Calcium sulfate modified gel material and preparation method and application thereof

Abstract

The application discloses a calcium sulfate modified gel material and a preparation method and application thereof, and belongs to the technical field of fire safety and emergency materials. The material is composed of water glass, sodium bicarbonate, polyacrylamide and calcium sulfate, and the gel network structure is synergistically enhanced through the ionic crosslinking effect of Ca2+ and the salting-out effect of SO4 2- on the polymer chain. Experiments show that when the calcium sulfate addition amount is 1.0% of the total mass of the gel system, the cumulative drainage amount is 0g within 60 minutes, and the initial drainage time is more than 3600 seconds, which is much better than that of the unmodified gel (the drainage amount is 3.98g within 60 minutes, and the initial drainage time is 2287 seconds). Through the dual action mechanism of calcium sulfate, the water retention performance and structural stability of the gel material are significantly improved, the risk of free water precipitation causing high-temperature molten metal splashing and explosion is effectively avoided, and the gel material is suitable for emergency disposal of high-temperature molten metal leakage such as aluminum liquid and molten steel.

Description

Technical Field

[0001] This invention belongs to the field of fire safety and emergency materials technology, specifically relating to a calcium sulfate modified gel material, its preparation method and application, which is suitable for emergency response to high-temperature molten metal leakage accidents such as aluminum liquid and molten steel. Background Technology

[0002] Molten metal leaks pose a significant safety risk to the metallurgical and casting industries. Leaks of molten aluminum (approximately 660-700℃) or molten steel (above 1500℃) can ignite surrounding combustibles and, upon contact with water, trigger violent steam explosions, causing severe casualties and property damage. Currently used emergency response methods, such as sand containment and diversion trenches, generally suffer from operational inconvenience, low cooling efficiency, and ineffective shielding against heat radiation.

[0003] Water glass-sodium bicarbonate gel systems have attracted attention in high-temperature protection fields due to their three-dimensional network structure, which can bind a large amount of water and possess both water retention and thermal insulation properties. However, the water retention performance of traditional water glass-sodium bicarbonate gels still has considerable room for improvement. Under high-temperature environments, water still precipitates and evaporates relatively quickly, leading to a rapid decline in cooling and thermal insulation effects. Existing technologies have reported improving the water retention performance of gels by adding organic polymers such as polyacrylamide, but the introduction of organic polymers often increases the complexity and cost of the system, and the improvement in water retention performance is limited.

[0004] Recent studies on the Hofmeister effect have shown that different ions have specific effects on the aggregation state of macromolecular polymers in aqueous solutions. Calcium sulfate (CaSO4), as a widely available and inexpensive inorganic salt, releases Ca²⁺ from its aqueous solution, which can form ionic crosslinks with polar groups on polymer chains. Meanwhile, SO4²⁻, as a strong salting-out ion in the Hofmeister sequence, can promote polymer chain aggregation and network densification. However, there are currently no reports on using the synergistic effect of Ca²⁺ and SO4²⁻ in calcium sulfate to systematically regulate the water retention properties of water glass-polyacrylamide-sodium bicarbonate gel systems.

[0005] This invention is proposed based on the aforementioned technical problems. Summary of the Invention

[0006] I. Purpose of the Invention

[0007] This invention provides a calcium sulfate-modified gel material, its preparation method, and its applications. By adding a specific amount of calcium sulfate, the gel network structure is synergistically enhanced by the ionic crosslinking effect of Ca²⁺ and the salting-out effect of SO₄²⁻, significantly improving the water retention performance and structural stability of the gel material.

[0008] II. Technical Solution

[0009] (a) Calcium sulfate modified gel materials

[0010] It consists of the following components by mass fraction:

[0011] Water glass (WG, module 3.3) 10-14 <![CDATA[Sodium bicarbonate (NaHCO₃)]]> 2.6-3.6 Polyacrylamide (PAM) 0.1-0.4 <![CDATA[Calcium sulfate (CaSO4)]]> 0.3-1.5 water margin

[0012] Preferably, the amount of calcium sulfate added is 0.9% to 1.2%. More preferably, the amount of calcium sulfate added is 1.0%.

[0013] (II) The dual mechanism of action of calcium sulfate

[0014] (1) Ca²⁺ ion crosslinking effect: Ca²⁺ forms ion-dipole interaction with the amide groups on the polyacrylamide molecular chain, introducing additional physical crosslinking points and making the network structure more compact.

[0015] (2) SO4²⁻ Salting-out effect: SO4²⁻, as a strong salting-out ion in the Hofmeister sequence, promotes the aggregation and entanglement of polymer chains, further improving network density.

[0016] The two work together to build a denser and more stable gel network structure.

[0017] (III) Preparation method

[0018] (1) Dissolve polyacrylamide in water and stir until completely dissolved;

[0019] (2) Add calcium sulfate and stir for 5-15 minutes until evenly dispersed;

[0020] (3) Add water glass and stir well;

[0021] (4) Add sodium bicarbonate, stir for 1-3 minutes and let stand to form a gel (15-35℃).

[0022] (iv) Application methods

[0023] The aforementioned gel material is applied to the surface of the leaking, high-temperature molten metal. The water trapped inside the gel evaporates, absorbing heat and lowering the temperature. At the same time, the physical barrier effect of the gel network prevents the molten metal from flowing and spreading.

