CN118834111A - Water-soluble suspended compound fertilizer prepared from raffinate acid and preparation method thereof - Google Patents

Abstract

The present invention discloses a water-soluble suspended compound fertilizer prepared by using raffinate acid and a preparation method thereof, and belongs to the technical field of compound fertilizers. During the preparation, the raffinate acid is first subjected to pretreatments such as oxidation and addition of a synergist, and then a chelating agent is added to the pretreated raffinate acid, and then ammonium fertilizer, nitrogen fertilizer and a thickener are added, and finally emulsification shearing and sand milling are performed to obtain the compound fertilizer. The present invention can significantly improve the water solubility of metal ions in the raffinate acid by pretreatments such as oxidation and addition of a complex to the raffinate acid, and the final obtained compound fertilizer has excellent water solubility, and a fully water-soluble suspended compound fertilizer can be obtained. At the same time, the present invention uses raffinate acid as a raw material to prepare the compound fertilizer, thereby achieving the purpose of recycling the raffinate acid and effectively solving the environmental pollution problem caused by the raffinate acid.

Description

A water-soluble suspended compound fertilizer prepared by using raffinate acid and preparation method thereof

Technical Field

The invention belongs to the technical field of compound fertilizers, and in particular relates to a water-soluble suspended compound fertilizer prepared by utilizing raffinate acid and a preparation method thereof.

Background Art

Wet-process phosphoric acid is an important intermediate raw material in the phosphorus chemical industry chain. However, due to the high content of metal ions in wet-process phosphoric acid, it cannot be well utilized in the fields of high-concentration fertilizers and fine chemicals. In order to reduce the metal ion content in wet-process phosphoric acid and increase the phosphorus concentration, wet-process phosphoric acid purification technology has been widely used.

Wet-process phosphoric acid purification technology includes solvent extraction, solvent precipitation, chemical precipitation, ion exchange and other methods. Among them, solvent extraction uses the characteristic that phosphoric acid can be dissolved in organic solvents to separate phosphoric acid from impurities to achieve the purpose of purifying phosphoric acid. Similarly, solvent extraction is the most mature and widely used method for industrial wet-process phosphoric acid purification. The phosphoric acid produced by solvent extraction in many countries has reached industrial and food grade standards.

However, it is inevitable that during the production of phosphoric acid using solvent extraction, slag acid containing a large amount of solid phase or raffinate acid containing a large amount of metal ion impurities will be produced. Generally speaking, for every ton of refined phosphoric acid produced, 1 ton of raffinate acid is produced. At present, the annual output of raffinate acid is 1 to 2 million tons, and this figure is increasing significantly every year.

With the development of society, the country has paid more and more attention to environmental issues. As a byproduct that is difficult to utilize during the purification of wet phosphoric acid, many methods of recycling have been developed. First of all, the prior art discloses a variety of purification methods for raffinate acid, such as complex purification method, acid-base adjustment purification method, membrane filtration purification method, etc. At the same time, many methods for directly preparing agricultural fertilizer products using raffinate acid have also been developed, such as preparing monoammonium phosphate, preparing fertilizer-grade diammonium phosphate, preparing superphosphate and heavy superphosphate, ordinary microparticulate fertilizer, etc. However, the economic cost and processing volume of the purification method are difficult to pass, and ordinary agricultural fertilizer products appear to be monotonous and boring, requiring the emergence of more innovative products.

Compared with ordinary agricultural fertilizer products, the water-fertilizer integrated system with water-soluble fertilizer and drip irrigation device has an overwhelming utilization rate advantage. Generally speaking, the utilization rate of ordinary agricultural fertilizer products is about 30%, while the utilization rate of water-fertilizer integrated system is above 70%. Suspended fertilizer is a kind of water-soluble fertilizer. Due to its high nutrient concentration, low water content, and full water solubility, it is currently a hot direction for the development of innovative fertilizers. Generally speaking, due to its high metal ion content, it is difficult to prepare a fully water-soluble product of raffinate acid, and it cannot be used with a drip irrigation device.

Summary of the invention

In view of the above-mentioned prior art, the present invention provides a water-soluble suspended compound fertilizer prepared by using raffinate acid and a preparation method thereof, so as to solve the technical problem that the water-soluble fertilizer prepared by using raffinate acid has poor water solubility.

