CN104310340B - Method for preparing ammonium dihydrogen phosphate and preparing special fertilizer for beet as byproduct - Google Patents

Abstract

The invention relates to the field of chemical technology, in particular to a production method for preparing ammonium dihydrogen phosphate by-product beet special fertilizer. By changing the temperature and other coefficients of preparing ammonium dihydrogen phosphate by wet-process phosphoric acid, the purity of ammonium dihydrogen phosphate product is improved , at the same time can produce compound fertilizer containing N, P, K compound state, this method can not only improve the purity of ammonium dihydrogen phosphate, the absorption rate of the special fertilizer for sugar beet produced is good, and the special fertilizer for sugar beet produced at the same time It can meet the nutritional needs of each stage in the sugar beet growth cycle, greatly increase the sugar beet yield, and is a highly efficient compound fertilizer.

Description

A kind of production method for preparing ammonium dihydrogen phosphate by-product sugar beet special fertilizer

technical field

The invention relates to the technical field of chemical industry, in particular to a production method for preparing ammonium dihydrogen phosphate by-product special fertilizer for sugar beets.

Background technique

Beet, (Beta vulgaris), also known as beet vegetable, is a biennial herb native to the western and southern coasts of Europe, transplanted from Sweden to Spain, and is a major source of sugar other than tropical sugarcane. The pigment content of beetroot is extremely rich. The main pigment is called Betalains, including red Betacyanins and yellow Betaxanthins. Pigment is a good source of pigment.

At present, the seed fertilizer used for sugar beets in China is basically diammonium phosphate, which is also a seed fertilizer commonly used in agriculture. Its main components are phosphorus pentoxide (P2O5) 46%, nitrogen (N) 18%. Because different crops have different nutrient absorption rules and sensitivities, there are many problems in the application of DAP on sugar beets. For example, the nitrogen content in DAP is relatively high, while the beet seed buds are relatively weak, which often occurs in the soil. Ammonia (NH3) burns the seed buds. In mild cases, seedlings are missing and ridges are broken. In severe cases, there are no seedlings in large areas.

The high nitrogen content in diammonium phosphate can promote the growth of beet seedlings, especially the vigorous growth center of nitrogen metabolism continues above the ground. This situation is not conducive to the extension of beet young roots to the ground, so the beet growth appears shorter root shape, The sugar content of sugar beets decreased when the root head increased. Sugar beet is the use of beet root, the above phenomenon directly affects the economic benefits of sugar factories.

At present, the sugar beet production areas in my country are mainly concentrated in the Northeast, North China, and Northwest regions. These areas are all calcareous soils. Because calcium and water-soluble phosphorus in calcareous soils have a fixed effect, the available phosphate-calcium is transformed into difficult to be used by sugar beets. Octacalcium Phosphate. Therefore, a large amount of phosphorus in diammonium phosphate is fixed by calcium in the soil, and the utilization rate is very low, generally 10-20%. Therefore, although the content of diammonium phosphate is very high, its effect is not ideal, and increasing the application of diammonium phosphate will cause the danger of burning the seed buds. After many years of experiments on the amount of diammonium phosphate fertilization, increasing the application of diammonium phosphate has no effect on increasing production and sugar. On the contrary, as the amount of diammonium phosphate increases, the sugar content decreases.

In the process of producing ammonium dihydrogen phosphate, the purity of ammonium dihydrogen phosphate is not high, and the filtrate also contains a large amount of unseparated carbonamide, H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3- and other substances. Based on a large number of existing technical documents and years of exploration and research, the researchers also studied the composition content of traditional sugar beet special fertilizers and the absorption of sugar beets, and effectively explored the production of ammonium dihydrogen phosphate from the filtrate of wet-process phosphoric acid. Take beet special fertilizer to solve the problems of low purity of ammonium dihydrogen phosphate produced by wet process phosphoric acid and unusable active ingredients in the filtrate. At the same time, the special fertilizer has good absorption rate and controlled release effect. In domestic fertilizer production, it has not been used. See report.

Contents of the invention

Aiming at the above technical problems, the present invention provides a production method for preparing ammonium dihydrogen phosphate by-product special fertilizer for sugar beet, through a unique process production design, the purity of ammonium dihydrogen phosphate is improved, and at the same time, wet-process phosphoric acid is fully utilized to produce dihydrogen phosphate The active ingredient of ammonium is used to produce a special fertilizer for beet that is suitable for the growth of beet.

