Anti-blocking agent as well as preparation method and application thereof

Abstract

The invention discloses an anti-blocking agent as well as a preparation method and application thereof. The anti-blocking agent is prepared from the following components in percentage by mass: 70-75% of talcum powder, 13-18% of stearic acid, 4-7% of fumed silica and 3-5% of polyethylene glycol. The raw materials are easy to obtain and low in cost; the prepared anti-caking agent is suitable for different weather conditions in south and north, and can effectively inhibit caking of the soil conditioner. Tests show that after the anti-caking agent is added, the caking rate of a sample within 30 days is obviously reduced to 4.8% from 43.2% (blank control). In addition, the product is convenient to apply, simple to operate and small in addition amount.

Description

Technical Field

[0001] This invention relates to the field of anti-caking technology for powder materials, and in particular to an anti-caking agent, its preparation method, and its application. Background Technology

[0002] Phosphogypsum is a byproduct of the wet-process phosphoric acid production, and it is one of the largest solid wastes emitted by the chemical industry. Its main component is calcium sulfate dihydrate. The composition of phosphogypsum is complex, containing not only calcium sulfate but also incompletely decomposed phosphate rock, residual phosphoric acid, fluorides, acid-insoluble substances, and organic matter. The presence of fluorine and organic matter has the greatest impact on the resource utilization of phosphogypsum. The indiscriminate dumping and accumulation of phosphogypsum severely damages the ecological environment, polluting groundwater resources and wasting land resources.

[0003] Agricultural activities rely heavily on chemical fertilizers, but long-term application can lead to soil degradation and even loss of cultivability, necessitating soil improvement. Phosphogypsum can effectively regulate soil pH, replenish nutrients such as sulfur and calcium, improve soil structure, and enhance soil biological activity and salt tolerance. To achieve the reuse of waste phosphogypsum, it is currently being gradually applied to the improvement and remediation of degraded soils.

[0004] In recent years, phosphogypsum has received widespread attention as a soil conditioner. However, due to its inherent properties, it still faces many challenges in practical applications. For example, phosphogypsum-based soil conditioners are prone to caking under the influence of factors such as air humidity (relative humidity 60-85% in summer), temperature, and storage conditions. The caking material must undergo further crushing and screening, which not only increases costs but also causes inconvenience in production and application. Therefore, there is an urgent need to develop a highly efficient anti-caking agent suitable for phosphogypsum soil conditioners. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to provide an anti-caking agent, its preparation method, and its application, thereby solving the problem of easy caking in existing phosphogypsum soil conditioners.

[0006] The objective of this invention is achieved through the following technical solution: An anti-caking agent is prepared from the following components in weight percentage: 70-75% talc, 13-18% stearic acid, 4-7% fumed silica and 3-5% polyethylene glycol.

[0007] In this invention, talc is used as a carrier for the anti-caking agent, stearic acid is used as a modifier to improve the hydrophobicity and anti-adhesion properties of the anti-caking agent, fumed silica has an anti-agglomeration effect and can improve the flowability of the powder, and polyethylene glycol is used to enhance the adhesion of the anti-caking agent to the powder surface.

[0008] Preferably, the number average molecular weight of the polyethylene glycol is 8000.

[0009] Preferably, the fineness of the talc powder is 1250 mesh.

[0010] The anti-caking agent prepared by this invention is a white, ultrafine powder with a uniform appearance and no visible lumps. Its hydrophobicity is determined to be no less than 94%, and its bulk density is 0.75~0.85 g / cm³. 3 The particle size distribution D90 ≤ 30 μm remains stable below 200℃ with no obvious decomposition. This combination of physical properties makes it well-matched with powdered soil conditioners in terms of particle size, density, and thermal stability, facilitating uniform blending.

[0011] The specific testing principle, instruments and reagents used, testing steps, and calculation formula for the hydrophobicity of the anti-caking agent are as follows: I. Principle The hydrophobicity of powder is characterized by measuring the proportion of powder that is not wetted by water after contact with water; the higher the hydrophobicity, the stronger the powder's resistance to moisture absorption and agglomeration.

[0012] II. Reagents and Instruments 1. Reagent: Deionized water 2. Instruments: Electronic balance (accuracy 0.001g), standard sieve (20 mesh), beaker (250mL), vacuum filtration device, drying oven. III. Test Steps 1. Sample pretreatment Take the modified powder to be tested (such as phosphogypsum powder with added anti-caking agent), dry it in an oven at 105±2℃ to constant weight, cool it to room temperature, and then pass it through a 20-mesh sieve to remove large particles and lumps.

[0013] 2. Weighing and mixing Accurately weigh the pretreated powder sample m1 (accurate to 0.001g) and place it in a 250mL beaker; add 100mL of deionized water and stir at a constant speed with a glass rod for 3min to ensure that the powder and water are fully in contact.

[0014] 3. Solid-liquid separation Pour the mixture into a funnel lined with quantitative filter paper, turn on vacuum filtration until the filtrate drips completely; collect the unwetted powder on the filter paper.

