WO2002066402A1 - Process for producing slow-release potassium fertilizer and slow-release potassium fertilizers - Google Patents

Abstract

It is intended to provide a process for efficiently producing a slow-release potassium fertilizer having excellent fertilizer characteristics and slow-release potassium fertilizers. That is, a slow-release potassium fertilizer is produced by the step 1 (ST1) of adding a potassium material to a starting material in a molten state containing one or more components selected form the group consisting of MgO, Al2O3 and FetO together with CaO and SiO2 wherein the ratio CaO/SiO2 is from 0.2≤CaO/SiO2≤1.0 and thus melting this potassium material and fusing it together with the molten material; the step 2 (ST2) of solidifying the fused mixture within the temperature region of 1000°C to 800°C at a speed of 0.5°C/min or more in case where CaO/SiO2<0.5 or at a speed of 5°C/min or more in case where CaO/SiO2≥0.5; and the step 3 (ST3) of grinding the solidified product thus formed.

Description

 Specification

 ^ ^ Method of sexual fertilizer and convulsive power

Leaking field

 The present invention relates to a method for producing a slow-release fertilizer and a slow-release fertilizer. Background thigh

 Fertilizers are indispensable for plant growth. Among them, nitrogen, phosphoric acid and potassium are fertilized as the three main components as they grow. Such fertilizers are applied to the soil, dissolved in irrigation and slowly absorbed from the plant roots.

 Among these fertilizers, potassium chloride and sulfuric acid are widely used as potassium fertilizers that supply potassium.All of them are water-soluble, so much of them flow away, and they contain salts such as chlorine and sulfuric acid. There were problems such as soil acidification and plant damage. For this reason, fertilizers that do not contain salts such as chlorine and sulfuric acid and can grow crops over a long period of time with a single fertilization, that is, fertilizers that gradually elute in soil and maintain long-term fertilization (slow-effect) Fertilizer) has been required. Conventionally, as a slow-release potassium fertilizer, a potassium-soluble fertilizer that is sparingly soluble in water but soluble in aqueous solution of citrate secreted from plant roots has been used. Such ku-soluble potassium fertilizer prevents runoff due to irrigation and increases its absorption as citric acid secreted from the root increases. Therefore, ideal slow release

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As a method for producing such a slow-acting potassium-soluble fertilizer, Japanese Patent Application Laid-Open No. 60-127286 discloses quartzite, blast furnace slag, nickel ore slag, phosphate slag, and andesite. After mixing powder and potassium raw materials such as potassium carbonate, this mixture The method of heating and melting is shown. In addition, Japanese Patent Application Laid-Open No. 55-17885 describes that after adding potassium raw materials such as potassium carbonate and caustic potash to fly ash collected by a dust collector of a lime-fired power plant, It discloses a method in which pulverized coal is added and granulated, and the granulated material is fired to cause a reaction between the potassium raw material and the fly ash composition.

 However, in the above-mentioned conventional techniques, a step of melting or firing is required when reacting the prepared raw materials, and an extremely large amount of heat is required for heating. However, there is a problem that the processing is lengthened.

 Therefore, as a method for producing a slow-acting potash fertilizer that solves such problems, Japanese Patent Application Laid-Open No. Heisei 9-28758568 discloses a method in which a potash material is added to molten slag on hot metal. There is disclosed a method of melting the molten slag with the molten slag, and cooling and solidifying the fused product. In this technique, since the potash raw material is fused to the slag already in a molten state, it has been disclosed in the above-mentioned Japanese Patent Application Laid-Open Nos. 60-1272886 and 555-151785. Compared with technology, the amount of heat required for heating is small and economical, and processing is possible in a short time.

By the way, in the technology disclosed in Japanese Patent Application Laid-Open No. 9-278568, although having the above-mentioned advantages, the conditions for efficiently producing a slow-release fertilizer having desired characteristics are considered. Is not shown. Also, with this technology, when cooling and solidifying a fusion product obtained by fusing raw material into molten slag on hot metal, it is granulated by wind milling or water milling, and the granulated material is used as a slow-release fertilizer. Attempts have been made to use it, but the shape of the grains is irregular and there are also angular grains. Is difficult to apply. It is conceivable to pulverize the granular material to eliminate such inconvenience.However, the pulverized material is liable to disperse the fertilizer during fertilization. This may impair the water permeability and air permeability of the ground. Disclosure of the invention

 An object of the present invention is to provide a method for producing a slow-release potash fertilizer that can efficiently produce a slow-release fertilizer having excellent fertilizer properties. In addition, a slow-release fertilizer that does not cause scattering during fertilization, runoff due to rainwater, and impairment of water permeability and air permeability of the ground does not occur, and that can provide a slow-release fertilizer that is easy to handle. It is intended to provide a production method and such a slow-release fertilizer.

 In order to achieve the above object, the first invention group provides the following three inventions.

(1) MgO, and Al ₂ 〇 _3, F e _t 1 kind selected from the group consisting 〇 or more components, the raw material melt containing the Ca_〇 and S I_〇 _2, addition of potassium raw material and, by melting this potash material fused with the raw material melt, a step of the value of Ca_〇 / S i0 ₂ forms a _{0. CaO / S i 0 2 ≤1} . melts is 0,

In the range from 1000 ° C to 800 ° C, the fused melt is 0.5 ° CZmin or more at Ca〇ZS iO ₂ <0.5 and Ca〇ZS i〇 ₂ ≥0.5. Is a process of cooling and solidifying at a temperature of 5 ° C / min or more, and

 Pulverizing the produced solidified product. A method for producing a slow-release potassium fertilizer.

(2) in the presence of molten metal, MgO, and Al ₂ 〇 _3, F e _t 1 kind selected from the group consisting of O or more components, the raw material melt containing Ca_〇 and S i 0 ₂ the object was added potassium raw material, to melt the potassium raw material are fused with a raw material melt, the value of CaO Roh S i0 ₂ is 0, 2≤C aO / S i 0 2 ≤ 1. 0 melt And the fusion-processed melt is taken out, and in the region from 1000 to 800 ° C, Ca〇 / S iO ₂ <0.5, at least 0.S ^ Zmin, CaO / S i In the case of 〇 ₂ ≥0.5, a step of cooling and solidifying at 5: Zmin or more,

Pulverizing the produced solidified product. Method of manufacturing the ingredients.

 (3) a step of adding a potash raw material into a hot metal holding vessel containing the hot metal subjected to the desiliconization treatment and the desiliconization slag generated during the desiliconization treatment of the hot metal,

A step of fusing at least the desiliconized slag and the potassium raw material to form a melt in which the value of C a〇ZS i〇 ₂ is 0. "2 ^ CaO / S i 0 ₂ ≤l.0,

In the range from 1000 ° C to 800 ° C, the slag produced by fusion is 0.5 ° CZmin or more for Ca OZS i〇 ₂ <0.5, and 5 for CaO / S i 0 ₂ ≥0.5. A step of cooling and solidifying at a rate of at least

 Pulverizing the produced solidified product. A method for producing a slow-release potassium fertilizer. .

According to the above configuration, a potash material is added to a predetermined molten material containing 〇 & pobi 3 i 0 ₂ , the potash material is melted and fused with the material melt, and the fusion process is performed. The molten material is cooled and solidified, and the resulting solidified material is pulverized to produce a slow-release fertilizer.When the molten material and the potassium material are fused, the basicity of the molten material is 0.2 ≤C aO / S i 0 ₂ ≤1.0 and 1000. In the region from C to 800, CaOZS i Os O. 5 in 0.5 Roh mi n or more, CaOZS I_〇 ₂ ≥0. 5 in 5 ° C / mi n or more, by a rate of cooling of the melt However, since a water-soluble compound can be produced by suppressing the production of a water-soluble compound, a slow-release fertilizer having excellent fertilizer characteristics can be efficiently produced.

 The second invention group provides the following three inventions.

(1) CaO, Mg_〇, the Al ₂ 〇 _3, F e _t 1 kind selected from the group consisting of O or more components of the raw material melt containing the S i 0 _2, was added potassium raw material Melting the potassium raw material and fusing it with the raw material melt;

 A step of cooling and solidifying the fusion-processed melt;

Crushing the solidified product, A step of adding a binder to the resulting milled material and granulating the resulting material, wherein the method comprises the steps of:

(2) in the presence of molten metal, Ca_〇, MgO, A l ₂ 〇 _3, Fe 1 kind selected group or al consisting _t 〇 or more components and S i0 ₂ raw material melt containing the Adding a potassium raw material, melting the raw material and fusing it with the raw material melt;

 A step of taking out the fusion-processed melt, cooling and solidifying; a step of pulverizing the generated solidified substance;

 A step of adding a binder to the produced ground product and granulating the produced product, comprising the steps of:

 (3) a step of adding a raw material to a hot metal holding vessel containing the hot metal subjected to the desiliconization treatment and the desiliconized slag generated during the desiliconization treatment of the hot metal,

 A step of fusing the desiliconized slag with the potassium raw material,

 A step of cooling and solidifying the slag produced by fusion;

 A method for producing a slow-release fertilizer, comprising: a step of pulverizing the generated solidified substance; and a step of granulating the generated pulverized substance by adding a binder.

According to the above configuration, CaO, Mg_〇, A l ₂ 〇 _3, Fe 1 kind selected group or al consisting _t 〇 or more components and S i0 ₂ raw material melt containing, Typically, a raw material is added to a molten slag, and the potassium raw material is melted and fused with the raw material melt to form a raw material compound. Excellent heat economy, enabling short-time treatment, and adding a binder to the ground material after grinding to granulate, so that it can be dispersed during fertilization, runoff by rainwater, and water permeability and air permeability of the ground. It is easy to handle because it is not regular and it is regular, spherical and not angular.

