Assistant for inhibiting strength reduction of fertilizer granules and preparation method thereof

Abstract

The invention belongs to an auxiliary agent for inhibiting strength reduction of fertilizer particles and a preparation method thereof. The auxiliary agent is at least prepared from the following raw materials: a water absorbent, a crystal control agent, a pH regulator, a dispersing agent and a pore filling agent, the water absorbent comprises an organic water absorbent and an inorganic water absorbent; the fertilizer can be matched with a compound fertilizer to improve the strength of fertilizer particles, the phenomenon that the strength is gradually reduced along with time is avoided, and meanwhile, the fertilizer can be quickly dissolved, the utilization rate of the fertilizer is improved, and the soil and the fertilizer efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer technology, and specifically relates to an adjuvant that inhibits the decline in fertilizer particle strength and its preparation method. Background Technology

[0002] With the development of modern agriculture towards large-scale and intelligent operations, mechanized fertilization has become a core means to improve production efficiency and reduce labor costs; and fertilizer intensity has become an important indicator of whether simultaneous sowing and fertilization, deep fertilization of rice, and aerial fertilization can be achieved; the decline in fertilizer intensity has many causes, such as:

[0003] (1) During fertilizer production (high tower granulation), the external moisture content of the fertilizer is low and the internal moisture content is high. That is, the moisture content inside and outside the fertilizer particles is unbalanced, which easily leads to moisture migration and causes the fertilizer strength to gradually decrease.

[0004] (2) During the storage of fertilizer, the humidity changes in the external environment cause the internal components of the fertilizer to repeatedly dissolve and crystallize, resulting in pores inside and causing the fertilizer strength to gradually decrease.

[0005] (3) During the storage of fertilizer, the temperature changes in the external environment cause repeated crystal changes in the internal crystals of the fertilizer, resulting in repeated expansion and contraction of the volume, which eventually leads to a gradual decrease in the strength of the fertilizer.

[0006] In traditional technologies, to address the problem of declining fertilizer strength, the common methods are reducing the moisture content of the finished fertilizer or adding inert fillers. Controlling fertilizer moisture content reduces water migration, fertilizer dissolution, and crystallization, thereby increasing fertilizer strength or delaying its decline during storage. Adding inert fillers increases fertilizer density, thus improving strength. Specifically, reducing moisture content is achieved through two methods: 1. Controlling the moisture content of raw materials within a reasonable range, but this requires high-quality raw materials, often resulting in high prices or shortages; 2. Controlling process conditions to increase granulation or drying temperatures, but this method is energy-intensive and puts significant pressure on subsequent cooling processes. Adding inert fillers primarily involves using raw materials such as attapulgite and magnesite. Fertilizers produced using these methods exhibit unstable performance and generally show a high initial strength followed by a gradual decline in strength during storage. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects in the prior art and provide an adjuvant for inhibiting the decline in fertilizer particle strength and its preparation method.

[0008] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0009] An adjuvant for inhibiting the decline in fertilizer particle strength, the adjuvant being made from at least the following raw materials: a water absorbent, a crystal control agent, a pH adjuster, a dispersant, and a pore filler; wherein the water absorbent includes organic water absorbents and inorganic water absorbents.

[0010] Preferably, the additive comprises the following raw materials in parts by weight: 25-55 parts of water absorbent, 10-15 parts of crystal control agent, 15-30 parts of pH adjuster, 0.5-15 parts of dispersant and 30-50 parts of pore filler; the weight ratio of organic water absorbent to inorganic water absorbent is 7-8:1-2.

[0011] Preferably, the inorganic absorbent is at least one of anhydrous magnesium sulfate, anhydrous calcium chloride, and magnesium sulfate monohydrate; the organic absorbent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer.

[0012] Preferably, the crystal control agent includes component A, component B, and component C;

[0013] Component A is at least one of polycarboxylic acid, polyethylene glycol, and polymaleic acid;

[0014] Component B is at least one of C8-C16 alkylbenzene sulfonate, C6-C9 alkyl sulfate, and C8-C10 alkyl sulfonate;

[0015] Component C is an alkyl dimethyl quaternary ammonium salt, wherein the alkyl group has 22-26 carbon atoms;

[0016] When the fertilizer does not contain nitrate nitrogen, the crystal control agent is a combination of component A and component B;

[0017] When the fertilizer contains nitrate nitrogen, the crystal control agent is a combination of components A and C.

[0018] Preferably, the weight ratio of component A to component B in the composition of component A and component B is 1-2:5-10;

[0019] The weight ratio of component A to component C in the composition of component A and component C is 1-2:1.5-2.

[0020] Preferably, the pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, wherein the molar ratio of monohydrogen phosphate to dihydrogen phosphate is 2-4:1-2;

[0021] The monohydrogen phosphate is at least one of sodium, potassium, calcium, ammonium, and magnesium salts, and the dihydrogen phosphate is at least one of sodium, potassium, calcium, ammonium, and magnesium salts.

[0022] Preferably, the dispersant is at least one of naphthalene sulfonate formaldehyde condensate, sodium methyl naphthalene sulfonate formaldehyde condensate, and sodium benzyl naphthalene sulfonate formaldehyde condensate.

[0023] Preferably, the pore filler is a composition of bentonite and solid sodium silicate, wherein the weight ratio of bentonite to solid sodium silicate is 6-8:1-2; wherein the modulus of solid sodium silicate is 1-3.

[0024] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0025] Step 1: Prepare organic water-absorbing agent; add 1-2 parts of biological polysaccharide and 50-100 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biological polysaccharide to completely dissolve;

[0026] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2-3 parts acrylic acid, 2-3 parts acrylamide and 0.02-0.05 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3-4 hours.

[0027] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 300-500 mesh to obtain an organic desiccant.

[0028] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0029] Preferably, the biopolysaccharide in step 1 is at least one of starch, seaweed polysaccharide, and lignin;

[0030] In step 4, the adjuvant that inhibits the decrease in fertilizer particle strength is pulverized to 300-500 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production and granulated using conventional high-tower granulation. The amount of adjuvant added is 2-10% of the fertilizer weight.

