阅读说明：本技术 硝酸磷肥及其制备方法 (Nitrophosphate fertilizer and preparation method thereof ) 是由 任光耀 顾春光 方进 张凌云 黄德明 赵国军 于 2018-07-19 设计创作，主要内容包括：本发明涉及一种硝酸磷肥及其制备方法。一种硝酸磷肥的制备方法,包括以下步骤：将硝酸磷肥浓缩料浆熔融,得到熔融料浆；采用蒸汽雾化的方式将熔融料浆在加压的条件下进行喷浆造粒,得到硝酸磷肥。上述硝酸磷肥的制备方法通过采用蒸汽雾化的方式来制备硝酸磷肥,在蒸汽的作用下,能够避免硝酸磷肥料浆堵塞喷头,以提高硝酸磷肥的生产效率,同时,相比干燥空气雾化的方式,蒸汽雾化的方式省去了干燥空气的步骤,简化了生产流程,进一步提高生产效率；相比双轴造粒工艺,喷浆造粒工艺制备得到的硝酸磷肥的光圆度更好。因此,上述硝酸磷肥的制备方法具有生产效率较高的优点,且制备得到的硝酸磷肥的光圆度较好。(The invention relates to nitrophosphate fertilizers and a preparation method thereof. nitrophosphate fertilizers are prepared by melting the concentrated nitrophosphate fertilizer slurry to obtain molten slurry, and performing slurry spraying granulation on the molten slurry in a steam atomization mode under a pressurized condition to obtain the nitrophosphate fertilizers.)

The preparation method of the nitric phosphate fertilizer of 1 and is characterized by comprising the following steps:

melting the concentrated slurry of the nitrophosphate fertilizer to obtain molten slurry;

and (3) carrying out spraying granulation on the molten slurry under a pressurized condition by adopting a steam atomization mode to obtain the nitrophosphate fertilizer.

2. The method for preparing a nitrophosphate fertilizer as claimed in claim 1, characterized in that in the step of performing slurry spraying granulation on the molten slurry under a pressurized condition by adopting a steam atomization mode, the pressure of steam is 0.3 Mpa-2.0 Mpa.

3. The method for preparing a nitrophosphate fertilizer as claimed in claim 1, wherein the step of melting the nitrophosphate fertilizer concentrated slurry is specifically as follows: and heating the concentrated nitrophosphate fertilizer slurry to 125-170 ℃ for melting.

4. The method for preparing a nitrophosphate fertilizer as claimed in claim 1, characterized in that the mass percentage concentration of the nitrophosphate fertilizer concentrated slurry is 95% -99%.

5. The method for preparing a nitrophosphate fertilizer as claimed in claim 1, wherein in the step of performing slurry spraying granulation on the molten slurry in a steam atomization manner under a pressurized condition, the method further comprises a step of adding a return material, wherein the mass ratio of the return material to the molten slurry is 3: 1-5: 1.

6. The method for producing a nitrophosphate fertilizer of claim 1, further comprising a step of producing the nitrophosphate fertilizer concentrated slurry, wherein the step of producing the nitrophosphate fertilizer concentrated slurry comprises:

mixing nitric acid and phosphorite to obtain acidolysis solution;

filtering the acidolysis solution to obtain filtrate;

crystallizing the filtrate to obtain calcium nitrate crystals;

removing the calcium nitrate crystal to obtain clear liquid;

introducing ammonia gas into the clear liquid to obtain a neutralized liquid;

and concentrating the neutralized solution to obtain concentrated slurry of the nitrophosphate fertilizer.

7. The method of claim 6, further comprising polymerizing the concentrated neutralized solution after the step of concentrating the neutralized solution.

8. The method for preparing a nitrophosphate fertilizer according to claim 7, characterized in that in the step of polymerization, the temperature of the polymerization is 175-200 ℃ and the time of the polymerization is 20-60 min.

