Desulfurizing liquid erosion resistant concrete and preparation method thereof

Abstract

The invention provides desulfurization solution erosion resistant concrete and a preparation method thereof. The desulfurization solution erosion resistant concrete is suitable for coke oven gas desulfurization solution alkaline and various composite salt ion erosion environments. The concrete is formed by compounding water, cement, fly ash, superfine slag powder, a capillary crystalline material, limestone coarse aggregate, limestone fine aggregate and a polycarboxylate water reducing agent according to a preset weight part ratio, the selection of the limestone aggregate ensures the stability of the aggregate structure in alkaline and salty erosion environments, and the synergistic effect of fly ash and superfine slag powder in the admixture ensures the stability of the aggregate structure in the alkaline and salty erosion environments. The compactness and the composite salt corrosion resistance of the concrete are improved, and the composite salt ion penetration resistance is enhanced through internal doping of the capillary crystalline material. According to the preparation method, the concrete with stable performance is obtained by premixing part of the cement and the capillary crystalline material, sequentially mixing and performing standard curing. The durability and the service life of the concrete under the erosion condition of the coke oven gas desulfurization liquid are remarkably improved, the environmental pollution is reduced, and good economic benefits and application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a concrete resistant to desulfurization liquid erosion and its preparation method. Background Technology

[0002] Coke oven gas is a combustible gas produced during the coking process. Its main components include methane, hydrogen, carbon monoxide, and carbon dioxide. Wet catalytic oxidation technology is a commonly used desulfurization method for coke oven gas. This process uses ammonia in the coke oven gas as an alkali source, reacting with pollutants such as hydrogen sulfide and hydrogen cyanide to generate various complex salts. The main complex salt anions include sulfate, sulfite, thiosulfate, thiocyanate, and carbonate. The byproduct is coke oven gas desulfurization liquid.

[0003] Coke oven gas desulfurization liquid is generally a weakly alkaline solution with a pH of 8-9. In one enterprise, the total salt concentration in the coke oven gas desulfurization liquid could reach as high as 21%, with the content of these salt ions reaching 250 g / L under extreme conditions. This far exceeds the 3%-5% of conventional concrete erosion test solutions. Under such conditions, ordinary concrete is extremely prone to failure, and its protective layer is easily damaged by various factors such as mechanical damage, chemical erosion, and aging under open-air conditions. Furthermore, it is difficult to repair quickly, posing a significant hidden danger to the coal coking desulfurization production process.

[0004] Existing technologies have included the research and application of various sulfate-resistant concretes. The main measures to prevent and mitigate sulfate erosion of concrete are based on the following two aspects: first, the rational selection of cement types and admixtures; and second, improving the density of concrete materials or setting a protective layer on the concrete surface.

[0005] For example, Chinese invention patent application number 202111676692.8 discloses a sulfate-resistant concrete and its preparation method. The sulfate-resistant concrete prepared by this invention consists of a concrete matrix and an anti-corrosion coating. In preparing the concrete matrix, sulfate-resistant cement and a coagulant are used to reduce the heat of hydration released during cement hydration and prevent micro-cracks caused by thermal stress. This invention requires the separate preparation of the concrete matrix and the anti-corrosion coating, involves many types of raw materials, has a complex process, and the coating has low strength, making it easily damaged by complex operating environments and unsuitable for the corrosive environment of coke oven gas desulfurization liquid.

[0006] For example, Chinese invention patent application number 202311821325.1 discloses a sulfate-resistant concrete and its preparation method. The main contents of this invention are as follows: the concrete includes water, cement, fly ash, an anti-sulfate corrosion agent, fine aggregate, coarse aggregate, and polycarboxylate superplasticizer; wherein the fly ash has a 45μm square-hole sieve residue of 45%-53%, a 28-day strength activity index of 62%-69%, and a CaO content of 10%-15% in its chemical composition. The anti-sulfate corrosion agent consists of raw material components including tailings slag, water glass, barium salts, chloroprene latex, and latex modifiers. The tailings slag includes at least one of lithium ore, iron ore, copper ore, chromium ore, and manganese ore, and the Si / Ca mass ratio in the tailings slag is 4.6-7.8. This invention uses the anti-sulfate corrosion agent as its core, activating the pozzolanic activity of low-grade fly ash, thereby improving the sulfate resistance of the concrete material. However, the invention uses a variety of raw materials and involves complex processes. Organic sulfate-resistant agents have poor anti-aging properties and are easily damaged or corroded in complex operating environments, making them unsuitable for the corrosive environment of coke oven gas desulfurization liquid.

