Method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid

Abstract

The invention discloses a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid, and belongs to the technical field of production of industrial diammonium hydrogen phosphate. The method solves the problem that the industrial-grade diammonium hydrogen phosphate product cannot be directly prepared by using crude phosphoric acid and ammonia gas as main raw materials. The method comprises the following steps: S1, mixing crude phosphoric acid and ammonia gas, and neutralizing for the first time, wherein the neutralization degree of the first time is 1.50-1.60; s2, filtering the material liquid obtained after the first time of neutralization; s3, concentrating the filtered material liquid, adding ammonia gas into the concentrated material liquid, and neutralizing for the second time with the neutralization degree of 1.95-2.0; and S4, cooling and crystallizing the material liquid obtained after the secondary neutralization to obtain an industrial-grade diammonium hydrogen phosphate product. The industrial-grade diammonium hydrogen phosphate product is produced by adopting a two-step neutralization method, so that the purpose of ammoniation impurity removal is achieved, heat release of ammoniation neutralization reaction is facilitated, the use of steam is reduced, the existing process is shortened, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial diammonium hydrogen phosphate production, and particularly relates to a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid. BACKGROUND

[0002] Industrial diammonium hydrogen phosphate (DAP), chemical formula (NH4)2HPO4, is an important inorganic compound and is widely used in agricultural and industrial fields. Diammonium hydrogen phosphate is usually synthesized by reacting ammonia gas with phosphoric acid. The specific steps include passing ammonia gas into phosphoric acid to generate diammonium hydrogen phosphate. The compound is relatively stable in air, but will gradually decompose and lose ammonia and water when heated to above 130 DEG C.

[0003] However, the existing production method of industrial diammonium hydrogen phosphate has the following defects:

[0004] 1. The neutralization reaction between crude phosphoric acid and ammonia gas produces fertilizer diammonium hydrogen phosphate product, which cannot directly produce industrial-grade diammonium hydrogen phosphate product;

[0005] 2. The neutralization reaction between hot-process phosphoric acid or purified phosphoric acid (H3PO4 concentration: 75%-85%) and ammonia gas produces diammonium hydrogen phosphate slurry, which is then concentrated, crystallized, separated, and dried to obtain industrial-grade diammonium hydrogen phosphate product. The disadvantages are: ① Since the impurities in crude phosphoric acid are high, direct neutralization, concentration, and crystallization with ammonia gas cannot produce industrial-grade diammonium hydrogen phosphate product, but only 64% or so of fertilizer-grade diammonium phosphate product. ② The use of hot-process phosphoric acid or purified phosphoric acid for neutralization to obtain industrial-grade diammonium hydrogen phosphate product results in high cost of industrial diammonium phosphate product due to the high price of hot-process phosphoric acid or purified phosphoric acid, and weak market competitiveness. SUMMARY

[0006] In view of the problem that the crude phosphoric acid and ammonia gas cannot be directly used as main raw materials to produce industrial-grade diammonium hydrogen phosphate product in the prior art, the application provides a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid.

[0007] The technical scheme adopted by the application is as follows:

[0008] A method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid, comprising the following steps:

[0009] S1: mixing crude phosphoric acid and ammonia gas for first neutralization, and the first neutralization degree is 1.50-1.60;

[0010] S2: filtering the obtained slurry after the first neutralization;

[0011] S3: concentrating the filtered slurry, and then adding ammonia gas for second neutralization after clarification of the concentrated filtrate, and the second neutralization degree is 1.95-2.0;

[0012] S4: obtaining industrial-grade diammonium hydrogen phosphate product after cooling and crystallization of the slurry obtained after the second neutralization.

[0013] As preferred, the specific gravity of the slurry obtained after concentration in S3 is 1.33-1.36.

[0014] As preferred, the temperature for crystallization in S4 is 30-45℃.

[0015] As preferred, the crude phosphoric acid is wet-process phosphoric acid with P2O5 concentration of 20-25%.

[0016] As preferred, the neutralization degree of the first time is 1.52.

[0017] As preferred, the neutralization degree of the second time is 1.97.

