High-water-content large-dosage titanium gypsum-based flow-state curing material as well as preparation method and application thereof

Abstract

The invention discloses a high-water-content large-dosage titanium gypsum-based flow-state curing material as well as a preparation method and application thereof, and belongs to the technical field of industrial solid waste resource utilization and building materials. According to the material, 50-70 parts of titanium gypsum, 15-30 parts of slag / fly ash and 5-15 parts of alkaline residue / carbide slag are used as main raw materials, and 0.1-1 part of xanthan gum is used as a flow state regulator as an auxiliary material. The material has high fluidity and self-compaction performance, the mechanical strength (7-day compressive strength is larger than or equal to 5 MPa) and the water stability (the water stability coefficient is larger than or equal to 0.7) of titanium gypsum can be remarkably improved, and meanwhile the leaching concentration of solidified heavy metal ions is lower than a standard value. The preparation method comprises the processes of raw material pretreatment, dry mixing, wet mixing and maintenance, is suitable for the fields of roadbed filling, building 3D printing, mine backfilling and the like, and realizes collaborative development of solid waste recycling and low-carbon building materials.

Description

Technical Field

[0001] The present invention relates to the field of industrial solid waste resource utilization and building materials technology, and specifically to a high-water-content fluidized solidifying material based on titanium gypsum, a preparation method thereof, and engineering applications thereof, which is suitable for large-volume filling and complex structure forming in civil engineering. Background Art

[0002] Titanium gypsum is an acidic waste residue produced during the production of titanium dioxide. Its main component is calcium sulfate dihydrate (CaSO4·2H2O). The traditional storage method not only occupies land, but also contains free acid, heavy metal ions (such as Fe 2+ , Al3+) easily seeps with rainwater and pollutes the environment. Existing titanium gypsum curing technologies often use cement-based materials, but these suffer from high dosages (20% to 40%), high costs, and poor fluidity, making them difficult to meet the requirements of fluid construction. Furthermore, the high porosity of titanium gypsum causes it to expand upon absorption of water, resulting in poor water stability, which restricts its engineering applications. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a high-water-content, high-volume titanium gypsum-based fluidized solidifying material with high fluidity and high compressive strength, which realizes high fluidity, high strength and long-term stability through synergistic stimulation of solid waste and rheological regulation, while reducing production costs and carbon emissions; another purpose of the present invention is to provide a method for preparing a high-water-content, high-volume titanium gypsum-based fluidized solidifying material; another purpose of the present invention is to provide an application of a high-water-content, high-volume titanium gypsum-based fluidized solidifying material.

[0004] Technical solution: The present invention provides a high-water-content, high-dosage titanium gypsum-based fluidized solidifying material, which comprises, by weight, 50 to 70 parts of titanium gypsum powder; 15 to 30 parts of slag or fly ash; 5 to 15 parts of alkali slag or carbide slag; and 0.1 to 1 part of xanthan gum.

[0005] Among them, titanium gypsum (50 parts to 70 parts) serves as the main gelling phase, providing a calcium sulfate skeleton; slag / fly ash (15 parts to 30 parts) provides activity, and the SiO2 and Al2O3 therein participate in the pozzolanic reaction; alkali slag / carbide slag (5 parts to 15 parts) provides Ca(OH)2, which stimulates the activity of slag and adjusts the pH; xanthan gum (0.1 parts to 1 part) forms a three-dimensional network structure through hydrogen bonding, thereby improving the thixotropy and water retention of the slurry.

[0006] Preferably, the pH value of the titanium gypsum powder is 6.5-7.5.

[0007] Preferably, the slag has a surface area of ​​≥450m 2 / kg of activated slag.

[0008] Preferably, the active SiO2+Al2O3 content in the fly ash is ≥65%.

