JPS6335485A - Granular potassium sulfate and manufacture - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Technology] The present invention relates to well-shaped granular potassium sulfate and a method for producing the same. More specifically, the present invention involves wet neutralization by adding a predetermined amount of a neutralizing agent such as calcium hydroxide to modified potassium sulfate containing unreacted sulfuric acid, drying and pulverizing the neutralized amount, and then wet neutralizing the modified potassium sulfate containing unreacted sulfuric acid. This invention relates to granular potassium sulfate obtained by granulation and a method for producing the same.

[Conventional technology]

Generally, granulation of fertilizers in recent years has been carried out for the purpose of improving fertilization workability and adapting to mechanical fertilization.

In particular, mechanical fertilization has recently become widespread, and there is a strong demand for spherical potassium sulfate with good fluidity. In addition, granulated single fertilizers are used in bulk blend fertilizers, which have recently become popular. Currently, various types of fertilizers are granulated using methods suited to their physical properties and provided to the market. Granular products are also required for potassium sulfate as a raw material for potassium fertilizer. However, regarding the granulation of potassium sulfate, there are various manufacturing and quality problems as described below. Since the potash sulfate has poor granulation properties, it is difficult to efficiently obtain granular products with a desired particle size range.

When granular potassium sulfate obtained by compressing and granulating a potassium sulfate-water mixture using a roll press or the like is used as the raw material for the bulk blend fertilizer described above, granular sulfuric acid is produced during handling and transportation of the resulting bulk blend fertilizer. As a result of the pulverization of the potash portion, classification of the bulk blend fertilizer occurs, and segregation of fertilizing components by particle size becomes a problem.

Incidentally, 6 to 12 mesh granular potassium sulfate is generally used as a raw material for compound fertilizers or bulk blend fertilizers. In such applications, the granular potassium sulfate obtained by the above-mentioned compression granulation method has undergone a process of compression, disintegration, and sieving, so its surface has many protrusions and its compression hardness is relatively high. The crushing surfaces are subject to abrasion, and during flowing handling and transportation of the granulated product, pulverization of the individual particles from the fragile side occurs. Potassium sulfate, which is compressed and granulated using a roll press using the conventional method, is used as a raw material for bulk blend fertilizers, but the pulverization rate of this product is approximately! 0%
This is significantly higher than the average pulverization rate of 2 to 3% for other granular fertilizers.For this reason, granular potassium sulfate is recycled before bulk blending, so it is not necessary to process it. Granular products are requested.

[Purpose of the invention]

As a result of various studies to obtain the desired potassium sulfate, the present inventors wet-neutralized the modified potassium sulfate containing unreacted sulfuric acid by adding a predetermined amount of a neutralizing agent such as calcium hydroxide. The present invention (
Two inventions) were completed.

As is clear from the above description, an object of the present invention is to provide a method for granulating potassium sulfate that has a significantly lower pulverization rate and good fluidity, and granular potassium sulfate obtained by the method.

[Structure and effects of the invention]

The present invention (second invention) has the following main configurations (1) and (2) and embodiment configurations (3) and (4).

(1) Modified potassium sulfate containing unreacted sulfuric acid obtained by dryly reacting potassium chloride and sulfuric acid with calcium hydroxide, calcium oxide, or Granular potassium sulfate obtained by performing wet neutralization by adding one or more neutralizing agents selected from calcium carbonate, drying the neutralized amount, pulverizing the dried product, and then wet granulating it.

(2) To the modified potassium sulfate containing unreacted sulfuric acid obtained by dry reaction of potassium chloride and sulfuric acid, calcium hydroxide of 0.5 to 2 times the unreacted sulfuric acid, 3 H, 1, Granular sulfuric acid, which is characterized by wet neutralization by adding one or more neutralizing agents selected from calcium oxide or calcium carbonate, drying the neutralized amount, pulverizing the dry product, and then wet granulation. Method of producing potash.

(3) The method according to item (2) above, wherein in the wet neutralization, the amount of water added is 2 to 20 weight percent based on the modified potassium sulfate.

(4) A mixture of the neutralized dry pulverized product and the wet neutralized product in a weight ratio of 2:1 or more is granulated.
).

As the 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 manufacturing methods can of course also be used.

There are no limitations on the degree of powderiness or particle size of the raw material potassium sulfate, and it can be used in the present invention as long as it can be sufficiently wet neutralized. In other words, it is preferable that the powder be in the form of a 20-mesh (Tyler) pass, and coarse particles such as 5 mesh are undesirable.If coarse particles such as 5 mesh are used, wet neutralization may be incomplete. Therefore, the effect of the present invention is reduced. That is, there is a tendency that the granulation property of the wet neutralized product deteriorates, the yield of granules decreases, and the hardness (compression fracture pressure) of the obtained granules also decreases.

As the neutralizing agent used in the present invention, a powdered calcium compound can be used. Specifically, one or more compounds selected from calcium compounds such as calcium hydroxide, calcium oxide, or calcium carbonate are preferably used.

