Amide calcium magnesium fertilizer as well as preparation method and application thereof

Abstract

The invention discloses an amide calcium magnesium fertilizer, which is prepared from the following raw materials in parts by weight: 50 to 60.6 parts of calcium magnesium concentrated solution C and 39.4 to 50 parts of urea. The amide calcium magnesium fertilizer contains a nitrogen source, calcium ions and magnesium ions required by plant growth, so that the content of chlorophyll in plants can be increased, and the plant growth can be promoted; the invention also discloses a preparation method and application of the amide calcium-magnesium fertilizer, and the preparation method comprises the following steps: S1, adding lime milk with the solid content of 40% into calcium-magnesium liquid for neutralization to obtain neutralized liquid E; s2, filtering the neutralization solution E to obtain a neutralization filter cake A and a calcium-magnesium neutralization solution B; s3, heating and concentrating the calcium-magnesium neutralization solution B, and converting the calcium-magnesium neutralization solution B from yellow transparent to white to obtain a calcium-magnesium concentrated solution C; and S4, taking 50-60.6 parts of calcium and 39.4-50 parts of urea, uniformly mixing, heating to a molten state at the temperature of 110 DEG C or below, cooling, and granulating to obtain the amide calcium magnesium fertilizer F. The amide calcium magnesium fertilizer is formed by sequentially neutralizing, concentrating and granulating a calcium magnesium liquid byproduct produced in the nitric acid method ore dressing process, so that the utilization rate of the calcium magnesium liquid is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral processing by-products, and in particular to an amide calcium magnesium fertilizer, a preparation method thereof and an application thereof. Background Art

[0002] In phosphate and fertilizer processing enterprises, chemical beneficiation byproducts contain calcium and magnesium ion compounds, which are indispensable elements for agriculture, forestry, and fruit trees, and are beneficial to the growth of agriculture, forestry, and fruit trees;

[0003] Referring to the method for nitric acid method beneficiation and enrichment of phosphate concentrate and co-production of calcium nitrate and magnesium fertilizer disclosed in Chinese patent CN116462533A, calcium and magnesium concentrated solution by-products are produced in the nitric acid method beneficiation process; in the actual production process, the reaction sequence of the previous stage of the calcium and magnesium concentrated solution production link is different, and the output of the calcium and magnesium concentrated solution is faster than the consumption of the calcium and magnesium concentrated solution. If there are fewer storage tanks for temporarily storing the calcium and magnesium concentrated solution, the consumption of the calcium and magnesium concentrated solution cannot keep up with the output, and the beneficiation workshop is forced to stop production, which will cause great economic losses. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides an amide calcium-magnesium fertilizer which can utilize the calcium-magnesium solution in the ore dressing process, a preparation method thereof and application thereof.

[0005] In order to solve the above technical problems, the first solution provided by the present invention is:

[0006] An amide calcium magnesium fertilizer is composed of the following raw materials in parts by weight: 50-60.6 parts of calcium magnesium concentrate C and 39.4-50 parts of urea.

[0007] Urea has a certain viscosity under wet conditions and can be used as a binder between particles to help the particles combine together during the granulation process. When the ratio of urea to calcium magnesium concentrate C meets the above relationship, amide calcium magnesium fertilizer becomes granular.

[0008] The amide calcium magnesium fertilizer as described above, wherein the calcium magnesium concentrated solution C is prepared by adding an alkaline substance to a calcium magnesium solution and then concentrating the solution.

[0009] As described above, the amide calcium magnesium fertilizer contains N 总 >27%.

[0010] The amide calcium magnesium fertilizer as described above contains nitrate nitrogen and amide nitrogen; wherein N 硝 >7%、N 酰胺 >18%.

[0011] The amide calcium magnesium fertilizer as mentioned above contains CaO and MgO; wherein CaO>12% and MgO>2%.

