JPH10167864A - Quick-acting and slow-release fertilizer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the caking due to the insolubilization of the phosphatic component and moisture absorption and to obtain a phosphatic fertilizer excellent in quick-acting and slow-release fertilizing effect by composting the fertilizer mainly of a water-soluble phosphate and a citric-soluble phosphate and covering the phosphatic component with a silica gel. SOLUTION: The phosphatic material is decomposed by phosphoric acid into a slurry. Light-burned magnesia is added as a viscosity control agent to adjust the viscosity of the slurry to 2000-5000cP, preferably 2700-4000cP, (80 deg.C) and the acidity to 1.4-1.8, a powdery silicate material is added, and the admixture is granulated by a granulator into the grain having 2-4mm diameter. A granulated quick-acting and slow-release phosphatic fertilizer with the phosphatic component covered with the formed silica gel, contg. >=20wt.% phosphoric acid and 4.5-12wt.% silica gel and with the citric-solubilization ratio of phosphoric acid controlled to >=95% and the water solubilization ratio to 35-65% is obtained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphate fertilizer which prevents insolubilization of a phosphoric acid component and prevents caking due to moisture absorption, and has an excellent balance of mixing a fast-releasing phosphoric acid component. More specifically, it contains a well-balanced water-soluble and water-soluble phosphoric acid component and prevents insolubilization of water-soluble phosphoric acid in soil. The present invention relates to a phosphate fertilizer that has no inconvenience and has an excellent anti-caking effect against moisture absorption.

[0002]

2. Description of the Related Art Phosphate fertilizers usually contain, as fertilizer components, a fast-acting water-soluble phosphoric acid (mainly monocalcium phosphate) and a slow-acting co-soluble phosphoric acid (mainly dicalcium phosphate). However, water-soluble phosphoric acid is easily eluted and fixed to the soil, and as a means to prevent this, fertilization is carried out by wrapping a phosphate fertilizer in compost etc. There are problems such as. In general, fertilizers must be carefully combined with other fertilizers due to their chemical properties, so that mutual reaction does not impair the fertilizer effect.However, this is when adding other fertilizer components to phosphate fertilizer. The same applies to, for example, the problem that when active iron is added, it reacts with water-soluble phosphoric acid to generate insoluble iron phosphate and insolubilize it. Therefore,
Conventional iron-containing phosphate fertilizers contain iron by a method such as increasing the content of quorous phosphoric acid in place of water-soluble phosphoric acid. And the effect of promoting early growth of rice cannot be expected. In addition, conventional phosphate fertilizers are highly hygroscopic and solidify during storage due to moisture in the air,
There is a problem that it has to be crushed at the time of use.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the conventional phosphate fertilizer, and effectively prevents insolubilization of the phosphoric acid component and solidification due to moisture absorption, thereby achieving a fast-releasing fertilizing effect. It aims to provide an excellent phosphate fertilizer. Phosphate fertilizer of the present invention, by preventing the immobilization of the fertilizer component, does not reduce the fertilizer effect even if it contains iron, it can be used as an excellent iron-containing phosphate fertilizer or iron-containing magnesia phosphate fertilizer. it can.

[0004]

That is, the present invention relates to a phosphate fertilizer having the following constitution. (1) water-soluble phosphoric acid and potassium-soluble phosphoric acid as main components,
A fast-releasing phosphate fertilizer characterized in that the phosphoric acid component is included in gel silica to prevent insolubilization and solidification of the phosphoric acid component. (2) The phosphoric acid content is 20 wt% or more, the gel silica content is 4.5 to 12 wt%, and the phosphoric acid solubilization rate is 95%.
As described above, the phosphate fertilizer according to (1), wherein the water solubility is 35 to 65%. (3) iron and / or water-soluble phosphoric acid,
Or the phosphate fertilizer according to the above (1) or (2), comprising a phosphate component or a phosphate component or a phosphate component, wherein the iron component and / or the phosphate component are included by gel silica. (4) The phosphoric acid according to the above (3), wherein the phosphoric acid content is 20 to 35 wt%, the iron content is 20 to 32 wt% in terms of iron oxide, and the magnesia component content is 1 to 16 wt% in terms of magnesium oxide. fertilizer. (5) The phosphate fertilizer according to the above (4), wherein the content of the soluble magnesium component is 4 to 10 wt% in terms of magnesium oxide.

