CN104326456A - Method for preparation of sodium dihydrogen phosphate and coproduction of special compound fertilizer for loquat - Google Patents

Abstract

The invention discloses a method for preparing a special compound fertilizer for loquats co-produced by sodium dihydrogen phosphate. The method comprises the following three steps: reacting to prepare an intermediate, preparing sodium dihydrogen phosphate, and preparing a special compound fertilizer for loquats. Through the control of raw materials, temperature, and element content, the filtrate that can be prepared as a special compound fertilizer for loquat is obtained. The compound fertilizer prepared by using this filtrate can not only meet the needs of loquat for nutrient elements, but also will not appear due to residual fertilizer. The problem of soil environmental pollution has a high environmental value and economic value.

Description

A kind of method for preparing loquat special-purpose compound fertilizer co-production of sodium dihydrogen phosphate

technical field

The invention relates to the technical field of chemical fertilizers, in particular to a method for preparing a special compound fertilizer for co-production of loquat with sodium dihydrogen phosphate. the

Background technique

Loquat is also known as Luju, Luzhi, Jinwan, Yanguo, Jiaozi, Rosaceae, and Loquat. Loquat is native to southeastern my country. It is named for its leaves shaped like a lute. Its flowers can be used as medicine. The height of the tree is 3-5 meters, the leaves are large and long, thick and hairy, oblong, and shaped like a lute. Unlike most fruit trees, loquat blooms in autumn or early winter, and its fruit matures in spring to early summer, earlier than other fruits. Therefore, it is called "the one with the unique spirit of the four seasons among fruit trees". The flower of loquat is white or light yellow, has five petals, about 2 centimeters in diameter, forms a bunch with five to ten, can be used as nectar crop. Loquat likes light, slightly shade-tolerant, likes warm climate and fertile, moist, well-drained soil, slightly cold-resistant, not cold-tolerant, slow growth, average temperature above 12-15°C, not lower than -5°C in winter, flowering stage, young fruit stage is not low It can grow well in the area of 0 ℃. The growth of loquat is inseparable from fertilizers, and after ordinary fertilizers are applied to cultivated land, part of them will be transpired, dissipated and lost with water, part of them will be fixed and utilized by soil and soil microorganisms, and only part of them will be absorbed and utilized by crops. Studies have shown that: the utilization rate of urea and ammonium bicarbonate is 20%-46%, phosphate fertilizer (diammonium, monoammonium, heavy calcium) is 10%-25%, and potassium fertilizer is 45%-60%. It can be seen that the utilization rate of ordinary fertilizers is very low. For this reason, the present inventor has studied a kind of method for preparing the special fertilizer of loquat for the characteristic of loquat and the characteristic of liking fertilizer, needs to absorb more nutritive substance in a growth cycle of loquat, not only nitrogen, phosphorus, nitrogen that common fertilizer provides, If potassium is lacking in other nutrients, it will not grow normally, the plants will be thin and small, the headings will be uneven, and the pollination rate will be low, which will seriously affect the yield. The present invention is a complex containing multiple nutrients, not a chemical fertilizer with a single nutrient. In addition to nitrogen, phosphorus, potassium and other macronutrient elements, it is also rich in elements necessary for crops such as sodium, calcium, magnesium, etc., which plays a role in regulating The role of soil balance nutrition is a new type of high-efficiency green full-nutrient chelation special fertilizer. The special fertilizer is prepared according to the normal growth and development of loquat, cultivation characteristics, irrigation habits, and nutrient elements needed. Add a variety of nutritional elements to protect the health of loquats, make their fertility more durable, effectively regulate the resistance of plant organisms, reduce diseases, and increase yields. Greatly improve the quality of crops, improve the immunity of loquat itself, and can well prevent the common disease of loquat. the

Sodium dihydrogen phosphate is the raw material for manufacturing sodium hexametaphosphate and sodium pyrophosphate, mainly used in tanning, boiler water treatment, as a quality improver and baking powder, and as a buffer and fermentation powder in the food industry and fermentation industry Raw materials, also used as feed additives, detergents and dyeing auxiliaries. the