[0009] On the other hand, the present invention provides a method for preparing the above-mentioned high-water-content, high-dosage titanium gypsum-based fluidized solidifying material, which is characterized in that titanium gypsum powder, slag / fly ash, and alkali slag / carbide slag are evenly mixed to obtain a dry mixture; water is added to the dry mixture and mixed until there is no obvious dry powder to obtain a wet mixture; xanthan gum solution is added to the wet mixture and mixed to obtain a fluidized solidifying material, that is, a high-water-content, high-dosage titanium gypsum-based fluidized solidifying material.

[0010] Furthermore, the preparation method of titanium gypsum powder is: drying original titanium gypsum with a moisture content of 20% to 30% to a moisture content of ≤5%, crushing and powdering the dried titanium gypsum, and adjusting the pH value to 6.5 to 7.5 to obtain titanium gypsum powder.

[0011] Furthermore, the slag is prepared by: 2 / kg blast furnace slag is ground to a specific surface area of ​​≥450m 2 / kg, after sieving, activated slag is obtained;

[0012] Furthermore, the fly ash is prepared by removing unburned carbon particles from the fly ash to ensure that the active SiO2+Al2O3 content is ≥65%.

[0013] On the other hand, the present invention provides an application of the above-mentioned high-water-content, high-dosage titanium gypsum-based fluidized solidifying material in the preparation of road base filling materials, building 3D printing materials or mine goaf backfill materials.

[0014] Principle of the invention: The titanium gypsum-based fluidized solidification material of the present invention is based on a multi-solid waste synergistic excitation system, wherein alkali slag / carbide slag is an alkaline waste slag containing a large amount of calcium oxide. After mixing with water, a saturated calcium hydroxide solution is generated, and the pH of the system rises to 12-13, forming a highly alkaline environment. The highly alkaline environment destroys the Si-O-Si and Al-O-Al bonds in the slag glass, thereby stimulating the active SiO2 and Al2O3 in the slag / fly ash to generate hydrated calcium silicate and hydrated calcium aluminate, whose nano-scale particles fill the gaps between the titanium gypsum crystals, significantly improving the density; at the same time, the hydrated calcium aluminate dissociates into aluminate ions, and the titanium gypsum releases sulfate ions. The aluminate and sulfate combine under the mediation of calcium ions to form needle-shaped calcium aluminate crystals, which greatly fill the pores of the original titanium gypsum; secondly, a small amount of dihydrated calcium sulfate in the titanium gypsum dissolves in an alkaline environment, releasing SO42- ions, which react with Ca 2+ The reaction generates ettringite, whose needle-like crystals penetrate the pores of the matrix to form a rigid skeleton.

[0015] AFt crystals and CSH gel intertwine to form a composite structure of "rigid skeleton + flexible gel," effectively resisting shrinkage stress and load deformation. Furthermore, xanthan gum molecular chains bind to free water through hydrogen bonds, forming a three-dimensional network. Under shear forces from stirring, the network temporarily dissociates, resulting in a low viscosity slurry and improved fluidity. After stagnant conditions, the network reconstructs, restoring viscosity and preventing segregation and exudation. The bound water content of xanthan gum is ≥30%, significantly slowing water evaporation and ensuring continuous hydration, thus preventing premature cracking.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The present invention realizes the utilization of high-content solid waste, wherein titanium gypsum accounts for ≥50%, and synergistically absorbs solid waste materials such as slag and calcium carbide slag, which reduces the cost by 40% to 50% compared with traditional cement-based materials; (2) The present invention has excellent rheological properties, with an initial fluidity of ≥180 mm and a fluidity retention rate of ≥90% after standing for 1 hour, which meets the requirements of long-distance pumping and complex structure printing, with an initial fluidity of 200 mm, and is suitable for pumping and 3D printing; (3) The present invention has good mechanical properties, with a compressive strength of ≥3 MPa at 3 days, which meets the demoulding requirements, ≥5 MPa at 7 days, which meets the roadbed filling standard, and ≥10 MPa at 28 days, which is better than C15 concrete, and its compression ratio reaches 0.25 to 0.3, which is significantly improved compared with pure titanium gypsum-based materials, and the impact resistance is improved by 50%; (4) The heavy metal leaching concentration of the present invention is lower than the limit value of the "Hazardous Waste Identification Standard" (GB 5085 3), and has good environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a process flow chart for preparing the same;

