KR910009598B1 - Granular potassium sulfate and its production - Google Patents

Abstract

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Description

Granular potassium sulfate and its manufacturing method

1 to 3 are working system diagrams of the apparatus used in the method of the present invention.

This invention relates to granular potassium sulfate and its granulation method. More specifically, the present invention relates to granular potassium sulfate formed by wet granulation after adding a predetermined amount of neutralizing agent such as calcium hydroxide to modified potassium sulfate containing unreacted sulfuric acid powder, and a granulation method thereof.

In general, granulation of fertilizers in recent years has been implemented to improve fertilization workability and machine fertilization. In particular, in recent years, mechanical fertilization has become widespread, and a good commodity having good fluidity with respect to potassium sulfate has been strongly desired. In recent years, granulated single fertilizers have been used for mass-blended fertilizers that are widely spread. Therefore, various fertilizers are currently granulated in a method suitable for their physical properties and are provided to the market.

There is also a demand for a potassium sulfate as a potassium fertilizer raw material. However, regarding the granulation of potassium sulfate, there are various manufacturing and quality problems as described below. For example, in the wet granulation method in which 5 wt% or more of water is mixed with the raw material potassium sulfate, it is difficult to obtain a product having a desired particle size range with good efficiency because of poor assembly of potassium sulfate.

When granular potassium sulfate obtained by compression granulation of potassium sulfate-water mixture with a roll press or the like is used as the raw material for the bulk compounding fertilizer described above, the granular potassium sulfate portion is differentiated during the handling and transportation of the obtained bulk compound fertilizer. ), And the classification of the bulk compound fertilizer occurs, the segregation of the ineffective components according to the particle size becomes a problem.

Therefore, 6-12 mesh granular potassium sulfate is generally used as a raw material of a compounding fertilizer or a mass compounding fertilizer. In such a use, the granular potassium sulfate obtained by the above-mentioned compression granulation method has to go through the process of classifying into a sieve after compression disintegration, so that the surface has many protrusions and the compressive hardness is relatively high, but the damaged surface is worn out. easy. Thus, during the handling and transportation of this assembly with flow, differentiation occurs from the fragile side of the individual particles.

As a raw material of the bulk compound fertilizer, potassium sulfate, which is compression-assembled by roll-press by a conventional method, is used, but its differentiation rate is about 10%, which is remarkable compared to the average differentiation rate of other granular fertilizers 2-3%. There are many. Therefore, granular potassium sulfate is being sieved again before mass mixing, and thus, a merchandise that does not need to be sieved again is desired.

The inventors of the present invention have conducted various studies to obtain a preferred potassium sulfate product as described above, and after adding a predetermined amount of a neutralizing agent such as calcium hydroxide to a modified potassium sulfate containing unreacted sulfuric acid, it is wet granulated to solve the above problems. Knowing this is solved, the present invention has been completed.

As is evident from the above description, it is an object of the present invention to provide a granulation method of potassium sulfate having extremely low differentiation rate and good fluidity, and granular potassium sulfate granulated by the method.

This invention (2 invention) has the main component of following (1) and (2) and embodiment structure of (3)-(8).

(1) 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, and oxidation to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. Granulated potassium sulfate formed by wet granulation with magnesium, magnesium carbonate or ammonia.

(2) 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, and oxidation to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. A granulation method of granular potassium sulfate, characterized in that wet granulation is added to magnesium, magnesium carbonate or ammonia.

(3) 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. Or granular potassium sulfate formed by compression molding by adding at least one powdered neutralizing agent selected from magnesium carbonate and wet granulation of the powder obtained by pulverizing the molded article.

(4) 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, and oxidation to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. A method of producing granular potassium sulfate, characterized by compression molding by adding at least one powdered neutralizing agent selected from magnesium or magnesium carbonate, pulverizing a molded article, and then wet granulating with a wet granulator.

(5) The method according to 4, wherein the compression molding is performed by a roll-press, a solid machine, an extruder, or a granulator.

(6) The method according to claim 4, wherein the wet granulation is performed by a dish granulator, a drum granulator or an extruder.

