Reversible material reducing mill

A reducing mill for handling a wide variety of trash and waste material needing reduction to a state for easy subsequent handling and for separating certain components of the material by a specific gravity characteristic. The reducing mill embodies means for mixing and segregating components of the trash and waste material by the combined jet and negative pressure gradient induced by the action of an air stream, and by the cooperation of a hammer mill housed in a casing formed to effect recycling of material which needs or may require recirculation for further reduction and segregation.

BACKGROUND OF THE INVENTION 
This invention relates to trash and waste material reducing apparatus, and 
is particularly directed to improvements in the effective handling and 
reduction of such materials in a hammer mill. 
Material reducing apparatus which has preceded the present apparatus has 
embodied the use of air for moving the material as in Williams U.S. Pat. 
No. 3,702,682 of Nov. 14, 1972, or has embodied reversible hammer rotors 
and control over the position of breaker plates as in Williams U.S. Pat. 
No. 3,667,694 of June 6, 1972. Other prior art includes Leggett U.S. Pat. 
No. 1,751,009 of Mar. 18, 1930; Hartshorn U.S. Pat. No. 2,287,799 of June 
30, 1942; Gondard U.S. Pat. No. 3,082,963 of Mar. 26, 1963; and Meyer U.S. 
Pat. No. 3,442,458 of May 6, 1969. However, the present mixing and 
segregation of the various fractions of trash and waste material by a 
controlled air stream and vacuum agitation is new and unique over the 
foregoing examples of the prior art. 
The general objects of the present invention are to combine in a unique way 
a hammer mill in a housing with a more efficient and positive manner of 
mixing and segregating waste material and trash in an air stream, and to 
provide means in the housing for subjecting the trash and waste to a 
controllable air stream which breaks up clustered material and allows the 
heavy material to fall out and not get trapped in a recirculating orbit, 
or return to the hammer mill more than a minimum number of times. 
A more specific object of the present invention is to provide a 
controllable high velocity air stream past the delivery end of material 
feeding means, and provide a negative pressure gradient or partial vacuum 
area adjacent the delivery end of the feeding means for effecting a 
thorough mixing and jet action. 
A further object of the present invention is to provide a material reducing 
mill of reversible character in combination with the structure and means 
pointed out above and to be described below, all of which provides 
improved results.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
Referring now to the drawings, and particularly to FIG. 1, there is shown a 
sectional elevational view of the material reducing mill in which the 
enclosure 10 provides an upper material mixing area 11 and a lower 
material reducing area 12 arranged in substantially vertically related 
communication. The upper material mixing area is provided with an arched 
wall 13 which has an extremity 14 disposed so that material following the 
curvature of the arched wall 13 will be directed into feeding means 15 so 
as to return to the trash and waste material being transported by the 
feeding means toward its discharge end 16 which is in the mixing area 11. 
The feeding means comprises a tray structure connected by its bottom wall 
17 to an eccentric member 18 driven by motor 19. The bottom wall 17 is 
supported on a plurality of springs 20 in combination with links 21 so 
that the feeding means 15 will be caused to vibrate in a generally 
horizontal plane but with the result that trash and waste material 
deposited therein by a supply conveyor C will be advanced toward and pass 
off the discharge end 16. Of course, side walls are provided in order to 
complete the enclosure 10. 
The material reducing area 12 (FIG. 1) is constructed and arranged to 
support a rotary hammer assembly 22 in which a shaft 23 carries a 
plurality of supports 24 for the purpose of forming the connection for 
hammers 25 which are connected to the supports 24 on suitable pivot pins 
26. It can be seen that the reducing area 12 is provided with breaker 
plates 27 arranged on opposite sides of the rotary hammer assembly 22. The 
breaker plates 27 are pivotally supported on shafts 28 at their upper 
ends, while the lower ends are provided with shafts 29 which are adapted 
to project outwardly of the side wall structure through suitable slots 30 
which have a curved form with the center thereof substantially in the axis 
of the pivot shafts 28. The rotary hammer assembly, below the breaker 
plates 27, is enclosed by a cage assembly 31 made up of a plurality of 
cage bars 32 providing openings for the passage of the material which has 
been reduced by the action of the rotary hammers 25 to a size that will 
pass through the cage bar openings. 
FIG. 1 also shows that the arched wall 13 over mixing area 11 has a portion 
thereof defined by a hood structure 34 extending over a part of the 
feeding means 15. The hood structure 34 is provided with an end wall 35 
which supports an adjustable curtain 36 pivoted at 36A on the end wall 35 
and projecting into the feeding means 15 for limiting the passage of air 
between the exterior and the mixing area. In addition to the curtain 36, 
the hood structure supports a deflector plate 37 which may be adjusted in 
position along its arcuate path 38 so as to deflect heavy objects which 
may get into the area adjacent the plate 37. The deflector plate 37 acts 
as a guard for an air outlet port 39 which opens through the hood 34 and 
connects with a conduit 40. 
