US3612415A

US3612415A - Beater mill for separating nongrindable and grindable materials

Info

Publication number: US3612415A
Application number: US801534A
Authority: US
Inventors: Herbert Alfred Merges
Original assignee: ULTREX CHEMIC GmbH
Current assignee: ULTREX CHEMIC GmbH
Priority date: 1968-02-27
Filing date: 1969-02-24
Publication date: 1971-10-12
Anticipated expiration: 1988-10-12
Also published as: GB1260953A; AT297457B; FR1600181A; CH489278A

Abstract

A beater mill for grinding grindable materials and separating nongrindable materials from a mixture comprises a fill chute, a rotor carrying rotating beaters partially surrounded by a sieve, and a discharge chute into which nongrindable materials are driven by the beaters. The discharge chute axis extends tangentially from the rotor for receiving the nongrindable materials. The fill chute has a bottom surface which is connected to the rotor housing at a point which is below the greatest height of the rotor diameter so that the mixture to be ground is struck by the beaters as it flows into the rotor region. The discharge chute is arranged at an angle to the fill chute and has an axis which intersects the fill chute axis within that quadrant of the rotor that faces the fill chute. Accordingly, materials falling back towards the rotor from the discharge chute are more likely to be again driven into the discharge chute and less likely to become jammed between the rotor and the sieve.

Description

United States Patent 1,683,304 9/1928 Roebke 241/82 X 3,378,956 4/1968 Parks et al. 49/485 3,442,458 5/1969 Meyer 241/82 Primary Examiner-Robert C. Riordon Assistant Examiner-Gary L. Smith Att0rneySpencer & Kaye ABSTRACT: A beater mill for grinding grindable materials and separating nongrindable materials from a mixture comprises a fill chute, a rotor carrying rotating beaters partially surrounded by a sieve, and a discharge chute into which nongrindable materials are driven by the beaters. The discharge chute axis extends tangentially from the rotor for receiving the nongrindable materials. The fill chute has a bottom surface which is connected to the rotor housing at a point which is below the greatest height of the rotor diameter so that the mixture to be ground is struck by the heaters as it flows into the rotor region. The discharge chute is arranged at an angle to the till chute and has an axis which intersects the fill chute axis within that quadrant of the rotor that faces the fill chute. Accordingly, materials falling back towards the rotor from the discharge chute are more likely to be again driven into the discharge chute and less likely to become jammed between the rotor and the sieve.

[72] Inventor Herbert Alfred Merges Wolfgang, near l-lanau, Germany [21] Appl. No. 801,534 [22] Filed Feb. 24, 1969 [45] Patented Oct. 12, 1971 [73] Assignee Ultrex-Chemie G.m.b.H.

- Wolfgang bei Hanan, Germany [32] Priority Feb. 27, 1968, Oct. 12, 1968 [33] Germany [31] P16 07 608.7 and P 18 02 819.8

[54] BEATER MILL FOR SEPARATING NONGRINDABLE AND GRINDABLE MATERIALS 14 Claims, 8 Drawing Figs.

[52] US. Cl. 241/73, 241/82, 241/189 R, 241/275, 241/285 [51] Int. Cl B02c 13/00, B02c 13/284, B02c 19/12 [50] Field of Search 241/73, 82, 188, 189 R; 49/485 [56] References Cited UNITED STATES PATENTS 1,278,542 9/1918 Williams 241/82 75 Z O O 4 /0 PATENTED 0m 1 2 I971 3,612, 11 5 SHEET 2 OF 3 Fig.3

mvsrvron Herbert Alfred Merges ATTORNEYS Pmminnmm 3.612 415 SHEET 30F 3 v INVENTOR Herbert Alfred Merges ATTORNEYS BEA'IER MILL FOR SEPARATING NONGRINDAIMLE AND GRINDABLE MATERIALS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a grinding mill, and more particularly to such a mill in which grindable materials in a mixture are ground and nongrindable materials are driven away through a discharge chute.

2. Description of the Prior Art Beater mills are known which include a fill chute, a mill including a rotor carrying rotating heaters, a sieve of semicircular cross section which surrounds the bottom of the rotor, and a discharge chute for nongrindable materials at the top of the rotor. Some known mills have the discharge chute arranged at an angle to fill chute and have the axis of the discharge chute so arranged that it is tangential to the rotor in that quadrant of the rotor into which it moves as the beaters ascend from the sieve. In such mills the discharge chute axis intersects the axis of the fill chute outside of the periphery of the beaters.

