Production method for removing organic toxic substances and improving quality of compound fertilizer

Abstract

The application discloses a production method for removing organic toxic substances and improving the quality of compound fertilizer, and relates to the technical field of compound fertilizer production, and comprises the following steps: step S1, acidolysis-pre-carbonization reaction; step S2, high-temperature oxidation reaction of a tubular reactor; step S3, ammoniation neutralization and by-product recovery; and step S4, granulation forming. The method can efficiently remove organic toxic substances such as "lipid harm" in ammonium dihydrogen phosphate; the appearance and structure of the product are optimized, the L value and the crystal feeling are improved, and the compressive strength of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of compound fertilizer production technology, and in particular to a production method for removing organic toxic substances and improving the quality of compound fertilizer. Background Technology

[0002] With the deepening of the concepts of sustainable agricultural development and green ecological agriculture, the purity and environmental friendliness of fertilizer products are receiving increasing attention. As a key input in agricultural production, the quality of compound fertilizers not only affects crop yield but also directly relates to soil health and ecological environment safety. In the traditional compound fertilizer production process, nitrogen sources (such as urea and ammonium nitrate phosphate) and potassium sources (such as potassium sulfate and potassium chloride) are usually obtained through chemical synthesis or mineral purification, resulting in low impurity content and minimal organic pollution. However, phosphorus sources become the main source of pollution, especially for ammonium dihydrogen phosphate products prepared using the wet-process phosphoric acid technology.

[0003] The current mainstream production of phosphate fertilizer (ammonium dihydrogen phosphate) relies on the wet-process phosphoric acid production method. However, the declining grade of phosphate rock year by year necessitates the use of large quantities of organic flotation reagents such as fatty acids and amines in the flotation process. Simultaneously, as a raw material for producing low-quality ammonium dihydrogen phosphate, the "residual acid" produced during the wet-process phosphoric acid extraction and purification process results in a large amount of organic matter remaining in the ammonium dihydrogen phosphate. This organic residue in ammonium dihydrogen phosphate becomes a major source of pollution for compound fertilizers. These organic substances can cause "lipid damage" to crops, seriously hindering green and ecological agriculture.

[0004] Current research on the removal of organic matter from ammonium dihydrogen phosphate is limited and faces significant technical challenges. On one hand, some organic pollutants are encapsulated within insoluble complex salt crystals, making them difficult to remove effectively through conventional washing or adsorption. On the other hand, traditional thermal treatment methods, relying on external heating, are energy-intensive and costly in continuous industrial production, making them economically unfeasible; while conventional reaction temperatures (such as 70-75℃) are insufficient to induce complete carbonization and decomposition of organic matter. The production methods for high-quality compound fertilizers on the market also suffer from various technical defects, including low organic matter removal rates, reliance on high-purity raw materials, poor adaptability, dull product appearance and weak crystallinity, low compressive strength and easy breakage, high moisture content and easy clumping, and the need for additional fuel for heating to remove organic matter, resulting in low production efficiency.

[0005] Therefore, developing a production method that requires no additional energy consumption, can efficiently remove organic toxic substances from ammonium dihydrogen phosphate, and simultaneously improve the overall quality of compound fertilizer has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to overcome the shortcomings of the prior art and provide a production method for removing organic toxic substances and improving the quality of compound fertilizer. This method can efficiently remove organic toxic substances such as "lipid damage" from ammonium dihydrogen phosphate; optimize the product appearance and structure, improve the L value and crystallinity; increase the compressive strength of the product, reduce the moisture content, and avoid clumping; adapt to various phosphorus source raw materials, reducing dependence on the purity of raw materials; and achieve energy saving in the process by utilizing the heat of reaction, without the need for additional fuel consumption.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A production method for removing organic toxic substances and improving the quality of compound fertilizer includes the following steps:

[0009] Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid and ammonium dihydrogen phosphate are mixed and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry.

[0010] Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas;

[0011] Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S2 and a small amount of acidic gas are introduced into the tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances in the slurry undergo a rapid oxidation reaction with nitrate ions, and the organic toxic substances are completely removed.

