Abstract:
A closure system for ball mills, a method for opening and closing ball mills, and a ball mill including a milling vessel with an end opening which can be closed by a closure mechanism. The closure mechanism assigned a first flange with first connecting devices, and the end opening of the milling vessel assigned a second, mating flange with second connecting devices. The closure mechanism can be fastened on the milling vessel via the first and the second connecting devices.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a closure system for ball mills and a method for opening and closing ball mills. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a closure system for large horizontally orientated ball mills. The ball mill is a device for the coarse, fine and extremely fine size-reduction or homogenisation of grinding stock. It comprises a grinding chamber, which is caused to rotate and in which grinding stock is size-reduced by grinding bodies. Ball mills are usually constituted by an approximately circular-cylindrical grinding container mounted horizontally rotatable. The mills are filled through a central opening in one of the end walls. The discharge is dependent on the design and takes place for example through slots in the grinding chamber wall at the end of the mill, the grinding bodies being held back. 
         [0003]    A special form of the ball mill is the agitator ball mill. Agitator ball mills comprise a usually approximately cylindrical grinding container disposed vertically or horizontally, which is filled up to 70-90% with grinding bodies. The grinding container is usually mounted stationary, non-rotating in the case of agitator ball mills. An agitator with suitable agitator elements provides for the intensive movement of the grinding bodies. The grinding stock suspension is continuously pumped through the grinding chamber. The suspended solids are size-reduced or dispersed by impact or shearing forces between the grinding bodies. The separation of grinding stock and grinding bodies takes place by means of a suitable separation system at the discharge of the mill. 
         [0004]    A ball mill is disclosed for example in U.S. Pat. No. 2,542,482 A. The latter comprises a rotatable drum with two circular side faces. One of the circular side faces forms the lid, which is screwed onto the drum. An analogously constituted fastening of the lid is found for example in U.S. Pat. No. 4,018,393 A. 
         [0005]    The lid of large mills, for example of ball mills or agitator ball mills, with a diameter of the grinding container of several metres, has a great weight on account of its size, which makes closing of the grinding container difficult. In the case of an agitator ball mill, the agitator and the drive are usually disposed on the lid, as a result of which the latter is even heavier and more difficult to handle. However, the lid must be able to be repeatedly removed as quickly and easily as possible in order for example to clean the inside of the grinding container, to replace defective stirring means of the agitator, to replace defective and/or worn parts of the grinding container lining, to replace the grinding balls in the grinding container etc. For this reason, ball mills are known wherein the grinding container is mounted horizontally displaceable and can be moved away from the lid. Such and similar mills are known for example from DE 69525334 T2 and WO 2010068993 A1. The grinding container and the lid conventionally comprise flanges, which comprise for example aligned openings so that the grinding container and the lid can be screwed together via the flanges. Long working times spent on removing the screws are in particular a problem when removing of the lid. The problem is compounded, on account of the size, by the difficult accessibility of the screws, especially at the upper and lower side of the flanges. 
         [0006]    The problem underlying the invention is to provide a closure device for a ball mill, with which the lid can be fastened reliably, firmly and in a sealing manner on the ball mill and wherein the lid can be removed from the grinding container quickly and easily, in order to permit easy and simple access to the interior of the grinding container. Furthermore, it is based on the problem of providing a method for the simple, rapid and reliable closing and opening of a ball mill. 
         [0007]    The above problems are solved by a closure system for ball mills and a method for opening and closing ball mills according to the invention. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention relates to a closure system for ball mills with a horizontally or vertically mounted grinding container. Within the scope of application, the term ball mill is used both for ball mills with a rotating grinding container as well as for agitator ball mills with a non-rotating grinding container and agitating tools. In the case of agitator ball mills, the grinding container can be mounted rotatable as well as non-rotatable. The grinding container comprises an end-face opening. In particular, the grinding container is a hollow cylinder open on one side, which is disposed horizontally and comprises a circular opening at one of the free ends. Other geometries of the grinding container, for example containers with a largely symmetrically polygonal, in particular an octagonal cross-section or similar, are also conceivable and are intended to be covered by the invention. The opening is closed with a closure device, in particular with a lid. For this purpose, the closure device comprises a first flange with first connecting devices. The end-face opening of the grinding container comprises a second counter-flange with second connecting devices. The closure device can be fastened to the grinding container in a friction-locked manner by means of the first and the second connecting devices. 
         [0009]    According to the invention, the first or the second connecting devices are each a component part of at least one rotatable, at least partially annular adjustment element. When the adjustment element is mentioned below in the singular, this is also intended to include a plurality of rotatable, partially annular adjustment elements, in particular a plurality of adjustment elements which together broadly form a ring shape. 