Further, the present invention relates to a method for producing the above-mentioned phosphate fertilizer shown below. (6) A phosphoric acid decomposition slurry is used as the phosphoric acid raw material, and the acidity of the slurry is adjusted to 1.4 to 1.8, and a powdery silicic acid raw material is added to form a gel. A method for producing a fast-releasing phosphate fertilizer, comprising producing a phosphate fertilizer containing a phosphate component by silica. (7) Light calcined earth is added as a viscosity modifier for the slurry, and the viscosity of the slurry is adjusted to 2000 to 5000 cp, preferably 270
The production method according to the above (6), wherein the temperature is adjusted to 0 to 4000 cp (80 ° C.). (8) The production according to the above (6) or (7), wherein phosphate ore or heavy superphosphate is used alone or in combination as a phosphoric acid raw material, and the phosphoric acid raw material is decomposed with phosphoric acid sulfuric acid to form a slurry. Method. (9) In the presence of silicic acid raw material, powdered magnesia raw material and / or
Or a method for producing a phosphate fertilizer comprising adding a raw material of iron and a phosphate component or a phosphate component and a formic acid component or an iron component by gel silica to produce a phosphate fertilizer according to any one of the above (6) to (8). .

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be specifically described below. (I) Composition and properties of fertilizer The phosphate fertilizer of the present invention comprises water-soluble phosphoric acid and potassium-soluble phosphoric acid as main components, and these phosphoric acid components are contained by gel silica. It is. Generally, water-soluble phosphoric acid (such as monocalcium phosphate: CaH ₄ (PO ₄ ) ₂ ) that is easily absorbed is required in the early stage of growing a crop, but the effect is fixed to soil quickly and the effect does not last long. On the other hand, dissolving phosphoric acid (dicalcium phosphate: CaHPO ₄ , magnesium phosphate: MgH ₂ PO ₄
Is difficult to be fixed to the soil, but is absorbed slowly in the early stage of growth and exerts its effect after the middle stage of growth. The phosphate fertilizer of the present invention is mainly composed of a fast-acting water-soluble phosphoric acid and a slow-acting quorous phosphoric acid, and these phosphoric acid components are contained by gel silica. There is no inconvenience that phosphoric acid reacts with iron in soil early to form insoluble iron phosphate, and an effective fertilizing effect can be obtained over a long period from the early stage to the late stage of growing a crop. In the present invention, water-soluble phosphoric acid and potassium-soluble phosphoric acid as the main components mean that the total phosphoric acid content in the fertilizer is 20% by weight or more and is higher than other fertilizer components, for example, iron and mafic components. It mainly means that the phosphoric acid content is high, but when the total phosphoric acid content is 20 wt% or more, the case where the iron content is higher than the phosphoric acid content is also included.

[0007] The phosphate fertilizer of the present invention preferably has a phosphoric acid content of 20 wt% or more, a gel silica content of 4.5 to 12 wt%, and a phosphoric acid solubilization rate (the amount of phosphoric acid in the total phosphoric acid). The ratio of soluble phosphoric acid) is 95% or more, and the water solubility (the ratio of water-soluble phosphoric acid in the total phosphoric acid) is 35 to 65%. More preferably, the phosphoric acid content is 25 wt% or more, the solubilization rate of phosphoric acid is 97% or more, and the water solubility is 50 to 65%. Specifically, in a preferred embodiment, the total phosphoric acid content is about 30 wt%
Is about 28.5 to 30% by weight of water-soluble phosphoric acid and about 14 to 20% by weight of water-soluble phosphoric acid. The water-soluble phosphoric acid partially includes water-soluble phosphoric acid. When the proportion of the water-soluble phosphoric acid is less than 95%, the content of the water-soluble phosphoric acid relatively increases, so that the rapid effect becomes higher. On the other hand, when the proportion of the water-soluble phosphoric acid is more than 65%, the relative effect becomes higher. In addition, the content of citrate-soluble phosphoric acid is low, and the slow release effect is poor, and the fertilizing effect in the late growth stage of paddy rice or the like is undesirably reduced. On the other hand, if the proportion of the water-soluble phosphoric acid is less than 35%, the fast-acting effect is undesirably reduced.

