Carbon sequestration aerated concrete wall product based on nickel slag and concrete tailings and preparation method

Abstract

The application discloses a kind of carbon sequestration aerated concrete wall material product based on nickel slag and concrete tail slurry and preparation method, including nickel slag, concrete tail slurry, gypsum, cement, lime, aluminium powder paste and crystal nucleus agent;When preparing, first mix nickel slag, concrete tail slurry and gypsum uniformly, then add cement, lime and stir, finally add aluminium powder paste, crystal nucleus agent and stir, to prepare mixed material slurry, after injection film, maintenance, demolding, to prepare green body, and carry out carbonation maintenance.The application applies nickel slag and concrete tail slurry in aerated concrete wall material product, and combines the process of carbonation maintenance, on the basis of providing part siliceous raw materials and calcareous raw materials by nickel slag and concrete tail slurry, can fully stimulate low-activity large amount of silicate, aluminate and other minerals in nickel slag and concrete tail slurry, and under the induction of crystal nucleus agent, promote CO2 and calcium silicate component in nickel slag and concrete tail slurry to generate CaCO3 and SiO2 colloid, to provide reaction conditions for forming tobermorite.

Description

Technical Field

[0001] This invention belongs to the field of carbon-fixed aerated concrete wall products, and particularly relates to a method for preparing carbon-fixed aerated concrete wall products based on nickel slag and concrete tailings. Background Technology

[0002] Nickel slag, a carbon sequestration waste generated in large quantities during factory production, has not had its value widely explored. Domestic and international applications of nickel slag mainly focus on using it as coarse and fine aggregate in concrete preparation, or as a siliceous raw material in traditional concrete preparation. However, when using nickel slag as a siliceous material in traditional concrete products, expansion during hydration often causes cracking of the concrete blocks.

[0003] Concrete mixing plants generate a large amount of concrete tailings every year. A very small portion of the concrete tailings is recycled in concrete production, while a large amount is landfilled and stockpiled, which is also not effectively utilized and has an extremely negative impact on the environment.

[0004] Nickel slag has not been widely used in the traditional field of autoclaved aerated concrete (AAC). The reason is that nickel slag contains a large amount of low-activity minerals such as silicates and aluminates. Unlike silica sand and fly ash, these minerals cannot provide a large amount of active SiO2 for the formation of tobermorite, the main strength structure of AAC. To effectively improve the activity of nickel slag, the current common method is high-temperature calcination followed by rapid cooling. However, this thermal activation method is not only complex but also results in additional energy consumption, making it counterproductive.

[0005] Similarly, concrete tailings contain a large amount of low-activity minerals such as silicates and aluminates, which has prevented them from being fully utilized in the field of autoclaved aerated concrete. Summary of the Invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for preparing carbon-fixed aerated concrete wall products based on nickel slag and concrete tailings. This method can activate the activity of low-activity minerals such as silicates and aluminates in nickel slag and concrete tailings, and can fully utilize the low-activity silicate or aluminate components to provide reaction conditions for tobermorite.

[0007] Technical solution: The present invention is a carbon-fixed aerated concrete wall material product based on nickel slag and concrete tailings, which includes the following raw materials by weight: 25-32 parts nickel slag, 90-100 parts concrete tailings, 3-4 parts gypsum, 8-12 parts cement, 15-20 parts lime, 0.08-0.12 parts aluminum powder paste and 2-4 parts crystal nucleating agent.

[0008] Furthermore, the nucleating agent used in this carbon-fixed aerated concrete wall material is prepared by the following steps: adding 4-6% Ba(OH)2 and 2-5% polyethylene glycol by mass of Ca(OH)2 to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and injecting CO2 into the Ca(OH)2 suspension at a temperature of 20-50℃ for 15-30 minutes at a rate of 90-120 ml / min to obtain the nucleating agent.

