mainly focus on the treatment of ions or heavy metals in wastewater. Among them are studies that are similar to the project's technical approach, such as solidifying chloride ions in desulfurization wastewater with cement and fly ash and preparing products, with applications in chloride-free corrosion prevention.

[0004] However, there is currently no relevant technology that aims to couple the preparation of bricks / blocks with the minimum cement usage, the maximum fly ash usage, and desulfurization wastewater. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a brick / block that meets the standards of the building materials industry by using fly ash and desulfurization wastewater as raw materials and ordinary cementing materials (such as cement) through solid-liquid interface coupling and fly ash-induced solidification reaction, thereby achieving the purpose of treating waste (desulfurization wastewater) with waste (fly ash).

[0006] To achieve the objectives of this invention, the following technical solution is adopted:

[0007] The present invention provides a mortar composition for bricks / blocks in a first aspect, the mortar composition being prepared from the following raw materials: 62-70 parts by weight of fly ash, 7-15 parts by weight of cement, and 20-23 parts by weight of desulfurization wastewater, based on the weight parts of the raw materials; wherein the sodium ion content in the desulfurization wastewater does not exceed 5000 mg / L and the chloride ion content does not exceed 15000 mg / L.

[0008] In the brick / block mortar composition provided by the present invention, by controlling the sodium ion content in the desulfurization wastewater to not exceed 5000 mg / L and the chloride ion content to not exceed 15000 mg / L, the compressive strength of the composition can be fully increased during the mixing and stirring process with cement and fly ash, thereby further improving the compressive strength of the obtained fly ash bricks / blocks.

[0009] In some specific embodiments, the total weight of the raw materials in the slurry composition is 100 parts by weight, including 62-70 parts by weight of fly ash, 7-15 parts by weight of cement, and 20-23 parts by weight of desulfurization wastewater; for example, in the raw material composition of the slurry composition, fly ash is 65 parts by weight, cement is 12 parts by weight, and desulfurization wastewater is 23 parts by weight.

[0010] In some preferred embodiments of the slurry composition, the sodium ion content in the desulfurization wastewater is 700–3000 mg / L, for example, 1000 mg / L, 2000 mg / L, or 2500 mg / L; and the chloride ion content is 3000–14200 mg / L, for example, 4000 mg / L, 5000 mg / L, 6000 mg / L, 7000 mg / L, 8000 mg / L, 9000 mg / L, 10000 mg / L, or 13000 mg / L.

[0011] In the slurry composition provided in this invention, the desulfurization wastewater originates from the raw or effluent of desulfurization wastewater generated by flue gas desulfurization in a coal-fired power plant. This desulfurization wastewater further includes the following components: calcium ion content of 700–3000 mg / L, for example, 1000 mg / L, 1500 mg / L, 2000 mg / L, or 2500 mg / L; and magnesium ion content of 2500–16000 mg / L, for example, 3000 mg / L, 4000 mg / L, 5000 mg / L, 6000 mg / L, 7000 mg / L, or 8000 mg / L. mg / L, 10000mg / L, 15000mg / L; potassium ion content is 20-130mg / L, for example, 50mg / L, 80mg / L, 100mg / L, 120mg / L; sulfate ion content is 9000-58000mg / L, for example, 10000mg / L, 15000mg / L, 20000mg / L, 25000mg / L, 30000mg / L, 35000mg / L, 40000mg / L, 45000mg / L, 50000mg / L.

[0012] In some specific embodiments, based on the total weight parts of the raw materials in the slurry composition, fly ash is 65 to 68 parts by weight, for example, 66 parts by weight or 67 parts by weight; cement is 10 to 13 parts by weight, for example, 11 parts by weight or 12 parts by weight; and desulfurization wastewater is 21 to 22 parts by weight, for example, 21.5 parts by weight.

[0013] The fly ash used in this invention has an average particle size (D50) of 2–25 μm, preferably 6–15 μm. 10 Less than 2μm, D 50 Less than 13μm, D 90 Less than 60μm.

[0014] In some specific embodiments, the cement used in this invention may be selected from ordinary silicate cement PO 42.5R.

