Phosphogypsum-based aerated concrete block and preparation method thereof

Abstract

The invention discloses a phosphogypsum-based aerated concrete block and a preparation method thereof, and belongs to the field of aerated concrete. According to the aerated concrete block disclosed by the invention, phosphogypsum is used as a main raw material and is matched with cementing materials such as slag and cement, and modified titanium dioxide and basalt fibers are introduced. By adopting the composite foaming agent, the pore structure of the building block is optimized to form a uniform closed pore structure; the modified titanium dioxide and basalt fiber are adopted, so that the mechanical strength and durability of the building block are enhanced. According to the invention, the problem of environmental pollution caused by phosphogypsum accumulation can be well solved, and high-value utilization of phosphogypsum is realized; and the prepared concrete block has the advantages of light weight, high strength, thermal insulation and the like, and is suitable for building walls and green building materials.

Description

Technical Field

[0001] The invention relates to the field of aerated concrete, and in particular to a phosphogypsum-based aerated concrete building block and a preparation method thereof. Background Art

[0002] Aerated concrete blocks are solid blocks made of siliceous and calcareous materials as the main raw materials, mixed with gas-generating agents, and formed by stirring, autoclaving and curing. Aerated concrete blocks are light, porous, and have closed, static air inside to block the conduction of heat. They have excellent thermal insulation, heat insulation, sound absorption, and certain strength and processability, making them necessary green energy-saving ecological materials for the walls of new high-rise buildings.

[0003] Phosphogypsum is a solid waste produced during the production of phosphoric acid. Its main component is CaSO 4 ·2H 2 O, with a mass fraction of more than 90%. With the rapid development of China's phosphate fertilizer industry, the annual increase in phosphogypsum is as high as 50 million tons, but the actual utilization rate of phosphogypsum is less than 30%. Since phosphogypsum contains many harmful substances such as phosphorus and fluorine, it will cause environmental pollution if it is discharged arbitrarily. Large-scale storage not only occupies a large area of ​​land, but also has high requirements for geological conditions. Long-term accumulation will also cause surface water and groundwater pollution. Therefore, the treatment of phosphogypsum has become a major bottleneck restricting the development of the phosphate fertilizer industry. If phosphogypsum can be made into a new type of wall material, it will undoubtedly significantly improve the utilization rate of phosphogypsum and greatly alleviate the storage pressure of phosphogypsum.

[0004] Chinese patent CN112142428A discloses a method for preparing undisturbed phosphogypsum autoclaved aerated concrete, wherein the undisturbed phosphogypsum autoclaved aerated concrete comprises the following components weighed by mass: undisturbed phosphogypsum 100-831g, fly ash 500-1000g, lime 50-250g, cementitious material 50-250g, water reducer 1-2g, alkali activator 1-20g, foaming agent 1-15g, water 400-800g; the undisturbed phosphogypsum solid content is above 50%, and the viscosity range is 1000-4000Pa·S. The invention uses 10-39% of phosphogypsum solid waste for the preparation of aerated concrete, which has the problem of low phosphogypsum dosage, greatly reducing the resource value of phosphogypsum solid waste, and the use of undisturbed phosphogypsum may cause environmental problems.

[0005] Therefore, how to rationally utilize phosphogypsum, realize the recycling of solid waste resources, and prepare high-performance aerated concrete that meets multiple uses is a technical problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the problems of the prior art, the main purpose of the present invention is to provide a phosphogypsum-based aerated concrete block and a preparation method thereof. The aerated concrete block of the present invention has the advantages of high compressive strength and good thermal insulation performance.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A phosphogypsum-based aerated concrete block comprises the following raw materials in parts by weight: 20-30 parts of slag, 8-12 parts of cement, 60-70 parts of phosphogypsum, 4-7 parts of quicklime, 0.8-1.2 parts of foaming agent, 1-2 parts of alkali activator, 5-8 parts of modified titanium dioxide, and 80-90 parts of water; the phosphogypsum is calcined at high temperature to generate beta-hemihydrate gypsum, and the amount of the calcined phosphogypsum accounts for 45-55% of the total amount of the phosphogypsum.

[0008] Preferably, the slag is S95 grade blast furnace slag; and the cement is ordinary Portland cement with a P·O42.5.

[0009] The alkaline activator includes at least one of water glass, sodium sulfate, sodium hydroxide and calcium chloride.

[0010] More preferably, the alkali activator is water glass with a modulus of 1.2.

[0011] The foaming agent is a composite foaming agent, which is a mixture of aluminum powder, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate, with a mass ratio of 2:0.5-1.5:0.5-1.5.