[0009] The nucleating agent of this invention combines Ba(OH)₂ and polyethylene glycol. Utilizing the adsorption and nucleation site-providing effects of polyethylene glycol and Ba(OH)₂, it improves the dispersibility of CaCO₃ nuclei and the formation of spindle-shaped or rod-shaped crystals, ensuring the effective growth and adhesion of tobermorite and guaranteeing its excellent mechanical properties. Simultaneously, using this CaCO₃ suspension as a nucleating agent significantly reduces the total porosity of the cement paste, minimizing shrinkage of aerated concrete wall products, increasing the crystallinity of tobermorite, and thus improving the shrinkage resistance of aerated concrete wall products.

[0010] Furthermore, the nickel slag used in this carbon-fixed aerated concrete wall material is a solid waste slag produced by smelting nickel-iron alloys, with a magnesium oxide content of ≥10% and a silicon dioxide content of ≥40%.

[0011] Furthermore, the solid content of the concrete tailings used in this carbon-fixed aerated concrete wall material is 25-35%, the fineness is less than 20% residue on a 0.2mm square hole sieve, and the calcium oxide content is ≥30%.

[0012] The method for preparing the above-mentioned carbon-fixed aerated concrete wall material product of the present invention includes the following steps:

[0013] (1) Preparation of green body: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45 seconds, and finally add aluminum powder paste and crystal nucleating agent and stir for 5-10 seconds to obtain a mixed slurry. After casting, static curing and demolding, the green body is obtained.

[0014] (2) Carbonation curing: The green body is carbonized and cured for 2-3 hours at 80-90℃ and CO2 pressure of 2-3MPa to obtain the carbon-fixed aerated concrete wall material product.

[0015] Based on nickel slag, concrete tailings, and nucleating agents, this invention employs a carbonization curing method that can activate the large amount of low-activity minerals such as silicates and aluminates contained in nickel slag and concrete tailings. This promotes the formation of CaCO3 and SiO2 colloids from CO2 and the low-activity calcium silicate components in nickel slag and concrete tailings, providing the reaction conditions for tobermorite and enhancing the compressive strength of aerated concrete wall materials.

[0016] Furthermore, in step (1) of the preparation method of the present invention, static curing is performed at 50-60℃ for 4-6 hours.

[0017] Beneficial effects: Compared with the prior art, the significant advantages of this invention are as follows: This invention applies nickel slag and concrete tailings to aerated concrete wall products, and combines them with carbonation curing process. On the basis of nickel slag and concrete tailings providing some siliceous and calcareous raw materials, it can also fully activate a large number of low-activity silicate and aluminate minerals in nickel slag and concrete tailings. Under the induction of nucleating agent, it promotes the formation of CaCO3 and SiO2 colloids by CO2 and calcium silicate components in nickel slag and concrete tailings, providing reaction conditions for the formation of tobermorite, thereby further enhancing the compressive strength of aerated concrete wall materials. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0019] It should be noted that the nickel slag used in this invention was purchased from Jiangsu Delong Nickel Industry Co., Ltd., and is a solid waste slag produced from the smelting of nickel-iron alloys, with a magnesium oxide content ≥10% and a silicon dioxide content ≥40%. The concrete tailings, obtained from site cleaning, mixer truck cleaning, mixing equipment cleaning, and sand and gravel separation, were purchased from Jiangsu Zhongding Building Materials Group Co., Ltd., and consist of unhydrated cement slurry, mineral powder, fly ash, and fine sand, with a solid content of 25-35%. The cement is 42.5 ordinary Portland cement or Portland cement. The lime is industrial-grade quicklime, with a residue of 8%-15% on an 80μm square-hole sieve. The gypsum is desulfurized gypsum, with a CaSO4·2H2O content ≥92%. The aluminum powder paste is industrial-grade aluminum powder paste, with an active aluminum content ≥90%.

[0020] Example 1

[0021] The raw material composition of this embodiment is shown in Table 1 below.

