CN116178076A - Granulation method for preparing compound fertilizer by chelating urea sulfate - Google Patents

Granulation method for preparing compound fertilizer by chelating urea sulfate Download PDF

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CN116178076A
CN116178076A CN202211339233.5A CN202211339233A CN116178076A CN 116178076 A CN116178076 A CN 116178076A CN 202211339233 A CN202211339233 A CN 202211339233A CN 116178076 A CN116178076 A CN 116178076A
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urea
compound fertilizer
urea sulfate
sulfuric acid
chelating
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严玉虎
张�杰
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Zhongsheng Nanyang Biotechnology Co Ltd
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Zhongsheng Nanyang Biotechnology Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B17/00—Other phosphatic fertilisers, e.g. soft rock phosphates, bone meal
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
    • C05G3/40—Mixtures of one or more fertilisers with additives not having a specially fertilising activity for affecting fertiliser dosage or release rate; for affecting solubility
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
    • C05G3/90—Mixtures of one or more fertilisers with additives not having a specially fertilising activity for affecting the nitrification of ammonium compounds or urea in the soil
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G5/00—Fertilisers characterised by their form
    • C05G5/10—Solid or semi-solid fertilisers, e.g. powders
    • C05G5/12—Granules or flakes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
    • Y02P60/20—Reduction of greenhouse gas [GHG] emissions in agriculture, e.g. CO2
    • Y02P60/21—Dinitrogen oxide [N2O], e.g. using aquaponics, hydroponics or efficiency measures

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Pest Control & Pesticides (AREA)
  • Soil Sciences (AREA)
  • Fertilizers (AREA)

Abstract

The invention provides a granulating method for preparing a compound fertilizer by chelating urea sulfate, belonging to the technical field of compound fertilizers. The granulating method for preparing the compound fertilizer by chelating urea sulfate comprises the following steps: s01, mixing and grinding ground phosphate rock powder and sulfuric acid, and adding urea to obtain a composite material I; s02, adding potassium chloride into the composite material I, mixing, and crushing to obtain a composite material II; s03, mixing and granulating the liquid urea sulfate and the composite material II, and drying to obtain the product. The granulation method for preparing the compound fertilizer by chelating urea sulfate improves the quality and the granulation rate of the compound fertilizer.

Description

Granulation method for preparing compound fertilizer by chelating urea sulfate
Technical Field
The invention belongs to the technical field of compound fertilizers, and particularly relates to a granulating method for manufacturing a compound fertilizer by chelating urea sulfate.
Background
The compound fertilizer is an important material foundation for guaranteeing sustainable development of grain production, and plays an important role in grain safety. Agricultural fertilization and irrigation practices of countries around the world show that in order to ensure that crops are stable and high-yield crops can obtain enough nutrients, especially nitrogen nutrients, in the whole growth period, the fertilization amount per unit area of China is 3 times of the average world level, but the nitrogen fertilizer utilization rate is only about 50% of the average developed world level. Therefore, the method has important practical significance for improving the nitrogen utilization rate in the compound fertilizer.
The research shows that the urea sulfate compound fertilizer has positive effect on improving the nitrogen utilization rate, is acidic and has beneficial effect on improving the saline-alkali soil. Urea sulfuric acid compound fertilizer is one of various kinds of compound fertilizer, and is attracting more and more attention due to the advantages of resource utilization, product effect, environmental protection and the like brought by the production process. In the production of urea sulfate-containing compound fertilizers, urea sulfate is the basic production raw material. The urea sulfate can be applied as an acidic fertilizer containing nitrogen and sulfur, and can reduce volatilization of ammonium nitrogen in a soil plough layer and reduce loss of nitrogen. Numerous studies have shown that urea sulfate is more effective than urea alone and safer than ammonium sulfate alone. The appearance of the urea sulfate-containing compound fertilizer has important significance for improving the comprehensive utilization rate of nutrients, improving soil, repairing soil and further realizing scientific and reasonable fertilization, and has very broad market prospect.