[0018] Figure 2 Comparison of unconfined strength under different formulations;

[0019] Figure 3 Microstructure of titanium gypsum-based fluidized solidifying materials. DETAILED DESCRIPTION

[0020] The titanium gypsum used in the present invention is acidic waste residue generated during the production of titanium dioxide by Jiangsu Taibai Group Co., Ltd., and its main component is calcium sulfate dihydrate (CaSO4·2H2O). Blast furnace slag was purchased from Henan Borun Casting Co., Ltd.; calcium carbide slag was purchased from Gongyi Yuanheng Water Purification Material Factory.

[0021] Example 1

[0022] (1) The original titanium gypsum with a moisture content of 25% is placed in a dryer and dried at 80±2°C until the moisture content is ≤5%. The dried titanium gypsum is then coarsely crushed using a ball mill and then graded through a 5mm pore size vibrating screen. The undersize material is reserved and the oversize material is returned for crushing. The crushed titanium gypsum is allowed to stand in a sealed bin for 48 hours to eliminate residual acidity, and the pH value is adjusted to 7. If necessary, 5% sodium carbonate solution is sprayed for neutralization.

[0023] (2) The specific surface area should be ≥400m 2 / kg blast furnace slag is ground twice in a vertical roller mill at a speed of 1800r / min to a specific surface area of ​​≥450m 2 / kg, and passed through a 200-mesh sieve to obtain activated slag.

[0024] (3) Carbide slag (Ca(OH)2≥60%) was processed by ball mill with a ball-to-material ratio of 2:1 and a grinding time of 30 min until D50≤20μm.

[0025] (4) Accurately weigh each component according to mass percentage: 60 parts of titanium gypsum, 25 parts of slag, 14 parts of calcium carbide slag, and 1 part of xanthan gum, with a water-to-solid ratio of 0.5.

[0026] (5) Titanium gypsum, slag and carbide slag are put into a double-shaft forced mixer and mixed at a low speed of 60 r / min for 5 minutes to ensure uniform mixing.

[0027] (6) Pour water into the mixer and start stirring at a low speed; slowly add the dry mix and stir for 3 minutes until there is no obvious dry powder; add the xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or reducing 0.1% xanthan gum or adjusting the water-solid ratio by ±0.05.

[0028] The microstructure of the titanium gypsum-based fluidized solidified material is as follows: Figure 3 As shown, its fluidity reaches 210mm and its 7-day compressive strength reaches 5.8MPa; the heavy metal Pb leaching concentration is 0.15mg / L, which is lower than the standard limit of 1.0mg / L.

[0029] Example 2

[0030] (1) The original titanium gypsum with a moisture content of 25% is placed in a dryer and dried at 80±2°C until the moisture content is ≤5%. The dried titanium gypsum is then coarsely crushed using a ball mill and then graded through a 5mm pore size vibrating screen. The undersize material is reserved and the oversize material is returned for crushing. The crushed titanium gypsum is allowed to stand in a sealed bin for 48 hours to eliminate residual acidity, and the pH value is adjusted to 7. If necessary, 5% sodium carbonate solution is sprayed for neutralization.

[0031] (2) The Class II fly ash is passed through an airflow separator to remove unburned carbon particles, ensuring that the active SiO2+Al2O3 content is ≥65%.

[0032] (3) Carbide slag (Ca(OH)2≥60%) was processed by ball mill with a ball-to-material ratio of 2:1 and a grinding time of 30 min until D50≤20μm.

[0033] (4) Accurately weigh each component according to mass percentage: 60 parts of titanium gypsum, 25 parts of fly ash, 14 parts of calcium carbide slag, and 1 part of xanthan gum, with a water-to-solid ratio of 0.5.

[0034] (5) Titanium gypsum, fly ash and calcium carbide slag are put into a double-shaft forced mixer and mixed at a low speed of 60 r / min for 5 minutes to ensure uniform mixing.