[0018] In summary, due to the adoption of the technical solutions described above, the present application has the following advantages:

[0019] The present application uses crude phosphoric acid to produce industrial-grade diammonium hydrogen phosphate product by two-step neutralization method, which not only achieves the purpose of ammoniation and impurity removal, but also benefits the heat release of ammonia neutralization reaction, reduces steam usage, shortens the existing wet-process phosphoric acid production industrial-grade diammonium hydrogen phosphate process, reduces equipment investment and power consumption, saves 1.5-2.0 tons of steam, saves 60-80 degrees of electricity, and reduces the comprehensive cost by nearly 500 yuan / ton. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The process flow chart of the present application;

[0021] Figure 2 The process flow chart of the existing process for preparing industrial-grade diammonium hydrogen phosphate. DETAILED DESCRIPTION

[0022] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] It should be noted that the "crude phosphoric acid" in the present application refers to wet-process phosphoric acid with P2O5 concentration of about 21%.

[0024] Embodiment 1

[0025] As shown in Figure 1 A method for producing industrial-grade diammonium hydrogen phosphate from crude phosphoric acid, comprising the following steps:

[0026] S1: Crude phosphoric acid with a P2O5 concentration of 21% and ammonia gas are mixed for the first neutralization, and the first degree of neutralization is 1.52;

[0027] S2: The liquid obtained after the first neutralization is filtered using a filter with a filter cloth having a pore size of 0.5 μm;

[0028] S3: The filtered liquid is concentrated, and the specific gravity of the slurry obtained after concentration is 1.33; ammonia is added to the concentrated liquid for a second neutralization, and the second neutralization degree is 1.97;

[0029] S4: Cooling and crystallizing the liquid obtained after the second neutralization at 30-45° C. for 50-60 minutes to obtain an industrial-grade diammonium hydrogen phosphate product.

[0030] Example 2

[0031] like Figure 1 As shown, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid comprises the following steps:

[0032] S1: Crude phosphoric acid with a P2O5 concentration of 22% and ammonia gas are mixed for the first neutralization, and the first degree of neutralization is 1.52;

[0033] S2: The liquid obtained after the first neutralization is filtered using a filter with a filter cloth having a pore size of 0.5 μm;

[0034] S3: The filtered liquid is concentrated, and the specific gravity of the concentrated slurry is 1.34; ammonia is added to the concentrated liquid for a second neutralization, and the second neutralization degree is 1.97;

[0035] S4: Cooling and crystallizing the liquid obtained after the second neutralization at 30-45° C. for 50-60 minutes to obtain an industrial-grade diammonium hydrogen phosphate product.

[0036] Example 3

[0037] like Figure 1 As shown, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid comprises the following steps:

[0038] S1: Crude phosphoric acid with a P2O5 concentration of 23% and ammonia gas are mixed for the first neutralization, and the first degree of neutralization is 1.52;

[0039] S2: The liquid obtained after the first neutralization is filtered using a filter with a filter cloth having a pore size of 0.5 μm;

[0040] S3: The filtered feed liquid is concentrated, and the specific gravity of the slurry obtained after concentration is 1.35; the concentrated feed liquid is added with ammonia gas for second neutralization, and the second neutralization degree is 1.97;

[0041] S4: The feed liquid obtained after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain the industrial-grade diammonium hydrogen phosphate product.

[0042] Example 4

[0043] As shown in the following table, a method for producing industrial-grade diammonium hydrogen phosphate from crude phosphoric acid includes the following steps: Figure 1

[0044] S1: The crude phosphoric acid with a P2O5 concentration of 24% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.52;

[0045] S2: The feed liquid obtained after the first neutralization is filtered by using a filter cloth with a pore size of 0.5μ;

[0046] S3: The filtered feed liquid is concentrated, and the specific gravity of the slurry obtained after concentration is 1.36; the concentrated feed liquid is added with ammonia gas for second neutralization, and the second neutralization degree is 1.97;

[0047] S4: The feed liquid obtained after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain the industrial-grade diammonium hydrogen phosphate product.

[0048] Example 5

[0049] As shown in the following table, a method for producing industrial-grade diammonium hydrogen phosphate from crude phosphoric acid includes the following steps: Figure 1

[0050] S1: The crude phosphoric acid with a P2O5 concentration of 25% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.52;

[0051] S2: The feed liquid obtained after the first neutralization is filtered by using a filter cloth with a pore size of 0.5μ;

[0052] S3: The filtered feed liquid is concentrated, and the specific gravity of the slurry obtained after concentration is 1.38; the concentrated feed liquid is added with ammonia gas for second neutralization, and the second neutralization degree is 1.97;

[0053] S4: The feed liquid obtained after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain the industrial-grade diammonium hydrogen phosphate product.

