EP0700724B1 - Method and apparatus for continously autogenously milling a flowable processing material - Google Patents

Description

The invention relates to a method for continuously autogenous grinding of a flowable, insoluble particle containing different diameters Treated goods according to the preamble of claim 1, and a device for performing the method according to the preamble of claim 8.

The grinding of particularly hard materials such as silicates and carbides is complex. It has become known through use in practice use agitator mills, each with a cylindrical container have in the concentric a high-speed driven agitator is arranged. The grinding container is at least essentially with Auxiliary grinding bodies filled. The material to be treated is in a flowable form, for example, slurried with water, the container on one End fed and leaves the container at the other end. The mixture the material to be treated and auxiliary grinding media are turned into an intensive movement is shifted so that an intensive grinding takes place. In the area of the regrind outlet, a grinder auxiliary device must be used be provided, by means of which the auxiliary grinding bodies can be separated from the material to be treated, so that the latter is free of auxiliary grinding media can leak. Wear is when grinding extremely hard particles the grinding aid body large. If on the other hand low-quality regrind are ground as mass products, then - even if the auxiliary grinding body wear is not too big - the cost of grinding auxiliary body wear not portable compared to the value of the regrind. About that In addition, there is a very great risk that the grinding aid retainer through regrind particles that are still too large and / or worn Grinding auxiliary body is added, which at least leads to malfunctions or can also lead to partial destruction of the agitator mill. This There is a particular danger if the throughput is high Treated goods, i.e. correspondingly high flow rates of the material to be treated is worked in the agitator mill.

EP 0 247 859 A and EP 0 376 403 A each have a device and a process for autogenous milling of hard solids the preambles of claims 1 and 8 known. Is used an agitator mill with a wall and a floor Grinding bowl. At the top of the grinding chamber wall is a cylindrical one Sieve provided as a retention device. The material to be treated is fed to the grinding chamber from below through the floor and from above through the sieve enveloping the grinding chamber is removed. Be through this sieve Large particles are retained while material to be treated is ground with powder Particles can escape. There is a significant risk of Clogging of the sieve and considerable sieve wear. Furthermore hardly take the larger diameter particles sitting in front of the sieve still participating in the autogenous grinding process.

DE 34 31 636 C2 (corresponding to EP 0 219 740 B1) is an annular gap ball mill for continuous fine grinding, especially of mineral ones Hard materials, known with a closed grinding container, in which a rotor is arranged, the outer surface with the inner surface of the Grinding container limited a grinding gap. So-called are in the grinding gap Grinding beads, i.e. Grinding aid body, arranged. The top and bottom of the rotor taper in opposite directions. Because of the double conical design of the grinding gap becomes one Discharge of the auxiliary grinding bodies with the material to be treated through an outlet opening and thus a reduction in the amount of auxiliary grinding media or Prevents grinding effect. This is due to the fact that a given Grinding auxiliary excess in the radial annular chamber at the top of the grinding gap, i.e. in the area of the largest rotor diameter, collects, and forms a floating barrier there, which retains the active grinding aids in the grinding gap without after Type of a sieve or the like the outlet of the finely ground material to be treated hinder from the grinding gap towards the outlet opening. A subsequent separation of auxiliary grinding bodies and material to be treated is therefore not applicable. However, this only applies to low throughputs, i.e. at low flow rate of the ground material to be treated in the grinding gap. With larger throughputs and accordingly higher flow velocities of the material to be treated in the grinding gap the auxiliary grinding bodies are also carried out, so that here also a subsequent separation of auxiliary grinding bodies and material to be treated is necessary is. The above-mentioned problems of grinding media wear also exist.

The invention has for its object a method and an apparatus to create a continuous autogenous grinding of material to be treated in a particularly simple manner enable even at high throughputs without malfunctions.

This task is carried out in a method of the type specified at the outset solved by the features of claim 1. She will continue to work for one Device of the type mentioned by the features of the claim 8 solved. The essence of the invention is that the particles with concentrated larger diameter in the grinding chamber and there on the one hand as it were as auxiliary grinding bodies for grinding the particles of smaller diameter used and on the other hand itself on the outside be rubbed off. So there are no independent alien grinding aids used; furthermore there is no auxiliary grinding device retention device necessary because they are used as auxiliary grinding bodies Particles remain in the grinding chamber. Malfunctions due to clogging a grinding aid restraint device can no longer occur. The material to be treated is classified into larger particles Diameter, which are used for grinding and in smaller particles Diameter to be ground. The particles bigger Diameters are entered into the grinding chamber of the agitator mill and stay there. Then only the pre-classified material to be treated is used for grinding with particles of smaller diameter through the grinding chamber guided.