[0012] In order to solve the above technical problems, the second solution provided by the present invention requires raw materials including calcium-magnesium liquid, wherein the calcium-magnesium liquid is obtained by separating medium- and low-grade phosphate ore as raw materials through chemical beneficiation in a nitric acid beneficiation process, and the specific manufacturing process of the calcium-magnesium liquid is as follows: the medium- and low-grade phosphate ore is an ore that has been ground and calcined;

[0013] The ore is ground to obtain fine ore powder, and the ground phosphate ore powder can be directly leached with nitric acid for mineral processing;

[0014] It can also be calcined and then leached with nitric acid for mineral processing. The calcination temperature is 900-1100℃, which decomposes the dolomite and calcite in the phosphate ore. Dolomite is mainly composed of calcium carbonate and magnesium carbonate. Calcite is a calcium carbonate mineral. Calcium carbonate decomposes to generate calcium oxide and releases carbon dioxide gas when heated. Magnesium carbonate decomposes to generate magnesium oxide and releases carbon dioxide gas when heated. The main chemical reactions are:

[0015] CaCO3·MgCO3→CaO+MgO+2CO2↑

[0016] CaCO3→CaO+CO2↑

[0017] C+O2→CO2

[0018] The chemical beneficiation comprises: leaching the medium and low grade phosphate ore with dilute nitric acid, the concentration of the dilute nitric acid is 14-18%, the leaching temperature is 45-50°C, the leaching time is 2.5-3.5h, quicklime or calcium hydroxide is added to the leaching solution to obtain a calcium nitrate magnesium mixed solution with a pH value of 4.0-5.0.

[0019] The ground phosphate rock powder is directly leached with dilute nitric acid for beneficiation. Calcium carbonate reacts with dilute nitric acid to generate calcium nitrate and release carbon dioxide gas. Magnesium carbonate reacts with dilute nitric acid to generate magnesium nitrate and release carbon dioxide gas to obtain calcium-magnesium liquid. The main chemical reactions are:

[0020] CaCO3·MgCO3+4HNO3→Ca(NO3)2+Mg(NO3)2+2H2O+2CO2↑

[0021] CaCO3+2HNO3→Ca(NO3)2+H2O+CO2↑

[0022] Furthermore, the calcium oxide and magnesium oxide in the calcined phosphate rock powder cannot be directly leached out. The water in the dilute nitric acid can digest the calcium oxide and magnesium oxide in the ore to generate calcium hydroxide and magnesium hydroxide. The nitric acid is then used to dissolve and leach the calcium and magnesium elements in the ore to obtain calcium-magnesium liquid. The main chemical reactions are:

[0023] CaO+MgO+2H2O→Ca(OH)2+Mg(OH)2

[0024] Ca(OH)2+2HNO3→Ca(NO3)2+2H2O

[0025] Mg(OH)2+2HNO3→Mg(NO3)2+2H2O

[0026] The second solution provided by the present invention is:

[0027] A method for preparing amide calcium magnesium fertilizer comprises the following steps:

[0028] S1, add lime milk with a solid content of 40% to the calcium-magnesium solution for neutralization reaction to obtain a neutralized solution E;

[0029] Phosphorus will dissolve during the dilute nitric acid leaching process and can exist in the calcium-magnesium mixed solution in the form of phosphoric acid after combining with hydrogen in nitric acid. In this application, lime milk and calcium-magnesium solution undergo a neutralization reaction, and the main chemical reactions are:

[0030] Ca(OH)2+2HNO3→Ca(NO3)2+2H2O;

[0031] Ca(OH)2+H3PO4→CaHPO4+2H2O;

[0032] S2, filtering the neutralization liquid E to obtain the neutralization filter cake A and the calcium-magnesium neutralization liquid B;

[0033] Phosphorus in phosphate rock usually exists in the form of phosphorus pentoxide (P2O5). As the neutralization reaction proceeds, the pH in the system becomes neutral. As the neutralization solution E gradually becomes saturated, part of the phosphorus and P2O5 are precipitated. Similarly, calcium is precipitated in the form of CaO and magnesium is precipitated in the form of MgO. Therefore, the filtered cake A contains P2O5, CaO and MgO.

[0034] Calcium-magnesium neutralization solution B also contains dissolved calcium, magnesium, and nitrogen in the form of nitrate.