[0015] In a second aspect, the present invention provides a method for preparing bricks / blocks using the above-described slurry composition, comprising:

[0016] S1. Mix fly ash and cement and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material;

[0017] S2. The mixed dry material is added to the desulfurization wastewater and mixed and stirred to obtain a slurry;

[0018] S3. Pour the slurry into a triple mold to form and cure it to obtain bricks / blocks.

[0019] In step S2 of the specific preparation method, the water-to-material ratio of the desulfurization wastewater to the mixed dry material is 0.21–0.23, for example, 0.22. In some specific embodiments, the mixed dry material is added to the desulfurization wastewater and stirred. Specifically, the mixture can be placed in a stirring apparatus, and an automatic program (60s slow stirring, 60s fast stirring, 60s intermittent stirring, 60s fast stirring) can be started for stirring until the fluidity of the material reaches 190–193 mm, at which point the stirring process is completed, and a slurry is obtained. By controlling the fluidity of the material, both the operability of the slurry and the water consumption can be controlled to improve the strength.

[0020] In the specific preparation method S3, curing is carried out at a temperature of 21-25°C and a humidity of over 90%.

[0021] The above technical solution achieves the following technical effects:

[0022] This invention uses desulfurization wastewater (raw water or effluent) and fly ash from coal-fired power plants as raw materials, and controls the sodium and chloride ion content in the wastewater (sodium ion content not exceeding 5000 mg / L and chloride ion content not exceeding 15000 mg / L). This allows the addition of a relatively small amount of cementitious material (such as cement) to couple at the solid-liquid interface, achieving a fly ash-induced solidification reaction. The resulting fly ash bricks achieve ion solidification and meet the performance requirements of building materials industry standard JC 239-2001, while the resulting fly ash blocks meet the ion solidification effect and the performance requirements of building materials industry standard JC238-1996. This invention achieves the technological innovation effect of treating waste (desulfurization wastewater) with waste (fly ash), turning both wastes into resources. Detailed Implementation

[0023] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0026] The following examples demonstrate the use of the following methods to test the performance indicators of bricks / blocks:

[0027] (1) Average compressive strength at 7 days / 28 days and average flexural strength at 7 days / 28 days: Tested according to the methods specified in GB / T17671 "Test Method for Strength of Cement Mortar";

[0028] (2) Flowability: Tested according to the method specified in GB / T2419.

[0029] The following examples use device information:

[0030] (1) Mixer: JJ-5 type, Wuxi Jianyi Instrument Machinery Co., Ltd.;

[0031] (2) Standard curing box for cement concrete: Model HBY-40A, effective volume 0.4m³ 3 65×50×130cm, Wuxi Jianyi Instrument Machinery Co., Ltd.;

[0032] (3) Compressive and flexural testing equipment: TYE-300D cement mortar flexural and compressive testing machine, Wuxi Jianyi Instrument Machinery Co., Ltd.;

[0033] Raw material information in the following examples and comparative examples:

[0034] Fly ash: Fly ash (coarse ash) from the second phase of Yuanyanghu Power Plant, with an average particle size D50 of 2-25 μm;

[0035] Desulfurization wastewater: raw desulfurization wastewater from the second phase of Yuanyanghu Power Plant;

[0036] Cement: Ordinary Portland cement PO 42.5R, purchased by Ningxia Building Materials Group.

[0037] Example 1

[0038] The specific composition of the desulfurization wastewater used in this embodiment is shown in Table 1;

[0039] Table 1

[0040]

[0041] S1. Weigh 180g of cement and 820g of fly ash, mix them and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material;

[0042] S2. Weigh 210g of the above desulfurization wastewater (water-to-material ratio of 0.21) and pour it into the mixing pot. Then add the weighed mixed dry material into the mixing pot, place it on the mixing instrument, and start the automatic program (60s slow stirring, 60s fast stirring, 60s intermittent stirring, 60s fast stirring) to mix and stir to obtain a slurry.