The patent document that publication number is CN101475463A discloses a kind of method that calcium formate and superphosphoric acid react and co-produce high-purity formic acid and sodium dihydrogen phosphate, this method adopts carbon monoxide to enter reaction three towers, potassium hydroxide enters reaction one tower, and comes from The carbon monoxide in the second reaction tower reacts countercurrently, the reaction liquid overflows to the second reaction tower, and reacts countercurrently with the carbon monoxide gas from the third reaction tower. The feed tank is used to prepare a calcium formate preparation solution. The calcium formate preparation solution enters the reactor, drips formic acid, feeds hydrogen sulfide, and separates the filter residue through the filter I. The filtrate enters the continuous crystallizer, and the crystallization solution enters the filter II. The calcium formate is made into finished calcium formate through the dryer, superphosphoric acid, formic acid and calcium formate are input into the horizontal twin-screw reactor to generate formic acid and calcium dihydrogen phosphate, which enter the formic acid distillation tank for vacuum distillation, and the calcium dihydrogen phosphate is transported to Calcium dihydrogen phosphate metering receiving tank, formic acid enters the formic acid receiving tank, although the formic acid prepared by this method has high purity, but due to the complicated preparation process, high equipment requirements, and the unstable sodium dihydrogen phosphate product, the production cost is too high . the

The present inventor has proposed a kind of method that can prepare high-purity sodium dihydrogen phosphate and co-produce loquat special-purpose compound fertilizer simultaneously by the repeated research and experiment to preparation sodium dihydrogen phosphate technology and document, has fully utilized resource, has reduced cost. the

Contents of the invention

In order to solve the above-mentioned technical problems, the invention provides a kind of preparation method of the compound fertilizer specially used for co-production of loquat with sodium dihydrogen phosphate, which has the advantages of low environmental pollution, low equipment requirements, low production cost, high purity of sodium dihydrogen phosphate product, etc. Moreover, the by-product special compound fertilizer for loquat can be fully absorbed by the loquat, and the compound fertilizer has a proper combination of nutritional elements and has certain environmental protection value and economic value. the

The present invention is achieved through the following technical solutions:

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

(a) Preparation of intermediate by reaction: Mix urea and phosphoric acid in a molar ratio of 2:2.4-2.9, raise the temperature to 111-119°C, stir and react at a stirring speed of 70-80r/min for 2.2h, and separate to obtain the intermediate;

(b) Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.2-3.7, react for 80-98min to obtain a mother liquor containing nitrogen, phosphorus and sodium, and place the mother liquor in a cooling crystallizer Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.2-15.7%, the phosphorus pentoxide content is 7.2-7.7%, and the sodium content is 4.2-4.7%, stop crystallization and filter, and the obtained filter cake is Sodium dihydrogen phosphate;

(c) Preparation of special compound fertilizer for loquat: add the elements required for loquat to the obtained filtrate, and take the heating rate of 3°C/min to heat up the filtrate to 24°C for drying. After drying for 30min, when the water content is 4.5% , to obtain the finished loquat special compound fertilizer. the

The intermediate separated in the step a is urea phosphate. the

The reaction of urea and phosphoric acid in the step a is the reaction of urea solid and phosphoric acid solution. the

The concentration of phosphoric acid in the step a is 65-70%. the

The reaction of intermediate and sodium hydroxide is the reaction of the sodium hydroxide solution obtained after intermediate solid and sodium hydroxide dissolve in the described step b. the

The cooling temperature of cooling crystallization in the step b is 19-24°C. the

The required elements of loquat in the step c are potassium, calcium and magnesium. the

The special compound fertilizer for loquat in the step c is a compound fertilizer in a compound state, and its composition contains the following structural formula of nitrogen, phosphorus and potassium in a compound state:

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.

The beneficial effect of the present invention is that: sodium dihydrogen phosphate is prepared by reacting phosphoric acid with urea, the preparation process is simple, the requirements for production equipment are low, there is no pollution in the whole production process, no waste water and waste gas discharge, low energy consumption, and the produced dihydrogen phosphate The sodium product is stable and has high purity, which reduces the production cost, and in the process of preparing sodium dihydrogen phosphate, through the control of raw materials, temperature, and element content, a filtrate that can be prepared as a special compound fertilizer for loquat is obtained, and the filtrate is used The prepared compound fertilizer can not only meet the demand of loquat for nutrient elements, but also avoid the problem of soil environmental pollution caused by residual fertilizer, and has high environmental protection value and economic value. the

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the examples, but the scope of protection is not limited to the description. the