9. The method for preparing a nitrophosphate fertilizer as claimed in claim 7, characterized in that the rate of polymerization of the nitrophosphate fertilizer concentrated slurry is 3% -13%.

10. The nitrophosphate fertilizer prepared by the method for preparing the nitrophosphate fertilizer of any of claims 1 to 9.

Technical Field

The invention relates to the technical field of nitrophosphate fertilizers, in particular to nitrophosphate fertilizers and a preparation method thereof.

Background

In the technical field of preparation of nitrophosphate fertilizers by a freezing method, the traditional preparation process of the nitrophosphate fertilizers is mainly a biaxial granulation process, but fertilizer particles of the biaxial granulation process are not round; the fertilizer light roundness of the spray granulation is good, and the spray granulation is suitable for the current fertilizer requirements, but a spray head in the spray granulation process is easy to block, so that the production efficiency is reduced.

Disclosure of Invention

Therefore, there is a need for a method for producing types of nitrophosphate fertilizers having high production efficiency and good optical circularity.

In addition, nitrophosphate fertilizers are also provided.

The preparation method of nitrophosphate fertilizer comprises the following steps:

melting the concentrated slurry of the nitrophosphate fertilizer to obtain molten slurry;

and (3) carrying out spraying granulation on the molten slurry under a pressurized condition by adopting a steam atomization mode to obtain the nitrophosphate fertilizer.

According to the preparation method of the nitrophosphate fertilizer, the nitrophosphate fertilizer is prepared in a steam atomization mode, the situation that the nitrophosphate fertilizer slurry blocks a spray head can be avoided under the action of steam, so that the production efficiency of the nitrophosphate fertilizer is improved, meanwhile, compared with a dry air atomization mode, a step of drying air is omitted in the steam atomization mode, the production flow is simplified, the production efficiency is further improved in the step, and compared with a double-shaft granulation process, the photoplethality of the nitrophosphate fertilizer prepared by a slurry spraying granulation process is better.

In examples, the step of spraying and granulating the molten slurry under the condition of pressurization by adopting a steam atomization mode, wherein the pressure of steam is 0.3 MPa-2.0 MPa.

In examples, the step of melting the nitrophosphate fertilizer concentrated slurry is specifically to heat the nitrophosphate fertilizer concentrated slurry to 125-170 ℃ for melting.

In embodiments, the mass percentage concentration of the nitrophosphate fertilizer concentrated slurry is 95-99%.

In examples, the step of performing spray granulation on the molten slurry by adopting a steam atomization mode under a pressurized condition further comprises a step of adding a return material, wherein the mass ratio of the return material to the molten slurry is 3: 1-5: 1.

In embodiments, the method further comprises a step of preparing the nitrophosphate fertilizer concentrated slurry, and the step of preparing the nitrophosphate fertilizer concentrated slurry comprises the following steps:

mixing nitric acid and phosphorite to obtain acidolysis solution;

filtering the acidolysis solution to obtain filtrate;

crystallizing the filtrate to obtain calcium nitrate crystals;

removing the calcium nitrate crystal to obtain clear liquid;

introducing ammonia gas into the clear liquid to obtain a neutralized liquid;

and concentrating the neutralized solution to obtain concentrated slurry of the nitrophosphate fertilizer.

In embodiments, the step of concentrating the neutralized solution further comprises polymerizing the concentrated neutralized solution.

In examples, in the step of polymerization, the temperature of polymerization is 175-200 ℃, and the time of polymerization is 20-60 min.

In examples, the polymerization rate of the nitrophosphate concentrated slurry is 3-13%.

The nitric phosphate fertilizer prepared by the preparation method of the nitric phosphate fertilizer is a nitric phosphate fertilizer.