Beater mills of the described type are known and are used in the broadest sense for inhomogeneous materials, for example for hard coal, residential and industrial refuse, feeds or the like. One such mill (German Pat. No. 1,164,2l4a consists of a hammer mill rotor disposed in a substantially closed housing, the housing being provided with a vertical fill shaft and a likewise vertical discharge shaft for separated material disposed at a distance from each other over the upper ascending and descending quadrants of the heaters. This device is not suited for uses in which it would be unacceptable to permit those refuse components which cannot be comminuted, e.g. tin cans or the like, to fall onto the screen or grate disposed in the bottom portion of the mill housing. The same applies to the beater mill according to German Pat. No. 488,715 in which the connecting pipes for the feeding and discharging streams, i.e. for blown air and for the ground materials or for both together, are disposed at the outer mill periphery in the rotational plane of the heaters, the introduction of the streams occurring in a direction counter to the direction of rotation of the heaters, particularly since in this mill embodiment a separation of the inhomogeneous grinding components is not possible.

Another known hammer mill (U.S. Pat. No. 2,045,688) also consists of a hammer mill rotor which is housed in the bottom part of a housing constructed in the form of a sieve and whose upper portion is partially widened in order to form an abutment chamber, this abutment chamber leading at its upper end to the fill shaft and a chamber for collecting foreign bodies being adjacent the side opposite the abutment chamber. Portions of the grinding goods which cannot be ground up are thrown into the abutment chamber and move from there into the foreign body discharge chamber thus crossing the path of the grinding goods being filled in. It is ob vious that in this type of mill construction the paths of the goods being filled in and the portions flying toward the foreign body discharge chamber continuously cross, thus taking portions belonging into the foreign body chamber back into the mill and, on the other hand, grindable portions of the grinding goods introduced are taken along to the ungrindable portions and move to the foreign body chamber.

A similar disadvantage exists with another known hammer mill, (US. Pat. No. 3,082,963, issued Mar. 26, 1963 to .I. C. P. Gondard), which includes a horizontally disposed hammer rotor in which the grinding goods are fed in from the top through a fill shaft. The hammer rotor is surrounded at its bottom by a mesh grating, a foreign body chamber with discharge flap being provided at the mill housing to accommodate ungrindable objects. The foreign body chamber is here disposed beside a vortex shaft which forms the upward extension of the mill housing and to which the foreign body chamber is connected by means of a common cover.

Due to this configuration, the material to be ground is fed in at random above the beating circle of the hammer rotor.

Foreign elements thrown into the vortex shaft by the heaters fall back into the range of the heaters unless they are immediately discharged. Thus, grinding material components which cannot be comminuted also reach the upper descending quadrant of the rotor and are inevitably pressed onto the sieve by the heaters thus creating unnecessary wear of the mesh grating. Since the foreign body discharge chamber is disposed at the upper end of the vortex shaft, parallel thereto and immediately to the side thereof, the portions which cannot be comminuted can only reach the foreign body discharge chamber by being laterally deflected in a direction which does not correspond to their actual direction of flight. This has the result that the components, which cannot be comminuted and which fall back onto the rotor in haphazard distribution over the entire cross section of the vortex shaft, thus reach, on the one side, the area of the ascending quadrant of the rotor and, on the other side, the area of the descending quadrant of the rotor. The particles reaching the latter area are thus unavoidably pulled into the area between the rotor and the sieve basket. In addition to this drawback there exists the further disadvantage that the fill shaft is attached at a point which is relatively high on the vortex shaft thus incurring the danger that portions of the grinding material which can be comminuted without difiiculties are taken along in an upward direction by the flying ungrindable particles and thus enter into the foreign body discharge chamber.

Finally, two hammer mills are known from US. Pat. Nos. 1,235,868 and 1,420,354 which are very similar to that of the present invention. These two mills essentially correspond in their construction to a mill configuration as mentioned in the introductory paragraph, a configuration of which the present invention is an improvement, since these two mills also at least partially exhibit the drawbacks of the above-mentioned mills, particularly as concerns the crossing of the paths of the introduced grinding material and ungrindable portions. Moreover, the spatial conditions in the mill itself, i.e. particularly in the area of the shaft for the separated material, are too small.

SUMMARY OF THE INVENTION Among the objects of the present invention is the provision of a beater mill in which grindable materials in a mixture of grindable and nongrindable materials are separated in which the possibility of the jamming of nongrindable materials between the rotor and a surrounding sieve is substantially minimized.