(7) The method according to claim 4, wherein water, aqueous potassium sulfate solution or potassium sulfate slurry is added so that the granulated water (moisture in undried wet granulation) at the time of wet granulation is 2 to 20% by weight.

(8) The method according to claim 4, wherein the wet granulated product is classified after drying to obtain granular potassium sulfate, and the oversize product is pulverized, but the undersize product is not pulverized or pulverized and circulated by a wet granulator.

As potassium sulfate, preferably powdered potassium sulfate used in the present invention, modified potassium sulfate obtained by dry reaction of potassium chloride and sulfuric acid is preferably used.

However, potassium sulfate obtained by other methods can of course also be used.

The degree of powder separation of the raw material potassium sulfate, that is, the particle size is not limited. It can be used for this invention as long as it is the grade used as a raw material for a squeezing normally, or the grade which can fully perform wet neutralization.

That is, the form is preferably, for example, a powder such as 20 mesh (Dier-, the same below) pars, and granulation such as 5 meshion is not preferable. The use of granules, such as 5 mesion, results in incomplete wet neutralization and diminishes the effect of the present invention. In other words, it can be seen that the wettability of the granulated product deteriorates, the acquisition rate of the incoming products decreases, and the hardness (compression breaking pressure) of the obtained incoming products decreases.

As the neutralizing agent used in the present invention, if unreacted sulfuric acid in modified potassium sulfate and reactable at 0 to 200 ° C, the product after the reaction (sulphate) does not adversely affect the potassium sulfate as an inactive ingredient. Can be used.

Specifically, at least one powder phase compound or ammonia selected from calcium or magnesium compounds such as calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide and magnesium carbonate is preferably used.

The amount of the powdery compound used is 0.5 to 2.0 times equivalents, preferably 0.8 to 1.5 times equivalents relative to the unreacted sulfuric acid content in the modified potassium sulfate previously determined. If less than 0.5 equivalent, the acidity of potassium sulfate after neutralization becomes high (low pH), which is unsuitable as a mass fertilizer, and if it exceeds 2 equivalents, the concentration of inactive ingredient (K ₂ O min) in potassium sulfate after neutralization is increased. It is not preferable because it is lowered.

The amount of ammonia used as a neutralizing agent in the present invention is 0.5 to 1.2 times equivalents, preferably 0.8 to 1.0 times equivalents, relative to the unreacted sulfuric acid content in the unneutralized potassium sulfate. If less than 0.5 equivalent, the acidity of potassium sulfate after neutralization becomes high (low pH), and it is unsuitable as a mass compound fertilizer, and more than 1.2 times equivalent is a large amount of unreacted ammonia, and it is volatilized and recovered at the time of drying. This is not desirable because it becomes complicated. Ammonia is usually used in aqueous solution or gas phase.

In the above-mentioned embodiment (4) of the present invention, water is not used at the time of neutralization. The method for mixing and neutralizing the neutralizing agent and the modified potassium sulfate is not limited. That is, for example, a predetermined amount of the powder of neutralizing agent is added at a time or gradually, while mixing or modifying the granular modified potassium sulfate in a known rotary or stirred mixer in a short time (e.g., within 30 minutes). Be sure to In order to prevent the neutralizing agent from adhering to the wall in the mixer or to the part of the modified potassium sulfate, the neutralizing agent diluted by mixing the entire amount of the neutralizing agent and a part of the modified sulfuric acid may be used in the above mixing process.

In addition, since the above-described neutralization step usually contains a very small amount (for example, 0.1% by weight) of water contained in the modified potassium sulfate and the neutralizing agent, the neutralization step does not proceed simultaneously with the above-described mixing step. That is, in accordance with the progress of the process such as compression molding and grinding and wet assembly, in other words, it proceeds over time and is substantially finished at the end of assembly.

Compression molding is carried out by a compression molding machine such as a roll press, a blender, an extruder or a granulator. Although the conditions for compression molding are not limited, it is preferable to select so that the object to be compressed is sufficiently molded.