The third invention group provides the following two inventions. (1) A method for producing a slow-release fertilizer, comprising adding a binder to a potassium silicate raw material and granulating the raw material to obtain granular slow-release potassium fertilizer.

 (2) A slow-acting potassium fertilizer characterized by being granulated by adding a binder to a potassium gay acid raw material.

 According to the above configuration, the binder is added to the potassium silicate raw material and the granulation is performed.Therefore, scattering during fertilization, runoff due to rainwater, and impairment of water permeability and air permeability of the ground do not occur. A slow-release fertilizer with good handleability can be obtained because it is suitable, spherical and not angular.

 In the second invention group and the third invention group, as a result of studying a binder capable of satisfactorily granulating the above-described melt and having a particle size that is easy to handle, starch, magnesium sulfate, and I found that lignin is suitable. On the other hand, the slow-release potash fertilizer obtained by granulation has the hardness not to break the particles during handling from distribution to fertilization as well as during production, and the granular fertilizer has a moderate speed due to moisture in rain and soil. It is necessary to disintegrate and disperse in the soil. From such a viewpoint, starch is particularly preferable among the above binders. In other words, starch is gelatinized by adding water, and then hardened and solidified by drying. By using this property, the above-mentioned ground material can be granulated relatively easily, and the granulation efficiency is excellent. However, it is possible to obtain granules having sufficient hardness and good disintegration in soil and water. In addition, starch is decomposed by microorganisms in the soil, so it does not adversely affect plants and the environment. Therefore, starch is extremely preferred as the granulating binder.

When insufficient S I_〇 ₂ minutes in generating click-soluble potassium compounds molten slag as the raw material, rich silica sand, during coal combustion fly ash, the S I_〇 ₂ minutes, such as waste incineration ash Add substances and adjust ingredients.

Potassium raw materials include potassium carbonate, potassium bicarbonate, potassium sulfate, etc. Potassium-containing minerals such as feldspar can be used. If the potassium material to be added is, for example, potassium carbonate, it is melted and decomposed when added to the high-temperature raw material melt, and the reaction with the raw material melt is started. However, if the potassium raw material is potassium sulfate that is difficult to thermally decompose, it is better to charge the carbon material together with the potassium raw material, reduce the potassium sulfate in the melt, and change it to a form that is easily pyrolyzed.

In the present invention, as a raw material melt capable of producing a potassium-soluble potassium compound by reaction with a potassium raw material, a molten slag can be typically cited. There are blast furnace slag, converter slag, electric furnace slag, etc. that are discharged at the time. These slag S I_〇 _2, and C a O, M g O, on containing the components such as A 1 ₂ 〇 _3, F e _t O, since your digital is in the molten state, the molten state As soon as the potash raw material is added to the slag, the potash raw material is immediately melted and decomposed, and the reaction for producing the potassium-soluble potash compound is started. In particular, it is preferable to use desiliconized slag generated when the molten iron discharged from the blast furnace is desiliconized, as the slag that is the raw material melt. Desiliconization slag often S i 0 ₂ amount, by the addition of child potash material thereto, it is possible to generate a click-soluble force Li compound only auxiliary component adjustment. In addition, if potassium fertilizer is added to the desiliconized slag immediately after or during the desiliconization treatment, it is even more economical because the existing iron-making equipment can generate the quench-soluble compound. In the present invention, F e _t 〇 is a general term for iron oxide, but also includes any of the 6 0 Oyobi 6 ₂ 〇 _3.

BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a process chart showing a method for producing a slow-acting lipstick according to a first embodiment of the present invention.

 FIG. 2 is a process chart showing a method for producing a slow-release fertilizer according to a second embodiment of the present invention.

 FIG. 3 is a diagram showing an example of an apparatus for performing the fusion processing step in the first and second embodiments of the present invention.

 FIG. 4 is a diagram showing an example of an apparatus for performing a granulation step according to a second embodiment of the present invention.

 FIG. 5 is a diagram showing another example of an apparatus for performing a granulating step according to the second embodiment of the present invention.

 FIG. 6 is a process chart showing a method for producing a slow-release fertilizer according to a third embodiment of the present invention.

 FIG. 7 is a process chart showing a method for producing a slow-acting replenisher according to a fourth embodiment of the present invention.

 FIG. 8 is a diagram showing an example of an apparatus for performing a fusion treatment step and a fusion substance separation step in the third and fourth embodiments of the present invention.

 FIG. 9 is a plan view schematically showing an example of an apparatus for implementing the present invention using slag on hot metal discharged from a blast furnace.

 FIG. 10 is a cross-sectional view schematically showing an example of an apparatus for implementing the present invention using slag on hot metal discharged from a blast furnace.

 FIG. 11 is a diagram showing another example of an apparatus for performing the fusion treatment step and the compound separation step in the third and fourth embodiments of the present invention.

The first 2 figures maximum particle size and water rate of potassium carbonate (w- K ₂ 〇 / T one K ₂ 10 percent FIG.

FIG. 13 is Ru FIG der showing the relationship between potassium carbonate input rate and K ₂ 0 yield.

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be specifically described.

FIG. 1 is a process chart of a method for producing a slow-release fertilizer according to a first embodiment of the present invention. In this _{embodiment, MgO, A 1 2 0 3} , F e t and one or more components selected from the group consisting of O, the raw material melt, such as molten slag containing CaO and S I_〇 ₂ melted it by adding potassium raw material objects, components fused raw material melt (reaction) is allowed basicity C aO / S i 0 ₂ value 0. 2≤C aO / S i 0 ₂ to ≤ 1 . a fusion process ST 1 to obtain the melt of 0, in a temperature range of the fusion treated melt in the fusion process step ST 1 from 1000 ° C up to 800 ° C, C aOZS I_〇 ₂ ° 0.5 in 0. 5 ° CZmi n _{above, C aO / S i 0 2} ≥0. in 5 at 5 / mi n or more, the cooling and solidification step ST 2 to solidify by cooling at a rate of solidification, which is solidified by this process A slow-release fertilizer is produced by the crushing process ST3 for crushing the material.

In the fusion process ST 1, the value of salt Motodo C aO / S i 0 ₂ of the raw material melt and the melt and Chikarari material was fused _{0. 2≤C aO / S i 0 2} ≤1. 0 of The reason for setting the range is that if it is less than 0.2, CaO is too small and the slag properties deteriorate, and if it exceeds 1.0, the water-soluble compound increases and it does not become a slow-release fertilizer. Preferably from 0. 3 ≤C aO / S i O 2 ≤0. 7. In addition, an adjusting agent for adjusting the basicity other than the raw material melt and the potassium raw material may be added.

In the cooling and solidifying step ST 2, at a cooling rate of definitive a temperature range from 1000 ° C to 800, when the CaO / S I_〇 ₂ ° 0.5 is 0.5 ° C or more, CaOZS In the case of i O ₂ ≥0.5, the reason for selecting 5 "CZmin or more is that if the cooling rate is lower than this, water-soluble compound crystal will crystallize out, making it difficult to obtain a slow-release fertilizer. In particular, when CaOZS i〇 ₂ ≥0.5, crystals are easily formed, so a higher cooling rate is required. It is a temperature range where it is easy to generate.

In the first embodiment, as described above, a raw material is added to a raw material melt such as a molten slag, and the raw material is melted and fused with the raw material melt to form a power compound. It is excellent in heat economy and can be processed in a short time. In addition, it regulates the basicity and cooling rate of the melt obtained by fusing the molten raw material and the raw material, thereby suppressing the production of water-soluble compounds. total potassium (TK ₂ 0) water-soluble potassium for the proportion of (W- Κ ₂ 0) (water ratio _{WK 2 0 / TK 2 0 X} 100 ()) is 50% or less, preferably 25% or less fertilizer A slow-release fertilizer with excellent properties can be produced efficiently.

FIG. 2 is a process chart of a method for producing a slow-release fertilizer according to a second embodiment of the present invention. In this embodiment, CaO, MgO, and A 1 ₂ 0 _3, Fe ₂ 〇 one or more components selected from ₃ the group consisting of a raw material melt, such as molten slag containing S I_〇 ₂ A fusion processing step ST1 'for adding potassium raw material to the material and melting it, and reacting with the components of the raw material melt.Cooling for cooling and solidifying the fusion processed in this fusion processing step ST1' The slow-release fertilizer is obtained by the solidification step ST 2 ′, the pulverization step ST 3 ′ for pulverizing the solidified solidified in this step, and the granulation step ST 4 for granulating the pulverized matter in this step. To manufacture.

In the second embodiment, a raw material is added to a raw material melt such as molten slag, and the potassium raw material is melted and fused with the raw material melt to form a potassium compound. Excellent short-time treatment is possible, and binder is added to the crushed material after granulation, and granulation is performed. It does not impede water permeability or air permeability, and has good handling characteristics because it is regular, spherical and not angular.

In the fusion treatment step ST 1 ′, the basicity of the melt is not particularly limited, but is preferably set to 0.3 S CaOZS i 0 ₂ ^ 1.0 as in the first embodiment, and 0.3 ≤ CaO / S i O ₂ ≤0.7 is more preferred.

In the cooling and solidifying step ST 2 ′, the cooling rate is not particularly limited. However, as in the first embodiment, in the temperature range from 1000 ° C. to 800, CaO / SiO ₂ <0.5. Is preferably 0.5 ° CZ min or more, and Ca〇ZS i〇 ₂ ≥0.5, 5 and min or more.

