Zinc-containing diammonium phosphate, preparation method thereof and fertilizer containing zinc-containing diammonium phosphate

Abstract

The invention belongs to the technical field of phosphate fertilizer production, and particularly relates to zinc-containing diammonium phosphate, a preparation method thereof and a fertilizer containing the zinc-containing diammonium phosphate. The zinc-containing diammonium phosphate is prepared by wrapping the outer layer of a solid zinc fertilizer with elemental sulfur to obtain sulfur-zinc-containing mixed slurry, and spraying the sulfur-zinc-containing mixed slurry onto diammonium phosphate for granulation, thereby obtaining the zinc-containing diammonium phosphate. Wherein the addition amount of the solid zinc fertilizer accounts for 30-100% of the total mass of the elemental sulfur; based on the total weight of the zinc-containing diammonium phosphate, the addition amount of the sulfur-zinc-containing mixed slurry is 1-10%. According to the preparation method, direct contact and antagonistic reaction of phosphate radicals and zinc ions are avoided, degradation of phosphorus and zinc nutrients is avoided, and a relatively good water-soluble zinc content ratio and a relatively good water-soluble phosphorus content ratio are kept.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphate fertilizer production, and in particular relates to zinc-containing diammonium phosphate and a preparation method thereof, including a fertilizer containing zinc-containing diammonium phosphate. Technical Background

[0002] The area of ​​zinc deficiency in my country's soil accounts for more than 50% of the total cultivated land area. Zinc deficiency has become one of the important factors restricting the increase in crop yield and quality in my country, especially in the calcareous soil in the north. Diammonium phosphate is the main phosphate fertilizer product in my country and the most commonly used by farmers. In order to supplement zinc nutrition and upgrade traditional phosphate fertilizer products, the addition of zinc to diammonium phosphate has become a common choice in the industry. Patents CN106431563A and CN110590479A report the method of adding zinc fertilizer to the granulator by adding solid zinc oxide to the return hopper lifter. Patent CN101723733B reports that zinc oxide is metered and added to the ditch, and then the washing liquid is flushed into the underground tank to form a mixed liquid, and then the mixed liquid is pumped into the pre-neutralization tank and the tubular reaction feed tank to obtain zinc diammonium phosphate slurry, and finally the zinc ammonium phosphate slurry is pumped into the granulator for spraying granulation. The zinc fertilizer addition method. Patent CN103787723A reports the method of adding zinc sulfate to the pre-neutralizer for granulation. Patent CN101967070A reports a method for adding tailings slurry containing zinc, manganese and boron to a fast ammonia reactor and then granulating to produce ammonium phosphate compound fertilizer containing sulfur, zinc, manganese and boron. However, a large number of studies at home and abroad have shown that the size of the agronomic effect of zinc fertilizer is linearly related to the water solubility of zinc fertilizer. The higher the proportion of water-soluble zinc content, the better the agronomic benefit. In the report of the above patent, whether the zinc fertilizer is directly added to the granulator, flushed into the underground tank by washing liquid, added to the pre-neutralizer, or the zinc-containing tailings are added to the fast ammonia reactor, the zinc fertilizer is directly in contact with the phosphate ions in the phosphate fertilizer or phosphoric acid to generate zinc phosphate, zinc ammonium phosphate and other difficult (slightly) soluble substances; At the same time, it will also reduce the proportion of water-soluble content of phosphorus to a certain extent. Adding chelated zinc can effectively avoid the precipitation reaction of phosphorus and zinc, but the price of chelated zinc fertilizer is much higher than that of ordinary zinc fertilizer. When the amount added is slightly increased, the investment cost of fertilizer manufacturers and consumers will be greatly increased. In addition, amino acid chelated zinc is also added to fertilizers. However, during the granulation process, especially the temperature in the front section of the dryer is relatively high, which can easily lead to the decomposition and carbonization of amino acids and the loss of their original properties. Therefore, adding chelated zinc to fertilizers is not the best choice. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing zinc-containing diammonium phosphate in view of the shortcomings of existing zinc fertilizer addition technology for diammonium phosphate products and the high cost caused by adding chelated zinc, thereby solving the problems of low proportion of water-soluble zinc content, low agronomic effect and high cost of adding chelated zinc caused by adding ordinary zinc fertilizer to diammonium phosphate products.