[0012] Step S4, Ammoniation Neutralization and By-product Recovery: Maintain a certain pressure in the tubular reactor and introduce excess synthetic ammonia into the mixed slurry to control the slurry neutralization degree at 1.5±0.1 and the water content at 15%±1%; the nitrogen oxides and sulfur dioxide produced by the side reaction in the tubular reactor react rapidly with synthetic ammonia to generate nitrates, nitrites and ammonium sulfate, etc., and these products remain in the slurry as nutrients;

[0013] Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

[0014] Preferably, the molar ratio of concentrated sulfuric acid and industrial-grade ammonium dihydrogen phosphate in step S1 is 1:(0.5-3).

[0015] Preferably, the specific temperature mentioned in step S1 is 70-75℃.

[0016] Preferably, the time specified in step S1 is 5-10 minutes.

[0017] Preferably, the molar ratio of N to P in the acidic slurry in step S1 is 0-0.3 (the calculation principle for the N to P molar ratio in tubular reactor processes is: first subtract the ammonium ions that combine with sulfate, then the molar ratio of the remaining ammonium ions to phosphate ions), and the water content is 3-5%.

[0018] Preferably, the mass ratio of the acidic slurry to the ammonium nitrate phosphate solution in step S2 is 9:(0.1-0.2).

[0019] Preferably, the concentration of the ammonium nitrate phosphorus solution in step S2 is 85% and the specific gravity is 1.4.

[0020] Preferably, the pressure mentioned in step S4 is 8-10 kgf / cm².

[0021] The beneficial effects of adopting the above technical solution are as follows:

[0022] (1) The production method for removing organic toxic substances and improving the quality of compound fertilizer provided by this invention breaks the industry's inherent perception that "impurity removal inevitably consumes energy" and achieves a synergistic breakthrough in energy saving and efficient pest control. When removing organic substances encapsulated in non-water-soluble double salts from ammonium dihydrogen phosphate, existing technologies either rely on high-purity raw materials to avoid impurity problems or require additional fuel consumption for high-temperature treatment, and the treatment efficiency is unstable. However, this invention uses the exothermic reaction of concentrated sulfuric acid and ammonium dihydrogen phosphate (70-75℃ pre-carbonization) combined with the structural design of a tubular reactor to raise the slurry temperature to above 180℃ without additional heating. This not only achieves a steady increase in the removal rate of organic substances but also simultaneously reduces the drying load, completely solving the pain points of "high energy consumption for impurity removal and strong dependence on raw materials" in traditional processes. Its dual improvement in energy saving and pest control efficiency far exceeds the industry's conventional expectations.

[0023] (2) The production method for removing organic toxic substances and improving the quality of compound fertilizer provided by the present invention breaks through the limitation that a single process can only solve a single production quality defect, and realizes multi-dimensional synergistic optimization of "pesticide removal-appearance-strength-stability". Existing technologies, if targeting the removal of organic matter, can often only improve the "lipid damage" problem, and it is difficult to take into account the product's appearance, mechanical properties and anti-caking properties. For example, although some impurity removal processes can reduce the organic matter content, they may cause the product to darken in color or decrease in strength. This application removes organic matter through gradient acid hydrolysis and carbonization, increasing the product's L value from 60-65 (dark) to 82-85 (white). At the same time, the high-temperature slurry promotes the regular growth of crystals, significantly enhancing the product's crystalline appearance. More importantly, the coupled design of the acidic slurry and tubular reactor transforms traditional granules into ammonium phosphate slurry, increasing the product's compressive strength from 25N to 45-55N. The heat of reaction also reduces the moisture content from 1.5-1.8% to 0.5-0.8%, solving the three major quality problems of appearance, strength, and agglomeration in one fell swoop. This multi-dimensional simultaneous improvement in quality is an unexpected effect that is difficult to achieve with existing technologies.

[0024] (3) The production method for removing organic toxic substances and improving the quality of compound fertilizer provided by this invention overturns the traditional logic of "pollution-treatment" of by-products and realizes the resource-based transformation of harmful by-products into fertilizer nutrients. In the existing technology for treating organic matter, nitrogen oxides and sulfur dioxide produced by oxidation reaction are usually regarded as pollutants and require additional equipment for tail gas treatment (such as desulfurization and denitrification), which increases production costs and environmental pressure. However, this technology uses the pressure environment of 8-10 kgf / cm² in a tubular reactor to allow nitrogen oxides and sulfur dioxide to react rapidly with excess synthetic ammonia to generate nutrients such as ammonium nitrate, ammonium nitrite, and ammonium sulfate. These by-products directly enter the granulation system and become part of the compound fertilizer, which not only avoids tail gas pollution but also increases the nitrogen and sulfur nutrient content of the fertilizer, realizing the reverse transformation of "pollutants → nutrients". This dual benefit of environmental protection and added value is a technological breakthrough that was not foreseen in the existing process.

