High-water-resistance phosphogypsum curing agent and preparation method thereof

Abstract

The invention relates to the technical field of ardealite preparation, and discloses a high-water-resistance ardealite curing agent which comprises 45%-55% of ardealite, 8%-14% of superfine slag powder, 17%-25% of Portland cement, 10%-15% of a cementing material, 1%-3% of an exciting agent, 0.5%-1.2% of polypropylene fibers and 0.4%-0.8% of a water reducing agent. The cementing material comprises the following components in percentage by weight: 44%-53% of phosphorus slag, 25%-33% of boiler ash and 23%-30% of coal ash. According to the high-water-resistance ardealite curing agent and the preparation method, the ardealite raw material is washed with water to remove impurities, soluble phosphate, fluoride and organic matters in the raw material are removed, free acid is neutralized with quick lime, the PH value is adjusted, the activity of heavy metal is reduced, the stability of ardealite is improved, and the toxic effect of ardealite on the environment is effectively reduced; the stability of the curing agent is guaranteed by mixing the superfine slag powder, the Portland cement and the cementing material, the water stability of the curing agent is improved by adding the water reducing agent, and the strength of the curing agent is further improved by adding the polypropylene fiber, so that the performance of the curing agent is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of phosphogypsum preparation, and specifically to a highly water-resistant phosphogypsum curing agent and a preparation method thereof. Background Art

[0002] Phosphogypsum mainly has two colors, grayish-black and grayish-white, with a particle diameter generally ranging from 5 to 50 μm and a crystal water content of 20% - 25%. Phosphogypsum is a solid waste generated in the wet-process phosphoric acid process. Its main component is calcium sulfate dihydrate, and the composition of phosphogypsum is relatively complex. In addition to calcium sulfate, there are unreacted phosphate rock, residual phosphoric acid, fluorides, acid-insoluble substances, organic matter, etc. The presence of fluorine and organic matter has the greatest impact on the resource utilization of phosphogypsum.

[0003] After retrieval, according to the invention patent with the Chinese patent publication number CN118108478A, a solid waste phosphogypsum subgrade soil curing agent and a preparation method thereof are disclosed. The phosphogypsum curing agent in this invention patent can effectively improve the strength of the curing agent by adding sodium silicate, sodium metaaluminate, and calcium chloride components. However, the water resistance of the phosphogypsum curing agent in this composition cannot be improved. Low water resistance will affect the structure of the curing agent and its stability in a humid environment. Therefore, the preparation of this phosphogypsum curing agent still needs to be further improved, so a highly water-resistant phosphogypsum curing agent and a preparation method thereof are proposed. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] Aiming at the deficiencies of the prior art, the present invention provides a highly water-resistant phosphogypsum curing agent and a preparation method thereof, which have the advantage of effectively improving the water resistance of the curing agent, and solve the problem that the existing phosphogypsum curing agent has low water resistance and cannot improve its stability in a humid environment in the above background art.

[0006] (II) Technical Solutions

[0007] To achieve the purpose of effectively improving the water resistance of the curing agent, the present invention provides the following technical solution: A highly water-resistant phosphogypsum curing agent, comprising raw materials in the following weight ratio: 45% - 55% phosphogypsum, 8% - 14% slag powder, 17% - 25% portland cement, 10% - 15% gelling material, 1% - 3% activator, 0.5% - 1.2% polypropylene fiber, and 0.4% - 0.8% water reducer. The gelling material includes 44% - 53% phosphorous slag, 25% - 33% boiler ash, and 23% - 30% fly ash in each weight ratio.

