JPS6052111B2 - Manufacturing method for fertilizer granules - Google Patents

Description

[Detailed description of the invention] The present invention relates to the production of fertilizer granules.

The purpose is to add phosphoric acid solution to fine particles of fused phosphorus fertilizer (including those that guarantee soluble manganese and/or soluble boron), and react only with the surface layer of the particles to form a double structure. The purpose of the present invention is to create primary particles and combine a large number of these primary particles to provide a fertilizer granulated to a desired particle size.
Furthermore, it is possible to provide a highly sophisticated fertilizer in which fertilizer components such as nitrogen and potassium are also added to the fertilizer. By the way, the present inventors first reacted the specified molten phosphorus fertilizer with phosphoric acid,
A method for producing granules of modified fused phosphorous fertilizer was developed (Japanese Patent Application No. 13585/1983).

However, several unresolved problems have been found in order to produce it industrially in large quantities and in an advantageous manner. The present invention further improves on this technique. Generally, pack mills, kneaders, and various other types of mixers are used to mix and react powders with liquids.

In this case, it is possible to react, but it is usually not possible to granulate immediately, so it is possible to make a paste and then dry it, then coarsely crush the cake and sieve it to size, or finely crush it and then granulate it again. Methods such as running the slurry in a dryer or spraying the slurry into a dryer are used. However, these methods are not suitable for the actual purpose of forming a reaction layer only on the surface layer of particles containing a large amount of soluble phosphoric acid and granulating them without destroying the two-layer structure. In fact, when pack mills, ribbon mixers, and continuous kneaders react with concentrated phosphoric acid solutions, the precipitated silica gel forms a viscous solid mass, making it difficult to mix the materials uniformly, making it difficult not only to granulate the materials, but also to the reaction itself. I also couldn't do it smoothly. On the other hand, various reaction methods and devices centered on granulation have been devised.

For example, there is a drum-shaped ammonitor developed by TVA in the United States, but in this case, the reaction takes about the same amount of time as one powder, and there are periods when the reaction product is extremely sticky, so the reaction does not proceed smoothly. There are doubts about performing granulation. In other words, the reactivity of the phosphoric acid solution is selected to be somewhat inert and has a high viscosity, so there is a strong tendency for partial wetting of fine particles to occur and large lumps to form immediately.
The yield of granulation is poor (40% or less) and the range of the amount of phosphoric acid added is severely limited. On the other hand, in order to improve the drawbacks of the drum-type granulator, a granulator has been devised in which an agitator is provided inside a rotating cylinder at a position opposite to the rotation direction of the drum and set back from the rotation direction. As a result of experiments using such a device, the material was scattered by the stirring blade, the uniform spraying of the phosphoric acid solution was unexpectedly extremely unsatisfactory, large lumps were formed, and there was significant adhesion to the inside of the cylinder. Therefore, the desired granules could hardly be produced. The present inventors completed the present invention as a result of intensive research in view of the above points.

That is, the gist of the present invention is to use a horizontal cylindrical rolling device as shown in FIGS. 1 and 2 to react phosphoric acid with molten phosphorous fertilizer having a specified specific surface area. and granulating the material to impart a water-soluble phosphoric acid content to the particle surface of the material. It depends on the construction method. The horizontal cylindrical rolling device used in the present invention has a large number of stirrer shafts 2 inside a rotating cylinder 1, which are parallel to the central axis of the cylinder and eccentrically downward toward the rotational direction of the cylinder. A stirrer consisting of raking blades 3. It is equipped with the following.

In carrying out this reaction and granulation, the object of the present invention could be achieved by always operating the stirrer and rotating cylinder in the same direction. That is, fine-grained molten phosphorous fertilizer is charged from a hopper 5 installed at one end of a rotating cylinder, and at the same time, the reactivity is adjusted and Lts phosphoric acid solution is supplied from a spray nozzle 4 suitable for forming sufficiently fine droplets. Spray.

The specific surface area of the molten phosphorous fertilizer is adjusted depending on the desired quality of the final product. As the cylinder rotates, the fine-grained product moves upward due to friction with the inner surface of the cylinder, and then descends in an avalanche, but this situation has become extremely suitable for uniform spraying by operating the agitator that rotates in the same direction as the cylinder. Improved, without producing large lumps due to local unevenness.
Mixing and reaction occur uniformly throughout the fine particles. After the start of granulation, the rolling granulation movement is promoted, and particles with a smooth surface suitable for granular fertilizer (for example, particles with a particle size of 2 to 379!) are
It can be collected from the chute 6 with a yield of 0% or more. This rotating cylindrical rolling device may be used in a batch mode or in a continuous mode in which material is continuously fed from one end and granules are removed from the other end. In the case of a continuous type, the cylinder may be slightly inclined, or the cylinder may be horizontal and the material may be conveyed by adjusting the angle of the stirrer blades. The rotational speed of the stirrer does not have to be very rapid. The respective rotational speeds are adjusted depending on the type of raw materials used and the quality of the finished product, but in most cases, good results can be obtained when the rotational speed of the agitator shaft 2 is faster than that of the rotating cylinder 1. In addition,
It is required that the phosphoric acid solution added during the reaction granulation process completely reacts to eliminate the free acid, and that it remains in a water-soluble form. In order to complete these steps in a relatively short period of time, it may be necessary to accumulate the required amount of heat and appropriately control water evaporation. By finely adjusting the overflow amount and the exhaust amount from the suction port 7, it is possible to set the internal reaction temperature to a desired point. The particle size of the finished granules is usually 2~
It is desirable to adjust to 37W1, but depending on the application conditions or the particle size of the mixed material during bulk blending, it may be adjusted to 1-2Ttm or 3-5Ttm.
It can be arbitrarily adjusted such as wn14 to 6Tm.