Drawings

FIG. 1 is a flow chart illustrating a method for producing a nitrophosphate fertilizer according to an embodiment of ;

FIG. 2 is a schematic structural view of a drum according to the embodiment ;

FIG. 3 is a schematic view of an alternative angle of the advance zone of the drum shown in FIG. 2;

FIG. 4 is a schematic view of another angle of the lifting area of the drum shown in FIG. 2;

fig. 5 is a schematic view of another angle of the cooling zone of the drum shown in fig. 2.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Referring to fig. 1, a method for preparing a nitrophosphate fertilizer according to the embodiment of includes the following steps:

step S110: and melting the concentrated nitrophosphate slurry to obtain molten slurry.

Wherein the mass percentage concentration of the nitrophosphate concentrated slurry is 95-99%.

The method specifically comprises the following steps of melting concentrated nitrophosphate slurry: heating the concentrated slurry of the nitrophosphate fertilizer to 125-170 ℃ for melting. The water in the concentrated slurry of the nitrophosphate can be removed by melting the concentrated slurry of the nitrophosphate, so that the nitrophosphate prepared has less water content and higher stability.

The nitrophosphate concentrated slurry comprises the following preparation steps:

step S111: mixing nitric acid and phosphorite to obtain acidolysis solution.

Step S112: filtering the acidolysis solution to obtain filtrate.

Wherein in the step of filtering the acidolysis solution, the filtering equipment is at least selected from a vortex screw machine, a washing drum and a plate-and-frame filter press.

Step S113: crystallizing the filtrate to obtain calcium nitrate crystals.

Wherein, the method for crystallizing the filtrate is freezing crystallization. Generally, the calcium nitrate crystal is calcium nitrate tetrahydrate crystal.

Step S114: removing calcium nitrate crystal to obtain clear liquid.

Wherein the method for removing the calcium nitrate crystals is filtration. In particular, the filtration device is a CN type filter.

, removing the crystal, concentrating, adding urea to obtain urea calcium nitrate, and recycling the urea calcium nitrate, wherein the urea calcium nitrate is water urea calcium nitrate, dihydrate urea calcium nitrate or mixture of water urea calcium nitrate and dihydrate urea calcium nitrate.

Or removing slag from the removed calcium nitrate crystal, concentrating, and adding urea and potassium-containing salt to prepare urea potassium calcium nitrate and urea calcium nitrate, wherein the urea potassium calcium nitrate is aqueous urea potassium calcium nitrate, dihydrate urea potassium calcium nitrate or a mixture of aqueous urea potassium calcium nitrate and dihydrate urea potassium calcium nitrate, and the urea calcium nitrate is aqueous urea calcium nitrate, dihydrate urea calcium nitrate or a mixture of aqueous urea calcium nitrate and dihydrate urea calcium nitrate, and steps are carried out, and the potassium-containing salt is at least selected from potassium feldspar, potassium chloride, potassium nitrate, potassium sulfate and potassium dihydrogen phosphate.

Step S115: and introducing ammonia gas into the clear liquid to obtain a neutralized liquid.

Step S116: and concentrating the neutralized solution to obtain concentrated slurry of the nitrophosphate fertilizer.

Wherein, in the step of concentrating the neutralized liquid, the neutralized liquid is concentrated by an evaporator.

Wherein the mass percentage concentration of the nitrophosphate concentrated slurry is 95-99%.

After the step of concentrating the neutralization solution, the step of concentrating the neutralization solution further comprises a step of performing polymerization reaction on the concentrated neutralization solution to form polyphosphate with the effect of activating soil, so that the fertilizer utilization rate is improved.

, in the step of polymerization, the temperature of polymerization is 175-200 ℃, and the time of polymerization is 20-60 min, specifically, the rate of polymerization of the nitrophosphate concentrated slurry is 3-13%.

Step S120: and (3) carrying out spraying granulation on the molten slurry under a pressurized condition by adopting a steam atomization mode to obtain the nitrophosphate fertilizer.

Wherein, in the step of carrying out spray granulation on the fused slurry under the pressurized condition by adopting a steam atomization mode, the pressure of steam is 0.3 Mpa-2.0 Mpa. Specifically, the molten slurry is pressurized and atomized by a spray gun of the pelletizer using steam to coat the molten slurry on a curtain of a raised blade of the pelletizer.