The shape of the compression molded product obtained in this way is not the same as a platelet shape, a gram shape, a rod shape, or a tablet shape, depending on the type of the compression molding machine used. It is crushed to a particle size. The kind and grinding conditions of the grinder to be used are not limited as long as the particle size mentioned later is obtained. For example, a bowl mill, a roll mill, etc. are used. Grinding is carried out continuously at room temperature to 50 ° C or in the case of batch method at room temperature to 50 ° C for 5 minutes to 5 hours, preferably 10 minutes to 3 hours.

The degree of powdering, ie, the particle size, of the compressed molded article after grinding is not limited. Generally, as a raw material of wet granulation, it is preferable to grind | pulverize finely, for example to about 100 mesh parses or less.

The powdered neutralized powder thus obtained is wet granulated by a granulator of the following step. In the above-described embodiment (4) of the present invention, the wet granulation step of the present step is effectively performed through the above-described mixing, compression granulation, and grinding steps.

The amount of water used for the wet neutralization of the method of the above-described embodiment (10) or (15) of the present invention is not limited.

What is necessary is just enough to neutralize. Usually, it is 2 to 20 weight% (same as wet basis or less) with respect to modified potassium sulfate, Preferably it is 4 to 15 weight%. At 2 wt% or less, neutralization may not proceed sufficiently to reduce the effect of the present invention. Moreover, when it exceeds 20 weight%, energy for drying becomes large and it is uneconomical.

The mixing method of the modified potassium sulfate, the neutralizing agent, and water is not limited. For example, the above three kinds of mixed raw materials may be added simultaneously or subsequently in an open or closed mixer to be mixed for 1 minute to 1 hour, preferably 5 minutes to 30 minutes at 0 to 100 ° C, preferably 20 to 80 ° C. . However, to the extent that the effects of the present invention are not impaired, only modified potassium sulfate and a neutralizing agent may already be mixed, and the mixture may be fed together with water to a wet granulator to proceed with neutralization. The supply ratio of water is possible in the range of 0.5 or less by weight with respect to the neutralized potassium sulfate supplied to a wet granulator. In this way, the drying step of the neutralized product can be partially omitted in the two drying steps during the entire process from the raw material to the production.

The above-mentioned mixer is not limited as long as mixing of the same thing as the main body is possible in a short time, and for example, a molding blender with a stirrer, a ribbon blender, or the like can be used.

The wet granulation is usually carried out by a motorized granulator such as a dish granulator, a drum granulator, or an extruder, but is not limited thereto.

The amount of water added to the potassium sulfate supplied in the wet granulation is not limited. Water in the assembly immediately after assembly (assembly moisture, the same below) is different depending on the model of the granulator and the particle size of the potassium sulfate supplied, but usually from 2 to 20% by weight (based on wet products, the same below), preferably 4 to 15 Weight percent.

As the granulated water, water, an aqueous potassium sulfate solution or a potassium sulfate slurry can be used.

Other compounds may be contained in the granulated water as long as they do not interfere with the assembly of potassium sulfate.

Potassium sulfate, assembled with a wet granulator, is dried in a dryer. Although the kind and drying method of a dryer are not limited, In order to reduce the differentiation during drying, it is preferable to take mild conditions.

As long as the effect of this invention is not impaired, the drying of a wet neutralization product and a wet assembly may also use the same drying. Prior to this drying, the assembly conditions described above should be chosen to allow sufficient neutralization of the wet assembly. Because, in the method of the present invention, the neutralization reaction does not necessarily proceed to the necessary and sufficient degree only by the first wet neutralization of modified potassium sulfate, and the neutralization is first performed in the step of receiving wet granulation through the grinding process after the wet neutralization product. This is because there are many cases where it proceeds sufficiently.

The merchandise obtained as described above is sieved and classified in the order of the oversized product, the product and the undersized product in the order of particle diameter.

The oversize article is crushed by a grinder and circulated in the wet granulator, and the undersize article is crushed or crushed and circulated in the wet granulator. Whether or not the undersized product is crushed is determined by the particle size balance of the whole potassium sulfate supplied to the wet granulator.

In the two use processes of the dryer, when the same dryer is used, the wet neutralized product is present in the above-mentioned undersized product. The progress of neutralization of the oversized product is usually sufficient, and it can be replaced by crushing the wet neutralized dry product and supplying it to the wet granulator by pulverizing and supplying it to the wet granulator.