[0022] Table 1 Raw material components of Example 1

[0023] 1 Nickel slag 25 2 Concrete tailings 100 3 cement 8 4 lime 15 5 plaster 3 6 Aluminum Powder Paste 0.12 7 nucleating agent 3

[0024] The nucleating agent is prepared by the following steps: Ba(OH)2 and polyethylene glycol are added to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and CO2 is injected into the Ca(OH)2 suspension at a temperature of 20-25℃ at a rate of 90-120 ml / min for 15-30 min to obtain the nucleating agent; wherein the dosage of Ba(OH)2 and polyethylene glycol is 5% and 3% of the mass of Ca(OH)2, respectively.

[0025] The method for preparing carbon-fixed aerated concrete wall material products based on nickel slag and concrete tailings in this embodiment includes the following steps:

[0026] (1) Mixing and stirring: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45 seconds, and finally add aluminum powder paste and nucleating agent and stir for 5-10 seconds to obtain a mixed slurry.

[0027] (2) Slurry injection: The well-stirred slurry is injected into the specimen that has been sprayed with release agent;

[0028] (3) Static curing: The specimens are sent to the curing workshop for static foaming at a temperature of 50-60℃ for 4-6 hours.

[0029] (4) Demolding and cutting: Use a cutting machine to cut according to requirements and remove damaged or non-conforming parts;

[0030] (5) Carbonization curing: The cut aerated brick blanks are transported to the carbonization kettle by a railcar. They are carbonized and cured for 2 hours at 82℃ and CO2 pressure of 2.4MPa, and then removed from the kettle to obtain carbon-fixed aerated concrete wall material products.

[0031] Example 2

[0032] The raw material composition of this embodiment is shown in Table 2 below.

[0033] Table 2 Raw material components of Example 2

[0034] 1 Nickel slag 32 2 Concrete tailings 90 3 cement 12 4 lime 16 5 plaster 4 6 Aluminum Powder Paste 0.1 7 nucleating agent 2

[0035] The nucleating agent is prepared by the following steps: Ba(OH)2 and polyethylene glycol are added to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and CO2 is injected into the Ca(OH)2 suspension at a temperature of 20-25℃ at a rate of 90-120 ml / min for 15-30 min to obtain the nucleating agent; wherein the dosage of Ba(OH)2 and polyethylene glycol is 4% and 4% of the mass of Ca(OH)2, respectively.

[0036] The method for preparing carbon-fixed aerated concrete wall material products based on nickel slag and concrete tailings in this embodiment includes the following steps:

[0037] (1) Mixing and stirring: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45 seconds, and finally add aluminum powder paste and nucleating agent and stir for 5-10 seconds to obtain a mixed slurry.

[0038] (2) Slurry injection: The well-stirred slurry is injected into the specimen that has been sprayed with release agent;

[0039] (3) Static curing: The specimens are sent to the curing workshop for static foaming at a temperature of 50-60℃ for 4-6 hours.

[0040] (4) Demolding and cutting: Use a cutting machine to cut according to requirements and remove damaged or non-conforming parts;

[0041] (5) Carbonization curing: The cut aerated brick blanks are transported to the carbonization kettle by a railcar. They are carbonized and cured for 2 hours at 80℃ and CO2 pressure of 2.0MPa, and then removed from the kettle to obtain carbon-fixed aerated concrete wall material products.

[0042] Example 3

[0043] The raw material composition of this embodiment is shown in Table 3 below.

[0044] Table 3 Raw material components of Example 3

[0045] 1 Nickel slag 30 2 Concrete tailings 96 3 cement 9 4 lime 20 5 plaster 3 6 Aluminum Powder Paste 0.08 7 nucleating agent 4

[0046] The nucleating agent is prepared by the following steps: Ba(OH)2 and polyethylene glycol are added to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and CO2 is injected into the Ca(OH)2 suspension at a temperature of 20-25℃ at a rate of 90-120 ml / min for 15-30 min to obtain the nucleating agent; wherein the dosage of Ba(OH)2 and polyethylene glycol is 6% and 2% of the mass of Ca(OH)2, respectively.