[0004] The purpose of the present invention is achieved through the following technical solutions.

[0005] Unless otherwise specified, all percentages used in the present invention are by mass.

[0006] The invention provides a method for preparing zinc-containing diammonium phosphate, which comprises the steps of wrapping elemental sulfur on the outer layer of solid zinc fertilizer to obtain a sulfur-containing zinc mixed slurry, and then spraying the sulfur-containing zinc mixed slurry onto diammonium phosphate for granulation to obtain the zinc-containing diammonium phosphate.

[0007] As a preferred embodiment of the present invention, the added amount of the solid zinc fertilizer accounts for 30-100% of the total mass of the elemental sulfur.

[0008] As a preferred embodiment of the present invention, the addition amount of the sulfur-zinc mixed slurry is 1-10% based on the total weight of the zinc-containing diammonium phosphate.

[0009] As a preferred embodiment of the present invention, the elemental sulfur is sulfur. Modified sulfur in the prior art can also be selected, such as micro-powdered sulfur with a smaller particle size, bio-sulfur, etc.

[0010] As a preferred embodiment of the present invention, encapsulating elemental sulfur is to mix solid zinc fertilizer with liquid elemental sulfur and then stir the mixture at 130-150° C. for 0.5-1 hour.

[0011] As a preferred embodiment of the present invention, the solid zinc fertilizer is zinc sulfate monohydrate, anhydrous zinc sulfate or zinc oxide.

[0012] More preferably, the solid zinc fertilizer is zinc sulfate monohydrate.

[0013] As a preferred embodiment of the present invention, the particle size of the solid zinc fertilizer is 1nm to 0.25mm.

[0014] The present invention also provides zinc-containing diammonium phosphate prepared according to the above method, wherein the zinc-containing diammonium phosphate is composed of elemental sulfur, zinc fertilizer and diammonium phosphate, the elemental sulfur is wrapped around the zinc fertilizer to form zinc-sulfur fertilizer particles, and the zinc-sulfur fertilizer particles are filled in the gaps between the diammonium phosphate particles; wherein the addition amount of the zinc fertilizer accounts for 30-100% of the total mass of the elemental sulfur; and the addition amount of the sulfur-zinc mixed slurry is 1-10% based on the total weight of the zinc-containing diammonium phosphate.

[0015] The invention also provides a fertilizer, which comprises the zinc-containing diammonium phosphate.

[0016] Compared with existing products and technologies, the present invention has the following advantages:

[0017] 1. The present invention adds zinc fertilizer into a liquid sulfur tank, wraps a layer of elemental sulfur on the outside of the zinc fertilizer, and then directly sprays it into a granulator for granulation through an air compressor pump. Because there is a layer of elemental sulfur between phosphorus and zinc, direct contact and antagonistic reaction between phosphate and zinc ions are avoided, thereby avoiding the degradation of phosphorus and zinc nutrients, and maintaining a good proportion of water-soluble zinc content and water-soluble phosphorus content.

[0018] 2. The amount of zinc fertilizer that can be selected in the present invention is 30-100% of the amount of sulfur added; the particle size of the zinc fertilizer is 1nm-0.25mm, which can be well wrapped and evenly coated by liquid sulfur. The amount of sulfur-containing zinc slurry in the liquid sulfur tank sprayed into the granulator is 1-10% of the total amount of zinc-containing diammonium phosphate. At this time, the zinc-containing diammonium phosphate contains 0.5-5% elemental S and 0.1-1.5% Zn, which can better meet the needs of crops for sulfur and zinc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a schematic diagram of the process flow of adding zinc fertilizer according to the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the product of the present invention, 1. elemental sulfur; 2. zinc fertilizer; 3. ammonium phosphate.