[0008] A preparation method of a highly water-resistant phosphogypsum curing agent, comprising the following steps:

[0009] S1. Raw material pretreatment: 1) Mix phosphogypsum and deionized water in a ratio of 1:4 by weight and stir for 30 min;

[0010] 2) Add 5% quicklime to the mixed slurry to adjust the pH value, and stir while heating in a water bath for 1 h;

[0011] 3) Centrifuge and filter, repeat the water washing process 3 times, and place in an oven to dry at 115 °C until constant weight;

[0012] 4) Put the dried paste into a ball mill to grind and crush for 20 min, and sieve through a 200-mesh sieve;

[0013] 5) Use an 80-μm sieve to remove lumps from the slag powder, and dilute the water reducer with water in a ratio of 1:10 for standby;

[0014] S2. Dry mixing: Select phosphogypsum, portland cement, and slag powder by weight and put them into a double-screw mixer, and stir at 40 - 70 rpm for 10 min until the color is evenly mixed;

[0015] S3. Wet mixing: Premix and stir the activator, water reducer, and deionized water evenly, and slowly add the premixed solution to the stirred material in the dry mixing process, and stir at 65 - 90 rpm for 15 min until a paste structure is formed;

[0016] S4. Batch feeding: Disperse the polypropylene fiber and divide it into three equal parts, and add it to the stirred paste in batches, and continue to stir at 25 - 40 rpm for 5 min waiting for discharging;

[0017] S5. Injection molding: Select a steel mold and place it on a vibrating table, pour the paste into the mold evenly and cover it with a plastic film for sealing, and vibrate and compact for 1 min;

[0018] S6. Curing treatment: 1) Pour the paste into a curing box, and leave it to stand for 24 h at a constant temperature and humidity of 20 - 25 °C and RH≥90% and then demold;

[0019] 2) Continue to add the solidified paste to an autoclave and cure it with saturated steam at 50 - 60 °C for 10 h;

[0020] 3) After curing and forming, place it in water at 20 °C and continue to cure for an age of 7 - 28 days, and obtain the phosphogypsum curing agent after discharging and drying.

[0021] Preferably, in step S1, add quicklime to adjust the pH value to 6 - 8, set the water bath heating temperature to 55 - 60 °C, repeat the centrifugal filtration and water washing treatment 3 times until the fluoride ion in the filtrate ≤ 50 mg / L and the conductivity < 500 μs / cm.

[0022] Preferably, in step S1, it is dried at 115°C, the water content of the paste block is controlled to be less than 2% - 3%, the paste block is ground to control the abrasive particle size of D50 ≤ 50μm, and the water reducing agent is a polycarboxylate water reducing agent.

[0023] Preferably, in step S2, after dry mixing and stirring until the colors are evenly mixed, the moisture content is detected and controlled at 0.8% - 1.5% using a moisture meter. In step S3, the activator is sodium sulfate, and after premixing and stirring, the water - binder ratio is controlled at 0.3 - 0.4.

[0024] Preferably, in step S4, three equal portions of polypropylene fibers are added to the wet - mixed paste in intervals of 2 minutes, and a small amount of quartz sand is added to the polypropylene fibers for dry - mixing and dispersion treatment.

[0025] Preferably, in step S5, the steel mold is a 40×40×160mm triple mold, the vibration frequency of the vibrating table is set at 40 - 50HZ. In step S6, the saturated steam is ultrasonic atomized water particles, the particle size is controlled at ≤10μm, and the heating rate of the autoclave is set at ≤10°C / h.

[0026] (III) Beneficial Effects

[0027] Compared with the prior art, the present invention provides a high - water - resistant phosphogypsum curing agent and a preparation method, having the following beneficial effects:

[0028] 1. For the high - water - resistant phosphogypsum curing agent and the preparation method, by washing and removing impurities from the phosphogypsum raw material, soluble phosphates, fluorides, and organic substances in the raw material are removed, and quicklime is used to neutralize free acids, adjust the PH value and reduce the activity of heavy metals, thereby improving the stability of phosphogypsum and effectively reducing the toxic effect of phosphogypsum on the environment.

[0029] 2. For the high - water - resistant phosphogypsum curing agent and the preparation method, by selecting blast furnace slag powder, portland cement, and cementitious materials for mixing, the stability of the curing agent components is ensured, a water - reducing agent is added to improve the water - stability of the curing agent, and polypropylene fibers are added to further improve the strength of the curing agent, thereby effectively improving the performance of the curing agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the preparation method of the high - water - resistant phosphogypsum curing agent of the present invention;

[0031] Figure 2 It is a schematic diagram of the performance of the standard phosphogypsum curing agent of the present invention;

[0032] Figure 3 It is a schematic diagram of the performance of the high - water - resistant phosphogypsum curing agent with different components of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Embodiment 1

[0035] In this embodiment, 47% of phosphogypsum, 14% of slag powder, 25% of portland cement, 12% of cementitious material, 1% of activator, 0.6% of polypropylene fiber, and 0.4% of water reducer are selected according to the weight ratio.