In addition, the cost of raw materials for phosphorus elements such as monoammonium phosphate has been increasing year by year, and alternative raw materials are being continuously researched and developed. The known phosphorite resources in China are rich in reserves, but the phosphorite is mainly used in medium and low grade (the phosphorus pentoxide content is lower than 28%), the ore dressing is difficult and the cost is high. Meanwhile, the phosphorite is too concentrated in distribution, and the transportation cost of enterprises is greatly increased. Along with the continuous consumption of phosphorus resources, development and utilization of medium-low grade phosphorus ores are of great significance for fully utilizing phosphorus resources in China, reducing the production cost of enterprises and promoting sustainable development of phosphorus chemical industry.
In the prior art, patent document CN101508607A discloses a preparation method of urea sulfuric acid long-acting slow-release compound fertilizer, which comprises the steps of decomposing activated phosphate rock powder with sulfuric acid to prepare active slurry, reacting with urea to prepare composite slurry, neutralizing the composite slurry with alkaline weathered coal slurry, delivering the composite slurry to a rotary drum granulator to granulate with potassium chloride, filler, proper amount of urea and returned material, and drying to obtain the granular urea sulfuric acid long-acting slow-release compound fertilizer. For another example, patent document CN108558556a discloses a method for preparing a granular urea-based compound fertilizer by decomposing powdered rock phosphate with urea sulfuric acid, which comprises the steps of preparing an aqueous solution of urea sulfuric acid, decomposing the powdered rock phosphate, adding a physical property regulator, granulating and the like. The conversion rate of the rock phosphate powder of the method reaches more than 80 percent; the gas-phase fluorine escape rate is reduced to below 7% from 40% of the original acid-mine reaction, so that the unorganized emission of fluorine and the environmental treatment cost are effectively reduced; by adding the physical property regulator, the problem that the nitrogen-phosphorus binary fertilizer slurry can be directly used as an independent nitrogen-phosphorus binary fertilizer or used as a compound fertilizer production additive material is solved; the fluorine in the granular urea-based compound fertilizer exists in the form of fluosilicic acid urea, has the functions of pesticide and disinsection, reduces the dosage of chemical pesticide, saves cost and increases efficiency. The analysis and experimental study show that the quality stability of the compound fertilizer is not high, the granulation rate is low, and the compound fertilizer needs to be improved.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a granulating method for preparing a compound fertilizer by chelating urea sulfate, so as to improve the quality and the granulating rate of the compound fertilizer.
In order to solve the technical problems, the invention adopts the following technical scheme: the granulating method for preparing the compound fertilizer by chelating urea sulfate comprises the following steps:
s01, mixing and grinding ground phosphate rock powder and sulfuric acid, and adding urea to obtain a composite material I;
s02, adding potassium chloride into the composite material I, mixing, and crushing to obtain a composite material II;
s03, mixing and granulating the liquid urea sulfate and the composite material II, and drying to obtain the product.
Preferably, in the step S01, the mass fraction of the sulfuric acid is 72-80%, the grinding time is 18-25min, the grinding pressure is 10-15MPa, and the grinding rotating speed is 80-120r/min.
Optionally, the mass fraction of sulfuric acid is 72%, 73%, 75%, 78% or 80%; grinding for 18min, 19min, 20min, 21min, 22min, 23min, 24min or 25min; the grinding pressure is 10MPa, 11MPa, 12MPa, 13MPa, 14MPa or 15MPa, and the grinding rotating speed is 80r/min, 85r/min, 90r/min, 95r/min, 100r/min, 105r/min, 110r/min, 115r/min or 120r/min. Under the grinding condition, the grinding force and the rotating speed are proper, the ground phosphate rock fully contacts with sulfuric acid, the reaction is more complete, and meanwhile, no idle work is generated, the vibration of materials is increased, and the reaction efficiency is reduced.
Preferably, in the S01, the weight ratio of the ground phosphate rock, the sulfuric acid and the urea is 100: (86-92): (7-30).