[0043] S3. Place the mixed material slurry into the slurry mold and test its flowability. The flowability is 190 mm, and the mixing is complete. Pour it into a sample triple mold and wrap the mold with plastic wrap. Place it in a standard cement concrete curing chamber with a temperature of 20±2℃ and a humidity of over 90% for curing. Test its compressive and flexural strength after 7 days and 28 days of curing.

[0044] Example 2

[0045] The specific composition of the desulfurization wastewater used in this embodiment is shown in Table 2;

[0046] Table 2

[0047]

[0048] S1. Weigh 180g of cement and 820g of fly ash, mix them and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material;

[0049] S2. Weigh 220g of the above desulfurization wastewater (water-cement ratio of 0.22) and pour it into the mixing pot. Then add the weighed mixed dry material into the mixing pot, place it on the mixing instrument, and start the automatic program (60s slow stirring, 60s fast stirring, 60s intermittent stirring, 60s fast stirring) to mix and obtain a slurry.

[0050] S3. Place the mixed material slurry into the slurry mold and test its flowability. The flowability is 192 mm, and the mixing is complete. Pour it into a sample triple mold and wrap the mold with plastic wrap. Place it in a standard cement concrete curing chamber with a temperature of 20±2℃ and a humidity of over 90% for curing. Test its compressive and flexural strength after 7 days and 28 days of curing.

[0051] Example 3

[0052] The specific composition of the components in the desulfurization wastewater used in the examples is shown in Table 3;

[0053] Table 3

[0054]

[0055] S1. Weigh 100g of cement and 900g of fly ash, mix them and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material;

[0056] S2. Weigh 230g of the above desulfurization wastewater (water-cement ratio of 0.23) and pour it into the mixing pot. Then add the weighed mixed dry material into the mixing pot, place it on the mixing instrument, and start the automatic program (60s slow stirring, 60s fast stirring, 60s intermittent stirring, 60s fast stirring) to mix and obtain a slurry.

[0057] S3. Place the mixed material slurry into the slurry mold and test its flowability. The flowability is 193 mm, and the mixing is complete. Pour it into a sample triple mold and wrap the mold with plastic wrap. Place it in a standard cement concrete curing chamber with a temperature of 20±2℃ and a humidity of over 90% for curing. Test its compressive and flexural strength after 7 days and 28 days of curing.

[0058] Comparative Example 1

[0059] This comparative example uses desulfurization wastewater with the same composition as in Example 1.

[0060] S1. Weigh 50g of cement and 950g of fly ash, mix them and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material;

[0061] S2. Weigh 220g of desulfurization wastewater (water-cement ratio of 0.22) and pour it into the mixing pot. Then add the weighed mixed dry material into the mixing pot, place it on the mixing instrument, and start the automatic program (60s slow stirring, 60s fast stirring, 60s intermittent stirring, 60s fast stirring) to mix and stir to obtain a slurry.

[0062] S3. Place the mixed material slurry into the slurry mold and test its flowability. The flowability is 191 mm, and the mixing is complete. Pour it into a sample triple mold and wrap the mold with plastic wrap. Place it in a standard cement concrete curing chamber with a temperature of 20±2℃ and a humidity of over 90% for curing. Test its compressive and flexural strength after 7 days and 28 days of curing.

[0063] Comparative Example 2

[0064] The specific composition of the desulfurization wastewater used in this comparative example is shown in Table 4.

[0065] Table 4

[0066]

[0067] S1. Weigh 180g of cement and 820g of fly ash, mix them and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material;

[0068] S2. Weigh 220g of the above desulfurization wastewater (water-cement ratio of 0.22) and pour it into the mixing pot. Then add the weighed mixed dry material into the mixing pot, place it on the mixing instrument, and start the automatic program (60s slow stirring, 60s fast stirring, 60s intermittent stirring, 60s fast stirring) to mix and obtain a slurry.

[0069] S3. Place the mixed material slurry into the slurry mold and test its flowability. The flowability is 191 mm, and the mixing is complete. Pour it into a sample triple mold and wrap the mold with plastic wrap. Place it in a curing chamber with a temperature of 20±2℃ and a humidity of over 90% for curing. Test its compressive and flexural strength after 7 days and 28 days of curing.