[0036] According to the selected preparation raw materials, the specific preparation process includes:

[0037] L1. Dry mixing treatment: Select 47% of phosphogypsum, 25% of portland cement, and 14% of slag powder and put them into a double - helix mixer, stir at 40 - 70 rpm for 10 min until the color is evenly mixed, and use a moisture meter to detect and control the moisture content at 0.8% - 1.5%;

[0038] L2. Wet mixing treatment: Premix and stir 1% of activator, 0.4% of water reducer, and deionized water evenly. After premixing and stirring, control the water - binder ratio to be 0.3 - 0.4. Slowly add the premixed solution to the stirred material obtained from the dry mixing treatment, and stir at 65 - 90 rpm for 15 min until a paste - like structure is formed;

[0039] L3. Batch feeding: Disperse 0.6% of polypropylene fiber and divide it into three equal parts, and add it to the stirred paste in batches at an interval of 2 min, and continue to stir at 25 - 40 rpm for 5 min waiting for discharging;

[0040] L4. Injection molding: Select a steel mold of a 40×40×160 mm triple mold and place it on a vibrating table. Set the vibration frequency of the vibrating table to 40 - 50 HZ. Pour the paste evenly into the mold and cover it with a plastic film for sealing, and vibrate it densely for 1 min;

[0041] L5. Curing treatment: 1) Pour the paste into a curing box, and let it stand for 24 h under the constant temperature and humidity conditions of 20 - 25°C and RH≥90% and then demold;

[0042] 2) Continue to add the solidified paste into an autoclave, and cure it with saturated steam at 50 - 60°C for 10 h. The saturated steam is ultrasonic atomized water particles with a particle size ≤10 μm, and set the heating rate of the autoclave ≤10°C / h;

[0043] 3) After curing and forming, put it into water at 20°C and continue to cure for an age of 7 - 28 days, and obtain the phosphogypsum curing agent after discharging and drying.

[0044] Example 2

[0045] In this example, 50% of phosphogypsum, 12% of slag powder, 22% of portland cement, 13% of cementitious material, 1.5% of activator, 0.8% of polypropylene fiber and 0.7% of water reducer are selected according to the weight ratio.

[0046] According to the selected preparation raw materials, the specific preparation process includes:

[0047] L1. Dry mixing treatment: Select 50% of phosphogypsum, 22% of portland cement and 12% of slag powder and put them into a double - helix mixer, stir at 40 - 70 rpm for 10 min until the color is evenly mixed, and use a moisture meter to detect and control the moisture content at 0.8% - 1.5%;

[0048] L2. Wet mixing treatment; Premix and stir evenly 1.5% of activator, 0.7% of water reducer and deionized water. After premix and stir, control the water - binder ratio at 0.3 - 0.4, and slowly add the premixed solution to the stirred material in the dry mixing treatment, and stir at 65 - 90 rpm for 15 min until a paste - like structure is formed;

[0049] L3. Batch feeding: Disperse 0.8% of polypropylene fiber and divide it into three equal parts, and add it to the stirred paste in batches at an interval of 2 min, and continue to stir at 25 - 40 rpm for 5 min waiting for discharging;

[0050] L4. Injection molding: Select a steel mold of a 40×40×160 mm triple mold and place it on a vibrating table, set the vibration frequency of the vibrating table at 40 - 50 HZ, pour the paste evenly into the mold and cover it with a plastic film for sealing, and vibrate and compact for 1 min;

[0051] L5. Curing treatment: 1) Pour the paste into a curing box, and leave it to stand for 24 h under the condition of constant temperature and humidity at 20 - 25℃ and RH≥90% and then demold;

[0052] 2) Continue to add the solidified paste into an autoclave, and cure it with saturated steam at 50 - 60℃ for 10 h. The saturated steam is ultrasonic atomized water particles, control the particle size ≤10μm, and set the heating rate of the autoclave ≤10℃ / h;

[0053] 3) After curing and forming, put it into water at 20℃ and continue to cure for an age of 7 - 28 days, and obtain the phosphogypsum curing agent after discharging and drying.