         [0010]    The adjustment element can occupy an open working position, in which the first and second connecting devices engage loosely into one another. By rotation in a first direction of rotation, the at least one, at least partially annular adjustment element is transferred into a closed locking position. In this second closed locking position, the first and second connecting devices are rotated towards one another. In particular, the first or the second connecting devices are rotated with respect to the first working position. By virtue of means producing a friction-locked connection, a clamped operative connection between the closure device and the grinding container is constituted in a friction-locked manner. 
         [0011]    The rotation of the adjustment element is a rotary motion of only a few degrees, for example the adjustment element rotates through a rotation angle between 5° and 20°, in particular through approx. 10°-15°. The closure device and the grinding container are pressed axially in the end position by the rotation of the adjustment element in combination with means producing a friction-locked connection, so that the closure device is fastened to the grinding container in a sealing manner. 
         [0012]    The grinding container is preferably horizontally mobile, whilst the closure device is disposed for the most part stationary. For the fastening of the closure device on the grinding container, the latter is moved into a first closure position, in which the first connecting devices of the closure device and the second connecting devices of the grinding container flange engage loosely into one another, or in which the second connecting devices of the grinding container flange engage through the first connecting devices of the closure device. The locking then takes place by the rotation of the adjustment element and the means producing a friction-locked connection. In order, for example, to clean the grinding container or to remove grinding bodies etc., the locking between the grinding container and the closure device is released, wherein the adjustment element is rotated in the opposite direction to the first direction of rotation and the friction-locked and/or form-fit connection via the means producing the friction-locked connection is removed. After the rotation of the adjustment element in the opposite direction, the first and second connecting devices are disposed in such a way that they engage only loosely into one another. By a horizontal movement of the grinding container away from the closure device into a maintenance position, easy access to the interior of the grinding container is enabled. 
         [0013]    For the adjustment of the at least one rotatable, at least partially annular adjustment element by rotation, there is assigned to the latter at least one suitable hydraulic, pneumatic and/or electronic adjusting means, in particular at least one hydraulic device. According to a preferred embodiment, provision is also made such that centring means are assigned to the flange and the counter-flange, which force the correct alignment of the closure device at the grinding container and thus also prevent wedging of the first and second connecting devices. For example, the flange comprises a centring pin, which engages and is guided in a corresponding bore of the counter-flange. At least two centring pins are preferably provided in order that the grinding container and the closure device are properly aligned with one another when they are brought together. Further centring means known to the person skilled in the art are also intended to be covered. 
         [0014]    According to a first embodiment of the invention, the first connecting devices of the closure device are a component part of a rotatable, annular adjustment element. In a first open working position of the adjustment element, the first connecting devices are located in a first open position aligned with the second connecting devices. If the grinding container is now displaced horizontally along its longitudinal axis in the direction of the closure device, the second connecting devices of the grinding container loosely engage in the first connecting devices of the closure device, or engage through the latter. By rotation of the adjustment element, the latter is transferred into the locking position. The first connecting devices are thereby rotated into a second, at least partially closed position. In the second locking position of the adjustment element, the first and the second connecting devices are rotated at least partially towards one another. The first and the second connecting devices are preferably rotated towards one another to an extent such that they are no longer aligned parallel with the longitudinal axis of the grinding container, but are disposed at least for the most part beside one another. 
         [0015]    The rotatable, annular adjustment element is constituted for example as an external ring, which is assigned rotatably to the first flange of the closure device. The external diameter of the external ring is preferably constituted greater than the external diameter of the first flange. According to alternative embodiment, the external diameter of the external ring is preferably constituted identical to the external diameter of the first flange. The external ring comprises inwardly directed first teeth, i.e. the first teeth of the external ring are directed towards the ring centre-point of the external ring. In particular, a plurality of identically constituted first teeth are disposed uniformly spaced apart at the internal diameter of the external ring, so that the latter form a kind of internal ring gear. The gaps between the first teeth each form the first connecting devices. At least one free space is constituted at least in regions between the first teeth and the first flange. This free space is preferably constituted with a size such that the second, subsequently described teeth of the grinding container flange can be pushed completely into the gaps between the first teeth. Alternatively, the first teeth can have an undercut constituted towards the first flange. The second connecting devices project in regions beyond the external diameter of the grinding container flange. In particular, the second connecting devices are constituted as outwardly directed second teeth. A kind of external ring gear is disposed on the grinding container flange. The second teeth are dimensioned such that, in a first working position, they can be pushed by the horizontal displacement of the grinding container into or through the gaps between the first teeth, i.e. between the inwardly directed first teeth of the adjustment element of the closure device. Second connecting devices are correspondingly pushed into first connecting devices, which are a component part of the adjustment element of the closure device. For this purpose, the grinding container is moved towards the closure device to an extent such that the second connecting devices for the most part abut against the flange of the closure device. 