[0007] In summary, the aforementioned existing technologies are mostly designed for general sulfate-eroded environments. They suffer from problems such as complex raw material types, cumbersome preparation processes, reliance on organic corrosion inhibitors which are prone to aging and failure, or reliance on coatings which are easily damaged in complex environments. They are not suitable for the corrosive environment of coke oven gas desulfurization liquid, which contains multiple complex salts, is alkaline, and is highly corrosive.

[0008] Therefore, there is currently no general concrete and its preparation technology that can be directly applied to the erosion conditions of desulfurization liquid in coke oven gas. There is an urgent need to develop a type of concrete and its preparation method that can maintain structural stability in this environment for a long time, is easy to prepare, and is highly adaptable to the erosion conditions of desulfurization liquid. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a desulfurization liquid-resistant concrete and its preparation method. It primarily utilizes the structural stability of limestone coarse and fine aggregates in alkaline environments and environments containing multiple complex salt ions. The synergistic effect of fly ash and slag powder is combined to stimulate the secondary hydration reaction of fly ash, improving the density and resistance to complex salt erosion in the concrete. Furthermore, the internal adsorption of penetrating crystalline materials further enhances the concrete's resistance to complex salt ions. Simultaneously, polycarboxylate superplasticizers improve mixing performance and density. Therefore, under the complex corrosive environment of coke oven gas desulfurization liquid, this invention significantly extends the service life of the concrete and its associated structures, reduces environmental pollution risks, simplifies the preparation process, and also considers economic benefits.

[0010] The technical means employed in this invention are as follows:

[0011] A type of concrete resistant to desulfurization liquid corrosion, the concrete being suitable for the corrosive environment of coke oven gas desulfurization liquid, maintaining stable mechanical properties under alkaline conditions and conditions containing multiple complex salt ions, comprising the following components by weight:

[0012] 160-180 parts water;

[0013] 450-480 parts cement;

[0014] 45-72 parts fly ash;

[0015] 45-192 parts of slag powder;

[0016] 12-20 parts of penetrating crystallizing material;

[0017] 660-710 parts fine aggregate;

[0018] 1044-1144 parts coarse aggregate;

[0019] 2.6-3.5 parts of polycarboxylate superplasticizer.

[0020] Furthermore, the multiple complex salt ions include sulfate, sulfite, thiosulfate, thiocyanate, and carbonate.

[0021] Furthermore, the cement is ordinary Portland cement PO 42.5, the fly ash is grade II or above, the slag powder is grade S95 or above, and the penetrating crystallizing material is an internal admixture.

[0022] Furthermore, the fine aggregate is continuously graded limestone medium sand with a fineness modulus of 2.6-3.0 and an average particle size of 0.5-0.42 mm; the coarse aggregate is limestone crushed stone with a particle size of 5.1-25.0 mm.

[0023] Furthermore, the water reduction efficiency of the polycarboxylate superplasticizer is 25%-30%.

[0024] This invention also discloses a method for preparing the above-mentioned concrete resistant to desulfurization liquid erosion, comprising the following steps:

[0025] S1. Divide the cement into two parts, wherein 5%-10% of the cement is premixed with the penetrating crystallizing material to obtain a premix for later use;

[0026] S2. Add coarse aggregate, fine aggregate, remaining cement, fly ash and slag powder to the mixing equipment in sequence and dry mix evenly. Then add the premixed material from step S1 and continue dry mixing. Then add an appropriate amount of water and polycarboxylate superplasticizer, mix evenly, and obtain concrete mix.

[0027] S3. Set the concrete mix to the desired shape and complete the curing process according to the standard curing procedure.