[0031] The present invention has the following advantages:

[0032] 1. The adjuvants in this invention contain inorganic and organic water-absorbing agents. The inorganic water-absorbing agent can quickly combine with free water to form a compound containing water of crystallization. It is characterized by fast water absorption but low water absorption capacity. The organic water-absorbing agent contains a large number of hydrophilic groups in its molecules, and is characterized by slow water absorption but large water absorption capacity. When the above-mentioned inorganic and organic water-absorbing agents are used as adjuvants in compound fertilizers, on the one hand, according to the characteristics of fertilizers produced by high-tower granulation (low external moisture and high internal moisture), the inorganic water-absorbing agent can quickly absorb the moisture of the fertilizer itself during the production process. The inorganic water-absorbing agent can quickly fix the moisture and inhibit the migration of moisture from the inside to the outside. At the same time, the organic water-absorbing agent can inhibit the migration of moisture from the outside to the inside caused by high environmental humidity during the long-term storage of fertilizers. The two work together to reduce the amount of free water inside and outside the fertilizer, or reduce water migration, reduce the occurrence of repeated dissolution and crystallization of crystals, and avoid the decrease in strength; furthermore, the organic absorbent in this invention is modified with biopolysaccharides, which can increase the polymer's degradability and reduce pollution to the environment and soil.

[0033] 2. The adjuvant in this invention contains a crystal control agent. This crystal control agent mainly inhibits the decrease in strength caused by changes in crystal form or solubility due to temperature variations by adsorbing specific sites on the crystal. Furthermore, the crystal control agent in this invention is adjusted differently depending on whether the fertilizer contains nitrate nitrogen. Specifically, when the fertilizer contains nitrate nitrogen, an important reason for the decrease in fertilizer strength is that the phase transition temperature of the two crystal structures of ammonium nitrate, monoclinic III (β) and orthorhombic IV (β), is approximately 32°C. When the ambient temperature repeatedly rises and falls around 32°C, the crystal structure changes repeatedly, and the crystal volume changes repeatedly, ultimately leading to a decrease in the strength of the fertilizer particles. Using the appropriate crystal control agent can raise its phase transition temperature to above 50°C, avoiding crystal form changes caused by ambient temperature variations. At the same time, the metal ions in the inorganic water absorbent can embed into the defects in the ammonium nitrate lattice, stabilizing the crystal structure. The combination of the two can effectively improve the situation of reduced strength of nitro fertilizer granules. When the fertilizer does not contain nitrate nitrogen, the main reasons for the decrease in fertilizer granule strength also include the repeated crystallization and dissolution of urea or ammonium salts in a small amount of free water when the temperature changes, which leads to the loosening of the internal dense structure and ultimately the decrease in granule strength. Based on this, the use of appropriate crystal control agents in free water can reduce the solubility of urea or ammonium ions, making it less likely to undergo the crystallization-dissolution process, and ultimately avoiding the decrease in strength.

[0034] 3. The adjuvants in this invention also contain a pH buffer, the main purpose of which is to maintain a relatively stable neutral pH environment in the fertilizer, avoiding significant changes in acidity or alkalinity caused by fluctuations in raw materials or processes during granulation. When the fertilizer is highly acidic, the carbonates in the raw materials react with acid to produce carbon dioxide, which escapes. When the fertilizer is highly alkaline, the ammonium ions in the fertilizer easily convert into ammonia gas, which escapes. The escape of this gas can easily cause the internal structure to collapse, resulting in a decrease in strength. Simultaneously, the fertilizer's hygroscopicity increases when it is too acidic or too alkaline, allowing external moisture to enter the granules. Using a pH buffer can keep the fertilizer in a stable neutral state, at which point the hygroscopic point is lower, and the carbonates and ammonium salts are in a stable equilibrium, preventing a decrease in strength.

[0035] 4. The pore filler described in this invention primarily functions to fill the internal gaps of the fertilizer, making it more compact. The bentonite pore filler contains a certain amount of silanol or aluminol hydroxyl groups, which can undergo a cross-linking and hardening reaction with sodium silicate to form a network structure, reducing free water and stabilizing strength. Simultaneously, some raw materials and organic water-absorbing agents contain hydroxyl groups; utilizing the trace amounts of moisture from the granulation process, sodium silicate can also react with these groups to further form a network structure and stabilize strength. Furthermore, the dispersant's role is to reduce surface tension and uniformly distribute the water-absorbing agent, crystal control agent, pH adjuster, pore filler, and other raw materials within the fertilizer.

[0036] 5. When the above-mentioned raw materials are combined, the present invention can synergistically inhibit the decline of fertilizer strength. In addition, it can also achieve rapid disintegration of fertilizer. When fertilizer is applied to the soil or dissolved in water for irrigation, the external moisture is far in excess relative to the fertilizer. At this time, the dispersant can reduce the surface tension and internal osmotic resistance of fertilizer particles, so that water can quickly wet the surface of fertilizer particles and enter the interior of fertilizer. At the same time, it combines with organic water absorbent and bentonite to quickly swell and promote the disintegration of particles, avoiding the problem of fertilizer with high strength and difficulty in dissolving.

[0037] 6. The dispersant described in this invention, in combination with components B and C of the crystal control agent, can reduce the osmotic resistance of nutrients in the soil and improve nutrient absorption. Furthermore, the long-chain structure of component A in the crystal control agent can bind with cationic nutrients such as ammonium ions, potassium ions, calcium and magnesium ions in the soil, preventing phosphate fertilizer fixation, thereby improving fertilizer utilization. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] This invention relates to an adjuvant for inhibiting the decline in fertilizer particle strength. The adjuvant is made from at least the following raw materials: water absorbent, crystal control agent, pH adjuster, dispersant, and pore filler; the water absorbent includes organic water absorbent and inorganic water absorbent.

[0040] Further, the additives are made from the following raw materials in parts by weight: 25-55 parts of water absorbent, 10-15 parts of crystal control agent, 15-30 parts of pH adjuster, 0.5-15 parts of dispersant and 30-50 parts of pore filler; the weight ratio of the organic water absorbent to the inorganic water absorbent is 7-8:1-2.

[0041] Furthermore, the inorganic water-absorbing agent is at least one of anhydrous magnesium sulfate, anhydrous calcium chloride, and magnesium sulfate monohydrate; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer.