In any of the first and second embodiments, the particle size of the raw material to be added to the molten raw material is preferably 1 to 25 mm. Scattered when added is less than 1 mm Shasuku, remaining K ₂ 0 remaining melted exceeds 25mm is alone, a water-soluble potassium (w -K ₂ 0) is increased. Further, it is preferable to supply the potassium raw material at a certain constant rate or higher. If the raw material supply is too small, the { ₂ } yield tends to be low. The total potassium (tau-kappa ₂ 〇) is not preferable to be 30% or less in ma ss%. If it exceeds 30%, the proportion of w—K ₂₀ increases.

 In the fusion processing steps SΤ1 and SΤ1 ', the raw material melt is charged into an appropriate container, the potash raw material is added to the raw material melt, and a composition and / or conditioning agent is added if necessary. Add to adjust the components of the melt. Also, if necessary, supplement the heat for melting the potassium raw material.

FIG. 3 is a diagram illustrating an example of an apparatus for performing the fusion processing steps ST 1 and ST 1 ′. In this figure, reference numeral 10 denotes a reaction tank, and reference numeral 50 denotes a raw material melt such as slag generated during steel refining. The reaction tank 10 can be hermetically closed by a lid 11, and a pressure state in the tank can be adjusted by a damper 13 provided in an exhaust gas duct connected to the gas outlet 12. In addition, a lid 11 is inserted through the reaction tank 10. Various lances are inserted therethrough. The lance 14 is for stirring the raw material melt 50, and is connected to a nitrogen gas pipe. The lance 15 is a lance for injecting potash material, the lance 16 is a lance for injecting the component adjusting agent, and the lance 17 is a lance for injecting the powder coke. These lances 15, 16 and 17 are respectively provided. Nitrogen gas piping is connected. A lance 18 is a lance (a lance for oxygen) for supplying oxygen gas or oxygen-containing gas. 20 is a potash raw material hopper, 21 is a component conditioner hopper, 22 is a powdered coke hopper, and these hoppers 20, 21, 22 are feeders 23, 24, 25, respectively. Have. A component adjusting agent supply system consisting of hopper 21, feeder 24, and lance 16, and a powder coke supply system consisting of hopper 22, feeder 25, and lance 17, and an oxygen gas supply system Is used as needed.

 In such an apparatus, first, the raw material melt 50 is charged into the reaction tank 10 and the charged amount is measured in advance. Next, a predetermined amount of potassium raw material with respect to the charged amount of raw material melt 50 is calculated and stored in hopper 20. In addition, a predetermined amount of the component adjuster based on the composition of the raw material melt 50 and the amount of the raw material melt 50 to be received is measured and stored in the hopper 21. Then, while blowing the nitrogen gas from the lance 14 to stir the raw material melt 50, the feeder 13 and the feeder 24 are activated to activate the potash material in the hopper 20 and the components in the hopper 21. The adjuster is extracted, and each is blown and transported with nitrogen gas, and then blown into the raw material melt 50 from the lances 15 and 16. The injected raw material melts, decomposes and dissolves into the raw material melt 50. The blown component adjuster also melts and dissolves into the raw material melt 50. At this time, the viscosity of the molten material is greatly reduced by the dissolution of the potassium raw material, and therefore, the stirring of the molten material becomes easier as the amount of the blown raw material increases. '

If the temperature of the raw material melt 50 drops significantly by charging the potash raw material and the component adjuster, start feeder 25 and load the coke breeze in hopper 22 I do. The coke breeze is pneumatically transported with nitrogen gas and blown into the raw material melt 50 from the lance 17. Simultaneously with the blowing of the powder coke, the blowing of oxygen gas or oxygen-containing gas is started from the lance 18 to burn the powder cogs in the raw material melt 50. The heat of combustion heats the melt and maintains that temperature. The coke breeze and the oxygen gas or the oxygen-containing gas are supplied at a controlled flow rate such that the temperature of the melt is kept within a predetermined range. Since the potash raw material reacts and evaporates with coke such as coke breeze, it is also effective to set the heating time with the kneaded flour and oxygen gas before the addition of potash.

 Even after the charging of the predetermined amount of the potash raw material and the component conditioner is completed, the stirring of the melt by blowing the nitrogen gas from the lance 14 is continued for a while, and the undissolved substance is left in the reaction tank 10. After making it absent, the fused material is discharged and sent to the cooling and solidification process. On the other hand, the exhaust gas is sent to an exhaust gas treatment device where it is degraded and released. If the raw material melt to be fused with the raw material does not require component adjustment, no component adjusting agent is charged.

The temperature of the raw material melt 50 decreases when the potassium raw material and the component adjuster are charged, but the melting point of the melt decreases due to a change in the composition due to the dissolution of the raw material. If is small, the melt is maintained in a stirrable molten state. For this reason, when the amount of potash material charged is relatively small, the blowing of the coke powder and oxygen gas or oxygen-containing gas may not be performed. The method of adding the potassium raw material, the component adjuster, and the coke breeze is not limited to the method of pneumatic transportation and blowing into the raw material melt 50, and the raw material melt 50 from the upper part of the reaction tank 10 is added. It may be a method of adding above. Furthermore, the powder coke can be burned simply by spraying on the raw material melt 50, so that the oxygen lance 18 is not immersed in the melt, and the oxygen gas or oxygen-containing gas is discharged from the raw material melt 50. It may be sprayed on 0. The method of cooling and solidifying the fusion melt in the cooling and solidifying step ST 2 and ST 2 ′ There is no particular limitation, and any method may be adopted. For example, a method in which high-pressure air is blown onto the fusion-processed melt to scatter and cool and granulate (cooling); a method in which high-pressure water is sprayed and scattered to cool and granulate; There is a method in which the molten slag is left in the air to be cooled and solidified.

 For example, the fusion-processed melt fed from the apparatus shown in FIG. 3 to the cooling and solidifying step is poured into a gutter, and high-pressure air is blown against the melt dropped from the gutter. The melt is scattered while falling and is cooled and granulated.

 The method of pulverization in the above-mentioned pulverization steps ST 3 and ST 3 ′ is not particularly limited, and any method may be employed. For example, there are jaw crushers, rod mills, fred mills, and inverable cars.

 The granulation method in the granulation step ST is not particularly limited, and a general granulation method can be employed.For example, the milled material obtained in the milling step and a binder are mixed with a mixer. After granulating with a granulator while spraying an appropriate amount of water, drying is performed.

As the granulator, a commonly used one, for example, a rotary dish type granulator, a rotary cylindrical type granulator, etc., can be adopted, and those which do not fall within a predetermined particle size range after granulation can be directly used. Alternatively, it is preferable to adopt a continuous granulation method in which the mixture is returned to the mixer after processing such as pulverization and reused as a part of the raw material. FIG. 4 is a diagram showing an example of an apparatus for performing the granulation step ST4. In this apparatus, the crushed material 90 obtained in the above-mentioned crushing step is loaded into a hopper 91 by a shovel loader or the like, and the weighed crushed material 90 is drum-typed from the hopper 91 through a conveyor 92. It is supplied to a rotary granulator 93. A predetermined amount of the binder 19 stored in the container 95 is also supplied to the drum-type rotary granulator 93, and by rotating the drum-type rotary granulator 93, the ground material 90 and the binder 9.4 are formed. Are mixed and granulated. After that, the granulated product is dried with a dryer 96, and the It is supplied to the sieve 98 by the sieve 97 and is sieved, and is further cooled by the cooler 99 to become granulated fertilizer. After cooling with a cooler, it can be sieved into granulated fertilizer.

 FIG. 5 is a diagram showing another example of an apparatus for performing the granulation step ST4. In this apparatus, the crushed material 100 obtained in the crushing step is charged into the hopper 101, and the weighed crushed material 100 is charged from the hopper 101 into the mixer 104. Also, a predetermined amount of the binder 102 stored in the container 103 is charged into the mixer 104. Then, the milled material 100 and the binder 102 are mixed in the mixer 104, and this mixture is supplied to the dish-shaped granulator 105, and is granulated in the dish-shaped granulator 105. You. The granulated product granulated by the dish granulator 105 is placed on a belt conveyor 106, and then dried by a drier 96 as in the apparatus shown in Fig. 4, and an elevator 9 It is supplied to the sieve 98 by the sieve 7 and sieved, and is further cooled by the cooler 99 to become granulated fertilizer.

 The binder used in the above granulation step is not particularly limited, and various kinds of binders such as phosphoric acid, clay, bentonite, PVA, CMC, polyacrylic acid, molasses, lignin, magnesium sulfate, starch, and mixtures thereof can be used. Lignin, magnesium sulfate, and starch are preferred in that they have good granulation properties and are easy to handle, and can be used alone or as a mixture of two or more of these. In addition, it is preferable that the particles have a hardness that does not destroy the particles during production and during handling from distribution to fertilization, disintegrate at an appropriate rate by moisture such as rain or soil, and disperse in soil. In particular, starch is preferred.

Examples of the starch used as a binder include those obtained from corn, evening pio, wheat, potato, rice and the like. Depending on the raw material, these starches are combined with amylose (d-glucose linked in a long linear form) as a component. It differs from the ratio of Ami-mouth pectin (d-glucose bound in a branched manner), and the ratio of Ami-mouth pectin is high in waxy rice and waxy maize. Further, the type of starch may be raw starch as it is, or modified starch treated with heat, acid, alkali, salt, enzyme or the like. Regardless of their type, starch having a gelatinizing property is suitable as a granulating binder.

