CN100516392C - Impurity treating apparatus - Google Patents

Abstract

The present invention provides an inclusion processing device capable of improving the durability of a sieve device, preventing retention of inclusions, and efficiently and reliably collecting inclusions into a pulverizer. The arc-shaped sieve parts (45) are spaced and stacked in the vertical direction, and the rake shaft (47) with a plurality of rakes (46) moving between the sieve parts is arranged so as to be aligned with the center of the outer peripheral edge of the sieve parts ( 45o) is eccentric, so that the front end of the rake emerges from the outer peripheral edge of the screen member, and the collected inclusions are collected by the rake. In addition, the rear side of the arc-shaped sieve member is opened to prevent the stagnation of inclusions inside, reduce water flow resistance, and improve the durability of the sieve device (40). The outer peripheral edge of (45) is easy to peel off inclusions, and between the position where the rotating rake points before the pulverizer and the position pointing to the pulverizer, the flow of treated water toward the pulverizer can be formed.

Description

Inclusion processing device

technical field

The invention relates to an inclusion treatment device for collecting and crushing inclusions in treated water such as sewage.

Background technique

When inclusions such as empty cans, plastic containers, and wood chips flow into sewage treatment facilities together with sewage (water to be treated), they can cause accidents such as clogging and damage to pipes and pumps in the sewage treatment facilities. The device of this kind of accident, the device described in patent document 1 and patent document 2 is known. As shown in Figure 7, the device described in Patent Document 1 is to assemble an annular open mesh screen 2 and a pulverizer 1 in the sewer, collect impurities in the sewage with the annular open mesh screen 2, and It is fed into a pulverizer 1 with which it is finely pulverized and dispersed in the sewage.

In addition, as shown in FIG. 8 , the device described in Patent Document 2 sets the fixed grid screen 3 to obliquely intersect with the waterway, and a pulverizer 4 is provided at the downstream end of the screen 3 , and the grid screen 3 is provided with a The scraper 5 at the end scrapes off the impurities flowing along the screen 3 to the pulverizer 4 and sends them into the pulverizer 4 .

Patent Document 1: Japanese Patent Publication No. 7-85781

Patent Document 2: Japanese Patent Application Laid-Open No. 8-226165

However, the device described in Patent Document 1 has the following problems. The screen portion of the mesh screen 2 moving on a substantially elliptical rotating track is made of a flexible material such as polyethylene/nylon. Therefore, it is difficult to make the screen portion strong, and the screen portion is easily damaged, resulting in poor durability. question. In addition, the sieve is an infinite circulation type, so the sieve is double-layered and the water flow resistance is large, which will hinder the passage of sewage, and the inclusions that have passed the front side are difficult to discharge from the rear side and remain inside the sieve. There is a problem that it is difficult to work. In addition, since the sieve is a belt surface woven into a net shape, inclusions are likely to be caught by the irregularities, and there is a problem that once the inclusions are caught, it is difficult to release them.

In addition, in the device described in Patent Document 2, as the water flow becomes faster, the component force in the flow direction of the water flow is too large compared with the component force that moves the inclusions along the grid screen, and the inclusions will be squeezed on the grid screen. The problem of stagnation due to being unable to move along the grid screen.

Contents of the invention

The present invention was made to solve the above-mentioned problems, and its object is to provide a foreign matter treatment device that can improve the durability of the sieve device, reduce water flow resistance and allow water to pass smoothly, and foreign matter does not stay Blockage in the sieve unit effectively and reliably collects inclusions in the shredder.

In the inclusion processing device of the present invention, a sieve device for collecting inclusions in the water to be treated and a pulverizer for crushing the inclusions collected by the sieve device are arranged side by side to cross the water channel, and it is characterized in that the sieve device and The pulverizers are arranged close to each other, and the sieve device has: a plurality of arc-shaped sieve parts spaced from each other and stacked in the up-down direction; A plurality of rakes that move among the rakes; a rake shaft that supports these rakes and extends in the vertical direction; and a water flow guide that rotates together with the rake shaft and points to a position before the pulverizer from the position where the rotating rake points to the pulverizer Between them, the flow of treated water toward the pulverizer can be formed. The pulverizer has a cutting blade that rotates with the vertical direction as the axis and can pulverize the inclusions. , Thus, the front end of the rake emerges from the outer peripheral edge of the arc-shaped sieve member, and the foreign matter collected in the sieve device is raked up and can be collected in the pulverizer.