Numerous, partly inventive, configurations result from the Subclaims.

Fig. 1

eine erste nach Art einer Rührwerksmühle aufgebaute Ausführungsform einer Vorrichtung zum autogenen Mahlen im Vertikalschnitt in schematischer Darstellung,

Fig. 2

eine zweite nach Art einer Rührwerksmühle aufgebaute Ausführungsform einer Vorrichtung zum autogenen Mahlen im Vertikalschnitt in schematischer Darstellung,

Fig. 3

eine dritte nach Art einer Rührwerksmühle aufgebaute Ausführungsform einer Vorrichtung zum autogenen Mahlen im Vertikalschnitt in schematischer Darstellung,

Fig. 4

eine vierte nach Art einer Rührwerksmühle aufgebaute Ausführungsform einer Vorrichtung zum autogenen Mahlen im Vertikalschnitt in schematischer Darstellung,

Fig. 5

eine fünfte nach Art eines Ringmischers aufgebaute Ausführungsform einer Vorrichtung zum autogenen Mahlen im Vertikalschnitt in schematischer Darstellung,

Fig. 6

eine sechste nach Art einer Rührwerksmühle aufgebaute Ausführungsform einer Vorrichtung zum autogenen Mahlen im Vertikalschnitt in schematischer Darstellung und

Fig. 7

ein Regelungs-Blockschaltbild für eine Rührwerksmühle.

Further features, advantages and details of the invention result from the following description of five exemplary embodiments with reference to the drawing. It shows

Fig. 1

1 shows a first embodiment of a device for autogenous grinding, constructed in the manner of an agitator mill, in vertical section in a schematic illustration,

Fig. 2

2 shows a second embodiment of a device for autogenous grinding, constructed in the manner of an agitator mill, in a vertical section in a schematic illustration,

Fig. 3

3 shows a third embodiment of a device for autogenous grinding, constructed in the manner of an agitator mill, in vertical section in a schematic illustration,

Fig. 4

4 shows a fourth embodiment of a device for autogenous grinding, constructed in the manner of an agitator mill, in vertical section in a schematic illustration,

Fig. 5

5 shows a fifth embodiment of a device for autogenous grinding, constructed in the manner of a ring mixer, in vertical section in a schematic illustration,

Fig. 6

a sixth embodiment of a device for autogenous grinding in vertical section in a schematic representation and constructed in the manner of an agitator mill

Fig. 7

a control block diagram for an agitator mill.

The embodiments according to FIGS. 1 to 3 are in the Principle of so-called horizontal agitator mills. These usually show Have a stand 1, which is supported on the floor 2. On the front 3 of the stand 1, a support arm 4 is attached.

A drive motor 5, which can be speed-controlled, is accommodated in the stand, which is provided with a V-belt pulley 6, from the V-belt 7 and a further V-belt pulley 8 a drive shaft 9 is driven by rotation. The drive shaft 9 is in the stand 1 by means of several Bearing 10 rotatably mounted.

On the support arm 4 is in a corresponding receptacles 11 essentially cylindrical grinding bowl 12 supported. The grinding container 12 has a cylindrical wall 13 and is on one, the stand 1 facing End by means of a cover 14 and at the opposite end closed by a bottom 15. It encloses a grinding room 16.

Concentric to the common central longitudinal axis 17 of the grinding container 12 and drive shaft 9, an agitator shaft 18 is arranged in grinding chamber 16, which penetrates the lid 14. The grinding chamber 16 is by means of seals 19 sealed between the cover 14 and the shaft 18. The wave 18 is overhung, that is, no longer supported in the area of the floor 15. It is provided with stirring tools 20 along its length in the grinding chamber 16, which in the present case are stirring disks 21. These stirring disks 21 can - as shown on the right in FIG. 1 - additionally with extending parallel to the axis 17, in the form of a Cage arranged stirring bars 22 are provided, by means of which the centrifugal forces increase.