[0021] Figure 3 is the X-ray diffraction analysis of the zinc diammonium phosphate sample prepared in Example 1; DAP+ZnSO 4 +S fusion, zinc diammonium phosphate sample prepared in Example 1; DAP+ZnSO 4 +S Mixture: a zinc-containing diammonium phosphate sample prepared by a conventional method, wherein the mixing ratio of zinc fertilizer to diammonium phosphate is the same as that in Example 1; (NH 4 ) 2 HPO 4 , PDF#97-000-2799 and Zn 3 (PO 4 ) 2 PDF#00-030-1490(RDB) are all standard materials.

[0022] Figure 4 The X-ray diffraction analysis of the zinc-containing diammonium phosphate sample prepared in Example 2; DAP+ZnO+S fusion (Fusion), the zinc-containing diammonium phosphate sample prepared in Example 2; DAP+ZnO+S mixing (Mixture), the zinc-containing diammonium phosphate sample prepared by the traditional method, the mixing ratio of zinc fertilizer and diammonium phosphate is the same as in Example 2; (NH 4 ) 2 HPO 4 , PDF#97-000-2799 and Zn 3 (PO 4 )2 PDF#00-030-1490(RDB) are all standard materials.

[0023] Figures 5 to 9 It is the dry matter weight and nutrient content of Chinese cabbage in Example 4.

[0024] Figures 10 to 14 It is the dry matter weight and nutrient content of Chinese cabbage in Example 5. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0026] Diammonium phosphate is the main phosphate fertilizer product in my country and the most commonly used by farmers. In order to supplement zinc nutrition and upgrade traditional phosphate fertilizer products, the addition of zinc to diammonium phosphate has become a common choice in the industry. However, the existing addition methods have the following technical problems: zinc fertilizers are in direct contact with phosphate ions in phosphate fertilizers or phosphoric acid to generate insoluble (slightly) soluble substances such as zinc phosphate and zinc ammonium phosphate; at the same time, the proportion of water-soluble phosphorus will be reduced to a certain extent. Adding chelated zinc can effectively avoid the precipitation reaction of phosphorus and zinc, but the price of chelated zinc fertilizer is much higher than that of ordinary zinc fertilizer. When the amount added is slightly increased, the input cost of fertilizer manufacturers and consumers will be greatly increased; in addition, amino acid chelated zinc is also added to fertilizers, but during the granulation process, especially the temperature in the front section of the dryer is high, which can easily lead to amino acid decomposition and carbonization, and lose its original performance; therefore, adding chelated zinc to fertilizers is not the best choice.

[0027] The invention provides a method for preparing zinc-containing diammonium phosphate, which comprises the steps of wrapping elemental sulfur on the outer layer of solid zinc fertilizer to obtain a sulfur-containing zinc mixed slurry, and then spraying the sulfur-containing zinc mixed slurry onto diammonium phosphate for granulation to obtain the zinc-containing diammonium phosphate.

[0028] The present invention adds zinc fertilizer into a liquid sulfur tank, wraps a layer of elemental sulfur outside the zinc fertilizer, and then directly sprays it into a granulator for granulation through an air compressor pump. Since there is a layer of elemental sulfur between phosphorus and zinc, direct contact and antagonistic reaction between phosphate and zinc ions are avoided, thereby avoiding the degradation of phosphorus and zinc nutrients, and maintaining a good proportion of water-soluble zinc content and water-soluble phosphorus content.

[0029] It should be noted that the zinc-containing diammonium phosphate sample prepared by the traditional method described in the embodiment of the present invention is obtained by directly mixing zinc fertilizer and diammonium phosphate.