With the foreign matter processing device constructed in this way, the arc-shaped sieve members are stacked in the vertical direction, and the rake shafts having a plurality of rakes that move between the arc-shaped sieve members are arranged in contact with the outer peripheral edge of the arc-shaped sieve members. The center is eccentric, so that the front end of the rake emerges from the outer peripheral edge of the arc-shaped sieve, and the inclusions collected by the arc-shaped sieve can be raked up. Therefore, the inclusions do not stay or get caught on the arc-shaped sieve member, the water flow resistance can be reduced to allow the water to be treated to flow smoothly, and the inclusions can be reliably collected into the pulverizer. In addition, since the rear side of the arc-shaped sieve member is opened, stagnation of inclusions in the arc-shaped sieve member can be prevented. In addition, since the water flow resistance is reduced, the stress on the sieve device can be reduced, and the durability of the sieve device can be improved. In addition, the sieve device has a water flow guide plate that rotates together with the rake shaft, and can form a flow of treated water toward the pulverizer between the position where the rotating rake points to the position before the pulverizer and the position that points to the pulverizer. flow; therefore, the collected inclusions are easily peeled off from the outer peripheral edge of the arc-shaped sieve member, and the inclusions can be collected into the pulverizer more efficiently and reliably.

In addition, if the structure is such that the outer peripheral edge of the rotating track of the cutting blade is close to the outer peripheral edge of the arc-shaped sieve member, and in the vicinity, the front end of the rake is submerged in the outer peripheral edge of the arc-shaped sieve member, then it can be greatly reduced. The inclusions flowing out between the crusher and the screen device to the downstream side can effectively and reliably collect the inclusions into the pulverizer.

Here, the rotation speed of the rake is preferably less than or equal to 70% of the rotation speed of the cutting blade, so that the inclusions picked up by the rake can be easily introduced into the pulverizer, and the inclusions can be collected into the pulverizer more effectively and reliably.

In addition, when the rake is made of an elastic body, the rake can be properly elastically deformed when foreign matter such as hard wood is caught between the rake and the pulverizer, so that the rake is not likely to be damaged.

In addition, if the water flow guiding parts are arranged at equal intervals along the circumferential direction, one rake in the circumferential direction acts against the water flow and hinders the rotation resistance, but the other rake located on the opposite side of one rake, The force promoted by the water flow can properly disperse the water flow resistance of each rake, so the rotational power of the rake shaft can be controlled to realize energy saving.

Invention effect

The present invention can provide a treatment device for inclusions, which can improve the durability of the sieve device, reduce water flow resistance and allow water to pass through smoothly, and the inclusions will not stay in the sieve device and hinder the operation, and can be effectively and reliably collected in the sieve device. in the shredder.

Description of drawings

FIG. 1 is a plan view showing an inclusion processing device according to an embodiment of the present invention;

Fig. 2 is a schematic sectional view showing the setting of the wedge-shaped liner in Fig. 1;

Fig. 3 is a longitudinal sectional view showing the sieve device among Fig. 1;

Figure 4 is a top view showing the rake in Figure 3;

Figure 5 is a side view showing the rake and the water flow guide plate in Figure 3;

Fig. 6 is a side view showing the fixing part in Fig. 3;

Fig. 7 is the oblique view showing existing device;

Fig. 8 is a plan view showing another conventional device.

Detailed ways

Next, preferred embodiments of the inclusion processing apparatus of the present invention will be described with reference to the accompanying drawings. In addition, in the description of the drawings, the same or corresponding elements are given the same reference numerals, and repeated descriptions are omitted. Fig. 1 shows a plan view of an inclusion processing device according to an embodiment of the present invention, Fig. 2 is a schematic sectional view showing the installation of a wedge-shaped liner in Fig. 1 , and Fig. 3 is a longitudinal sectional view showing a screen device in Fig. 1 , and Fig. 4 is a plan view showing the rake in FIG. 3 , FIG. 5 is a side view showing the rake and the water flow guide plate in FIG. 3 , and FIG. 6 is a side view showing the fixing member in FIG. 3 .