The view of FIG. 2 shows conduit 40 connected to a cyclone separator 41 
where lightweight objects and dust can be centrifugally extracted and 
discharged from the separator 41 through a rotary valve 42. Additionally, 
air is moved from the material reducing area 12, along with dust and 
fines, by conduit 40A which connects up with conduit 40 in advance of the 
cyclone separator 41. Air which has been centrifugally cleaned in the 
separator 41 is returned through a conduit 43 to the inlet side of a 
blower 44. The blower is mounted on a suitable base in a position below 
the supporting structure 45 for the vibratory feeding means 15, and is 
driven by a suitable motor (not shown). 
The blower 44 has its discharge conduit 46 connected to an air flow conduit 
47 (FIG. 1) which extends through the side wall 12A of the area 12 and is 
formed with a discharge end 48 located in the mixing area 11 adjacent the 
discharge end 16 of the feeding means 15. There is a pocket 49 formed just 
below the discharge end 16 of the feeding means by a suitable wall 50 
which is connected to or may be a part of the conduit 47 but directed 
laterally with respect to the longitudinal axis of such conduit. Lateral 
wall 50 is connected to the vibratory feeding means by a flexible wall 51 
so that the action of the feeding means 15 will not be restricted by the 
conduit 47. It can be seen in FIG. 1 that the conduit 47 is formed with a 
chute 52 which extends downwardly from the underside of the conduit 47 so 
that material passing downwardly through the conduit 47 may enter the 
chute 52 at the opening 53. The bottom end 54 of the chute 52 is adapted 
to be open to allow air to flow inwardly to conduit 47, and a suitable 
conveyor 52A is positioned to catch the material and move it to a suitable 
location. 
It has been discovered in controlling the velocity of the air stream moved 
through the conduit 47 and past the pocket 49 that material passing off 
the discharge end 16 of the feeding means 15 is drawn into the pocket 49 
prior to being picked up in the air flow through the discharge end 48 of 
the conduit 47. It has also been discovered that control over the movement 
of the material into the pocket 49 and then into the mixing area 11 can be 
obtained by the presence of a movable gate 55 slidably supported on a wall 
of the chute 52 and directed so as to project across a portion of the 
conduit 47 for the purpose of varying the velocity of the air stream in 
the conduit 47. The gate 55 is held in moved position by one or more 
threaded holding elements 55A. 
The presence of the gate 55 controls the velocity of the air flow past the 
pocket 49 with the result that a negative pressure gradient is produced in 
the pocket 49 and material leaving the discharge end 16 of the feeding 
means 15 is flipped over and turned so the material that is vibrated to 
the bottom layer in means 15 will be released from being trapped under 
larger material as the material moves into the pocket by the flow of air 
induced by the negative pressure gradient before being picked up in the 
high speed air stream and propelled into the mixing area 11. During the 
movement of the material into pocket 49, it will gain velocity such that 
the portions of higher specific gravity and larger size will be induced to 
fall through the high speed air stream and pass out through discharge 
chute 52, while the smaller and lighter weight components will pass into 
the area 11 and fall into the area 12 for reduction by the rotary hammer 
assembly 22. The portions falling through the high speed air stream will 
be subjected to a scrubbing action which will strip off most lightweight 
fractions which still cling to the portions destined to fall through the 
high speed air stream. 
Referring now to FIG. 3, there is shown a modification of the air flow 
control means. In this structure, a full Venturi throat 56 is created by 
mounting a stationery throat element 57 on the wall of the conduit 47, and 
providing a movable Venturi throat wall 58 on a plate 59 which would 
replace the flat plate 55 shown in FIG. 1. The Venturi has been found to 
be more energy efficient than the flat plate type orifice. 
The action of the adjustable plate 55, or that of the Venturi forming means 
57 and 58, is believed to be one in which the flow of air entering conduit 
47 is squeezed down and experiences an increase in velocity with a 
reduction in pressure. The air after passing the plate 55 expands in an 
effort to fill the volume of the conduit space 47A. However, the blower 48 
cannot supply the deficiency so air is drawn in through chute 52 and 
further air is drawn in from the feeder 15 over its discharge end 16. The 
latter air flow flips the material into the pocket 49 and causes it to 
tumble and to turn over, which aids in the break up of clusters of 
material and entrapped granular material. The mixing, tumbling and other 
motions imparted to material in or entering the pocket 49 is responsive to 
the selected position of the plate 55, or the Venturi portion 58, such 
that adjustments can be made to suit the character of the trash and waste 
material being processed. Moreover, it has been found that the material 
drawn with air over the discharge end 16 of the feeder means 15 increases 
its downward velocity and improves the normal gravity separation of heavy 
objects of a non-crushable type by adding the velocity effect to the 
gravity effect. 