[0054] Comparative Example 1

[0055] As shown in the following table, a method for producing industrial-grade diammonium hydrogen phosphate from crude phosphoric acid includes the following steps:​​Figure 1 As shown in the figure, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid includes the following steps:

[0056] S1: crude phosphoric acid with a P2O5 concentration of 20.5% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.62;

[0057] S2: the obtained solution after the first neutralization is filtered by a filter with a pore size of 0.5 μm;

[0058] S3: the filtered solution is concentrated, and the specific gravity of the concentrated solution is 1.30; ammonia gas is added to the concentrated solution for second neutralization, and the second neutralization degree is 1.97;

[0059] S4: the obtained solution after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain industrial-grade diammonium hydrogen phosphate product.

[0060] Comparative Example 2

[0061] As shown in the figure, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid includes the following steps: Figure 1

[0062] S1: crude phosphoric acid with a P2O5 concentration of 21.5% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.62;

[0063] S2: the obtained solution after the first neutralization is filtered,

[0064] S3: the filtered solution is concentrated, and the specific gravity of the concentrated solution is 1.31; ammonia gas is added to the concentrated solution for second neutralization, and the second neutralization degree is 1.97;

[0065] S4: the obtained solution after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain industrial-grade diammonium hydrogen phosphate product.

[0066] Comparative Example 3

[0067] As shown in the figure, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid includes the following steps: Figure 1

[0068] S1: crude phosphoric acid with a P2O5 concentration of 22.5% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.62;

[0069] S2: the obtained solution after the first neutralization is filtered,

[0070] ​​S3: The filtered feed liquid is concentrated, and the specific gravity of the concentrated feed liquid is 1.32; the concentrated feed liquid is added with ammonia gas for second neutralization, and the second neutralization degree is 1.97;

[0071] S4: The feed liquid obtained after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain the industrial-grade diammonium hydrogen phosphate product.

[0072] Comparative Example 4

[0073] As shown in the following, Figure 1 a method for producing industrial-grade diammonium hydrogen phosphate from crude phosphoric acid, comprising the following steps:

[0074] S1: The crude phosphoric acid with a P2O5 concentration of 23.5% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.62;

[0075] S2: The feed liquid obtained after the first neutralization is filtered,

[0076] S3: The filtered feed liquid is concentrated, and the specific gravity of the concentrated feed liquid is 1.33; the concentrated feed liquid is added with ammonia gas for second neutralization, and the second neutralization degree is 1.97;

[0077] S4: The feed liquid obtained after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain the industrial-grade diammonium hydrogen phosphate product.

[0078] Comparative Example 5

[0079] As shown in the following, Figure 1 a method for producing industrial-grade diammonium hydrogen phosphate from crude phosphoric acid, comprising the following steps:

[0080] S1: The crude phosphoric acid with a P2O5 concentration of 24.5% is mixed with ammonia gas for first neutralization, and the first neutralization degree is 1.62;

[0081] S2: The feed liquid obtained after the first neutralization is filtered,

[0082] S3: The filtered feed liquid is concentrated, and the specific gravity of the concentrated feed liquid is 1.34; the concentrated feed liquid is added with ammonia gas for second neutralization, and the second neutralization degree is 1.97;

[0083] S4: The feed liquid obtained after the second neutralization is cooled and crystallized at 30-45°C for 50-60 min to obtain the industrial-grade diammonium hydrogen phosphate product.

[0084] Comparative Example 6

[0085] As shown in the following, Figure 1As shown, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid comprises the following steps:

[0086] S1: Crude phosphoric acid with a P2O5 concentration of 25.5% and ammonia gas are mixed for the first neutralization, and the first degree of neutralization is 1.52;

[0087] S2: Filter the liquid obtained after the first neutralization.