When the content of phosphoric acid is less than 20% by weight, the content of the phosphoric acid component is small. Therefore, in order to enhance the fertilizing effect as a phosphate fertilizer, the content is suitably at least 20% by weight, preferably at least 25% by weight. When an iron component and / or a magnesia component are contained together with the phosphoric acid component, the content of the phosphoric acid is preferably 20 to 35% by weight, and more preferably 25 to 35% by weight in consideration of the iron content and the magnesia component content. It is.

The above-mentioned phosphoric acid component is included in the gel silica produced in the production process. FIG. 1 schematically shows such a state of the phosphoric acid component. As shown in the figure, the particles 10 of the phosphoric acid component (compound) exist in a state where their surfaces are wrapped by silica 11. The silica 11 is in a gel state generated in a manufacturing process. In the present invention, being included in the gel silica means that the entire surface of the component particles such as phosphoric acid is covered with the gel silica, or that most of the particle surface is covered with the gel silica. This means that the particle surface is not necessarily completely covered.

[0010] The gel silica has a role of protecting fertilizer components such as phosphoric acid, and absorbs moisture in the air that has entered the fertilizer to prevent the fertilizer from solidifying. In addition, the reaction between fertilizer components is suppressed to prevent a decrease in fertilizer effect. Therefore, when an active iron component is contained together with phosphoric acid as a fertilizer component, the reaction between water-soluble phosphoric acid and iron component is suppressed, and phosphoric acid is prevented from being insolubilized as insoluble iron phosphate.

It is necessary that the above-mentioned gel silica is produced in a manufacturing process. Specifically, for example, phosphoric acid ore is made into a phosphoric acid decomposition slurry, a silica material is added when granulating by adjusting the viscosity of the slurry to generate gel silica, and a fertilizer component such as a phosphoric acid component is produced. The particles are granulated and the particles are encapsulated by gel silica. In place of the gel silica produced in such a production process, a fertilizer obtained by adding a commercially available gel silica such as silica gel to the fertilizer after the fertilizer production cannot obtain the effects of the present invention. The reason for this is that when the gel-like silica is added after the fertilizer production, the gel-like silica is only dispersed between fertilizer components such as phosphoric acid, whereas the gel-like silica produced through the production process is It is thought that this is because it exists so as to enclose fertilizer components such as phosphoric acid.

The content of the gel silica is suitably at least 4.5 wt%. If the amount is less than this, the effect of preventing solidification and preventing insolubilization is insufficient. In addition, when the content of the gel silica exceeds 12 wt%, when the fertilizer is granulated, the weight of the granules becomes undesirably small.

[0013] The phosphate fertilizer of the present invention includes those containing iron in addition to quosoluble phosphoric acid, water-soluble phosphoric acid and gel silica. In rice cultivation, it is known that sufficient iron is supplied in the late growth stage to prevent the phenomenon of “fall in autumn”. However, as mentioned above, simply adding iron (Suppliable) Phosphoric acid reacts with iron to produce insoluble iron phosphate, and the available phosphoric acid and iron are fixed, so that a sufficient fertilizing effect cannot be obtained.
In the phosphate fertilizer of the present invention, the phosphate component and iron content are wrapped by the gel silica, and the reaction of these water-soluble phosphoric acid and iron component is suppressed. Along with sufficient iron. Therefore, the phosphate fertilizer of the present invention is also useful as a source of iron supply to field crops and the like. In a preferred embodiment of the present invention, the content of iron is 20 to
32 wt%.