[0042] Furthermore, the crystal control agent includes component A, component B, and component C;

[0043] Component A is at least one of polycarboxylic acid, polyethylene glycol, and polymaleic acid;

[0044] Component B is at least one of C8-C16 alkylbenzene sulfonate, C6-C9 alkyl sulfate, and C8-C10 alkyl sulfonate;

[0045] Component C is an alkyl dimethyl quaternary ammonium salt, wherein the alkyl group has 22-26 carbon atoms;

[0046] When the fertilizer does not contain nitrate nitrogen, the crystal control agent is a combination of component A and component B;

[0047] When the fertilizer contains nitrate nitrogen, the crystal control agent is a combination of components A and C.

[0048] Furthermore, in the composition of component A and component B, the weight ratio of component A to component B is 1-2:5-10;

[0049] The weight ratio of component A to component C in the composition of component A and component C is 1-2:1.5-2.

[0050] Furthermore, the pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 2-4:1-2;

[0051] The monohydrogen phosphate is at least one of sodium, potassium, calcium, ammonium, and magnesium salts, and the dihydrogen phosphate is at least one of sodium, potassium, calcium, ammonium, and magnesium salts.

[0052] Further, the dispersant is at least one of naphthalene sulfonate formaldehyde condensate, sodium methyl naphthalene sulfonate formaldehyde condensate, and sodium benzyl naphthalene sulfonate formaldehyde condensate.

[0053] Furthermore, the pore filler is a composition of bentonite and solid sodium silicate, wherein the weight ratio of bentonite to solid sodium silicate is 6-8:1-2; wherein the modulus of solid sodium silicate is 1-3.

[0054] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0055] Step 1: Prepare organic water-absorbing agent; add 1-2 parts of biological polysaccharide and 50-100 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biological polysaccharide to completely dissolve;

[0056] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2-3 parts of acrylic acid, 2-3 parts of acrylamide and 0.02-0.05 parts of ammonium persulfate to the reactor to carry out the reaction for 3-4 hours.

[0057] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 300-500 mesh to obtain an organic desiccant.

[0058] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0059] Furthermore, the biopolysaccharide in step 1 is at least one of starch, seaweed polysaccharide, and lignin;

[0060] In step 4, the adjuvant that inhibits the decrease in fertilizer particle strength is pulverized to 300-500 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production and granulated using conventional high-tower granulation. The amount of adjuvant added is 2-10% of the fertilizer weight.

[0061] This invention is primarily designed for high-tower compound fertilizers. During use, the additives are added to the compound fertilizer slurry, mixed uniformly, and then granulated. The compound fertilizer granules with the additives of this invention ensure an initial strength (after production) of no less than 45N, and that during long-term storage (within 180 days), there will be no significant decrease in strength over time (a significant decrease in strength, as described here, refers to a strength greater than 3N at any point between the production strength and any point within 180 days; that is, the fertilizer produced using this invention, under normal storage conditions, will maintain its strength from production to within 180 days). At any given time, the fertilizer strength is no less than 3N or more of the strength at the time of production. Furthermore, this invention also prevents the fertilizer from becoming difficult to dissolve due to high strength, and it improves fertilizer utilization, soil quality, and fertilizer efficiency. As is well known, fertilizer strength is affected by many factors, such as the moisture content of the fertilizer during production, the influence of humidity and temperature during storage, and internal collapse caused by the release of carbon dioxide or ammonia from the fertilizer itself. This invention achieves its characteristic of improving fertilizer strength through the synergistic effect of water-absorbing agents, crystal-controlling agents, pH adjusters, dispersants, and pore-filling agents in the adjuvants. Specifically… The invention utilizes a water-absorbing agent to control moisture levels during production and storage, and a crystal-controlling agent to suppress changes in crystal form or solubility caused by temperature variations. Furthermore, the dispersant of this invention not only facilitates rapid dispersion and mixing of fertilizer slurry and additives during fertilizer production, but also enables rapid wetting of fertilizer granules and penetration into the fertilizer interior during application. It combines with organic water-absorbing agents and bentonite to cause fertilizer swelling, resulting in rapid granule disintegration. Moreover, the combination of the dispersant's characteristics with the crystal-controlling agent reduces nutrient permeability resistance in the soil and improves nutrient absorption. Furthermore, it can combine with ammonium ions, potassium ions, calcium and magnesium ions and other cationic nutrients in the soil to prevent phosphate fertilizer fixation, thereby improving fertilizer utilization. The organic water absorbent and bentonite itself contain water-absorbing groups and porous structures that can loosen the soil and improve its water and fertilizer retention capacity. At the same time, the pH buffer can improve the acid-base imbalance of the crop rhizosphere soil and provide a suitable neutral environment for the crop. In addition, the inorganic water absorbent and void filler contained in this invention contain trace elements, and sodium silicate contains silicon. The above substances work together with the nutrients in the fertilizer to improve fertilizer efficiency.

[0062] To explain the present invention in more detail, the invention will now be further described with reference to embodiments. Specific embodiments are as follows:

[0063] Example 1

[0064] An adjuvant for inhibiting the decline in fertilizer granule strength, the adjuvant comprising the following raw materials in parts by weight: 56 parts water absorbent, 16 parts crystal control agent, 14 parts pH adjuster, 16 parts dispersant, and 25 parts pore filler; wherein the weight ratio of the organic water absorbent to the inorganic water absorbent is 7:3.

[0065] The inorganic water-absorbing agent is anhydrous magnesium sulfate; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer. The crystal control agent comprises component A and component B; component A is polymaleic acid; component B is a C8-C10 alkyl sulfonate; the weight ratio of component A to component B in the composition is 1:10; the pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 2:2; the monohydrogen phosphate is sodium monohydrogen phosphate, and the dihydrogen phosphate is magnesium dihydrogen phosphate. The dispersant is a sodium benzyl naphthalene sulfonate formaldehyde condensate. The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 6:2; wherein the modulus of the solid sodium silicate is 1.

[0066] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0067] Step 1: Prepare organic desiccant; add 1 part of biopolysaccharide and 50 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biopolysaccharide to completely dissolve;

[0068] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2 parts acrylic acid, 3 parts acrylamide and 0.03 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3 hours.

[0069] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 300 mesh to obtain an organic desiccant.

[0070] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0071] Furthermore, the biopolysaccharide in step 1 is starch;

[0072] In step 4, the adjuvant used to inhibit the decrease in fertilizer particle strength is pulverized to 300 mesh before use. The pulverized adjuvant is then added to the raw materials used in fertilizer production, and granulation is performed using a conventional high-tower granulation method. The amount of adjuvant added is 2% of the fertilizer weight. For the compound fertilizer without nitrate nitrogen prepared in this embodiment, the average initial strength of the compound fertilizer particles is 45.2 N. Samples of the retained fertilizer were tested 180 days after fertilizer production, and their average strength was 45 N.