Optionally, the weight ratio of the ground phosphate rock to the sulfuric acid to the urea is 100:86: 7. 100:87: 10. 100:88: 15. 100:89: 18. 100:90:20. 100:90: 23. 100:91: 25. 100:92:28 or 100:92:30.
in S01, the dosage of sulfuric acid is 100-110 percent (for example, 100%, 101%, 103%, 105%, 107%, 108% or 110%) of the theoretical dosage, the grinding time is 18-25min (for example, 18min, 19min, 20min, 21min, 23min or 25 min), the mass fraction of sulfuric acid is 72-80% (for example, 60%, 61%, 62%, 63%, 65%, 67%, 69% or 70%), the effective phosphorus content (calculated by phosphorus pentoxide) in the obtained composite material is obviously improved, and the phosphorus conversion rate can reach more than 85%.
Preferably, the urea sulfate has a viscosity of 1000-2000 mPas (e.g., 1000 mPas, 1100 mPas, 1200 mPas, 1500 mPas, 1600 mPas, 1800 mPas or 2000 mPas) at 20℃and a pH of 6.0-6.3 (e.g., 6.0, 6.1, 6.2 or 6.3).
Preferably, the urea sulfate is made of urea, sulfuric acid and water, the molar ratio of the urea, the sulfuric acid and the water being (1.5-3.5): 1:1.
optionally, the molar ratio of urea, sulfuric acid, and water is 1.5:1: 1. 1.6:1: 1. 1.8:1: 1. 2.0:1: 1. 2.1:1: 1. 2.3:1: 1. 2.5:1: 1. 2.8:1: 1. 3.0:1: 1. 3.2:1:1 or 3.5:1:1. the urea, sulfuric acid and water are adopted to react in a specific proportion, the viscosity and pH of the obtained urea sulfate are more favorable for granulation, and the granulating effect of products outside the proportion range is obviously inferior to that of the invention.
Preferably, the preparation method of the urea sulfate comprises the following steps: mixing urea with water for dissolution, and slowly adding sulfuric acid into urea aqueous solution for reaction to obtain liquid urea sulfate.
In the preparation of urea sulfate, the sulfuric acid consumption is 105-125% of theoretical consumption, and the molar ratio of urea, sulfuric acid and water is (1.5-3.5): 1:1, the reaction temperature is 60-70 ℃, the reaction time is 20-25min, the stirring speed is 700-750r/min, the mass fraction of sulfuric acid is 90-98 ℃, and the conversion rate of urea sulfuric acid to phosphorite can reach 96.25% under the process condition.
In S02, crushing is carried out by using crushing equipment commonly used in the technical field and sold in the market at present, and crushing the mixture of the composite material I and potassium chloride to ensure that the particle size is smaller than 5mm.
Preferably, in S03, the granulating temperature is 65-75deg.C (e.g., 65deg.C, 68deg.C, 70deg.C, 71 deg.C, 72 deg.C, 73 deg.C or 75deg.C). The specific granulating temperature and the material particle size are beneficial to improving the granulating efficiency, granulating quality and granulating strength of the urea sulfate.
In S03, the drying is performed using a drying apparatus commonly used in the art and currently marketed, so that the water content of the granulated product is less than 2.0%.
Preferably, the particle size of the ground phosphate rock is not more than 80 mesh.
The ground phosphate rock can be crushed and screened before use, so that the granularity of the ground phosphate rock is uniform, the ground phosphate rock can be fully contacted with sulfuric acid, and the reaction efficiency is improved.
Preferably, the granulation method for preparing the compound fertilizer by chelating urea sulfate further comprises the following steps:
and adding medium and trace elements into the composite material II.
Wherein, the moderate trace elements can be added in proper amount according to the crop demand, and other common moderate trace elements also comprise: more than one of calcium, magnesium, manganese, iron, zinc, molybdenum, cobalt and boron. For example, calcium, magnesium, manganese, iron, zinc, molybdenum, cobalt, or boron, or a combination of two or more of the foregoing elements.
The invention also provides a urea sulfate chelating compound fertilizer prepared by the granulation method, wherein the total nutrient (N+P) 2 O 5 +K 2 The mass fraction of O) is more than or equal to 30 percent, the mass fraction of sulfur (S) is more than or equal to 13 percent, and the percentage of amide nitrogen accounting for the total nitrogen is more than or equal to 70 percent.
