EP2599552A1

EP2599552A1 - Ball-less grinding mill

Info

Publication number: EP2599552A1
Application number: EP12194635.4A
Authority: EP
Inventors: Davide Giacometti; Ylenia Giacometti
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-02
Filing date: 2012-11-28
Publication date: 2013-06-05
Also published as: ITGE20110139A1

Abstract

Ball-less grinding mill comprising:
- A containment tank (1);
- A cylindrical stator (4) open at both ends, disposed in said tank (1), from which a plurality of annular members (7) formed at their periphery with a crown of teeth (107, 207) radially protrude toward the center;
- A cylindrical rotor (8) mounted concentrically to said stator (4), and comprising a stack of spacing rings (10) with interleaved discs (11) of greater diameter radially projecting outwardly, each provided at their periphery with a crown of teeth (111, 112);
- The crown of teeth (107, 207) (7) of the annular members (7) of the stator (4) being opposed at a very short distance to, and inserted between the crown of teeth (111, 112) of the of the discs (11) of said rotor (8);
- Motor means for operating said rotor (8);
- A fluid in said tank containing in suspension the raw materials to be crushed;
- And means to continuously circulate said fluid in said tank between the bottom and the top of said stator (4).

Description

The present invention relates to the grinding of raw materials of mineral, animal or vegetable origin, and more particularly it relates to a mill for grinding and dispersing of such raw materials in a liquid or pasty vehicle, such as for example the grinding of the components of water paints, varnishes, or edible mixtures such hazelnut paste, or the like, or cosmetic or pharmaceutical compositions.
Currently for these milling processes, which require the obtainment of solid particles of the size of some microns, the use of mills is forecast making use of the mechanical rubbing action of disks and / or microspheres of glass or glass /zirconium.
These known processes involve quite a few disadvantages. In fact, they require motors of great power, considerable amounts of water and / or solvents for the cleaning of the equipment and long working times.
It is therefore the purpose of the present invention a plant or mill for the grinding and dispersion of raw materials of mineral, animal or vegetable origin in a liquid or pasty vehicle without the use of disks and / or microspheres, which is apt to overcome the drawbacks of the known plants, as claimed in claim 1.
Further objects and advantages of the present invention will better appear during the following description made with reference to the accompanying drawings, in which:

Figure 1 is a diametrical sectional view of a mill according to the invention,
and
Figure 2 is a perspective view of a detail on enlarged scale of a fragment of a disk of the rotor of the mill according to the invention.

With reference to the drawings, and with particular reference to Figure 1, the mill according to the invention comprises a cylindrical tank 1 comprising an outer shell 101 and an inner skirt 201 delimiting between them a hollow space 2. This hollow space 2 communicates with the outside through the tubular fittings 3, 103 for purposes which will be described below.
Numeral 4 denotes the stator of the mill. Said stator comprises a cylindrical body open at both ends and formed by an outer shell 104 and an inner skirt 204 delimiting between them an annular hollow space 5. Said hollow space 5 communicates with the outside through the tubular fittings 6, 106 for the purposes which will be described below.
A plurality of equispaced, radially inwardly extending annular laminae 7 are secured, for example by welding, to the external surface of the inner shell 204, each ending with a peripheral crown of teeth 107, 207 alternately symmetrically bent in one and in the other direction with respect to the plane of the annular laminae 7 such as to include between two adjacent teeth an angle comprises between 10 ° and 20 °.
Numeral 8 denotes the rotor of the mill. Said rotor, the axis of which coincides with the axis of the stator 4, comprises a shaft 9 connected to the drive motor (not shown) of the rotor 8. This shaft 9 ends with an annular flange 209, from the center of which extends the shaft 309. On this shaft 309 are keyed alternately the spacers 10 and the discs 11 each carrying peripherally a crown of teeth 111, 211 similar to the teeth 107, 207 of the annular laminae of the stator 4. Said crowns of teeth 111, 211 extend at a short distance between the crowns of teeth 107, 207 of the annular laminae 7. The stack of spacers 10 and toothed disks 11 is fastened by means of the end fastening member 12, to which a toothed disc 112 is advantageously associated.
The operation of the above described mill is as follows:

By means of a suitable pump (not shown) cooling water is circulated through the fittings 3, 103 into the cylindrical jacket 2 of the tank 1, and through the fittings 6, 106 cooling water is circulated by means of a suitable pump (not shown) through the cylindrical jacket 5 of the stator 4.