Description of the reaction principle:

Urea reacts with phosphoric acid to form urea phosphate. Urea phosphate will form a kind of ionic double salt with positive and negative charges attracted by phosphoric acid and high temperature environment. In the presence of phosphoric acid, urea phosphate ion double salt will form H ₂ NCONH ₃ The ⁺ ion is close to phosphoric acid, forming the intermediate ion of the C→O coordination bond, that is, the CO ₅ PN ₂ H ₈ ⁺ ion, which makes the urea phosphate intermediate contain a large amount of H ₂ PO ₄ ^- and CO ₅ PN ₂ H ₈ ⁺ ions, when adding an appropriate amount of sodium ions, dihydrogen phosphate and sodium ions form sodium dihydrogen phosphate crystals to be precipitated, then add potassium ions to react with CO ₅ PN ₂ H ₈ ⁺ ions, and replace part of NH4+, making The solution contains double salt ions of CO ₅ PNH ₄ K ⁺ , and the compound fertilizer can be obtained by adjusting the elements and finally drying the filtrate. Concrete reaction equation is as follows:

Reaction equation one:

H ₂ PO ₃ +CO(NH ₂ ) ₂ —CO(NH ₂ ) ₂ ·H ₃ PO ₄

Reaction equation two:

CO(NH ₂ ) ₂ ·H ₃ PO ₄ —H ₂ NCONH ₃ ⁺ +H ₂ PO ₄ ^-

Reaction equation three:

H ₂ PO ₄ ^- +Na ⁺ —NaH ₂ PO ₄

Reaction equation four:

Reaction equation five:

The present invention will be further elaborated below in conjunction with embodiment:

Example 1

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

a. Preparation of intermediate by reaction: Mix urea and phosphoric acid with a concentration of 65% in a molar ratio of 2:2.4, raise the temperature to 111°C, stir and react for 2.2 hours at a stirring speed of 70r/min, and separate to obtain the intermediate;

b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.2, and obtain a mother liquor containing nitrogen, phosphorus, and sodium after reacting for 80 minutes, and place the mother liquor in a cooling crystallizer to control the temperature at 19°C Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.2%, phosphorus pentoxide content is 7.2%, and sodium content is 4.2%, stop crystallization and filter, and the obtained filter cake is sodium dihydrogen phosphate;

c. Preparation of special compound fertilizer for loquat: add potassium, calcium and magnesium elements required by loquat to the obtained filtrate, and take the temperature increase rate of 3°C/min to raise the temperature of the filtrate to 24°C for drying. After drying for 30min, when the water content When it is 4.5%, the finished product of special compound fertilizer for loquat is obtained. the

Example 2

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

a. Preparation of intermediate by reaction: Mix urea and phosphoric acid with a concentration of 66% in a molar ratio of 2:2.5, raise the temperature to 112°C, stir and react at a stirring speed of 71r/min for 2.2h, and separate to obtain the intermediate;

b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.3, and obtain a mother liquor containing nitrogen, phosphorus, and sodium after reacting for 82 minutes, and place the mother liquor in a cooling crystallizer to control the temperature at 20°C Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.3%, the phosphorus pentoxide content is 7.3%, and the sodium content is 4.3%, stop crystallization and filter, and the obtained filter cake is sodium dihydrogen phosphate;

c. Preparation of special compound fertilizer for loquat: add potassium, calcium and magnesium elements required by loquat to the obtained filtrate, and take the temperature increase rate of 3°C/min to raise the temperature of the filtrate to 24°C for drying. After drying for 30min, when the water content When it is 4.5%, the finished product of special compound fertilizer for loquat is obtained. the

Example 3

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

a. Preparation of intermediate by reaction: Mix urea and phosphoric acid with a concentration of 67% in a molar ratio of 2:2.6, raise the temperature to 113°C, stir and react at a stirring speed of 73r/min for 2.2h, and separate to obtain the intermediate;

b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.4, and obtain a mother liquor containing nitrogen, phosphorus, and sodium after reacting for 84 minutes, and place the mother liquor in a cooling crystallizer to control the temperature at 21°C Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.4%, the phosphorus pentoxide content is 7.4%, and the sodium content is 4.4%, stop crystallization and filter, and the obtained filter cake is sodium dihydrogen phosphate;

c. Preparation of special compound fertilizer for loquat: add potassium, calcium and magnesium elements required by loquat to the obtained filtrate, and take the temperature increase rate of 3°C/min to raise the temperature of the filtrate to 24°C for drying. After drying for 30min, when the water content When it is 4.5%, the finished product of special compound fertilizer for loquat is obtained. the