Since starch is gelatinized by adding water and then hardened and solidified by drying, the raw material containing the above-mentioned pulverized material, i.e., Si ₂ and K ₂ , that is, the raw material of silica acid can be easily and efficiently produced. Can be granulated. By using starch as a binder in this way, it is possible to obtain a granular slow-release potash fertilizer having sufficient hardness and good decay in soil and water. In addition, starch is produced by microorganisms in the soil, etc., and does not adversely affect plants and the environment. Regarding the shape and particle size of the slow-release fertilizer thus granulated, the average particle size is preferably 0.5 to 6 mm. If the average particle size is less than 0.5 mm, it will be blown away by the wind during fertilization, making it difficult to handle. If the average particle size exceeds 6 mm, it will be difficult to spray uniformly. A more preferred particle size is 1 to 5 mm.

FIG. 6 is a process chart of a method for producing a slow-release fertilizer according to a third embodiment of the present invention. In the third embodiment, in the presence of molten metal is intended to fuse the raw material melt, such as potassium raw material molten slag, basically, _{Mg_〇, A 1 2 0 3, Fe} t 〇, and one or more components selected from the group consisting of, which was melted by the addition of potassium raw material raw material melt, such as molten slag you containing C A_〇 and S I_〇 _2, the raw material melt component fusion (reaction) is allowed to basicity CaOZS i0 ₂ values 0. 2≤CaO / S i 0 ₂ ≤1 things. fusion process ST 11 to obtain a melt of 0, Chikarari raw material and the raw material melt A fusion separation step ST12 to separate the fusion metal and the molten metal generated by fusion of the melts, and the separated melt is subjected to a Ca〇ZS i O in a temperature range from 1000 ° C to 800 ° C. ₂ <0.5 at 0.5 ° C min or more, CaOZS i 0 ₂ ≥0.5 at 5 ° C A slow solidifying fertilizer is produced by a cooling and solidifying step ST13 for cooling and solidifying at a speed of / min or more, and a crushing step ST14 for crushing the solidified material solidified by this step. In the fusion treatment step ST11, a regulator for adjusting the basicity may be added in addition to the raw material melt and the potassium raw material.

FIG. 7 is a process chart of a method for producing a slow-release fertilizer according to a fourth embodiment of the present invention. In the fourth embodiment, as in the third embodiment, a raw material such as a potassium raw material and a molten slag are fused in the presence of a molten metal. Basically, Ca〇, MgO _{, a 1 2 0 3, F} e t and one or more components selected from the group consisting of O, which was added to potassium raw material raw material melt, such as molten slag containing S I_〇 ₂ Fusion process step ST11 'for melting the molten metal and reacting with the components of the raw material melt, and a fusion product separation step for separating the molten metal generated by fusing the potassium raw material and the raw material melt with the molten metal

ST12 ', a cooling and solidifying step ST13' for cooling and solidifying the separated molten material, a pulverizing step ST14 'for pulverizing the solidified substance solidified in this step, and a pulverized substance pulverized in this step. The granulating process ST15 produces slow-release fertilizer.

In the fusion treatment step ST 1 1 ′, the basicity of the melt is not particularly limited, but is preferably set to 0.2 ≦ CaOZS i〇 ₂ ≦ 1.0 as in the third embodiment, 3 ≦ C aO / S i O ₂ ≦ 0.7 is more preferred. . Also, in the cooling and solidification step ST 13 ', there is no particular limitation on the cooling rate in the temperature range from 1000 ° C up to 800 ° C, as in the third embodiment, in CaOZS I_〇 ₂ ° 0.5 0.5 ° C / min or more, and Ca〇 / S i〇 ₂ ≥0.5, preferably 5 ° C / min or more.

In any of the third and fourth embodiments, as in the first and second embodiments, it is preferable that the particle diameter of the potash raw material added to the molten raw material is 1 to 25 mm. Also, the supply rate of potassium raw material should be 1 kgZmin or more per tonne of molten metal. Preferably, there is. At less than 1 kg / min per t of molten metal, the K20 yield tends to be low. Further, the total K ₂₀ (TK ₂₀ ) is preferably 30% or less in mass%.

 As in the third and fourth embodiments, when the raw material melt is fused with an additive such as a raw material, the presence of the molten metal reduces the amount of the potassium raw material and the component adjuster. Even in the case of a large amount, the molten metal can serve as a replenishing source of heat to suppress the temperature drop of the raw material melt as much as possible, and the fusion reaction can be caused while maintaining the required temperature.

 In the fusion processing steps ST11 and ST11 ', typically, the raw material is fused to the raw material melt while the raw material melt is suspended on the molten metal charged in an appropriate container. If necessary, adjust the components of the raw material melt by adding a component adjuster. In addition, when mixing the above raw materials, a carbon material such as powdered coke is added and an oxygen gas or an oxygen-containing gas is supplied to burn the carbon material and heat and melt the potassium raw material and the component conditioner. To reinforce heat.

 In the above-described fusion separation steps ST12 and ST12 ', after the fusion processing steps ST11 and ST11' are completed, for example, the fusion melt is separated from the molten metal by discharging the fusion melt from the container, for example. I do. On the other hand, the molten metal from which the fusion melt has been separated is sent to the next step or used in the next fusion treatment while remaining in the container.

FIG. 8 is a diagram showing an example of an apparatus for performing the fusion processing step ST 11 (ST 11 ′) and the fusion substance separation step ST 12 (ST 12 ′). In FIG. 8, the same portions as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In this example, a molten metal 51 is charged into a reaction tank 10 together with a raw material melt 50 such as a molten slag. A lance provided in the reaction tank 10, that is, a lance 14 for stirring the contents, a lance 15 for blowing the potash raw material 15, and a lance for blowing the component adjusting agent A lance 16 for blowing powder coke, a lance 17 for blowing coke, and a lance 18 for oxygen are inserted into the molten metal 51.

 In addition, a component adjusting agent supply system consisting of hopper 21, feeder 24, lance 16 and coke breeze supply system consisting of hopper 22, feeder 25, lance 17 and nitrogen gas supply system are necessary. Used according to.

 In such an apparatus, first, a raw material melt 50 such as a molten slag and a molten metal 51 are charged into a reaction tank 10, and the raw material melt 50 is suspended on the molten metal 51. At the same time, the charged amount of the raw material melt 50 is measured. Next, a predetermined amount of potash material with respect to the charged amount of the raw material melt is calculated and stored in the hopper 20. Further, if necessary, a predetermined amount of the component adjuster based on the composition of the raw material melt 50 and the amount thereof to be received is measured and stored in the hopper 21. Then, while feeding the nitrogen gas from the lance 14 into the molten metal 51 and stirring the raw material melt 50 and the molten metal 51 together, the feeder 23 and the feeder 24 are started to activate the hopper. The force in 20 The raw material and the component adjusting agent in the hopper 21 are extracted, transported by a stream of nitrogen gas, and blown into the molten metal 51 from the lances 15 and 16. The blown potassium raw material and the component adjuster are heated and melted by the molten metal 51 present in a large amount, and melt into the raw material melt 50.

As described above, the blown potassium raw material and the component adjuster are heated by the heat transfer from the molten metal 51, but by charging the raw material, the temperature of the molten material in the reaction vessel decreases. If the penetration is insufficient, start feeder 25 and charge coke breeze in hopper 22. The powdered coke is pneumatically transported with nitrogen gas and blown into the molten metal 51 from a lance 17. Simultaneously with the blowing of the coke powder, the blowing of oxygen gas or oxygen-containing gas is started from the lance 18 to burn the coke powder in the molten metal 51 or the raw material melt 50. The molten metal 51 and the raw material melt 50 are heated by this combustion heat, and the temperatures are maintained. powder Coke and oxygen gas are supplied at a controlled flow rate such that the temperature of the melt in the tank is maintained within a predetermined range.

 Even after the charging of the predetermined amount of the potash raw material and the component adjusting agent is completed, stirring of the melt by blowing nitrogen gas from the lance 14 is continued for a while, and there is no unmelted substance in the reaction tank 10. After it is in the state, a process is performed to separate the molten S and the molten metal, and the fused melt is discharged. The discharged fusion melt is sent to a cooling and solidifying device.

 On the other hand, the molten metal from which the fusion melt has been separated is sent to the next step, or is used in the next fusion treatment while remaining in the reaction tank 10. In the second and subsequent fusion processes, the same processing operation as above is performed after the raw material melt is charged. The lances 14, 15, 16, 17, and 18 in Fig. 8 are inserted above the molten metal 51 and into the raw material melt 50, and a bottom blow nozzle is provided at the bottom of the reaction tank 10 to send nitrogen gas. Alternatively, the raw material melt and the molten metal may be separately stirred. Further, the method of adding the potassium raw material, the component adjuster, and the powdered coke is not limited to a method of pneumatically transporting and blowing into the raw material melt 50, and the raw material is melted from the upper part of the reaction tank 10. It may be a method of adding it on the substance 50. Further, as in the case of the apparatus in FIG. 3, coke breeze can be burned simply by spraying on the raw material melt 50, so that the oxygen lance 18 is not immersed in the melt, and oxygen gas or oxygen is contained. Gas may be sprayed onto the raw material melt 50. The cooling and solidifying steps ST13 and ST13 ′, the pulverizing steps ST1.4 and ST14 ′, and the granulating step ST15 include the cooling and solidifying steps ST2 and ST2 ′ in the first and second embodiments. The pulverization steps ST3 and ST3 'and the granulation step ST4 are performed in the same manner.