As shown in Figure 1, the inclusion treatment device 100 is installed in a water channel 10 with a rectangular cross-section formed by the bottom 10a and side walls 10b, 10c, and is used to collect and crush impurities in the treated water such as sewage flowing through the water channel 10, It has: a sieve device 40 that collects foreign matter when the water to be treated passes and conveys the collected foreign matter, and crushes the foreign matter conveyed from the sieve device 40 and the foreign matter in the passing water to be treated The shredder 30. In addition, inward (inward in the width direction) slopes 10d, 10e are formed on the side walls 10b, 10c of the water channel 10 to form a flow of the water to be treated toward the screen device 40 and the pulverizer 30 . Thereby, it is possible to prevent foreign matter from accumulating on the bottom 10a on the side wall side of the water channel 10 .

These pulverizers 30 and sieve devices 40 are arranged so as to be close to each other within an assembly frame 90 provided so as to cross the water channel 10 . Positioning pins (not shown) for positioning the sieve device 40 and wedge liners 91 to 93 for positioning the pulverizer 30 are provided in the mounting frame 90 . The positioning pins are set upright at predetermined positions on the bottom of the assembly frame 90. As shown in FIG. ~93a. As shown in Figure 1 and Figure 2, among the wedge-shaped lining plates 91-93, the wedge-shaped lining plates 91, 93 arranged on the two outer sides are arranged at the lower part of the assembly frame 90; the wedge-shaped lining plates 92 arranged at the center are arranged on the assembly frame The upper part of 90.

As shown in Figure 1, the pulverizer 30 is arranged on the side wall 10c side (the right side of the figure) of the assembly frame 90. The introduction port 30b is formed behind the discharge port 30c for discharging the water to be treated. The discharge port 30c communicates with the downstream side through a discharge port 90b formed in the mounting frame 90 . The pulverizers 30 are arranged side by side in the width direction of the water channel 10 so as to rotatably support two rotating pulverizing blades (cutting blades) 32, 32 around an axis extending in the vertical direction (perpendicular to the paper surface), and make the blades mesh with each other. In addition, the pulverizer 30 has a vertical motor (not shown) for rotationally driving the rotary pulverizing blades 32 , 32 at its upper portion.

In addition, in this pulverizer 30, by driving a vertical motor, the rotary pulverizer blades 32, 32 are rotated in a direction in which inclusions are involved, and the water to be treated is introduced from the inlet 30b and discharged from the discharge port 30c through the pulverizer 30, and, At this time, the foreign matter in the water to be treated and the foreign matter conveyed from the sieve device 40 are sandwiched between the rotating crushing blades 32 and 32 to be crushed and released to the downstream side.

In addition, wedge-shaped liners 36 to 38 for positioning the pulverizer 30 with respect to the above-mentioned mounting frame 90 are provided in the pulverizer 30 . As shown in FIG. 2 , the wedge liners 36 to 38 are provided on the rear outer wall surface 30 a of the pulverizer 30 , and are arranged at positions facing the wedge liners 91 to 93 provided on the mounting frame 90 . The wedge-shaped lining plates 36-38 have slopes 36a-38a facing obliquely downward; the wedge-shaped lining plates 36, 38 arranged on the two outer sides are arranged at the bottom of the pulverizer 30; Upper configuration. In addition, the inclined surfaces 36a-38a of the wedge-shaped liners 36-38 provided on the pulverizer 30 are in surface contact with the inclined surfaces 91a-93a of the wedge-shaped liners 91-93 provided on the assembly frame 90, respectively, so that the pulverizer 30 can be guided. And locate it at the predetermined position of the assembly frame 90 .

As shown in FIG. 1 , the sieve device 40 is provided adjacent to the obliquely left front side of the pulverizer 30 in the mounting frame 90 . As shown in FIG. 3 , the sieve device 40 has: a plurality of arc-shaped sieve members 45 spaced from each other and stacked in the vertical direction; 45 a plurality of rakes 46 that move between each other; a rake shaft 47 that supports these rakes 46 and extends in the vertical direction; and a vertical motor 48 that rotationally drives the rake shaft 47 .