[0035] (6) Pour water into the mixer and start stirring at a low speed; slowly add the dry mix and stir for 3 minutes until there is no obvious dry powder; add the xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or subtracting 0.1 parts of xanthan gum or adjusting the water-solid ratio by ±0.05.

[0036] The prepared titanium gypsum-based fluidized solidifying material has a fluidity of 190 mm and a 7-day compressive strength of 0.78 MPa; the heavy metal Pb leaching concentration is 0.23 mg / L, which is lower than the standard limit of 1.0 mg / L.

[0037] Example 3

[0038] (1) The original titanium gypsum with a moisture content of 25% is placed in a dryer and dried at 80±2°C until the moisture content is ≤5%. The dried titanium gypsum is then coarsely crushed using a ball mill and then graded through a 5mm pore size vibrating screen. The undersize material is reserved and the oversize material is returned for crushing. The crushed titanium gypsum is allowed to stand in a sealed bin for 48 hours to eliminate residual acidity, and the pH value is adjusted to 7. If necessary, 5% sodium carbonate solution is sprayed for neutralization.

[0039] (2) The specific surface area should be ≥400m 2 / kg blast furnace slag is ground twice in a vertical roller mill at a speed of 1800r / min to a specific surface area of ​​≥450m 2 / kg, and passed through a 200-mesh sieve to obtain activated slag.

[0040] (3) Carbide slag (Ca(OH)2≥60%) was processed by ball mill with a ball-to-material ratio of 2:1 and a grinding time of 30 min until D50≤20μm.

[0041] (4) Accurately weigh each component according to mass percentage: 70 parts of titanium gypsum, 15 parts of slag, 14 parts of calcium carbide slag, and 1 part of xanthan gum, with a water-to-solid ratio of 0.5.

[0042] (5) Titanium gypsum, slag and carbide slag are put into a double-shaft forced mixer and mixed at a low speed of 60 r / min for 5 minutes to ensure uniform mixing.

[0043] (6) Pour water into the mixer and start stirring at a low speed; slowly add the dry mix and stir for 3 minutes until there is no obvious dry powder; add the xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or subtracting 0.1 parts of xanthan gum or adjusting the water-solid ratio by ±0.05.

[0044] The prepared titanium gypsum-based fluidized solidifying material has a fluidity of 200 mm and a 7-day compressive strength of 4.66 MPa; the heavy metal Pb leaching concentration is 0.17 mg / L, which is lower than the standard limit of 1.0 mg / L.

[0045] Example 4

[0046] (1) The original titanium gypsum with a moisture content of 25% is placed in a dryer and dried at 80±2°C until the moisture content is ≤5%. The dried titanium gypsum is then coarsely crushed using a ball mill and then graded through a 5mm pore size vibrating screen. The undersize material is reserved and the oversize material is returned for crushing. The crushed titanium gypsum is allowed to stand in a sealed bin for 48 hours to eliminate residual acidity, and the pH value is adjusted to 7. If necessary, 5% sodium carbonate solution is sprayed for neutralization.

[0047] (2) The specific surface area should be ≥400m 2 / kg blast furnace slag is ground twice in a vertical roller mill at a speed of 1800r / min to a specific surface area of ​​≥450m 2 / kg, and passed through a 200-mesh sieve to obtain activated slag.

[0048] (3) Carbide slag (Ca(OH)2≥60%) was processed by ball mill with a ball-to-material ratio of 2:1 and a grinding time of 30 min until D50≤20μm.

[0049] (4) Accurately weigh each component by mass percentage: 50 parts of titanium gypsum, 30 parts of slag, 15 parts of calcium carbide slag, 0.1 parts of xanthan gum, and a water-solid ratio of 0.5.

[0050] (5) Titanium gypsum, slag and carbide slag are put into a double-shaft forced mixer and mixed at a low speed of 60 r / min for 5 minutes to ensure uniform mixing.

[0051] (6) Pour water into the mixer and start stirring at a low speed; slowly add the dry mix and stir for 3 minutes until there is no obvious dry powder; add the xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or subtracting 0.1 parts of xanthan gum or adjusting the water-solid ratio by ±0.05.