         [0016]    The locking position is adjusted by rotating the closure element in a first direction of rotation. The first direction of rotation is defined for example as the closing direction of rotation in the clockwise direction. When the closure element is rotated in the clockwise direction, the first connecting devices are rotated with respect to the second connecting devices. In particular, the first teeth of the rotatable, annular adjustment element are pushed at least partially over the second connecting devices, i.e. over the outwardly directed second teeth of the grinding container flange. The second teeth are then disposed at least partially in the free space or in the undercut between the first, inwardly directed teeth of the external ring and the flange of the closure device. Preferably, the first teeth for the most part completely overlap the second teeth in the locking position of the adjustment element. 
         [0017]    In order to generate a particularly good friction-locked connection, wedge elements can be assigned to the second connecting devices on the side facing the grinding container, said wedge elements widening normal to be grinding container flange against the first direction of rotation of the external ring of the closure device. Alternatively or in addition, wedge elements can also be disposed on the lid side of the first teeth. The wedge elements on the first teeth are referred to below as the first wedge elements and the wedge elements on the second teeth are referred to as the second wedge elements. 
         [0018]    When the first wedge elements on the first teeth of the closure device are viewed from the container side, their thickness increases normal to the plane of the open end face of the grinding container in each case in the anticlockwise direction. When the open end face of the grinding container is closed with the closure device, the first wedge elements together with the second wedge elements of the second teeth disposed on the grinding container flange bring about the creation of a friction-locked connection, in particular since the contact pressure is additionally increased by the respective widening of the first and second wedge elements. 
         [0019]    According to an embodiment of the invention, provision is made for the first or the second wedge elements to be disposed displaceably on the first or second teeth. An adjustment can be made for example by means of a slotted-hole fixture or other suitable adjustment options. The wedge elements are preferably adjusted once when the ball mill is put into operation. Alternatively and/or in addition, provision can be made to readjust, if need be, the adjustable wedge elements, for example when the sealing elements become thinner, in order always to ensure a sufficient friction-locked connection. 
         [0020]    In this connection, it should also be pointed out that it is of course advisable to constitute the wedge elements so as to be individually exchangeable, so that the latter can each be exchanged individually in the event of damage. 
         [0021]    When the second locking position is adjusted by the rotation of the adjustment element, the wedge elements enhance the friction-locked connection between the first inwardly directed teeth of the external ring of the adjustment element of the closure device and the second outwardly directed teeth of the grinding container flange. By rotating the adjustment element into the closed locking position, an additional pressure is produced by the wedge elements in the axial direction of the grinding container. A sealing element, for example in the form of a rubber seal or an approx. 10 mm to 15 mm thick rubber sheet, is preferably assigned to the closure device on the grinding container side. As a result of the additional pressure in the axial direction, the rubber seal or rubber sheet is compressed and the grinding container is thus sealed against the closure device. According to an embodiment of the invention, the sealing elements are wearing parts. 
         [0022]    The grinding container including the grinding container flange, the closure device and the rotatable external ring with the first teeth are preferably made of a first material, in particular of steel or special steel. The wedge elements on the second connecting devices are preferably made of a second different material, for example of brass or a copper-zinc alloy etc. The material of the wedge elements is selected such that there is the least possible adhesive friction between the material of the external ring and the material of the wedge elements. As a result of a low adhesive friction, for example as a result of a low adhesive friction between brass and steel, undesired jamming does not therefore occur during the rotation of the external ring. 
         [0023]    For the rotation of the rotatable, annular adjustment element according to the first described embodiment, two hydraulic cylinders, for example, are provided, which are disposed on the rotatable, annular adjustment element and on a frame carrying the ball mill and bring about the necessary rotation of the adjustment element. 
         [0024]    According to a second embodiment of the invention, a plurality of rotatable, partially annular adjustment elements with two connecting devices are assigned to the grinding container flange. Four largely quarter-circle-shaped adjustment elements are preferably provided. In an open working position of the adjustment elements, the second connecting devices are located in a first open position, so that the first connecting devices of the closure device can engage in an aligned manner through the second connecting devices. The second connecting devices are transferred into a second closed position by preferably simultaneous and joint rotation of the adjustment elements. Provision can be made here such that all the adjustment elements rotate in a common direction of rotation. Alternatively, provision can be made such that some of the adjustment elements rotate in the clockwise direction and the other adjustment elements in the anticlockwise direction. Additional axial displacement devices are assigned to the first connecting devices, by means of which axial displacement devices the first connecting devices can be displaced parallel to the longitudinal axis of the grinding container. Hydraulic, pneumatic or electric means known to the person skilled in the art can be used as an axial displacement device. To close the grinding container, the latter is moved towards the closure device, so that the flange and the counter-flange almost make contact. The grinding container is usually moved so close to the closure device that a gap between 5 mm to 40 mm, preferably between 10 mm to 25 mm, is constituted between the grinding container and the closure device, said gap being uniform and running around the entire circumference. The first connecting devices thereby engage through the second connecting devices. The first connecting devices can also be displaced or extended in the direction of the grinding container, subsequently or largely simultaneously, by means of their respective axial displacement devices. Hydraulic cylinders, for example, or other suitable means serve as axial displacement devices. The axial displacement devices can be controlled individually or jointly. In this second embodiment, the axial displacement devices at the same time represent the means producing the friction-locked connection, as will be explained in the following. 