It is a further object of the invention to provide such a mill in which the mixture of materials is supplied at a point in which grindable materials are readily driven toward the grate, and nongrindable materials are driven into the discharge chute, and in which nongrindable materials falling back toward the rotor from the discharge chute are deposited in regions from which they may be again driven into the discharge chute, rather than being directed toward the sieve.

Briefly stated, these and other objects are achieved by the provision of a beater mill comprising a fill chute, a rotor carrying rotating heaters partially surrounded by a sieve, and a discharge chute into which the nongrindable materials are driven by the heaters. The bottom surface of the till chute is connected to the rotor housing at a point which is below the top of the rotor so that the mixture flows into the region of the rotating beaters. The discharge chute is positioned tangentially to the rotor so that the heaters drive the nongrindable components into it. Its axis is arranged at an angle to the axis of the till chute and both axes intersect in the quadrant of the rotor facing the fill chute. Accordingly, materials falling back from the discharge chute land in regions from which they will again be driven into the discharge chute and are less likely to become jammed between the rotor and the sieve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a portion of a heater mill according to the present invention.

FIG. 2 is a longitudinal section through the beater mill of FIG. I with some parts broken away or omitted.

FIG. 3 is a full longitudinal section through the beater mill of FIG. 1 including those parts omitted in FIG. 2.

FIG. 3a is a perspective view of a discharge opening of the end portion of the discharge chute.

FIG. 3b is a plan view of the cover, which coacts with the edges of the discharge opening of FIG. 3a.

FIG. 4 is a longitudinal sectional view of a portion of another embodiment of the present invention.

FIGS. 5 and 6 show variations of a detail.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, FIGS. 1 and 2, a beater mill 1, according to the present invention, includes a fill chute 8 which carries material to a rotor 2 having rotating beaters 21, which is enclosed in the lower portion of a housing 3 and is surrounded along its bottom by an arcuate mesh grating 4. A discharge chute 11 is arranged at the upper portion of the housing 3 along a tangent'to the rotor along which heavy nongrindable components are driven by beaters 21. The tangent is a tangential axis beginning substantially in the center of the upper ascending quadrant 15 of the rotor 2. Chute 11 has an axis which is oriented substantially in the direction of said tangential axis and is disposed at an angle to fill chute 8. The axis of chute ll intersects the axis of fill chute 8 outside of the furthest structural extent of the rotor 2. A slanted wall 13 is provided at the upper end of the discharge chute 11 which directs most of the nongrindable materials striking it into a bent portion 22 of the chute and toward a discharge opening 14. Within the discharge chute there is fixed a member 12 including a downwardly sloping slide plate 12' and an abutment plate 5'. Slide plate 12' acts somewhat like a ski jump slide in that materials which fall upon it are given a horizontal component of motion as they slide down. This horizontal component of motion carries them toward that quadrant 15 of the rotor which faces the fill chute 8. The abutment plate 5' extends vertically from the lower end of slide 12' down to the upper edge of that portion of grate 4. Teeth 5" are arranged on the upper region of plate 5' and have their points facing downwardly. Teeth 5" are arranged in the lower region 16 of plate 5 and have their points facing upwardly.

Housing 3 is formed of portions 5 and 6 which are pivoted to a support frame 45 at points and 10 respectively. Sections 5 and 6 meet along a perpendicular separation groove 7. Threaded

spindles

9 and 9 connect the sections 5 and 6, respectively, to frame 22. The sections may be opened by operation of the spindles to permit access to the interior of the mill if required.

Fill chute 8 is part of pivotal section 6. It has a bottom slide surface 8' which meets the vertical interior section of the housing below the level of the top of rotor 3 and above the grate 4.

Chute 8 has a central axis 24 and discharge chute 11 has a central axis 26.

Axes

24 and 26 intersect at a point 28 which is located in the fill quadrant of the rotor. The angle of

axes

24 and 26 to each other is approximatelv 80 although this is not crucial. Bottom plate 8 is arranged in an angle of 30 to 60 to the vertical which facilitates the delivery of materials to the rotor by gravity.

Discharge chute 11 is fixed to the supporting frame 22.

The discharge chute 11 for separated material is provided, at its upper end, with a bent wall 13, which may have the form of an abutment plate and which is disposed in an angular position with respect to the housing wall so that grinding material particles falling thereagainst will move from there to the discharge opening 14 of the shaft 11.