[0052] The prepared titanium gypsum-based fluidized solidifying material has a fluidity of 210 mm and a 7-day compressive strength of 6.4 MPa; the heavy metal Pb leaching concentration is 0.19 mg / L, which is lower than the standard limit of 1.0 mg / L.

[0053] Comparative Example 1

[0054] (1) The original titanium gypsum with a moisture content of 25% is placed in a dryer and dried at 80±2°C until the moisture content is ≤5%. The dried titanium gypsum is then coarsely crushed using a ball mill and then graded through a 5mm pore size vibrating screen. The undersize material is reserved and the oversize material is returned for crushing. The crushed titanium gypsum is allowed to stand in a sealed bin for 48 hours to eliminate residual acidity, and the pH value is adjusted to 7. If necessary, 5% sodium carbonate solution is sprayed for neutralization.

[0055] (2) Carbide slag (Ca(OH)2≥60%) was processed by ball mill with a ball-to-material ratio of 2:1 and a grinding time of 30 min until D50≤20μm.

[0056] (3) Accurately weigh each component according to mass percentage: 60 parts of titanium gypsum, 14 parts of calcium carbide slag, 1 part of xanthan gum, and a water-solid ratio of 0.5.

[0057] (4) Titanium gypsum and calcium carbide slag are put into a double-shaft forced mixer and mixed at a low speed of 60 r / min for 5 minutes to ensure uniform mixing.

[0058] (5) Pour water into the mixer and start stirring at a low speed; slowly add the dry mix and stir for 3 minutes until there is no obvious dry powder; add the xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or subtracting 0.1 parts of xanthan gum or adjusting the water-solid ratio by ±0.05.

[0059] The prepared titanium gypsum-based fluidized solidifying material has a fluidity of 210 mm and a 7-day compressive strength of 0.56 MPa; the heavy metal Pb leaching concentration is 0.33 mg / L, which is lower than the standard limit of 1.0 mg / L.

[0060] Comparative Example 2

[0061] (1) The original titanium gypsum with a moisture content of 25% is placed in a dryer and dried at 80±2°C until the moisture content is ≤5%. The dried titanium gypsum is then coarsely crushed using a ball mill and then graded through a 5mm pore size vibrating screen. The undersize material is reserved and the oversize material is returned for crushing. The crushed titanium gypsum is allowed to stand in a sealed bin for 48 hours to eliminate residual acidity, and the pH value is adjusted to 7. If necessary, 5% sodium carbonate solution is sprayed for neutralization.

[0062] (2) Accurately weigh each component according to mass percentage: 60 parts of titanium gypsum, 1 part of xanthan gum, and a water-to-solid ratio of 0.5.

[0063] (3) Pour water into the mixer and start stirring at a low speed; slowly add titanium gypsum and stir for 3 minutes until there is no obvious dry powder; add xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or subtracting 0.1 parts of xanthan gum or adjusting the water-solid ratio by ±0.05.

[0064] The prepared titanium gypsum-based fluidized solidifying material has a fluidity of 210 mm and a 7-day compressive strength of 0.41 MPa; the heavy metal Pb leaching concentration is 0.31 mg / L, which is lower than the standard limit of 1.0 mg / L.

[0065] Comparative Example 3

[0066] (1) Pure CaSO4·2H2O was graded through a 5 mm pore size vibrating sieve, and the sieve residue was set aside.

[0067] (2) The specific surface area should be ≥400m 2 / kg blast furnace slag is ground twice in a vertical roller mill at a speed of 1800r / min to a specific surface area of ​​≥450m 2 / kg, and passed through a 200-mesh sieve to obtain activated slag.

[0068] (3) Carbide slag (Ca(OH)2≥60%) was processed by ball mill with a ball-to-material ratio of 2:1 and a grinding time of 30 min until D50≤20μm.