[0035] S3, heating and concentrating the calcium-magnesium neutralization solution B, wherein the calcium-magnesium neutralization solution B changes from yellow transparent to white, to obtain a calcium-magnesium concentrated solution C, wherein the calcium-magnesium concentrated solution C is a composite salt containing calcium, magnesium and nitrate; the main chemical reactions during the concentration process are:

[0036] Ca(NO3)2+Mg(NO3)2+xH2O→Ca(NO3)2·Mg(NO3)2·4H2O+

[0037] (x-4)H2O↑

[0038] S4. Take 50-60.6 parts of calcium magnesium concentrate C and 39.4-50 parts of urea, mix them evenly, heat to a molten state below 110°C to form amide calcium magnesium double salt; cool and granulate to obtain amide calcium magnesium fertilizer F.

[0039] The main chemical reactions in the production process of calcium magnesium amide double salt are:

[0040] Ca(NO3)2·Mg(NO3)2·4H2O+CO(NH2)2→Ca(NO3)2·Mg(NO3)2·

[0041] 4H2O·CO(NH2)2 or 10Ca(NO3)2·10Mg(NO3)2·40H2O·(6.5~10)CO(NH2)2;

[0042] In the method for preparing amide calcium magnesium fertilizer as described above, in step S1, pH is controlled to be 6.5-7.0, the temperature is 60-70° C., and the reaction is carried out for 1-2 hours.

[0043] In the method for preparing amide calcium magnesium fertilizer as described above, in step S3, the concentration temperature is 162-166°C.

[0044] In the method for preparing the calcium magnesium amide fertilizer as described above, the filter cake A is used to prepare a soil conditioner.

[0045] In the preparation method of amide calcium magnesium fertilizer as described above, the granulation temperature in step S4 is 90° C. to 103° C., the curing time is 20-25s, and the granulation method can be one of rotary drum fluidized bed, high tower granulation, disc granulation, steel belt granulation, etc.

[0046] An application of amide calcium magnesium fertilizer, in the process of planting agricultural fruit trees, using the amide calcium magnesium fertilizer or the amide calcium magnesium fertilizer F prepared by the preparation method of the amide calcium magnesium fertilizer as fertilizer.

[0047] The beneficial effects of the present invention are:

[0048] Amide calcium magnesium fertilizer contains nitrogen source, calcium ions and magnesium ions required for plant growth, which can increase the chlorophyll content in plants and promote plant growth;

[0049] In the preparation method of amide calcium magnesium fertilizer, the calcium magnesium liquid by-product produced in the nitric acid method of mineral processing is successively neutralized, concentrated and granulated to form amide calcium magnesium fertilizer, thereby improving the utilization rate of the calcium magnesium liquid.

[0050] In a fertilization method, the above-mentioned amide calcium magnesium fertilizer is used for fertilization, which can increase the chlorophyll content of the plant, increase the plant height value and increase the yield of the plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0052] Figure 1 is a graph showing the changing trend of the green SAPD value of amaranth leaves during the growth period in the treatment example of the present invention;

[0053] Figure 2 is a graph showing the variation trend of the plant height of Amaranth during the growth cycle in the treatment example of the present invention;

[0054] Figure 3 is a comparison diagram of the plant height of Amaranth in the treatment example of the present invention;

[0055] Figure 4 It is a finished product picture of the amide calcium magnesium fertilizer in the embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0057] The calcium-magnesium solution used in the following examples is a by-product of the nitric acid beneficiation process, and the mass percentages of nitrogen, P2O5, CaO, MgO, Fe2O3, and Al2O3 and the pH value thereof are shown in Table 1:

[0058] Table 1

[0059] project <![CDATA[N 总 %]]> <![CDATA[P2O5%]]> CaO% MgO% <![CDATA[Fe2O3%]]> <![CDATA[Al2O3%]]> pH Calcium and magnesium solution 3.24 0.11 4.65 0.98 0.0002 0.00 3.66

[0060] The mass percentage of urea nitrogen used in the following examples is: N 总 ≥46.0%;

[0061] Comparative Example 1:

[0062] A method for preparing amide calcium magnesium fertilizer comprises the following steps:

[0063] S1.d1, weigh 1000g of calcium-magnesium solution into a 2000mL beaker, control the speed at 88r / min, add lime milk with a solid content of 40% for neutralization reaction, control the pH to 6.5-7.0, the reaction temperature to 60-70°C, the reaction time to 1-2h, and obtain calcium-magnesium neutralization solution Ed1;

