JPS5849605A - Granulation of sodium percarbonate - Google Patents

Abstract

PURPOSE:Raw materials are transferred to the kneading zone equipped with groups of paddles by means of the screw where the flat-type paddles mainly effect kneading, ordinary helical paddles effect kneading and extruding and reverse helical paddles effect back mixing and kneading, thereby the hardness and solubility of the product are improved. CONSTITUTION:Two stirring shafts 1, 1' are set in parallel in the twine-hulled split trough 2 so that they revolve in the same direction. These shafts are provided with screws, flat paddles and other paddles with the convex cross section or triangular or more polygonal cross section, ordinary helical paddles and revesed helical paddles. A mixture of sodium percarbonate powder, additives and water is fed, sent by the screw to the kneading zone equipped with the above groups of paddles to make granules and then, the granules are taken out of the outlet 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for granulating soda percarbonate, and relates to a method for granulating powdered sodium percarbonate into granules by continuously mixing and kneading it in a wet state.

Sodium percarbonate is easily obtained by reacting sodium carbonate with hydrogen peroxide, and is used as a bleaching agent. When powdered soda percarbonate scatters, it irritates the pot, making it undesirable to handle, and fine powder tends to solidify when stored for a long period of time, making it extremely difficult to maintain a smooth state. In addition, sodium percarbonate is unstable to moisture, and the content of active oxygen in it tends to decrease due to moisture, and it is desirable to reduce the area of contact with moisture, so it is generally produced in granular form. It is grained.

Conventionally, granulation of sodium percarbonate has been carried out using an extrusion granulator, which is mixed and kneaded in the presence of water and additives such as a suitable binder, and then extruded through a perforated plate using the well-known Nigu method, or a Henschel mixer type. A type of granulator is generally used.

However, although the above-mentioned extrusion granulation method in which extrusion is performed through a perforated plate yields granulated products with a relatively uniform shape, the resulting granulated products are hard, and due to the limitations of the pore size of the perforated plate, the particles are large and soluble in water. The speed is slow. Furthermore, the perforated plate tends to have a single hole, which requires frequent replacement of the perforated plate, making it difficult to operate continuously. Also,
Henschel mixer type granulators have the advantage of granulating in a short time and generating less frictional heat, but on the other hand, the granulated particles are soft and brittle and are easily crushed during transportation. , and also has drawbacks such as a small height increase of 3fL.

On the other hand, various types of devices for mixing and kneading are known that are equipped with two screws that rotate and mesh with each other in a container, and that continuously knead and knead materials. Even if sodium percarbonate is granulated using this known device, particles that fully satisfy all of the particle size, hardness, bulk specific gravity, dissolution rate, etc. cannot be obtained.

The present invention was made in view of these various drawbacks, and the granulator of the present invention is capable of continuously carrying out mixing and kneading granulation in one stage without any pretreatment. The object of the present invention is to provide a granulation method for producing granular sodium percarbonate, which is capable of producing particles with sufficient particle size, hardness, bulk specific gravity, and dissolution rate in water.

In the present invention, two stirring shafts that rotate in the same direction are arranged in parallel in a double-barreled trough, and each shaft has a screw and a cross-sectional shape of a convex lens shape or a pseudo-triangular shape or more. A paddle having a polygonal shape of It has a structure in which the tip of the paddle installed on the trough always rotates while keeping a small gap in contact with the inner surface of the trough and the paddle surface installed on the other shaft, and has a material supply port and a material discharge port. The present invention relates to a method for granulating soda percarbonate, which is characterized by using a mixed-wire, kneading, and granulating machine.

To further explain the granulator used in the present invention, as described above, a group of paddles having a cross-sectional shape of a convex lens shape or a polygon of pseudo-triangle or more is installed on the stirring shafts arranged in parallel in the trough. There is.

The paddle includes a flat paddle with a flat side surface,
There is also a helical paddle that has a spiral shape. There are two types of helical type: a forward helical type that has the effect of mixing and pushing, and a reverse helical type that has the effect of reverse feed. These paddles can be combined appropriately to form a group of paddles on two stirring shafts. The feed that has been pushed and transferred by the screw can be crossed and kneaded by repeatedly pushing and returning by the cough paddle group.

In addition, the tip of the cross-sectional shape of any of the paddles mentioned above is
Either one with a pointed end or one with a flat end is acceptable.

Therefore, by using the above-mentioned granulator,
Soda percarbonate powder, additives, supplied from the material supply port
The supplies such as the binder liquid and water are transferred to the mixing and kneading area where the paddle group is arranged by a screw with sufficient pushing force, and the flat paddles in the paddle group mainly perform mixing. The forward helical paddle performs mixing and pushing, and the reverse helical paddle performs return and mixing, and the granules are forcibly stirred, mixed, and kneaded in the trough.

Sodium percarbonate granules can be obtained by sizing using a sizing machine equipped with a rotating knife cutter.

Next, the kneading and kneading granulator according to the present invention will be explained in more detail with reference to the attached drawings.

The granulator in the present invention is a continuous kneading and kneading granulator that has a self-cleaning effect on the inner surface of the trough and the paddle surface 6- as the shaft 1°1' rotates as shown in the figure. A jacket is provided on the outside of the trough so that cooling water can be conducted therethrough, and a structure is also provided that allows cooling water to be conducted inside the shaft. Figure 1 is a partially cutaway side view of a granulator equipped with a paddle with a convex lenticular cross-sectional shape, Figure 2 is a cross-sectional view of the paddle at the T-1 cross section in Figure 1, and IBI is a TI in Figure 1
-N cross-sectional views of the paddles in the horizontal plane are shown, respectively. FIG. 6 is a partially cutaway side view of a granulator equipped with a paddle having a pseudo-triangular cross-sectional shape, and FIG. 4 is an I-T in FIG.
II shows a view of the paddle in cross section. In the drawing,
1.1' is the stirring shaft, 2 is the trough, 3 is the cooling water conduction part, 4
4' is a paddle with a convex lens cross section, 5.5' is a paddle with a solid triangular cross section, 6 is a material supply port, 7 is a discharge port, and 8 is a mantle.

