Long-acting water-soluble alkali-adjusting fertilizer and preparation method thereof

Abstract

According to the long-acting water-soluble alkali-adjusting fertilizer and the preparation method thereof, raw materials of the long-acting water-soluble alkali-adjusting fertilizer are preferably selected from fully water-soluble materials, the product is fully water-soluble, the content of water-insoluble substances is smaller than 0.2% (G4 water-insoluble substance standard), and the long-acting water-soluble alkali-adjusting fertilizer is suitable for irrigation facilities such as drip irrigation facilities and sprinkling irrigation facilities; urea phosphate is used as a main acidic substance, so that the pH value of the product can be lower than 3.5 after the product is dissolved in water, and the effect of adjusting hard water is achieved; the raw material proportion is optimized, a certain amount of ammonium sulfate and powdery industrial monoammonium phosphate are used, meanwhile, the urea proportion is controlled, the use mode of ammonium bicarbonate after drying is matched, the system moisture is reduced, system dry-wet control is stabilized, the problem of screening deliquescence caused by system material acidity in the product production process is solved, and large-scale productivity is formed.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural fertilizers, and in particular to a long-acting water-soluble alkali-adjusting fertilizer and a preparation method thereof. Background Art

[0002] With the development and progress of agricultural facilities, the expansion of economic crop areas and the increase in labor costs, the demand for fully water-soluble fertilizers is increasing. In the drip irrigation system of saline-alkali land in the north, due to the high hardness of water, the impact of water used in drip irrigation on fertilizer utilization and facilities is relatively large. After long-term use, a scaling layer of calcium, magnesium and phosphorus will be formed inside the drip irrigation equipment, affecting the efficiency of fertilizer and water, and also affecting the efficiency of nutrient absorption. According to the water-soluble requirements of drip irrigation in saline-alkali land in the north, it does not block the filter, does not block the nozzle, and does not solidify the calcium and magnesium elements. The process and material ratio of environmentally friendly strong acidic raw materials that can be applied to agricultural production are optimized, and the technology of long-term alkali-adjusting water-soluble fertilizer products is developed under the drum granulation process. It can reduce the fixation of calcium, magnesium and phosphorus in fertilizers in hard water environments, and at the same time adjust the acidity and alkalinity of the soil around the roots, activate the activity of soil elements around the roots, improve fertilizer utilization, and meet the drip irrigation needs of saline-alkali land.

[0003] The compound fertilizers and their preparation processes currently on the market have the following problems: the pH of compound fertilizers is between 5.5 and 6.5, which cannot achieve the effect of regulating hard water. At the same time, it has little effect on the effectiveness of calcium and magnesium ions in hard water. Phosphate ions in fertilizers are easy to form precipitation with calcium and magnesium ions in water, resulting in nutrient loss; most of the alkali regulators on the market are soil conditioners, which have poor solubility and dispersibility. They are only used as base fertilizers and are not suitable for drip irrigation or sprinkler irrigation; slurry processes such as high tower processes are used, because they are mainly slurry. Adding too much acid will damage the equipment, and too little will not achieve the desired effect. , it is not easy to produce over-acid fertilizers; conventional materials used in the production of conventional drum process products are mostly sandy, and the acidity of existing materials is insufficient for alkali adjustment, resulting in low strength, poor granulation, easy compaction, pulverization, and poor water solubility, which cannot meet the long-term adjustment of water-soluble requirements; in the actual drum process, acidic materials are added to the production of fully water-soluble products. The acidity of the materials in the system during the production process causes the problem of screening and deliquescing water, which affects the unstable dry and wet control of the system, resulting in low yield and low production capacity; conventional water-soluble fertilizers are only quick-acting but not long-acting, and the fertilizer utilization rate is low; the surface humidity of the particles is relatively high during the production process, making it difficult to granulate.

[0004] Therefore, it is very necessary to develop a long-acting water-soluble alkali-adjusting fertilizer that can overcome the above-mentioned defects. In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a long-acting water-soluble alkali-adjusting fertilizer and a preparation method thereof. The long-acting water-soluble alkali-adjusting fertilizer can obtain a compound fertilizer that meets the nutrient requirements of crops in alkaline soil and has a pH value lower than 3.5 after being dissolved in water by optimizing the selection of raw materials. At the same time, the problem of screening deliquescence caused by the acidity of the system materials in the product production process is solved by optimizing the preparation process.