The present invention is achieved through the following technical solutions:

A kind of production method of preparing ammonium dihydrogen phosphate by-product sugar beet special fertilizer provided by the invention mainly comprises the following steps:

1) Mix phosphoric acid and carbonamide, and raise the temperature from 80°C to 160°C at a heating rate of 3-8°C/min, stir and react for 4-5h, separate the intermediate, then add the intermediate to the ammonia solution, and adjust the temperature to 50-65°C, stirring and reacting for 2-3 hours, after the reaction, conduct cooling crystallization and filtration treatment, the crystallization temperature is 30-35°C, and circulate the filtrate in the cooling crystallizer for crystallization treatment, and the obtained filter cake is ammonium dihydrogen phosphate Products, detect the content of ingredients in the filtrate;

2) Add potassium hydroxide solution and phosphoric acid solution to the filtrate to adjust the middle pH value and nitrogen, phosphorus and potassium content of the filtrate. When the potassium content is 4-8% and the potassium content is 10-15%, stop adding potassium hydroxide solution and phosphoric acid solution, then add formaldehyde solution to the solution, raise the temperature to 50-65°C, and stir for 2.5-4 hours;

3) Add medium elements such as calcium and magnesium and trace elements such as borax, zinc sulfate, manganese sulfate, and cobalt nitrate to the filtrate, and stir for 1 to 1.5 hours;

4) cooling the solution obtained in step 3) to 15-20°C, and performing crystallization treatment to obtain the primary product of compound fertilizer, which contains Potassium phosphate compound fertilizer for roots.

5) Granulate the primary product of the combined compound fertilizer, and then dry it in an environment of 45-55°C to make a special fertilizer for sugar beet.

The molar ratio of phosphoric acid and carbonamide is (1.2-1.5):1.

The molar ratio of the added intermediate to ammonia water is 1: (1.2-1.4).

The concentration of the potassium hydroxide solution is 10-15%.

The concentration of the phosphoric acid solution is 10-15%.

The crystallization treatment is as follows: stop crystallization when the content of the nitrogen component in the primary product of the combined compound fertilizer is 18-23%, the content of the phosphorus component is 3-6%, and the content of the potassium component is 8-13%.

The first finished product of the compound state compound fertilizer is rich in and of controlled-release fertilizers, of which and The molar ratio is 1:(2~4).

In the present invention, carbonamide and phosphoric acid are reacted at 80°C and heated up to 160°C at a rate of 5°C/min to form urea phosphate, and as the temperature gradually increases, the urea phosphate The coordination bonds of the two ionic substances are broken, that is, and when Ions in the phosphoric acid environment will be close to phosphoric acid, and then carry out ion polymerization reaction under the temperature environment when the urea phosphate coordination bond is broken, so that Ion and Phosphoric Acid Formation At the same time, the solution contains a large amount of dihydrogen phosphate. When ammonia water is added, the dihydrogen phosphate reacts with potassium ions to form ammonium dihydrogen phosphate, which successively reaches saturation; when NH ₄ ·H ₂ PO ₄ crystals are precipitated , the filtrate contained a large amount of root, adding potassium hydroxide solution to the filtrate, when the potassium ion content is excessive, it will react with the ammonium ion in the intermediate ion, and further make the intermediate ion chelate into The intermediate ion has a positive charge, and when the solution participates in other negatively charged ions or compounds, it will form a double salt compound with the ion, further enriching the nutritional content of the product.

At the same time, under the acidic condition of pH 3.5-4.0, carbonamide will react with formaldehyde solution to produce urea-formaldehyde series products or even longer chemical chains, It will continue to react with carbonamide and formaldehyde under acidic conditions to form Simultaneously It continues to react with carbonamide and formaldehyde under acidic conditions, so the reaction time is controlled at 2.5 to 4 hours to ensure that the and The molar ratio is 1:(2～4), or After the urea-formaldehyde series products are fertilized, under the action of microorganisms, they will release N and C elements that are easily absorbed by plants. The longer the chain length of urea-formaldehyde, the longer the chain needs to be broken, and the time to produce fertilizer effect will be in a certain period. Released after a period of time, it can achieve the effect of sustained release. In general, The release time of fertilizer effect is 0-40 days, The release time of fertilizer effect is 40-80 days.