On the grinding container 12 there is an inlet connection 23 adjacent to the cover 14 attached through which the material to be treated is fed. At the bottom lying side of the wall 13 of the grinding container 12 is one over a essential part of the length of the grinding container 12 between the recordings 11 extending emptying flap 24 attached.

In all embodiments, the grinding bowl 12 is with an outlet provided that different in the different embodiments is designed. Common to all outlets is that a grinding aid retaining device, as is generally the case with agitator mills, is not provided. With such auxiliary grinder retainers it is either sieves in various designs or so-called separating gap separating devices, such as those described in DE-PS 14 82 391 (corresponds to GB-PS 1 056 257) are described.

1 is in the bottom 15 coaxial to the axis 17 an outlet pipe 25 is arranged, the front with an opening 26th is provided. This outlet pipe 25 extends into the vicinity of the agitator shaft 18, i.e. up to the vicinity of the end stirring disc 21. An this end-side stirring disk 21 is, for example, a truncated cone, attached to the bottom 15 open short tube section 27, which leaves a passage 28 to the floor 15 free. The outlet pipe 25 and the pipe section 27 overlap one another in the direction of the axis 17.

In the embodiment according to FIG. 2, the agitator shaft 18 is adjacent to its free end, between the last two stirring disks 21, provided with outlet openings 29 which lead into a drain channel 30 open into the hollow agitator shaft 18. The drain channel 30 opens in the region of the end of the outside of the grinding container 12 Agitator shaft 18 from this. To enhance the centrifugal effect can be the mentioned stirring bars 22 in the region of the opening 29.

In the embodiment according to FIG. 3, the agitator shaft 18 is in the area of their free end and also there between the last two each other adjacent stirring disks 21 are provided with outlet openings 31, the in an outlet channel open to the free end of the agitator shaft 18 32 flow into. This in turn opens into an arranged in the floor 15 Outlet pipe 33, which has its end face opposite the free end the agitator shaft 18 leaves only the smallest possible gap.

The embodiment of Fig. 4 is by a vertical agitator mill educated. As far as the parts are identical, the same reference numbers as used in FIGS. 1 to 3, as far as individual parts only constructively different, but functionally the same, they will same reference numerals as in the embodiments of FIGS. 1 to 3 used, but with a raised line. The inlet connection 23 is provided in the region of the bottom 15 'below, which is provided with an emptying flap 24 '. The outlet is housed in the lid 14 ', where none compared to the agitator shaft 18 Seal is necessary or provided. The outlet is through a Agitator shaft 18 surrounding outlet port 34 formed between the and an annular outlet channel 35 is limited to the shaft 18. This opens into an outlet cup 36 located above the lid 14 ' which in turn opens a discharge line 37.

The stirring disk 21 adjacent to the cover 14 'is only released a very narrow outlet gap 38 to the lid 14 'so that high centrifugal forces are generated in the outlet gap 38.

During the embodiments according to FIGS. 1 to 4 agitator mills are, the embodiment of FIG. 5 is in the manner of a high-speed drivable Mixer built. With the embodiments according to Fig. 1 to 3 functionally similar parts are given the same reference numerals provided, but with a double prime added becomes. To this extent, no further description is given.

The agitator shaft 18 "is on the one hand in a bearing 10" in the area of Lid 14 "and on the other hand in a bearing 10" in the area of the floor 15 ", i.e. it is not flying, but is mounted on both ends Passage of the agitator shaft 18 "through the cover 14" on the one hand and the bottom 15 "on the other hand seals 19" are provided. The agitator shaft 18 "is provided with stirring tools 20, which are can also act again stirring discs 21; the stirring tools 20 can also be designed as classic shovel-like mixing tools 39 be, as is also shown in Fig. 5.

An inlet connection 23 is provided adjacent to the cover 14 ″ the grinding chamber 16 "opens out.

Adjacent to the floor 15 ", also there between the last two Stirring discs 21 are in the agitator shaft 18 "outlet openings 31 "formed in a drain channel formed in the agitator mill 32 ", which in turn is behind the cover-side bearing 10" exit. Of course, the stirring bars described can also be used here 22 are provided.