[0006] On the one hand, the present invention provides a long-acting water-soluble alkali-adjusting fertilizer, whose raw materials include: urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, γ-aminobutyric acid, 3,4-dimethylpyrazole phosphate and ammonium carbonate; the pH value of the long-acting water-soluble alkali-adjusting fertilizer after being dissolved in water is ≤3.5.

[0007] On the other hand, the present invention also provides a preparation method of the above-mentioned long-acting water-soluble alkali-adjusting fertilizer, which comprises: weighing urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, γ-aminobutyric acid and 3,4-dimethylpyrazole phosphate in proportion, adding part of ammonium carbonate after crushing and granulating, performing primary drying and secondary drying in sequence, and then adding the remaining part of ammonium carbonate, cooling, screening, powdering and spraying with oil to obtain the long-acting water-soluble alkali-adjusting fertilizer.

[0008] The present invention has the following beneficial effects:

[0009] The present invention adopts urea phosphate process optimization technology, and realizes stable system dry and wet control by optimizing raw material selection, raw material ratio, process technical parameters and technical route. Among them, the raw material is preferably a fully water-soluble material, the product is fully water-soluble, and the water-insoluble matter is less than 0.2% (G4 water-insoluble matter standard), which is suitable for irrigation facilities such as drip irrigation and sprinkler irrigation; urea phosphate is used as the main acidic substance, so that the pH value of the product after water dissolution can be lower than 3.5, thereby playing the effect of regulating hard water; optimize the raw material ratio and use a certain amount of ammonium sulfate and powdered industrial monoammonium phosphate, while controlling the urea ratio, matching the use of carbon ammonium after drying, reducing the system moisture, stabilizing the system dry and wet control, solving the problem of screening deliquescence caused by the acidity of the system materials in the product production process, and forming large-scale production capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 The present invention is a flow chart for preparing the long-acting water-soluble alkali-adjusting fertilizer.

[0012] Figure 2This is a finished product diagram of the long-acting water-soluble alkali-adjusting fertilizer of the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0014] A long-acting water-soluble alkali-adjusting fertilizer, the raw materials of which include the following components: urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, gamma-aminobutyric acid, 3,4-dimethylpyrazole phosphate (DMPP) and ammonium carbonate.

[0015] In order to reduce the loss of nutrients such as calcium and magnesium ions and obtain a compound fertilizer with a lower pH value to achieve the alkaline adjustment function, the present invention screens and compares a variety of acidic materials such as industrial monoammonium, urea sulfate, citric acid, etc., and finally screens out an acidic substance with urea phosphate as the main material, and compounding it with other materials to prepare a new compound fertilizer. It has been verified that the pH value of the fertilizer after being dissolved in water can be lower than 3.5.

[0016] The ingredients selected in the above fertilizers are all water-soluble materials, and the insoluble matter in the fertilizers prepared therefrom is less than 0.2% (G4 water-insoluble matter standard), so the fertilizers are more suitable for use in irrigation facilities such as drip irrigation and sprinkler irrigation.

[0017] The present invention chooses to add 3,4-dimethylpyrazole phosphate to the compound fertilizer because it is a water-soluble urease nitrification inhibitor. Adding an appropriate amount of 3,4-dimethylpyrazole phosphate can improve nutrient utilization, and adding 3,4-dimethylpyrazole phosphate to the fertilizer of the present invention can play a long-term role. Adding an appropriate amount of gamma-aminobutyric acid can promote root growth, resist stress and enhance synergy.

[0018] In some embodiments, the long-acting water-soluble alkali-adjusting fertilizer has the following raw material compositions by mass percentage: 10%-38% urea, 36%-56% potassium sulfate, 5%-26% industrial monoammonium, 0-32% ammonium sulfate, 3%-10% urea phosphate, 0.1%-0.5% zinc sulfate, 0.1%-0.5% boric acid, 0.1-0.5% γ-aminobutyric acid, 0.01-0.05% 3,4-dimethylpyrazole phosphate and 0.3-7% ammonium carbonate.

[0019] On the basis of the above-mentioned long-acting water-soluble alkali-adjusting fertilizer components, the present invention further optimizes the types and addition ratios of various raw materials to obtain the following scheme:

[0020] Urea 10%-38%, potassium sulfate 36%-56%, industrial monoammonium 5%-26%, ammonium sulfate 0-32%, urea phosphate 4%-5%, zinc sulfate 0.1%-0.2%, boric acid 0.1%-0.2%, gamma-aminobutyric acid 0.2%, 3,4-dimethylpyrazole phosphate 0.02% and ammonium carbonate 3%.