The beneficial effects of the present invention are:

Compared with the prior art, the present invention has the following characteristics:

①The filtrate of ammonium dihydrogen phosphate produced by conventional wet process phosphoric acid is rich in carbonamide solution. The solubility of carbonamide at the same temperature is relatively large, and the separated carbonamide crystals are rich in NH ₄ ·H ₂ PO ₄ and other crystals, and at the same time, the filtrate after cooling down to precipitate carbonamide crystals also contains a large amount of carbonamide, H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3- , etc., which have not been effectively utilized. The present invention prepares phosphoric acid from wet-process phosphoric acid The temperature of ammonium dihydrogen phosphate is adjusted to 80-160°C, and the temperature is raised from 80°C to 160°C at a rate of 5°C/min. After adding strong potassium oxide solution, the filtrate also produced When the compounded compound fertilizer produced by crystallization of the filtrate is produced as a finished product, it ensures that the compounded compound fertilizer is produced in the finished product The intermediate ion and dihydrogen phosphate form a coordination bond between C and O. This intermediate ion can chelate with the middle element compound to form a multi-element intermediate ion, which can then continue to interact with other negatively charged compounds or ions Form a chelate, increase the content of elements in the double salt, and then adjust the nutrient content in the double salt where the ion exists. At the same time, the chelate can be hydrolyzed to be used by crops, which can effectively provide fertilizer for crops for a long time. At the same time, combined with the determination of the element content in the solution in which the ion exists, the content of each element when the double salt is formed is adjusted, and the compound state double salt compound fertilizer is obtained by drying. The absorption rate is excellent, which reduces the sugar beet planting cost and improves sugar beet quality;

②The filtrate contains part of the carbonamide component, adding formaldehyde solution, under acidic conditions and a certain pressure and temperature, to form or Such as urea-formaldehyde series compound fertilizer can make the special fertilizer for sugar beet achieve the effect of controlled release;

③Through the detection and analysis of the element content in the beet special fertilizer and the effective absorption of nitrogen, phosphorus and potassium elements by the beet, and the adjustment and matching of the element content in the production process, the prepared compound fertilizer can maximize It meets the needs of crops to the maximum extent, and reduces the excessive cost caused by improper combination of elements in the production of compound fertilizers, and further avoids putting too many elements into the soil, causing the solidification of compound fertilizers and polluting the environment.

detailed description

The specific technical solutions of the present invention will be described in detail below in conjunction with specific embodiments.

Principle description:

The present invention studies and discusses the mechanism of the reaction between phosphoric acid and carbonamide, and combines the prior art literature to understand that phosphoric acid and carbonamide react to form urea phosphate, and its molecular formula is: CO(NH ₂ ) ₂ .H ₃ PO ₄ , In a higher temperature environment, the chemical bond between H and O in phosphoric acid will be broken, and hydrogen ions will combine with carbonamide to form a positively charged ionic state, making urea phosphate form an ion complex that attracts positive and negative charges. Salt, its mechanism structure reaction is as follows: CO(NH ₂ ) ₂ .H ₃ PO ₄ →(H ₂ PO ₄ ) ^- .(H ₂ NCONH ₃ ) ⁺

Furthermore, in the presence of phosphoric acid in the presence of phosphoric acid, the (H ₂ NCONH ₃ ) ⁺ positive ion in the double salt of urea phosphate ion is close to phosphoric acid to form the intermediate ion of the C→O coordination bond, which is (CO ₅ PN ₂ H ₈ ) ⁺ , so that the urea phosphate intermediate contains a large amount of (H ₂ PO ₄ ) ^- and (CO ₅ PN ₂ H ₈ ) ⁺ ions. Ammonium dihydrogen phosphate crystals are precipitated, excess potassium ions react with (CO ₅ PN ₂ H ₈ ) ⁺ ions, and replace part of NH ₄ ⁺ , so that the solution contains (CO ₅ PNH ₄ K) ⁺ double salt ions, And by detecting, analyzing and controlling the content of N, P, and K elements in the solution, the compound fertilizer containing N, P, and K elements can be obtained after heating and drying.

Its specific reaction principle will be further explained by the following reaction structural formula and reaction mechanism:

Reaction formula one:

CO(NH ₂ ) ₂ +H ₃ PO ₄ →CO(NH ₂ ) ₂ .H ₃ PO ₄

Reaction two:

Reaction three:

Wherein, the dotted line between the carbon atom and the oxygen atom indicates that there is a coordination bond between the C atom and the O atom.

When ammonia water is added, dihydrogen phosphate reacts with potassium ions to form ammonium dihydrogen phosphate, which successively reaches saturation; when NH ₄ ·H ₂ PO ₄ crystals are precipitated, the filtrate contains a large amount of Root, potassium hydroxide solution is added in the filtrate, when the potassium ion content is excessive, will react with the ammonium root ion in the intermediate ion.