The most practical hot metal should be used as the molten metal that is present when the process of fusing the raw material melt with the potash raw material is performed. 9 and 10 are diagrams schematically showing an example of an apparatus for carrying out the present invention using slag on hot metal discharged from a blast furnace. FIG. 9 is a plan view, and FIG. 10 is a sectional view. In Fig. 9 and Fig. 10, 30 is a main gutter for flowing molten iron slag discharged from the blast furnace, 31 is provided in the skinmer part, a weir for separating hot metal and blast furnace slag, and 32 is separated It is a slag gutter that allows blast furnace slag to flow down. A lance 35 for a potash raw material and a lance 36 for a component adjuster are provided at a position upstream of the weir 31 of the main gutter 30. In the main gutter 30, blast furnace slag 50a is in a floating state on the hot metal 51a, and the lance 35 is provided at or above the blast furnace slag 50a. The hot metal 51a is inserted to the depth to which it flows. One side of the nitrogen pipe is connected to a potash raw material supply device consisting of a potash raw material hopper 40 and a feeder 43, and the other is a component adjuster hopper 41 and a component consisting of a feeder 44. The regulator supply is connected. For this reason, the potash raw material and the component adjuster can be blown into the flowing molten iron slag.

 In such an apparatus, first, the flow rate value of the potash raw material and the flow rate value of the component adjuster calculated based on the expected flow rate and the expected composition of the blast furnace slag flowing down with the hot metal are fed to feeder-143 and feeder-144. Set each. While flowing molten iron slag, feeder 43, 44 is started while flowing nitrogen gas through each nitrogen pipe, and the potash raw material and the component modifier are blast furnace slag 50a or hot metal from lances 35, 36. Blow into 5 la. The blown potassium raw material and the component adjuster are heated and melted while flowing down together with the blast furnace slag 50a. The fused melt 52 in which the three raw materials of the potash raw material, the component adjuster, and the blast furnace slag are fused is separated from the hot metal 51a by a part of the skinmer, then diverted to the slag gutter 32, and sent to the cooling and solidifying device.

In this case, since the composition of the raw materials is calculated based on the expected value of the blast furnace slag flow rate, the components of the fusion-processed fusion melt fluctuate to some extent. For this reason, when it is necessary to strictly control the components of the product, the fused melt 52 diverted to the slag gutter 32 is charged into an apparatus as shown in FIG. When the raw materials are added It is better to perform the fusion process and adjust the components.

 Also in this example, the cooling and solidifying steps ST 13 and ST 13 ′, the pulverizing steps ST 14 and ST 14 ′, and the granulating step ST 15 are performed by the cooling and solidifying steps in the first and second embodiments. ST 2 and ST 2 ′, pulverization steps ST 3 and ST 3 ′, and granulation step ST 4 are performed in the same manner.

 In the above example, the third and fourth embodiments were implemented using blast furnace slag on hot metal that was tapped from a blast furnace, but desiliconized slag generated when the hot metal was desiliconized as a raw material melt was used. Is more preferable. At this time, it is preferable to add a potash raw material into a hot metal holding container that stores the hot metal that has been desiliconized and the desiliconized slag generated during the desiliconization of the hot metal. Hereinafter, an example of producing the slow-release potash fertilizer in this manner will be described with reference to FIG. FIG. 11 is a cross-sectional view schematically showing an example of an apparatus for performing the methods of the third and fourth embodiments using desiliconized slag on hot metal subjected to desiliconization. In FIG. 11, a ladle-type hot metal holding vessel 61 containing hot metal 62 from a blast furnace (not shown) is mounted on a bogie 63 and transported to a desiliconization treatment facility. The hot metal holding vessel 61 is transported from a blast furnace to a hot metal processing facility and a converter (not shown) by a bogie 63.

 The desiliconization equipment is equipped with an oxygen lance 66 and an injection lance 67. The top blown oxygen lance 66 and the injection lance 67 can move up and down in the hot metal holding vessel 61.

In addition, the desiliconization treatment equipment is a system consisting of storage tank 70 and lift tank 73, a system consisting of storage tank 71 and lift tank 74, and a system consisting of storage tank 72 and lift tank 75. It has a first raw material supply device 90 composed of the three raw material supply systems and a common dispenser 76, and the injection lance 67 is connected to the common dispenser 76. Then, the potassium raw material 65 stored in the storage tank 70, the component conditioner 68 stored in the storage tank 71, and the storage The slag-making agent 69 stored in the tank Ί2 can be blown into the hot metal 62 or the desiliconized slag 6 4 by adjusting the tip position from the injection lance 67 using nitrogen gas as a carrier gas. . In addition, by disposing the tip of the injection lance 67 directly above the desiliconized slag 64, the potash raw material 65, the component adjuster 68, and the slag-making agent 69 are mixed with nitrogen gas into the desiliconized slag 64. It can also be added by projection. The potash raw material 65 in the storage tank 70, the component adjuster 68 in the storage tank 71, and the slag-making agent 69 in the storage tank 72 are stored in the lift tanks 73, 74, and 75. Thus, the amount and time of addition can be independently controlled and blown, and only nitrogen gas can be blown from the injection lance 67 to stir the hot metal 62. The slag-making agent is used for adjusting the basicity at the time of the desiliconization treatment, and quick lime is generally used.

On the other hand, on the side opposite to the first raw material supply device 90, a hopper 77, 78, 79, a cutting device 81, 82, 83, a raw material conveying device 84, and a chute 85 are formed. A second raw material supply device 91 is provided, and the second raw material supply device 91 supplies the potassium raw material 65 in the hopper 77, the component adjuster 68 in the hopper 78, and the hopper 79. The iron ore sintered powder 80 can be placed in the hot metal holding vessel 61 and added. Next, a method for producing a molten slag having a desired slow-acting potash fertilizer composition using the desiliconization treatment equipment having such a configuration will be described. First, the method of manufacturing by adding potassium raw material 65 and component adjuster 68 after desiliconization treatment will be described. The hot metal 62 is desiliconized in the hot metal holding vessel 61, but the amount and composition of the hot metal slag (blast furnace slag) remaining in the hot metal holding vessel 61 is determined before the desiliconization processing. The amount of residual slag can be grasped by measuring the thickness of the slag or visually observing the area ratio of the residual slag covering the hot metal 62. The slag composition is determined by analysis. Next, a desiliconization treatment is performed. For example, the iron ore sintered powder 80 is added from the chute 85 into the hot metal holding vessel 61 and added. Oxygen gas is blown from the oxygen lance 66 to the surface of the hot metal 62, and nitrogen gas is blown from the injection lance 67 to mix the hot metal 62 and the iron ore sintered powder 80 with stirring. By this desiliconization treatment, oxygen gas and oxygen in the iron ore sintered powder 80 react with silicon in the hot metal 62 to form Si ₂ . S i 0 ₂ The generated mixed and fused with residual slag, S i 0 ₂ lots containing desiliconization slag 6 4 is generated on the hot metal 6 2. Note that the desiliconization treatment is not limited to such a method, and quick lime or the like may be blown as a slag-making agent 69 in an injection lance 67, and the iron ore sintered powder 80 Alternatively, iron oxide such as a mill scale can be used.

After this manner desiliconization process, grasp the S I_〇 ₂ amount produced by desiliconization treatment. The resulting S i 0 ₂ amount can the child understand the silicon concentration in the molten iron 6 2 before and after the desiliconization treatment. It can also be grasped from the total oxygen addition amount of oxygen gas and oxygen in the iron ore sintered powder. Then, the generation amount of S i 0 _2, in the amount and composition of residual slag after grasping prior desiliconization treatment, to grasp the approximate weight of the desiliconization slag 6 4. From the grasped approximate weight and approximate composition of the desiliconized slag 64, the amount of the potassium raw material 65 and, if necessary, the amount of the component adjuster 68 are determined. If an analytical sample is collected from the desiliconized slag 64 and subjected to component analysis, the correct weight and composition can be determined. Thereafter, a predetermined amount of potash raw material 65 and, if necessary, a predetermined amount of component adjuster 68 are added into the hot metal holding vessel 61, and the production of the fusion melt is started. It is desirable that nitrogen gas be blown into the hot metal 62 from the injection lance 67 before adding the potassium raw material 65. By injecting nitrogen gas, the hot metal 62 and the desiliconized slag 64 are agitated, and the desiliconized slag 64 is melted and the composition of the desiliconized slag 64 is made uniform, facilitating subsequent processes. This is because

The potash raw material 65 is preferably added from the chute 85 into the hot metal holding vessel 61 in order to improve the yield. At this time, pre-pot By doing so, the generation of dust can be prevented. In addition, when powdered potash raw material 65 is added, the carrier gas is used to inject into the desiliconized slag 64 from the injection lance 67, or to be injected into the desiliconized slag 64. It is preferable to add them. FIG. 11 shows a state where potassium raw material 65 is added on top. Although hot raw material may be blown into the hot metal 62, it is not so preferable because the yield of potassium raw material is reduced.

 It is preferable that the component adjuster 68 be blown into the pig iron 62 from the injection lance 67 in order to promote the melting of the component adjuster 68 and quickly obtain a desired slug composition. The order of addition of the potash raw material 65 and the component adjuster 68 is arbitrary, but a predetermined amount of the component adjuster 68 is added before the potash raw material 65, and then the addition of the potash raw material 65 is started. It is desirable to do. This is because the desiliconized slag 64 is adjusted to a predetermined component, so that the fusion of the potash raw material 65 and the desiliconized slag 64 is promoted, and the raw material 65 is maintained at a high temperature. This is because the period is reduced, the amount of evaporation of the power rim in the power raw material 65 is reduced, and the yield of the potassium raw material 65 is improved.