[0073] Example 2

[0074] An adjuvant for inhibiting the decline in fertilizer granule strength, the adjuvant comprising the following raw materials in parts by weight: 25 parts water absorbent, 10 parts crystal control agent, 15 parts pH adjuster, 0.5 parts dispersant, and 30 parts pore filler; wherein the weight ratio of the organic water absorbent to the inorganic water absorbent is 7:1.

[0075] The inorganic water-absorbing agent is anhydrous calcium chloride; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer. The crystal control agent includes component A and component C; component A is polycarboxylic acid; component C is an alkyl dimethyl quaternary ammonium salt, wherein the alkyl group has 22-26 carbon atoms; the weight ratio of component A to component C in the composition of component A and component C is 1:1.5. The pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 2:1; the monohydrogen phosphate is a mixture of potassium monohydrogen phosphate, calcium monohydrogen phosphate, and ammonium monohydrogen phosphate, and the dihydrogen phosphate is a mixture of sodium dihydrogen phosphate, potassium dihydrogen phosphate, calcium dihydrogen phosphate, and ammonium dihydrogen phosphate; the dispersant is a naphthalene sulfonate formaldehyde condensate. The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 8:1; wherein the modulus of solid sodium silicate is 3.

[0076] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0077] Step 1: Prepare organic desiccant; add 2 parts of biopolysaccharide and 50 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biopolysaccharide to completely dissolve;

[0078] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2 parts acrylic acid, 2 parts acrylamide and 0.03 parts ammonium persulfate to the reactor for reaction, and the reaction time is 4 hours.

[0079] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 500 mesh to obtain an organic desiccant.

[0080] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0081] Furthermore, the biopolysaccharide in step 1 is a seaweed polysaccharide;

[0082] In step 4, the adjuvant used to inhibit the decline in fertilizer particle strength is pulverized to 500 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production, and granulation is performed using a conventional high-tower granulation method. The amount of adjuvant added is 10% of the fertilizer weight. For the compound fertilizer containing nitrate nitrogen prepared in this embodiment, the average initial strength of the compound fertilizer particles is 48.8 N. On the 180th day after fertilizer production, samples of the retained fertilizer were tested, and their average strength was 49.3 N.

[0083] Example 3

[0084] An adjuvant for inhibiting the decline in fertilizer granule strength, the adjuvant comprising the following raw materials in parts by weight: 55 parts water absorbent, 15 parts crystal control agent, 30 parts pH adjuster, 15 parts dispersant, and 50 parts pore filler; wherein the weight ratio of the organic water absorbent to the inorganic water absorbent is 8:2.

[0085] The inorganic water-absorbing agent is a mixture of anhydrous calcium chloride and magnesium sulfate monohydrate; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer. The crystal control agent comprises component A and component C; component A is polyethylene glycol; component C is an alkyl dimethyl quaternary ammonium salt, wherein the alkyl group has 22-26 carbon atoms; the weight ratio of component A to component C in the composition is 2:1.8. The pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 4:1.5; the monohydrogen phosphate is magnesium monohydrogen phosphate, and the dihydrogen phosphate is ammonium dihydrogen phosphate. The dispersant is a mixture of naphthalene sulfonate formaldehyde condensate and sodium methylnaphthalene sulfonate formaldehyde condensate. The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 7:1.5; wherein the modulus of solid sodium silicate is 2.

[0086] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0087] Step 1: Prepare organic desiccant; add 1.5 parts of biopolysaccharide and 90 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biopolysaccharide to dissolve completely;

[0088] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2.5 parts acrylic acid, 2.5 parts acrylamide and 0.02 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3.5 hours.

[0089] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 400 mesh to obtain an organic desiccant.

[0090] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0091] Furthermore, the biopolysaccharide in step 1 is lignin;

[0092] In step 4, the adjuvant used to inhibit the decline in fertilizer particle strength is pulverized to 400 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production, and granulation is performed using a conventional high-tower granulation method. The amount of adjuvant added is 7% of the fertilizer weight. For the compound fertilizer containing nitrate nitrogen prepared in this embodiment, the average initial strength of the compound fertilizer particles is 52.6 N. On the 180th day after fertilizer production, samples of the retained fertilizer were tested, and their average strength was 53.8 N.

[0093] Example 4

[0094] An adjuvant for inhibiting the decline in fertilizer particle strength, the adjuvant comprising the following raw materials in parts by weight: 40 parts water absorbent, 12 parts crystal control agent, 23 parts pH adjuster, 8 parts dispersant, and 40 parts pore filler; wherein the weight ratio of the organic water absorbent to the inorganic water absorbent is 7:1.

[0095] The inorganic water-absorbing agent is magnesium sulfate monohydrate; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer. The crystal control agent comprises component A and component C; component A is a mixture of polycarboxylic acid and polyethylene glycol; component C is an alkyl dimethyl quaternary ammonium salt, wherein the alkyl group has 22-26 carbon atoms; the weight ratio of component A to component C in the composition is 1.5:2. The pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 3:1.5; the monohydrogen phosphate is ammonium monohydrogen phosphate, and the dihydrogen phosphate is potassium dihydrogen phosphate. The dispersant is sodium methylnaphthalenesulfonate formaldehyde condensate. The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 6:1; wherein the modulus of solid sodium silicate is 2.

[0096] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0097] Step 1: Prepare organic desiccant; add 2 parts of biopolysaccharide and 50 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biopolysaccharide to completely dissolve;

[0098] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 3 parts acrylic acid, 2 parts acrylamide and 0.04 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3 hours.

[0099] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 300 mesh to obtain an organic desiccant.

[0100] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0101] Furthermore, the biopolysaccharide in step 1 is a mixture of starch and seaweed polysaccharide;

[0102] In step 4, the adjuvant used to inhibit the decline in fertilizer particle strength is pulverized to 300 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production, and granulation is performed using a conventional high-tower granulation method. The amount of adjuvant added is 6% of the fertilizer weight. For the compound fertilizer containing nitrate nitrogen prepared in this embodiment, the average initial strength of the compound fertilizer particles is 50.3 N. On the 180th day after fertilizer production, samples of the retained fertilizer were tested, and their average strength was 51.5 N.