[0014] The phosphate fertilizer of the present invention includes those containing not less than 1 to 16% by weight, in terms of magnesium oxide, of a magnesia component together with soluble phos- phoric acid, water-soluble phosphoric acid and gel silica. In addition, an embodiment containing a magnesia component together with iron is included. Magnesium helps phosphoric acid work and promotes crop growth. The phosphate fertilizer of the present invention contains a magnesia component in the form of mica phosphate. Phosphoric acid magnesia is more easily absorbed by crops than other forms of magnesia and has a better fertilizing effect. In a preferred embodiment of the present invention, 4 to 10% by weight of the magnesia component contained in the phosphate fertilizer in terms of magnesium oxide is soluble magnesia.

The phosphate fertilizer preferably has an average particle size of 4
~ 2mm granular material. Because it is a granular material, it is easily mixed with other fertilizers, and is suitable as a compound fertilizer or a bulk blending fertilizer. In addition, since it has an effect of preventing solidification against moisture absorption, not only is the phosphate fertilizer itself difficult to solidify, but also when mixed with other fertilizers, an effect of preventing solidification of the whole mixed fertilizer can be obtained.

(II) Production Method According to the present invention, there is provided a wet production method of the above-mentioned phosphate fertilizer in which insolubilization and consolidation are prevented by including a fertilizer component with gel silica. That is, the phosphoric acid fertilizer uses a phosphoric acid raw material as a phosphoric acid decomposition slurry, and if necessary, adds a clay component for adjusting the slurry viscosity to the phosphoric acid raw material to reduce the acidity of the slurry to 1.4 to 1.8. It can be manufactured by adjusting and adding a powdery silicic acid raw material to granulate.
As the phosphoric acid raw material, phosphate rock and heavy perphosphate can be used alone or in combination. Since heavy superphosphate is obtained by dissolving phosphoric acid in phosphoric acid, it is advantageous because it contains more phosphoric acid than phosphate ore. Also, since it is water-soluble, it is easy to form a slurry.

These phosphoric acid materials are decomposed with phosphoric acid to form a slurry. As the phosphoric acid, sulfuric acid mixed with sulfuric acid is preferably used. By using phosphoric acid, phosphate rock can be decomposed in a shorter time than phosphoric acid alone. The mixing ratio of sulfuric acid and phosphoric acid is usually around 0.5 (see Example Table 1), but is not limited thereto. Any mixing ratio may be used so long as the phosphoric acid raw material is decomposed in 2 to 3 hours.

By the above-mentioned slurrying treatment, calcium fluoride calcium phosphate (CaF (PO ₄ ) ₃ ), which is a main component of the phosphate rock, is decomposed by phosphoric acid, and monocalcium phosphate CaH ₄ (PO ₄ ) ₂ and gypsum Ca
Produce and SO _4. This decomposition reaction makes the slurry about 8
Heat is generated at 0 to 90 ° C., and fluorine gas or the like generated by decomposition of the phosphate rock volatilizes to the outside. After slurrying, about 3 ~
Preferably, the reaction is allowed to proceed for about 4 hours. This phosphoric acid decomposition slurry has a viscosity corresponding to the acidity. As described above, when the slurry is formed, the decomposition of the phosphoric acid raw material mainly produces monocalcium phosphate and gypsum, and after the slurry is formed, the generated monocalcium phosphate gradually reacts with the lime and phosphoric acid. At the stage where dicalcium is produced and sent to the granulation process, the slurry contains water-soluble monocalcium phosphate and potassium-soluble dicalcium phosphate.

Incidentally, in a general production method of superphosphate lime,
Phosphate ore is decomposed by sulfuric acid to produce monocalcium phosphate and gypsum, and this decomposition reaction is similar to the present invention,
In the conventionally known chemical conversion type production method, the aging reaction proceeds in the interior of the composition to produce a porous solid. On the other hand, in the production method of the present invention, a slurry state having a predetermined viscosity is maintained, and just before the slurry is hardened, a powdery silicic acid raw material is added and sent to a granulation step to generate gel-like silica, and the gel-like silica is used. It encloses fertilizer component particles such as phosphoric acid, and this point is fundamentally different from the conventional production method.