After the addition of the potash raw material 65 and the component adjuster 68, nitrogen gas is further blown into the hot metal 62 from the injection lance 67 to mix the desiliconized slag 64 with the potash raw material 65 and the component adjuster 68. It is preferable to promote fusion and to homogenize the composition of the generated molten slag. The potassium raw material 65 and the component modifier 68 added after the desiliconization treatment in this way are fused with the desiliconized slag 64 to produce a molten slag having a desired potassium-soluble potassium compound composition on the hot metal 62. You. Next, a method for producing a molten slag having a desired composition of a molten metal by supplying a potassium raw material 65 and a component regulator 68 during the desiliconization treatment will be described below. Before the desiliconization treatment, determine the amount and composition of the residual hot metal slag according to the above method. Then, desiliconization is performed in accordance with the above method. Add stabilizer 68 by injection lance 67 or shoot 85. In this case, the amounts of the potassium raw material 65 and the component modifier 68 are determined as follows. First, the amount and composition of residual slag before desiliconization treatment, with a generation of S I_〇 ₂ estimated from the difference between the target silicon concentration after desiliconization pretreatment of silicon concentration and desiliconization treatment, desiliconization The approximate composition and approximate weight of the desiliconized slag 64 generated by the treatment are grasped, and based on the grasped approximate weight and approximate composition of the desiliconized slag 64, the amount of the potassium raw material 65 added and, if necessary, In this case, the amount of the component adjuster 68 is determined.

 In this manner, the silicon removal treatment is performed for a predetermined time, and the operation is completed. The potassium raw material 65 and the component adjuster 68 added during the desiliconization treatment are fused with the desiliconized slag 64 to produce a molten slag having a composition with a high melting point compound on the hot metal 62.

 Also in this example, the cooling and solidifying steps ST 13 and ST 13 ′, the pulverizing steps ST 14 and ST 14 ′, and the granulating step ST 15 are the same as those in the first and second embodiments. Steps ST2 and ST2 ', pulverizing steps ST3 and ST3', and granulating step ST4 are performed in the same manner.

Thus, desiliconization slag often S i 0 ₂ amount, which in more adding potassium raw material, it is possible to produce a click-soluble potassium compounds only auxiliary component adjustment, yet existing steel equipment Therefore, it is more economical to use desiliconized slag as a raw material melt since a potassium-soluble potassium compound can be produced by the method. ,

(Example 1)

In the presence of hot metal discharged from the blast furnace of a steelworks, blast furnace slag in a molten state is fused with silica sand and carbon dioxide lime according to the process shown in Fig. 6, and molten raw materials with various basicities shown in Table 1 are produced. The fertilizer was produced and the cooling rate was changed as shown in Table 1 to produce a slow-release fertilizer. The fusion process was performed using the equipment shown in FIG. However, calcium carbonate was added by a projection method. As a result, as shown in Table 1, the value of basicity C aO-/ S I_〇 _{2 0. 2≤CaO / S i 0 2 ≤} 1. a 0, 800 ° from 1000 ° C during the cooling and solidification When the cooling rate in the temperature range up to C is 0.S ^ Zmin or more for CaOZS iC ^ O.5 and 5 ° CZmin or more for CaO / SiO ₂ ≥0.5, potassium water is dissolved. It was confirmed that the rate was low, the slag properties were good, and a slow-release fertilizer with excellent properties could be obtained.

(Example 2)

 The equipment shown in Fig. 8 was used to vary the particle size of potassium carbonate, which is a potassium raw material, in various ways to blast furnace slag and silica sand to produce a molten slag having the composition of No. 4 in Example 1. A slow-release fertilizer was produced according to the process shown in FIG. 1 by setting the cooling rate in the temperature range from 1000 ° C. to 800 ° C. during cooling and solidification to 5 ° C./min or more.

FIG. 12 shows the relationship between the maximum particle size of the carbon dioxide rim and the ratio of w—K _{20 at} that time. As shown in FIG. 12, it was confirmed that, when the maximum particle size of potassium carbonate as a potassium source was 25 mm or less, the water content of the potassium hydroxide was extremely low.

(Example 3)

By using the equipment shown in Fig. 8, blast furnace slag, silica sand, potassium carbonate with a particle size of 6 mm was used as the potassium raw material, and the charging speed of the carbon dioxide lime as the power source was varied in various ways. No. 5 molten slag was produced. A slow-release potash fertilizer was produced in accordance with the process shown in Fig. 1 by setting the cooling rate in the temperature range from 1000 ° C to 800 ° C during cooling and solidification at 5 ° C / min or more. Potassium raw materials were added by the projection method. The relationship between the carbonate force Riumu input rate and K ₂ 0 yield per hot metal 1 t at that time is shown in FIG 3. As shown in FIG. 1 3, the input speed of Chikararigen is that if the hot metal 1 t 1 k gZ min or more per are K ₂ 0 yield is maintained high was confirmed.

(Example 4).

 Using the blast furnace slag (hot metal slag), silica sand and potassium carbonate in the molten state shown in Table 2 discharged from the iron making process at the steelworks as raw materials, a slow-release potash fertilizer was produced according to the process shown in Figure 2. The fusion process was performed using the equipment shown in FIG.

 First, 100 parts by mass of blast furnace slag was charged into a reaction tank, and 39.3 parts by mass of silica sand and 57.6 parts by mass of potassium carbonate were mixed. At this time, oxygen gas was blown in while the coke powder was continuously added little by little so that the temperature of the contents in the tank was maintained at about 140 ° C. The addition of coke and the injection of oxygen gas prevented the temperature of the contents in the tank from dropping, and the silica sand and carbon dioxide lime were melted.

When all of the silica sand and carbonated lime fused with the blast furnace slag, the fused melt was discharged from the reactor, cooled and solidified. This fused solution In the cooling and solidifying treatment of the melt, high-pressure air was blown, scattered and cooled, and the above-mentioned melt was granulated by using a granulating device (crushing device).

 Next, the granular material was pulverized to a diameter of 1 mm or less, and 1.0 mass% of starch was added and mixed as a binder to the powder to adjust the water content. Next, the mixture is sized using a rotary dish granulator for testing, dehydrated and dried in a small box dryer at 100 ° C, and sieved to obtain a granulated product having a diameter of 1 to 5 mm. Obtained. When this granulated product was used as a fertilizer for actual use, it had an appropriate hardness as a fertilizer, and also had good flowability and good handleability. In addition, it was confirmed that scattering during fertilization, runoff by rainwater, and impairment of water permeability and air permeability of the ground were unlikely to occur.

On the other hand, as a result of analyzing the potassium and the silicic acid in the granular material before pulverization, the results are as shown in Table 3. In Table 3, T-K ₂ 〇 All Cali, c one kappa ₂ 〇 is click-soluble potassium ₍₂ 0 min kappa dissolved in 2% click E phosphate), w- kappa ₂ 0 indicates a water-soluble potassium. Furthermore, T -. S i 0 ₂ All silicate, s- S i 0 ₂ is soluble silicate (. 0 5 S i 0 ₂ min, dissolved in M hydrochloric acid) indicates to. As is clear from this table, among the potassium components contained in the granular material, very few were soluble in water, and most of them were soluble in potassium. That is, it was confirmed that the fertilizer of this example had excellent properties as a slow-release potassium fertilizer. In addition, it was confirmed that the above-mentioned granules contained a large amount of soluble silicic acid, and the fertilizer of this example could be used as a supply source of silicic acid. ,

(Example 5)

 Using desiliconized slag and carbonated lime in the molten state shown in Table 2 discharged from the hot metal pretreatment process at the steelworks as raw materials, slow-release fertilizer was manufactured according to the process shown in Figure 2. The fusion process was performed using the equipment shown in FIG.

First, 100 parts by mass of desiliconized slag was charged into a reaction tank, and oxygen gas was blown in while continuously adding coke breeze little by little, and the temperature of the contents in the tank was reduced to about 14.5. The temperature was set to 0 ° C. Thereafter, 41.3 parts by mass of potassium carbonate was continuously charged little by little, and the potassium carbonate was melted and fused with the desiliconized slag. Next, the melt subjected to the fusion treatment was discharged from the reaction tank, and the same operation as in Example 1 was performed to cool and solidify to obtain a granular material.

 Next, as in Example 4, the granular material was pulverized to a diameter of 1 mm or less, and 1.0 Omass% of starch was added and mixed as a binder to the powder to adjust the τΚ amount. Next, this mixture was sized using a rotary dish granulator for testing, dehydrated and dried in a small box-shaped dryer at 100 ° C, and sieved to obtain a granulated product having a diameter of 1 to 5 mm. . When this granulated product was subjected to actual use as a fertilizer, it had an appropriate hardness as a fertilizer and also had good fluidity, so that it was easy to handle. It was also confirmed that scattering during fertilization, runoff due to rainwater, and impairment of water permeability and air permeability of the ground were unlikely to occur.

 On the other hand, as a result of analyzing the potassium and the silicic acid in the granular material before pulverization, the results are as shown in Table 3. As is clear from this table, as in the case of Example 4, most of the potash content of the granular material of this example is soluble in potassium, and the fertilizer of this example is excellent as a slow-release potassium fertilizer. It was confirmed that it had the following characteristics.

(Example 6)

 In the presence of hot metal discharged from the blast furnace at the steelworks, the molten blast furnace slag shown in Table 2 is fused with silica sand and carbonated lime to produce slow-release fertilizer according to the process shown in Figure 7. did. The fusion treatment step and the fusion substance separation step were performed using the equipment shown in FIG.