[0047] The method for preparing carbon-fixed aerated concrete wall material products based on nickel slag and concrete tailings in this embodiment includes the following steps:

[0048] (1) Mixing and stirring: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45 seconds, and finally add aluminum powder paste and nucleating agent and stir for 5-10 seconds to obtain a mixed slurry.

[0049] (2) Slurry injection: The well-stirred slurry is injected into the specimen that has been sprayed with release agent;

[0050] (3) Static curing: The specimens are sent to the curing workshop for static foaming at a temperature of 50-60℃ for 4-6 hours.

[0051] (4) Demolding and cutting: Use a cutting machine to cut according to requirements and remove damaged or non-conforming parts;

[0052] (5) Carbonization curing: The cut aerated brick blanks are transported to the carbonization kettle by a railcar. They are carbonized and cured for 2 hours at 82℃ and CO2 pressure of 2.4MPa, and then removed from the kettle to obtain carbon-fixed aerated concrete wall material products.

[0053] Example 4

[0054] The raw material composition of this embodiment is shown in Table 4 below.

[0055] Table 4 Raw material components of Example 4

[0056] 1 Nickel slag 28 2 Concrete tailings 92 3 cement 10 4 lime 18 5 plaster 4 6 Aluminum Powder Paste 0.11 7 nucleating agent 4

[0057] The nucleating agent is prepared by the following steps: Ba(OH)2 and polyethylene glycol are added to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and CO2 is injected into the Ca(OH)2 suspension at a temperature of 20-25℃ at a rate of 90-120 ml / min for 15-30 min to obtain the nucleating agent; wherein the dosage of Ba(OH)2 and polyethylene glycol is 5% and 5% of the mass of Ca(OH)2, respectively.

[0058] The method for preparing carbon-fixed aerated concrete wall material products based on nickel slag and concrete tailings in this embodiment includes the following steps:

[0059] (1) Mixing and stirring: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45 seconds, and finally add aluminum powder paste and nucleating agent and stir for 5-10 seconds to obtain a mixed slurry.

[0060] (2) Slurry injection: The well-stirred slurry is injected into the specimen that has been sprayed with release agent;

[0061] (3) Static curing: The specimens are sent to the curing workshop for static foaming at a temperature of 50-60℃ for 4-6 hours.

[0062] (4) Demolding and cutting: Use a cutting machine to cut according to requirements and remove damaged or non-conforming parts;

[0063] (5) Carbonization curing: The cut aerated brick blanks are transported to the carbonization kettle by a railcar. They are carbonized and cured for 3 hours at 90°C and CO2 pressure of 3MPa, and then removed from the kettle to obtain carbon-fixed aerated concrete wall material products.

[0064] Example 5

[0065] The raw material composition of this embodiment is shown in Table 5 below.

[0066] Table 5 Raw material components of Example 5

[0067] 1 Nickel slag 26 2 Concrete tailings 95 3 cement 11 4 lime 19 5 plaster 3 6 Aluminum Powder Paste 0.09 7 nucleating agent 3

[0068] The nucleating agent is prepared by the following steps: Ba(OH)2 and polyethylene glycol are added to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and CO2 is injected into the Ca(OH)2 suspension at a temperature of 20-25℃ at a rate of 90-120 ml / min for 15-30 min to obtain the nucleating agent; wherein the dosage of Ba(OH)2 and polyethylene glycol is 4% and 5% of the mass of Ca(OH)2, respectively.

[0069] The method for preparing carbon-fixed aerated concrete wall material products based on nickel slag and concrete tailings in this embodiment includes the following steps:

[0070] (1) Mixing and stirring: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45 seconds, and finally add aluminum powder paste and nucleating agent and stir for 5-10 seconds to obtain a mixed slurry.

[0071] (2) Slurry injection: The well-stirred slurry is injected into the specimen that has been sprayed with release agent;

[0072] (3) Static curing: The specimens are sent to the curing workshop for static foaming at a temperature of 50-60℃ for 4-6 hours.