[0015] 4. Drying and Weighing Place the filter paper containing the unwetted powder into an oven and dry it at 105±2℃ to constant weight. After cooling to room temperature, accurately weigh the total mass m2 of the unwetted powder and the filter paper; at the same time, weigh the mass m0 of the filter paper.

[0016] IV. Calculation Formula Hydrophobicity (%) = (m2 - m0) / m1 × 100% Where: m1——mass of the pretreated powder sample, in g; m2 — Total mass of unwetted powder and filter paper, in grams; m0 — the mass of the filter paper, in grams.

[0017] The preparation method of the above-mentioned anti-caking agent includes the following steps: talc powder, stearic acid, fumed silica and polyethylene glycol weighed according to the formula ratio are mixed, heated to 105~115℃ and stirred for modification, and after the modification is completed, the mixture is cooled and discharged.

[0018] Preferably, the stirring speed is 1000~1200 r / min.

[0019] Preferably, the stirring time for modification is 35-45 minutes.

[0020] Preferably, the material is discharged after the modification is completed and the temperature is reduced to ≤35℃.

[0021] In this invention, to meet the mixing requirements of ultrafine powder, the stirring rate is set to 1000~1200 r / min. Furthermore, to avoid high-temperature moisture absorption, the discharge temperature should not be too high, generally not exceeding 35℃.

[0022] The above-mentioned anti-caking agent is used as an anti-caking agent for phosphogypsum soil conditioner.

[0023] Preferably, the application includes the following steps: mixing the phosphogypsum soil conditioner and the anti-caking agent evenly.

[0024] Preferably, the amount of the anti-caking agent added to the phosphogypsum soil conditioner is x. When the moisture content of the phosphogypsum soil conditioner is <8%, 0.15wt%≤x<0.2wt%; when the moisture content of the phosphogypsum soil conditioner is 8~12%, 0.2wt%≤x<0.3wt%; when the moisture content of the phosphogypsum soil conditioner is >12%, 0.3wt%≤x≤0.35wt%.

[0025] Compared with the prior art, the beneficial effects of the present invention include: (1) The raw materials for preparation of this invention are easy to obtain and the cost is low; the prepared anti-caking agent can be applied to both southern and northern climates, effectively preventing soil conditioner from caking and hardening. At the same time, it is convenient to use, simple to operate and requires a small amount.

[0026] (2) The anti-caking agent prepared in this invention targets the characteristics of powdered phosphogypsum soil conditioner, namely "large specific surface area and strong hygroscopicity". Through the triple synergistic effect of "physical isolation of ultrafine carrier + hydrophobic modification of stearic acid + anti-agglomeration of fumed silica", it successfully reduced the caking rate from 43.2% to 4.8% in 30 days. At the same time, it optimized the powder flowability and dispersibility, without affecting the fertilizer effect and controlling the addition cost. This solution does not require modification of the existing production line, the addition method is simple and easy to operate, and it is suitable for high humidity storage scenarios. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 An anti-caking agent is prepared from the following components in weight percentage: 70% talc, 18% stearic acid, 7% fumed silica and 5% PEG-8000.

[0029] The preparation method of the above-mentioned anti-caking agent includes the following steps: talc powder, stearic acid, fumed silica and polyethylene glycol weighed according to the formula ratio are mixed, heated to 105°C and stirred for 35 min for modification, and after the modification is completed, the temperature is lowered to 35°C and the material is discharged.

[0030] Example 2 An anti-caking agent is prepared from the following components in weight percentages: 72% talc, 16% stearic acid, 7% fumed silica and 5% PEG-8000.

[0031] The preparation method of the above-mentioned anti-caking agent includes the following steps: talc powder, stearic acid, fumed silica and polyethylene glycol weighed according to the formula ratio are mixed, heated to 115°C and stirred for 45 min for modification, and after modification, the temperature is lowered to 35°C and the material is discharged.

[0032] Example 3 An anti-caking agent is prepared from the following components in weight percentages: 78% talc, 14% stearic acid, 4% fumed silica and 4% PEG-8000.

[0033] The preparation method of the above-mentioned anti-caking agent includes the following steps: talc powder, stearic acid, fumed silica and polyethylene glycol weighed according to the formula ratio are mixed, heated to 105°C and stirred for 40 min for modification, and after modification, the temperature is lowered to 35°C and the material is discharged.

[0034] Comparative Example 1 Compared with Example 1, the only difference is that it does not contain PEG-8000, and the remaining components, talc, stearic acid, and fumed silica, are adjusted to a total of 100% according to their relative proportions in Example 1.

[0035] Comparative Example 2 Compared with Example 1, the only difference is that stearic acid is not included, and the remaining components, talc, PEG-8000, and fumed silica, are adjusted to a total of 100% according to their relative proportions in Example 1.

[0036] Comparative Example 3 Compared with Example 1, the only difference is that it does not contain fumed silica, and the remaining components, talc, stearic acid, and PEG-8000, are adjusted to a total of 100% according to their relative proportions in Example 1.