As illustrated in FIG. 3, the device is also provided with a cover 17 which is pivoted to the end of the bent portion of the discharge chute to cover opening 14. A lever arm 13 extends from the cover 17 on the side opposite pivot 34. A weight 19 is adjustably disposed on lever arm 18 to press cover 17 into tight engagement with the edges of the discharge chute. Any

suitable mechanism may be provided to open the cover 17. For example, a cable 20 may be connected to lever arm 18 and passed over a pulley 36 connected to an arm 38 fixed to the chute above the pivot 34. A coacting airtight seal 40 is provided including parts 42 (FIG. 3a) mounted on the edges of the discharge opening 14 and parts 44 (FIG. 3b) mounted on the edges of cover 17 which face the discharge opening.

As shown in FIG. 3a, the airtight seal 40 consists of parts 42, which may be a sealing ring of India rubber, thermoplatic material or the like. The edges of cover 17 coact airtightly with the sealing ring, when cover 17 is closed.

Alternatively, the cover 17 may have parts 44 formed as a sealing plate (shown in FIG. 3b).

Naturally, the cover 17 may be mounted with a sealing ring on the edges like the discharge opening 14 in FIG. 3a instead of a sealing plate.

In another modification, the edges of the discharge opening 14 and the cover 17 may be mounted with airtight sealings including for example a sealing ring and a sealing plate. Such a modification would be a combination of the sealings, shown in FIGS. 3a and 3b.

FIG. 4 discloses a barrier plate 13' which is pivoted to the bent wall portion 13. The pivot 30 of plate 13 is located on the side of the discharge chute 11 facing the fill chute. An adjustment device 32 for fixing the angular position of plate 13 connects the outer end of the plate and wall 13. Pivoted plate 13' pennits the inner diameter of the discharge chute to be varied and makes possible the classifying of grind material particles to be separated.

OPERATION OF A PREFERRED EMBODIMENT Material to be ground is desirably supplied continuously through the fill chute at such a rate that it reaches a fill level extending into the mouth of the fill chute at approximately the point designated F in FIG. 2. This point F is approximately midway between the extension of the central axis of chute 8 and its bottom sliding surface 8. Material to be ground falls practically perpendicularly downward into upper ascending fill quadrant 15 adjacent the ascending beaters 21 which rotate in a counterclockwise direction as indicated in FIG. 2. Grindable components are usually immediately crushed by blows with the beaters so that they are not imparted any significant momentum and can be directly discharged through the mesh grating 4. Ungrindable components, however, are engaged by the beaters 21 and impelled in a substantially tangential direction into the discharge chute l1 and, depending on the amount of energy imparted, either leave the chute directly through the discharge opening 14 or fall back over slide 12 back into the area of the fill quadrant 15.

The shape of the slide illustrated may be varied to conform with the dimensioning of the entire mill, the materials to be ground, and the thrust and the flight conditions. The slide could even be formed with a convex or an acute angle shape, as shown at in FIG. 5 and at 12b in FIG. 6, respectively. The important point is that the design will be so selected that particles sliding down it will be thrown into the fill quadrant after they leave the slide.

Grindable components which are not immediately crushed are thrown to a large extent against the vertical abutment plate 5 or into discharge chute 11. In either case they normally slide back into the range of the heaters 21 of rotor 2 and are probably crushed after the first return since they have been partly crushed already. Those which strike the abutment plate 5 are subject to a comrninuting efiect which is increased by the teeth 5". Moreover, since these teeth face downwardly, they deflect material sliding down the plate outwardly toward the center of the rotor. Accordingly, they help to protect the mesh grating 4 from particles which might otherwise be jammed in between the rotor and the grating. The surface 5' below the slide region 12 may be constructed in any manner which improves this abutment effect. The upwardly facing teeth 5" located in the lower regions in the abutment plate retard the entry of larger grindable particles into the area between the grate and the rotor until they have been beaten into smaller pieces by the beaters 2]. In the unlikely event that some nongrindable particles reach this region, the teeth would prevent, or at least retard further movement of the particles down into the region between the rotor and the grate until the completion of the grinding process or until the pivoted plate 5 were opened for periodic cleaning.

The positioning of the abutment plate 5' so that it extends a substantial distance up into the discharge chute ll shields the housing and the chute walls from heavy flying objects and prevents dents which occur in known mills. This also makes possible the construction of the housing and the chute from relatively lightweight materials.

The construction of the abutment plate also protects, to the greatest possible extent, the mesh grating, and prevents operational malfunctions which occur in other known devices by the jamming of uncrushable parts into the slits of the mesh grating.