Example 4

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

a. Preparation of intermediate by reaction: Mix urea and phosphoric acid with a concentration of 68% in a molar ratio of 2:2.7, raise the temperature to 116°C, stir and react for 2.2 hours at a stirring speed of 75r/min, and separate to obtain the intermediate;

b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.5, and obtain a mother liquor containing nitrogen, phosphorus, and sodium after reacting for 86 minutes, and place the mother liquor in a cooling crystallizer to control the temperature at 22°C Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.5%, phosphorus pentoxide content is 7.5%, and sodium content is 4.5%, stop crystallization and filter, and the obtained filter cake is sodium dihydrogen phosphate;

c. Preparation of special compound fertilizer for loquat: add potassium, calcium and magnesium elements required by loquat to the obtained filtrate, and take the temperature increase rate of 3°C/min to raise the temperature of the filtrate to 24°C for drying. After drying for 30min, when the water content When it is 4.5%, the finished product of special compound fertilizer for loquat is obtained. the

Example 5

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

a. Preparation of intermediate by reaction: Mix urea and phosphoric acid with a concentration of 69% in a molar ratio of 2:2.8, raise the temperature to 118°C, stir and react at a stirring speed of 79r/min for 2.2h, and separate to obtain the intermediate;

b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.6, and obtain a mother liquor containing nitrogen, phosphorus and sodium after reacting for 88 minutes, and place the mother liquor in a cooling crystallizer to control the temperature at 23°C Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.6%, phosphorus pentoxide content is 7.6%, and sodium content is 4.6%, stop crystallization and filter, and the obtained filter cake is sodium dihydrogen phosphate;

c. Preparation of special compound fertilizer for loquat: add potassium, calcium and magnesium elements required by loquat to the obtained filtrate, and take the temperature increase rate of 3°C/min to raise the temperature of the filtrate to 24°C for drying. After drying for 30min, when the water content When it is 4.5%, the finished product of special compound fertilizer for loquat is obtained. the

Example 6

A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, the method comprises the following steps:

a. Preparation of intermediate by reaction: Mix urea and phosphoric acid with a concentration of 70% in a molar ratio of 2:2.9, raise the temperature to 119°C, stir and react at a stirring speed of 80r/min for 2.2h, and separate to obtain the intermediate;

b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.7, and obtain a mother liquor containing nitrogen, phosphorus, and sodium after reacting for 91 minutes, and place the mother liquor in a cooling crystallizer to control the temperature at 24°C Cool down and crystallize, and monitor and analyze the mother liquor at the same time. When the nitrogen content is 15.7%, the phosphorus pentoxide content is 7.7%, and the sodium content is 4.7%, stop crystallization and filter, and the obtained filter cake is sodium dihydrogen phosphate;

c. Preparation of special compound fertilizer for loquat: add potassium, calcium and magnesium elements required by loquat to the obtained filtrate, and take the temperature increase rate of 3°C/min to raise the temperature of the filtrate to 24°C for drying. After drying for 30min, when the water content When it is 4.5%, the finished product of special compound fertilizer for loquat is obtained. the

The products and technical effects of the present invention will be further described below in conjunction with specific experimental examples. the

Experimental example 1

Embodiment 1 of the present invention, embodiment 2, embodiment 3, embodiment 4, embodiment 5, embodiment 6, the compound fertilizer special for loquat prepared in the present invention detects according to GB1887-2002 standard, and its result is as shown in table 1:

Table 1 The element content detection of the special compound fertilizer for loquat of the present invention

Test items Eligibility criteria Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 NPK 30% 30.4% 30.6% 30.8% 31% 31.2% 31.4% nitrogen 15% 15.2% 15.3% 15.4% 15.5% 15.6% 15.7% phosphorus 7% 7.2% 7.3% 7.4% 7.5% 7.6% 7.7% Potassium 8% 8% 8% 8% 8% 8% 8%