In the production method of the present invention, the viscosity of the slurry at 2000 is from 2,000 to 5,000 cp, preferably from 2 to 5000 cp.
It is adjusted to 700-4000 cp. In the case of 70 ° C., preferably, about 3700 to 5500 cp is appropriate.
If the viscosity of the slurry is not adjusted to an appropriate range, the fertilizer component cannot be enveloped by the gel silica. That is, when the viscosity of the slurry (80 ° C.) becomes about 1000 cp, the slurry keeps the fluid state for a long time, so that the gel silica produced by adding the silicic acid raw material is uniformly incorporated into fertilizer components such as phosphoric acid. As a result, the insolubilization of the phosphoric acid component cannot be effectively prevented because the coating with the gel silica is insufficient. In addition, the granulated material is also likely to be small. On the other hand, when the viscosity of the slurry is about 5500 cp (80 ° C.), the slurry hardens immediately and granulation becomes difficult, and it becomes impossible to enclose the fertilizer component with the gel silica. Therefore, the viscosity of the slurry at 80 ° C. is 2
000-5000cp is suitable, 2700-4000
cp is preferred. In this range, the particles of the fertilizer component are well covered with the generated gel-like silica, and the insolubilization of phosphoric acid can be effectively prevented.

The viscosity of the slurry is determined by its acidity (Acidu
lation), and the lower the acidity, the higher the viscosity of the slurry. Therefore, the slurry viscosity can be controlled in an appropriate range by adjusting the acidity. This acidity is represented by the molar ratio of the acidic component to the alkaline component. The acidic component is mainly a liquid component of phosphoric acid and sulfuric acid contained in the phosphoric acid raw material and the sulfuric acid, and the alkali component is a solid component such as lime mainly contained in the phosphoric acid raw material. If the amount of the alkali component is increased, the viscosity of the slurry can be increased. Therefore, light burnt clay is added as a viscosity modifier for the slurry. The acidity of the slurry to which light baking earth as a viscosity modifier is added is represented by the following equation. Acidity = (P ₂ O ₅ + H ₂ SO ₄ ) / (CaO + MgO) (molar ratio) As shown in Table 1 in Examples described later, the viscosity of the slurry is higher than that of lime in the alkali component. The influence of the magnesia content is large, and therefore, the adjustment of the slurry viscosity is mainly performed by adding the magnesia component. The grit in the slurrying process is a viscosity modifier, and is distinguished from a grit material such as serpentine added as a grit component to be described later.

In the present production method, the acidity of the slurry is suitably from 1.4 to 1.8, whereby the viscosity of the slurry can be maintained in the above range. As shown in the examples described below, the viscosity of the slurry is adjusted to 2700 to 3800 cp (80 ° C.) by adjusting the acidity of the slurry to 1.4 to 1.8.
Can be controlled. The viscosity of the slurry increases as the temperature decreases. However, the temperature of the slurry is preferably maintained at this temperature level because the slurry generates heat at 80 to 90 ° C. due to heat of decomposition reaction when decomposed with sulfuric acid.

At the stage where the decomposition of the phosphoric acid raw material such as phosphate ore has progressed, powdery silicic acid raw material is added and granulated under the above slurry viscosity, and fertilizer components such as phosphoric acid are granulated and gelled. And fertilizer component particles are wrapped by the gel silica. As for the timing of adding the silicic acid raw material, the decomposition of the phosphoric acid raw material proceeds, and it is preferable to add the silicic acid raw material immediately before sending the decomposed slurry to the granulation step, or to add the silicic acid raw material at the start of granulation. As the silicic acid raw material, siliceous slag or the like can be used. In addition,
When adding iron or magnesia as a fertilizer component, it is necessary to add an additional silicic acid raw material if these iron or magnesia raw materials contain a sufficient amount of silicic acid. Absent. For example, when serpentine or the like is used as a raw material for magnesite, serpentine contains a sufficient amount of a silicate component, so that it is not necessary to further add a silicate raw material.