The arcuate sieve member 45 has a flat plate shape, and, as shown in FIG. 1 , has a substantially arcuate shape in plan view. Specifically, along the side wall 10b side of the water channel 10 (the left side in the figure), from the oblique rear of the axis 45o in the arc-shaped sieve member 45 to the side of the axis 45o, a straight line is formed, and from the axis 45o The side of the side wall 10b side to the front, until the side and rear of the side wall 10c side are arc-shaped. In addition, the arc-shaped sieve member 45 has its rear side wall 10b side opened, and the water to be treated passing through the arc-shaped sieve member 45 is discharged rearward.

As shown in FIGS. 1 and 3 , the arc-shaped sieve members 45 are spaced apart in the vertical direction, and are fixed to a plurality of pillars 49 extending in the vertical direction by welding. Between the arc-shaped sieve members 45 is a hole through which the water to be treated passes, and inclusions larger than the holes are blocked by the arc-shaped sieve members 45 . In addition, in this embodiment, the plate thickness in the vertical direction of the arc-shaped sieve members 45 is about 9 mm, and the interval t in the vertical direction between the arc-shaped sieve members 45 is about 16 mm.

The rake 46 is made of a planar elastic body such as hard rubber. Furthermore, the rake 46 may be formed of other elastic bodies such as rubber and leaf springs. As shown in FIG. 4, the front end portion of the rake 46 forms an inclined surface 46a, and the length of the radial direction of the front side end portion of the inclined surface along the rotation direction of the rake 46 is longer than the radial length of the rear side end portion on the opposite side. Long length. The inclination angle θ of the inclined surface 46a is preferably 10° to 45°. And, on the contrary, when the length of the radial direction of the back side end along the rotation direction of the rake 46 is formed, the inclined surface is longer than the radial length of the opposite surface side end, the inclusions are If the front end of the moving rake rotates, foreign matter cannot be conveyed well. As shown in FIGS. 3 to 5 , the rake 46 is fixed to a rectangular water flow guide plate (water flow guide portion) 50 extending in the vertical direction.

On one end surface of the water flow guide plate 50 extending in the vertical direction, the plurality of rakes 46 are arranged in parallel in the vertical direction and extend in the horizontal direction. In addition, the water flow guide plate 50 has a plurality of openings 50a for screwing in bolts, and, as shown in FIGS. . The water flow guide plate 50 and the rake shaft 47 rotate together to change the flow direction of the water to be treated. Between the position where the rotating rake points to the position before the pulverizer and the position that points to the pulverizer, the direction of the treated water towards the pulverizer 30 is formed. The flow of water easily peels off the collected inclusions from the outer peripheral edge of the arc-shaped sieve member 45 . The water flow guide plates 50 are arranged at equal intervals in the circumferential direction (90 degrees in the present embodiment) in plan view. Therefore, the resistance caused by the water to be treated can be dispersed and uniformed (details will be described later). And, the water flow guide plate 50 of the uppermost layer, as shown in FIG. By changing the number of strings of the uppermost water flow guide plate 50, it can be applied to various waterways with different waterway heights.

As shown in Figure 6, the fixing member 51 has a pair of half-cut cylinders 52, 53 divided in the axial direction, and a plurality of plate-shaped fixing pieces 54 extending in the vertical direction and fixing the water flow guide plate 50 are protrudingly provided on the side thereof. (In addition, only one of them is described in FIG. 6). The fixing pieces 54 are arranged at equal intervals of 90 degrees in the circumferential direction. In addition, an opening 54a is formed at a position corresponding to the opening 50a of the water flow guide plate 50 of the fixing piece 54; as shown in FIG. The fixing members 51 are connected to each other.