Reaction four:

Wherein, the dotted line between the carbon atom and the oxygen atom indicates that there is a coordination bond between the C atom and the O atom.

In the present invention, carbonamide and formaldehyde will produce the following reactions at a pH of 3.5 to 4.0 and a temperature of 50 to 65°C:

Reaction five

Reaction six

Generate urea-formaldehyde series products or even longer chemical chains, It will continue to react with carbonamide and formaldehyde under acidic conditions to form Simultaneously It continues to react with carbonamide and formaldehyde under acidic conditions, so the reaction time is controlled at 2.5 to 4 hours to ensure that the and The molar ratio is 1:(2～4), or After fertilization, urea-formaldehyde series products will release N and C elements that are easily absorbed by plants under the action of microorganisms. The longer the chain length of urea-formaldehyde, the longer the chain needs to be broken, and the time to produce fertilizer effect will be in a certain period. Released after a period of time, it can achieve the effect of sustained release. In general, The release time of fertilizer effect is 0-40 days, The release time of fertilizer effect is 40-80 days.

Noun description:

Ureaphosphate (UP), CAS No. 4861-19-2, molecular formula CH ₇ N ₂ O ₅ P, can be expressed as CO(NH ₂ ) ₂ ·H ₃ PO ₄ :

It is a fine chemical product widely used in animal husbandry, industry, agriculture and other fields. Its solid is white crystal or crystalline powder, soluble in water and alcohol, insoluble in ether, toluene and carbon tetrachloride, and its aqueous solution is It is acidic and starts to decompose when melting to release carbon dioxide and ammonia.

Embodiment one

A kind of production method of preparing ammonium dihydrogen phosphate by-product sugar beet special fertilizer provided by the present embodiment mainly comprises the following steps:

1) Phosphoric acid and carbonamide are mixed, the molar ratio of phosphoric acid and carbonamide is 1.2:1, and the temperature is raised from 80°C to 160°C at a heating rate of 3-8°C/min, stirred and reacted for 4-5h, and separated to obtain Intermediate, then add the intermediate to the aqueous ammonia solution, the molar ratio of the intermediate to the ammonia water is 1:1.4, adjust the temperature to 50-65°C, stir and react for 2-3 hours, after the reaction, carry out cooling crystallization and filtration , the crystallization temperature is 30-35°C, the filtrate is circulated and crystallized in the cooling crystallizer, the obtained filter cake is ammonium dihydrogen phosphate product, and the component content in the filtrate is detected;

2) add potassium hydroxide solution and phosphoric acid solution in filtrate, adjust the middle pH value and nitrogen, phosphorus, potassium content of filtrate, the concentration of described potassium hydroxide solution is 10%, the concentration of described phosphoric acid solution is 15% %, when the filtrate pH value is 3.5～4, the content of nitrogen component is 20-25%, phosphorus component content is 4-8%, when potassium component content is 10-15%, stop adding potassium hydroxide solution and phosphoric acid solution, Then add formaldehyde solution into the solution, raise the temperature to 50-65°C, and stir for 2.5 hours;

3) Add medium elements such as calcium and magnesium and trace elements such as borax, zinc sulfate, manganese sulfate, and cobalt nitrate to the filtrate, and stir for 1 to 1.5 hours;

4) The solution obtained in step 3) is cooled to 15-20° C., and crystallized to obtain the first product of compound fertilizer, when the content of nitrogen component in the first product of compound fertilizer is 18%, and the content of phosphorus component is Crystallization stops when the potassium content is 6% and 8%.

5) Granulate the primary product of the combined compound fertilizer, and then dry it in an environment of 45-55°C to make a special fertilizer for sugar beets.

After testing, the purity of the prepared ammonium dihydrogen phosphate reaches over 97%, and the prepared special fertilizer for sugar beet contains Potassium phosphate compound fertilizer for roots, and containing and of controlled-release fertilizers, of which and The molar ratio is 1:2.