[0037] Anti-caking experiment Commercially available phosphogypsum soil conditioner (purchased from a phosphogypsum soil conditioner manufacturer in Hubei Province, with a moisture content >12%) was uniformly mixed with the anti-caking agents prepared in Examples 1-3 and Comparative Examples 1-3 at a mass ratio of 0.3 wt%, resulting in a total of 6 sample groups. A blank control group was also included, without the addition of anti-caking agent. Each sample group was placed in woven bags (net weight 50 kg per bag) and stored in the same storage environment (temperature 25±5℃, relative humidity 75±5%) for 30 days. During storage, samples were taken periodically, and the degree of caking was tested using the same method.

[0038] After the anti-caking agent prepared in Example 1 was mixed evenly with the phosphogypsum soil conditioner, the angle of repose of the resulting mixed powder was 28°, while the angle of repose of the blank control group without the anti-caking agent was 48°. The results indicate that adding the anti-caking agent significantly improved the powder's flowability, helping to reduce "bridging" during storage, thus making it more suitable for automated packaging and mechanized field application. Furthermore, the mixed powder obtained in Example 1 could be uniformly dispersed in water within 30 seconds, while the blank control group easily agglomerated and settled. This suggests that the anti-caking agent helps improve the dispersibility of the phosphogypsum soil conditioner in water, thereby promoting uniform fertilization in the field.

[0039] The statistical results of the anti-caking experiment are shown in Table 1.

[0040] Table 1 Results of Anti-caking Experiment

[0041] Referring to Table 1, we can conclude that: (1) Comparison of anti-caking effects of Examples 1-3: Example 1 showed the best anti-caking performance, with a caking rate of only 4.8% after 30 days; the caking rates of Examples 2 and 3 were slightly higher than those of Example 1, but both were much lower than those of the blank group and the comparative example. This indicates that the formulation and process parameters of 70% talc powder, 18% stearic acid, modification temperature of 105℃, and stirring time of 35min have the best anti-caking effect on phosphogypsum soil conditioner.

[0042] (2) Comparative analysis of the comparative example and Example 1 Comparative Example 1, which does not contain PEG-8000, showed an agglomeration rate of 18.3% after 30 days, indicating that PEG-8000 can effectively improve the film-forming and dispersible properties of the anti-caking agent and reduce the adhesion between powder particles.

[0043] Comparative Example 2, which does not contain stearic acid, had an agglomeration rate of 31.5% after 30 days, close to that of the blank group, indicating that stearic acid is the core component for reducing powder surface tension and inhibiting agglomeration.

[0044] Comparative Example 3, which does not contain fumed silica, had an agglomeration rate of 24.2% after 30 days. This indicates that fumed silica can hinder the contact and aggregation between particles through steric hindrance, thus helping to improve the anti-agglomeration effect.

[0045] (3) Overall conclusion: The anti-caking agent formulation of the present invention is scientific, and the components work synergistically to significantly reduce the caking rate of phosphogypsum soil conditioner in high humidity storage environment, while improving the powder flowability and dispersibility in water; compared with the comparative example which lacks a single key component, the complete formulation has significant advantages in anti-caking performance.

[0046] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An anti-caking agent, characterized in that, It is prepared from the following components by mass percentage: 70-75% talc, 13-18% stearic acid, 4-7% fumed silica and 3-5% polyethylene glycol.

2. The anti-caking agent according to claim 1, characterized in that, The number-average molecular weight of the polyethylene glycol is 8000.

3. The anti-caking agent according to claim 1, characterized in that, The fineness of the talc powder is 1250 mesh.

4. A method for preparing the anti-caking agent according to any one of claims 1 to 3, characterized in that, The process includes the following steps: talc powder, stearic acid, fumed silica and polyethylene glycol weighed according to the formula ratio are mixed, heated to 105~115℃ and stirred for modification, and then cooled and discharged after modification.

5. The method for preparing the anti-caking agent according to claim 4, characterized in that, The stirring speed is 1000~1200 r / min.

6. The method for preparing the anti-caking agent according to claim 4, characterized in that, The stirring time for modification is 35-45 minutes.

7. The method for preparing the anti-caking agent according to claim 4, characterized in that, After the modification is completed, the material is discharged after being cooled to ≤35℃.

8. The application of the anti-caking agent according to any one of claims 1 to 3 as an anti-caking agent for phosphogypsum soil conditioner.

9. The application according to claim 8, characterized in that, The application includes the following steps: mixing the phosphogypsum soil conditioner with the anti-caking agent evenly.

10. The application according to claim 9, characterized in that, The amount of the anti-caking agent added to the phosphogypsum soil conditioner is x. When the moisture content of the phosphogypsum soil conditioner is <8%, 0.15wt%≤x<0.2wt%; when the moisture content of the phosphogypsum soil conditioner is 8~12%, 0.2wt%≤x<0.3wt%; when the moisture content of the phosphogypsum soil conditioner is >12%, 0.3wt%≤x≤0.35wt%.

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