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STIRRER MILL

20200406267 ยท 2020-12-31

    Inventors

    Cpc classification

    International classification

    Abstract

    A stirrer mill for the treatment of flowable grinding stock. The stirrer mill includes a milling container, a milling chamber delimited by the container wall, and a stirring mechanism having a rotor which rotates about a central longitudinal axis and has an inside diameter (d351). Tools, which extend toward the container wall, are attached to the rotor. The stirrer mill also includes an internal stator arranged inside the rotor. A grinding stock discharge channel is formed, between the rotor and the internal stator, through which the grinding stock passes to a separating device and, thereafter, to a discharge line. The milling chamber is at least partially filled with grinding bodies having a diameter (c). Above the internal stator is arranged a separating device with a diameter (d30). The distance (s) between the rotor and the grinding body separating device is given by the relationship: s=0.5.Math.(d351d30)5.Math.c.

    Claims

    1-11. (canceled)

    12. A stirrer mill for the treatment of flowable grinding stock, comprising: a milling container and a milling chamber, which is delimited by a container wall, and a stirring mechanism having a rotor that can rotate about a central longitudinal axis, the said rotor having a diameter (d351), wherein tools are attached to the rotor, which tools extend in a direction toward the container wall, an internal stator, which is arranged inside the rotor, between the rotor and an outer wall of the internal stator a grinding stock discharge channel is formed, the milling chamber is at least partially filled with grinding bodies having a diameter (c), and above the internal stator there is arranged a grinding body separating device with a diameter (d30), and a distance (s) between the rotor and the grinding body separating device is given by the relationship:
    s=0.5.Math.(d351d30)5.Math.c.

    13. The stirrer mill according to claim 12, wherein the distance (s) between the rotor and the grinding body separating device is given by the relationship:
    s=0.5.Math.(d351d30)3.Math.c.

    14. The stirrer mill according to claim 12, wherein distance s2 mm.

    15. The stirrer mill according to claim 12, wherein the grinding body separating device comprises a cylindrical protective sieve.

    16. The stirrer mill according to claim 12, wherein the tools, attached to the rotor, only leave free a small gap to the container wall, the gap between the tools and the container wall having a gap width (b) for which, relative to the diameter (c) of the grinding bodies, the relationship: 4cb6c applies, the minimum gap width (b) is given by 1.0 mmb2.0 mm.

    17. The stirrer mill according to claim 12, wherein scraper tools, that extend toward the rotor, are arranged on the internal stator.

    18. The stirrer mill according to claim 17, wherein the scraper tools arranged on the internal stator overlap one another in a direction of the central longitudinal axis and are arranged on the internal stator in such a manner that when the rotor is driven, the scraper tools exert an impulse directed in a through-flow direction on the grinding bodies.

    19. The stirrer mill according to claim 18, wherein between the scraper tools and the rotor a gap is formed, for the gap width (e) of which, relative to the diameter (c) of the grinding bodies, the relationship: 4ce6c applies, and the minimum gap width (e) is given by: 1.0 mmc2.0 mm.

    20. The stirrer mill according claim 12, wherein second tools are arranged on the container wall, which extend toward the rotor.

    21. The stirrer mill according to claim 12, wherein in the stirring mechanism grinding body return channels are formed for returning the grinding bodies from the area of the grinding body separating device back into the milling chamber.

    22. The stirrer mill according claim 12, wherein the diameter (c) of the grinding bodies is given by: c0.65 mm and preferably 0.02 mmc0.3 mm.

    Description

    BRIEF DESCRIPTION OF THE DRAWINGS

    [0014] Further features, advantages and details emerge from the description of the invention given below, with reference to the drawing, which shows:

    [0015] FIG. 1: A vertical longitudinal cross-section of a stirring mill according to an embodiment of the invention.

    DETAILED DESCRIPTION OF THE EMBODIMENT

    [0016] The stirring mill shown in FIG. 1 comprises in the usual manner a milling container 2 with an interior milling chamber 8. The milling chamber 8 is filled at least partially with grinding bodies 43 (not shown) having a diameter of c. The stirring mill also comprises an internal stator 22 and a rotor 35 that can rotate about a central longitudinal axis 19, the rotor 35 having a diameter of d351. In this case a grinding stock discharge channel 47 is formed between an outer wall 23 of the stator 22 and the rotor 35. Onto the rotor 35 are attached tools 38, which project into the milling chamber 8. In addition, on the container wall 9 are attached second tools 74, which are offset relative to the tools attached to the rotor 35. Above the stator 22 there is arranged in the form of a protective sieve 30 a separating device, which is formed to be rotationally symmetrical relative to the central longitudinal axis 19. The protective sieve 30 prevents grinding bodies 43 from flowing through to a downstream discharge line 31, which is located inside the internal stator 22. Between the protective sieve 30 and the rotor 35 there is a distance s. This distance s can be described by the relationship:


    s=0.5.Math.(d351d30)

    [0017] and can be set in particular by selecting the diameter d30 of the protective sieve 30.

    [0018] If the dimensions of the stirrer mill were increased, until now the distance s between the protective sieve 30 and the rotor 35 was also chosen correspondingly larger. However, unexpectedly this does not result in a proportional increase of the production flow. Rather, production remains below expectations.

    [0019] The reason for this is that during operation it can happen that due to drag forces and despite a device for holding back the grinding bodies 43, the latter aggregate against the protective sieve 30. This can result in a reduction of the through-flow or even to complete clogging of the sieve.

    [0020] In order to effectively prevent this, the distance s between the protective sieve 30 and the rotor 35 is reduced. Here, regardless of the structure of the stirrer mill, the distance s can be chosen as a function of the diameter c of the grinding bodies. This results in greater permeability of the stirrer mill, since the risk that grinding bodies 43 might aggregate against the protective sieve 30 is reduced, and hence the breaking up of coarse grains in the product to be dispersed is more rapid.

    [0021] According to the invention, the distance s between the protective sieve 30 and the rotor 35, as a function of the grinding body diameter c, is given by:


    s5.Math.c


    or


    0.5.Math.(d351d30)5.Math.c.

    [0022] In a further preferred embodiment the distance s between the protective sieve 30 and the rotor 35, as a function of the grinding body diameter c, is given by:


    s3.Math.c.

    [0023] In a further preferred embodiment, even independently of the size of the grinding bodies the distance s is no larger than 2 mm.

    [0024] Although the previously outlined example embodiment of a stirrer mill shows a vertical central longitudinal axis 19, the designs described can be used without problems in a horizontal position or in a position between those positions.