The amount used is 0.5 to 2.0 times equivalent to the unreacted sulfuric acid content in the modified potassium sulfate determined in advance, preferably 0.8
~1.5 times equivalent. If the amount is less than 0.5 times equivalent, the acidity of the potassium sulfate after neutralization will be extremely high (low pH), making it unsuitable as a fertilizer, and if it exceeds 2 times equivalent, the fertilizing component (K2O While the species density of
This is not desirable because it does not particularly improve granulation properties.

The amount of water used for wet neutralization in the method of the present invention is not limited, as long as it allows neutralization to proceed sufficiently.0 Usually, it is 2 to 20% by weight based on the modified potassium sulfate (wet amount basis, the same applies hereinafter). ), preferably 4 to 15ii percent. If the amount is less than 2% by weight, neutralization will not proceed sufficiently and the effect of the present invention will be reduced. Moreover, if it exceeds 20% by weight, the energy required for drying becomes large, which is uneconomical.

The method of mixing the above modified potassium sulfate, neutralizing agent, and water is not limited. For example, the above three mixed raw materials may be charged simultaneously or sequentially into an open or closed mixer.
Mixing is carried out at too much °C, preferably 20-80 °C, for 1 minute to 1 hour, preferably 5 minutes to 30 minutes. However, as long as the effects of the present invention are not impaired, it is also possible to advance neutralization by mixing only the modified potassium sulfate and the neutralizing agent in advance and feeding the mixture together with water to a wet granulator. The feeding ratio of several bottles is within a range of 0.5 or less times by weight to the neutralized potassium sulfate fed to the wet granulator. By doing so, it is possible to partially omit the drying process for the amount of neutralization among the two drying processes in the entire process from raw materials to products.

The above-mentioned mixer is not limited as long as it is a rotating part that can mix powder-like materials in a short time, and for example, a tank-type blender with an agitator, a ribbon printer, etc. can be used.

Further, the above-mentioned wet granulation is usually carried out using a transfer granulator such as a dish-type granulator or a drum-type granulator, or an extruder, but is not limited thereto.

The amount of water supplied to the granulator is within the above upper limit (0,
5) There is no limitation as long as it is the following.

However, as mentioned above, the amount of wood used for wet neutralization is typically 2 to 20 weight percent to 4 to 15 weight percent.

Furthermore, although the type of dryer and drying method used in the present invention are not limited, it is desirable to select mild conditions in order to reduce powdering during drying of the wet granulated product (9) without impairing the effects of the present invention. As far as possible, the same dryer may be used for drying the wet-neutralized product and the wet-granulated product.Prior to this drying, the above-mentioned granulation conditions are selected so that the wet-granulated product can be sufficiently neutralized. Should. This is because, in the method of the present invention, the neutralization reaction does not necessarily proceed to the necessary and sufficient extent only by the initial wet neutralization of the modified potassium sulfate, and the wet-neutralized product is wet-processed through subsequent pulverization. This is because neutralization often does not proceed sufficiently until the grains are received.

The dried potassium sulfate is classified using a sieve machine and divided into oversize products, finished products, and undersize products.

Oversized products are pulverized and undersized products are recycled to the wet granulator without being pulverized or after being pulverized. When the same dryer is used for both dryer use steps, the wet neutralized and dried product is present in the undersize amount described above. The progress of neutralization of Ohe-sized products is usually sufficient, and by pulverizing and feeding this to a wet granulator, it is possible to replace the wet-neutralized dry product by pulverizing and feeding it to a wet granulator. Can be done.

The above steps will be explained with reference to the attached drawings.

In the figure, modified potassium sulfate and neutralizing agent supplied from pipes 1 and 2 are supplied to mixer A via pipe 3.

Inside the mixer, water is sprayed from pipe 4, the three raw materials are mixed, and a neutralization reaction proceeds. The neutralized mixture is sent via piping 5 to dryer B (also used as a dryer) together with the wet granulated product sent via piping 15, and the potassium sulfate dried in B is sent to packet elevator-6.
The particles are sent to sieve C via C, where they are sieved in the order of particle size into oversize products, products, and undersize products.

The oversized product is sent to a crusher via piping 7 and crushed.

The product is taken out from the pipe 9.

The undersized product is sent via pipe 11 to the grinder mE where it is ground, or it is sent as is (without being ground) through pipe 1O.

Potassium sulfate other than these products (note: over- or under-sized products after pulverization, and under-sized products that have not been pulverized) is circulated to the wet granulator F via the flow conveyor 13 and piping 13'.

In F, water of about 50% by weight or less is sprayed onto the potassium sulfate from the pipe 14 to perform granulation.

The undried granular potassium sulfate wet-granulated as described above is
As mentioned above, the neutralized potassium sulfate from the mixer A is sent to the dryer B through the pipe 15 (note: wet neutralized product).
dried at the same time.

The first effect of the present invention is that the shape of the obtained granular product is good (
It is spherical) and has good fluidity. The granular products obtained according to the invention are therefore well suited for mechanical fertilization.