[0021] In some embodiments, the total nitrogen content of urea is ≥46.0%; potassium sulfate contains 50% potassium oxide; industrial monoammonium is industrial monoammonium 10-61-0, in which the nitrogen and phosphorus contents are 10% and 61%, respectively; ammonium sulfate is ammonium sulfate with a nitrogen content of 20%; urea phosphate is urea phosphate 17-44-0, in which the nitrogen and phosphorus contents are 17% and 44%, respectively; and ammonium carbonate is ammonium carbonate with a nitrogen content of 17%.

[0022] The total nutrient content of the long-acting water-soluble alkali-adjusting fertilizer prepared from the above raw materials is 40%-54%, of which the nitrogen nutrient content is 11%-18%, the phosphorus nutrient content is 5%-18%, and the potassium nutrient content is 18%-35%.

[0023] More preferably, the nitrogen nutrient content is 12%-15%, the phosphorus nutrient content is 5%-8%, and the potassium nutrient content is 25%-35%.

[0024] In order to solve the problems of screening deliquescence caused by the acidity of the system materials in the product production process, the present invention also correspondingly optimizes the preparation method of the above-mentioned long-acting water-soluble alkali-adjusting fertilizer. The schematic diagram of the preparation method is as follows Figure 1 As shown: urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, γ-aminobutyric acid and 3,4-dimethylpyrazole phosphate are weighed in proportion, crushed and granulated, and then part of ammonium carbonate is added, and primary and secondary drying are carried out in sequence, and then the remaining part of ammonium carbonate is added, and after cooling, screening, powdering and oil spraying, a long-acting water-soluble alkali-adjusting fertilizer is obtained.

[0025] In the present invention, the inventors optimize the addition amount of ammonium sulfate and industrial monoammonium, control the urea ratio, and then add ammonium carbonate in steps to reduce the moisture content of the system, stabilize the dry-wet control of the system, solve the problem of screening deliquescence caused by the acidity of the system materials in the product production process, and form large-scale production capacity.

[0026] The purpose of adding ammonium carbonate in steps is to neutralize the acidic substances on the surface of the particles in different stages, so that the dryness and wetness of the system materials can be controlled, thereby increasing the yield.

[0027] In some embodiments, when ammonium urea is added in two steps, the mass ratio of the ammonium urea added successively is 1:1-3; preferably, the mass ratio of the ammonium urea added successively is 1:2.

[0028] In some embodiments, the primary drying temperature is 170-260° C., and the secondary drying temperature is 95-120° C. More preferably, the primary drying temperature is 220° C., and the secondary drying temperature is 110° C.

[0029] The reason why the present invention adopts two-stage drying is that the high temperature of the first drying is to quickly increase the temperature of the material so that the moisture of the material can be dried, and the medium and low temperature of the second drying is to maintain the system temperature, which not only provides heat to the material to make the moisture continue to evaporate and decrease, but also makes the material slowly cool from a high temperature to a low temperature state, which can effectively reduce the subsequent cooling pressure and packaging temperature of the material; at the same time, it can alleviate the problem of water vaporization in the process of rapid cooling of high-moisture materials.

[0030] Compared with the existing process, the drying temperature of the primary drying and secondary drying adopted by the present invention is reduced by 30°C year-on-year. The advantages of lower drying temperature: reduced energy consumption; lower product material temperature, lower material packaging temperature, and improved anti-caking quality of finished products; it can greatly reduce the pyrophosphorylation reaction of phosphoric acid compounds, reduce the production of water-insoluble substances, and improve the water-soluble quality of products.

[0031] The fertilizer obtained by the above preparation method solves the problem that conventional compound fertilizers have no alkali adjustment function or the screening of deliquesced water caused by the addition of acidic materials in the system. It can also improve the unstable dry and wet control of the system, resulting in low strength, poor granulation, easy compaction, pulverization, and poor water solubility, resulting in low yield and low production capacity. A water-soluble compound fertilizer with alkali adjustment function is obtained.