         [0025]    The first connecting devices are constituted for example as hydraulically extendable bolts with a widened free end region, in particular a widened mushroom-like end region. The first connecting devices are passed through the second connecting devices, if need be with the aid of the axial displacement devices, in such a way that the widened free mushroom-like end regions are located behind the second connecting devices, i.e. behind the adjustment elements on the grinding container flange. The second connecting devices comprise a through-passage region and a support region with a support face for the widened end region of the first connecting devices. The through-passage region and the support region are connected to one another via a central region. The central region is constituted for example as a slotted hole. In the working position of the rotatable, partially annular adjustment elements, the second connecting devices are aligned in such a way that, when the grinding container is moved towards the closure device, the first connecting devices can simply be pushed through the through-passage regions of the second connecting devices. By rotating the partially annular adjustment elements into the locking position, the second connecting devices are displaced via the slotted hole with respect to the first connecting devices in such a way that the free end regions of the first connecting devices are now each positioned in front of the support regions of the second connecting devices. By means of the hydraulic cylinders, the first connecting devices are drawn towards the closure device. The widened end region is thus pressed against the support face of the second connecting device and a contact pressure is produced between the widened end region and the support region of the second connecting device and thus a friction-locked connection between the grinding container and the closure device, as a result of which the grinding container can be moved up completely to the closure device and thus closed with the latter firmly and in a sealing manner. 
         [0026]    The first connecting device, i.e. the bolt with the widened mushroom-like end region, can for example be constituted such that it can easily be detached from the respective hydraulic cylinder. The bolt is guided in a socket and screwed with the hydraulic cylinder. 
         [0027]    According to an alternative embodiment, provision is made such that not every first connecting device has its own hydraulic cylinder assigned to it as an axial displacement device, but that a plurality of first connecting devices are coupled with one hydraulic cylinder and are thus adjusted jointly. For example, provision is made such that three bolt-shaped first connecting devices each with a widened mushroom-like end region are each assigned to a common hydraulic cylinder. 
         [0028]    For the rotation of the rotatable, partially annular adjustment elements, suitable hydraulic, pneumatic or electronic means are assigned to each of these elements. For example, at least one hydraulic cylinder, preferably two cooperating hydraulic cylinders are assigned in each case to the adjustment elements. The rotation of the adjustment elements for the opening or closing of the closure system preferably takes place largely synchronously. 
         [0029]    The adjustment, i.e. the rotation of the adjustment elements and/or the application of the friction-locked connection by means of the axial displacement devices, can also take place pneumatically and/or electronically. 
         [0030]    The invention also relates to a method for opening and closing a ball mill, wherein the ball mill comprises a horizontally disposed grinding container with an end-face opening, which can be closed with a closure device. The ball mill further comprises a closure system with at least one rotatable, at least partially annular adjustment element with first connecting devices on the closure device or with second connecting devices on the grinding container. In particular, the ball mill comprises a closure system according to the first or second embodiment described above. 
         [0031]    In a working position, the first and the second connecting device engage in an aligned manner into one another and the first connecting devices engage in an aligned manner through the second connecting device or the second connecting devices engage in an aligned manner through the first connecting devices. The at least one adjustment element is transferred by rotation into a closed locking position. During this rotation of the at least one adjustment element, the first and second connecting devices are rotated towards one another. Via means producing a friction-locked connection, a clamped operative connection between the closure device and the grinding container is produced in a friction-locked manner 
         [0032]    For the closing of the ball mill, the grinding container is moved in the axial direction towards the closure device. After the first and second connecting devices have engaged into or through one another, the at least one adjustment element is rotated in the first direction of rotation and a friction-locked connection between the closure device and the grinding container is produced. For the opening of the ball mill, the friction-locked connection between the closure device and the grinding container is released and the adjustment element is rotated in a second counter-direction, opposite the first direction of rotation. The grinding container is then moved in the axial direction, more precisely away from the closure device. The first and second connecting devices disposed engaging into or through one another in an aligned manner are thus pulled apart and spaced apart from one another. 