[0073] (4) Demolding and cutting: Use a cutting machine to cut according to requirements and remove damaged or non-conforming parts;

[0074] (5) Carbonization curing: The cut aerated brick blanks are transported to the carbonization kettle by a railcar. They are carbonized and cured for 2 hours at 90℃ and CO2 pressure of 3.0MPa to obtain carbon-fixed aerated concrete wall material products.

[0075] Comparative Example 1

[0076] The basic steps are the same as in Example 1, except that the nucleating agent used is the existing hydrated magnesium silicate nucleating agent.

[0077] Comparative Example 2

[0078] The basic steps are the same as in Example 1, except that the existing sodium silicate nucleating agent is used.

[0079] The dry density and strength of the carbon-fixed aerated concrete wall products prepared in Examples 1-5 and Comparative Examples 1-2 were tested, and the test results are summarized in Table 6.

[0080] Table 6. Test results of aerated concrete blocks from Examples 1-5 and Comparative Examples 1-2

[0081] Example 1 609 3.6 Example 2 621 3.5 Example 3 623 3.9 Example 4 617 3.7 Example 5 606 3.6 Comparative Example 1 652 1.9 Comparative Example 2 640 1.8

[0082] As shown in Table 6, the aerated concrete wall products prepared by this invention based on nickel slag and concrete tailings, combined with a specific nucleating agent and carbonization oxidation, exhibit significantly higher compressive strength than those of Comparative Examples 1 and 2. This demonstrates that the carbonization oxidation process of this invention, combined with a specific nucleating agent, can simultaneously and effectively activate a large number of low-activity silicate and aluminate minerals in nickel slag and concrete tailings, promoting the formation of CaCO3 and SiO2 colloids from CO2 and calcium silicate components in nickel slag and concrete tailings. This provides the reaction conditions for the formation of tobermorite, thereby further enhancing the compressive strength of the aerated concrete wall material.

Claims

1. A carbon-fixed aerated concrete wall material product based on nickel slag and concrete tailings, characterized in that... The raw materials include the following by weight: 25-32 parts nickel slag, 90-100 parts concrete tailings, 3-4 parts gypsum, 8-12 parts cement, 15-20 parts lime, 0.08-0.12 parts aluminum powder paste, and 2-4 parts crystal nucleating agent; The nucleating agent is prepared by the following steps: adding 4-6% Ba(OH)2 and 2-5% polyethylene glycol by mass of Ca(OH)2 to a Ca(OH)2 suspension with a concentration of 1-1.2 mol / L, and injecting CO2 into the Ca(OH)2 suspension at a temperature of 20-50℃ for 15-30 minutes at a rate of 90-120 ml / min to obtain the nucleating agent; The preparation method of this carbon-fixed aerated concrete wall material includes the following steps: (1) Preparation of green body: First, mix nickel slag, concrete tailings and gypsum evenly, then add cement and lime and stir for 30-45s, and finally add aluminum powder paste and nucleating agent and stir for 5-10s to obtain a mixed slurry. After molding, static curing and demolding, the green body is obtained. (2) Carbonation curing: The green body is carbonized and cured for 2-3 hours at 80-90℃ and CO2 pressure of 2-3MPa to obtain the carbon-fixed aerated concrete wall material product.

2. The carbon-fixed aerated concrete wall material product according to claim 1, characterized in that: The nickel slag is a solid waste slag produced by smelting nickel-iron alloys, wherein the magnesium oxide content is ≥10% and the silicon dioxide content is ≥40%.

3. The carbon-fixed aerated concrete wall material product according to claim 1, characterized in that: The solid content of the concrete tailings is 25-35%, the fineness is less than 20% residue on a 0.2mm square hole sieve, and the calcium oxide content is ≥30%.

4. The carbon-fixed aerated concrete wall material product according to claim 1, characterized in that: In step (1), the static curing is performed at 50-60℃ for 4-6 hours.