[0024] III. Beneficial Effects

[0025] (1) The water retention performance is significantly improved. The gel material with 1.0% calcium sulfate added has a cumulative drainage volume of 0g within 60 minutes and an initial drainage time of more than 3600 seconds, which is far better than the blank control group (drainage volume of 3.98g in 60 minutes and initial drainage time of 2287 seconds).

[0026] (2) Innovation of dual synergistic mechanism. The dual role mechanism of calcium sulfate in water glass-polyacrylamide-sodium bicarbonate gel system was revealed for the first time.

[0027] (3) Avoid secondary accidents. The drainage rate is significantly reduced, effectively preventing splashing and explosion when free water comes into contact with high-temperature molten metal.

[0028] (4) The raw materials are widely available and inexpensive. Calcium sulfate is a bulk industrial raw material and is suitable for large-scale production.

[0029] (5) Easy to operate. No complex equipment or process changes are required, making it easy for industrial production and on-site emergency use. Attached Figure Description

[0030] Figure 1 This is a line graph comparing the cumulative liquid discharge over 60 minutes between the calcium sulfate modified gel material and the unmodified gel material of this invention.

[0031] Figure 2 This is a graph showing the effect of different amounts of calcium sulfate added on the cumulative amount of liquid discharged from the gel material over 60 minutes.

[0032] Figure 3 This is a graph showing the effect of different amounts of calcium sulfate added on the initial drainage time of the gel material.

[0033] Figure 4 This is a schematic diagram illustrating the synergistic mechanism of Ca²⁺ ion crosslinking and SO₄²⁻ salting-out in the calcium sulfate modified gel material of this invention. Detailed Implementation

[0034] Example 1 (Calcium sulfate 1.0%)

[0035] Based on a total mass of 100g: 12g water glass, 3.4g sodium bicarbonate, 0.3g polyacrylamide, 1.0g calcium sulfate, and 83.3g water.

[0036] Performance: Cumulative drainage volume of 0g in 60 minutes, initial drainage time >3600s.

[0037] Example 2 (0.5% calcium sulfate)

[0038] Based on a total mass of 100g: 12g water glass, 3.4g sodium bicarbonate, 0.3g polyacrylamide, 0.5g calcium sulfate, and 83.8g water.

[0039] Performance: 2.76g of liquid discharged in 60 minutes, initial drainage time 584s.

[0040] Example 3 (Calcium sulfate 2.0%)

[0041] Based on a total mass of 100g: 12g water glass, 3.4g sodium bicarbonate, 0.3g polyacrylamide, 2.0g calcium sulfate, and 82.3g water.

[0042] Performance: 7.58g of liquid discharged in 60 minutes, with an initial drainage time of 33s.

[0043] Comparative Example 1 (Blank Group)

[0044] Based on a total mass of 100g: 12g water glass, 3.4g sodium bicarbonate, 0.3g polyacrylamide, and 84.3g water.

[0045] Performance: 3.98g of liquid discharged in 60 minutes, initial drainage time 2287s.

Claims

1. A calcium sulfate-modified gel material based on the synergistic effect of ionic crosslinking and salting-out, characterized in that, It consists of the following components by mass fraction: Water glass 10-14%, sodium bicarbonate 2.6-3.6%, polyacrylamide 0.1-0.4%, calcium sulfate 0.7-1.5%, balance water; In the gel system, the calcium sulfate forms ionic crosslinks with the amide groups on the polyacrylamide molecular chain through Ca²⁺, while the salting-out effect of SO₄²⁻ promotes the densification of the water glass condensation network. Both work synergistically to enhance the water retention performance of the gel.

2. The calcium sulfate-modified gel material according to claim 1, characterized in that, The amount of calcium sulfate added is 0.9% to 1.2%.

3. The calcium sulfate-modified gel material according to claim 1, characterized in that, The amount of calcium sulfate added is 1.0%.

4. The calcium sulfate-modified gel material according to claim 1, characterized in that, The modulus of the water glass is 3.0 to 3.

5.

5. A method for preparing the calcium sulfate modified gel material as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Dissolve polyacrylamide in water and stir until completely dissolved to obtain an aqueous solution of polyacrylamide; (2) Add calcium sulfate to the polyacrylamide aqueous solution and stir until it is evenly dispersed to obtain a mixed solution; (3) Add water glass to the mixed solution and stir until homogeneous; (4) Add sodium bicarbonate to the solution obtained in step (3), stir for 1-3 minutes and let stand to form a gel, and then obtain calcium sulfate modified gel material.

6. The preparation method according to claim 5, characterized in that, The stirring time in step (2) is 5~15 min and the stirring speed is 200~500 r / min.

7. The preparation method according to claim 5, characterized in that, The temperature for allowing the gel to stand in step (4) is 15~35℃.

8. The application of the calcium sulfate modified gel material as described in any one of claims 1-4 in emergency response to high-temperature molten metal leaks, characterized in that, The calcium sulfate-modified gel material is applied to the surface of the leaking high-temperature molten metal. The water trapped inside the gel evaporates and absorbs heat to cool the metal, while the physical barrier effect of the gel network prevents the molten metal from flowing and spreading.

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