[0028] Furthermore, in step S2, the weight ratio of fly ash to slag powder is 1:1 to 1:4.2 to enhance the effect of secondary hydration reaction.

[0029] Furthermore, the dry mixing time in step S2 is 60-180 seconds to ensure that the fly ash and slag powder are evenly dispersed.

[0030] Furthermore, in step S2, water and polycarboxylate superplasticizer are added sequentially to ensure the uniformity and workability of the concrete mix.

[0031] By adopting the above technical solution, the present invention has the following beneficial effects:

[0032] 1. The limestone coarse and fine aggregates used in this invention exhibit stable chemical properties in the weakly alkaline environment and high-concentration salt solution of coke oven gas desulfurization liquid, making them less prone to rapid and significant performance degradation due to the erosion of complex salt ions. Compared to conventional granite, basalt, and other aggregates, limestone aggregates maintain structural stability better in alkaline and salty environments, thus ensuring the mechanical properties and durability of the overall concrete matrix under long-term service conditions, while also meeting the explosion-proof requirements of coal chemical industry.

[0033] 2. The fly ash used in this invention is a potential active material. By combining it with S95 grade or higher slag powder, and utilizing the alkaline environment released by the active calcium oxide and magnesium oxide components in the slag, a secondary hydration reaction is activated in the active silica and alumina in the fly ash, generating more CSH gel and hydration products. These products can fill pores, increase the density of concrete, reduce ion migration channels, and thus improve resistance to salt erosion and expansion.

[0034] 3. The penetrating crystallizing material used in this invention can react with free calcium ions in cement to generate insoluble crystals, which continuously grow along capillary pores and microcracks, forming a stable crystalline sealing layer. This "self-healing" mechanism can effectively prevent SO4 from entering the desulfurization liquid of coke oven gas. 2- SCN - S2O3 2- and CO3 2- The infiltration of complex salt ions significantly improves the concrete's impermeability and overall resistance to desulfurization liquid erosion.

[0035] In summary, the concrete prepared by this invention possesses strong resistance to desulfurization liquid erosion, thus eliminating the need for an external protective layer. This avoids failure issues caused by low coating strength or easy aging, and improves the concrete's overall resistance to mechanical impact, physical wear, and complex salt erosion. It is particularly suitable for complex operating environments under desulfurization liquid erosion conditions, such as areas requiring frequent maintenance, prone to mechanical damage, and susceptible to aging.

[0036] The preparation method employed in this invention is simple, requiring only the premixing of a portion of ordinary cement with a penetrating crystallizing material before mixing, followed by sequential mixing with aggregates, fly ash, and slag powder to obtain high-performance concrete. Compared to existing technologies, it uses fewer raw materials, requires no special cement, contains no organic components, exhibits strong anti-aging properties, and is simple and efficient in production and construction. This concrete has a significantly extended service life, thereby reducing maintenance costs and replacement frequency, minimizing environmental pollution risks, and possesses significant economic benefits and widespread application value. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a photograph of the concrete test block used in Embodiment 1 of the present invention.

[0039] Figure 2 This is a photograph of the concrete test block used in Embodiment 2 of the present invention.

[0040] Figure 3 This is a photograph of the concrete test block used in Embodiment 2 of the present invention.

[0041] Figure 4 These are experimental images showing the erosion of concrete test blocks in desulfurization liquid in an embodiment of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] The present invention provides a concrete resistant to desulfurization liquid corrosion, which is suitable for the corrosion environment of coke oven gas desulfurization liquid. It maintains stable mechanical properties under alkaline conditions and corrosion conditions containing multiple complex salt ions, including sulfate, sulfite, thiosulfate, thiocyanate and carbonate, and also contains other low-concentration salts.

[0045] The concrete comprises the following components by weight: 165 parts water, 460 parts cement, 46 parts fly ash, 190 parts slag powder, 14 parts penetrating crystallizing material, 700 parts fine aggregate, 1040 parts coarse aggregate, and 2.7 parts polycarboxylate superplasticizer.