, the method comprises a drying step after the step of spraying and granulating the molten slurry under the condition of pressurization by adopting a steam atomization mode, wherein in the drying step, the drying temperature is 100-130 ℃, and the drying time is 14-16 min.

And , after the drying step, cooling the material, wherein the discharging temperature is 30-50 ℃ after cooling, and the cooling time is 5-30 min.

Specifically, after the step of cooling, a step of sieving is further included. Wherein the aperture of the screen is 2.0 mm-4.5 mm, so as to obtain the nitrophosphate fertilizer with the particle size of 2.0 mm-4.5 mm.

referring to fig. 2 to 5, wherein, the step of spraying granulation of the molten slurry under pressure by steam atomization is carried out by using a roller 100, the roller 100 has a propelling zone 110, a lifting zone 120 and a cooling zone 130 connected in series in sequence, the material passes through the propelling zone 110, the lifting zone 120 and the cooling zone 130 in sequence in the roller 100, the retention time of the material in the roller 100 is 15min to 30min, wherein, the propelling zone 110 of the roller 100 is provided with a shoveling plate 111, the lifting zone 120 is provided with a second shoveling plate 121, the cooling zone 130 is provided with a third shoveling plate 131, and is that, the shoveling plate 121 of the lifting zone 120 of the roller 100 is 126 °, specifically, the diameter of the roller 100 is 2.8m to 5.0m, and the length of the roller 100 is 20m to 30 m.

The method comprises a step of spraying and granulating the molten slurry under a pressurized condition by adopting a steam atomization mode, and a step of adding a return material, wherein the mass ratio of the return material to the molten slurry is 3: 1-5: 1. Wherein, the returned material is the nitrophosphate fertilizer which is sieved and crushed without meeting the upper and lower limits of the particle size distribution specified by the granulated fertilizer.

The preparation method of the nitrophosphate fertilizer at least has the following advantages:

1) according to the preparation method of the nitrophosphate fertilizer, the nitrophosphate fertilizer is prepared in a steam atomization mode, the situation that the nitrophosphate fertilizer slurry blocks a spray head can be avoided under the action of steam, so that the production efficiency of the nitrophosphate fertilizer is improved, meanwhile, compared with a dry air atomization mode, a step of drying air is omitted in the steam atomization mode, the production flow is simplified, the production efficiency is further improved in the step, and compared with a double-shaft granulation process, the photoplethality of the nitrophosphate fertilizer prepared by a slurry spraying granulation process is better.

2) According to the preparation method of the nitrophosphate fertilizer, the nitrophosphate fertilizer is prepared by adopting a steam atomization mode, and compared with a dry air atomization mode, the steam atomization mode omits the step of drying air, so that energy is saved; in addition, compared with a high tower granulation process, the slurry spraying granulation process does not need to convey viscous nitrophosphate slurry to a high tower, so that the energy consumption is low, and the energy is saved. Therefore, the preparation method of the nitrophosphate fertilizer has the advantage of saving energy.

3) And in the step of concentrating the neutralization solution to obtain the concentrated slurry of the nitrophosphate fertilizer, the step of carrying out polymerization reaction on the concentrated neutralization solution to form polyphosphate with the effect of activating soil, so that the concentrated slurry of the nitrophosphate fertilizer contains the polyphosphate, and the fertilizer utilization rate of the nitrophosphate fertilizer is improved.

4) The concentrated slurry of the nitrophosphate fertilizer is heated to 125-170 ℃ for melting, and the water in the concentrated slurry of the nitrophosphate fertilizer can be removed, so that the nitrophosphate fertilizer prepared has less water content and higher stability.

The nitrophosphate fertilizer prepared by the preparation method has the advantages of uniform particles, better light roundness, high strength, low moisture content and high fertilizer utilization rate. Wherein the strength of the nitrophosphate fertilizer can reach 30N-80N.