JPS6038338B2 - Method for producing granular ammonium sulfate - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing granular ammonium sulfate.

Since ammonium sulfate is hygroscopic, it solidifies when stored for a long period of time, requiring pulverization.In recent years, in order to quickly and arbitrarily produce and blend nitrogen, chloride, and potassium components, several types of granular raw materials have been mixed together, and a bulk material has been developed. Measures are being taken to reduce costs by transporting and fertilizing raw materials.

Under these circumstances, ammonium sulfate crystal grains are required to have a large and round shape.

Conventional production of granular ammonium sulfate involves producing ammonium sulfate from a mother liquor containing free sulfuric acid and ammonia in a saturator, and supplying the mother liquor with a constant degree of saturation, free acid concentration, and temperature to a granulation machine, where water is removed. By evaporating, the mother liquor is concentrated and the degree of supersaturation is increased to generate ammonium sulfate crystals, and the crystals are grown and classified to take out granular ammonium sulfate from the bottom of the granulator, and water and crystals are removed in the granulator. The mother liquor after washing is circulated in a saturator, but the ammonium sulfate crystals produced in this way are all hexagonal prisms, square prisms, or plates, and are inevitably large and rounded. Granular ammonium sulfate could not be produced.

The present invention was made in view of this situation,
In the process of producing granular ammonium sulfate from an ammonium sulfate mother liquor through a crystallizer, nitric acid, sulfamic acid, or its ammonium salt is simultaneously added to the ammonium sulfate mother liquor as a soot crystallizing agent, and nitric acid is 1 to 10%, and sulfamic acid is 1 to 10% in terms of ammonium salt. 0
．． This is a method for producing granular ammonium sulfate in which 5 to 5% of ammonium sulfate is added and crystallized.

Hereinafter, the present invention will be described in detail based on embodiments and in conjunction with the drawings. The drawings are explanatory diagrams showing embodiments of the present invention.

A saturated mother liquor 2 of ammonium sulfate heated to 50 qo was put into the mother liquor tank 1, which had an internal volume equivalent to a saturator, and while being lightly stirred with a rope pestle 3, ammonium nitrate and sulfamic acid were added to the mother liquor tank 1 as a crystallizing agent 4. Ammonium was added to the saturated mother liquor 2 by 5% ammonium nitrate and ammonium sulfamate at a coagulation force of 2, and the top mother liquor containing no ammonium sulfate crystals was supplied by a crystallization tank 5 corresponding to a granulator. . The saturated mother liquor 2A in the crystallization tank 5 is 45
Crystallization was performed while maintaining the temperature at q0 and increasing the supersaturation degree of ammonium sulfate. As a result, ammonium sulfate crystals 6 are precipitated, and as the crystal concentration increases, the crystals 6 are successively separated by the arrow 6 so that the crystal content becomes 25%.
It was extracted as shown in A. The mother liquor containing no ammonium sulfate crystals in the crystallization tank 5 was circulated into the mother liquor tank 1 at a rate of 50 to 100 Z/min by a pump 7. Note that by rotating the crystal tank, the ammonium sulfate crystals have the effect of giving a better roundness.
The properties of the ammonium sulfate obtained at this time are shown in Table 1 in comparison with those obtained by the conventional method in which no crystal modifier was added.

Table 1 As shown in Table 1, according to the method of the present invention in which 5% ammonium nitrate and 2% ammonium sulfamate were simultaneously added as soot crystallizing agents, the particle size of ammonium sulfate was reduced compared to the conventional method in which no crystallizing agent was added. The crystals are large and have a rounded spherical shape, the quality of the ammonium sulfate, the ammonia nitrogen content is almost the same as the conventional one, and the increase in nitrate nitrogen and sulfamic acid is small, so it is highly effective. Ta.

When the amount of ammonium nitrate added according to the present invention is 1% or more, it is possible to make ammonium sulfate crystal grains round.
%, the shape of the crystal grains will be good, but the ammonia nitrogen content will be significantly reduced, so the amount of ammonium nitrate added should be in the range of 1 to 10%.

In particular, addition of about 5% is desirable from the viewpoint of the shape and quality of ammonium sulfate. Also, the amount of ammonium sulfamate added is 0.5
%, the shape of the ammonium sulfate crystals can become large, and if it exceeds 5%, the amount of sulfamic acid increases from the viewpoint of quality of ammonium sulfate. Therefore, the amount of ammonium sulfamate added should be in the range of 0.5 to 5%. In particular, addition of about 2% is desirable from the shape and quality of ammonium sulfate. Although examples of the soot crystallizing agent according to the present invention have been described as ammonium nitrate and ammonium sulfamate, it is also possible to use nitric acid and sulfamate.
When nitric acid and sulfamic acid are added to the mother liquor, they combine with gaseous ammonium to form ammonium nitrate and ammonium sulfamate, which function as crystal modifiers.

In this case, the ratio of nitric acid and sulfamic acid added must be within the above range in terms of ammonium nitrate and ammonium sulfamate. Further, as shown in Table 1, the amount of ammonium nitrate and ammonium sulfamate mixed into ammonium sulfate crystals is small, so the amount of replenishment may be sufficient. As described above, according to the present invention, the shape of ammonium sulfate crystal grains can be made round and spherical, and the particle size can be increased, so that caking of ammonium sulfate can be prevented, and several types of granular fertilizers can be mixed together. This has the effect of being able to respond to the market in which it is used.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention. 1: mother liquor tank, 2, 2A: saturated mother liquor, 3, 3A: fly pestle,
4: Soot crystallizing agent, 5: Crystallization tank, 6, 6A: Crystal, 7: Pump. O diagram

Claims (1)

[Claims] 1. In the process of producing granular ammonium sulfate from an ammonium sulfate mother liquor through a crystallizer, 1 to 10% of nitric acid or ammonium nitrate in the form of ammonium nitrate and sulfamic acid or ammonium sulfamate in the form of ammonium sulfamate are added to the ammonium sulfate mother liquor as a crystallizing agent. A method for producing granular ammonium sulfate, which comprises adding and crystallizing 0.5 to 5% of ammonium sulfate.