[0070] Comparative Example 3

[0071] The non-fired brick mortar was prepared according to the method in Example 3 of application number 202210806524.4, and the materials were prepared as follows:

[0072] 21.16 parts by weight of PO42.5 cement, 8 parts by weight of fly ash, 35 parts by weight of slag, and 35.76 parts by weight of nanofiltration concentrate from a power plant desulfurization wastewater zero-discharge system (of which, sodium ion content is 1.22 × 10⁻⁶). 4 mg / L, the specific composition of nanofiltration concentrate is detailed in Table 1 of the patent specification; based on the total mass of cement and fly ash, 0.26% sodium lignosulfonate (0.0758 parts by mass, accounting for 0.0758% of the total ingredients) is added, wherein the glue-slag ratio is 1:1.2.

[0073] The preparation method is as follows:

[0074] The prepared cement, fly ash, slag, and sodium lignosulfonate are put into a roller mill mixing equipment for dry mixing. The concentrated water from the nanofiltration system of the power plant's desulfurization wastewater zero discharge system is added to the roller mill mixing equipment, and wet mixing is continued for 10 minutes to make a uniform plasticized slurry. The brick blanks are pressed into shape in a mold using a static pressure equipment, and then placed in deionized water for natural curing for 28 days.

[0075] The bricks / blocks obtained above were subjected to performance testing, and the test results are shown in Table 5 below:

[0076] Table 5

[0077]

[0078] Note: The 13.5 MPa given in Comparative Example 3 in the table is the 14-day compressive strength test data.

[0079] As can be seen from the data in the table above, the bricks / blocks prepared by the present invention through controlling the proportions of each raw material can achieve an average compressive strength of over 6 MPa after 7 days and an average compressive strength of over 11 MPa after 28 days.

[0080] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A mortar composition for bricks / blocks, characterized in that, The slurry composition is obtained by pulping the following raw materials: 62-70 parts by weight of fly ash, 7-15 parts by weight of cement, and 20-23 parts by weight of desulfurization wastewater, based on the weight of the raw materials. The sodium ion content in the desulfurization wastewater is 700~3000 mg / L, and the chloride ion content is 3000~14200 mg / L. The fly ash has a D50 of 2~25 μm.

2. The slurry composition according to claim 1, characterized in that, The desulfurization wastewater comes from the raw water or effluent of the desulfurization wastewater generated by flue gas desulfurization in coal-fired power plants. The desulfurization wastewater also includes the following components: calcium ion content of 700~3000 mg / L, magnesium ion content of 2500~16000 mg / L, potassium ion content of 20~130 mg / L, and sulfate ion content of 9000~58000 mg / L.

3. The slurry composition according to claim 1 or 2, characterized in that, Based on the weight parts of the raw materials, there are 65-68 parts of fly ash, 10-13 parts of cement, and 21-22 parts of desulfurization wastewater.

4. The slurry composition according to claim 3, characterized in that, The fly ash has a D50 of 6~15 μm.

5. The slurry composition according to claim 4, characterized in that, The cement is selected from ordinary Portland cement P.O42.5R.

6. A method for preparing bricks / blocks using the mortar composition according to any one of claims 1 to 5, characterized in that, The method includes the following steps: S1. Mix fly ash and cement and put them into a roller mill mixing equipment for dry mixing to obtain a mixed dry material; S2. The mixed dry material is added to the desulfurization wastewater and mixed and stirred to obtain a slurry; S3. Pour the slurry into a triple mold to form and cure it to obtain bricks / blocks.

7. The method according to claim 6, characterized in that, In S2, the water-to-material ratio of the desulfurization wastewater to the mixed dry material is 0.21 to 0.

23.

8. The method according to claim 7, characterized in that, The mixed dry material is added to the desulfurization wastewater and stirred until the fluidity is 190~193 mm, and the stirring is completed to obtain the slurry.

9. The method according to claim 8, characterized in that, In S3, maintenance is carried out at a temperature of 21~25℃ and a humidity of over 90%.

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