[0069] (4) Accurately weigh the following components by mass percentage: 60 parts of CaSO4·2H2O, 25 parts of slag, 14 parts of carbide slag, and 1 part of xanthan gum, with a water-to-solid ratio of 0.5.

[0070] (5) Place CaSO4·2H2O, slag, and carbide slag into a twin-shaft forced mixer and mix at a low speed of 60 r / min for 5 minutes to ensure uniform mixing.

[0071] (6) Pour water into the mixer and start stirring at a low speed; slowly add the dry mix and stir for 3 minutes until there is no obvious dry powder; add the xanthan gum solution and switch to high-speed stirring for 5 to 8 minutes until the slurry exhibits "silk-like" rheological properties; according to construction requirements, the fluidity can be fine-tuned by adding or reducing 0.1% xanthan gum or adjusting the water-solid ratio by ±0.05.

[0072] The prepared titanium gypsum-based fluidized solidifying material has a fluidity of 200 mm and a 7-day compressive strength of 4.75 MPa.

[0073] The present invention develops a high-water-content, high-dosage titanium gypsum-based fluidized solidifying material and its preparation method, which realizes the high-value resource utilization of industrial solid waste through the synergistic stimulation of multiple solid wastes. With titanium gypsum as the main body, a composite gelling system is constructed in collaboration with slag / fly ash, alkali slag / carbide slag, and xanthan gum is used to achieve shear-thinning rheological properties. This titanium gypsum-based fluidized solidifying material has high fluidity, with an initial fluidity of more than 180 mm; the 7d unconfined compressive strength is greater than 0.6 MPa, meeting the strength requirements of fluidized solidifying materials; and it has excellent environmental safety, with the heavy metal Pb / Cr leaching concentration far below the national standard limit;

[0074] This technology provides a high-performance, low-cost system solution for the large-scale utilization of industrial solid waste, and promotes the transformation of the building materials industry towards the coordinated development of "resources-environment-engineering".

Claims

1. A material, characterized in that Calculated by weight, it includes 50 to 70 parts of titanium gypsum powder; 15 to 30 parts of slag or fly ash; and 5 to 15 parts of alkali slag or calcium carbide slag. Xanthan gum: 0.1 to 1 part.

2. The material according to claim 1, characterized in that The pH value of the titanium gypsum powder is 6.5-7.

5.

3. The material according to claim 1, characterized in that The slag has a surface area of ​​≥450m 2 / kg of activated slag.

4. The material according to claim 1, characterized in that The active SiO2+Al2O3 content in the fly ash is ≥65%.

5. A method for preparing the material according to any one of claims 1 to 4, characterized in that: Titanium gypsum powder, slag / fly ash, and alkali slag / carbide slag are mixed evenly to obtain a dry mix; water is added to the dry mix and mixed until no obvious dry powder is left to obtain a wet mix; xanthan gum solution is added to the wet mix and mixed evenly to obtain a fluidized solidifying material, i.e., a high-water-content and high-dosage titanium gypsum-based fluidized solidifying material.

6. The method for preparing the material according to claim 5, characterized in that: The preparation method of titanium gypsum powder comprises the following steps: drying original titanium gypsum with a moisture content of 20% to 30%, crushing and powdering the dried titanium gypsum, and adjusting the pH value to 6.5 to 7.5 to obtain titanium gypsum powder.

7. The method for preparing the material according to claim 6, characterized in that: In the preparation of titanium gypsum powder, the original titanium gypsum with a moisture content of 20% to 30% is dried to a moisture content of ≤5% and then crushed and powdered.

8. The method for preparing the material according to claim 5, characterized in that: The preparation method of slag is as follows: 2 / kg blast furnace slag is ground to a specific surface area of ​​≥450m 2 / kg, after sieving, activated slag is obtained.

9. The method for preparing the material according to claim 5, characterized in that: The preparation method of fly ash is as follows: unburned carbon particles are removed from fly ash to ensure that the active SiO2+Al2O3 content is ≥65%.

10. Use of the material according to any one of claims 1 to 4 in the preparation of road base filling materials, building 3D printing materials or mine goaf backfill materials.

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