[0054] Example 3

[0055] In this example, 54% of phosphogypsum, 8% of slag powder, 20% of portland cement, 14% of cementitious material, 2% of activator, 1.2% of polypropylene fiber and 0.8% of water reducer are selected according to the weight ratio.

[0056] According to the selected raw materials for preparation, the specific preparation process includes:

[0057] L1. Dry mixing treatment: Select 54% phosphogypsum, 20% portland cement, and 8% slag powder and put them into a double-screw mixer. Stir at 40 - 70 rpm for 10 min until the color is evenly mixed. Use a moisture meter to detect and control the moisture content at 0.8% - 1.5%;

[0058] L2. Wet mixing treatment: Premix and stir evenly 2% activator, 0.8% water reducer, and deionized water. After premixing and stirring, control the water-binder ratio at 0.3 - 0.4. Slowly add the premixed solution to the stirred material obtained from the dry mixing treatment, and stir at 65 - 90 rpm for 15 min until a paste-like structure is formed;

[0059] L3. Batch feeding: Disperse 1.2% polypropylene fiber and divide it into three equal parts. Add it to the stirred paste in batches at an interval of 2 min, and continue to stir at 25 - 40 rpm for 5 min waiting for discharging;

[0060] L4. Injection molding: Select a steel mold of a 40×40×160 mm triple mold and place it on a vibrating table. Set the vibration frequency of the vibrating table at 40 - 50 HZ. Pour the paste into the mold evenly and cover it with a plastic film for sealing, and vibrate and compact for 1 min;

[0061] L5. Curing treatment: 1) Pour the paste into a curing box, and let it stand for 24 h under the constant temperature and humidity conditions of 20 - 25°C and RH≥90%, and then demold;

[0062] 2) Continue to add the solidified paste into an autoclave, and cure it with saturated steam at 50 - 60°C for 10 h. The saturated steam is ultrasonic atomized water particles, control the particle size ≤10 μm, and set the heating rate of the autoclave ≤10°C / h;

[0063] 3) After curing and forming, put it into water at 20°C and continue to cure for an age of 7 - 28 days. After discharging and drying, a phosphogypsum curing agent is obtained.

[0064] Combined with Figure 2 and Figure 3 As shown, in Example 3, by selecting various proportion ratios of phosphogypsum, slag powder, portland cement, gelling material, activator, polypropylene fiber, and water reducer, a higher water resistance characteristic of the curing agent can be achieved.

[0065] In summary, for the high water-resistant phosphogypsum curing agent and its preparation method, impurities are removed from the phosphogypsum raw material through water washing to remove soluble phosphates, fluorides and organic substances in the raw material, and quicklime is used to neutralize free acid, adjust the pH value and reduce the activity of heavy metals, thereby improving the stability of phosphogypsum, effectively reducing the toxic effect of phosphogypsum on the environment. By selecting slag powder, Portland cement and gelling materials for mixing, the stability of the curing agent components is ensured, and a water reducer is added to improve the water stability of the curing agent. At the same time, polypropylene fibers are added to further improve the strength of the curing agent, thereby effectively improving the performance of the curing agent.

[0066] All related modules involved in this system are hardware system modules or functional modules that combine computer software programs or protocols in the prior art with hardware. The computer software programs or protocols themselves involved in this functional module are all well-known technologies to those skilled in the art, and they are not the improvements of this system. The improvement of this system lies in the interaction relationship or connection relationship between each module, that is, the overall structure of the system is improved to solve the corresponding technical problems to be solved by this system.