[0088] S3: The filtered liquid is concentrated, and the specific gravity of the concentrated liquid is 1.31; ammonia is added to the concentrated liquid for a second neutralization, and the second neutralization degree is 1.97;

[0089] S4: Cooling and crystallizing the liquid obtained after the second neutralization at 30-45° C. for 50-60 minutes to obtain an industrial-grade diammonium hydrogen phosphate product.

[0090] Comparative Example 7

[0091] like Figure 1 As shown, a method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid comprises the following steps:

[0092] S1: Crude phosphoric acid with a P2O5 concentration of 22.0% and ammonia gas are mixed for the first neutralization, and the first neutralization degree is 1.50;

[0093] S2: Filter the liquid obtained after the first neutralization.

[0094] S3: The filtered liquid is concentrated, and the specific gravity of the concentrated liquid is 1.33; ammonia is added to the concentrated liquid for a second neutralization, and the second neutralization degree is 1.97;

[0095] S4: Cooling and crystallizing the liquid obtained after the second neutralization at 30-45° C. for 50-60 minutes to obtain an industrial-grade diammonium hydrogen phosphate product.

[0096] The variables and effects of Examples 1-5 and Comparative Examples 1-7 are shown in Table 1 below:

[0097] Table 1

[0098]

[0099]

[0100] As can be seen from Table 1, in this application, by strictly controlling the first degree of neutralization, the second degree of neutralization, the specific gravity of the concentrated slurry and the crystallization temperature, the proportion of crystalline particles with a particle size of (20-60) mesh in the crystallized product can reach 75% or more.

[0101] The method of the application effectively reduces the cost of preparing industrial-grade diammonium hydrogen phosphate product. The cost accounting data of the existing process (the approximate process of preparing industrial-grade diammonium hydrogen phosphate by the existing process is shown in Figure 2 Table 2 shows the cost accounting data of the existing process, and Table 3 shows the specific cost accounting data of the application:

[0102] Table 2

[0103]

[0104] Table 3

[0105]

[0106] As can be seen from Tables 2 and 3, after using the process, only 2 tons of steam are consumed per ton of industrial-grade diammonium hydrogen phosphate produced, while in the prior art, 3.5 tons of steam are consumed per ton of industrial-grade diammonium hydrogen phosphate produced, i.e. the amount of steam is reduced by 42.85%; in terms of total cost, the cost of the process is 4137.07 yuan / ton, while the cost of the existing process is 4628.16 yuan / ton, which is reduced by 491.09 yuan / ton, i.e. the cost is reduced by 10.61% compared with the existing process.

[0107] In order to prove that the product obtained in Example 1 of the application meets the characterization of industrial-grade diammonium hydrogen phosphate, the product was also subjected to component detection, and the results are shown in Table 4:

[0108] Table 4

[0109]

[0110]

[0111] As can be seen from Table 4, the diammonium hydrogen phosphate prepared by the application meets the industry standard of existing industrial-grade diammonium hydrogen phosphate.

[0112] The above-described embodiments only express the specific implementation of the application, which is described in detail and specifically, but should not be construed as limiting the scope of protection of the application. It should be noted that for ordinary skilled persons in the art, without departing from the technical concept of the application, a number of modifications and improvements can be made, which are within the scope of protection of the application.

Claims

1. A method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid, characterized in that: The following steps are involved: S1: Mix crude phosphoric acid and ammonia gas for the first neutralization, and the first neutralization degree is 1.50-1.60; S2: Filtering the liquid obtained after the first neutralization; S3: Concentrating the filtered liquid, adding ammonia to the concentrated liquid for a second neutralization, and the second neutralization degree is 1.95-2.0; S4: Cooling and crystallizing the liquid obtained after the second neutralization to obtain an industrial-grade diammonium hydrogen phosphate product.

2. The method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid according to claim 1, wherein: The specific gravity of the slurry obtained after concentration in S3 is 1.33-1.

36.

3. The method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid according to claim 2, wherein: The temperature of crystallization in S4 is 30-45°C.

4. The method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid according to claim 2, wherein: The crude phosphoric acid is wet-process phosphoric acid with a P2O5 concentration of 20-25%.

5. The method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid according to claim 1, wherein: The first neutralization degree was 1.

52.

6. The method for producing industrial diammonium hydrogen phosphate from crude phosphoric acid according to claim 1, wherein: The second neutralization degree was 1.97.

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