[0103] Example 5

[0104] An adjuvant for inhibiting the decline in fertilizer particle strength, the adjuvant comprising the following raw materials in parts by weight: 30 parts water absorbent, 13 parts crystal control agent, 30 parts pH adjuster, 1 part dispersant and 35 parts pore filler; wherein the weight ratio of the organic water absorbent to the inorganic water absorbent is 7.3:1.6.

[0105] The inorganic water-absorbing agent is anhydrous magnesium sulfate and anhydrous calcium chloride; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer. The crystal control agent comprises component A and component B; component A is a mixture of polyethylene glycol and polymaleic acid; component B is a mixture of C8-C16 alkylbenzene sulfonate and C6-C9 alkyl sulfate; the weight ratio of component A to component B in the composition is 2:5; the pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 3:2; the monohydrogen phosphate is potassium monohydrogen phosphate, and the dihydrogen phosphate is ammonium dihydrogen phosphate; the dispersant is naphthalenesulfonate formaldehyde condensate. The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 7:2; wherein the modulus of solid sodium silicate is 3.

[0106] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0107] Step 1: Prepare organic desiccant; add 2 parts of biopolysaccharide and 60 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biopolysaccharide to completely dissolve;

[0108] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 3 parts acrylic acid, 3 parts acrylamide and 0.03 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3.5h.

[0109] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 400 mesh to obtain an organic desiccant.

[0110] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0111] Furthermore, the biopolysaccharide in step 1 is starch;

[0112] In step 4, the adjuvant used to inhibit the decline in fertilizer particle strength is pulverized to 400 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production, and granulation is performed using a conventional high-tower granulation method. The amount of adjuvant added is 9% of the fertilizer weight. For the nitrate-free compound fertilizer prepared in this embodiment, the average initial strength of the compound fertilizer particles is 57.3 N. On the 180th day after fertilizer production, samples of the retained fertilizer were tested, and their average strength was 57.5 N.

[0113] Example 6

[0114] An adjuvant for inhibiting the decline in fertilizer granule strength, the adjuvant comprising the following raw materials in parts by weight: 45 parts water absorbent, 11 parts crystal control agent, 28 parts pH adjuster, 12 parts dispersant and 36 parts pore filler; wherein the weight ratio of the organic water absorbent to the inorganic water absorbent is 7:1.7.

[0115] The inorganic water-absorbing agent is a mixture of anhydrous magnesium sulfate, anhydrous calcium chloride, and magnesium sulfate monohydrate; the organic water-absorbing agent is a biopolysaccharide-polyacrylic acid-polyacrylamide copolymer. The crystal control agent comprises component A and component B; component A is polycarboxylic acid; component B is C8-C16 alkylbenzene sulfonate; the weight ratio of component A to component B in the composition is 1.5:8; the pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 2:1.7; the monohydrogen phosphate is a mixture of sodium monohydrogen phosphate and calcium monohydrogen phosphate, and the dihydrogen phosphate is potassium dihydrogen phosphate. The dispersant is a mixture of naphthalene sulfonate formaldehyde condensate, sodium methylnaphthalene sulfonate formaldehyde condensate, and sodium benzyl naphthalene sulfonate formaldehyde condensate. The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 8:1; wherein the modulus of solid sodium silicate is 2.

[0116] This invention also provides a method for preparing an adjuvant that inhibits the decline in fertilizer granule strength, the method comprising the following steps:

[0117] Step 1: Prepare organic desiccant; add 2 parts of biopolysaccharide and 70 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biopolysaccharide to completely dissolve;

[0118] Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2.5 parts acrylic acid, 2.5 parts acrylamide and 0.05 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3 hours.

[0119] Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 500 mesh to obtain an organic desiccant.

[0120] Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

[0121] Furthermore, the biopolysaccharide in step 1 is a seaweed polysaccharide;

[0122] In step 4, the adjuvant used to inhibit the decline in fertilizer particle strength is pulverized to 500 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production, and granulation is performed using a conventional high-tower granulation method. The amount of adjuvant added is 3% of the fertilizer weight. For the nitrate-free compound fertilizer prepared in this embodiment, the average initial strength of the compound fertilizer particles is 55.2 N. On the 180th day after fertilizer production, samples of the retained fertilizer were tested, and their average strength was 55.9 N.

[0123] It should be noted that the C8-C16 alkylbenzene sulfonates, C6-C9 alkyl sulfates, and C8-C10 alkyl sulfonates mentioned in the previous embodiments can be specifically potassium salts or sodium salts; the alkyl dimethyl quaternary ammonium salts can be specifically potassium salts or sodium salts; and the naphthalene sulfonate formaldehyde condensate, methyl naphthalene sulfonate sodium formaldehyde condensate, and benzyl naphthalene sulfonate sodium formaldehyde condensate can be specifically potassium salts, sodium salts, or calcium salts.

[0124] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0125] Test case

[0126] The performance of fertilizers with the adjuvants of this invention will now be tested; specifically, the role of the adjuvants in this invention will be further described through single-factor experiments; at the same time, the relevant performance will be verified by applying the corresponding fertilizers to corn fields and using the same field management.

[0127] Comparative Example 1:

[0128] The formula is based on urea-chloride 34-5-5, with the specific proportions being 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, and 3% limestone powder. Granulation is carried out according to conventional process parameters. No additives as described in this invention are added in Comparative Example 1.

[0129] Comparative Example 2

[0130] The formula is based on Gaota urea chloride 34-5-5, with the specific proportions being 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, 3.6% limestone powder, and 2.4% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 5 parts water absorbent, 15 parts crystal control agent, 20 parts pH adjuster, 10 parts dispersant, and 30 parts pore filler. All water absorbents are organic water absorbents, which are seaweed polysaccharide-polyacrylic acid-polyacrylamide copolymers (randomly selected from the organic water absorbents prepared in Example 3 above). The crystal control agent is a combination of polycarboxylic acid and sodium 16-alkylbenzenesulfonate in a weight ratio of 1:1. The pH adjuster is a combination of dicalcium hydrogen phosphate and calcium dihydrogen phosphate in a weight ratio of 1:1; the dispersant is sodium naphthalene sulfonate formaldehyde condensate; and the pore filler is a combination of bentonite and solid sodium silicate in a weight ratio of 6:1, wherein the solid sodium silicate has a modulus of 3. The additives in Comparative Example 2 do not contain inorganic water-absorbing agents.