[0032] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0033] Example 1

[0034] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is an 11-5-25 long-acting water-soluble fertilizer with a total nutrient content of 41%. The raw materials include: 10% urea (46%), 5% industrial monoammonium (10-61-0), 50% potassium sulfate (20%), 4% urea phosphate (17-44-0), 25.58% ammonium sulfate, 0.1% zinc sulfate, 0.2% boric acid, 0.1% γ-aminobutyric acid, 0.02% 3,4-dimethylpyrazole phosphate, and 5% urea carbonate (17%).

[0035] The preparation method of the above-mentioned long-acting water-soluble alkali-adjusting fertilizer is as follows: urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, γ-aminobutyric acid and 3,4-dimethylpyrazole phosphate are weighed in proportion, and one-third of ammonium carbonate is added after crushing and granulating, and primary drying and secondary drying are carried out in sequence, and then the remaining two-thirds of ammonium carbonate is added, and the long-acting water-soluble alkali-adjusting fertilizer is obtained after cooling, screening, powdering and oil spraying, wherein the primary drying temperature is 220°C and the secondary drying temperature is 110°C.

[0036] Example 2

[0037] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 12-5-26 long-acting water-soluble fertilizer with a total nutrient content of 43%. The raw materials are as follows: urea (46%) 12.68%, industrial monoammonium (10-61-0) 5%, potassium sulfate (20%) 52%, urea phosphate (17-44-0) 4%, ammonium sulfate 24%, zinc sulfate 0.1%, boric acid 0.1%, γ-aminobutyric acid 0.1%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 2%.

[0038] The preparation method is the same as that of Example 1.

[0039] Example 3

[0040] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 12-10-24 long-acting water-soluble fertilizer with a total nutrient content of 46%. The raw materials are as follows: urea (46%) 12.48%, industrial monoammonium (10-61-0) 14%, potassium sulfate (20%) 48%, urea phosphate (17-44-0) 4%, ammonium sulfate 18%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.2%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0041] The preparation method is the same as that of Example 1.

[0042] Example 4

[0043] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 12-5-32 long-acting water-soluble fertilizer with a total nutrient content of 49%. The raw materials are as follows: urea (46%) 23.58%, industrial monoammonium (10-61-0) 5%, potassium sulfate (20%) 64%, urea phosphate (17-44-0) 4%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.1%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0044] The preparation method is the same as that of Example 1.

[0045] Example 5

[0046] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 12-10-28 long-acting water-soluble fertilizer with a total nutrient content of 50%. The raw materials are as follows: urea (46%) 20%, industrial monoammonium (10-61-0) 14%, potassium sulfate (20%) 56%, urea phosphate (17-44-0) 4%, ammonium sulfate 2.58%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.1%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0047] The preparation method is the same as that of Example 1.

[0048] Example 6

[0049] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 15-10-20 long-acting water-soluble fertilizer with a total nutrient content of 45%. The raw materials are as follows: urea (46%) 18.58%, industrial monoammonium (10-61-0) 14%, potassium sulfate (20%) 40%, urea phosphate (17-44-0) 4%, ammonium sulfate 18%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.1%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 5%.

[0050] The preparation method is the same as that of Example 1.

[0051] Example 7

[0052] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 15-15-15 long-acting water-soluble fertilizer with a total nutrient content of 45%. The raw materials are as follows: urea (46%) 14.58%, industrial monoammonium (10-61-0) 22%, potassium sulfate (20%) 30%, urea phosphate (17-44-0) 4%, ammonium sulfate 24%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.1%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 5%.

[0053] The preparation method is the same as that of Example 1.

[0054] Example 8

[0055] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 17-5-18 long-acting water-soluble fertilizer with a total nutrient content of 40%. The raw materials are as follows: urea (46%) 22%, industrial monoammonium (10-61-0) 5%, potassium sulfate (20%) 36%, urea phosphate (17-44-0) 4%, ammonium sulfate 29.58%, zinc sulfate 0.1%, boric acid 0.1%, γ-aminobutyric acid 0.2%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0056] The preparation method is the same as that of Example 1.

[0057] Example 9

[0058] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 17-17-17 long-acting water-soluble fertilizer with a total nutrient content of 51%. The raw materials are as follows: urea (46%) 26%, industrial monoammonium (10-61-0) 25%, potassium sulfate (20%) 34%, urea phosphate (17-44-0) 4%, ammonium sulfate 7.58%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.2%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0059] The preparation method is the same as that of Example 1.