As described in the background art, the phosphorite in China is mainly middle-low grade phosphorite, and the treatment method of the middle-low grade phosphorite is mainly concentrated on the aspects of flotation treatment, acid leaching, thermal calcination, direct application and the like. At present, researches show that the problems of resource waste, environmental pollution, production cost improvement and the like cannot be avoided no matter the medium-low grade phosphorite is treated by an acid method, a thermal method and a floatation method and then is used, or the phosphorite is directly applied as a fertilizer.
The research on low-grade phosphorite in sulfuric acid process treatment is earlier, but the low-grade phosphorite is difficult to apply in industry. The method comprises the steps of mixing and soaking the medium-low grade phosphorite with sulfuric acid with a certain concentration to remove magnesium and other impurities contained in the phosphorite, so that the phosphorite is purified, the loss of phosphorus is large in the magnesium removal process, the regularity of experimental results is poor, the decomposition capacity of sulfuric acid is strong, the sulfuric acid cannot be effectively selected, and a large amount of phosphorus element is lost due to the reaction between the sulfuric acid and phosphorite during the decomposition of magnesium carbonate; meanwhile, a phenomenon of overlarge local concentration difference is often generated in the reaction container, so that the selectivity of the reaction is poor, and stable production operation indexes are difficult to realize; the existence of these problems greatly limits the application of the sulfuric acid process in practical production. Therefore, in order to directly utilize the phosphate rock powder for the production of the compound fertilizer, the phosphate rock powder needs to be treated from the utilization angle of the compound fertilizer, and the thought is changed to overcome the problems.
In addition, in the consumption structure of phosphate ores in China, about 70% of the ore for agricultural chemical fertilizer is about, and the rest 30% of the ore is generally used for extracting yellow phosphorus, phosphoric acid and manufacturing other phosphate series products, and most of the series products are products with low technical content, large resource consumption and low added value. Therefore, the comprehensive utilization rate of the phosphorite is obviously not high, and the utilization difficulty of the phosphorite is reflected to be high. Among them, the technology of decomposing phosphorite by urea sulfate to produce compound fertilizer has the advantages of obviously improving the conversion rate of phosphorus, the content of available phosphorus, the content of nitrogen and the like, and is valued in the industry. In the prior art, CN101508607A is prepared by mixing powdered rock phosphate with water, reacting with concentrated sulfuric acid, adding urea, neutralizing with alkaline weathered coal slurry, spraying a granulator, mixing with solid materials, granulating, drying, screening to obtain a finished product, wherein the water-soluble phosphorus content of the finished product obtained by the technology is higher, which indicates that the treatment effect of the powdered rock phosphate is better, but the pH value is regulated by adding the alkaline weathered coal slurry prepared from weathered coal, alkali liquor, urea and water before granulating. CN108558556A is prepared by directly adding powdered rock phosphate into aqueous solution of urea sulfate for reaction, and then blending and granulating, and the method can lead the conversion rate of phosphorus in the powdered rock phosphate to reach 80%, and has no need of improving other nutrient indexes and granulating effect in the compound fertilizer.
In this regard, the granulation effect of the urea sulfate compound fertilizer plays an important role in improving the quality of the compound fertilizer. The production efficiency of the granulating device is determined by the granulating rate, the production cost and popularization and application thereof are critical, and the properties of the granules obtained by granulating have important influence on transportation and application effects thereof, such as active ingredient content, slow release and the like. Therefore, the granulation process and parameters thereof need to be explored and studied for different materials. In the granulating process of compound fertilizer, the characteristics of binder, including viscosity, are key parameters, which affect the appearance, performance, transportation, storage and other aspects of the product, and are of great concern. Today, with the development of urea sulfate compound fertilizers, the treatment of urea sulfate and phosphate rock powder and the preparation of related compound fertilizers are also closely related, and are also in continuous development and change. Liquid urea sulfate is often used as a binder or treating agent, the viscosity of which varies greatly under different reaction conditions, and has unpredictable effects on the binding granulation of materials, the treatment effect of the materials and the like.