         [0033]    The four largely quarter-circle-shaped adjustment elements are disposed on the outer edge of the grinding container flange and each cover, for example, an angle between 75° and 85°, in particular an angle of approx. 80°. An approx. 10° adjustment range is present in each case between the adjacent adjustment elements each covering approx. 80°. The purpose of this is to make the necessary free space available for the rotary adjustment of the adjustment elements. In the represented example of embodiment, the rotation of the adjustment element takes place for example through approx. 2° in each case. The required rotation can be varied and is dependent particularly on the spacing between the through-passage region and the support region of the second adjustment elements. 
         [0034]    The number of the first and second connecting devices can be adapted both in the first and in the second described embodiment. Particularly in the case of grinding containers and closing devices with a large diameter, for example with a diameter of several metres, the number is correspondingly increased in order to ensure a firm, reliable and sealing fastening. 
         [0035]    The closure system is a quick-action closure, by means of which the traversable grinding container can, quickly and easily and in particular without great manual effort, be flanged-mounted on and dismantled from a stationary closure device, in particular a stationary bearing pedestal, wherein an agitator, a corresponding drive and optionally further components are also assigned to the closure device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    Examples of embodiment are intended to explain the invention and its advantages in greater detail below with the aid of the appended figures. The size ratios of the individual elements with respect to one another in the figures do not always correspond to the actual size ratios, since some forms are represented simplified and other forms are represented enlarged in relation to the other elements for the sake of better illustration. 
           [0037]      FIG. 1  shows a diagrammatic transverse cross-section through a ball mill, 
           [0038]      FIG. 2  shows a diagrammatic longitudinal cross-section through an agitator ball mill. 
           [0039]      FIGS. 3 to 10  show different views and details of a first embodiment of a closure system according to the invention for a ball mill. 
           [0040]      FIGS. 11 to 17  show different views and details of a second embodiment of a closure system according to the invention for a ball mill. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0041]    Identical reference numbers are used for identical or identically acting elements of the invention. Furthermore, for the sake of clarity, only reference numbers that are required for the description of the given figure are represented in the individual figures. The represented embodiments only represent examples as to how the device according to the invention or the method according to the invention can be constituted and do not represent a conclusive limitation. 
         [0042]      FIG. 1  shows a diagrammatic cross-section through a ball mill  1 . Cylindrical grinding container  3  is mounted in a horizontally rotatable manner in a bearing frame  2 . Grinding stock  5  is filled into grinding container  3  by means of a grinding stock supply device  4 . Grinding stock supply device  4  is usually assigned to a first circular end wall (not represented). So-called grinding balls  6  or other suitable grinding aids are present in the interior of grinding container  3 . By rotation R of grinding container  3 , grinding stock  5  is ground down by grinding balls  6  and thus size-reduced. The output of size-reduced grinding stock  5  takes place by means of a grinding stock removal device  7  which, in the represented embodiment, is assigned to the second circular end wall lying opposite the first end wall. In particular, grinding balls  6  are held back at grinding stock removal device  7  and remain in grinding container  3 . 
         [0043]      FIG. 2  shows a diagrammatic longitudinal cross-section through an agitator ball mill  9 . The latter also comprises a horizontally mounted grinding container  3 . It can also be seen that a grinding stock removal device  7  with separation system  8  is assigned to a first end wall  10 . The other second end wall  11  of grinding container  3  is constituted open and comprises a grinding container flange  12 . Open end wall  11  of grinding container  3  is closed with a lid  13  with a lid flange  13 *. Sealing elements are disposed on lid  13  on the container side for the purpose of a sealing fastening. Furthermore, grinding stock supply device  4  is assigned to lid  13 , by means of which grinding stock supply device grinding stock  5  is introduced into grinding container  3 . Grinding container  3  is filled with grinding balls  6  and also comprises agitator elements  14 , which provide for the intensive movement of grinding balls  6 , while a grinding stock suspension  5 * for example is continuously pumped through the grinding chamber of grinding container  3 . Agitator elements  14  are disposed for example on a common drive shaft  15 , which is driven by a suitable drive means  16 . Drive means  16  is for example an electric motor  17  and is disposed on the outer side of lid  13 . 
         [0044]      FIGS. 3 to 10  show different views and details of a first embodiment of a closure system according to the invention for a ball mill.  FIG. 3  represents a detail of a horizontally mounted cylindrical grinding container  20 , in particular the region of open second end wall  21  with grinding container flange  22 , and  FIG. 5  shows a detail in respect thereof. A ring  23  with an outer toothing system is disposed on grinding container flange  22  on the lid side. Ring  23  is fastened for example to grinding container flange  22  by means of screw connections  26 . So-called outer-tooth gaps  25  are present between outer teeth  24 . The distance between the centre point of ring  23  and the point disposed closest to the latter in outer-tooth gaps  25  is preferably identical to the radius of grinding container flange  22 . This means that outer teeth  24  project beyond grinding container flange  22 . 