[0060] Example 10

[0061] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is an 18-18-18 long-acting water-soluble fertilizer with a total nutrient content of 51%. The raw materials are as follows: 30.48% urea (46%), 28% industrial monoammonium (10-61-0), 36% potassium sulfate (20%), 3% urea phosphate (17-44-0), 0.1% zinc sulfate, 0.2% boric acid, 0.2% γ-aminobutyric acid, 0.02% 3,4-dimethylpyrazole phosphate, and 2% urea carbonate (17%).

[0062] The preparation method is the same as that of Example 1.

[0063] Embodiment 11

[0064] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is an 18-5-20 long-acting water-soluble fertilizer with a total nutrient content of 43%. The raw materials are as follows: urea (46%) 28.48%, industrial monoammonium (10-61-0) 5%, potassium sulfate (20%) 40%, urea phosphate (17-44-0) 4%, ammonium sulfate 19%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.2%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0065] The preparation method is the same as that of Example 1.

[0066] Example 12

[0067] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is an 18-5-26 long-acting water-soluble fertilizer with a total nutrient content of 43%. The raw materials are as follows: 37.7% urea (46%), 5.48% industrial monoammonium (10-61-0), 52% potassium sulfate (20%), 4% urea phosphate (17-44-0), 0.1% zinc sulfate, 0.2% boric acid, 0.2% γ-aminobutyric acid, 0.02% 3,4-dimethylpyrazole phosphate, and 3% urea carbonate (17%).

[0068] The preparation method is the same as that of Example 1.

[0069] Embodiment 13

[0070] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is an 18-5-26 long-acting water-soluble fertilizer with a total nutrient content of 51%. The raw materials are as follows: 30% urea (46%), 12% industrial monoammonium (10-61-0), 52% potassium sulfate (20%), 4% urea phosphate (17-44-0), 1.18% ammonium sulfate, 0.1% zinc sulfate, 0.2% boric acid, 0.2% γ-aminobutyric acid, 0.02% 3,4-dimethylpyrazole phosphate, and 0.3% ammonium carbonate (17%).

[0071] The preparation method is the same as that of Example 1.

[0072] Embodiment 14

[0073] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 14-4-32 long-acting water-soluble fertilizer with a total nutrient content of 50%. The raw materials are as follows: urea (46%) 25.08%, industrial monoammonium (10-61-0) 6%, potassium sulfate (20%) 64%, urea phosphate (17-44-0) 3%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.1%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 1.5%.

[0074] The preparation method is the same as that of Example 1.

[0075] Embodiment 15

[0076] The present embodiment is a long-acting water-soluble alkali-adjusting fertilizer, which is a 15-5-26 long-acting water-soluble fertilizer with a total nutrient content of 50%. The raw materials are as follows: urea (46%) 23%, industrial monoammonium (10-61-0) 5%, potassium sulfate (20%) 50%, urea phosphate (17-44-0) 4%, ammonium sulfate 14.4%, zinc sulfate 0.1%, boric acid 0.2%, γ-aminobutyric acid 0.28%, 3,4-dimethylpyrazole phosphate 0.02%, and ammonium carbonate (17%) 3%.

[0077] The preparation method is the same as that of Example 1.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that urea phosphate is replaced by an equal amount of urea sulfate.

[0080] Comparative Example 2

[0081] The difference from Example 6 is that urea phosphate is replaced by an equal amount of citric acid.

[0082] Comparative Example 3

[0083] The difference from Example 15 is that 3,4-dimethylpyrazole phosphate was not added.

[0084] Comparative Example 4

[0085] The difference from Example 10 is that ammonium carbonate is mixed with other materials at the same time.

[0086] Comparative Example 5

[0087] The difference from Example 5 is that all the ammonium carbonate is added during primary drying.

[0088] Comparative Example 6

[0089] The difference from Example 8 is that the ratio of ammonium carbonate added before and after is changed from 1:2 to 3:1.

[0090] Comparative Example 7

[0091] The difference from Example 11 is that agricultural monoammonium phosphate is used instead of industrial monoammonium phosphate.

[0092] Experimental example

[0093] The fertilizers prepared in the examples and comparative examples were tested for relevant indicators, including pH value, strength, water-insoluble matter content, yield rate and nitrification inhibition rate of the fertilizer particles.