Embodiment two

A kind of production method of preparing ammonium dihydrogen phosphate by-product sugar beet special fertilizer provided by the present embodiment mainly comprises the following steps:

1) Phosphoric acid and carbonamide are mixed, the molar ratio of phosphoric acid and carbonamide is 1.5:1, and the temperature is raised from 80°C to 160°C at a heating rate of 3-8°C/min, stirred for 4-5h, and separated to obtain Intermediate, then add the intermediate to the aqueous ammonia solution, the molar ratio of the intermediate to the ammonia water is 1:1.2, adjust the temperature to 50-65°C, stir and react for 2-3 hours, after the reaction is completed, carry out cooling crystallization and filtration , the crystallization temperature is 30-35°C, the filtrate is circulated and crystallized in the cooling crystallizer, the obtained filter cake is ammonium dihydrogen phosphate product, and the component content in the filtrate is detected;

2) add potassium hydroxide solution and phosphoric acid solution in filtrate, adjust the middle pH value and nitrogen, phosphorus, potassium content of filtrate, the concentration of described potassium hydroxide solution is 15%, the concentration of described phosphoric acid solution is 10% %, when the filtrate pH value is 3.5～4, the content of nitrogen component is 20-25%, phosphorus component content is 4-8%, when potassium component content is 10-15%, stop adding potassium hydroxide solution and phosphoric acid solution, Then add formaldehyde solution into the solution, raise the temperature to 50-65°C, and stir for 4 hours;

3) Add medium elements such as calcium and magnesium and trace elements such as borax, zinc sulfate, manganese sulfate, and cobalt nitrate to the filtrate, and stir for 1 to 1.5 hours;

4) The solution obtained in step 3) is cooled to 15-20° C., and crystallization treatment is carried out to obtain the first product of compound fertilizer. When the content of nitrogen component in the first product of compound fertilizer is 23%, the content of phosphorus component is Crystallization stops at 3% and potassium content of 13%.

5) Granulate the primary product of the combined compound fertilizer, and then dry it in an environment of 45-55°C to make a special fertilizer for sugar beets.

After testing, the purity of the prepared ammonium dihydrogen phosphate reaches over 97%, and the prepared special fertilizer for sugar beet contains Potassium phosphate compound fertilizer for roots, and containing and of controlled-release fertilizers, of which and The molar ratio is 1:3.

Embodiment three

A kind of production method of preparing ammonium dihydrogen phosphate by-product sugar beet special fertilizer provided by the present embodiment mainly comprises the following steps:

1) Phosphoric acid and carbonamide are mixed, the molar ratio of phosphoric acid and carbonamide is 1.4:1, and the temperature is raised from 80°C to 160°C at a heating rate of 3-8°C/min, stirred and reacted for 4-5h, and separated to obtain Intermediate, then add the intermediate to the aqueous ammonia solution, the molar ratio of the intermediate to the ammonia water is 1:1.3, adjust the temperature to 50-65°C, stir and react for 2-3 hours, after the reaction is completed, carry out cooling crystallization and filtration , the crystallization temperature is 30-35°C, the filtrate is circulated and crystallized in the cooling crystallizer, the obtained filter cake is ammonium dihydrogen phosphate product, and the component content in the filtrate is detected;

2) add potassium hydroxide solution and phosphoric acid solution in filtrate, adjust the middle pH value and nitrogen, phosphorus, potassium content of filtrate, the concentration of described potassium hydroxide solution is 13%, the concentration of described phosphoric acid solution is 12% %, when the filtrate pH value is 3.5～4, the content of nitrogen component is 20-25%, phosphorus component content is 4-8%, when potassium component content is 10-15%, stop adding potassium hydroxide solution and phosphoric acid solution, Then add formaldehyde solution into the solution, raise the temperature to 50-65°C, and stir for 3 hours;

3) Add medium elements such as calcium and magnesium and trace elements such as borax, zinc sulfate, manganese sulfate, and cobalt nitrate to the filtrate, and stir for 1 to 1.5 hours;

4) The solution obtained in step 3) is cooled to 15-20° C., and crystallization treatment is carried out to obtain the first product of compound fertilizer. When the content of nitrogen component in the first product of compound fertilizer is 21%, the content of phosphorus component is Crystallization stops at 5% and potassium content of 11%.

5) Granulate the primary product of the combined compound fertilizer, and then dry it in an environment of 45-55°C to make a special fertilizer for sugar beet.

After testing, the purity of the prepared ammonium dihydrogen phosphate reaches over 97%, and the prepared special fertilizer for sugar beet contains Potassium phosphate compound fertilizer for roots, and containing and of controlled-release fertilizers, of which and The molar ratio is 1:4.