[0012] Preferably, the phosphogypsum aerated concrete block further comprises 0.01-0.05 parts of basalt fiber with a length of 3-5 mm and a diameter of 10-15 μm.

[0013] Preferably, the modified titanium dioxide is prepared as follows: titanium dioxide is ultrasonically dispersed in an ethanol solution, a silane coupling agent and triethylamine are added for reaction, and the modified titanium dioxide is obtained by aging at room temperature, filtering and drying.

[0014] On the other hand, the present invention provides a method for preparing a phosphogypsum aerated concrete block, comprising the following steps: (1) taking part of the phosphogypsum and calcining it at high temperature to obtain β-hemihydrate gypsum, and aging it for later use; (2) mixing and stirring the remaining phosphogypsum, β-hemihydrate gypsum, cement, slag and quicklime to prepare a mixture; (3) dissolving the alkaline activator in water, adding the mixture, and stirring to obtain a mixed solution; (4) Adding a foaming agent, modified titanium dioxide and basalt fiber to the mixed liquid, stirring evenly to obtain a mixed slurry, and performing injection molding, pre-curing, autoclaving curing, cooling, demolding and cutting to obtain phosphogypsum-based aerated concrete blocks.

[0015] Preferably, in step (1), the calcination temperature of phosphogypsum is 180-220° C., and the calcination time is 2-3 h.

[0016] Preferably, step (1) further comprises: crushing the phosphogypsum and β-hemihydrate gypsum respectively; and ball-milling the slag and quicklime respectively.

[0017] More preferably, the particle size of the crushed phosphogypsum and β-hemihydrate gypsum is less than 0.5 mm; The ball-milled slag and quicklime are passed through a 300-350 mesh sieve.

[0018] Preferably, the specific surface area of ​​the slag is ≥400m 2 / kg, CaO content in quicklime ≥90%.

[0019] Preferably, in step (3), the pre-curing temperature is 50-60°C, the time is 3-4h, and the humidity is >90%.

[0020] Preferably, in step (3), the temperature of the autoclave is 180-200° C., the pressure is 1.2-1.4 MPa, and the time is 6-8 h.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention crushes or ball-mills the raw materials so that the components such as phosphogypsum, slag, cement and quicklime are fully contacted to generate hydration reaction, significantly improve the reaction efficiency, optimize the performance of the cementitious system, and improve the mechanical properties of the building blocks; introduces modified titanium dioxide and basalt fiber to further improve the mechanical properties and durability of the building blocks; uses a composite foaming agent to improve the foaming performance and foam stabilization performance of the foaming agent, reasonably regulates the porosity, reduces the thermal conductivity, and improves the thermal insulation performance of the building blocks.

[0022] 2. The present invention calcines part of the phosphogypsum to obtain hemihydrate gypsum, promotes the coagulation of the mixed material, and then makes aerated concrete with slag, cement, quicklime, foaming agent and other materials, with a compressive strength of 5.2-5.6MPa, thermal conductivity of 0.08-0.09W / mK, and dry density of 560-580g / m 3 , porosity 63-66%; and the phosphogypsum dosage 60-70%, which can not only consume a large amount of phosphogypsum, but also shorten the production cycle and reduce energy consumption. The mechanical properties of the resulting blocks have excellent comprehensive performance.

[0023] 3. The present invention uses phosphogypsum calcination pretreatment, composite foaming agent to stabilize foam and modified TiO 2 Operations such as uncontrolled pore structure and insufficient mechanical properties of phosphogypsum blocks solved the problems, achieved high-value utilization of solid waste, and had high economic and ecological benefits. DETAILED DESCRIPTION

[0024] Embodiment 1: The weight proportions of the components in this embodiment are: 25 parts of slag, 10 parts of cement, 65 parts of phosphogypsum, 6 parts of quicklime, 1 part of foaming agent, 1.5 parts of water glass, 6.5 parts of modified titanium dioxide, 0.03 parts of basalt fiber and 90 parts of water; wherein the foaming agent is a mixture of aluminum powder, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate, with a mass ratio of 2:1:1.

[0025] The preparation method of the phosphogypsum-based aerated concrete block in this embodiment is as follows: (1) taking half of the total amount of phosphogypsum, calcining at high temperature to obtain β-hemihydrate gypsum, and aging for later use; crushing the phosphogypsum and hemihydrate gypsum respectively, with a particle size of less than 0.5 mm; and ball-grinding the slag and quicklime respectively through a 300-350 mesh sieve; (2) mixing and stirring the treated phosphogypsum, hemihydrate gypsum, cement, slag and quicklime to obtain a mixture; dissolving water glass in water, mixing the mixture evenly, adding the mixture to the mixture and stirring the mixture evenly to obtain a mixed solution; (3) Add a foaming agent, modified titanium dioxide and basalt fiber to the mixed solution, stir evenly to obtain a slurry, pour the slurry into a mold to form, heat it to 55°C, and pre-cure it for 3.5 hours under a humidity condition of >90% to obtain a concrete block body, demold the aerated concrete block body and divide it, then place it in an autoclave, increase the pressure to 1.3 MPa and slowly increase the temperature to 190°C, steam cure for 7 hours, cool it to room temperature, demold it, and cut it to obtain a phosphogypsum-based aerated concrete block.