         [0045]    Outer teeth  24  have for example a largely cuboid shape. Average distance A 24  between two outer teeth  24  or average width B 25  of an outer-tooth gap  25  corresponds at least to width B 24  of an outer tooth  24 . Furthermore, wedge elements  27  are disposed on the container side of outer teeth  24 . When wedge elements  27  are viewed from the container side, their thickness increases normal to the plane of open end face  21  in each case in the clockwise direction. When open end face  21  is closed with lid  30 , these wedge elements  27  serve to produce a friction-locked connection between grinding container  20  and lid  30 , which will be explained in greater detail in connection with  FIGS. 7 to 10 . 
         [0046]      FIG. 4  shows a lid  30  for closing open second end wall  21  of grinding container  20  and  FIG. 6  shows a detail cross-section in respect thereof. Lid  30  comprises a lid flange  32 . Disposed above lid flange  32  is a large rotatable adjustment ring  33  with an inner toothing system comprising inwardly directed inner teeth  34 . In particular, inner teeth  34  are positioned in front of lid flange  32 , so that a free space  36  remains in each case between inner teeth  34  and lid flange  32 . 
         [0047]    Inner teeth  34  have for example a largely cuboid shape. Average distance A 34  between inner teeth  34  or average width B 35  of inner-tooth gap  35  corresponds at least to width B 34  of inner teeth  34 . In particular, width B 24  of outer teeth  24  roughly corresponds to width B 34  of inner teeth  34  and, in particular, average distance A 34  between two inner teeth  34  is at least slightly greater than width B 24  of outer teeth  24 . Furthermore, an average distance A 24  between two outer teeth  24  is at least slightly greater than width B 34  of inner teeth  34 . 
         [0048]    Furthermore, wedge elements  37  are disposed on the lid side of inner teeth  34 . When wedge elements  37  are viewed from the container side, their thickness increases normal to the plane of open end face  21  in each case anticlockwise. When open end face  21  of grinding container  20  is closed with lid  30 , these wedge elements  37  together with wedge elements  27  of outer teeth  24  of ring  23  disposed on grinding container flange  22  bring about the creation of a friction-locked connection, since they further increase the contact pressure. 
         [0049]    Two hydraulic cylinders  38  are disposed opposite one another on adjustment ring  33 , with the aid whereof adjustment ring  33  is rotated. Hydraulic cylinders  38  are fastened to a bearing substructure (not represented) of the ball mill or agitator ball mill. 
         [0050]    Grinding container  20  is mounted horizontally displaceable and for closure by lid  30  is moved towards the latter. Adjustment ring  33  must be in a working position AP according to  FIG. 7  here, so that outer teeth  24  of ring  23  disposed on grinding container flange  22  are pushed in an aligned manner into or through inner-tooth gaps  35  between inner teeth  35  of adjustment ring  33  of lid  30  (see also  FIG. 8 ). In particular, outer teeth  24  are moved so close to lid  30  that they largely abut against lid flange  32  or, as the case may be, against a sealing element or suchlike assigned to lid flange  32 . In first working position AP, first hydraulic cylinder  38 - 1  is extended and second hydraulic cylinder  38 - 2  lying opposite is retracted. Adjustment ring  33  is rotated as a result of simultaneous extension of second hydraulic cylinder  38 - 2  and retraction of first hydraulic cylinder  38 - 1 . Viewed from the container side, the adjustment ring rotates in the clockwise direction. As a result of the rotation of adjustment ring  33 , inner teeth  34  are preferably displaced completely in front of outer teeth  24 . This means that, in the locking position, outer teeth  24  are disposed completely in free space  36  between inner teeth  34  and lid flange  32 . An additional friction-locked connection is produced by wedge elements  27  of outer teeth  24 , said wedge elements widening in the clockwise direction, and wedge elements  37  of outer teeth  34 , said wedge elements widening in the anticlockwise direction, so that grinding container  20  is closed in a sealing manner with lid  30 . In particular, a force is produced in the direction of the longitudinal axis of the ball mill or grinding container  30  and therefore a firm connection between grinding container flange  22  and lid flange  32 . Adjustment ring  33  is supported on the lid flange  32 . 
         [0051]    Wedge elements  27  of outer teeth  24  are preferably made from a different material from wedge elements  37  of outer teeth  34 , in particular a material combination with as little adhesive friction as possible as selected. For example, wedge elements  37  of inner teeth  34  are made of steel and wedge elements  27  of outer teeth  24  of brass. Other suitable material combinations are however also conceivable. 
         [0052]      FIG. 9  shows a cross-section A-A through a grinding container  20  in the region of an inner tooth  34 , said grinding container having been moved up to lid  30 . 