Therefore, the process for preparing the urea sulfate compound fertilizer is researched, the quality of the product is concerned, meanwhile, the factors such as the controllability, the stability and the feasibility of the process are also particularly concerned, and the comprehensive consideration is carried out, so that the compound fertilizer with high quality and good granulating effect is developed from the aspect of the integrity, and the effectiveness and the convenience of use, transportation and storage are better met.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a granulating method for preparing the compound fertilizer by chelating urea sulfate based on the technical scheme, and the compound fertilizer obtained by the method has high quality, high granulating rate and convenient storage and transportation; the urea sulfate compound fertilizer product is dissolved in water to form uniform suspension in the liquid, has unique heat preservation and nitrogen preservation slow release effects, and can slow down nitrogen loss to a certain extent.
Firstly, the reaction of the ground phosphate rock and the sulfuric acid is solid-liquid two-phase reaction, grinding is carried out to promote the contact of the ground phosphate rock and the sulfuric acid, so that the reaction is more complete, wherein the mass fraction of the sulfuric acid is preferably 60-70%, the dosage of the sulfuric acid is 100-110% of the theoretical dosage, the grinding time is preferably 18-25min, the reaction is more complete, and the effective rate content of the product is obviously increased; the invention has reasonable control of the sulfuric acid consumption, can not cause excessive free acid in the product, and can facilitate the subsequent processing of the product, wherein the content of the free acid is below 9%.
Secondly, adding potassium chloride to increase fertilizer efficiency, and enabling the potassium chloride and the first composite material to coexist stably, wherein the temperature is controlled below 60 ℃, preferably 50-60 ℃, the humidity is controlled below 30%, and the granulating time is 8-12min, so that volatilization of effective elements is avoided, moisture absorption is reduced, and the storage performance of the compound fertilizer is improved.
And thirdly, the liquid urea sulfate has more outstanding cohesive granulation effect on the second composite material, so that the second composite material is more granulated with higher granulation efficiency, and the granulation rate is higher than 90%.
The preparation steps are matched with each other and interact to form the granulation method for preparing the compound fertilizer by chelating urea sulfate as a whole, thereby providing favorable support for improving the quality of the compound fertilizer and enhancing the granulation effect. The granulation method for preparing the compound fertilizer by chelating urea sulfate of the invention obtains total nutrient (N+P) in the compound fertilizer 2 O 5 +K 2 The mass fraction of O) is more than or equal to 30%, the percentage of water-soluble phosphorus occupied by available phosphorus is more than or equal to 70%, the mass fraction of sulfur (S) is more than or equal to 13%, the percentage of ammonia volatile nitrogen occupied by total nitrogen is less than 15%, the percentage of amide nitrogen occupied by total nitrogen is more than or equal to 70%, and the quality is high.
In addition, the particle strength of the compound fertilizer is used as an important index for measuring the particle properties of the compound fertilizer, the higher particle strength is beneficial to transportation, storage and the like of the particles, the particles are not easy to crush, the effective components are not easy to lose, and the particle strength of the compound fertilizer is more than 40N; meanwhile, the granulation rate is an important standard for judging whether the granulation process is applicable and popularized, and the particle mass of the compound fertilizer product prepared by the invention with the particle diameter standard (1-4.75 mm) accounts for more than 90% of the total mass of the used granulation raw materials, so that the urea sulfate chelating compound fertilizer is very applicable and convenient to popularize.
Detailed Description
For a better understanding of the present invention, the following examples are set forth to further illustrate the invention, but are not to be construed as limiting the invention. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without one or more of these details.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values.
Unless otherwise indicated, all starting materials are from commercially available products and unless otherwise indicated, they do not contain other components not explicitly indicated except for unavoidable impurities.
In the following examples, K in Potassium chloride 2 The mass fraction of O is 60%; the mesh number of the phosphate rock powder is 80 meshes, and the phosphorus pentoxide content is 18%.
Example 1: preparation of composite one
Providing ground phosphate rock, sulfuric acid and urea; adding 75% sulfuric acid into ground phosphate rock, wherein the grinding pressure is 12MPa, and the grinding rotating speed is 100r/min, and grinding for 20min; adding urea to obtain a first composite material; wherein, the mass ratio of the ground phosphate rock to the sulfuric acid to the urea is 100:90:20.
the effective phosphorus content in composite one was measured to be 12.05% with a phosphorus conversion of 86.06%.