[0067] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highly water-resistant phosphogypsum curing agent, comprising raw materials in the following weight parts ratio: 45% - 55% phosphogypsum, 8% - 14% slag powder, 17% - 25% portland cement, 10% - 15% cementitious material, 1% - 3% activator, 0.5% - 1.2% polypropylene fiber, and 0.4% - 0.8% water reducer, wherein the cementitious material comprises 44% - 53% phosphorous slag, 25% - 33% boiler ash, and 23% - 30% fly ash in the weight ratio of each component.

2. A preparation method of a highly water-resistant phosphogypsum curing agent, characterized in that, Comprising the following steps: S1. Raw material pretreatment: 1) Mix phosphogypsum and deionized water in a ratio of 1:4 and stir for 30 min; 2) Add 5% quicklime to the mixed slurry to adjust the pH value, and stir with water bath heating for 1 h; 3) Centrifuge and filter, and repeat the water washing 3 times, then put it into an oven and dry at 115 °C until constant weight; 4) Put the dried paste into a ball mill and grind and crush for 20 min, and sieve through a 200-mesh sieve; 5) Use an 80-μm sieve to remove caking from the slag powder, and dilute the water reducer with water in a ratio of 1:10 for standby; S2. Dry mixing treatment: Select phosphogypsum, portland cement, and slag powder according to the weight parts and put them into a double-screw mixer, and stir at 40 - 70 rpm for 10 min until the color is evenly mixed; S3. Wet mixing treatment; Premix and stir the activator, water reducer, and deionized water evenly, and slowly add the premixed solution to the stirred material in the dry mixing treatment, and stir at 65 - 90 rpm for 15 min until a paste structure is formed; S4. Batch feeding: Disperse the polypropylene fiber and divide it into three equal parts, and add it to the stirred paste in batches, and continue to stir at 25 - 40 rpm for 5 min and wait for discharging; S5. Injection molding: Select a steel mold and place it on a vibrating table, pour the paste into the mold evenly and cover it with a plastic film for sealing, and vibrate and compact for 1 min; S6. Curing treatment: 1) Pour the paste into a curing box, and let it stand for 24 h under the constant temperature and humidity conditions of 20 - 25 °C and RH ≥ 90%, and then demold; 2) Continue to add the solidified paste into an autoclave, and cure it with saturated steam at 50 - 60 °C for 10 h; 3) After curing and forming, put it into water at 20 °C and continue to cure for 7 - 28 days of age, and obtain the phosphogypsum curing agent after discharging and drying.

3. A method for preparing a highly water-resistant phosphogypsum curing agent according to claim 2, characterized in that, In step S1, add quicklime to adjust the pH value to 6 - 8, set the water bath heating temperature to 55 - 60 °C, repeat the centrifugal filtration and water washing treatment 3 times until the fluoride ion in the filtrate ≤ 50 mg / L and the conductivity < 500 μs / cm.

4. A method for preparing a highly water-resistant phosphogypsum curing agent according to claim 2, characterized in that, In step S1, perform drying treatment at 115 °C, control the moisture content of the paste to be less than 2% - 3%, control the abrasive particle size of the paste grinding treatment to be D50 ≤ 50 μm, and the water reducer is a polycarboxylate-based water reducer.

5. The preparation method of a highly water-resistant phosphogypsum curing agent according to claim 2, characterized in that, In step S2, after dry mixing and stirring until the color is evenly mixed, use a moisture meter to detect and control the moisture content to be 0.8% - 1.5%. In step S3, the activator is sodium sulfate, and after premixing and stirring, control the water-binder ratio to be 0.3 - 0.

4.

6. The preparation method of a highly water-resistant phosphogypsum curing agent according to claim 2, characterized in that, In step S4, add the three equal parts of polypropylene fiber to the wet-mixed paste in batches at an interval of 2 min, and add a small amount of quartz sand to the polypropylene fiber for dry mixing and dispersion treatment.

7. A preparation method of a highly water-resistant phosphogypsum curing agent according to claim 2, characterized in that, The steel die mold described in step S5 is a triple mold of 40×40×160 mm. The vibration frequency of the vibrating table is set to 40 - 50 HZ. In step S6, the saturated steam is ultrasonic atomized water particles with a controlled particle size of ≤10 μm, and the heating rate of the autoclave is set to ≤10 °C / h.

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