When an iron component or a gypsum component is further added to the phosphoric acid component, it is preferable to add a mixture of a powdery iron component material and a magnesia component during granulation of the slurry to perform granulation. . Serpentine (3MgO ・ 2SiO ₂・ 2H ₂
O) or ferronickel slag (2MgO.SiO ₂ , MgO.SiO ₂ ) or the like can be used. Further, a melted phosphorus fertilizer (fused magnesium fertilizer) may be used. This fused phosphorus fertilizer contains 20 fortresses
% And can be used as a source of hardship. Further, since it contains a phosphoric acid content of about 20%, it is easy to adjust the amount of the phosphoric acid component, and it is also a supply source of the silica content. In addition, since serpentinite contains a sufficient amount of silicic acid together with the magnesite component, it can be used also as a silicic acid raw material. The addition of magnesia raw material, in addition to the magnesia component as a fertilizer component is replenished, the presence of magnesia sources, one lime phosphate reacts with magnesia click soluble phosphate magnesia of (MgH ₂ Since PO ₄ ) is produced, the phosphoric acid solubilization rate is increased.

As the iron raw material, mill scale or iron ore can be used. Alternatively, red iron oxide containing ferric oxide as a main component may be used. Since bengara is obtained as a by-product of the pickling process of a steel plant or a plating plant or the production of titanium oxide, it can be used effectively. The iron and the generated magnesite phosphate are granulated together with monocalcium phosphate and dicalcium phosphate, and the surface thereof is in a state of being enveloped by the gel silica.

It is necessary to add the raw material of magnesia and the raw material of iron in the presence of the silicic acid component. Serpentine composed of magnesia silicate can be used alone, but it is preferable to use a mixture of serpentine and mill scale, which is a raw material of iron. If mill scale or the like is added to the slurry before the silicic acid component, the phosphoric acid component is not covered with the gel silica, so that iron phosphate is generated, and the desired phosphate fertilizer cannot be obtained.

In the above-mentioned production method of the present invention, phosphate ore, sulfuric acid-containing phosphoric acid solution, silicic acid raw material and iron content raw material,
The amount of the mafic raw material used in the manufactured phosphate fertilizer,
Phosphoric acid content is 20 wt% or more, phosphoric acid solubilization rate is 95% or more, water solubility is 35-65%, gel silica content is 4.5-12 wt%, iron content is iron oxide The amount is preferably 20 to 30% by weight in conversion, the content of the formic component is 1 to 16% by weight in terms of magnesium oxide, and the amount of soluble magnesium is 4 to 10% by weight in terms of magnesium oxide. As the granulation means, a general granulator can be used. Preferably, it is granulated to an average particle size of about 2 to 4 mm.

[0028]

According to the phosphate fertilizer of the present invention, since the fertilizer components are protected by the gel-like silica, the reaction between the fertilizer components is suppressed, and the water-soluble phosphoric acid is eluted at an early stage and fixed in the soil. Is prevented. Therefore, the balance between the fast-acting water-soluble phosphoric acid and the slow-acting co-soluble phosphoric acid is well maintained for a long period of time. In addition, since the gel silica absorbs moisture in the air that enters the fertilizer, it is difficult for the fertilizer to solidify. Furthermore, even when active iron is contained together with water-soluble phosphoric acid,
Since the reaction between phosphoric acid and iron is suppressed, phosphoric acid and iron are prevented from being insolubilized as insoluble iron phosphate. Therefore, an iron-containing phosphate fertilizer excellent in fertilizer effect can be obtained.
In addition, those containing a magnesia component also have good absorption of the mica component. In addition, since it has an effect of preventing caking against moisture, when mixed with other fertilizers, an effect of preventing caking of the whole mixed fertilizer can be obtained.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples and comparative examples of the present invention are shown below. In addition, these are illustrations and do not limit the scope of the present invention.

Example 1 For a sample (No. A1-A13) having the compounding amount shown in Table 1, a lightly-burned magnesia as a slurry viscosity modifier and a phosphoric acid sulfuric acid solution were added to a phosphate rock powder to form a slurry. The decomposition of phosphate rock proceeded for hours. On the other hand, a powder was prepared by mixing a mill scale as an iron raw material and a serpentine as a magnesia raw material, and this was added to the above slurry and supplied to a granulator to granulate to an average particle size of 2 to 4 mm. Table 2 shows the composition of the obtained granular phosphate fertilizer. A part of the phosphate fertilizer (No.A3) was analyzed for its components using an analytical electron microscope.
(A) and (B). The composition ratios of the raw materials used and the production conditions are shown in the footnotes of Table 1.