The second effect of the present invention is that the pulverization rate of the granular product obtained is relatively low. According to the measurement method 10
% by weight, and the powdering rate is lower than that of conventional compression granulated products (pulverizing rate of about 10%).

In addition, the powdering rate (Mg(O
Considering that H) (in cases other than using 2 as a neutralizing agent) is several tens of percent, it can be said that the method of the present invention, which does not require compression granulation, and the effects of the present invention are remarkable.

The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 Modified potassium sulfate containing 2.8% by weight of unreacted sulfuric acid was crushed in a mortar to form a lO mesh (Tyler) pass, and then 500g of it was placed in a leprosy machine having a mortar with a diameter of 20cm. Add an equivalent amount of slaked lime (calcium hydroxide purity 95% by weight) and grind for 30 minutes.
Powder was added and shaken well in a bag to prepare a sample (referred to as sample A).

The sample was placed in a 2 liter Nigu and sprinkled with water using a sprayer while stirring. After stirring for a total of 10 minutes, the temperature was increased to 110°C.
A neutralized product was obtained by drying for 4 hours in an electric heating dryer set at .

The amount of water added by this sprinkling was 7% by weight based on the sample.

The neutralized product obtained above was pulverized for 15 minutes using a disintegrator to form a powder (referred to as sample B).

Next, the diameter of the plate is 45 cm, and the rotation speed is 25 rpm.
Using a dish-type granulator with an angle of 45 degrees, Sample B was charged and water was sprayed with a sprayer, followed by drying for 4 hours in an electric heating dryer set at 110°C. The physical properties of the obtained granular product were as follows.

Granular product hardness: 2.5 kg 〃 Powdering rate: 28.3% by weight (reference) Granulation moisture: 10.3 tt [Measurement method] ■Hardness: 6-7 mesh (Tyler) size granules 20 by Honya type hardness tester Comparative Example-1 Measurement of granules with a particle size of 6 to 9 mesh according to the method of Combination Granular Compounded Fertilizer Study Group - Average value of the measured values for each particle Comparative Example-1 Granular products were prepared in the same manner as in Example 1 except that neutralization was not performed. The physical properties of the obtained granular product were as follows.

Hardness of granular product: 0.8kg I! Powdering rate: 65.8% by weight (reference) Granulation moisture: 13.8% by weight Example-2 The same procedure as Example-1 was used except that a mixed sample of 50 g of sample A of Example-1 and 8350 g of sample was used. A granulated product was obtained.

The physical properties of the granular product were as follows.

Hardness of granular product: 2.1 kg 1/ Powdering rate: 9.8% by weight (reference) Granulation moisture: 11.1 // Comparative example-2 A mixed sample of 350 g of sample A of Example-1 and 8150 g of sample A granulated product was obtained in the same manner as in Example-1 except for the use.

The physical properties of the granular product were as follows.

Hardness of granular product: 1.2 kg 1/ Powdering rate: 49.3 weight percent (reference)
Granulation moisture content: 11.2/1 Comparative Example-3 A granulated product was obtained in the same manner as Comparative Example-2 except that magnesium hydroxide (Mg087% by weight) was used as a neutralizing agent.

The physical properties of the granular product were as follows.

Hardness of granular product: 1.0 kg 1/ Powdering rate: 13.8 weight percent (reference) Granulation moisture: 12.3 tt Comparative example-4 Example-4 except that magnesium hydroxide was used as a neutralizing agent
A granulated product was obtained in the same manner as in 1.

The physical properties of the granular product were as follows.

Hardness of granular product: 2.0 kg 1/ Powdering rate: 13.1 weight percent (reference) Granulation moisture: 10.4 tt

[Brief explanation of the drawing]

The figure is a flow sheet of the apparatus used in the method of the invention. that's all

Claims (4)

[Claims] (1) Modified potassium sulfate containing unreacted sulfuric acid obtained by dry reaction of potassium chloride and sulfuric acid is added with calcium hydroxide, calcium oxide or carbonic acid in an amount of 0.5 to 2 times equivalent to the unreacted sulfuric acid. Granular potassium sulfate obtained by wet-neutralizing by adding one or more neutralizing agents selected from calcium, drying the neutralized product, crushing the dry product, and then wet-granulating it. (2) Modified potassium sulfate containing unreacted sulfuric acid obtained by dryly reacting potassium chloride and sulfuric acid with calcium hydroxide, calcium oxide, or carbonic acid in an amount of 0.5 to 2 times the amount of unreacted sulfuric acid. A method for producing granular potassium sulfate, which comprises performing wet neutralization by adding one or more neutralizing agents selected from calcium, drying the neutralized product, pulverizing the dry product, and then performing wet granulation. (3) The method according to claim (2), wherein in the wet neutralization, the amount of water added is 2 to 20 percent by weight based on the modified potassium sulfate. (4) The method according to claim (2), which comprises granulating a mixture of a neutralized dry pulverized product and a wet neutralized product in a weight ratio of 2:1 or more.