[0064] S2.d1, after the reaction is completed, use a circulating water multi-purpose vacuum pump (model SHB-Ⅲ, operating vacuum degree -0.08MPa, suction volume: 10L / min, ambient temperature range 5-35°C, size: 385W×280D×420H) to filter to obtain a neutralization filter cake Ad1 and a calcium-magnesium neutralization liquid Bd1;

[0065] S3.d1, weigh 300g of calcium-magnesium neutralization solution Bd1 into a porcelain dish, place it on a 2Kw electric furnace for heating and concentration, the concentration temperature is 162-166°C, observe that the calcium-magnesium neutralization solution Bd1 changes from yellow transparent to white, and obtain calcium-magnesium concentrated solution Cd1;

[0066] S4.d1. Take 57g of calcium magnesium concentrate Cd1 and 34.2g of urea, mix them evenly, heat them below 110°C to a molten state, and granulate them when the synthetic slurry is cooled to 90-103°C. The solidification time is 24-30s to obtain amide calcium magnesium fertilizer D1. Amide calcium magnesium fertilizer D1 is liquid and not granulated.

[0067] Comparative Example 2:

[0068] Steps S1.d2-S3.d2 in this comparative example are the same as S1.d1-S3.d1 in comparative example 1, except that:

[0069] S4.d2, take 57g of calcium magnesium concentrated liquid Cd2 and 35.3g of urea, mix them evenly, heat them below 110°C to a molten state, and granulate them when the synthetic slurry is cooled to 90-103°C. The solidification time is 24-30s to obtain amide calcium magnesium fertilizer D2. Amide calcium magnesium fertilizer D2 is liquid and does not granulate.

[0070] Embodiment 1:

[0071] Steps S1.1-S3.1 in this embodiment are the same as S1.d1-S3.d1 in Comparative Example 1, except that:

[0072] S4.1. Take 57g of calcium magnesium concentrate C1 and 36.4g of urea, mix them evenly, heat them to molten state at 109°C, and granulate them when the synthetic slurry is cooled to 90-96°C. The solidification time is 24-30s to obtain amide calcium magnesium fertilizer F1.

[0073] Embodiment 2:

[0074] Steps S1.2-S3.2 in this embodiment are the same as S1.d1-S3.d1 in Comparative Example 1, except that:

[0075] S4.2. Take 57g of calcium magnesium concentrate C2 and 39.9g of urea, mix them evenly, heat them to molten state at 108℃, and granulate them when the synthetic slurry is cooled to 90-94℃. The solidification time is 24s to obtain amide calcium magnesium fertilizer F2.

[0076] Embodiment 3:

[0077] Steps S1.3-S3.3 in this embodiment are the same as S1.d1-S3.d1 in Comparative Example 1, except that:

[0078] S4.3. Take 57g of calcium magnesium concentrate C3 and 45.6g of urea, mix them evenly, heat them to molten state at 109℃, and granulate them when the synthetic slurry is cooled to 90-93℃. The solidification time is 24s to obtain amide calcium magnesium fertilizer F3.

[0079] Embodiment 4:

[0080] Steps S1.4-S3.4 in this embodiment are the same as S1.1-S3.1 in Comparative Example 1, except that:

[0081] S4.4. Take 57g of calcium magnesium concentrate C4 and 51.3g of urea, mix them evenly, heat them to molten state at 109℃, and granulate them when the synthetic slurry is cooled to 91-103℃. The solidification time is 25s to obtain amide calcium magnesium fertilizer F4.

[0082] Embodiment 5:

[0083] Steps S1.5-S3.5 in this embodiment are the same as S1.1-S3.1 in Comparative Example 1, except that:

[0084] S4.4. Take 57g of calcium magnesium concentrate C5 and 51.3g of urea, mix them evenly, heat them to molten state at 108℃, and granulate them when the synthetic slurry is cooled to 94-90℃. The solidification time is 25s to obtain amide calcium magnesium fertilizer F5.

[0085] The appearance of calcium magnesium amide fertilizer F1-F5 is as follows Figure 4 As shown, the particles are white particles of uniform size and color.