[0030] Example 1

[0031] A method for adding zinc fertilizer to a diammonium phosphate product, such as Figure 1 As shown, the following steps are included:

[0032] Diammonium phosphate (15% N, 42% P2 O 5 ), sulfur is passed through a 60-mesh sieve, and zinc sulfate monohydrate (35% Zn) is passed through a 200-mesh sieve for later use. Add an appropriate amount of sulfur into the melting tank to melt the sulfur, and control the temperature of the melting tank at 130°C. Add zinc sulfate monohydrate into the liquid sulfur melting tank at a mass ratio of 1:1 with elemental sulfur. After stirring for 30 minutes, a sulfur-containing zinc slurry is formed. The sulfur-containing zinc slurry is directly sprayed onto the diammonium phosphate material in the disc granulator through an air compressor pump for granulation. The amount of sulfur-containing zinc slurry sprayed is 3% of the total material. Particles smaller than 1 mm or larger than 4 mm are re-crushed and added to the disc granulator for re-granulation. After drying, screening, cooling and packaging, a zinc-containing diammonium phosphate sample is formed. The structural schematic diagram of the zinc-containing diammonium phosphate sample is shown as follows Figure 2 shown.

[0033] Example 2

[0034] A method for adding zinc fertilizer to a diammonium phosphate product, such as Figure 1 As shown, the following steps are included:

[0035] Diammonium phosphate (15% N, 42% P 2 O 5 ), sulfur, zinc oxide (80% Zn) are sieved through a 60-mesh sieve for later use. Add an appropriate amount of sulfur into the melting tank to melt the sulfur, and control the temperature of the melting tank at 130°C. Add zinc sulfate monohydrate into the liquid sulfur melting tank at a mass ratio of 1:3 to elemental sulfur. Stir for 60 minutes to form a sulfur-containing zinc slurry. Spray the sulfur-containing zinc slurry directly onto the diammonium phosphate material in the disc granulator through an air compressor pump for granulation. The amount of sulfur-containing zinc slurry sprayed is 5% of the total material. Particles smaller than 1 mm or larger than 4 mm are re-crushed and added to the disc granulator for re-granulation. After drying, screening, cooling and packaging, a zinc-containing diammonium phosphate sample is formed. The structural schematic diagram of the zinc-containing diammonium phosphate sample is shown in Figure 2 shown.

[0036] Example 3

[0037] A method for adding zinc fertilizer to a diammonium phosphate product, such as Figure 1 As shown, the following steps are included:

[0038] Diammonium phosphate (15% N, 42% P 2 O 5), sulfur is passed through a 60-mesh sieve, and zinc sulfate monohydrate (35% Zn) is passed through a 200-mesh sieve for later use. Add an appropriate amount of sulfur into the melting tank to melt the sulfur, and control the temperature of the melting tank at 150°C. Add zinc sulfate monohydrate into the liquid sulfur melting tank at a mass ratio of 1:1 with elemental sulfur. After stirring for 30 minutes, a sulfur-containing zinc slurry is formed. The sulfur-containing zinc slurry is directly sprayed onto the diammonium phosphate material in the disc granulator through an air compressor pump for granulation. The amount of sulfur-containing zinc slurry sprayed is 10% of the total material. Particles smaller than 1 mm or larger than 4 mm are re-crushed and added to the disc granulator for re-granulation. After drying, screening, cooling and packaging, a zinc-containing diammonium phosphate sample is formed. The structural schematic diagram of the zinc-containing diammonium phosphate sample is shown as follows Figure 2 shown.

[0039] Example 4

[0040] A method for adding zinc fertilizer to a diammonium phosphate product, such as Figure 1 As shown, the following steps are included:

[0041] Diammonium phosphate (15% N, 42% P 2 O 5 ), sulfur is passed through a 60-mesh sieve, and zinc sulfate monohydrate (35% Zn) is passed through a 200-mesh sieve for later use. Add an appropriate amount of sulfur into the melting tank to melt the sulfur, and control the temperature of the melting tank at 150°C. Add zinc sulfate monohydrate into the liquid sulfur melting tank at a mass ratio of 1:2 to elemental sulfur. After stirring for 60 minutes, a sulfur-containing zinc slurry is formed. The sulfur-containing zinc slurry is directly sprayed onto the diammonium phosphate material in the disc granulator through an air compressor pump for granulation. The amount of sulfur-containing zinc slurry sprayed is 1% of the total material. Particles smaller than 1 mm or larger than 4 mm are re-crushed and added to the disc granulator for re-granulation. After drying, screening, cooling and packaging, a zinc-containing diammonium phosphate sample is formed. The structural schematic diagram of the zinc-containing diammonium phosphate sample is shown as follows Figure 2 shown.