In order to achieve the above object, the technical solution adopted by the present invention is to provide a method for preparing a water-soluble suspended compound fertilizer using raffinate acid, comprising the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: treating the raffinate so that the content of phosphorus pentoxide is 20-40wt%;

S2: The treated raffinate acid is heated to 40-50°C, and then ozone is introduced into the raffinate acid at a flow rate of 2-5 L/min for 10-20 min;

S3: maintaining the temperature of the treated raffinate at 40-50°C, then adding a synergist to the raffinate and stirring for 10-20 minutes to obtain a pretreated raffinate; the synergist is amino acid, humic acid, alginic acid or sugar;

(2) adding a chelating agent to the pretreated raffinate and mixing well to obtain a base solution;

(3) adding ammonium fertilizer and nitrogen fertilizer to the base solution so that NP ₂ O ₅ -K ₂ O is between 15-15-0 and 20-50-0 to obtain a primary product;

(4) adding a thickener to the primary product, and then sequentially performing emulsification shearing and sand grinding to obtain a water-soluble suspended compound fertilizer; the amount of the thickener added is 0.01-2% of the quality of the primary product.

The beneficial effects of the present invention adopting the above technical solution are:

When the raffinate acid is pretreated, the raffinate acid is first heated. The temperature increase can increase the activity of metal ions in the raffinate acid, and in the subsequent process of introducing ozone and mixing with the ligand, the metal ions are more easily oxidized by ozone and more easily coordinated with the ligand. When ozone is introduced into the raffinate acid, low-valent metal ions such as Fe ²⁺ and Mn ²⁺ in the raffinate acid can be oxidized into high-valent metal ions. The high-valent metal ions have a higher charge density and can form stronger electrostatic attraction and coordination bonds with the coordinating atoms in the synergist. In addition, the high-valent metal ions have a more complex electronic configuration and a larger ionic radius, which can form stable complexes with the synergist.

The synergist in the present invention is amino acid, humic acid, alginic acid or sugar, which is rich in hydrophilic groups such as carboxyl and hydroxyl groups, and can not only form a complex with a stable coordination bond with the metal ions in the raffinate, but also make the complex have more active sites. After the subsequent addition of a chelating agent, it can form a stable chelate with the complex. The groups possessed by the chelate itself and the groups on the ligand have excellent hydrophilic properties and can interact strongly with water molecules, thereby significantly enhancing the solubility of metal ions in water.

Based on the above technical solution, the present invention can also be improved as follows.

Furthermore, the content of phosphorus pentoxide in the raffinate is 5-55wt%; and the treatment is concentration or dilution.

Furthermore, the final temperature of the raffinate in S2 was 45°C; the flow rate of ozone was 3 L/min, and the duration was 15 min.

Furthermore, the liquid ratio of the synergist added in S3 to the raffinate acid is 0.1-10 g:100 mL.

Furthermore, the chelating agent is at least one of the self-made chelating agent prepared in the CN 109928806A patent, EDTA and citric acid.

Furthermore, the amount of the chelating agent added is 0.1-10% of the mass of the pretreated raffinate acid.

Furthermore, the ammonium fertilizer is monoammonium phosphate and the nitrogen fertilizer is urea.

Furthermore, the thickener is xanthan gum, carboxymethyl cellulose or quaternary ammonium salt.

Furthermore, the shear rate of the emulsified shear is 2000-12000 rpm, and the shear time is 10-100 min; the sand grinding is carried out in a sand mill, and the sand grinding time is 10-100 min.

The invention also discloses a water-soluble suspended compound fertilizer prepared by the preparation method.

The beneficial effects of the present invention are:

1. The present invention can significantly improve the water solubility of metal ions in the raffinate by pre-treating the raffinate with oxidation and adding synergists, and the final obtained compound fertilizer has excellent water solubility, and a fully water-soluble suspended compound fertilizer can be obtained.

2. The present invention uses raffinate as a raw material to prepare compound fertilizer, thereby achieving the purpose of recycling raffinate and effectively solving the environmental pollution problem caused by raffinate.