         [0053]      FIG. 10  shows the arrangement according to  FIG. 7 , wherein adjustment ring  33  is in locking position VP, wherein first hydraulic cylinder  38 - 1  is retracted and opposite second hydraulic cylinder  38 - 2  is extended. Outer teeth  24  are disposed here in free spaces  26  between inner teeth  34  of adjustment ring  33  and lid flange  32  and the friction-locked sealing fastening of lid  30  to grinding container  20  is produced by wedge elements  37 ,  27  (not shown, see  FIGS. 6, 7 ). For the opening of lid  30 , adjustment ring  33  is rotated anticlockwise, wherein the first hydraulic cylinder  38 - 1  is extended and opposite second hydraulic cylinder  38 - 2  is retracted. The closure system thus arrives back into a working position AP according to  FIG. 7 , in which outer teeth  24  of ring  23  disposed on grinding container flange  22  are pushed in an aligned manner into or through inner-tooth gaps  35  between inner teeth  35  of adjustment ring  33  of lid  30 . Grinding container  20  can now be moved away from lid  30  by horizontal displacement. 
         [0054]    The closure system according to the represented first embodiment is suitable for the method according to the invention for opening and closing ball mills. In the closure system according to the represented first embodiment, inner-tooth gaps  35  are a component part of a rotatable adjustment ring  33  and represent the first connecting devices of the closure device, i.e. lid  30 . Outer teeth  24  assigned to grinding container flange  22  represent the second connecting devices on grinding container  20 . In first open working position AP of adjustment ring  33 , outer teeth  24  engage through inner-tooth gaps  35 . By rotation in the clockwise direction, adjustment ring  33  is transferred into closed locking position VP. Outer teeth  24  are thereby rotated with respect to inner-tooth gaps  35  in such a way that the outer teeth are now located in free space  36  between inner teeth  34  and lid flange  32 . Wedge elements  37 ,  27  as means producing a friction-locked connection are assigned both to inner teeth  34  and to outer teeth  24 , said wedge elements in locking position VP bringing about a clamped operative connection between lid  30  and grinding container  20  in a friction-locked manner. 
         [0055]    Furthermore, the arrangement of centring means  39  is indicated in  FIG. 7 . Lid flange  32  comprises for example two upper and two lower centring pins  39   a,    39   b,  which each point in the direction of grinding container  20 . If grinding container  20  is pushed against lid  30 , centring pins  39   a,    39   b  engage in corresponding bores of grinding container flange  22  and centring pins  39   a,    39   b  are guided in the latter. 
         [0056]      FIGS. 11 to 17  show different views and details of a second embodiment of a closure system according to the invention for a ball mill.  FIGS. 11 and 12  show a front view and a side view of a lid  50 . Lid  50  comprises a lid flange  51 , to which a plurality of first connecting devices  52  is assigned. First connecting devices  52  are constituted in particular as bolts  53  with a mushroom-like widened end region  54 . Widened end region  54  of first connecting devices  52  is constituted in each case on the side of lid  50  facing grinding container  60 . The other end of respective bolt  53  is connected in each case to a hydraulic cylinder  55 , by means of which bolt  53  can be displaced parallel to the longitudinal axis of grinding container  60 . 
         [0057]      FIG. 13  shows a plan view of grinding container flange  62  of a grinding container  60  as viewed from the container side. Four adjustment segments  63  are disposed at the so-called rear side of grinding container flange  62 . Each adjustment segment  63  comprises six second connecting devices  65 , which are correspondingly a component part of respective adjustment segment  63 . Second connecting devices  65  each comprise slotted holes, which connect a through-passage region  66  to a support region  67  for widened end region  54  of first connecting devices  52 . Bolt rod  53  of first connecting device  52  itself always stands free in the slotted hole, through-passage region  66  and support region  67 . In alignment with through-passage regions  66  of second connecting devices  65  on adjustment element  63 , grinding container flange  62  comprises corresponding through-passage openings (not represented) for first connecting devices  52 . 
         [0058]      FIG. 11  is represented reduced in size compared to  FIGS. 12 and 13 . The diameters of grinding container flange  62  and lid flange  51  are at least largely identical. 
         [0059]      FIG. 14  shows a grinding container  60  moved up to lid  50 , wherein adjustment segments  63  are in working position AP, and  FIG. 15  shows a grinding container  60  moved up to lid  50 , wherein adjustment segments  63  are in locking position VP.  FIGS. 16 and 17  each show detail views in respect thereof, particularly the region in which adjustment segments  63 - 1  and  63 - 4  are largely adjacent to one another. 