Since the wall 5' extends from the descending quadrant of the rotor to a slide area which serves somewhat like a ski jump, it throws back falling material into the ascending quadrant of the rotor. Accordingly, the particles do not fall into the descending quadrant.

Ungrindable particles within the fill quadrant which have any substantial mass ordinarily fly up in a parabolic trajectory when they are struck by the beaters 21. The bent portion 22 of the discharge chute is normally so aligned that it substantially encloses the trajectory of heavier particles having substantial mass and little air resistance, for example solid pieces of metal. Particles with a different trajectory may hit one of the walls of the discharge chute and eventually slide back on the slide plate 112', or may hit the slide plate 12' directly. Such particles, as they slide down, are given a horizontal component of motion similar to that imparted by a ski jump and fall into the fill quadrant. Objects such as a tin can, or other objects made of sheet metal which have substantial air resistance become more and more deformed as a result of repeated collisions with the walls of the chute or other objects and eventually become capable of assuming trajectories which carry them to the discharge opening 14. The arrangement of the bottom sliding surface 8' of the filling chute so that it falls below the highest point of rotor 2 and the filling level F results in a path of movement of the mixture to be ground which does not interfere with the objects falling back from the discharge chute. This is a further result of the fact that the central axis of the discharge chute 11 and the axis of the filling chute 8 intersect in the ascending quadrant 15. Accordingly, the falling objects simply land on top of the moving mixture, or directly in the path of the ascending beaters if the mixture level is low. In either case, the particles tend to be struck repeatedly by the beaters and again be thrown into the discharge chute. Accordingly, depending on the consistency and the shape of the ungrindable particles they are thereby deformed in stages and are thrown back again and'again into the discharge chute until they are ready to leave the chute through opening 14.

The airflow created by the rotor enters the discharge chute llll when the mill is in operation and can not escape therefrom when airtight flap 17 is closed. Accordingly, a column of air under pressure is formed in shaft 11. This column of air acts against textile and paper shreds or other similar light grindable materials which are often blown away from the rotor, and forces them back toward the rotor where they will likely be eventually ground. Consequently, few of such components reach the cover 17 or the discharge opening, and when cover 17 is eventually opened, only ungrindable components, for the most part, are discharged.

If desired, the machine can be shut off before the flap is opened so that such shreds can fall back and no upward flow of air develops in the discharge chute while the cover is opened.

The supply of material to be ground can also be interrupted before the cover is opened, and the machine can be kept running thereafter so that all accumulated volatile particles may be ground and none are present in the chute when the cover is eventually opened.

This feature may be particularly useful when the mill is used for the processing of refuse, and in which the refuse is delivered to the mill by conveying devices. By appropriate switching the conveyor belt delivering material may be stopped, and after a suitable interval the cover 17 may be opened by a relay.

The adjustable roof plate 13' is particularly useful in grinding waste wood, tree trunk sections, or the like. Such material is comminuted into long chips when it first passes through the region between the rotor and grating 4. Such chips should be further ground until they are small enough to pass through the grating which may be made with apertures of suitable size to form chips of the final size desired for such purposes as conversion into pulp, etc. Long pieces of wood which are thrown up by the rotor into the discharge chute strike the plate 13' which prevents the large pieces of wood from flying out of the discharge opening. Such long chips which strike the plate and fall back toward the rotor are likely to be oriented with their fibers transverse to the heaters by the time they return to the rotor, as a result of the actions which take place as the long chips hit the plate and slide or roll down slide 12. It is possible to position plate 13' in such a manner that only certain defined pieces, for example branches attached to the wood are passed through to the discharge opening. Users of the machine can learn how to make such adjustments as a result of their experience. Pieces of metal enclosed in the wood, such as nails, screws, iron hoops positioned in beams and the like leave the mill through the discharge opening.

it will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations.

lclaim:

1. ln a beater mill for separating nongrindable materials and grinding the grindable material in a mixture, said mill comprising, in combination:

a. a housing having upper and lower portions;

b. a heater mill rotor means mounted for rotation in a direction of rotation within the housing and having rotating beaters defining a furthest structural extent and a tangential axis beginning substantially in the center of the upper ascending quadrant of said rotor means and a sieve fixed in said housing adjacent the bottom of the rotor means for passage therethrough of ground material;

c. a fill chute defining an axis and attached to the upper por tion of said housing adjacent said upper ascending quadrant for delivery of said mixture of material to the rotor means;

d. a discharge chute means attached to the upper portion of said housing adjacent said fill chute in the direction of rotation of said rotor means for discharge of nongrindable material and oriented substantially in the direction of the tangential axis of the rotor means for receiving particles driven off by the beaters, and having an axis which is disposed at an angle to the fill chute and which axis intersects the axis of the fill chute outside of the furthest structural extent of the rotor means; the improvement in which:

. said fill chute has a bottom surface arranged at an angle substantially in the range of 30 to 60 to the vertical, and which is attached to the side of the housing at a point below the greatest height of the rotor, which bottom surface has an imaginary extension which is approximately parallel to the fill chute axis, and

2. the discharge chute being arranged so that its axis intersects the axis of the fill chute within that quadrant of the rotor which faces the fill chute.

2. The beater mill of claim 1 in which said sieve has a semicircular cross section and the discharge chute has a discharge opening at one end, and a wall which is disposed at an angle to both the discharge opening and the axis of the discharge chute.

3. The beater mill of claim 1 including additional slide plate means mounted within the discharge chute for directing materials within the chute falling back toward the rotor into the rotor quadrant facing the fill shaft.

4. The beater mill of claim 1 including a member having an abutment plate mounted within the housing opposing the till chute and facing the rotor, and a slide plate attached at an angle to the abutment plate at its upper end.

5. The beater mill defined in claim 4 wherein the abutment plate has teeth facing the rotor whose tips point downwardly.

6. The beater mill of claim 4 including teeth mounted on the abutment plate whose tips point upwardly.

7. The beater mill defined in claim 4 wherein the abutment plate has a plurality of teeth facing the rotor, those which are above the top of the rotor having tips which face downwardly and those which are below said top having tips which face upwardly.

8. The heater mill of claim 1 wherein the housing includes a supporting frame to which said discharge chute is attached, and wall sections pivoted to the frame for movement from a first position in which they are part of a closed housing to an open position which permits access to the rotor.

9. The beater mill defined in claim 2 including a barrier plate pivoted to the discharge chute adjacent its opening for movement to various angular positions relative to the discharge chute axis.

10. The beater mill defined in claim 1 including an opening in the end of the discharge chute, and cover means secured to the chute for selectively closing the said opening.

11. The beater mill of claim 10 including means providing an airtight seal between the cover means and the edges of the discharge opening.

12. The beater mill defined in claim 11 in which said airtight seal includes sealing means mounted in the edges of the discharge opening and the cover means has a pivotal cover flap formed to engage said sealing means and extend beyond the discharge opening edges.

13. The beater mill defined in claim 11 wherein the airtight seal is mounted on the edge areas of the cover means which face the edges of the discharge opening.

14. The beater mill defined in claim 12 wherein the edges of the discharge opening and the associated edges of the cover means have coacting seals.

Claims

1. In a beater mill for separating nongrindable materials and grinding the grindable material in a mixture, said mill comprising, in combination: a. a housing having upper and lower portions; b. a beater mill rotor means mounted for rotation in a direction of rotation within the housing and having rotating beaters defining a furthest structural extent and a tangential axis beginning substantially in the center of the upper ascending quadrant of said rotor means and a sieve fixed in said housing adjacent the bottom of the rotor means for passage therethrough of ground material; c. a fill chute defining an axis and attached to the upper portion of said housing adjacent said upper ascending quadrant for delivery of said mixture of material to the rotor means; d. a discharge chute means attached to the upper portion of said housing adjacent said fill chute in the direction of rotation of said rotor means for discharge of nongrindable material and oriented substantially in the direction of the tangential axis of the rotor means for receiving particles driven off by the beaters, and having an axis which is disposed at an angle to the fill chute and which axis intersects the axis of the fill chute outside of the furthest structural extent of the rotor means; the improvement in which: 1. said fill chute has a bottom surface arranged at an angle substantially in the range of 30* to 60* to the vertical, and which is attached to the side of the housing at a point below the greatest height of the rotor, which bottom surface has an imaginary extension which is approximately parallel to the fill chute axis, and 2. the discharge chute being arranged so that its axis intersects the axis of the fill chute within that quadrant of the rotor which faces the fill chute.

4. The beater mill of claim 1 including a member having an abutment plate mounted within the housing opposing the fill chute and facing the rotor, and a slide plate attached at an angle to the abutment plate at its upper end.

8. The beater mill of claim 1 wherein the housing includes a supporting frame to which said discharge chute is attached, and wall sections pivoted to the frame for movement from a first position in which they are part of a closed housing to an open position which permits access to the rotor.