3. The preparation process of the present invention is simple and convenient for large-scale industrial production.

DETAILED DESCRIPTION

The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

Example 1

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: Take the residual acid after producing phosphoric acid in a phosphide chemical plant, in which the content of phosphorus pentoxide is about 18wt%, and then concentrate it to the content of phosphorus pentoxide of 30wt% under the condition of 80℃ water bath;

S2: The raffinate treated by S1 is heated to 45°C, and then ozone is introduced into the raffinate at a flow rate of 3 L/min for 15 min;

S3: maintaining the temperature of the treated raffinate at 45° C., then adding gluconic acid to the raffinate at a solid-liquid ratio of 5 g:100 mL, stirring for 15 min, and obtaining pretreated raffinate;

(2) adding ethylenediaminetetraacetic acid to the pretreated raffinate acid and mixing well to obtain a base liquid; the amount of ethylenediaminetetraacetic acid added is 5% of the mass of the pretreated raffinate acid;

(3) adding monoammonium phosphate and urea to the base liquid to make NP ₂ O ₅ -K ₂ O 15-30-0 to obtain a primary product;

(4) adding 1% carboxymethyl cellulose by weight of the primary product to the primary product, and then emulsifying and shearing the primary product at a shear rate of 10000 rpm for 60 min; then transferring the emulsified and sheared material into a sand mill for sand grinding for 60 min to obtain a water-soluble suspended compound fertilizer.

Example 2

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: taking the residual acid after phosphoric acid is produced in a phosphate chemical plant, wherein the content of phosphorus pentoxide is about 50wt%, and then diluting it by adding water to a content of phosphorus pentoxide of 40wt%;

S2: The raffinate acid treated by S1 is heated to 50°C, and then ozone is introduced into the raffinate acid at a flow rate of 2 L/min for 20 min;

S3: maintaining the temperature of the treated raffinate at 50° C., then adding humic acid to the raffinate at a solid-liquid ratio of 0.1:100 mL, stirring for 20 minutes, and obtaining pretreated raffinate;

(2) adding citric acid to the pretreated raffinate acid and mixing well to obtain a base solution; the amount of citric acid added is 1% of the mass of the pretreated raffinate acid;

(3) adding monoammonium phosphate and urea to the base liquid to make NP ₂ O ₅ -K ₂ O 20-50-0 to obtain a primary product;

(4) adding 0.01% xanthan gum by weight of the primary product to the primary product, and then emulsifying and shearing the primary product at a shear rate of 12000 rpm for 10 min; then transferring the emulsified and sheared material into a sand mill for sand grinding for 100 min to obtain a water-soluble suspended compound fertilizer.

Example 3

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: Take the residual acid after phosphoric acid is produced in a phosphide chemical plant, in which the content of phosphorus pentoxide is about 5wt%, and then concentrate it to a phosphorus pentoxide content of 20wt% under 70℃ water bath conditions;

S2: The raffinate acid treated by S1 is heated to 40°C, and then ozone is introduced into the raffinate acid at a flow rate of 5 L/min for 10 min;

S3: maintaining the temperature of the treated raffinate at 40° C., then adding alginic acid to the raffinate at a solid-liquid ratio of 10 g:100 mL, stirring for 20 min, and obtaining pretreated raffinate;

(2) adding ethylenediaminetetraacetic acid to the pretreated raffinate acid and mixing well to obtain a base solution; the amount of ethylenediaminetetraacetic acid added is 10% of the mass of the pretreated raffinate acid;

(3) adding monoammonium phosphate and urea to the base liquid to make NP ₂ O ₅ -K ₂ O 15-15-0 to obtain a primary product;

(4) adding 2% of the mass of the primary product to the primary product, and then emulsifying and shearing the primary product at a shear rate of 2000 rpm for 100 min; then transferring the emulsified and sheared material into a sand mill for sand grinding for 10 min to obtain a water-soluble suspended compound fertilizer.