The above process is demonstrated with reference to FIGS.

In FIG. 1 according to the above-described embodiment (4) of the present invention, the modified potassium sulfate and the neutralizing agent supplied from the pipe 1 and the pipe 2 are mixed (not shown in the mixer), and the Hopper-A via the pipe 3 Stored in and supplied to Compressor B. The press-molded article compression-molded in B is sent to the grinder C via the pipe 4, crushed, and then supplied to the wet granulator D together with the circulated product (described later) via the bucket 5 lever.

In D, granulated water is sprayed from the pipe 6 to form powdered and non-granular potassium sulfate and a wet granular product, which is sent to the dryer E via the pipe 7. The incoming merchandise dried at E is sent to sieve F via a basket 8 on the basket. At this time, the merchandise is classified as oversized, products and undersized in order of size and size.

Thus, the oversized product is sent to the grinder G via the pipe 9 and ground.

The product is taken out of the piping 11 outside the system. At least the oversized pulverized articles and the undersized articles are drawn out from the pipes 10 and 12 and circulated to D via the flow-conveyor 13.

In FIG. 2 relating to the above-described embodiment 10 of the present invention, the modified potassium sulfate and the neutralizer supplied from the pipes 1 and 2 are supplied to the mixer A via the pipe 3. In the mixer, water is sprayed from the pipe 16, three raw materials are mixed, and the neutralization reaction proceeds. The mixture which has undergone neutralization is sent to dryer E together with the wet assembly sent via pipe 5 and via pipe 7 (dryer combined). Potassium sulfate dried at E is sent to Sieve F via a vacetterlever 8, and it is classified in order of oversize goods, products, and undersize goods from F to particle size.

The oversized product is sent to the grinder G via the pipe 9 to be ground.

The product is drawn out of the system from the pipe 11.

The undersized product is sent to the grinder H via the pipe 15 to be crushed or sent intact in the pipe 14 without being crushed.

Potassium sulfate other than these products (note, over or undersized product after grinding | pulverization, an unpulverized undersize product) is circulated by the wet granulator D via the flow conveyor 13 and piping 13 '.

In D, about 50 weight% or less of water is sprayed on potassium sulfate from piping 6, and granulation is performed.

The undried granular potassium sulfate wet-assembled as mentioned above is sent to the above-mentioned drier E via piping 7 as mentioned above, and is dried simultaneously with potassium neutralized sulfate (main | wet neutralization goods) from the mixer A.

In FIG. 3 according to the above-described embodiment (4) of the present invention, the modified potassium sulfate pulverized in advance from the pipe 1 is supplied to the wet granulator D from the pipe 13.

On the other hand, the ammonia water is supplied from the pipe 2 to D, and granulation is performed. The wet goods are sent to the dryer E via the pipe 7, and the goods dried at the E are sent to the sieve F via the bucket elevator 8.

In this sieve, the merchandise is classified into oversized, products and undersized in the order of size and size. In addition, the oversized product is sent to the crushing G via the pipe 9 to be crushed.

The product is taken out of the pipe 11 out of the system.

The undersized product is sent to the grinder H as it is from the pipe 14 or via the pipe 15, and pulverized, and the crushed product is taken out from the pipe 12 and circulated to the wet granulator via the flow-conveyor 13 and the pipe 13 '.

The first effect of the present invention is that the hardness of the obtained product is high and the rate of differentiation is low.

That is, as apparent from Examples 1 to 2 and Comparative Examples 1 to 4 to be described later, the hardness (compression failure pressure) of the incoming goods obtained by the present invention is 4 to 7 as the particle size of the mesh (dier-). As much as 6 kg, the differentiation rate is 3 to 5% by weight, and it is clear that a remarkable difference occurs in hardness and differentiation rate compared with the conventional products.

The second effect of the present invention is that the shape of the obtained product is good (conceived) and the fluidity is good.

Therefore, the incoming goods obtained by the present invention are suitable for machine fertilization.

The third effect of the present invention is that the granulation of the powdered product in the wet granulation is extremely good and the yield of the product is good. That is, since the yield of a product is good, the circulation amount with respect to a product quantity becomes small, and it is possible to miniaturize a facility.

