JP4625586B2 - Magnesium hydroxide granular material and granular fertilizer containing magnesium hydroxide - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnesium hydroxide granular material suitable for use as a fertilizer.
[0002]
[Prior art]
Magnesium is one of the five major nutrients of plants and is the main component of chlorophyll, and at the same time plays an important role in promoting phosphate absorption and movement within the plant. When a plant is deficient in magnesium, the leaves become yellow, fallen leaves, and even die. Magnesium-containing fertilizers such as bitter fertilizer (magnesium oxide), hydroxylated bitter fertilizer (magnesium hydroxide), and sulfated bitter fertilizer (magnesium sulfate) for the purpose of preventing the harmful effects of magnesium deficiency in plants. Is being used. Among magnesium-containing fertilizers, hydroxylated mashed fertilizers are alkaline, and are particularly effective in acidic soils, and are unlikely to condense by reacting with atmospheric moisture during storage, such as magnesium oxide. It is particularly useful because it has advantages.
[0003]
Magnesium-containing fertilizers have conventionally been applied alone, but recently, use as a component of bulk blended fertilizers has also been studied. It is desirable for the bulk blend compound fertilizer to show homogeneity throughout the fertilizer so that the fertilizer composition does not change depending on the fertilization position. Therefore, the granular fertilizer used for the bulk blended fertilizer is preferably high in hardness so as not to easily disintegrate due to mechanical impact.
[0004]
As a magnesium hydroxide granule for fertilizer having high hardness, JP-A-11-343187 proposes a magnesium hydroxide granule obtained by mixing and granulating magnesium hydroxide powder and a binder (magnesium sulfate aqueous solution). Yes. In the examples of this publication, granular magnesium hydroxide having a hardness of 3 to 6 kg is obtained.
[0005]
[Problems to be solved by the invention]
The magnesium hydroxide granular material having high hardness is not easily broken even when subjected to mechanical impact. However, according to the inventor's study, magnesium hydroxide granules and magnesium hydroxide granules (or other granular fertilizers) can be used during transportation and fertilization even if the magnesium hydroxide granules have high hardness. It has been clarified that the surface of the magnesium hydroxide granular material may be scraped to produce powdered magnesium hydroxide.
[0006]
As a method of making the surface of the magnesium hydroxide granular material difficult to be scraped (that is, increasing the strength of the surface), it is effective to increase the amount of binder added when producing the granulated material from the magnesium hydroxide powder. . However, according to the study of the present inventor, if the amount of binder added is excessively large, it tends to be difficult to produce a granulated product from magnesium hydroxide powder, which is a problem in ordinary industrial granulating equipment. It has been found that it is difficult to increase the strength of the surface of the magnesium hydroxide granular material until the surface becomes difficult to be scraped with a binder addition amount that does not become so.
[0007]
Accordingly, an object of the present invention is to provide a magnesium hydroxide granular material that can be easily produced industrially and is difficult to produce magnesium hydroxide powder during transportation and fertilization. Another object of the present invention is to provide a method for producing a magnesium hydroxide granular material in which magnesium hydroxide powder is less likely to be produced during transportation and fertilization. Another object of the present invention is to provide a fertilizer containing magnesium hydroxide granular material that is difficult to produce magnesium hydroxide powder as an active ingredient.
[0008]
[Means for Solving the Problems]
In the present invention, granular magnesium hydroxide having an average particle diameter in the range of 1 to 5 mm is used as a core, and two or more coating layers made of a reaction product of sulfuric acid and magnesium hydroxide particles are formed around the magnesium hydroxide. It is in the magnesium hydroxide granular material characterized by this.
[0009]
The magnesium hydroxide granular material of the present invention has two or more strong coating layers formed on the surface thereof, so that it is difficult to produce magnesium hydroxide powder. In other words, the powdering rate measured by the following method Becomes lower. The preferable powdering rate in the magnesium hydroxide granular material of the present invention is 10% or less.
[0010]
(1) Three cylindrical magnetic pots (inner diameter: 100 mm × depth: 100 mm) with 100 g of magnesium hydroxide particles and magnetic balls with a diameter of about 30 mm and a weight of about 35 g are added so that the total weight is about 105 g. And cover.
(2) Rotate the cylindrical magnetic pot for 15 minutes at a speed of 75 revolutions per minute at the axial position in a state where the cylindrical magnetic pot is tilted sideways.
(3) Magnesium hydroxide particulates are taken out from the magnetic pot, and a powder of 16 mesh or less is collected with a standard sieve, its weight (A) is obtained, and the powdering rate is obtained by the following formula (1).