In order to better prove the beneficial effects achieved by the present invention, the present embodiment also provides the following experimental examples, specifically as follows:

Experimental example one

Common N, P, K mixed fertilizers are used as fertilizers, wherein the content of nitrogen components is 21%, the content of phosphorus components is 5%, and the content of potassium components is 11%, and a culture solution is used for soilless cultivation of sugar beets. After 30 days, detect the contents of N, P, and K components in the culture solution, and observe its growth at the same time, and name it A1.

Experimental Example 2 to Experimental Example 4

The sugar beet special fertilizer successfully made by the method of embodiment one to embodiment three is used as fertilizer, and culture liquid is made, and sugar beet is carried out soilless cultivation, and after cultivating for 15 days, 30 days, and 50 days, respectively detect N, P, The content of K component, while observing its growth, are named A2, A3, A4 respectively.

The concentration of the nutrient solution in the above experimental example is suitable, is prior art, and this experimental example is not many elaborated, and above experimental example takes 20 sugar beet as detection result such as table 1, table 2 and table 3:

Table 1: Contents of N, P, and K components after 15 days of culture

Table 2: Contents of N, P, and K components after 30 days of culture

Table 3: Contents of N, P, and K components after 50 days of culture

As can be seen from Tables 1 to 3, compared with the sugar beet special fertilizer produced by the present invention, the absorption of N, P, and K in the 15th day of cultivation has little difference with common compound fertilizers, but by the 30th day When detecting, the content of N, P and K in the special fertilizer solution for sugar beet produced by the present invention is obviously lower than that of common special fertilizer, and when detecting on the 50th day, the N, P and K components in the common compound fertilizer nutrient solution remain Have 60～80% to be unabsorbed, and the N, P, K composition in the nutrient solution of the sugar beet special fertilizer produced by the present invention only have 30～40% to be unabsorbed, illustrate that the sugar beet special fertilizer produced by the present invention has good absorption rate specialty.

Claims (7)

1. prepare a production method for ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, mainly comprise the steps that

1) use phosphoric acid to mix with phosphoamide, and be that 3～8 DEG C/min is warming up to 160 DEG C from 80 DEG C with programming rate, stirring reaction 4-5h, isolated intermediate, then intermediate is added in ammonia spirit, temperature is adjusted to 50～65 DEG C, stirring reaction 2～3h, After reaction terminates, carrying out crystallisation by cooling filtration treatment, crystallization temperature is 30～35 DEG C, makes filtrate circulate knot in cooler crystallizer Brilliant process, it is thus achieved that filter cake be ammonium dihydrogen phosphate product, the component content in detection filtrate；

2) in filtrate, add potassium hydroxide solution and phosphoric acid solution, adjust middle pH value and nitrogen, phosphorus, the potassium content of filtrate, work as filter Liquid, pH value is 3.5～4, and the content of nitrogen component is 20-25%, phosphorus composition content is 4-8%, potassium component content is 10-15% Time, stopping adding potassium hydroxide solution and phosphoric acid solution, add formalin the most in the solution, temperature rises to 50～65 DEG C, Stirring reaction 2.5～4h；

3) in filtrate, calcium, the moderate-element of magnesium and Borax, zinc sulfate, manganese sulfate, the trace compound of cobalt nitrate are added, Stirring reaction 1～1.5h；

4) by step 3) in the solution that obtains be cooled to 15～20 DEG C, carry out crystallization treatment, obtain compound state compound fertilizer just finished product, Described compound state compound fertilizer just finished product containsThe potassium phosphate compound fertilizer of root；

5) compound state compound fertilizer just finished product is carried out pelletize, then dry in the environment of 45～55 DEG C and make Radix Betae special fertilizer.

A kind of production method preparing ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, it is characterised in that: What phosphoric acid mixed with phosphoamide is (1.2-1.5) according to mol ratio: 1.

A kind of production method preparing ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, it is characterised in that: The intermediate of described addition and the mol ratio of ammonia are 1:(1.2～1.4).

A kind of production method preparing ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, it is characterised in that: The concentration of described potassium hydroxide solution is 10～15%.

A kind of production method preparing ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, it is characterised in that: The concentration of described phosphoric acid solution is 10～15%.

A kind of production method preparing ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, it is characterised in that: Described crystallization treatment is: when the content of the nitrogen component in compound state compound fertilizer just finished product be 18-23%, phosphorus composition content be 3- 6%, when potassium component content is 8-13%, crystallization is stopped.

A kind of production method preparing ammonium dihydrogen phosphate by-product Radix Betae special fertilizer, it is characterised in that: Described compound state compound fertilizer just finished product rich in

Realizing controlled-release fertile, whereinWith's Mol ratio is 1:(2～4).