First, 100 parts by mass of blast furnace slag and 400 parts by mass of hot metal are charged into a reaction tank, and while the slag is stirred by blowing nitrogen gas from a stirring lance, silica sand and potassium carbonate are successively added little by little. And 39.3 parts by mass of silica sand and 57.6 parts by mass of potassium carbonate were mixed. At this time, the coke breeze is added continuously little by little. Then, oxygen gas was blown in so that the temperature of the contents in the tank was maintained at about 140 ° C. The addition of coke and the injection of oxygen gas prevented the temperature of the contents in the tank from dropping, and the silica sand and carbon dioxide lime were melted.

 When all the silica sand and carbonic acid lime have fused with the blast furnace slag, the fused material is discharged from the reactor and separated from the hot metal, and the same operation as in Example 4 is performed to granulate the molten material. I let you go.

 Next, as in Example 4, the granular material was pulverized to a diameter of 1 mm or less, starch was added to the powder as a binder at 1% by mass, and the water content was adjusted. A granulated product was obtained in the same manner. When this granulated product was used as a fertilizer for actual use, it had an appropriate hardness as a fertilizer, and also had good fluidity and good handleability. In addition, it was confirmed that scattering during fertilization, runoff due to rainwater, and impairment of water permeability and air permeability of the ground were unlikely to occur.

 —On the other hand, the analysis of potassium and silicic acid in the granular material before milling resulted in the results shown in Table 3. As is clear from this table, as in the case of Example 1, most of the potash content of the granular material of this example is soluble in potassium, and the fertilizer of this example is excellent as a slow-release potassium fertilizer. It was confirmed that it had the following characteristics.

(Example 7) Here, first, the fusion treatment and the fusion substance separation step were performed using the equipment shown in FIGS. 9 and 10 described above. The composition of blast furnace slag was as shown in Table 2. The molten slag discharged from the blast furnace (slag ratio = 0.32 (slag hot metal t)) was flowed into the gutter at a flow rate of 20 t / h, and silica sand was added at a rate of 7.9 t. The potassium carbonate was blown at a rate of 11.5 tZ. The injected silica sand and potassium carbonate melted. After the molten iron slag into which the additive had been blown was received in a ladle, the fused melt was separated and sent to a cooling and solidifying device where it was solidified into granules. Then, as in Example 4, the granular material was pulverized to a diameter of 1 mm or less, and starch was added to the powder as a binder, and 1.0% by mass of the mixture was added and mixed to adjust the water content. To obtain a granulated product. When this granulated product was used as a fertilizer for actual use, it had an appropriate hardness as a fertilizer, and also had good fluidity and good handleability. In addition, it was confirmed that scattering during fertilization, runoff due to rainwater, and impairment of water permeability and air permeability of the ground were unlikely to occur.

 On the other hand, as a result of analyzing the potassium and the silicic acid in the granular material before pulverization, the results are as shown in Table 3. As is clear from this table, as in the case of Example 1, most of the potash content of the granular material of this example is soluble in potassium, and the fertilizer of this example is excellent as a slow-release potassium fertilizer. It was confirmed that it had the following characteristics.

 Table 3

(実施例 8)

(Example 8)

The present invention was implemented in the desiliconization treatment facility shown in FIG. Hot metal from the blast furnace was transported to a desiliconization facility. The hot metal weight is 150 t, the hot metal composition is C: 4.6 ma ss%, Si: 0.24 mas s%, P: 0.103 ma ss%, S: 0.042 ma ss%, and the hot metal temperature is 1395 ° C. The hot metal holding vessel, blast furnace slag as before E (CaO = 44mas s%, S I_〇 _{2 = 35mas s%, MgO =} 6ma ss%, A 1 2 0 3 = 13ma ss%) may remain, residual The amount of slag was 400 kg by visual observation.

First, desiliconization was performed. In the desiliconization process, the oxygen gas flow rate from the top-blown oxygen lance is set to 800 to 900 NmVr, and it is continuously sprayed onto the hot metal surface, and the iron ore sintered powder addition rate is continuously set at 200 to 240 kggmin. Then, quick lime as a slag-making agent was continuously blown into the hot metal with an injection lance at a rate of addition of 40 to 50 kg Zmin with a nitrogen lance, and the desiliconization treatment was completed in 5 minutes. The total amount of oxygen gas added was 74 Nm ³ , the total amount of iron ore sintered powder was 1100 kg, the total amount of quicklime was 220 kg, and the hot metal temperature after desiliconization was 1337.

Hot metal in the silicon concentration after desiliconization treatment becomes 0. 12 mA ss%, the S i 0 ₂ generation amount by desiliconization treatment was estimated from the silicon concentration in the molten iron before and after the desiliconization treatment with 385 kg. The basicity (C aO / S i 0) is calculated from the amount of residual slag 400 kg before the desiliconization treatment, the amount of quicklime added during the desiliconization treatment, 220 kg, and the amount of generated Si 0 ₂ 385 kg. ₂ ; also referred to as CZS) was estimated to be 0.75. From this basicity, it was not necessary to add a component adjuster. Potassium carbonate was used as the potassium raw material, the target for K ₂と し was 2 Omass%, the yield was 90%, and the amount of potassium carbonate added was calculated to be 409 kg. Next, production of a slow-release potash fertilizer was performed. First, before adding potassium carbonate, nitrogen gas was blown into the hot metal from an injection lance for 2 minutes, and the hot metal and the desiliconized slag were stirred and melted. Next, stop blowing nitrogen gas, and Potassium carbonate preformed into a briguet with a diameter was added at an addition rate of 80 to 120 kg / min, and the addition was continued for 5 minutes to complete the addition of 409 kg. After the addition of carbon dioxide lime, nitrogen gas was blown into the hot metal from the injection lance for 2 minutes to promote fusion of the desiliconized slag and carbon dioxide lime to obtain molten slag.

 After that, the generated molten slag was once discharged from the hot metal holding vessel into a steel ladle (Noropan) using a slag slag. Next, the molten slag was poured into an iron box provided in the building, cooled and solidified to obtain a lump slag of 12558 kg. This lump of slag was pulverized to a diameter of l mm or less, and 1.0 mass% of starch was added to the powder as a binder and mixed, and the amount of 7j was adjusted. Was. When this granulated product was used as a fertilizer for practical use, it had an appropriate hardness as a fertilizer, and also had good fluidity and good handleability. In addition, it was confirmed that scattering during fertilization, runoff due to rainwater, and impairment of water permeability and air permeability of the ground were unlikely to occur.

 Next, the composition of the slag before granulation and the yield of potassium carbonate were determined. Table 4 shows the slag composition and the yield of carbonated lime at that time, and Table 5 shows the analytical values of the water-soluble and water-soluble liquors.

As shown in these tables, it was confirmed that most of the power in the slag was soluble in slag and was excellent as a slow-release potassium fertilizer. The potassium carbonate yield was as high as 97%.

Table 4

 1258kg x 0.214

_{409kg x K 2 0 / K 2} C0 3 Table 5

(Example 9)

表 6に示すように、 バインダーとして硫酸マグネシウム、 リグニン、 デンプン を用いた No. 13, 14， 15の試料は、 優れた造粒性を有していることが確 認された。 その中でもデンプンは特に高い硬度を示した。 Potassium silicate fertilizer made mainly of steel slag is ground to a lmm diameter or less, a predetermined amount of the powdered potassium silicate fertilizer is weighed, and various binders shown in Table 6 are added and mixed to adjust the water content. The pellets were sized using a rotary dish granulator for testing, dehydrated and dried at 100 in a small box-type dryer, and sieved to obtain samples No. ll to No. 15 having a diameter of 1 to 5 mm. The granulation properties of these samples were evaluated, and the hardness was measured using a hardness meter. These results are also shown in Table 6. In addition, in the evaluation of the granulation property, the granulation property was evaluated as X because the samples of Nos. 11 and 12 could not be granulated. The granulation was evaluated as Δ because the samples of ~ 15 could be granulated. The hardness could not be measured for the samples of Nos. 11 and 12, which could not be granulated. Table 6

As shown in Table 6, it was confirmed that the samples of Nos. 13, 14, and 15 using magnesium sulfate, lignin, and starch as binders had excellent granulation properties. Among them, starch showed particularly high hardness.

(Example 10)

Powdered gay acid fertilizer made of steel slag as the main raw material is powder-framed to a diameter of 1 mm or less, a predetermined amount of this powdered fertilizer is added and mixed, and various starches shown in Table 7 are added and mixed. If the starch is not gelatinized while adjusting the water content, heat treatment is performed, sieved with a test rotating dish-type granulator, dehydrated and dried at 100 ° C in a small box dryer, and sieved. Samples Nos. 16 to 18 having a diameter of 1 to 5 mm were obtained. For these samples, the granulation properties were evaluated in the same manner as in Example 9, and the disintegration in water was evaluated. In the evaluation of underwater disintegration, 50 particles of the sample were allowed to stand in the water for 24 hours, and the number of undisintegrated particles was counted. Samples No. 17 and 18 that completely collapsed in water were evaluated as 〇. Table 7 shows the necessity of heat treatment during granulation, the evaluation results of granulation properties, and the evaluation results of disintegration in water. Also shown. Table 7

表 7に示すように、 No. 16-18の試料ではいずれも優れた造粒性および 十分な水中崩壊性を示したが、 加工デンプン Aおよび加工デンプン Bをバイン ダ一とした No. 17および 18の試料はより優れた水中崩壊性を示した。 また、 加工デンプン Bをバインダーとした No. 18の試料は加熱処理することなく造 粒することができた。

As shown in Table 7, the samples No. 16-18 exhibited excellent granulation properties and sufficient disintegration in water, but the modified starch A and modified starch B were the binders of No. 17 and No. Eighteen samples showed better underwater disintegration. In addition, No. 18 sample using processed starch B as a binder could be granulated without heat treatment.