[0025] (4) The production method for removing organic toxic substances and improving the quality of compound fertilizer provided by this invention overcomes the technical bottleneck of "difficult-to-dissociate encapsulation" of non-water-soluble ammonium dihydrogen phosphate double salt, and achieves efficient purification and utilization of low-content "phosphorus source". Existing technologies cannot effectively decompose non-water-soluble ammonium dihydrogen phosphate double salts encapsulating organic matter, resulting in extremely low utilization rates of low-content ammonium dihydrogen phosphate. The industry largely relies on high-content phosphorus sources to produce compound fertilizer. This application, through the directional reaction of concentrated sulfuric acid and ammonium dihydrogen phosphate, fully decomposes approximately 20% of the non-water-soluble double salt, exposing the encapsulated organic matter to an acidic environment for pre-reaction. Then, under high temperature and strong acid conditions above 180°C in a tubular reactor, the organic matter undergoes an oxidation-reduction reaction with nitrate ions. The byproducts are neutralized through ammoniation and used as nutrients in the granulation process as a slurry, eliminating the need for washing and handwashing steps involving acidic gases such as nitrogen oxides, thus completely solving the problem of "organic matter encapsulation by double salt". This breakthrough has enabled the removal rate of organic matter from low-quality phosphorus sources to reach an industry-leading level. It has not only expanded the raw material sources for compound fertilizer production, but also reduced the dependence on high-grade phosphate rock resources. Its ability to "upgrade and utilize" low-quality raw materials far exceeds the application boundaries of existing technologies. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention and to make the above-mentioned features, objectives, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0027] Example 1

[0028] A production method for removing organic toxic substances and improving the quality of compound fertilizer includes the following steps:

[0029] Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid is mixed with industrial grade ammonium dihydrogen phosphate and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the industrial grade ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry.

[0030] Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas;

[0031] Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S2 and a small amount of acidic gas are introduced into the tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances and "fatty" substances in the slurry undergo a rapid oxidation reaction with nitrate ions, completely removing organic toxic substances.

[0032] Step S4, Ammoniation Neutralization and By-product Recovery: Maintain a certain pressure in the tubular reactor and introduce excess synthetic ammonia into the mixed slurry to control the slurry neutralization degree at 1.4 and the water content at 14%; the nitrogen oxides and sulfur dioxide produced by the side reaction in the tubular reactor react rapidly with synthetic ammonia to generate nitrates, nitrites and ammonium sulfates. These products remain in the slurry as nutrients.

[0033] Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

[0034] The molar ratio of concentrated sulfuric acid to ammonium dihydrogen phosphate in step S1 is 1:0.5; the specific temperature in step S1 is 70℃; the specific time in step S1 is 5 minutes; the molar ratio of N to P in the acidic slurry in step S1 is 0, and the water content is 3-5%.

[0035] In step S2, the mass ratio of acidic slurry to ammonium nitrate phosphate solution is 9:0.1; the concentration percentage of ammonium nitrate phosphate solution in step S2 is 85%, and the specific gravity is 1.4; the pressure in step S4 is 8 kgf / cm².

[0036] Example 2

[0037] A production method for removing organic toxic substances and improving the quality of compound fertilizer includes the following steps:

[0038] Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid is mixed with industrial grade ammonium dihydrogen phosphate and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the industrial grade ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry.

[0039] Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas;

[0040] Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S2 is mixed with a small amount of acidic gas in a tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances and "fatty" substances in the slurry undergo a rapid oxidation reaction with nitrate ions, completely removing organic toxic substances.

[0041] Step S4, Ammoniation Neutralization and By-product Recovery: Maintain a certain pressure in the tubular reactor and introduce excess synthetic ammonia into the mixed slurry to control the slurry neutralization degree at 1.5 and the water content at 15%; the nitrogen oxides and sulfur dioxide produced by the side reaction in the tubular reactor react rapidly with synthetic ammonia to generate nitrates, nitrites and ammonium sulfates, etc., which remain in the slurry as nutrients;

[0042] Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

[0043] The molar ratio of concentrated sulfuric acid to ammonium dihydrogen phosphate in step S1 is 1:1; the specific temperature in step S1 is 71℃; the specific time in step S1 is 6 minutes; the molar ratio of N to P in the acidic slurry in step S1 is 0, and the water content is 3-5%.