         [0060]    In open working position AP of adjustment segments  63 , first fastening devices  52  engage through the through-passage openings (not represented) of grinding container flange  62  and respective through-passage regions  66  of second connecting devices  65  on adjustment segments  63 . Bolts  53  are adjusted by means of hydraulic cylinders  55  especially in such a way that mushroom-like widened end regions  54  on the side facing grinding container  60  project beyond adjustment segments  63 , after grinding container  60  has been moved as close as possible to lid  50  for the closure. This can be seen particularly well in  FIG. 16 . 
         [0061]    Two hydraulic cylinders  64 ,  64 - 1   a  and  64 - 1   b  etc., are assigned in each case to the four adjustment segments  63 - 1  to  63 - 4 , said hydraulic cylinders bringing about a targeted rotation of adjustment segments  63 . By lengthening hydraulic cylinder  64 - 1   b  and shortening hydraulic cylinder  64 - 1   a,  adjustment segment  63 - 1  is transferred anticlockwise into locking position VP. By lengthening hydraulic cylinder  64 - 2   b  and shortening hydraulic cylinder  64 - 2   a,  adjustment segment  63 - 2  is transferred by a rotation in the clockwise direction into locking position VP. By lengthening hydraulic cylinder  64 - 3   b  and shortening hydraulic cylinder  64 - 3   a,  adjustment segment  63 - 3  is transferred anticlockwise into locking position VP, and by lengthening hydraulic cylinder  64 - 4   b  and shortening hydraulic cylinder  64 - 4   a,  adjustment segment  63 - 4  is transferred by a rotation in the clockwise direction into locking position VP. The adjustment of the four adjustment segments  63 - 1  to  63 - 4  by means of hydraulic cylinders  64  is preferably controlled jointly and takes place largely synchronously. This means that the four largely quarter-circle-shaped adjustment segments are each transferred into their closed locking position by rotation in the clockwise or anticlockwise direction. In the represented example of embodiment, two of adjustment segments  63 - 2  and  63 - 4  rotate in the clockwise direction and the other two adjustment segments  63 - 1  and  63 - 3  rotate in the anticlockwise direction when the adjustment segments are transferred from the working position into the locking position. Alternatively, it would be conceivable for hydraulic cylinders  64  to be disposed in such a way that all adjustment segments  63  rotate in a common direction of rotation. It is important here that mushroom-like widened end regions  54  of first connecting devices  52  project freely beyond adjustment segments  63  during the rotation of adjustment segments  63 . 
         [0062]    The rotation of adjustment segments  63 - 1  to  63 - 4  is also guided by guide screws  71  guided in slotted holes  70 . 
         [0063]    In closed locking position VP, first connecting devices  52  and second connecting devices  65  are rotated towards one another. In particular, second connecting devices  65  have been rotated with respect to first connecting devices  52  in such a way that mushroom-like widened end regions  54  of first connecting devices  52  are now disposed directly on support regions  67  of second connecting devices  65 . 
         [0064]    First connecting devices  52  are withdrawn by means of hydraulic cylinders  55  assigned to first connecting devices  52 . This movement is limited by widened end regions  54  of first connecting devices  52  and support regions  67  of second connecting devices  65 . In particular, a friction-locked connection is produced between mushroom-like widened end regions  54  of first connecting devices  52  and support regions  67  of second connecting devices  65 . This means that hydraulic cylinders  55  form the means producing the friction-locked connection, by means of which an operative connection between lid  50 , in particular lid flange  51 , and grinding container  60 , in particular grinding container flange  62 , is constituted in a friction-locked manner. 
         [0065]    Furthermore, the arrangement of centring means is also indicated in  FIGS. 11 and 13 . Lid flange  51  comprises two centring pins  59  pointing in the direction of grinding container  60 . Said centring pins engage in corresponding bores (not represented) of grinding container flange  62  and are guided in the latter. Adjustment segments  63 - 2  and  63 - 3  comprise slotted holes  69  aligned with the bores in grinding container flange  62 . Slotted holes  69  are necessary in order that a rotation of adjustment segments  63 - 2  and  63 - 3  is possible despite centring.  FIG. 13  shows the arrangement of centring pins  59  of lid flange  51  in slotted holes  69  of adjustment segments  63 - 2  and  63 - 3 .  FIG. 13  shows adjustment segments  63  in working position AP and illustrates the fact that centring pins  59  do not prevent the rotation of adjustment segments  63  from occupying locking position VP (see  FIGS. 15 and 17 ). In particular, slotted hole  69   a  enables a rotation of adjustment segment  63 - 2  in the clockwise direction and slotted hole  69   b  enables a rotation of adjustment segment  63 - 3  in the anticlockwise direction. 
         [0066]    The invention has been described by reference to a preferred embodiment. A person skilled in the art can however imagine that modifications or changes to the invention can be made without thereby departing from the scope of protection of the following claims.