Comparative Example 1

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: Take the residual acid after producing phosphoric acid in a phosphide chemical plant, in which the content of phosphorus pentoxide is about 18wt%, and then concentrate it to the content of phosphorus pentoxide of 30wt% under the condition of 80℃ water bath;

S2: The raffinate acid treated by S1 is heated to 45°C, and then ozone is introduced into the raffinate acid at a flow rate of 3 L/min for 15 min to obtain pretreated raffinate acid;

(2) adding humic acid to the pretreated raffinate, mixing well, and obtaining a base solution; the amount of humic acid added is 5% of the mass of the pretreated raffinate;

(3) adding monoammonium phosphate and urea to the base liquid to make NP ₂ O ₅ -K ₂ O 15-30-0 to obtain a primary product;

(4) emulsifying and shearing the primary product at a shear rate of 10000 rpm for 60 min; then transferring the emulsified and sheared material into a sand mill for sand grinding for 60 min to obtain a water-soluble suspended compound fertilizer.

Comparative Example 2

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: Take the residual acid after producing phosphoric acid in a phosphide chemical plant, in which the content of phosphorus pentoxide is about 18wt%, and then concentrate it to the content of phosphorus pentoxide of 30wt% under the condition of 80℃ water bath;

S2: The raffinate treated by S1 is heated to 45°C, and then gluconic acid is added to the raffinate at a solid-liquid ratio of 4 g:10 mL, and stirred for 15 min to obtain pretreated raffinate;

(2) adding humic acid to the pretreated raffinate, mixing well, and obtaining a base solution; the amount of humic acid added is 5% of the mass of the pretreated raffinate;

(3) adding monoammonium phosphate and urea to the base liquid to make NP ₂ O ₅ -K ₂ O 15-30-0 to obtain a primary product;

(4) emulsifying and shearing the primary product at a shear rate of 10000 rpm for 60 min; then transferring the emulsified and sheared material into a sand mill for sand grinding for 60 min to obtain a water-soluble suspended compound fertilizer.

Comparative Example 3

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) The raffinate acid after phosphoric acid production in a phosphate chemical plant, in which the content of phosphorus pentoxide is about 18wt%, is then concentrated to a phosphorus pentoxide content of 30wt% in a water bath at 80°C;

(2) adding humic acid to the raffinate treated in step (1), mixing well, and obtaining a base liquid; the amount of humic acid added is 5% of the mass of the raffinate;

(3) adding monoammonium phosphate and urea to the base liquid to make NP ₂ O ₅ -K ₂ O 15-30-0 to obtain a primary product;

(4) emulsifying and shearing the primary product at a shear rate of 10000 rpm for 60 min; then transferring the emulsified and sheared material into a sand mill for sand grinding for 60 min to obtain a water-soluble suspended compound fertilizer.

Comparative Example 4

A water-soluble suspended compound fertilizer prepared by using raffinate acid, the preparation method of which comprises the following steps:

(1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps:

S1: Take the residual acid after producing phosphoric acid in a phosphide chemical plant, in which the content of phosphorus pentoxide is about 18wt%, and then concentrate it to the content of phosphorus pentoxide of 30wt% under the condition of 80℃ water bath;

S2: The raffinate treated by S1 is heated to 45°C, and then ozone is introduced into the raffinate at a flow rate of 3 L/min for 15 min;

S3: maintaining the temperature of the treated raffinate at 45° C., then adding gluconic acid to the raffinate at a solid-liquid ratio of 4 g:10 mL, and stirring for 15 min to obtain pretreated raffinate;

(2) adding monoammonium phosphate and urea to the pretreated raffinate to make NP ₂ O ₅ -K ₂ O 15-30-0 to obtain a primary product;

(3) The primary product is emulsified and sheared at a shear rate of 10000 rpm for 60 min; the emulsified and sheared material is then transferred into a sand mill for sand grinding for 60 min to obtain a water-soluble suspended compound fertilizer.

Experimental example

1. Turbidity and pH test

The turbidity of the water-soluble suspended compound fertilizer prepared by using raffinate in the above-mentioned embodiments and comparative examples after dilution by 0 times, 50 times, 100 times and 160 times was tested by spectrophotometry, and the pH value of the water-soluble suspended compound fertilizer after dilution by 0 times, 50 times, 100 times and 160 times was measured. The results are shown in Table 1.