The two stirring shafts 1.1' each have a specially shaped paddle,
For example, a convex lens cross-sectional shape, or a flat type, helical type, or reverse helical type paddle with a polygonal shape larger than a pseudo-triangle can be installed in an appropriate combination! It is L. The residence time of the granulated material that is kneaded and kneaded can be adjusted by the combination of the paddles, and as a result, the volume of the granulated material is 1! The degree of hardness, hardness, etc. are adjusted as appropriate.

The details of this paddle combination are as follows: Helical paddle (& kneading, feeding) - Flat paddle (mixing) - Helical paddle - Reverse helical paddle (return) -
It is a combination of a helical paddle, a flat-eye paddle, a helical paddle, and a reverse helical paddle.

In the granulator according to the present invention (i), in the paddle combination number (a) and (c), the area near the discharge port must be a reverse helical type paddle, but in the intermediate paddle combination, a reverse helical type paddle is required. is necessary (it is installed accordingly). When applying strong kneading, the number of inverted helical paddles installed in the middle is increased. In such a case, a hard granulated product with a relatively high bulk density can be obtained. On the other hand, if the number of reverse helical I shaped paddles is reduced, a granulate with a relatively low bulk density can be obtained.Furthermore, the rotational phase of each paddle is usually set on the axis with a lag of 45 degrees, but other It can also be installed on the axis with a delay of 60 degrees or 90 degrees.

The granules granulated by the granulator as described above are discharged from a discharge lower, and then, although not shown, after being sized by a granulating machine equipped with a knife cutter that rotates at high speed,
It is dried and made into a product. This granulating machine has two blade-like knife cutters attached to the rotating shaft in a stack of 8 to 12 blades at appropriate intervals, and a lid equipped with a hopper for introducing granules with a length of 25 to 150 cm. The cough knife cutter consists of a bottomless cylindrical container with a slight gap between the tip of the blade and the inner wall of the cylinder.
It is rotated at high speed at 000 to 40 o o r, p, rn.

When the number of knife cutters is the same, the average particle diameter becomes smaller as the rotation speed becomes faster and the length of the cylindrical container becomes longer. For example, if the length of the cylindrical container is 25 fins, the number of knife cutters is 8, and the number of rotations is 400 Or, p, m9-, the average diameter of the particles obtained is 610μ, and the length of the cylindrical container is When is 150m, the average particle size obtained is 430μ. Furthermore, when the length of the cylindrical container is the same and the rotational speed is the same, the average particle size tends to decrease as the number of knife cutters increases. For example, rotation speed 4
When the length of the cylindrical container is 150mm and the number of knife cutters is 12, the average particle size is 340μ.

Among the various physical properties of the granulated product obtained by the method of the present invention, the bulk specific gravity, hardness, dissolution rate, etc. of the particles are mainly influenced by the conditions of kneading and kneading during granulation in the granulator. , the particle size is determined by the conditions of the sieving machine.

The product granulated by the method of the present invention has excellent hardness and solubility, and can be produced with any desired bulk specific gravity and particle size.

Next, examples of the present invention will be shown.

10-Example A kneading and kneading granulator having the same structure as shown in the figure was used. Particle size: 50-100μ, water content: 18-10μ, raw material sodium percarbonate, 100 t/hr from material input port 6, 15% sodium metasilicate solution as a mouth agent (binder water: 110 t/hr).

was supplied. Screw rotation speed 120r, pom.

Mixing, kneading, and granulation were performed using the same paddle combination as in FIG. 6. In addition, cooling water was passed through a conduit inside the jacket of the container and the screw shaft. One hour after the start of operation, six stable grains were obtained. Then, the obtained granules were heated at 400 Or, p,
Length 150 of a cylinder with a knife cutter rotating at m
After sizing using a preparatory sizing machine, it was dried to obtain a product.

The physical properties of the product were as follows.

[Brief explanation of the drawing]

Figures 1 and 5 each show an open side view of a part of the granulator according to the present invention, and Figure 2 (Al is an IT cross-sectional view in Figure 1, and (B) is a cross-sectional view in Figure 1). TI in
-II cross-sectional view is shown, and Figure 4 shows III in Figure 3.
-III shows a cross-sectional view. 1.1'...axis, 2...trough, 3.
...Cooling water conduction part, 4.4', Paddle...Convex lens cross-sectional shape, 5.5'...Paddle with pseudo-triangular cross-sectional shape Patent applicant Mitsubishi Kawara 11i Chemical Co., Ltd. Representative Kazu Nagamachi 13--

Claims (1)

[Scope of Claims] 1) Two stirring shafts rotating in the same direction I are frozen in a double-barreled trough,
Yo7. Ryu, cross section. Shape force 5: A paddle having a lens shape or a polygon larger than a pseudo-triangle is installed, and a flat paddle, a helical paddle, and an inverted T-shaped paddle are appropriately arranged on a pair of shafts, and the shafts are rotated simultaneously. The structure is arranged so that when the blade is rotated, the tip of the paddle installed on one shaft is always in contact with the inner surface of the trough and the paddle installed on the other shaft with a small gap in the cross section perpendicular to the shaft. A method for granulating a percarbonate hoop, which uses a kneading and kneading granulator equipped with a material supply port and a discharge port. 2) The method according to claim 1, wherein the kneading/kneading granulator is a kneading/kneading granulator having an inverted helical paddle in the vicinity of the discharge port.