Only in Fig. 5 is indicated that the material to be treated is the treatment process is fed several times. For this purpose, a storage container 40 is provided, which is connected to the inlet connection 23 via a feed line 41 is. In this feed line 41 is driven by a motor 42 Pump 43 switched, by means of which the material to be treated is transported. The drain channel 32 ″ is in turn connected via a return line 44 connected to the reservoir 40.

In the embodiment according to FIG. 6, the grinding container 12 '' has its length between the lid 14 "'and the bottom 15"' distributes several Inlet nozzle 23 "'on by means of a common supply line 41 are supplied. From the bottom 15 "'opens an outlet pipe 25 "', which runs concentrically to the central longitudinal axis 17. Die Drive shaft 9 is provided with a pot-shaped agitator that consists of a rotor disk 45 attached to the drive shaft 9 is formed, on the parallel and concentric to the central longitudinal axis 17, extending essentially over the length of the grinding container 12 "' Rods 46 are attached to their adjacent to the floor 15 "' Connected ends for stiffening with a connecting ring 47 could be. The rotor disk 45 with the bars 46 therefore forms a type Cage. On the bars 46 are 20 blades serving as stirring tools or paddle 48 attached, which is close to the wall 13 "'of Extend grinding container 12 "'. The stirring tools 20 therefore sweep over only the radially outer area of the grinding chamber 16 "'. Otherwise 6 are the same reference numerals as in the previous figures have been used insofar as parts are identical. As far as parts functional identical, but slightly different in construction, they are the same Reference number but with a triple prime.

The described continuously operating devices are used, among other things, for grinding particularly hard items to be treated; these are, for example, silicates and carbides. However, they are also used to grind low-value bulk goods, such as calcium carbonate, sand (SiO ₂ ), mineral substances and in particular ores. The material to be treated is brought into flowable form in water or another suitable liquid and is fed to the grinding container 12 or 12 'or 12 "or 12"' through the inlet connection 23 or the inlet connection 23 "'and through the high-speed rotating stirring tools 20 At the beginning of a grinding process, particles of larger diameter are entered into the respective grinding chamber 16, 16 "or 16"'. Two case groups can be distinguished If the coarse particles are partially rubbed off, they have to be refilled in. In the other case group, coarse particles and fine particles are entered from the beginning, whereby the coarse particles are concentrated in the grinding chamber.

The coarse particles, i.e. the particles of larger diameter, have one Size from 0.1 to 5.0 and usually from 1.0 to 2.0 mm. The lower one The limit of their diameter is 0.1 to 0.3 mm, the usual upper limit at 3.0 to 4.0 mm. The fine particles, i.e. the particles smaller The diameter of the material to be treated should be by a factor of 0.3 to 0.05 smaller than the particles used as auxiliary grinding bodies larger diameter. The grinding container 12 or 12 'or 12 "or 12 "'are completely filled with the items to be treated. Those in the items to be treated Particles of larger diameter contained are reinforced in the outside area, i.e. towards the wall 13 or 13 "of the grinding container 12, 12 ', 12 "or 12"' flung, so they are in the grinding room 16, 16 "concentrated. Take the larger diameter particles take part in the grinding process, that is to say they grind as auxiliary grinding bodies the smaller particles, whereby they themselves are also rubbed off until the desired particle size distribution is reached. Because the material to be treated in the area of the axis 17 or the shaft 18 or 18 "by the outlets 25, 29, 31, 31 ", 34, 25" 'out of the grinding chamber 16, 16 ", 16" 'emerges, these larger particles remain at least predominantly in the grinding chamber 16, 16 ", 16" '. If the material to be treated is used several times is guided through the grinding chamber 16 or 16 "or 16" ', then on Finally, the larger particles were at least partially crushed. So far Particles of larger diameter are discharged with the treated regrind they can not clog a restraint, because a such does not exist. All outlets have a minimum width a that is significantly larger than the larger diameter particles. The minimum width of an outlet is at least 5 mm, usually min at least 10 mm.

If in the case of a circular grinding, the one located in the storage container 40 Treated goods are ground to a specified particle size distribution then the batch located in the storage container 40 can be exchanged be, which are in the grinding chamber 16 or 16 "or 16" ' Amount of material to be treated is not exchanged as it is in this a higher proportion of particles of larger diameter is contained. These measures for the multiple passage of material to be treated by the Grinding room 16 or 16 "or 16" 'can be used in the same way for all other embodiments can be applied.