(Example 11)

Ca-acid fertilizer made from steel slag as a main raw material is pulverized to 1 mm or less, a predetermined amount of the powdered ca-acid fertilizer is weighed, and starch is added and mixed at an addition rate shown in Table 8 to obtain a water content. Is adjusted with a rotary dish granulator for testing, dehydrated and dried at 100 in a small box type dryer, and sieved to obtain a sample of N 0.19 to 24 having 1 to 5 mm. Was. About the obtained sample, the hardness per grain was measured with a hardness meter, and the disintegration in water was evaluated in the same manner as in Example 10. These results are also shown in Table 8. Table 8

表 8に示すように、 No. 19〜 24いずれの試料においても高い硬度および 優れた水中崩壊性を得ることができたが、 デンプン添加率のより高い試料ではよ り高い硬度が得られていた。

As shown in Table 8, high hardness and excellent disintegration in water were obtained in all of samples Nos. 19 to 24, but higher hardness was obtained in samples with higher starch addition rate. .

In addition, the soil disintegration of the No. 19 sample was evaluated. For the evaluation of soil disintegration, 50 samples were added to 50 g of dry soil, mixed, added with a maximum volume of 60% water, and kept for 1 week. After that, it was passed through a sieve of 2000 zm and left standing in water overnight. As a result, more than 50% of the grains were disintegrated, and the hardness of the remaining grains was less than 0.1 kg, confirming that they had excellent soil disintegration properties. As described above, according to the present invention, a raw material is added to a predetermined molten raw material containing CaO and SiO ₂ , and the raw material is melted and fused with the raw material melt. solidified by cooling the melt is, defining the generated solidified product in producing a slow-release potassium fertilizer and Kona碎, the basicity of the melt to _{0. 2≤CaO / S i 0 2 1.} 0 At the same time, the cooling rate of the molten material in the temperature range from 1000 ° C to 800 is 0.S ^ Zmin or more for Ca〇ZS iO ₂ <0.5, and 5 ° CZmi for CaOZS i 0 ₂ ≥0.5. By setting it to n or more, the production of the water-soluble potassium compound can be suppressed and the potassium-soluble potassium compound can be produced, so that the fertilizer characteristics are excellent. A slow-release fertilizer can be produced efficiently.

Also, C A_〇, M G_〇, A l ₂ 〇 _3, F e _t 1 kind selected from the group consisting of O or more components and S I_〇 ₂ raw material melt containing, typically Adds potassium raw material to molten slag, melts the raw material and fuses it with the raw material melt to form a raw material compound. In addition to its excellent wettability, it can be processed in a short time, and the binder is added to the crushed material after granulation and granulated, so that it can be scattered during application, runoff due to rainwater, and impeded water permeability and permeability of the ground. No fertilizer is produced, and since it is regular, spherical and not angular, it is possible to obtain a slow-release fertilizer with good handleability.

 The binder is added to the raw material of potassium silicate and granulated.Therefore, there is no scattering during fertilization, runoff due to rainwater and impeded water permeability and air permeability of the ground, and it is regular, spherical and not square. A slow-acting potash fertilizer with good handleability can be obtained. In addition, good granulating properties can be obtained by using at least one of starch, magnesium sulfate and lignin as a binder.In particular, starch can be used during granulation, from distribution to fertilization. It has a hardness that does not break the particles during handling, disintegrates at an appropriate rate due to moisture such as rain or soil, and disperses in the soil, so it is possible to obtain a granular slow-release fertilizer with extremely good characteristics. it can.

Claims

The scope of the claims 1. MgO, the A 1 ₂ 0 _3, F 1 kind selected from e _t O made from the group or two or more minutes formed, the raw material melt containing CaO and S I_〇 _2, addition of potassium raw material and a step of forming the force re raw material is melted and fused with the raw material melt, CaOZS i0 ₂ values _{0. 2≤Ca O / S i 0 2} ≤1. melts is 0, In the range from 1000 ° C to 800 ° C, the fusion-processed melt is 0.5 ° C / min or more for Ca O / S i O ₂ <0.5, Ca〇_S iO ₂ ≥0 5. In step 5, cooling and solidifying at a rate of δ ^ Ζπιίη or more,  Pulverizing the generated solidified product. 2. in the presence of molten metal, MgO, A 1 ₂ 0 _3, F and one or more components selected from the group consisting of e _t 〇, raw material melt containing the Ca_〇 and S i0 ₂ in, it was added potassium raw material, the potassium raw material is melted and fused with the raw material melt, a C aO / S i 0 ₂ value _{0. 2≤C aO / S i 0 2} ≤1. 0 melt In the process from 1000 ° C to 80 O: in the range from 1000 ° C to 80 O: Ca〇 / S i O ₂ <0.5, more than 0.S ^ min, CaOZS In the case of iO ₂ ≥0.5, the method comprises a step of cooling and solidifying at a rate of 5 min or more, and a step of pulverizing the generated solidified product. Manufacturing method. 3. The method for producing a slow-release potassium fertilizer according to claim 2, wherein the molten metal is hot metal. 4. The method according to claim 1, wherein the raw material melt is molten slag. 4. The method for producing a slow-release potassium fertilizer according to any one of claims 3 to 4. 5. The method for producing a slow-release fertilizer according to claim 4, wherein the molten slag is a desiliconized slag generated when desiliconizing hot metal discharged from a blast furnace. 6. adding a raw material into a hot metal holding vessel containing the hot metal subjected to the desiliconization treatment and the desiliconization slag generated during the desiliconization treatment of the hot metal; Forming at least desiliconization slag and the potassium raw material are fused value of C aO / S i 0 ₂ and is _{0. 2≤CaO / S i 0 2 ≤1} . Melts is 0, In the range from 1000 ° C to 800 ° C, the slag produced by fusion is 0.5 ° CZmin or more for C aO / S i O ₂ <0.5, and C aO / S i 0 ₂ ≥0.5 In the process of cooling at 5 ° C 7 min or more at a speed of solidifying,  Pulverizing the produced solidified product. A method for producing a slow-release fertilizer. 7. The slow-release effect according to any one of claims 1 to 6, further comprising a step of adding a binder to the pulverized material produced by pulverization and granulating. A method of manufacturing fertilizer. , 8. CaO, MgO, to _{A 1 2 0 3, F e} t 1 kind selected from the group consisting of O or more components and S I_〇 material melt containing _2, was added potassium raw materials, Melting the potassium raw material and fusing it with the raw material melt;  A step of cooling and solidifying the fusion-processed melt;  Crushing the solidified product, Adding a binder to the generated pulverized material and granulating it. A method for producing a slow-release fertilizer. 9. In the presence of molten metal, CaO, MgO, to _{A 1 2 0 3, Fe t} 1 or was exposed, selected from the group consisting of O or more components and S I_〇 material melt containing _2, Adding a potassium raw material, melting the raw material and fusing it with the raw material melt;  A step of taking out the fusion-processed melt, cooling and solidifying; a step of pulverizing the generated solidified substance;  A step of adding a binder to the generated milled material and granulating the milled material, the method comprising the steps of: 10. The method for producing a slow-release potassium fertilizer according to claim 9, wherein the molten metal is hot metal. 11. The method for producing a slow-release fertilizer according to any one of claims 8 to 10, wherein the raw material melt is a molten slag. 12. The method for producing slow-release potassium fertilizer according to claim 11, wherein the molten slag is a desiliconized slag generated when desiliconizing hot metal discharged from a blast furnace. 13. a step of adding a raw material into a hot metal holding vessel containing the desiliconized hot metal and the desiliconized slag generated during the desiliconization of the hot metal;  A step of fusing the desiliconized slag with the potassium raw material,  Cooling and solidifying the slag produced by fusion; A step of pulverizing the generated solidified matter, A step of adding a binder to the generated milled material and granulating the milled material, the method comprising the steps of: 14. The slow-release effect according to any one of claims 7 to 13, wherein the binder is mainly composed of at least one of starch, magnesium sulfate and lignin. Manufacturing method of fertilizer. 15. The buffer according to any one of claims 7 to 14, wherein the binder is added in a ratio of 0.5 to 6 mass% with respect to the pulverized material. Production method of potash fertilizer. 16. The method for producing a slow-release fertilizer according to any one of claims 1 to 15, wherein the particle diameter of the potassium raw material is 1 to 25 mm. 17. The feed rate of the raw material is 1 kgZmin or more per 1 t of molten metal, and any one of claims 2 to 7 and claims 9 to 16 Or the method for producing a slow-release fertilizer according to item 1. 18. A method for producing a slow-release fertilizer, comprising adding a binder to a potassium gay acid raw material and granulating the raw material to obtain granular slow-release potassium fertilizer. 19. The method for producing a slow-release potash fertilizer according to claim 18, wherein the binder mainly comprises at least one of starch, magnesium sulfate, and lignin. 20. The slow-release potassium fertilizer according to claim 18 or claim 19, wherein the binder is added at a ratio of 0.5 to 6 mass% with respect to the raw material of the silicate acid. Production method. 21. A slow-release potash fertilizer characterized by being granulated by adding a binder to the potassium silicate raw material. 22. The slow-release fertilizer according to claim 21, wherein the binder is mainly composed of at least one of starch, magnesium sulfate and lignin. 23. The slow-release potash fertilizer according to claim 21 or claim 22, wherein the binder is added at a rate of 0.5 to 6 mass% with respect to the potassium silicate raw material.