[0086] The mass percentages of total nitrogen, nitrate nitrogen, amide nitrogen, CaO, MgO, aluminum, iron, manganese and free water in the amide calcium magnesium fertilizers F1-F5 in Examples 1-5 were determined, and the test data are shown in Table 2:

[0087] Table 2

[0088]

[0089] It can be seen that calcium-magnesium solution can be used to prepare N-containing 总 >27%、N 硝 >7%、N 酰胺>18%, CaO>12%, MgO>2% amide calcium magnesium series products; the products have the coordinated synergy of amide calcium and magnesium, which can improve product quality, improve soil (regulate soil pH), thereby enhancing crop photosynthesis, promoting fruit development and preventing fruit cracking; they also have the functions of protein and amino acid synthesis, meeting the needs of farmland and fruits for the supplement of nitrogen, calcium and magnesium.

[0090] Randomly select a group of amide calcium magnesium fertilizers in Examples 1-5 to measure the strength, such as amide calcium magnesium fertilizer F5, and obtain the average strength value of granulated amide calcium magnesium fertilizers, as shown in Table 3:

[0091] Table 3

[0092]

[0093] Since in this system, calcium magnesium liquid is a by-product produced during the nitric acid beneficiation process, the amount of purchased urea must be reduced to reduce the manufacturing cost of amide calcium magnesium fertilizer. It can be seen from the tests in Comparative Examples 1-2 and Examples 1-5 that when the calcium magnesium concentrate accounts for 60.6-50% and the urea accounts for 39.4-50%, both can be granulated and the strength can meet the requirements, which is the optimal manufacturing ratio of amide calcium magnesium fertilizer.

[0094] The calcium amide magnesium fertilizer prepared in this embodiment can be used for any kind of agricultural fruit trees (including forests, gardens, fruit trees, and flowers). The calcium amide magnesium fertilizer F5 is used for fertilizer efficiency test, and amaranth is used as the test object. The same amount of urea and calcium ammonium nitrate are used for comparative test. The basic physical and chemical properties of the test soil used are shown in Table 4:

[0095] Table 4

[0096]

[0097] Processing example 1:

[0098] The blank control group, the acupuncture application in the seedling stage and the topdressing application in the vigorous period were both 0g;

[0099] Processing example 2:

[0100] For the urea group, 2.0 g / pot of topdressing was applied in the seedling stage and 1.0 g / pot was applied in the vigorous growth stage.

[0101] Processing example 3:

[0102] For the calcium ammonium nitrate group, 2.0 g / pot of topdressing was applied in the seedling stage and 1.0 g / pot was applied in the vigorous growth stage.

[0103] Processing example 4:

[0104] For the amide calcium magnesium fertilizer group, amide calcium magnesium fertilizer F5 was used, with 2.0g / pot of topdressing applied in holes during the seedling stage and 1.0g / pot of topdressing applied in holes during the vigorous growth period.

[0105] Chlorophyll and plant height were measured before fertilization at the seedling stage, on the third day after fertilization at the seedling stage, before fertilization at the vigorous growth stage, on the third day after fertilization at the vigorous growth stage, and before harvest for treatment examples 2 to 4. Variance analysis and significant difference test (α=0.05) were performed using Duncan's new multivariate test method. The chlorophyll determination results are shown in Table 5 and Figure 1 The plant height measurement results are shown in Tables 6 and 2; the fresh weight of Amaranth plants was calculated after harvest, and the results are shown in Tables 7 and Figure 3 As shown;

[0106] The time points for measuring chlorophyll, plant height, fresh weight of amaranth plants and drying and inspection in treatment example 1 are the same as those in treatment examples 2 to 4;

[0107] Table 5

[0108]

[0109] As can be seen from Table 5, before fertilization at the seedling stage, the chlorophyll values ​​of amaranth in each treatment were not significantly different; on the third day after fertilization at the seedling stage, the chlorophyll value of treatment four was the highest, followed by treatment three, which was significantly different from treatment one; before fertilization during the vigorous growth period, the chlorophyll value of treatment four was the highest, followed by treatment three; on the third day after fertilization during the vigorous growth period, the chlorophyll value of treatment four was the highest, which was significantly different from treatment two and treatment one; before harvest, the chlorophyll value of treatment four was the highest, which was 7.11% and 3.56% higher than that of treatment two and treatment three, respectively; combined with Figure 1 As shown, the chlorophyll value of treatment four (amide calcium magnesium fertilizer) performed best overall.