So that a strong concentration of particles of larger diameter in Grinding chamber takes place, the agitator speed on the one hand and the Throughput of the material to be treated on the other hand optimally adapted to one another become. The power consumption of the drive motor can be used as a key figure for this 5 or 5 "or its current consumption. Basics The aim of regulation is to achieve maximum power consumption. This is achieved through a high concentration of particles large diameter in the grinding chamber. If with an increase in Throughput the power consumption decreases, it can be concluded from this that the proportion of particles of larger diameter in the grinding chamber 16 or 16 "or 16" 'has decreased either by abrasion or but by discharge. In this case, particles must be of larger diameter existing treatment items are added. If this is the case Power consumption increases again, the problem is solved. If this If this is not the case, particles with larger diameters become recognizable carried out; in this case either the throughput of material to be treated be reduced, or in the presence of a variable speed Drive motor 5 increases the speed of the agitator shaft 18, 18 " become.

Specifically, the regulation can be carried out in the manner shown in FIG. 7 become. With the drive shaft 9 and thus with the agitator shaft 18 is connected to a speed detection unit 49 which is a speed corresponding signal to a regulating and control device 50. It the power consumption of the drive motor 5 continues to be by means of a Power detection device 51 added and to the regulating and control device 50 given. It is also the pump 43 a throughput detector assigned which is a throughput per unit time outputs the corresponding signal to the control device 50. In the Throughput detection device 52 can be a speed measuring device act, since pumps operating with no slip or with constant slip the speed is a measure of the throughput. Furthermore, the drive motor 5 assigned a speed adjustment device 53, in which it can be, for example, a frequency converter. In the same The drive motor 42 of the pump 43 is a speed adjustment device 54 assigned, which is also a frequency converter can act. The speed of the drive shaft 9, the power consumption of the drive motor 5 and the flow rate of the pump 43 are used as inputs 55, 56, 57 entered in the regulating and control device 50. Farther a setpoint for the power consumption via an input 58 in the regulation and control device 50 entered. From the regulating and control device 50 is according to the control scheme given above The speed adjustment device 53 of the drive motor via outputs 59, 60 5 and the speed adjustment device of the motor 41 of the pump 43 controlled. In the first case, the speed of the agitator is changed; in the in the second case, the throughput of the pump 43 is changed.

Claims (24)

1. A method for the continuous autogenous grinding of free-flowing stock containing insoluble particles of varying diameter,
   wherein the stock is supplied to a grinding chamber (16, 16', 16"') located in a grinding receptacle (12, 12', 12", 12"') which has a wall (13, 13', 13", 13"') and a bottom (15, 15', 15", 15"'), where it is set rotating concentrically of an axis (17), and wherein insoluble particles of greater diameter are concentrated in the grinding chamber (16, 16", 16"') superproportionally as compared to particles of smaller diameter,
   characterized
   in that - at an end of the grinding chamber (16, 16', 16"') closed by a lid (14, 14', 14", 14"') - the stock is discharged from the grinding chamber (16, 16', 16"') through an outlet aperture in the vicinity of the axis (17), the minimum width a of the outlet aperture being substantially greater than the particles of greater diameter.
2. A method according to claim 1, characterized in that the particles of smaller diameter are smaller than the particles of greater diameter by the factor 0.3 to 0.05.
3. A method according to claim 1 or 2, characterized in that predominantly particles of greater diameter are supplied to the grinding chamber (16, 16", 16"') at the beginning of a grinding operation, particles of smaller diameter being predominantly supplied during the ensuing grinding operation.
4. A method according to one of claims 1 to 3, characterized in that - referred to the axis (17) - stock is supplied to one end of the grinding chamber (16, 16"') and is discharged from the grinding chamber (16, W') at the other end.
5. A method according to one of claims 1 to 3, characterized in that - referred to the axis (17) - stock is supplied along the length of the grinding chamber (16"').
6. A method according to one of claims 1 to 5, characterized in that the stock is repeatedly run through the grinding chamber (16, 16"').
7. A method according to one of claims 1 to 6, characterized in that for the discharge of inorganic particles of higher density and/or greater diameter from the grinding chamber (16, 16", 16"'), the supply of stock to the grinding chamber (16, 16", 16"') is reduced and/or the rotation is increased.
8. An apparatus for putting into practice the method according to one of claims 1 to 7, comprising