[0070] water content ≤10% 4.5% 4.5% 4.5% 4.5% 4.5% 4.5%

Can know that the elemental content of the special compound fertilizer for loquat prepared by the present invention has not only reached qualified standard, but is far superior to qualified standard from table 1, illustrates that this compound fertilizer can satisfy the nutrient element demand of loquat, has remarkable effect on technical effect progress. the

Experimental example 2

Embodiment 1 of the present invention, embodiment 2, embodiment 3, embodiment 4, embodiment 5, embodiment 6, the sodium dihydrogen phosphate product prepared in the embodiment is detected by the detection method of GB25564-2010. the

Table 2 The purity detection of sodium dihydrogen phosphate product of the present invention

As can be seen from Table 2, the sodium dihydrogen phosphate produced by the technical solution of the present invention has not only reached the qualified standard, but also the purity of the product is higher, indicating that the method prepares the sodium dihydrogen phosphate product has significant progress. the

Experimental example 3

According to the absorption of element content and the yield of loquat trees, a comparative experiment was carried out between the special compound fertilizer for loquat and the common fertilizer. Take 9 loquat trees as the experimental objects, respectively labeled as A, B, C, D, E, F, G, H, I, apply common fertilizer to the loquat trees with three labels of A, B, and C, and apply common fertilizer to the loquat trees with three labels, D, E , F, G, H, I and other six labels of the loquat fertilizers prepared in embodiment 1, embodiment 2, embodiment 3, embodiment 4, embodiment 5, embodiment 6 respectively, contrast The experimental results are shown in Table 3:

Table 3 Comparison of the element absorption rate of loquat trees and the effect on loquat yield of common fertilizer and loquat special compound fertilizer

As can be seen from the above table, the special compound fertilizer for loquat prepared by the present invention can be fully absorbed by the loquat, and is also rich in nutrients needed by the loquat such as Ca, Me, Na, etc., which provides a guarantee for the normal growth of the loquat and improves the growth of the loquat. , increased the output of loquat, improved economic benefits. the

Claims (8)

1. A method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer, is characterized in that, the method may further comprise the steps: a. Preparation of intermediate by reaction: Mix urea and phosphoric acid in a molar ratio of 2:2.4-2.9, raise the temperature to 111-119°C, stir and react for 2.2 hours at a stirring speed of 70-80r/min, and separate to obtain the intermediate; b. Preparation of sodium dihydrogen phosphate: mix the intermediate with sodium hydroxide, control the pH value to 3.2-3.7, react for 80-98 minutes to obtain a mother liquor containing nitrogen, phosphorus, and sodium, and place the mother liquor in a cooling crystallizer to cool down Crystallization, while monitoring and analyzing the mother liquor, when the nitrogen content is 15.2-15.7%, the phosphorus pentoxide content is 7.2-7.7%, and the sodium content is 4.2-4.7%, stop crystallization and filter, and the obtained filter cake is phosphoric acid Sodium dihydrogen; c, preparation of special compound fertilizer for loquat: add the required elements of loquat to the obtained filtrate, and take the heating rate of 3°C/min to heat up the filtrate to 24°C for drying, after drying for 30min, when the water content is 4.5%, The finished compound fertilizer special for loquat is obtained. the 2. The method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer according to claim 1, characterized in that: the intermediate separated in the step a is urea phosphate. the 3. The method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer according to claim 1, characterized in that: the reaction of urea and phosphoric acid in the step a is the reaction of urea solid and phosphoric acid solution. the 4. The method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer according to claim 1, characterized in that: the concentration of phosphoric acid in the step a is 65-70%. the 5. the method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer according to claim 1, is characterized in that: the reaction of intermediate and sodium hydroxide is after intermediate solid and sodium hydroxide dissolve in the described step b The resulting sodium hydroxide solution was reacted. the 6. The method for preparing the special compound fertilizer for co-production of loquat with sodium dihydrogen phosphate according to claim 1, characterized in that: the cooling temperature of cooling crystallization in the step b is 19-24°C. the 7. The method for preparing loquat special compound fertilizer co-produced by sodium dihydrogen phosphate according to claim 1, characterized in that: the required elements for loquat in the step c are potassium, calcium and magnesium. the 8. the method for preparing sodium dihydrogen phosphate co-production loquat special compound fertilizer according to claim 1, is characterized in that: the loquat special compound fertilizer is compound state compound fertilizer in the described step c, contains following nitrogen and phosphorus in its composition Structural formula of potassium compound state: 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.