[0011]
Powdering rate (%) = A (g) / 100 (g) × 100 (1)
[0012]
The present invention also includes 20 to 60 parts by mass of granular magnesium hydroxide having an average particle size in the range of 1 to 5 mm, 5 to 30 masses of magnesium hydroxide powder having a water content of less than 2% by mass and an average particle size of less than 1 mm. 1 part by weight, 5 to 30 parts by weight of magnesium hydroxide cake having a moisture content of 2 to 30% by weight, and 1.5 to 4.0 parts by weight of sulfuric acid having a concentration of 3 to 18 mol / liter, respectively, 5-30 parts by mass of magnesium hydroxide powder having a moisture content of less than 2% by mass and an average particle size of less than 1 mm, 5-30 parts by mass of magnesium hydroxide cake having a moisture content of 2-30% by mass, and a concentration of 3-18 mol / There is also a method for producing a magnesium hydroxide granular material, which includes adding 1.5 to 4.0 parts by mass of liter of sulfuric acid, granulating and drying.
[0013]
The present invention also resides in a magnesium hydroxide-containing granular fertilizer (bulk blend compound fertilizer) containing the magnesium hydroxide granular material as an active ingredient.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The magnesium hydroxide granular material of the present invention is characterized in that two or more coating layers made of a reaction product of sulfuric acid and magnesium hydroxide particles are formed around granular magnesium hydroxide. That is, the magnesium hydroxide granular material of the present invention is characterized by being covered with two or more coating layers. In the magnesium hydroxide granular material of the present invention, the coating layer is usually in the range of 2 to 4 layers, preferably 2 layers.
[0015]
The granular magnesium hydroxide as a nucleus in the magnesium hydroxide granular material of the present invention desirably has a spherical shape with an average particle diameter in the range of 1 to 5 mm, preferably in the range of 2 to 3 mm. There is no restriction | limiting in particular in the manufacturing method of granular magnesium hydroxide. For example, magnesium hydroxide powder and a binder (usually sulfuric acid) are put into an agitation granulator such as a Henschel mixer, and the mixture can be agitated and mixed for granulation.
[0016]
In the present invention, the coating layer is made of a reaction product of sulfuric acid and magnesium hydroxide particles. The reaction product of sulfuric acid and magnesium hydroxide particles also includes a reaction product of magnesium sulfate aqueous solution and magnesium hydroxide particles. The coating layer can be formed by stirring and mixing a sulfuric acid source and a magnesium hydroxide particle source together with granular magnesium hydroxide (core) and granulating. For stirring and mixing, a normal stirring granulator such as a Henschel mixer can be used.
[0017]
As the sulfuric acid source of the coating layer, sulfuric acid or a magnesium sulfate aqueous solution can be used. Usually, sulfuric acid having a concentration of 3 to 18 mol / liter (preferably 8 to 13 mol / liter) is used.
[0018]
The addition amount of the sulfuric acid source is preferably an amount such that the sulfuric acid component (sulfuric acid ion amount) contained in the coating layer falls within the range of 6 to 15% by mass. The intensity | strength of a coating layer becomes it low that the quantity of the sulfuric acid component contained in a coating layer is less than 6 mass%. On the other hand, if the amount of the sulfuric acid source added is too large, granulation becomes difficult.
[0019]
As the magnesium hydroxide particle source of the coating layer, a magnesium hydroxide powder having a moisture content of less than 2% by mass, a magnesium hydroxide cake having a moisture content of 2 to 30% by mass, or a combination thereof can be used. Usually, a mixture of magnesium hydroxide powder and magnesium hydroxide cake is used.
[0020]
The magnesium hydroxide powder used as the magnesium hydroxide particle source has an average particle size of 1 mm or less, preferably 100 μm or less. Magnesium hydroxide powder is obtained by pulverizing granular magnesium hydroxide of a size unsuitable for use as a core obtained in the production of the core magnesium hydroxide from the viewpoint of material cost. Is preferably used.
[0021]
There is no particular limitation on the size and shape of the magnesium hydroxide cake used as the magnesium hydroxide particle source. As the magnesium hydroxide cake, a cake obtained by concentrating and dehydrating a magnesium hydroxide slurry obtained by adding lime milk to seawater can be used.
[0022]
The magnesium hydroxide granular material of the present invention can be used as a fertilizer alone or mixed with other granular fertilizers. Examples of other granular fertilizers include ammonium sulfate fertilizer, ammonium nitrate fertilizer, ammonium chloride fertilizer, lime nitrate fertilizer, lime nitrogen fertilizer, phosphate fertilizer, urea fertilizer, slaked lime fertilizer, and calcium carbonate fertilizer.