In addition, with respect to the above-described embodiment (4) of the present invention, as apparent in Examples 1 to 3 and Comparative Examples 1 to 3 described later, the number of granules to be used in wet assembly is further reduced by compression molding. The trend is seen.

The reason is not clear, but it is estimated that, as a result of the compression, the density of the particles increases and the particle surface area (specific surface area) per unit weight decreases.

The reduction of the granulated water gives an energy saving effect along with the miniaturization of the equipment described above.

The invention is illustrated by the following examples and comparative examples.

Example 1

解機)에 상기 해쇄품 500g를 넣어, 30분간 분쇄하여 시료로 한다.Pressurized lime product (calcium hydroxide 95% by weight) is added as a neutralizing agent to modified potassium sulfate containing 2.8% by weight of unreacted sulfuric acid powder. Next, a thunderstorm with a 20 cm diameter pestle (

500 g of the above-mentioned crushed product is put into an agitator and ground for 30 minutes to obtain a sample.

Using a plate-shaped granulator with a diameter of 45 cm, a rotation speed of 25 rpm, and an angle of 45 degrees, the granules were granulated while spraying water with a sprayer, followed by obtaining a dry product for 4 hours in an electric dryer set at 110 ° C.

Measured properties of granulated water and incoming goods are as follows.

Assembly Moisture: 9.0% by weight

Product hardness: 4.3kg

Granular differentiation rate: 4.1% by weight

<Measurement Method>: (Same as below)

Hardness: Based on the wooden hardness tester. Average of measurements for 20 particles of 6 to 7 meshes.

Differentiation rate: According to the method of combination granular compound fertilizer research meeting. Measured for particles of particle size 6-9 mesh.

Comparative Example 1

Denatured potassium sulfate containing 2.8% by weight of unreacted sulfuric acid powder was pulverized in a pestle to make 10 mesipace, and then pulverized in the same manner as in Example 1, and then added with an equivalent amount of hydrated lime powder and shaken well in a bag. do.

In the same manner as in Example 1, granulation and drying of the use are carried out to obtain a product.

The measurements are as follows.

Assembly Moisture: 13.6 wt%

Product hardness: 0.8kg

Granular differentiation rate: 65.8% by weight

Example 2

The sample was assembled and dried in the same manner as in Example 1, except that the sample obtained by grinding the product obtained in Example 1 was used.

The measurements are as follows.

Assembly Moisture: 8.2% by weight

Product hardness: 5.4kg

Granular differentiation rate: 3.3% by weight

Comparative Example 2

The sample was completely assembled and dried in the same manner as in Example 1, except that the sample obtained by grinding the product obtained in Comparative Example 1 was used.

The measurements are as follows.

Assembly Moisture: 10.6% by weight

Product hardness: 2.8kg

Granular differentiation rate: 8.1% by weight

Example 3

Pressurized granules are added to modified potassium sulphate containing 2.7% by weight of unreacted sulfuric acid as a neutralizing agent, and the pressed granulated product is pulverized with an impact mill to obtain raw materials.

The granules are continuously assembled using a device in which a dryer and a sieve are attached to a dish granulator having a diameter of 3.6 m, a rotational speed of 10 rpm, and an angle of 50 degrees, thereby producing particles from 5 to 9.

Breakdown of supply amount to granulator,

Raw material 3.0 ton / hour

6.0 tons / hour

In addition, the breakdown of the amount of weight is as follows.

Oversize 0.6 ton / hour

3.0 tons / hour

Under size 5.4 tons / hour (circle as it is)

Measured properties of granulated water and product are as follows.

Assembly Moisture: 5.4% by weight

Hardness (6 ~ 7Me): 5.9kg

Product differentiation rate: 4.7% by weight

Comparative Example 3

Denatured potassium sulfate containing 2.7% by weight of unreacted sulfuric acid was ground by an impact mill, and granulated continuously in the same manner as in Example 2 except that a raw material to which hydrated lime was added as a neutralizing agent was used.

Breakdown of supply amount to granulator,

2.5 tons of raw material

Circulated goods 8.5 tons / hour

In addition, the breakdown of the amount of weight is as follows.