As shown in Table 1, the sample (NoA2-A4) in which the acidity of the slurry is 1.4 to 1.8 has good granulation properties,
As shown in FIGS. 2 (A) and 2 (B), the particles of the phosphoric acid component were in a state where their surfaces were well covered with gel silica. Sample using blast furnace slag as a silica material (No.A6-A7),
And a sample using serpentine alone (No.A8), and a sample in which the amount of lightly burned magnesia was increased or decreased within the above acidity range (No.A9-A1)
0), a sample using molten phosphorus manure as a source of masonry (No.A11), a sample using lime heavy perphosphate as a phosphate source (No.A12), and a sample using red iron oxide as a source of iron (No. .A13) showed good granulation properties and coating with gel silica. On the other hand, the sample (No, A1) having an acidity of 2.0 had an excessively small particle size, and the particle surface was insufficiently covered with the gel silica. In addition, the sample (No. A5) having an acidity of 1.2 could not be granulated, and the desired phosphate fertilizer could not be obtained in any case.

[0032]

[0033]

Example 2 On the basis of sample No. A3 of Example 1, those having different viscosities of the slurries were prepared by changing the amount of lightly burned magnesia (samples No. B1-B5). The granulation properties when granulating to a diameter of 2 to 4 mm were examined. The results are shown in Table 3.
A sample having a slurry viscosity of 2700 to 3500 cp at 80 ° C. shows good granulation properties, and thus has a good coating with gel silica, but a sample having a slurry viscosity at 80 ° C. of less than 2700 (No. B-1). Since iron reacts with phosphoric acid to make phosphoric acid insoluble, the content of water-soluble phosphoric acid is significantly low. Further, a sample having a slurry viscosity exceeding 5500 cp (No.
B4, B5) could not be granulated, and the desired phosphate fertilizer could not be obtained.

[0035]

Example 3 A part of the phosphate fertilizer obtained in Example 1 was subjected to a consolidation test by moisture absorption. As a comparative sample, a sample containing no gel silica (No. C1) and a sample in which the gel silica of the present invention was replaced with commercially available silica gel (No. C2) were also subjected to the same test under the same conditions. In the test, 80 granules of each sample were taken in a Petri dish (width 50 mm × height 30 mm), placed in a desiccator at a humidity of 80% and a temperature of 30 ° C.
After the lapse of time, the number and hardness of the consolidation were measured. The results are shown in Table 4. As shown, the comparative sample (No. C1) containing no gel silica had low hardness of individual granules before the test, and had a high consolidation degree of 87% after the moisture absorption test. The hardness of the granules was as low as 0.5 kg / 2 mm. In the case of replacing the commercially available silica gel, the hardness of the individual granules before the test is equivalent to the sample of the example,
The hardness of the individual granules after the moisture absorption test is greatly reduced to 1.9 kg / 2 mm, and the consolidation degree is as high as 68%. On the other hand, the phosphate fertilizer of the present invention has a consolidation degree of 0% after the moisture absorption test, exhibits an excellent consolidation prevention effect, and has a hardness of each of the granules before and after the test. As it is 4.0 kg / ² mm, the granules themselves are hard and hardly affected by moisture absorption.

[0037]

Example 4 A granulated product (13.7% of soluble phosphoric acid) obtained by mixing 28.2 g of mill scale powder with 78.2 g of granular superphosphate (17.5% of soluble phosphoric acid, 14.5% of water soluble phosphoric acid) , Water-soluble phosphoric acid 11.3
%) As a comparative sample (No. D1), and the sample granulated product of Example 1 (No.
A3) was placed in a desiccator at 30 ° C. and 90% humidity for 7 days together with A3) for aging, and then water-soluble phosphoric acid and potassium iron oxide (Fe
The content of ₂ O ₃ ) was measured, and the reactivity with iron was examined. The results are shown in Table 5. It was confirmed that the amount of water-soluble phosphoric acid in the sample of Example 1 (No. A3) did not change and did not react with iron, whereas the comparative sample (No. Was reduced to about half, and it was confirmed that it was insolubilized.