Example 2: preparation of composite one
Providing ground phosphate rock, sulfuric acid and urea; taking ground phosphate rock, adding sulfuric acid with the mass fraction of 72%, grinding at the pressure of 10MPa and the grinding rotating speed of 120r/min for 18min; adding urea to obtain a first composite material; wherein, the mass ratio of the ground phosphate rock to the sulfuric acid to the urea is 100:92:13.
the effective phosphorus content in composite one was measured to be 11.38% and the conversion of phosphorus was 84.57%.
Example 3: preparation of composite one
Providing ground phosphate rock, sulfuric acid and urea; adding 80% sulfuric acid into ground phosphate rock, wherein the grinding pressure is 15MPa, and the grinding rotating speed is 80r/min, and grinding for 25min; adding urea to obtain a first composite material; wherein, the mass ratio of the ground phosphate rock to the sulfuric acid to the urea is 100:86:27.
the effective phosphorus content in composite one was measured to be 11.52% with a phosphorus conversion of 85.21%.
Example 4: preparation of liquid urea sulfate
Providing sulfuric acid, urea and water, mixing and dissolving the urea and the water, slowly adding the sulfuric acid into a urea water solution for reaction to obtain liquid urea sulfate; wherein the mass fraction of sulfuric acid is 95 ℃, and the molar ratio of urea to sulfuric acid to water is 3.2:1:1, the reaction temperature is 65 ℃, the reaction time is 23min, and the stirring speed is 700r/min.
The urea sulphate was found to have a viscosity of 1752 mPas at 20℃and a pH of 6.2.
Example 5: preparation of liquid urea sulfate
Providing sulfuric acid, urea and water, mixing and dissolving the urea and the water, slowly adding the sulfuric acid into a urea water solution for reaction to obtain liquid urea sulfate; wherein the mass fraction of sulfuric acid is 90 ℃, and the molar ratio of urea to sulfuric acid to water is 3.5:1:1, the reaction temperature is 70 ℃, the reaction time is 25min, and the stirring speed is 750r/min.
The urea sulfate was found to have a viscosity of 1306 mPa.s at 20℃and a pH of 6.1.
Example 6: preparation of liquid urea sulfate
Providing sulfuric acid, urea and water, mixing and dissolving the urea and the water, slowly adding the sulfuric acid into a urea water solution for reaction to obtain liquid urea sulfate; wherein the mass fraction of sulfuric acid is 98 ℃, and the molar ratio of urea to sulfuric acid to water is 1.5:1:1, the reaction temperature is 60 ℃, the reaction time is 20min, and the stirring speed is 720r/min.
The urea sulfate was found to have a viscosity of 1824 mPas at 20℃and a pH of 6.2.
Example 7: preparation of composite fertilizer
Providing potassium chloride, the composite material I prepared in the example 1 and the liquid urea sulfate prepared in the example 4, adding the potassium chloride into the composite material I, mixing at 58 ℃, and crushing to obtain a composite material II; spraying liquid urea sulfate into the composite material II, mixing and granulating in a granulator, wherein the granulating temperature is 72 ℃, the granulating humidity is 30%, the granulating time is 10min, and the granulating temperature is 65 ℃ and the drying is carried out to obtain the compound fertilizer.
Example 8: preparation of composite fertilizer
Providing potassium chloride, the composite material I prepared in the example 2 and the liquid urea sulfate prepared in the example 5, adding the potassium chloride into the composite material I, mixing at 53 ℃, and crushing to obtain a composite material II; spraying liquid urea sulfate into the second composite material, mixing and granulating in a granulator, wherein the granulating temperature is 70 ℃, the granulating humidity is 28%, the granulating time is 8min, and drying is carried out at 65 ℃ to obtain the compound fertilizer.