[0042] Since Examples 1 to 4 all prepared zinc-containing diammonium phosphate samples with the expected effects of the present invention, the present invention only takes the zinc-containing diammonium phosphate samples prepared in Examples 1 to 2 as examples to illustrate their properties and effects.

[0043] The samples obtained in Example 1 and Example 2 were subjected to X-ray diffraction analysis to analyze their phase changes. Figure 3 It can be seen that when the diffraction angle (2θ) is between 20 and 20.7°, 22.72 and 23.02°, and 28.16 and 28.72°, the relative diffraction intensity of the molten state is significantly reduced compared with the traditional addition method, indicating that the content of zinc phosphate products in the molten state added fertilizer product prepared by the present invention is reduced. Figure 4 It can be seen that there is no obvious change in the physical phase of the fertilizer product added in the molten state and the conventional mixed state.

[0044] Experimental Example 1

[0045] Fertilizer efficiency test

[0046] The test fertilizer was the fertilizer sample prepared in Example 1 (14.4% N, 42.1% P 2 O 5 , 0.90% Zn, 2.70% elemental S), the basic information of the tested soil was: pH 8.27, organic matter 1.10%, total nitrogen content 690 mg kg -1 , the available potassium is 91.3 mg kg -1 , the effective phosphorus content is 11.6 mg kg -1 , effective sulfur 10.97mg / kg, effective zinc content 1.64mgvkg -1 Test crop: Chinese cabbage. This experiment has two treatments; see Table 1 for the specific treatments. The mixing ratio of zinc fertilizer and diammonium phosphate in E2 is the same as that in Example 1.

[0047] Table 1 Fertilization treatments

[0048] Processing number Processing Name Fertilizer amount (g / pot) Fertilization method Example 1 (E1) <![CDATA[Ammonium dihydrogen phosphate + ZnSO 4 (added by melting)]]> 0.88 Apply fertilizer in holes, with a spacing of 4 cm between seeds and fertilizers E2 (prepared by traditional method) <![CDATA[Ammonium dihydrogen phosphate + ZnSO 4 (mixed addition)]]> 0.88 Apply fertilizer in holes, with a spacing of 4 cm between seeds and fertilizers

[0049] Each treatment was repeated 4 times, randomly arranged, and the soil weight of each pot was 3.5kg. Ten Chinese cabbage seeds were spread in each pot, and one Chinese cabbage seedling with good growth and uniform growth was retained. Watering was done regularly to maintain 75% of the field water holding capacity. The fertilizer amount for all treatments was 0.88g / pot, and the fertilizer amount was calculated based on phosphorus, and the remaining nitrogen and potassium were supplemented with ammonium chloride and potassium chloride.

[0050] Depend on Figures 5 to 9 It can be seen that compared with traditional zinc-containing diammonium phosphate, the dry matter weight, nitrogen content, phosphorus content, sulfur content and zinc content of the aboveground part of Chinese cabbage increased by about 40.00%, 4.23%, 11.02%, 20.00% and 18.37%, respectively.

[0051] Experimental Example 2

[0052] Fertilizer efficiency test

[0053] The test fertilizer was the fertilizer sample prepared in Example 2 (14.6% N, 41.8% P 2 O 5 , 0.93% Zn, 2.76% elemental S), the basic information of the tested soil is: pH 8.27, organic matter 1.10%, total nitrogen content 690mgvkg -1 , the available potassium is 91.3 mg kg -1 , the effective phosphorus content is 11.6 mg kg -1 , effective sulfur 10.97mg / kg, effective zinc content 1.64mg·kg -1Test crop: Chinese cabbage. This experiment has two treatments; see Table 2 for the specific treatments. The mixing ratio of zinc fertilizer and diammonium phosphate in E4 is the same as that in Example 2.