[0039]

Example 5 The phosphate fertilizer (No. A3) of Example 1 was applied to a mixed soil mainly composed of volcanic ash soil, and the fertilizer effect on spinach was sown on June 18 and harvested on August 19. The test was carried out in a warm garden garden in the Kanto region. In addition, the same test was carried out for those using no iron material (control section) and those using conventional iron material (trade name: Iron Ace 35) (conventional section). The results are shown in Table 6. As is apparent from the results, the fertilizer to which the phosphate fertilizer of the present invention has been applied has an iron content of about 65% higher than that of the control plot and about 45% higher than that of the conventional plot.

[0041]

Example 6 The phosphate fertilizer (No. A3) of Example 1 was applied to a field of marine alluvial sand (free iron oxide content of the soil: 0.58%), and rice (cultivar:
Koshihikari) was subjected to a fertilizer effect test. Further, the same test was carried out also on the case where the converter residue was applied instead of the phosphate fertilizer of the present invention (control group). The results are shown in Table 7. In the case of using the phosphate fertilizer of the present invention, the iron content showed a three-fold or more higher absorption than the control group.

[0043]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a phosphate fertilizer according to the present invention (based on an analysis electron micrograph of Example 1).

FIG. 2 is an analytical electron micrograph showing the particle structure of the phosphate fertilizer shown in Example 1, wherein (A) is the same sample.
Indicates a gel-like silica component, the white part in the figure is gel-like silica, (B) indicates a phosphoric acid component, and in the figure, a white to gray part in the particle is a phosphoric acid component.

[Explanation of symbols]

 10: phosphoric acid component particles, 11: gel silica

[Procedure amendment]

[Submission date] May 26, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (9)

[Claims] 1. A quick-flow treatment comprising a water-soluble phosphoric acid and a c-soluble phosphoric acid as main components, wherein the phosphoric acid component is included in gel silica to prevent insolubilization and solidification of the phosphoric acid component. Slow release phosphate fertilizer. 2. A phosphoric acid content of 20% by weight or more, a gel silica content of 4.5 to 12% by weight, a phosphoric acid solubilization rate of 95% or more, and a water solubility of 35 to 65%. Item 1
Phosphate fertilizer according to claim 1. 3. An iron component and / or a magnesia component are contained together with a quo-soluble phosphoric acid and a water-soluble phosphoric acid, and the iron component and / or the magnesia component together with the phosphoric acid component or the phosphoric acid component are included in the gel silica. The phosphate fertilizer according to claim 1. 4. The phosphorus according to claim 3, wherein the phosphoric acid content is 20 to 35% by weight, the iron content is 20 to 32% by weight in terms of iron oxide, and the magnesium content is 1 to 16% by weight in terms of magnesium oxide. Acid fertilizer. 5. The phosphate fertilizer according to claim 4, wherein the content of the soluble magnesium component is 4 to 10% by weight in terms of magnesium oxide. 6. The phosphoric acid raw material is a phosphoric acid decomposition slurry,
By adjusting the acidity of the slurry to 1.4 to 1.8 and adding a powdery silicic acid raw material and granulating, the phosphoric acid fertilizer containing the phosphoric acid component by the generated gel-like silica is obtained. A method for producing a fast-releasing phosphate fertilizer, characterized by being produced. 7. The production method according to claim 6, wherein light clay is added as a viscosity modifier of the slurry to adjust the viscosity of the slurry to 2000 to 5000 cp, preferably 2700 to 4000 cp (80 ° C.). 8. A phosphoric acid ore or a heavy superphosphate lime used alone or in combination as a phosphoric acid raw material, and the phosphoric acid raw material is decomposed with sulfuric acid to form a slurry.
The production method described in 1. 9. A powdery magnesia material and / or an iron material material are added in the presence of a silicic acid material, and a phosphoric acid component or a phosphoric acid component and a phosphoric acid in which the magnesia component or iron content is included in the gel silica. The production method according to any one of claims 6 to 8, which produces a fertilizer.