Example 9: preparation of composite fertilizer
Providing potassium chloride, the composite material I prepared in the example 3 and the liquid urea sulfate prepared in the example 6, adding the potassium chloride into the composite material I, mixing at 60 ℃, and crushing to obtain a composite material II; spraying liquid urea sulfate into the second composite material, mixing and granulating in a granulator, wherein the granulating temperature is 75 ℃, the granulating humidity is 30%, the granulating time is 12min, and the granulating time is 65 ℃ and the compound fertilizer is obtained.
In examples 7-9, the compound fertilizer was made of a compound material I, potassium chloride and liquid urea sulfate, the mass of the compound material I was 600-700kg, the mass of the potassium chloride was 270-350kg, and the mass of the liquid urea sulfate was 30-50kg, based on 1000 kg.
Examples 7-9 the compositions of the raw materials are shown in the following table:
Figure BDA0003915807920000101
comparative example 1: preparation of composite one
Providing ground phosphate rock, sulfuric acid and urea; taking ground phosphate rock, adding sulfuric acid with the mass fraction of 95%, grinding at the pressure of 18MPa and the grinding rotating speed of 150r/min for 20min; adding urea to obtain a first composite material; wherein, the mass ratio of the ground phosphate rock to the sulfuric acid to the urea is 100:90:25.
the effective phosphorus content in composite one was measured to be 9.82% and the phosphorus conversion 79.25%.
Comparative example 2: preparation of liquid urea sulfate
In the presence of zeolite powder, solid urea and 95 mass percent sulfuric acid are mixed according to the molar ratio of urea to sulfuric acid of 2:1 mixing to obtain liquid urea sulfate, wherein the amount of zeolite powder is 1% by weight of the total weight of the liquid urea sulfate; the reaction temperature was 65℃and the reaction time was 23min, with stirring speed of 150r/min.
The urea sulfate was found to have a viscosity of 5427 mPas at 20℃and a pH of 6.0.
Comparative example 3: this comparative example differs from example 7 in that: liquid urea sulfate was prepared by the method of comparative example 2, with the remainder of the procedure being the same as in example 7.
Comparative example 4: this comparative example differs from example 8 in that: composite one was prepared using comparative example 1 and liquid urea sulfate was prepared using comparative example 2, the remainder of the procedure being the same as in example 8.
Comparative example 5: preparation of composite fertilizer
Providing ground phosphate rock, potassium chloride and liquid urea sulfate prepared in example 4, adding the ground phosphate rock into the liquid urea sulfate, reacting for 15min at 80 ℃, then adding weathered coal as a physical property regulator, entering a formation chamber for solidification for 30min, finally adding potassium chloride, mixing, granulating and drying to obtain the product.
In the comparative example, the addition mass of the phosphate rock powder, the liquid urea sulfate and the potassium chloride is the same as that of the example 7, the addition mass of the weathered coal is 5% of the total weight of the compound fertilizer, and other technological parameters are the same as that of the example 7.
The indexes of the compound fertilizers prepared in examples 7 to 9 and comparative examples 3 to 5 were evaluated as follows.
1. With reference to the industry standard HG/T5516-2019, the relative indexes of the compound fertilizers prepared in examples 7-9 and comparative examples 3-5 were measured, and the results are shown in the following table:
Figure BDA0003915807920000121
the results show that the total nutrient (N+P) in the compound fertilizers prepared in examples 7 to 9 of the present invention 2 O 5 +K 2 The mass fraction of O) is more than or equal to 30%, the percentage of water-soluble phosphorus occupied by available phosphorus is more than or equal to 70%, the mass fraction of sulfur (S) is more than or equal to 13%, the percentage of ammonia volatile nitrogen occupied by total nitrogen is less than 15%, the percentage of amide nitrogen occupied by total nitrogen is more than or equal to 70%, and the comprehensive quality is excellent.
The sulfur content, ammonia volatile nitrogen and amide nitrogen of the compound fertilizer prepared in comparative example 3 are reduced compared with those in example 7; the indexes of the compound fertilizer prepared in the comparative example 4 are obviously degraded compared with the indexes of the compound fertilizer prepared in the example 8, which shows that the treatment of the phosphate rock powder in the compound fertilizer and/or the preparation of the liquid urea sulfate can influence the related indexes of the product. The comparative example 5 adopts different process steps to prepare the compound fertilizer, and the obtained compound fertilizer has obvious change of water-soluble phosphorus, sulfur content and amide nitrogen content in total nitrogen, which indicates that the process change can lead the comprehensive index of the product to change unexpectedly under the condition of basically the same raw materials.