It has been pointed out that the breaker plates 27 are movable for 
controlling the path of travel of material thrown back into the mixing 
area 11 by the assembly 22. Each breaker plate 27 has the opposite ends of 
the shafts 29 connected to hydraulic cylinders (FIG. 4) arranged such that 
the left cylinders 60L move its plate 27 in a direction opposite to the 
way the right cylinders 60R move its plate 27. Thus, as the right hand 
breaker plate is moved toward the hammer assembly 22, the left hand 
breaker plate 27 is moved back or away from the hammer assembly 22. The 
system for supplying pressure fluid to the cylinders includes a pump 61 
driven by motor M and supplied with hydraulic fluid from a reservoir 62. 
The pump 61 delivers fluid to a reversing valve 63 which is responsive in 
one setting to spring 64 and in an opposite setting to a solenoid 65. 
Thus, the supply conduit 66 and return conduit 67 can be reversed in 
function as is indicated by the full line and broken line positions of the 
plates 27 in FIG. 1 by shifting the valve 63 through manipulation of the 
solenoid 65. 
The position of the breaker plates 27 is determined by the direction of 
rotation of the hammer assembly 22 so that the right hand breaker plate 27 
first encountered by the direction of travel of the hammers 25 (see FIG. 
1) performs the material shredding reduction and the opposite or left hand 
breaker plate 27 is moved away from the path of travel of the hammers 25 
so as to guide any non-crushables thrown out by the hammers into the 
mixing area 11 for cooperation with the arched wall 13. The material 
thrown out in this manner is directed by the arched wall 13 to return to 
the feeder means 15 where it can co-mingle with the trash and waste 
material and move into the pocket 49. Thus, if the returned material 
possesses the necessary specific gravity, it may escape through the 
conduit 47 and fall into the chute 52. The arrangement of the apparatus 
enables non-crushables entrapped in the trash and waste material to be 
disassociated by impact with the rotary hammer assembly and to be returned 
to the feeding means 15 for subsequent escape. 
It is observed in FIG. 1 that if the right hand breaker plate 27 is moved 
to the broken outline position there is provided a gap or space 68 between 
the bottom of such plate and the adjacent grate bar 32R. This space 68 is 
provided so that should hard-to-reduce material remain in the reducing 
area 12 or keep returning thereto, the operator can move valve 63 to 
reverse the position of the breaker plates 27 such that the right hand 
breaker plate will move to open the gap 68 and allow that material to 
escape by by-passing the grate 31. When it becomes necessary to reverse 
the breaker plates 27 to rid the mill of some hard-to-reduce object, it is 
within the control of the operator to reverse the normal rightward travel 
of conveyor belt 69 so that the object allowed to by-pass the grate 31 
through space 68 can be dumped onto conveyor 52A where it will be moved to 
a suitable location with material falling onto conveyor 52A. It is 
considered conventional to be able to reverse the normal rightward travel 
of the conveyor 69 and any suitable reversible drive (not shown) for that 
conveyor may be employed. Observing the indicated direction of rotation of 
assembly 22 in FIG. 1, the breaker plate 27 in the moved-in position is 
the operative plate and the opposite breaker plate is positioned for 
guiding the hard-to-reduce material upwardly to follow the arched wall 13. 
When a hard-to-reduce fraction repeatedly returns to the assembly 22 the 
inbreaker plate can be moved back to open the escape space 68. 
FIG. 1 shows the further arrangement of means to sort out objects in the 
stream of trash and waste material so as to avoid the chance that such 
objects might become lodged in the conduit 47 and disrupt the intended 
operation. The feeding means includes a sorting device 70 disposed in the 
open top feeder 15 to which conveyor C delivers the waste. The device 70 
(FIGS. 1 and 5) is composed of an array of tubular elements 71 each fixed 
to the upper longitudinal margin of a thin sheet 72, the bottom edge of 
each sheet 72 is secured to the bottom wall 17 of the vibratory tray 
structure which is vibrated longitudinally and causes objects falling onto 
the tubes 71 to fall through the spaces between tubes 71 and be collected 
in the tray structure. The large objects do not fall through the spaces 
but are caused to be vibratorially advanced to a position where they fall 
off the ends 73 and onto a slanted chute 74. The chute diverts the 
oversize objects off to one side of the tray where they can be processed 
by other means. The waste objects which are able to pass through the 
spaces between elements 71 are advanced off the end 16 and treated as 
above described. It can be appreciated that the presence of the sorting 
device 70 keeps large objects out of the stream of objects and 
accomplishes the intended purpose which is to prevent having to dismantle 
the assembly when an oversize object gets stuck in the conduit space 47A. 
The space between elements 71 is related to the size of the space 47A.