The raw material to be ground, as for example a mineral paste and a fluid diluent such as water or a suitable solvent, or the like, are entered into the tank 1.
At this point the motor connected to the shaft 9 of the rotor 8 is started. The use of an inverter is forecast in order to control the number of revolutions of the rotor 8, bearing in mind that the greater the number of revolutions /minute of the rotor 8, the smaller is the grinding time required. The inner diameter of the stator 4 was proportioned to the outer diameter of the rotor 8, so as to reduce as much as possible the interstitial space, so as to maximize the number of collisions between the raw material in the course of being grinded and the teeth of the toothed crowns the annular laminae 7 and of the discs 11.Thanks to the fact that the cylindrical stator 4 is open at both ends, around the stator 4 a circular flow of the product stream is established, which flow is further favored by the presence of the toothed disc 12, and possibly by suitable forced circulation means.
The advantages which can be obtained by the present mill can be summarized as follows:

Drastic reduction of grinding times; reduction of production costs; mechanical grinding of the raw materials at full scale, namely to a degree of fineness which is difficult to be achieved with the microsphere and / or disc mills; ease of cleaning of the mill whenever stepping from the treatment of a product to that of a product totally different, thanks to the absence of the microspheres, with a consequent reduction of production costs. Thanks to the provision of a fluid circulation system in the hollow spaces 2 of the tank and 5 of the stator, it is possible to proceed with the cooling and / or heating of the products being grinded, so that for example it is also possible to grind thermo labile products or products requesting to be heated for their fluidization, such as for example products for the food, cosmetics, pharmaceutical and / or chemical industry.

Thanks to the fact that the stator 4 is open at both ends and, unlike the known prior art devices, it works by immersion, a continuous flow of material under treatment is established there through, which is favored by a natural circulation which optionally can be increased by means of forced circulation such as for example those constituted by the disc 112. This circulation of the material in the course of treatment through the stator 4 accelerates the grinding process and makes the final product absolutely homogeneous.
Therefore the present invention is not limited to the embodiment shown and described, but it includes all those variants and modifications falling within the broader context of the inventive concept, substantially as claimed below.

Claims

Ball-less grinding mill comprising:
- A containment tank (1);

- A cylindrical stator (4) open at both ends, disposed in said tank (1), from which a plurality of annular members (7) formed at their periphery with a crown of teeth (107, 207) radially protrude toward the center;

- A cylindrical rotor (8) mounted concentrically to said stator (4), and comprising a stack of spacing rings (10) with interleaved discs (11) of greater diameter radially projecting outwardly, each provided at their periphery with a crown of teeth (111, 112);

- The crown of teeth (107, 207) (7) of the annular members (7) of the stator (4) being opposed at a very short distance to, and inserted between the crown of teeth (111, 112) of the of the discs (11) of said rotor (8);

- Motor means for operating said rotor (8);

- A fluid in said tank containing in suspension the raw materials to be crushed;

- And means to continuously circulate said fluid in said tank between the bottom and the top of said stator (4).
Mill according to claim 1 in which said means for the circulation of said fluid are natural or forced circulation means
Mill according to claim 1, in which said tank (1) and said stator (4) are formed with a jacket (2; 5) in which a cooling or a heating fluid is circulated.
Mill according to the preceding claims in which the said toothed crowns of the stator (4) and of the rotor (8) are each comprising a plurality of teeth (111, 211; 107, 207) bent alternately symmetrically in one or the other sense with respect to the plane of the crowns (11; 7) so as to include among two contiguous teeth an angle comprised between 10° and 20°.
Mill according to the preceding claims, characterized by the fact that the crown of teeth (111, 211) of the discs (11) are extending between the crown of tenths (107, 207) of the annular crown (7) at short distance there between.