[0094] The granule pH test is based on NY / T1973-2021 Determination of water-insoluble matter content and pH of water-soluble fertilizers, as follows:

[0095] Before the measurement, set the pH meter temperature compensation system to 25°C and calibrate the pH meter using pH standard buffer. Weigh 1g of sample (accurate to 0.001g) and place it in a beaker, add 250mL of decarbonated water, stir thoroughly for 3min, let stand for 15min, immerse the electrode in the solution to avoid bubbles, and record the pH after the instrument reading stabilizes. Rinse the electrode with water after the measurement.

[0096] Strength test: The fertilizers prepared in the examples and comparative examples were placed in a fertilizer particle strength tester to test their strength.

[0097] The water-insoluble content test refers to NY / T1973-2021 Determination of water-insoluble content and pH of water-soluble fertilizers, as follows:

[0098] At room temperature, weigh 1g of sample (accurate to 0.001g), place it in a beaker, add 250mL of water, stir thoroughly for 3min, let stand for 15min, and then filter with a glass crucible filter that has been dried to constant weight in a 110℃ drying oven. When transferring by suction, first pour the upper layer of solution in the beaker, shake until a small amount of solution (about 20mL) remains at the bottom, then pour it into the filter, and finally rinse the beaker with a small amount of water (no more than 50mL) to transfer all the residue into the filter. Place the filter with the residue in a drying oven, dry it for 1h after the temperature reaches 110℃, take it out and move it into a desiccator, cool it to room temperature, and weigh it (accurate to 0.001g). The blank test is the same as the sample determination except that no sample is added.

[0099] The water-insoluble content is expressed as ω, and the value is expressed as mass fraction (%), and is calculated according to the following formula: ω = (m 1 -m 0 ) / m×100%; where m 1 -The mass value of water-insoluble matter, in grams; m0 -The mass value of water-insoluble matter in blank test, in grams; m 1 -The mass value of the sample, in grams. The arithmetic mean of the parallel determination results is taken as the determination result.

[0100] Nitrification inhibition rate is an indicator for evaluating the long-term performance of fertilizers. The higher the nitrification inhibition rate, the better the long-term effect of the fertilizer. The detection method is based on the GBT35113-2017 stability standard, as follows:

[0101] Add 5mL of boric acid-indicator to a 50mL No. 1 triangular flask, place it under the condenser of the nitrogen distillation device, draw 10mL of the filtrate after soil extraction into the distillation device, add 0.2g of magnesium oxide, heat immediately, and distill at a rate of 6mL / min~8mL / min until the distillate reaches the 30mL line, and wash the lower part of the cooling tube with a small amount of distilled water, and remove the No. 1 triangular flask. Use a No. 2 triangular flask with 5mL of boric acid-indicator at the lower end of the condenser, quickly add 0.2g of nitrogen alloy powder to the distillation flask, distill again, and stop when the distillate reaches the 30mL line, and wash the lower part of the cooling tube with a small amount of distilled water. Use a microtitrator to titrate the distillate in the No. 2 flask with a standard sulfuric acid solution, and determine the nitrate nitrogen (including nitrite nitrogen) content in the sample and control sample soils, respectively. The color is green and the endpoint is slightly red. The control sample is a fertilizer that does not contain 3,4-dimethylpyrazole phosphate.

[0102] The nitrate nitrogen (including nitrite nitrogen) content in the soil is expressed in milligrams per kilogram (mg / kg) and is calculated as follows:

[0103]

[0104] Where, V- is the volume of sulfuric acid standard solution consumed during the determination, in milliliters (mL);

[0105] V 0 -The volume of sulfuric acid standard solution consumed in the blank test, in milliliters (mL);

[0106] C2-sulfuric acid (1 / 2H 2 SO 4 ) is the numerical value of the standard solution concentration, in moles per liter (mol / L);

[0107] M-the numerical value of the molar mass of nitrogen, M(N)=14.01 g / mol;

[0108] ts-multiples;

[0109] m ± - Numerical value of soil mass in grams (g);

[0110] w-soil moisture content (analytical basis), %.

[0111] The nitrification inhibition rate dN, expressed as 5, is calculated according to the following formula:

[0112] dN=(ω 2 -ω 1 ) / ω 2 ×100%; where ω 2 is the nitrate nitrogen (including nitrite nitrogen) of the control sample, %; ω 1 is the nitrate nitrogen (including nitrite nitrogen) of the sample, %.

[0113] The yield rate is calculated by calculating the ratio of the actual weight of qualified particles produced to the total weight of input raw materials.

