JPH0229609B2 - RYUJORYUANNOSEIZOHOHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing granular ammonium sulfate by dissolving ammonium sulfate, which is not suitable for bulk blending, such as powdered ammonium sulfate, in water and recrystallizing it. The supply and demand of ammonium sulfate in Japan is due to overproduction, and the surplus in domestic demand is dependent on exports. However, granular ammonium sulfate for bulk blending, which is used for fertilizing by arbitrarily and quickly combining granular phosphorus and potassium components in their bulk form, is produced in small quantities and is always in short supply. . The above granular ammonium sulfate for bulk blending may be dice-shaped, spherical, or
Rice grain-like products are requested. Even if granular ammonium sulfate is not produced by producing ammonium sulfate mother liquor from a mother liquor containing free sulfuric acid and ammonia in a saturator and introducing this into a crystallization tank and concentrating it, the ammonium sulfate crystals obtained are columnar or plate-shaped. Therefore, it was not possible to produce granular ammonium sulfate in the shape of dice, spheres, or rice grains. As a countermeasure for this problem, a method is proposed in which nitric acid or ammonium nitrate is added as a modifier to the ammonium sulfate mother liquor in the process of producing granular ammonium sulfate through a crystallizer to crystallize the ammonium sulfate mother liquor in an amount of 1 to 10% (in terms of ammonium nitrate). 56-109814), a method in which sulfamic acid or ammonium sulfamate is added as a modifier to ammonium sulfate mother liquor in an amount of 0.5 to 5% in terms of sulfamic acid (Japanese Patent Application Laid-Open No. 56-109815), or a method in which a modifier is added to ammonium sulfate mother liquor. A method of crystallizing by adding nitric acid or ammonium nitrate in the form of ammonium nitrate in an amount of 1 to 10% and sulfamic acid or ammonium sulfamate in the form of ammonium sulfamate in the range of 0.5 to 5% as agents (JP-A-109816-1987).
Proposals such as
The yield for bulk blending is not necessarily satisfactory. This invention was made in view of the above circumstances,
Ammonium sulfate, which is not suitable for bulk blending, is dissolved in water to form an ammonium sulfate mother liquor, and in the ammonium sulfate mother liquor, sulfamic acid or its salt is added as a modifier, and hydrosulfite, etc., which exhibits a modulating effect through reduction action, or the like. Adding one or more types of cyclic or chain condensed phosphoric acid or its salts, ethylenediaminetetraacetic acids, oxalic acid, etc., which exhibit a mode crystal effect through chelating action,
This is a method for producing granular ammonium sulfate, which is characterized by crystallizing it again. Examples of modifiers that exhibit a modulating effect through reduction include hydrosulfite, sodium hydrosulfide, ascorbic acid, formic acid, and the like. In addition, examples of modifiers that exhibit a modulation effect through chelating action include cyclic or chain condensed phosphoric acids or salts thereof, ethylenediaminetetraacetic acids, oxalic acid, and nitrilotriacetic acid. Further, since the amount of sulfamic acid or its salt added depends on the synergistic effect with the crystal modifier used in combination, a sufficient effect can usually be obtained with an amount of 0.5% or less based on the ammonium sulfate mother liquor. In the following examples, crystallization was carried out by cooling, but the same effect can be obtained even if crystallization is carried out by concentration. Furthermore, since the ammonium sulfate crystals were crystallized while being mechanically stirred, they had a spherical shape, but when no mechanical stirring was performed, such as in the Oslo type, the ammonium sulfate crystals produced were dice-shaped, but they are grains suitable for bulk blending. We have confirmed that the diameter is maintained. Example The drawing shows the test equipment used and shows the internal volume.
Put 50% water and about 30kg of ammonium sulfate crystals with a particle size of 20 mesh or less into the mother liquor tank 1 of 75, stir thoroughly while heating to around 40℃ with heater 2 to bring it to a saturated state, as shown in Table 1. After adjusting the sulfuric acid concentration and crystal modifier concentration, the saturated mother liquor was introduced into the crystallization tank 5 with an internal volume of 15 at a rate of about 2.1/min via the cooling tank 4 using the pump 3.
The overflow was again circulated to the mother liquor tank 1, and when the temperature difference between the mother liquor tank 1 and the crystallization tank 5 reached 5°C, 300 g of seed crystals of 20 meshes (0.84 mm) or less were added. After that, the temperature of mother liquor tank 1 is reduced to 35℃ while gradually cooling.
±1℃, the temperature of crystallization tank 5 is 30℃±1℃ and 5~6℃
While maintaining a temperature difference of
Thereafter, extraction was performed every hour. During this time, the stirrer 7 of the crystallization tank 5 was stirred at 300 rpm except during extraction. The amount taken out was adjusted so that the slurry zone at the bottom of the crystallization tank 5 maintained approximately 1.8 (approximately 1.6 kg of crystals) when the stirrer was in a rest state with 7 rotations. Note that 8 represents a stirrer and 9 represents cooling water. The properties of the ammonium sulfate obtained at this time are shown in Table 1. Note that the shape factor (a/b) in Table 1 is obtained by randomly measuring ammonium sulfate crystals using a scale magnifying glass, and indicates the crystal growth axis as a and the axis perpendicular to a as b. Moreover, the crystal shape shows the result of visual observation.

【table】

[Table] As shown in Table 1, sulfamic acid or ammonium sulfamate as a modifier and sodium hydrosulfite which exhibits a modulating effect through reduction action, or sodium hydrosulfite which exhibits a modulating effect through chelating action. In the case of the method of the present invention in which sodium metaphosphate, sodium hexametaphosphate, ethylenediaminetetraacetic acid, and oxalic acid were added, the shape factor was greatly improved and the crystal shape became spherical compared to the comparative example in which these were added alone. With becoming,
Particle size 12~ required for bulk blending
The yield of 8-mesh significantly increased and it could be sold as granular ammonium sulfate for bulk blending. The reason for this is not clear, but there is a synergistic effect between the addition of sulfamic acid, which is thought to form a double salt with ammonium sulfate and exhibit a modulating effect, and the modulating agent, which exhibits a modulating effect through reduction or chelating action. This is thought to be due to the effect of increasing the mode crystal effect. Furthermore, the ammonia nitrogen content in ammonium sulfate is 21.1% or more, and although the sulfamic acid content is not listed, it is 0.1% or less, which fully satisfies the fertilizer standards. It was hot. As described above, with the present invention, granular ammonium sulfate, which could not be conventionally used as granular ammonium sulfate for bulk blending and was granulated with phosphorus and potassium components as a chemical fertilizer, can be made into granular ammonium sulfate for bulk blending in a high yield. The benefits to the fertilizer industry are significant, as it enables rapid formulation and eliminates the need for a granulation process.

[Brief explanation of drawings]

The drawing is an explanatory diagram of a test device used in Examples. 1...Mother liquid tank, 2...Heater, 3...Pump, 4...Cooling tank, 5...Crystallization tank, 6...Slurry extraction pipe, 7, 8...Stirrer.

Claims (1)

[Claims] 1. Ammonium sulfate, which is not suitable for bulk blending, is dissolved in water to form an ammonium sulfate mother liquor, and in the ammonium sulfate mother liquor, sulfamic acid or its salt is added as a modulating agent, and hydrosulfite, etc., which exhibits a modulating effect by reduction, is added to the ammonium sulfate mother liquor.
Alternatively, production of granular ammonium sulfate characterized by adding and crystallizing one or more of cyclic or chain condensed phosphoric acids or their salts, ethylenediaminetetraacetic acids, oxalic acid, etc., which exhibit a mode crystal effect through chelating action. Method.