Oversize 0.6 ton / hour

2.5 tons / hour

Undersize 7.9 tons / hour (circle as it is)

Measured properties of granulated water and product are as follows.

Assembly Moisture: 5.8% by weight

Product hardness: 2.3kg

Product differentiation rate: 9.2% by weight

Example 4

Denatured potassium sulfate containing 2.8% by weight of unreacted sulfuric acid powder was pulverized in a pestle to make 10 mesh (dier-) paste, and then, 500 g of a pesticide with a 20 cm diameter pestle was pulverized and crushed for 30 minutes. Powder of hydrated lime (95% by weight of calcium hydroxide) is added and shaken in a bag to mix (sample A).

The sample was placed in a 2 liter kneader and sprayed with a sprayer while stirring, and stirred for 10 minutes in total, followed by drying for 4 hours in an electrothermal dryer set at 110 ° C. to obtain a neutralized product.

However, the addition amount by spraying is 7 weight% with respect to a sample.

The neutralized product obtained in the above was ground in a brain injury for 15 minutes to give a powder form (sample B).

Next, using a dish granulator with a diameter of 45 cm, a rotation speed of 25 rpm, and an angle of 45 degrees, Sample B was added, water was sprayed with a sprayer, and then dried in an electrothermal dryer set at 110 ° C. for 4 hours. The physical properties of the obtained incoming goods are as follows.

Product hardness: 2.5kg

Granular Differentiation Rate: 8.3% by weight

(Reference) Assembly moisture: 10.3% by weight

[Comparative Example 4]

A merchandise is obtained in the same manner as in Example 4 except that neutralization is not performed.

The physical properties of incoming goods are as follows.

Hardness of goods: 0.8kg

Granular differentiation rate: 65.8% by weight

(Reference) Assembly moisture: 13.6% by weight

Example 5

A granulated product was obtained in the same manner as in Example 4 except that the sample A 150g and the sample B 350g mixed sample of Example 4 were used.

The physical properties of incoming goods are as follows.

Hardness of goods: 2.1kg

Granular Differentiation Rate: 9.8% by weight

(Reference) Assembly moisture: 11.1% by weight

[Comparative Example 5]

A granulated product was obtained in the same manner as in Example 4 except that 350 g of Sample A and 150 g of Sample B of Example 4 were used.

The physical properties of incoming goods are as follows.

Hardness of goods: 1.2kg

Granular differentiation rate: 49.3 wt%

(Reference) Assembly moisture: 11.2% by weight

Comparative Example 6

A granulated product was obtained in the same manner as in Comparative Example 5 except that magnesium hydroxide (67% by weight of MgO) was used as the neutralizing agent.

The physical properties of incoming goods are as follows.

Hardness of goods: 1.0kg

Granular differentiation rate: 13.8% by weight

(Reference) Assembled moisture: 12.3 wt%

Comparative Example 7

A granulated product was obtained in the same manner as in Example 4 except that magnesium hydroxide was used as the neutralizing agent.

The physical properties of incoming goods are as follows.

Hardness of goods: 2.0kg

Granular differentiation rate: 13.1% by weight

(Reference) Assembly moisture: 10.4% by weight

Example 6

Denatured potassium sulfate containing 2.8% by weight of unreacted sulfuric acid powder was pulverized in a pestle to make it less than 10 mesh (Direr-), and then 500 g of sea urchins having a diameter of 20 cm were added and ground for 30 minutes. do.

Using a plate-type granulator with a diameter of 45 cm, a rotation speed of 25 rpm, and an angle of 45 degrees, the ammonia water was assembled by spraying with a nebulizer, followed by drying in an electric heat dryer set at 110 ° C. for 4 hours to obtain a product. The amount of ammonia added was 0.96 times equivalent to that of unreacted sulfuric acid.

The physical properties of incoming goods are as follows.

Hardness of goods: 2.1kg

Granular Differentiation Rate: 6.8% by weight

(Reference) Assembly moisture: 10.1% by weight

Comparative Example 8

Using the same crushed product of modified potassium sulfate as in Example 6, slaked lime (purity of 95% by weight calcium hydroxide) or magnesium hydroxide (67% by weight of magnesium hydroxide) was added thereto as a neutralizing agent, followed by mixing. It was supplied to, and granulated while spraying water with an atomizer.

