JPH0464733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the granulation of powder, particularly to a method for producing spherical particles.

[Prior Art] It is well known that, from the viewpoint of particle shape, the fluidity of granules is better when they are more spherical than when they have an acute-angled shape. Particularly, in the case of granules used for fertilizer, the particle shape is required to be spherical from the viewpoint of fertilization.

As a method for producing granules from powder, compacting is used to compression mold the powder using a pair of flat rolls to form flat granules, which are then crushed using a crusher to obtain irregularly shaped granules. Alternatively, a powder material is compression molded with a pair of rolls having a large number of concave portions (hereinafter referred to as "pocket holes") on the surface, and a large number of convex portions (hereinafter referred to as "tablets") corresponding to the pocket holes of the rolls are formed. ) After forming a plate-shaped product, it is crushed in a crusher, and briquetting is generally performed to obtain particles having a shape corresponding to the pocket hole of the roll.

However, in the former compacting,
It is difficult to obtain particles with a constant shape, and only irregularly shaped particles are obtained. In addition, in the latter type of briquetting, the board that connects the tablets remains around the entire periphery of each tablet as a so-called "burr", and the compression ratio of this "burr" part is larger than that of the tablet part, and the tablet is compressed harder than the tablet part. ing. For this reason, it is difficult to completely remove this "burr", and even when molded using a roll with hemispherical pocket holes, the shape of the particles obtained as a product is difficult to become spherical. Another drawback is that if the compression ratio of the spherical portion is increased, crushing becomes impossible.

[Problems to be Solved by the Invention] The present inventors have proposed a method for improving press rolls and crushers to obtain granules that are truly close to spheres.
The present invention was arrived at as a result of various studies.

[Means for Solving the Problems] That is, the present invention, in producing a granular material from a powdery material, uses a pair of press rolls having continuous grooves along the circumferential direction to move the powdery material, The powder is compression-molded using press rolls with symmetrical grooves on each roll, and the resulting string-like material is rolled into gear-like rolls with sharp protrusions at regular intervals. The object of the present invention is to provide a granulation device that obtains granules from a powdered material by cutting it into granules using a granulator.

In the present invention, the string-like molded body includes a gear-like roll having acute-angled protrusions at regular intervals;
It is preferable to cut the sheet using a flat roll facing the sheet.

In the present invention, the interval at which the string-like material is cut is such that the cutting length of the string-like material is 0.5 to 1.5 with respect to the thickness of the string-like material in the direction compressed by the press roll.
It is preferable to double the amount. In this case, it is preferable because particles having a shape close to a sphere can be easily obtained when milled in a later step.

Next, an example of a manufacturing apparatus according to the present invention will be explained with reference to the drawings.

FIG. 1 shows details of the manufacturing apparatus. The powdered material 2 supplied to the raw material hopper 1 is compressed and molded by press rolls 3 and 3' to form a string-like molded material 4.
becomes. The press rolls 3 and 3' are as shown in the figure.
For example, semicircular grooves corresponding to a desired grain size are cut along the circumferential direction, and a large number of these grooves are connected in the direction of the axis of the press roll. Between adjacent grooves, the width of the flat plate part of the roll between the grooves is
It is preferably 1.0 times or less the maximum depth of the groove.
The grooves on the press rolls 3 and 3' are made in a symmetrical shape. For example, when semicircular grooves are dug in the rolls, at the place where the two rolls come into contact,
It will form a circle. If the grooves on both rolls are not symmetrical, the string-like material will be crimped onto whichever has greater frictional resistance, resulting in insufficient release from the rolls. The string-like connected material compression-molded by the press rolls 3, 3' is guided by a guide 7 and supplied to the cutting rolls 5, 5'. The cutting roll 5 is a gear-shaped roll having convex portions with acute angle tips at regular intervals, and the cutting roll 5' is a flat roll having the same outer diameter as the cutting roll 5. The clearance of the cutting rolls 5, 5' is determined by the press roll 3,
By making the thickness slightly smaller than the maximum thickness of the compression-molded string-like molded product in step 3', the string-like connected material is cut into a length that follows the pitch of the convex portion of the cutting roll 5.
It becomes a cylindrical pellet. The shape of the pellets does not necessarily have to be cylindrical, but can be elliptical or cylindrical.
The pellets may have a shape such as a rectangular parallelepiped, but in order to make them into spheroidal particles in the next step, the ratio of the thickness and length of the pellets must be
A value of 0.5 to 1.5 is desirable.

The pellets thus obtained can be easily made into spherical particles by grinding them using a known technique (for example, Marmerizer manufactured by Fuji Paudal Co., Ltd.).

Examples of manufacturing using the apparatus according to the present invention are shown below.

Example 1 Powdered ammonium chloride under 32M'e was fed into a press roll to obtain a string-like molded product. The press rolls consisted of a set of two rolls having semicircular grooves of R=1.9 mm along the circumferential direction, and the rolls were operated at a peripheral speed of 0.2 m/sec. The string-like molded product obtained at this time is shown in FIG.

The string-like molded product formed by the press roll was then guided by a guide and introduced into a cutting roll operating at a circumferential speed of 0.8 m/sec. The cutting roll consisted of a gear-shaped roll with a pitch of 4.9 mm and an acute-angled protrusion at the tip, and a flat roll with the same diameter as this roll, and the clarity of these two rolls was adjusted to 3.0 mm. .

The obtained pellets had a diameter of 3.8 mm and a cutting length of 4
The cylindrical pellets are ~5 mm in diameter and are shown in FIG.

This cylindrical pellet is further introduced into a grinding device (Marumerizer manufactured by Fuji Paudal Co., Ltd.), and the diameter of the pellet is
The particles became spherical particles with a size of 2.0 to 3.6 mm. The obtained spherical particles had a hardness of 2.0 kg/an angle of repose of 37° as measured by a Kiya hardness tester. This particle is shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a bird's eye view showing one example of the device of the present invention. FIG. 2 is a sketch showing a string-like molded product which is an intermediate of granules produced by the apparatus of the present invention. Figure 3 shows
FIG. 3 is a sketch showing a cylindrical pellet obtained from the string-like molded product of FIG. 2. FIG. 4 is a sketch showing spherical particles obtained from the cylindrical pellets of FIG. 3.

Claims (1)

[Claims] 1. Powder material is compressed by a pair of press rolls having continuous grooves along the circumferential direction, the grooves of each roll being symmetrical. A granulating device for obtaining granules from powder by molding and cutting the obtained string-like material into granules by using a gear-like roll having an acute-angled protrusion at a constant interval. 2. The granulating device according to claim 1, wherein the width of the flat plate portion between the grooves of the press roll is 1.0 times or less the maximum depth of the grooves. 3. The granulation device according to claim 1, which cuts the string-like material obtained by compression molding so that the cutting length is 0.5 to 1.5 times the thickness in the direction of compression. 4 Using a gear-shaped roll having sharp convex portions at regular intervals and a flat roll facing it,
A granulating device according to claim 1, which cuts a string-like material.