[0023]
【Example】
[Example 1]
(1) Production of granular magnesium hydroxide (core) 85 parts by mass of magnesium hydroxide powder in the range of 0.1 to 0.5 mm and 15 parts by mass of sulfuric acid having a concentration of 11.5 mol / liter The mixture was put into a mixer, mixed with stirring and granulated to obtain granular magnesium hydroxide (sulfuric acid component amount: 10% by mass). The obtained granular magnesium hydroxide was dried at 120 ° C. to reduce the water content to 1% by weight or less, and sieved to select granular magnesium hydroxide having a particle size of 2 to 3 mm, which was used as a core. The granular magnesium hydroxide having a particle size other than 2 to 3 mm was pulverized with a pulverizer until the particle size became 100 μm or less, and used as a magnesium hydroxide source for the coating layer.
[0024]
(2) 25 parts by mass of granular magnesium hydroxide having a coating particle size of the first coating layer in the range of 2 to 3 mm, magnesium hydroxide powder having a particle size of 100 μm or less (water 1 mass%, sulfuric acid component content 10 mass) %) 10 parts by weight, 15 parts by weight of magnesium hydroxide cake (water content 22% by weight) and 1.88 parts by weight of sulfuric acid having a concentration of 11.5 mol / liter were each put into a Henschel mixer, mixed and stirred for granulation. .
[0025]
(3) Formation of second coating layer Subsequently, 25 parts by mass of magnesium hydroxide powder having a particle size of 100 μm or less (water content 1 mass%, sulfuric acid component content 10 mass%), magnesium hydroxide 25 parts by mass of cake (water content 22% by mass) and 3.12 parts by mass of sulfuric acid having a concentration of 11.5 mol / liter were added, mixed and stirred, and granulated to form a second coating layer. The resulting granulate was then dried at 120 ° C. The granular material after drying had a particle size of 2.8 to 4.0 mm.
[0026]
[Evaluation and results]
(1) The cross section of the magnesium hydroxide granular material produced in Example 1 was observed with a microscope. The micrograph is shown in FIG. As shown in FIG. 1, it can be seen that the magnesium hydroxide granular material produced in Example 1 has two layers of coating layers formed around the granular magnesium hydroxide as a core.
[0027]
(2) When the powdering rate of the magnesium hydroxide granular material manufactured in Example 1 was measured by the above method, it was 7.6%.
[0028]
【The invention's effect】
The magnesium hydroxide granular material of the present invention has a high strength because the surface is covered with two or more coating layers, and powder magnesium hydroxide is hardly generated due to scraping of the surface during transportation or fertilization. Therefore, the magnesium hydroxide containing granular fertilizer (bulk blend compound fertilizer) which contains the magnesium hydroxide granular material of this invention as an active ingredient has high homogeneity.
According to the manufacturing method of the magnesium hydroxide granular material of the present invention, the magnesium hydroxide granular material that hardly generates powdered magnesium hydroxide during transportation and fertilization can be easily industrially manufactured.
[Brief description of the drawings]
1 is a cross-sectional photograph of a magnesium hydroxide granular material produced in Example 1. FIG.

Claims (4)

It is characterized in that two or more coating layers made of a reaction product of sulfuric acid and magnesium hydroxide particles are formed around a granular magnesium hydroxide having an average particle size in the range of 1 to 5 mm. Magnesium hydroxide granules. The magnesium hydroxide granular material according to claim 1, wherein the powdering rate is 10% or less. 20 to 60 parts by mass of granular magnesium hydroxide having an average particle size in the range of 1 to 5 mm, 5 to 30 parts by mass of magnesium hydroxide powder having an average particle size of less than 1 mm and less than 2% by mass, After mixing and granulating 30 to 30 parts by weight of magnesium hydroxide cake and 1.5 to 4.0 parts by weight of sulfuric acid having a concentration of 3 to 18 mol / liter, the water content is less than 2 parts by weight. 5 to 30 parts by mass of magnesium hydroxide powder having an average particle size of less than 1 mm, 5 to 30 parts by mass of magnesium hydroxide cake having a moisture content of 2 to 30% by mass, and 1.5 to 1.5 mol of sulfuric acid having a concentration of 3 to 18 mol / liter The manufacturing method of the magnesium hydroxide granular material of Claim 1 including adding -4.0 mass part, granulating, and drying. Magnesium hydroxide-containing granular fertilizer containing the magnesium hydroxide granular material according to claim 1 or 2 as an active ingredient.

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