The physical properties of the dry goods as in Example 6 are as follows.

Example 7

The granulated product and dried product were obtained in the same manner as in Comparative Example 8 except that the sample obtained by grinding the product obtained in Example 6 was used (neutralizing agent was not added).

The physical properties of incoming goods are as follows.

Hardness of goods: 2.8kg

Granular differentiation rate: 4.4% by weight

(Reference) Assembly moisture: 8.9 wt%

Comparative Example 9

The granular product obtained in Example 6 was granulated and dried in the same manner as in Comparative Example 8 except that a pulverized sample was used (no neutralizing agent was added).

The physical properties of incoming goods are as follows.

Claims (17)

0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, carbonate to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. Granulated potassium sulfate formed by wet granulation with magnesium or ammonia added. 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, carbonate to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. A granulation method of granular potassium sulfate, comprising wet or granulating with magnesium or ammonia. 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide or carbonate to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. Granular potassium sulfate formed by compression molding by addition of at least one powdered neutralizing agent selected from magnesium and wet granulation of the powder obtained by pulverizing the molded article. 0.5 to 2 equivalents of calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide or magnesium carbonate to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. A method of producing granular potassium sulfate, characterized by compression molding by adding at least one powdered neutralizing agent selected from the group, and pulverizing the molded article, followed by wet granulation. The method of claim 4 wherein compression molding is carried out in a roll-press, solidifier, extruder or granulator. The method of claim 4 wherein the wet assembly is carried out with a dish granulator, a drum granulator or an extruder. The method according to claim 4, wherein water, aqueous potassium sulfate solution or potassium sulfate slurry is added so that the granulated water (moisture in the undried wet assembly) at the time of wet granulation is 2 to 20% by weight. 5. The method according to claim 4, wherein the wet granulated product is classified after drying to obtain granular potassium sulfate, and the oversized product is pulverized, but the undersized product is not pulverized or pulverized, and then circulated in the wet granulator. To the modified potassium sulfate containing unreacted sulfuric acid powder obtained by the dry reaction of potassium chloride and sulfuric acid, at least one neutralizing agent selected from 0.5 to 2 times the equivalent of calcium hydroxide, calcium oxide or calcium carbonate is added to the unreacted sulfuric acid powder. Granular potassium sulfate formed by wet-neutralization, drying and grinding a neutralized product, and then wet granulation. At least one neutralizing agent and water selected from 0.5 to 2 times equivalents of calcium hydroxide, calcium oxide or calcium carbonate to modified potassium sulfate containing unreacted sulfuric acid, obtained by dry reaction of potassium chloride and sulfuric acid. Method for producing granular potassium sulfate, characterized in that the wet-neutralization by adding a wet and then dried and pulverized the neutralized product. The method according to claim 10, wherein the amount of water added during wet neutralization is 2 to 20% by weight based on the modified potassium sulfate. The method according to claim 10, wherein the neutralized dry pulverized product and the wet neutralized product are mixed in a weight ratio of the neutralized dry pulverized product 2: 1 or more. A granular potassium sulfate formed by wet granulation by adding 0.5 to 1.2 times the equivalent of ammonia to unreacted sulfuric acid to modified potassium sulfate containing unreacted sulfuric acid powder obtained by dry reaction of potassium chloride and sulfuric acid. Preparation of granular potassium sulfate, wet granulation is performed by adding 0.5 to 1.2 times the equivalent of ammonia to unreacted sulfuric acid to modified potassium sulfate containing unreacted sulfuric acid, which is obtained by dry reaction of potassium chloride and sulfuric acid. Way. 15. The method according to claim 14, wherein water or ammonia water is used as coarse water in wet assembly. 15. The method of claim 14, wherein the wet assembly is performed with a dish dryer, drum granulator or extruder. 15. The method according to claim 14, wherein the wet granulated product is classified into sieves after drying to obtain granular potassium sulfate, and the oversized product is pulverized, but the undersize product is circulated in the wet granulator without crushing or pulverizing.

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