[0026] The modified titanium dioxide is prepared as follows: 10 g of titanium dioxide is ultrasonically dispersed in 40 ml of ethanol solution (the volume ratio of ethanol to water is 1:1) for 30 min, 0.5 g of KH570 and 1 ml of triethylamine are added, and the mixture is reacted at 90° C. for 2 h, aged at room temperature, filtered, washed, and dried to obtain the modified titanium dioxide.

[0027] Embodiment 2: The weight proportions of the components in this embodiment are: 20 parts of slag, 8 parts of cement, 60 parts of phosphogypsum, 4 parts of quicklime, 0.8 parts of foaming agent, 1 part of water glass, 5 parts of modified titanium dioxide, 0.01 parts of basalt fiber, and 80 parts of water; wherein the foaming agent is a mixture of aluminum powder, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate, with a mass ratio of 2:1:0.5.

[0028] The preparation method of the phosphogypsum aerated concrete block in this embodiment is as follows: (1) taking half of the total amount of phosphogypsum, calcining at high temperature to obtain β-hemihydrate gypsum, and aging for later use; crushing the phosphogypsum and hemihydrate gypsum respectively, with a particle size of less than 0.5 mm; and ball-grinding the slag and quicklime respectively through a 300-350 mesh sieve; (2) mixing and stirring the treated phosphogypsum, hemihydrate gypsum, cement, slag and quicklime to obtain a mixture; dissolving water glass in water, mixing the mixture evenly, adding the mixture to the mixture and stirring the mixture evenly to obtain a mixed solution; (3) Add a foaming agent, modified titanium dioxide and basalt fiber to the mixed solution, stir evenly to obtain a slurry, pour the slurry into a mold to form, heat it to 55°C, and pre-cure it for 3.5 hours under a humidity condition of >90% to obtain a concrete block body, demold the aerated concrete block body and divide it, then place it in an autoclave, increase the pressure to 1.3 MPa and slowly increase the temperature to 190°C, steam cure for 7 hours, cool it to room temperature, demold it, and cut it to obtain a phosphogypsum-based aerated concrete block.

[0029] The modified titanium dioxide is prepared as follows: 10 g of titanium dioxide is ultrasonically dispersed in 40 ml of ethanol solution (the volume ratio of ethanol to water is 1:1) for 30 min, 0.5 g of KH570 and 1 ml of triethylamine are added, and the mixture is reacted at 90° C. for 2 h, aged at room temperature, filtered, washed, and dried to obtain the modified titanium dioxide.

[0030] Embodiment 3: The weight proportions of the components in this embodiment are: 30 parts of slag, 12 parts of cement, 70 parts of phosphogypsum, 7 parts of quicklime, 1.2 parts of foaming agent, 2 parts of water glass, 8 parts of modified titanium dioxide, 0.05 parts of basalt fiber, and 100 parts of water; wherein the foaming agent is a mixture of aluminum powder, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate, with a mass ratio of 2:0.5:0.5.

[0031] The preparation method of the phosphogypsum aerated concrete block in this embodiment is as follows: (1) taking half of the total amount of phosphogypsum, calcining at high temperature to obtain β-hemihydrate gypsum, and aging for later use; crushing the phosphogypsum and hemihydrate gypsum respectively, with a particle size of less than 0.5 mm; ball-milling the slag and quicklime respectively, and then passing through a 300-350 mesh sieve; (2) mixing and stirring the treated phosphogypsum, hemihydrate gypsum, cement, slag and quicklime to obtain a mixture; dissolving water glass in water, mixing the mixture evenly, adding the mixture to the mixture and stirring the mixture evenly to obtain a mixed solution; (3) Add a foaming agent, modified titanium dioxide and basalt fiber to the mixed solution, stir evenly to obtain a slurry, pour the slurry into a mold to form, heat it to 55°C, and pre-cure it for 3.5 hours under a humidity condition of >90% to obtain a concrete block body, demold the aerated concrete block body and divide it, then place it in an autoclave, increase the pressure to 1.3 MPa and slowly increase the temperature to 190°C, steam cure for 7 hours, cool it to room temperature, demold it, and cut it to obtain a phosphogypsum-based aerated concrete block.