[0046] The fly ash is grade II or higher, the slag powder is grade S95 or higher, the cement is ordinary Portland cement P.O42.5, and the penetrating crystallizing material is an internal admixture. The fine aggregate is continuously graded limestone medium sand with a fineness modulus of 2.6 and an average particle size of 0.43 mm. The coarse aggregate is crushed limestone with a particle size of 5.1-19.0 mm. The polycarboxylate water-reducing agent has a water reduction efficiency of 25%.

[0047] By adopting the above technical solutions, the limestone coarse and fine aggregates used in this application can maintain stable aggregate performance under the alkaline and high-concentration multi-salt erosion environment of desulfurization liquid. The combined use of slag powder and fly ash can stimulate the secondary hydration reaction of fly ash, improving the density of concrete and its resistance to multi-salt erosion and expansion. In addition, the composite use of penetrating crystallizing materials can significantly improve the concrete's resistance to the penetration of complex salt ions from desulfurization liquid, further enhancing the concrete's resistance to desulfurization liquid erosion.

[0048] The above-mentioned method for preparing concrete includes the following steps:

[0049] S1. Divide the cement into two parts, one of which is about 5%. Mix it with the penetrating crystallizing material beforehand to make a premixed material.

[0050] S2. Add coarse aggregate, fine aggregate, remaining cement, fly ash, and slag powder to the mixing equipment in sequence and dry mix evenly for 120 seconds. Then add the premixed material from S1 and continue dry mixing. Finally, add an appropriate amount of water and polycarboxylate superplasticizer and mix evenly to complete the concrete mixing. Water and polycarboxylate superplasticizer should be added in sequence to ensure the uniformity and workability of the concrete mix.

[0051] S3. Set the mixed concrete to its final shape, and then complete the curing process according to standard procedures, such as... Figure 1 As shown.

[0052] Example 2

[0053] Based on Example 1, a concrete resistant to desulfurization liquid erosion comprises the following components by weight: 175 parts water, 479 parts cement, 70 parts fly ash, 100 parts slag powder, 19 parts penetrating crystallizing material, 700 parts fine aggregate, 1040 parts coarse aggregate, and 3.2 parts polycarboxylate superplasticizer. The fly ash is grade II or higher, the slag powder is grade S95 or higher, the cement is ordinary Portland cement PO 42.5, and the penetrating crystallizing material is an internal admixture. The fine aggregate is continuously graded limestone medium sand with a fineness modulus of 2.7 and an average particle size of 0.45 mm; the coarse aggregate is crushed limestone with a particle size of 5.1-20.0 mm. The polycarboxylate superplasticizer has a water reduction efficiency of 27%.

[0054] The preparation method differs from Example 1 in that, in step S1, the cement is divided into two parts, one of which is approximately 8.5%, and this part is premixed with the penetrating crystallizing material to form a premixed material. The final concrete specimen image is shown below. Figure 2 As shown.

[0055] Example 3

[0056] Based on Example 1, a concrete resistant to desulfurization liquid erosion comprises the following components by weight: 180 parts water, 475 parts cement, 68 parts fly ash, 190 parts slag powder, 20 parts penetrating crystallizing material, 700 parts fine aggregate, 1040 parts coarse aggregate, and 3.4 parts polycarboxylate superplasticizer. The fly ash is grade II or higher, the slag powder is grade S95 or higher, the cement is ordinary Portland cement PO 42.5, and the penetrating crystallizing material is an internal admixture. The fine aggregate is continuously graded limestone medium sand with a fineness modulus of 2.79 and an average particle size of 0.47 mm; the coarse aggregate is crushed limestone with a particle size of 5.5-24.0 mm. The polycarboxylate superplasticizer has a water reduction efficiency of 28%.

[0057] The preparation method differs from Examples 1 and 2 in that, in step S1, the cement is divided into two parts, one of which, approximately 10%, is premixed with the penetrating crystallizing material to form a premixed material. The final concrete specimen image is shown below. Figure 3 As shown.

[0058] Performance testing:

[0059] There are currently no domestic or international standards for testing the corrosion resistance of concrete to desulfurization liquid. Therefore, a sample of desulfurization liquid was taken from a company's site. Its main components were NaSCN: 89.25 g / L, Na2S2O3: 57.93 g / L, Na2SO4: 42.61 g / L, Na2CO3: 3.15 g / L, NaHCO3: 8.12 g / L, and pH value 8.1.