Table 1 Turbidity and pH value of water-soluble suspended compound fertilizer

As can be seen from Table 1, the water-soluble suspended compound fertilizer prepared by the preparation method in the embodiment has a lower initial pH value and a lower initial turbidity. After dilution, the pH value does not increase significantly, but the turbidity does drop significantly, especially after dilution 160 times, the turbidity drops to below 50NTU; the low pH value indicates that the water-soluble suspended compound fertilizer in the embodiment is easily dissolved in hard water, does not produce precipitation during use, and can effectively avoid the problem of clogging the drip irrigation device. The rapid change of turbidity indicates that the water-soluble suspended compound fertilizer in the embodiment has excellent water-solubility, exhibits full water-solubility, can be directly used for fertilization using a drip irrigation device, and will not have adverse effects on the drip irrigation system.

2. Thixotropic ring area test

The thixotropic ring area of the water-soluble suspended compound fertilizer prepared by using raffinate acid in the above-mentioned embodiments and comparative examples was tested by using a variable speed viscometer. The maximum detection rate of the test was 50 s ^-1 . The results are shown in Table 2.

Table 2 Thixotropic ring area of water-soluble suspended compound fertilizer

It can be seen from Table 2 that the water-soluble suspended compound fertilizer prepared by the preparation method in the embodiment has a large thixotropic ring area, indicating that the water-soluble suspended compound fertilizer in the embodiment has excellent suspension performance and can effectively reduce the risk of precipitation and blockage when used in conjunction with the drip irrigation system.

Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims (10)

1. A method for preparing a water-soluble suspended compound fertilizer using raffinate, characterized in that it comprises the following steps: (1) pretreating the raffinate to obtain pretreated raffinate; the pretreating of the raffinate comprises the following steps: S1: treating the raffinate so that the content of phosphorus pentoxide is 20-40wt%; S2: The treated raffinate acid is heated to 40-50°C, and then ozone is introduced into the raffinate acid at a flow rate of 2-5 L/min for 10-20 min; S3: maintaining the temperature of the treated raffinate at 40-50° C., then adding a synergist to the raffinate and stirring for 10-20 minutes to obtain a pretreated raffinate; the synergist is amino acid, humic acid, alginic acid or sugar; (2) adding a chelating agent to the pretreated raffinate and mixing well to obtain a base solution; (3) adding ammonium fertilizer and nitrogen fertilizer to the base solution so that NP ₂ O ₅ -K ₂ O is between 15-15-0 and 20-50-0 to obtain a primary product; (4) adding a thickener to the primary product, and then sequentially performing emulsification shearing and sand grinding to obtain a water-soluble suspended compound fertilizer; the amount of the thickener added is 0.01-2% of the quality of the primary product. 2. The method for preparing a water-soluble suspended compound fertilizer using raffinate according to claim 1, characterized in that: the content of phosphorus pentoxide in the raffinate is 5-55wt%; and the treatment is concentration or dilution. 3. The method for preparing water-soluble suspended compound fertilizer using raffinate according to claim 1, characterized in that: the final temperature of the raffinate in S2 is 45°C; the flow rate of ozone is 3L/min, and the duration is 15min. 4. The method for preparing a water-soluble suspended compound fertilizer by utilizing raffinate acid according to claim 1, characterized in that the solid-liquid ratio of the synergist added in S3 to the raffinate acid is 0.1-10 g:100 mL. 5. The method for preparing water-soluble suspended compound fertilizer using raffinate according to claim 1, wherein the chelating agent is at least one of EDTA and citric acid. 6. The method for preparing water-soluble suspended compound fertilizer using raffinate according to claim 5, characterized in that the amount of the chelating agent added is 0.1-10% of the mass of the pretreated raffinate. 7. The method for preparing a water-soluble suspended compound fertilizer using raffinate according to claim 1, wherein the ammonium fertilizer is monoammonium phosphate and the nitrogen fertilizer is urea. 8. The method for preparing water-soluble suspended compound fertilizer using raffinate according to claim 1, wherein the thickener is xanthan gum, carboxymethyl cellulose or quaternary ammonium salt. 9. The method for preparing a water-soluble suspended compound fertilizer by utilizing raffinate according to claim 1, characterized in that: the shear rate of the emulsified shearing is 2000-12000 rpm, and the shearing time is 10-100 min; the sand grinding is performed in a sand mill, and the sand grinding time is 10-100 min. 10. A water-soluble suspended compound fertilizer, characterized in that it is prepared by the method for preparing a water-soluble suspended compound fertilizer by using raffinate acid as described in any one of claims 1 to 9.