[0110] Table 6

[0111]

[0112] As can be seen from Table 6, before fertilization at the seedling stage, there was no significant difference in the plant height of amaranth among the treatments; on the third day after fertilization at the seedling stage, the plant height of treatment three was the highest, followed by treatment two; before fertilization during the vigorous growth period, the plant height of treatment four was the highest, followed by treatment three; on the third day after fertilization during the vigorous growth period, the plant height of treatment four was the highest, followed by treatment three; before harvest, the plant height of treatment four was the highest, which was 3.0 cm and 2.4 cm higher than that of treatment two and treatment three, respectively; combined with Figure 3 As shown, the overall performance of amaranth plant height was the best in treatment four (amide calcium magnesium fertilizer).

[0113] Table 7

[0114]

[0115] It can be seen from Table 7 that among all the treatments, the amaranth yield in treatment four was the highest, which was 94.18 g, which was 10.74% and 4.15% higher than that in treatment two and treatment three, respectively.

[0116] In this experiment, treatment four (amide calcium magnesium fertilizer) had the best contribution to amaranth yield, and the yield was increased to varying degrees compared with treatment two (urea) and treatment three (calcium ammonium nitrate).

[0117] In summary, in the fertilizer efficiency test, treatment example 4 (i.e., the group applying amide calcium magnesium fertilizer) had the best overall chlorophyll value, the best overall performance of amaranth plant height, and the best contribution to amaranth yield.

[0118] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An amide calcium magnesium fertilizer, characterized in that The invention is composed of the following raw materials in parts by weight: 50 to 60.6 parts of calcium magnesium concentrate C and 39.4 to 50 parts of urea.

2. Amide calcium magnesium fertilizer as claimed in claim 1, characterized in that: The calcium-magnesium concentrated solution C is prepared by adding calcium-magnesium solution to an alkaline substance for neutralization and then concentrating the solution.

3. Amide calcium magnesium fertilizer as claimed in claim 1, characterized in that: The amide calcium magnesium fertilizer contains N 总 >27%.

4. Amide calcium magnesium fertilizer as claimed in claim 3, characterized in that: The amide calcium magnesium fertilizer contains nitrate nitrogen and amide nitrogen; wherein N 硝 >7%、N 酰胺 >18%.

5. The amide calcium magnesium fertilizer as claimed in any one of claims 1 to 4, characterized in that: The amide calcium magnesium fertilizer contains CaO and MgO, wherein CaO>12% and MgO>2%.

6. A method for preparing amide calcium magnesium fertilizer, characterized in that: The following steps are involved: S1, add lime milk with a solid content of 40% to the calcium-magnesium solution for neutralization reaction to obtain a neutralized solution E; S2, filtering the neutralization liquid E to obtain the neutralization filter cake A and the calcium-magnesium neutralization liquid B; S3, heating and concentrating the calcium-magnesium neutralization solution B, wherein the calcium-magnesium neutralization solution B changes from yellow transparent to white, to obtain a calcium-magnesium concentrated solution C; S4. Take 50-60.6 parts of calcium magnesium concentrate C and 39.4-50 parts of urea by weight, mix well, heat below 110°C to a molten state, cool and granulate to obtain amide calcium magnesium fertilizer F.

7. The preparation method of amide calcium magnesium fertilizer as claimed in claim 6, characterized in that: In the step S1, the pH is controlled at 6.5-7.0, the temperature is 60-70° C., and the reaction is carried out for 1-2 hours.

8. The preparation method of amide calcium magnesium fertilizer as claimed in claim 6, characterized in that: In step S3, the concentration temperature is 162°C-166°C.

9. The preparation method of amide calcium magnesium fertilizer as claimed in claim 6, characterized in that: The granulation temperature in step S4 is 90° C. to 103° C., and the curing time is 20 s to 25 s.

10. An application of amide calcium magnesium fertilizer, characterized in that: In the process of planting agricultural fruit trees, fertilization is performed using the amide calcium magnesium fertilizer as described in claims 1-5 or the amide calcium magnesium fertilizer F prepared by the preparation method of the amide calcium magnesium fertilizer as described in claims 6-9.

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