2. The compound fertilizers prepared in examples 7-9 and comparative examples 3-5 were tested for particle strength and granulation rate, wherein:
2.1 determination of particle strength: the product particles were laid flat in a screen and divided into four quadrants according to the center point, 25 particles were randomly taken from each quadrant for a total of 100 particles. The particle strength of the whole product is measured by the average particle strength of the 100 products, the average particle strength is measured by the particle strength measuring instrument, and the average particle strength is calculated by the following formula:
Figure BDA0003915807920000122
wherein: average particle strength, N, of M-100 products; particle strength of the X-i product, j=1, 2.
2.2 determination of the granulation rate: screening was performed using standard sieves with pore diameters of 1mm and 4.75 mm. The specific operation steps are as follows: sequentially stacking sieves with the aperture of 1mm and 4.75mm, placing the granulated product in a sieve with the aperture of 4.75mm, manually oscillating to enable the particles to pass through the sieve holes, finally removing all the particles clamped in the sieve holes, and weighing the total weight of the particles in the sieve with the aperture of 1 mm. The granulation rate can be calculated as follows:
Figure BDA0003915807920000131
wherein m is 1 For the total mass of the particles in the 1mm sieve, m 2 Is the total mass of the materials used for granulation.
2.3 test results:
Figure BDA0003915807920000132
the result shows that the grain strength of the compound fertilizer obtained by the granulating method is basically above 40N, and the granulating rate is as high as above 90%; the compound fertilizers prepared by adopting the comparative examples 3, 4 and 5 show different degrees of reduction of the granule strength and the granulation rate, which shows that the used raw materials and the preparation steps thereof have important influence on the granulation effect of the products.
Finally, it is noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present invention, and that other modifications and equivalents thereof by those skilled in the art should be included in the scope of the claims of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. The granulation method for preparing the compound fertilizer by chelating urea sulfate is characterized by comprising the following steps of: the method comprises the following steps:
s01, mixing and grinding ground phosphate rock powder and sulfuric acid, and adding urea to obtain a composite material I;
s02, adding potassium chloride into the composite material I, mixing, and crushing to obtain a composite material II;
s03, mixing and granulating the liquid urea sulfate and the composite material II, and drying to obtain the product.
2. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 1, wherein: in the step S01, the mass fraction of the sulfuric acid is 72-80%, and the grinding time is 18-25min.
3. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 1, wherein: in the S01, the weight ratio of the phosphate rock powder to the sulfuric acid to the urea is 100: (86-92): (7-30).
4. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 1, wherein: in S02, the temperature is below 60 ℃, preferably 50-60 ℃;
the humidity is controlled below 30%.
5. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 1, wherein: the viscosity of the urea sulfate at 20 ℃ is 1000-2000 mPa.s, and the pH is 6.0-6.3.
6. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 5, wherein: the urea sulfate is prepared from urea, sulfuric acid and water, wherein the molar ratio of the urea to the sulfuric acid to the water is (1.5-3.5): 1:1.
7. the granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 6, wherein: the preparation method of the urea sulfate comprises the following steps: mixing urea with water for dissolution, and slowly adding sulfuric acid into urea aqueous solution for reaction to obtain liquid urea sulfate;
preferably, in the preparation method of the urea sulfate, the reaction temperature is 60-70 ℃, the reaction time is 20-25min, the stirring speed is 700-750r/min, and the mass fraction of sulfuric acid is 90-98 ℃.
8. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 1, wherein: in S03, the granulating temperature is 65-75 ℃.
9. The granulation method for producing a compound fertilizer by chelating urea sulfate according to claim 1, wherein: further comprises: and adding medium and trace elements into the composite material II.
10. Compound fertilizer prepared by the granulation process according to any one of claims 1-9.
CN202211339233.5A 2022-10-28 2022-10-28 Granulation method for preparing compound fertilizer by chelating urea sulfate Pending CN116178076A (en)

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