[0044] The mass ratio of acidic slurry to washing liquid in step S2 is 9:0.12; the concentration of ammonium nitrate phosphate solution in step S2 is 85% and the specific gravity is 1.4; the pressure in step S4 is 8.5 kgf / cm².

[0045] Example 3

[0046] A production method for removing organic toxic substances and improving the quality of compound fertilizer includes the following steps:

[0047] Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid is mixed with industrial grade ammonium dihydrogen phosphate and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the industrial grade ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry.

[0048] Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas;

[0049] Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S2 and a small amount of acidic gas are introduced into the tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances in the slurry undergo a rapid oxidation reaction with nitrate ions, and the organic toxic substances are completely removed.

[0050] Step S4, Ammoniation Neutralization and Byproduct Recovery: Maintaining a certain pressure within the tubular reactor, excess synthetic ammonia is introduced into the mixed slurry to control the slurry neutralization degree at 1.5 and the water content at 15%. Nitrogen oxides and sulfur dioxide produced by the side reactions within the tubular reactor react rapidly with the synthetic ammonia to generate nitrates, nitrites, and ammonium sulfate, etc. These products remain in the slurry as nutrients.

[0051] Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

[0052] The molar ratio of concentrated sulfuric acid to ammonium dihydrogen phosphate in step S1 is 1:2; the specific temperature in step S1 is 75℃; the specific time in step S1 is 8 minutes; the molar ratio of N to P in the acidic slurry in step S1 is 0, and the water content is 3-5%.

[0053] The mass ratio of acidic slurry to ammonium nitrate phosphate solution in step S2 is 9:0.15; the concentration of ammonium nitrate phosphate solution in step S2 is 85% and the specific gravity is 1.4; the pressure in step S4 is 9 kgf / cm².

[0054] Example 4

[0055] A production method for removing organic toxic substances and improving the quality of compound fertilizer includes the following steps:

[0056] Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid is mixed with industrial grade ammonium dihydrogen phosphate and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the industrial grade ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry.

[0057] Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas;

[0058] Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S1 and a small amount of acidic gas are introduced into the tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances in the slurry undergo a rapid oxidation reaction with nitrate ions, and the organic toxic substances are completely removed.

[0059] Step S4, Ammoniation Neutralization and Byproduct Recovery: Maintaining a certain pressure within the tubular reactor, excess synthetic ammonia is introduced into the mixed slurry to control the slurry neutralization degree at 1.6 and the water content at 16%. Nitrogen oxides and sulfur dioxide produced by the side reactions within the tubular reactor react rapidly with the synthetic ammonia to generate nitrates, nitrites, and ammonium sulfates. These products remain in the slurry as nutrients.

[0060] Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

[0061] The molar ratio of concentrated sulfuric acid to ammonium dihydrogen phosphate in step S1 is 1:2.5; the specific temperature in step S1 is 74℃; the specific time in step S1 is 9 min; the molar ratio of N to P in the acidic slurry in step S1 is 0.2, and the water content is 3-5%.

[0062] The mass ratio of the acidic slurry to the ammonium nitrate phosphate solution in step S2 is 9:0.18; the concentration of the ammonium nitrate phosphate solution in step S2 is 85%, and the specific gravity is 1.4; the pressure in step S4 is 9.5 kgf / cm².

[0063] Example 5

[0064] A production method for removing organic toxic substances and improving the quality of compound fertilizer includes the following steps:

[0065] Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid is mixed with industrial grade ammonium dihydrogen phosphate and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the industrial grade ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry.

[0066] Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas;

[0067] Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S2 and a small amount of acidic gas are introduced into the tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances in the slurry undergo a rapid oxidation reaction with nitrate ions, and the organic toxic substances are completely removed.

[0068] Step S4, Ammoniation Neutralization and Byproduct Recovery: Maintaining a certain pressure within the tubular reactor, excess synthetic ammonia is introduced into the mixed slurry to control the slurry neutralization degree at 1.6 and the water content at 16%. Nitrogen oxides and sulfur dioxide produced by the side reactions within the tubular reactor react rapidly with the synthetic ammonia to generate nitrates, nitrites, and ammonium sulfates, etc. These products remain in the slurry as nutrients.