[0131] Comparative Example 3

[0132] The formula is based on Gaota urea chloride-based 34-5-5, with the specific proportions as follows: 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, 3.15% limestone powder, and 2.85% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 20 parts water absorbent, 15 parts crystal control agent, 20 parts pH adjuster, 10 parts dispersant, and 30 parts pore filler. The water absorbent is entirely inorganic, specifically anhydrous magnesium sulfate. The crystal control agent is a combination of polycarboxylic acid and sodium 16-alkylbenzene sulfonate in a weight ratio of 1:1. The pH adjuster is a combination of dicalcium hydrogen phosphate and calcium dihydrogen phosphate in a weight ratio of 2:2. The dispersant is sodium naphthalene sulfonate formaldehyde condensate. The pore filler is a combination of bentonite and solid sodium silicate in a weight ratio of 6:1, with the solid sodium silicate having a modulus of 3. The additives in Comparative Example 3 do not contain organic water-absorbing agents;

[0133] Comparative Example 4

[0134] The formula is based on Gaota urea chloride 34-5-5, with the specific proportions as follows: 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, 3.45% limestone powder, and 2.55% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 25 parts water absorbent, 20 parts pH adjuster, 10 parts dispersant, and 30 parts pore filler. The water absorbent is a combination of inorganic and organic water absorbents in a weight ratio of 4:1. The inorganic water absorbent is anhydrous magnesium sulfate, and the organic water absorbent is a seaweed polysaccharide-polyacrylic acid-polyacrylamide copolymer (randomly selected from the organic water absorbent prepared in Example 3 above). The pH adjuster is a combination of dicalcium hydrogen phosphate and calcium dihydrogen phosphate in a weight ratio of 1:1; the dispersant is sodium naphthalene sulfonate formaldehyde condensate; and the pore filler is a combination of bentonite and solid sodium silicate in a weight ratio of 6:1, wherein the solid sodium silicate has a modulus of 3. The additives in Comparative Example 4 do not contain crystal-controlling agents.

[0135] Comparative Example 5

[0136] The formula is based on Gaota urea chloride 34-5-5, with the specific proportions as follows: 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, 3.6% limestone powder, and 2.4% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 25 parts water absorbent, 15 parts crystal control agent, 10 parts dispersant, and 30 parts pore filler. The water absorbent is a combination of inorganic and organic water absorbents in a weight ratio of 4:1. The inorganic water-absorbing agent is anhydrous magnesium sulfate; the organic water-absorbing agent is a seaweed polysaccharide-polyacrylic acid-polyacrylamide copolymer (randomly selected from the organic water-absorbing agent prepared in Example 3 above); the crystal control agent is a combination of polycarboxylic acid and sodium 16-alkylbenzene sulfonate in a weight ratio of 1:1; the dispersant is sodium naphthalene sulfonate formaldehyde condensate; and the pore filler is a combination of bentonite and solid sodium silicate in a weight ratio of 6:1, wherein the solid sodium silicate has a modulus of 3. The additives in Comparative Example 5 do not contain a pH adjuster.

[0137] Comparative Example 6

[0138] Based on the high-tower urea chloride-based 34-5-5 formula, the specific ratio is 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, 3.9% limestone powder, and 2.1% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 25 parts water absorbent, 15 parts crystal control agent, 20 parts pH adjuster, and 10 parts dispersant. The water absorbent is a combination of inorganic and organic water absorbents in a weight ratio of 4:1. The inorganic water absorbent is anhydrous magnesium sulfate, the organic water absorbent is a seaweed polysaccharide-polyacrylic acid-polyacrylamide copolymer (randomly selected from the organic water absorbent prepared in Example 3 above), the crystal control agent is a combination of polycarboxylic acid and sodium 16-alkylbenzene sulfonate in a weight ratio of 1:1, the pH adjuster is a combination of dicalcium hydrogen phosphate and calcium dihydrogen phosphate in a weight ratio of 1:1, and the dispersant is sodium naphthalene sulfonate formaldehyde condensate. The additives in Comparative Example 6 do not contain pore fillers.

[0139] Comparative Example 7

[0140] The formula is based on Gaota urea chloride 34-5-5, with the specific proportions being 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, 3.3% limestone powder, and 2.7% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 25 parts water absorbent, 15 parts crystal control agent, 20 parts pH adjuster, and 30 parts pore filler. The water absorbent is a combination of inorganic and organic water absorbents in a weight ratio of 4:1. The inorganic water absorbent is anhydrous magnesium sulfate, the organic water absorbent is a seaweed polysaccharide-polyacrylic acid-polyacrylamide copolymer (randomly selected from the organic water absorbent prepared in Example 3 above), and the crystal control agent is a combination of polycarboxylic acid and sodium 16-alkylbenzenesulfonate in a weight ratio of 1:1. The pH adjuster is a combination of dicalcium hydrogen phosphate and calcium dihydrogen phosphate in a weight ratio of 1:1. The pore filler is a combination of bentonite and solid sodium silicate in a weight ratio of 6:1. The solid sodium silicate has a modulus of 3. The additives in Comparative Example 7 do not contain dispersants.

[0141] Comparative Example 8

[0142] The formula is based on Gaota urea chloride 34-5-5, with the specific proportions being 50% urea, 11.4% 55% agricultural monoammonium phosphate, 10% potassium chloride, 35.6% dry ammonium phosphate, and 3% additives. Granulation is carried out according to conventional process parameters. The additives consist of the following components: 25 parts water absorbent, 15 parts crystal control agent, 20 parts pH adjuster, 10 parts dispersant, and 30 parts pore filler. The water absorbent is a combination of inorganic and organic water absorbents in a weight ratio of 4:1. The inorganic water absorbent is anhydrous magnesium sulfate, the organic water absorbent is a seaweed polysaccharide-polyacrylic acid-polyacrylamide copolymer (randomly selected from the organic water absorbent prepared in Example 3 above), and the crystal control agent is a combination of polycarboxylic acid and sodium 16-alkylbenzenesulfonate in a weight ratio of 1:1. The pH adjuster is a combination of dicalcium hydrogen phosphate and calcium dihydrogen phosphate in a weight ratio of 1:1. The dispersant is sodium naphthalene sulfonate formaldehyde condensate. The pore filler is a combination of bentonite and solid sodium silicate in a weight ratio of 6:1. The modulus of the solid sodium silicate is 3.