[0114] The test results are as follows:

[0115] Table 1 Particle acidity and water solubility

[0116]

[0117] Table 2 Comparison of the pH and water solubility of the particles

[0118]

[0119] According to the test results in Table 1 and Table 2, it can be concluded that, compared with the comparative example, the pH value of the fertilizer prepared in the embodiment can reach about 3.0, and can also maintain good strength, water solubility and yield rate, and also has excellent nitrification inhibition rate.

[0120] Figure 2 This is a picture of the finished fertilizer prepared in Example 15, from which it can be seen that the long-acting water-soluble alkali-adjusting fertilizer of the present invention has good granulation properties and can obtain a finished product.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A long-acting water-soluble alkali-adjusting fertilizer, characterized in that: The raw materials of the long-acting water-soluble alkali-adjusting fertilizer include: urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, γ-aminobutyric acid, 3,4-dimethylpyrazole phosphate and ammonium carbonate; the pH value of the long-acting water-soluble alkali-adjusting fertilizer after being dissolved in water is ≤3.

5.

2. The long-acting water-soluble alkali-adjusting fertilizer according to claim 1, characterized in that: The total nutrient content of the long-acting water-soluble alkali-adjusting fertilizer is 40%-54%, wherein the nitrogen nutrient content is 11%-18%, the phosphorus nutrient content is 5%-18%, and the potassium nutrient content is 18%-35%.

3. The long-acting water-soluble alkali-adjusting fertilizer according to claim 2, characterized in that: The long-acting water-soluble alkali-adjusting fertilizer has a nitrogen nutrient content of 12%-15%, a phosphorus nutrient content of 5%-8%, and a potassium nutrient content of 25%-35%.

4. The long-acting water-soluble alkali-adjusting fertilizer according to claim 3, characterized in that: The raw material composition of the long-acting water-soluble alkali-adjusting fertilizer is as follows in terms of mass percentage: Urea 10%-38%, potassium sulfate 36%-56%, industrial monoammonium 5%-26%, ammonium sulfate 0-32%, urea phosphate 3%-10%, zinc sulfate 0.1%-0.5%, boric acid 0.1%-0.5%, γ-aminobutyric acid 0.1-0.5%, 3,4-dimethylpyrazole phosphate 0.01-0.05% and ammonium carbonate 0.3-7%.

5. The long-acting water-soluble alkali-adjusting fertilizer according to claim 4, characterized in that: The total nitrogen content of the urea is ≥46.0%; the potassium sulfate contains 50% potassium oxide; the industrial monoammonium is industrial monoammonium 10-61-0; the ammonium sulfate is ammonium sulfate with a nitrogen content of 20%; the urea phosphate is urea phosphate 17-44-0; and the ammonium carbonate is ammonium carbonate with a nitrogen content of 17%.

6. The long-acting water-soluble alkali-adjusting fertilizer according to claim 5, characterized in that: The mass percentage of urea phosphate in the long-acting water-soluble alkali-adjusting fertilizer is 4%-5%; Preferably, the mass percentage of zinc sulfate is 0.1%-0.2%; Preferably, the mass percentage of boric acid is 0.1%-0.2%; Preferably, the mass percentage of γ-aminobutyric acid is 0.2%; Preferably, the mass percentage of 3,4-dimethylpyrazole phosphate is 0.02%; Preferably, the mass percentage of ammonium carbonate is 3%.

7. The method for preparing the long-acting water-soluble alkali-adjusting fertilizer according to any one of claims 1 to 6, characterized in that: include: Urea, potassium sulfate, industrial monoammonium, ammonium sulfate, urea phosphate, zinc sulfate, boric acid, γ-aminobutyric acid and 3,4-dimethylpyrazole phosphate are weighed in proportion, crushed and granulated, and then part of ammonium carbonate is added, and primary drying and secondary drying are carried out in sequence, and then the remaining part of ammonium carbonate is added, and the long-acting water-soluble alkali-adjusting fertilizer is obtained after cooling, screening, powdering and oil spraying.

8. The preparation method according to claim 7, characterized in that: The temperature of the primary drying is 170-260°C, and the temperature of the secondary drying is 95-120°C.

9. The preparation method according to claim 8, characterized in that: The primary drying temperature is 220°C, and the secondary drying temperature is 110°C.

10. The preparation method according to claim 7, characterized in that: The mass ratio of the two additions of ammonium carbonate is 1:1-3; Preferably, the mass ratio of the two additions of ammonium carbonate is 1:2.

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