[0069] Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

[0070] The molar ratio of concentrated sulfuric acid to ammonium dihydrogen phosphate in step S1 is 1:3; the specific temperature in step S1 is 73℃; the specific time in step S1 is 10 min; the molar ratio of N to P in the acidic slurry in step S1 is 0.33, and the water content is 3-5%.

[0071] The mass ratio of the acidic slurry to the ammonium nitrate phosphate solution in step S2 is 9:0.2; the concentration of the ammonium nitrate phosphate solution in step S2 is 85%, and the specific gravity is 1.4; the pressure in step S3 is 10 kgf / cm².

[0072] Comparative Example 1

[0073] This example provides a production method for removing organic toxic substances and improving the quality of compound fertilizer, which is basically the same as Example 1, except that there is no acid hydrolysis-pre-carbonization reaction step.

[0074] Comparative Example 2

[0075] This example provides a production method for removing organic toxic substances and improving the quality of compound fertilizer, which is basically the same as Example 1, except that there is no high-temperature oxidation reaction step in a tubular reactor.

[0076] Using low-content ammonium dihydrogen phosphate (organic content 0.028%) of model 11-44-0 as raw material, compound fertilizer was produced using the methods described above. Relevant performance tests were conducted using current Chinese national standards or conventional methods in this field. The test results are shown in Table 1.

[0077] As can be seen from Table 1, the production method for removing organic toxic substances and improving the quality of compound fertilizer disclosed in the embodiments of the present invention has better organic matter removal effect, appearance and strength compared with the comparative example. The combination of acid hydrolysis-precarbonization reaction step and high-temperature oxidation reaction step in tubular reactor has a positive promoting effect on improving the above performance.

[0078] Table 1

[0079]

[0080] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A production method for removing organic toxic substances and improving the quality of compound fertilizer, characterized in that, Includes the following steps: Step S1, acid hydrolysis-pre-carbonization reaction: concentrated sulfuric acid and ammonium dihydrogen phosphate are mixed and heated, and reacted at a certain temperature for a certain time, so that some of the non-water-soluble ammonium dihydrogen phosphate double salt in the ammonium dihydrogen phosphate is fully desorbed, and the organic matter encapsulated therein is dissociated into the acidic environment and partially carbonized, resulting in an acidic slurry. Step S2, mixing acidic slurry with ammonium nitrate phosphorus solution - pre-oxidation reaction: ammonium nitrate phosphorus solution is added to the outlet of the S1 acidic slurry pump, mixed thoroughly and undergoes partial oxidation reaction to obtain acidic slurry and a small amount of acidic gas; Step S3, High-temperature oxidation reaction in tubular reactor: The acidic slurry obtained in step S2 and a small amount of acidic gas are introduced into the tubular reactor; by utilizing the reaction heat of the acidolysis reaction and the structural design of the tubular reactor, the temperature of the mixed slurry is raised to above 180°C. Under the high-temperature acidic environment, the carbonized substances and "fatty" substances in the slurry undergo a rapid oxidation reaction with nitrate ions, and the organic toxic substances are completely removed. Step S4, Ammoniation Neutralization and By-product Recovery: Maintain a certain pressure in the tubular reactor and introduce excess synthetic ammonia into the mixed slurry to control the slurry neutralization degree at 1.5±0.1 and the water content at 15%±1%; the nitrogen oxides and sulfur dioxide produced by the side reaction in the tubular reactor react rapidly with synthetic ammonia to generate salts such as nitrates, nitrites and ammonium sulfate. These products remain in the slurry as nutrients. Step S5, Granulation and Molding: The slurry containing nutrient salts obtained in step S4 is fed into the granulation system and granulated to obtain the compound fertilizer product.

2. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The molar ratio of concentrated sulfuric acid and ammonium dihydrogen phosphate in step S1 is 1:(0.5-3).

3. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The specific temperature mentioned in step S1 is 70-75℃.

4. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The specified time in step S1 is 5-10 minutes.

5. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The acidic slurry in step S1 has a N to P molar ratio of 0-0.3 and a water content of 3-5%.

6. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The mass ratio of the acidic slurry to the ammonium nitrate phosphate solution in step S2 is 9:(0.1-0.2).

7. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The concentration of the ammonium nitrate phosphate solution in step S2 is 85%, and the specific gravity is 1.

4.

8. The production method for removing organic toxic substances and improving the quality of compound fertilizer according to claim 1, characterized in that, The pressure mentioned in step S3 is 8-10 kgf / cm².

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