[0143] The specific results are as follows:

[0144]

[0145] As seen in Comparative Example 1, the initial strength after 1 day of treatment was 29 N, which was relatively low. As time went on, the strength showed a significant downward trend. The main reason was that the formula contained a lot of urea, resulting in large internal voids at the beginning of granulation. Later, as the internal and external moisture continued to exchange, the stone powder and free acid produced carbon dioxide, causing structural collapse and ultimately low strength.

[0146] Comparing Comparative Example 2 with Comparative Example 1, Comparative Example 2 shows a significant increase in initial strength to 40N after one day, but the strength gradually decreases over time. This is mainly because, in addition to the inorganic water-absorbing agent, all other adjuvants were added, which to some extent reduced free water, lowered porosity, and inhibited water exchange during storage, resulting in a significant increase compared to Comparative Example 2 at different time points. However, due to the lack of a strong water-absorbing effect from the inorganic water-absorbing agent, the fertilizer still contains a relatively high amount of free water, leading to a decrease in strength. The disintegration time is significantly better than Comparative Example 1 because of the surface-active effect of the crystal-controlling agent and dispersant, which, after dissolving in water, helps water quickly penetrate the fertilizer interior and promotes rapid swelling of the organic water-absorbing agent and pore-filling agent. In terms of yield, nutrient utilization rate, and soil bulk density, it is significantly better than Comparative Example 1. This is mainly because the various adjuvants work synergistically, playing a positive role in improving the supply of micronutrients, improving soil, and promoting nutrient transfer to the roots and absorption.

[0147] Comparing Comparative Example 3 with Comparative Example 1, it can be observed that the initial strength reached 48 N after 1 day, but the strength gradually decreased over time. The main reason is that, in addition to the superabsorbent polymer, all other adjuvants were added, which to some extent reduced porosity and inhibited water exchange during storage. Compared to Comparative Example 1, the strength increased significantly at different time points. However, due to the absence of an organic superabsorbent polymer, the ingress of external moisture was not inhibited in the later stages of storage, leading to a decrease in strength. Comparing Comparative Example 3 with Comparative Example 2, it can be observed that the strength after 1 day with the inorganic superabsorbent polymer was significantly higher than that with the organic superabsorbent polymer. This is because the inorganic superabsorbent polymer can quickly fix water, resulting in a rapid increase in strength in a short period. The disintegration time was significantly weaker than Comparative Example 1 because, without the organic superabsorbent polymer, the increased strength did not easily lead to swelling and disintegration. In terms of yield, nutrient utilization rate, and soil bulk density, it was significantly better than the comparative example. The main reason is that the various adjuvants worked synergistically, playing a positive role in improving the supply of micronutrients, improving the soil, and promoting nutrient transfer to the roots and absorption.

[0148] Comparing Comparative Example 4 and Comparative Example 1, it can be observed that the initial strength reached 46 N after 1 day, but the strength gradually decreased over time. The main reason is that all adjuvants except the crystal control agent were added, which reduced free water and porosity to some extent, and inhibited water exchange during storage. However, due to the absence of the crystal control agent, the solubility of urea or ammonium salts in the remaining free water could not be reduced, resulting in repeated dissolution and crystallization, ultimately leading to a decrease in strength. However, compared to Comparative Example 1, the strength was significantly increased at different time points. The disintegration time was significantly better than Comparative Example 1 because the dispersant has surface-active properties, which, after dissolving in water, helps water quickly penetrate the fertilizer, promoting the rapid swelling of the organic water-absorbing agent and pore-filling agent. In terms of yield, nutrient utilization rate, and soil bulk density, it was significantly better than the comparative example. The main reason is that the various adjuvants worked synergistically, playing a positive role in improving the supply of micronutrients, improving the soil, and promoting nutrient transfer to the roots and absorption.

[0149] Comparing Comparative Example 5 and Comparative Example 1, it can be observed that the initial strength reached 45N after 1 day, but the strength gradually decreased over time. The main reason is that all adjuvants except the pH adjuster were added, which to some extent reduced free water, lowered porosity, and inhibited water exchange during storage. However, due to the absence of a pH adjuster, a stable pH environment could not be maintained, leading to the reaction of free acid with limestone powder, resulting in the release of carbon dioxide and ultimately a decrease in strength. However, compared to Comparative Example 1, the strength was significantly increased at different time points. The disintegration time was significantly better than Comparative Example 1 because the dispersant has surface-active properties, which, after dissolving in water, helps water quickly penetrate the fertilizer, promoting the rapid swelling of the organic water-absorbing agent and pore-filling agent. In terms of yield, nutrient utilization rate, and soil bulk density, it was significantly better than the comparative example. This is mainly because the various adjuvants worked synergistically, playing a positive role in improving the supply of micronutrients, improving soil, and promoting nutrient transfer to the roots and absorption.

[0150] Comparing Comparative Example 6 and Comparative Example 1, it can be observed that the initial strength reached 36 N after 1 day, and the strength decreased over time. The main reason is that, in addition to the pore filler, all other additives were added, which to some extent reduced free water, lowered the solubility of urea or ammonium ions, and inhibited water exchange during storage. However, due to the absence of the pore filler, the pores during granulation could not be fully filled, ultimately leading to a decrease in strength. However, compared to Comparative Example 1, the strength increased significantly at different time points. The disintegration time was similar to that of Comparative Example 1. In terms of yield, nutrient utilization rate, and soil bulk density, it was significantly better than the comparative example. The main reason is that the various additives worked synergistically, playing a positive role in improving the supply of micronutrients, improving the soil, and promoting nutrient transfer to the roots and absorption.