[0060] After the prepared concrete has been cured under standard conditions for 28 days, it is immersed in the solution for a period of time, with the immersion liquid level at least 20 mm above the surface of the concrete specimen. Then, its compressive strength is tested to characterize the concrete's resistance to desulfurization liquid erosion (e.g., Figure 4 (As shown).

[0061] The ordinary concrete used in the comparative experiment was concrete without the addition of slag powder, fly ash, and penetrating crystallizing materials, while other raw materials and experimental conditions were the same.

[0062] The test results are shown in Table 1.

[0063] Table 1. Test data on concrete resistance to desulfurization liquid erosion

[0064]

[0065] As shown in Table 1, the compressive strength of the concrete in Examples 1-3 is superior to that of the ordinary concrete in the comparative example under both standard curing conditions and desulfurization liquid immersion conditions. In particular, the compressive strength is still stable after 180 days of immersion in desulfurization liquid, without showing a significant downward trend. In contrast, the ordinary concrete of the comparative formula shows a continuous downward trend under desulfurization liquid immersion conditions. This indicates that the concrete formula of the present invention is reasonable, has high compressive strength, and can effectively improve the concrete's resistance to sulfuric acid erosion by desulfurization liquid.

[0066] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of concrete resistant to desulfurization liquid corrosion, characterized in that, The concrete is suitable for the corrosive environment of coke oven gas desulfurization liquid, and maintains stable mechanical properties under alkaline conditions and corrosive conditions containing multiple complex salt ions. It comprises the following components by weight: 160-180 parts water; 450-480 parts cement; 45-72 parts fly ash; 45-192 parts of slag powder; 12-20 parts of penetrating crystallizing material; 660-710 parts fine aggregate; 1044-1144 parts coarse aggregate; 2.6-3.5 parts of polycarboxylate superplasticizer.

2. The desulfurization liquid erosion-resistant concrete according to claim 1, characterized in that, The coke oven gas desulfurization liquid contains a variety of complex salt ions, including sulfate, sulfite, thiosulfate, thiocyanate, and carbonate.

3. The desulfurization liquid erosion-resistant concrete according to claim 2, characterized in that, The cement is ordinary Portland cement PO 42.5, the fly ash is grade II or above, the slag powder is grade S95 or above, and the penetrating crystallizing material is an internal admixture.

4. The desulfurization liquid erosion-resistant concrete according to claim 2, characterized in that, The fine aggregate is continuously graded limestone medium sand with a fineness modulus of 2.6-3.0 and an average particle size of 0.5-0.42 mm; the coarse aggregate is limestone crushed stone with a particle size of 5.1-25.0 mm.

5. The desulfurization liquid erosion-resistant concrete according to claim 2, characterized in that, The water reduction efficiency of the polycarboxylate superplasticizer is 25%-30%.

6. A method for preparing desulfurization liquid-resistant concrete according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Divide the cement into two parts, wherein 5%-10% of the cement is premixed with the penetrating crystallizing material to obtain a premix for later use; S2. Add coarse aggregate, fine aggregate, remaining cement, fly ash and slag powder to the mixing equipment in sequence and dry mix evenly. Then add the premixed material from step S1 and continue dry mixing. Then add an appropriate amount of water and polycarboxylate superplasticizer, mix evenly, and obtain concrete mix. S3. Set the concrete mix to the desired shape and complete the curing process according to the standard curing procedure.

7. The method for preparing desulfurization liquid-resistant concrete according to claim 6, characterized in that, In step S2, the weight ratio of fly ash to slag powder is 1:1 to 1:4.2 to enhance the effect of secondary hydration reaction.

8. The method for preparing desulfurization liquid-resistant concrete according to claim 6, characterized in that, The dry mixing time in step S2 is 60-180 seconds to ensure that fly ash and slag powder are evenly dispersed.

9. The method for preparing desulfurization liquid-resistant concrete according to claim 7, characterized in that, In step S2, water and polycarboxylate superplasticizer are added sequentially to ensure the uniformity and workability of the concrete mix.

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