In other words, the desired value is determined not only by the amount of the raw phosphoric acid solution but also by the combination of the conditions governing its electrical conductivity (concentration, temperature, dissolved components, etc.), the injection rate of the phosphoric acid solution, the holding temperature of the reaction system, etc. The particle size can be changed. The granulated product obtained by the method of the present invention is easy to classify and generates few fine particles, especially during bulk blending, and the finished particles have a true spherical shape with a smooth surface, which was measured using a shell hardness tester. It has a hardness of 4K9/1 grain, which is sufficiently large, and has sufficient resistance to destruction during mixing operations and transportation, and also has the characteristic of quickly softening and disintegrating when placed in water.

The fused phosphorus fertilizer used in the present invention further includes B2O3, Mn2O
It may also contain trace elements such as 3.

If necessary, for example, phosphorizing slag, blast furnace slag, or other non-ferrous metallurgy slag, all of which have granulated amorphous calcium silicate or magnesium silicate as their main components, may be used in combination. The molten phosphorus fertilizer is rosin ● Rammler (
The volume-based specific surface area obtained by the approximation formula of the ROsin-Rammler) distribution is 200 ~ with the shape factor being 1.
It is necessary to use fine particles with a range of 600 cIt/d. On the other hand, it is necessary to adjust the reactivity of the phosphoric acid solution, and in particular, it is necessary to have a specific conductivity of 0.20 ohm-1 cm-1 or less at 25 DEG C. and a concentration of 65% or more as H3PO4. Furthermore, in the present invention, when reacting and granulating the above-mentioned fused phosphorous fertilizer and phosphoric acid, fertilizer components such as nitrogen and potassium may be added. In this case, fertilizer components such as nitrogen and potassium may be added to the basic material in advance, or may be added during the reaction with phosphoric acid. It is also possible to use it by adding or dissolving it in a phosphoric acid solution. ), it is possible to effectively produce a compound fertilizer having a double structure regarding phosphoric acid in the same manner as described above. When a fertilizer with a dual structure regarding phosphoric acid is applied to soil water, the water-soluble phosphoric acid in the surface layer rapidly dissolves in the soil water and effectively affects the early growth of crops, and the base layer in the inner layer dissolves rapidly in the soil water. This material has a unique fertilizing effect as well as a soil conditioner effect. In addition,
After a certain period of time in the soil, water-soluble phosphoric acid that remains inside the fertilizer particles is slowly captured, and extremely fine CaHPO4.2H20, . It generates MgHP04, 3H20, etc., and while maintaining a fast transfer rate into soil water, prevents the fixation of phosphoric acid in the soil for a certain period of time, and maintains availability to plants for a long period of time, making it a unique product. We hope that it will be effective as a fertilizer.

The silica gel produced by the reaction is extremely convenient as a medium for loading water-soluble or surface layer components. The present invention will be explained below with reference to Examples.

All percentages represent weight. Example 1 Using a horizontally rotating cylindrical rolling device with a diameter of 850 TIr1n and a length of 150 h as shown in Fig. 1, with the stirrer and rotating cylinder 1 rotating in the same direction, molten phosphorus fertilizer (590μ
The specific surface area of R5O obtained by passing through the sieve and using the approximation formula of Rosin-Rammler distribution is 3 when the shape factor is 1.
11.2 cIt/d) 123.4k9 was charged from hopper 5, while 75% phosphoric acid (specific conductivity at 25°C 0.
0700-1. C! Rl-liquid 55.9k9 was sprayed from the spray nozzle 4.

The reaction and granulation were completed within about one particle from the start of spraying, and by tilting the entire apparatus, 27fn~3 granules were obtained from chute 6, with a yield of 85%. The fertilizer component of the slightly dried product is 535.5% C/P2O, of which W
-P2O, was 21.0%, and C.MgO was 8.6%. Example 2 Diameter 600TVn1 Length 4000T as shown in Fig. 1
Using a 0t horizontally rotating cylindrical rolling device, the same molten phosphorus fertilizer as in Example 1 was applied at 123.0 k9/h with the stirrer and rotating cylinder 1 rotating in the same direction as in Example 1.
75% phosphoric acid (specific conductivity at 25°C 0.070
0-1. cTn-1) was sprayed at a rate of 55.7k9/Hr for continuous operation, and 2T was sprayed from chute 6.
Granules of f0n to 3W1n could be obtained with a yield of 81% with good reproducibility and under good operating conditions.