[0151] Comparing Comparative Example 7 with the Comparative Example, it can be observed that the initial strength reached 39 N after 1 day, but the strength gradually decreased over time. The main reason is that, except for the dispersant, all other adjuvants were added, which to some extent reduced free water, decreased porosity, reduced the solubility of urea or ammonium ions, and inhibited water exchange during storage. However, due to the absence of a dispersant, the other adjuvants could not disperse well in the fertilizer and could not fully exert their effects, ultimately leading to a decrease in strength. However, compared to Comparative Example 1, the strength was significantly increased at different time points. The disintegration time was significantly better than Comparative Example 1 because the dispersant has surface-active properties, which, after dissolving in water, helps water to quickly penetrate the fertilizer interior and promotes the rapid swelling of the organic water-absorbing agent and pore-filling agent. In terms of yield, nutrient utilization rate, and soil bulk density, it was significantly better than the Comparative Example. The main reason is that the various adjuvants worked synergistically, playing a positive role in improving the supply of micronutrients, improving the soil, and promoting nutrient transfer to the roots and absorption.

[0152] Comparing Comparative Example 8 with Comparative Examples 1-7, it can be observed that the initial strength reached 50 N after 1 day, and the strength did not decrease with time, but rather increased slightly. This is mainly due to the combined effects of various adjuvants. During storage, organic and inorganic water absorbents reduced free water, crystal control agents reduced the solubility of urea and ammonium salts, pH adjusters maintained the fertilizer's acid-base range in a neutral state to prevent carbon dioxide escape, pore fillers reduced porosity and facilitated cross-linking reactions with other components, and dispersants helped to ensure uniform distribution of the materials. With prolonged storage, the synergistic effects of these adjuvants continued to contribute, resulting in a slight increase in final strength. The adjuvants also showed the best performance in terms of disintegration time, yield, nutrient uptake, and soil bulk density. This is primarily because the components of the adjuvants worked synergistically, maintaining stable final strength and providing beneficial effects, with significant contributions to promoting disintegration, increasing yield, improving fertilizer utilization, and enhancing soil quality.

[0153] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An adjuvant for inhibiting the decline in fertilizer granule strength, characterized in that: The additive is made from at least the following raw materials: water absorbent, crystal control agent, pH adjuster, dispersant, and pore filler; the water absorbent includes organic water absorbent and inorganic water absorbent.

2. The adjuvant for inhibiting the decline in fertilizer particle strength according to claim 1, characterized in that: The additives are made from the following raw materials in parts by weight: 25-55 parts of water absorbent, 10-15 parts of crystal control agent, 15-30 parts of pH adjuster, 0.5-15 parts of dispersant and 30-50 parts of pore filler; the weight ratio of organic water absorbent to inorganic water absorbent is 7-8:1-2.

3. An adjuvant for inhibiting the decline in fertilizer particle strength according to claim 1 or 2, characterized in that: The inorganic desiccant is at least one of anhydrous magnesium sulfate, anhydrous calcium chloride, and magnesium sulfate monohydrate. The organic water absorbent is a copolymer of biopolysaccharide, polyacrylic acid, and polyacrylamide.

4. An adjuvant for inhibiting the decline in fertilizer particle strength according to claim 1 or 2, characterized in that: The crystal control agent includes component A, component B, and component C; Component A is at least one of polycarboxylic acid, polyethylene glycol, and polymaleic acid; Component B is at least one of C8-C16 alkylbenzene sulfonate, C6-C9 alkyl sulfate, and C8-C10 alkyl sulfonate; Component C is an alkyl dimethyl quaternary ammonium salt, wherein the alkyl group has 22-26 carbon atoms; When the fertilizer does not contain nitrate nitrogen, the crystal control agent is a combination of component A and component B; When the fertilizer contains nitrate nitrogen, the crystal control agent is a combination of components A and C.

5. The adjuvant for inhibiting the decline in fertilizer particle strength according to claim 4, characterized in that: The weight ratio of component A to component B in the composition of component A and component B is 1-2:5-10; The weight ratio of component A to component C in the composition of component A and component C is 1-2:1.5-2.

6. An adjuvant for inhibiting the decline in fertilizer particle strength according to claim 1 or 2, characterized in that: The pH adjuster is a combination of monohydrogen phosphate and dihydrogen phosphate, with a molar ratio of monohydrogen phosphate to dihydrogen phosphate of 2-4:1-2. The monohydrogen phosphate is at least one of sodium, potassium, calcium, ammonium, and magnesium salts, and the dihydrogen phosphate is at least one of sodium, potassium, calcium, ammonium, and magnesium salts.

7. An adjuvant for inhibiting the decline in fertilizer particle strength according to claim 1 or 2, characterized in that: The dispersant is at least one of naphthalene sulfonate formaldehyde condensate, sodium methyl naphthalene sulfonate formaldehyde condensate, and sodium benzyl naphthalene sulfonate formaldehyde condensate.

8. An adjuvant for inhibiting the decline in fertilizer particle strength according to claim 1 or 2, characterized in that: The pore filler is a composition of bentonite and solid sodium silicate, with a weight ratio of bentonite to solid sodium silicate of 6-8:1-2; wherein the modulus of solid sodium silicate is 1-3.

9. A method for preparing an adjuvant to inhibit the decline in fertilizer granule strength, characterized in that: The preparation method includes the following steps: Step 1: Prepare organic water-absorbing agent; add 1-2 parts of biological polysaccharide and 50-100 parts of distilled water to the reaction vessel, raise the temperature of the material inside the reaction vessel to 90°C, and keep it for 1 hour to allow the biological polysaccharide to completely dissolve; Step 2: Cool the completely dissolved system from Step 1 to 60°C and introduce nitrogen gas into the reactor; under the above temperature and nitrogen atmosphere, add 2-3 parts acrylic acid, 2-3 parts acrylamide and 0.02-0.05 parts ammonium persulfate to the reactor for reaction, and the reaction time is 3-4 hours. Step 3: After the reaction in Step 2 is completed, the material inside the reactor is cooled to room temperature, and the product is dried and pulverized to 300-500 mesh to obtain an organic desiccant. Step 4: Mix the organic water absorbent described in Step 1 with the inorganic water absorbent, crystal control agent, pH adjuster, dispersant and pore filler to obtain the adjuvant that inhibits the decrease in fertilizer particle strength.

10. The method for preparing an adjuvant for inhibiting the decline in fertilizer granule strength according to claim 9, characterized in that: The biopolysaccharide in step 1 is at least one of starch, seaweed polysaccharide, and lignin; In step 4, the adjuvant that inhibits the decrease in fertilizer particle strength is pulverized to 300-500 mesh before use. The pulverized adjuvant is then added to the raw materials for fertilizer production and granulated using conventional high-tower granulation. The amount of adjuvant added is 2-10% of the fertilizer weight.

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