[0054] Table 2 Fertilization treatments

[0055] Processing number Processing Name Fertilizer amount (g / pot) Fertilization method Example 2 (E3) Diammonium phosphate + ZnO (molten addition) 0.87 Apply fertilizer in holes, with a spacing of 4 cm between seeds and fertilizers E4 (prepared by traditional method) Diammonium phosphate + ZnO (mixed addition) 0.87 Apply fertilizer in holes, with a spacing of 4 cm between seeds and fertilizers

[0056] Each treatment was repeated 4 times, randomly arranged, and the soil weight of each pot was 3.5 kg. Ten seeds of Chinese cabbage were sown in each pot, and one Chinese cabbage seedling with good growth and uniform growth was retained. Watering was done regularly to maintain 75% of the field water holding capacity. The fertilizer amount for all treatments was 0.87 g / pot, and the fertilizer amount was calculated based on phosphorus. The remaining nitrogen and potassium were supplemented with ammonium chloride and potassium chloride. The dry weight and nutrient content of Chinese cabbage are shown in Figures 10 to 14 shown.

[0057] Compared with the traditional zinc-containing diammonium phosphate addition method, after the zinc-containing diammonium phosphate prepared by the method provided by the present invention is applied, the aboveground dry matter weight, nitrogen content, phosphorus content, sulfur content and zinc content of the second-season Chinese cabbage are increased by about 30.21%, 12.14%, 9.90%, 20.80% and 18.40%, respectively.

[0058] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing zinc-containing diammonium phosphate, characterized in that: The method comprises wrapping elemental sulfur on the outer layer of solid zinc fertilizer to obtain a sulfur-containing zinc mixed slurry, and then spraying the sulfur-containing zinc mixed slurry onto diammonium phosphate for granulation to obtain zinc-containing diammonium phosphate; Wherein, the addition amount of the solid zinc fertilizer accounts for 30-100% of the total mass of the elemental sulfur; The amount of the sulfur-zinc mixed slurry added is 1-10% based on the total weight of the zinc-containing diammonium phosphate.

2. The method for preparing zinc-containing diammonium phosphate according to claim 1, characterized in that: The elemental sulfur is sulfur.

3. The method for preparing zinc-containing diammonium phosphate according to claim 1, characterized in that: Encapsulated elemental sulfur is prepared by mixing solid zinc fertilizer with liquid elemental sulfur and stirring the mixture at 130-150°C for 0.5-1h.

4. The method for preparing zinc-containing diammonium phosphate according to claim 1, characterized in that: The solid zinc fertilizer is zinc sulfate monohydrate, anhydrous zinc sulfate or zinc oxide.

5. The method for preparing zinc-containing diammonium phosphate according to claim 4, characterized in that: The solid zinc fertilizer is zinc sulfate monohydrate.

6. The method for preparing zinc-containing diammonium phosphate according to claim 1, characterized in that: The particle size of the solid zinc fertilizer is 1 nm to 0.25 mm.

7. A zinc-containing diammonium phosphate prepared according to the method according to any one of claims 1 to 6, characterized in that: The zinc-containing diammonium phosphate is composed of elemental sulfur, zinc fertilizer and diammonium phosphate, the elemental sulfur is wrapped around the zinc fertilizer to form zinc-sulfur fertilizer particles, and the zinc-sulfur fertilizer particles are filled in the gaps between the diammonium phosphate particles; wherein the added amount of the zinc fertilizer accounts for 30 to 100% of the total mass of the elemental sulfur; and the added amount of the zinc-sulfur fertilizer particles is 1 to 10% based on the total weight of the zinc-containing diammonium phosphate.

8. A fertilizer, characterized in that It comprises the zinc-containing diammonium phosphate as described in claim 7.

Images