[0032] The modified titanium dioxide is prepared as follows: 10 g of titanium dioxide is ultrasonically dispersed in 40 ml of ethanol solution (the volume ratio of ethanol to water is 1:1) for 30 min, 0.5 g of KH570 and 1 ml of triethylamine are added, and the mixture is reacted at 90° C. for 2 h, aged at room temperature, filtered, washed, and dried to obtain the modified titanium dioxide.

[0033] Comparative Example 1: The composition of Comparative Example 1 is the same as that of Example 1. The difference between the composition and preparation method of the phosphogypsum-based aerated concrete block and Example 1 is that the foaming agent only includes aluminum powder and sodium dodecyl sulfate.

[0034] Comparative Example 2: The composition of Comparative Example 1 is the same as that of Example 1. The difference between the composition and preparation method of the phosphogypsum-based aerated concrete block and Example 1 is that the foaming agent only includes aluminum powder.

[0035] Comparative Example 3: The composition of Comparative Example 1 is the same as that of Example 1. The formula and production process of the phosphogypsum-based aerated concrete block differ from those of Example 1 in that it does not contain modified titanium dioxide.

[0036] Effect example: Table 1 shows the performance analysis results of the phosphogypsum-based aerated concrete blocks prepared by Examples 1 to 3 of the present invention and Comparative Examples 1 to 3.

[0037] Table 1

[0038] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A phosphogypsum-based aerated concrete block, characterized in that: The invention comprises the following raw materials in parts by weight: 20-30 parts of slag, 8-12 parts of cement, 60-70 parts of phosphogypsum, 4-7 parts of quicklime, 0.8-1.2 parts of foaming agent, 1-2 parts of alkali activator, 5-8 parts of modified titanium dioxide and 80-90 parts of water; the phosphogypsum is calcined at high temperature to generate β-hemihydrate gypsum, and the amount of the calcined phosphogypsum accounts for 45-55% of the total amount of the phosphogypsum.

2. A phosphogypsum-based aerated concrete block according to claim 1, characterized in that: The foaming agent is a composite foaming agent, which is a mixture of aluminum powder, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate, with a mass ratio of 2:0.5-1.5:0.5-1.

5.

3. The phosphogypsum-based aerated concrete block according to claim 1, characterized in that: The phosphogypsum aerated concrete building block also includes 0.01-0.05 parts of basalt fiber.

4. The phosphogypsum-based aerated concrete block according to claim 1, characterized in that: The modified titanium dioxide is prepared as follows: titanium dioxide is ultrasonically dispersed in an ethanol solution, a silane coupling agent and triethylamine are added for reaction, and the modified titanium dioxide is obtained by aging at room temperature, filtering and drying.

5. A method for preparing a phosphogypsum-based aerated concrete block according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) taking part of the phosphogypsum and calcining it at high temperature to obtain β-hemihydrate gypsum, and aging it for later use; (2) mixing and stirring the remaining phosphogypsum, β-hemihydrate gypsum, cement, slag and quicklime to prepare a mixture; (3) dissolving the alkaline activator in water, adding the mixture, and stirring to obtain a mixed solution; (4) Adding a foaming agent, modified titanium dioxide and basalt fiber to the mixed liquid, stirring evenly to obtain a mixed slurry, and performing injection molding, pre-curing, autoclaving curing, cooling, demolding and cutting to obtain phosphogypsum-based aerated concrete blocks.

6. The method for preparing a phosphogypsum-based aerated concrete block according to claim 4, characterized in that: In step (1), the calcination temperature of phosphogypsum is 180-220° C., and the calcination time is 2-3 hours.

7. The method for preparing a phosphogypsum aerated concrete block according to claim 4, characterized in that: Step (1) also includes crushing the remaining phosphogypsum and β-hemihydrate gypsum respectively; and ball-milling the slag and quicklime respectively.

8. The method for preparing a phosphogypsum-based aerated concrete block according to claim 7, characterized in that: The particle size of the crushed phosphogypsum and β-hemihydrate gypsum is less than 0.5 mm; The ball-milled slag and quicklime are passed through a 300-350 mesh sieve.

9. The method for preparing a phosphogypsum-based aerated concrete block according to claim 4, characterized in that: In step (3), the pre-curing temperature is 50-60°C, the time is 3-4h, and the humidity is >90%.

10. The method for preparing a phosphogypsum-based aerated concrete block according to claim 4, characterized in that: In step (3), the temperature of the autoclave is 180-200° C., the pressure is 1.2-1.4 MPa, and the time is 6-8 h.

Images