   a grinding receptacle (12, 12', 12", 12"') enclosing a grinding chamber (16, 16", 16"'), which is free from auxiliary grinding bodies, by means of a wall (13, 13', 13", 13"') and a bottom (15, 15', 15", 15"');

   an agitator unit rotatably disposed in the grinding receptacle (12, 12', 12", 12"') concentrically of the axis (17) thereof;

   agitator elements (20) attached to the agitator unit; a drive motor (5, 5') coupled with the agitator unit;

   at least one stock supply connector (23, 23"') opening into the grinding chamber (16, 16", 16"'); and

   at least one outlet (25, 25"'; 29; 31, 31"; 34) for treated stock

   characterized

   in that the grinding chamber (16, 16", 16"') is closed by a lid (14, 14', 14", 14"'); and

   in that the at least one outlet (25, 25"'; 29; 31, 31"; 34) is disposed in the vicinity of the axis (17) and does not comprise an auxiliary grinding body retaining device.
9. An apparatus according to claim 8, characterized in that the outlet is an outlet pipe (25), which is disposed concentrically of a cantilevered agitator shaft (18) and which is open frontally thereto.
10. An apparatus according to claim 9, characterized in that in the direction of the axis (17), the outlet pipe (25) is at least partially covered by a pipe section (27) connected with the agitator shaft (18).
11. An apparatus according to claim 9 or 10, characterized in that a passage (28) is formed between the pipe section (27) and an adjacent bottom (15) of the grinding receptacle (12) and/or between the outlet pipe (25) and the agitator shaft (18).
12. An apparatus according to one of claims 8 to 11, characterized in that the outlet is formed by at least one outlet aperture (29, 31, 31") provided in an agitator shaft (18, 18") and opening into a discharge conduit (30, 32, 32") located in the agitator shaft (18, 18").
13. An apparatus according to one of claims 8 to 12, characterized in that the outlet is an annular outlet passage (35) encircling an agitator shaft (18).
14. An apparatus according to claim 13, characterized in that the outlet passage (35) is defined by an outlet connector (34), which is provided in a lid (14') of the grinding receptacle (12') and forms a passage for the agitator shaft (18).
15. An apparatus according to one of claims 8 to 14, characterized in that at least one agitator element (20) is provided in direct vicinity to an outlet (25; 29; 31, 31"; 34).
16. An apparatus according to claims 12 and 15, characterized in that - referred to the axis (17) - at least one agitator element (20) is mounted on the agitator shaft (18, 18") on either side of the at least one outlet aperture (29, 31, 31").
17. An apparatus according to one of claims 8 to 16, characterized in that the agitator elements (20) are agitator disks (21).
18. An apparatus according to one of claims 8 to 17, in particular according to claim 16, characterized in that agitator rods (22) disposed in the way of a cage approximately parallel to the axis (17) are provided on the agitator elements (20).
19. An apparatus according to one of claims 8 to 18, in particular according to one of claims 8 to 11 and 14 to 17, characterized in that the grinding receptacle (12, 12", 12"') is approximately horizontal.
20. An apparatus according to one of claims 8 to 18, in particular according to one of claims 8 and 12 to 17, characterized in that the grinding receptacle (12') is substantially vertical and wherein the supply connector (23) opens into the lower portion of the grinding receptacle (12') and wherein the outlet (35) is provided in the upper portion of the grinding receptacle (12').
21. An apparatus according to claim 8, characterized in that the agitator unit is provided with rods (46) in the way of a cup-shaped cage, which extend parallel and concentrically of the axis (17) and to which agitator elements (20) are attached in the way of blades or paddles (48), respectively.
22. An apparatus according to claim 8, characterized in that several supply connectors (23"') open into the grinding chamber (16"'), which are disposed on the wall (13"') of the grinding receptacle (12") in a manner distributed along the wall (13"') thereof.
23. An apparatus according to claim 8, characterized in that the at least one outlet (25, 25"'; 29; 31, 31"; 34) for treated stock has a minimum width (a) of at least 5 mm and preferably at least 10 mm.
24. An apparatus according to one of claims 8 to 23, characterized in that a control unit (50) is provided for the increase of the speed of the agitator unit and/or for the reduction of the supply of stock upon decrease of the power draw of the drive motor (5, 5").

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