The fertilizer component of this finished product (after drying) is C・P2O, 35
．． 4%, of which 20.6% to W-P2, C...MgO
It was 8.3%.

Example 3 Using the device of Example 1 and under similar rotational conditions, B
1, O3 and MnO (specific surface area: 310c!i/d, with the shape factor determined by the Rosin-Rammler distribution approximation formula as 1) 57.1kg, potassium chloride 44.
9k9 and 20.3 kg of urea were charged from hopper 5, and
5% phosphoric acid (specific conductivity at 25°C 0.070Ω-1c
m-1) When 34.5 kg of the liquid was sprayed from the spray nozzle 4, a granulated product of 2 to 4 W$L was obtained, and the granulation yield was 8.
7)%.

The fertilizer components after drying were as follows. Example 4 The same apparatus and the same melted phosphorous fertilizer as in Example 1 were used, the blending ratio was the same as the phosphoric acid solution, and the following conditions were used.

&JVVVko4u▼ノ ~5kU1shi→TLX. υ●υ
υ1 exposure u νI Spray phosphoric acid solution in the same manner as in Example 1,
At this time, the temperature of the reaction system was kept lower than in Example 1 by adjusting the amount of ventilation at the suction port.

The finished product becomes large particles, 3T! Rln~6Wg
The yield in the n range is 87%, and the fertilizer component of the product is C-
P2O536. O%, of which W●P2Q2O. 5%, C
IMgO was 8.9%. Comparative example 1 length 2500rw
11 Charge 60k9 of the same molten phosphorous fertilizer as in Example 1 into a bag mill with a width of 40'', and charge 25k9 of the same 75% phosphoric acid solution as in Example 1.
was scattered.

The mixture formed into a strongly sticky lump that caused a blockage between the bottom and blades of the bag mill, and climbed up to the top of the bag mill, making it impossible to operate. Comparative example 2 Length 2000T! r! n1 width 400Tn! An experiment similar to Comparative Example 1 was conducted using a continuous kneader of n.

The results were very similar to those in Comparative Example 1, in which a granulated product could not be obtained. Comparative Example 3 The same equipment and the same amount of materials as in Example 1 were used, the rotation direction of the stirrer was rotated at high speed in the opposite direction to the cylinder, and the stirrer shaft was set back and eccentrically with respect to the rotation direction of the cylinder. I made it.

Carefully adjust the position of the phosphoric acid liquid spray nozzle, spray angle, etc.
Even though the spray direction was set to be the best for the material, significant adhesion to the inner wall of the cylinder occurred, and many large lumps of 30 to 50" size and powdery products were generated. Comparative Example 4 Implementation The experiment was conducted using the same equipment and materials as in Example 1, but with the stirrer removed in this case.

Because the gravity of the molten phosphorus fertilizer, the centrifugal force due to the rotation of the cylinder, and the friction on the inner wall of the cylinder are not balanced, the lifting and rolling movement of the material is insufficient, and uniform spraying of the phosphoric acid solution is not achieved.
A large amount (more than 90%) of 60 pieces of large lumps was produced.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an example of a horizontal cylindrical rolling device used in the present invention, and FIG. 2 is a cross-sectional view thereof. DESCRIPTION OF SYMBOLS 1... Rotating cylinder, 2... Stirrer shaft, 3... Scraping blade, 4... Spray nozzle, 5... Hopper, 6... Ut, 7... Suction port.

Claims (1)

[Scope of Claims] 1. An agitating device which is constructed of a large number of scraping blades inside a rotating cylinder, each having a shaft that is parallel to the central axis of the cylinder and eccentrically downward toward the rotational direction of the cylinder. Using a horizontal cylindrical rolling device equipped with a stirrer, and with the stirrer and rotating cylinder rotated in the same direction, the specific surface area on a volumetric basis was determined by the approximate formula of the Rosin-Rammler distribution. When the shape factor is 1, the powder of fused phosphorus fertilizer is in the range of 200 to 600 cm^2/cm^3 and the specific conductivity is 0.20Ω at 25℃.
^-^1cm^-^1, and is characterized by reacting with phosphoric acid at a concentration of 65% or more as H_3PO_4 and granulating it to impart a water-soluble phosphoric acid content to the surface of the material particles. manufacturing method. 2. The method for producing fertilizer granules according to claim 1, characterized in that fertilizer components such as nitrogen and potassium are added during the reaction and granulation of the fused phosphorous fertilizer powder and phosphoric acid.