As shown in Figure 3, the two ends of the rake shaft 47 are supported by bearings 56, 57, the bearing 56 on the lower end side is connected to the arc-shaped sieve member 45 of the lowermost layer, and the bearing 57 on the upper end side is connected to the arc-shaped sieve member 45 on the uppermost layer. The members 45 are connected, and the rake shaft 47 is provided at a position deviated from the center 45o (see FIG. 1 ) of the outer peripheral edge of the arc-shaped sieve member 45 . That is, the rake shaft 47 is arranged to be eccentric with the center 45o of the outer peripheral edge of the arc-shaped sieve member 45, whereby the front end portion of the rake 46 that rotates goes in and out from the outer peripheral edge of the arc-shaped sieve member 45, and moves on the arc-shaped sieve. Near the position where the outer peripheral edge of the member 45 is close to the outer peripheral edge of the rotation track of the rotary crushing blade 32 is submerged, the inclusions collected by the sieve device 40 can be raked up and collected into the pulverizer 30 . In addition, in the present embodiment, the distance x between the outer peripheral edge of the rotation track of the rotary crushing blade 32 and the outer peripheral edge of the arc-shaped sieve member 45 is about 7 mm. In addition, the sieve device 40 having these arc-shaped sieve members 45, rake 46, rake shaft 47, water flow guide plate 50, etc. has a positioning hole (not shown) that fits the positioning pin of the above-mentioned assembly frame 90 in its lower part. .

Next, a method of installing the foreign matter processing device 100 will be described. First, the assembly frame 90 is fixed at a predetermined position of the water channel 10 . Next, positioning pins of the mounting frame 90 are fitted into positioning holes provided in the sieve device 40 to perform positioning of the sieve device 40 . In addition, the wedge liners 36 to 38 of the pulverizer 30 are suspended from above so as to face the wedge liners 91 to 93 of the mounting frame 90 to position the pulverizer 30 . In this way, the pulverizer 30 and the sieve device 40 are installed at predetermined positions of the assembly frame 90 , and the inclusion processing device 100 is installed in the water channel 10 . Alternatively, after fixing the sieve device 40 and the pulverizer 30 to the mounting frame 90 , the mounting frame 90 may be suspended and installed in the water channel 10 .

In the inclusion processing device 100 constructed in this way, the rotary crushing blades 32, 32 of the pulverizer 30 are driven by a vertical motor. The rotating crushing blade 32 on the side of the wall 10c (the right side in the figure) rotates counterclockwise. In addition, the vertical motor 48 drives the rake shaft 47 of the sieve device 40 , so that the water flow guide plate 50 and the rake 46 rotate rightward in plan view. Furthermore, the rotational speed of the tip of the rake 46 is equal to or less than 70% of the rotational speed of the outer circumference of the rotating pulverizing blades 32 , 32 . In addition, since the pulverizer 30 and the sieve device 40 each have a vertical motor, the biting and turning operation at the time of overload can be performed by the pulverizer 30 and the sieve device 40 respectively.

Here, the rake shaft 47 is arranged to be eccentric with the center 45o of the arc-shaped sieve member 45, so that the front end of the rake 46 appears from the front left side of the outer peripheral edge of the arc-shaped sieve member 45 to the outside in a plan view. The front side and the right side of the outer peripheral edge of the arc-shaped sieve part 45 pass through the outside of the arc-shaped sieve part 45, and are submerged in the arc-shaped sieve part 45 at the rear side of the right side of the outer peripheral edge of the arc-shaped sieve part 45 . In addition, the impurities in the water to be treated are collected by the arc-shaped sieve member 45 of the sieve device 40, and the impurities collected by the arc-shaped sieve member 45 pass through the front end of the rake 46 protruding from the outer peripheral edge of the arc-shaped sieve member 45. The inclusions are raked up and conveyed to shredder 30 . In addition, the water flow guide plate 50 rotates together with the rake shaft 47 to form the flow of the water to be treated toward the pulverizer 30 between the position where the rotating rake points to the position before the pulverizer and the position that points to the pulverizer. Therefore, it is easy to The collected inclusions are peeled off from the outer peripheral edge of the arc-shaped sieve member 45 and easily conveyed to the pulverizer 30 .

In this way, through the inclusion processing device 100, the inclusions will not stay or get stuck on the arc-shaped sieve member 45, the water flow resistance can be reduced, the water to be treated can flow smoothly, and the inclusions can be reliably collected into the pulverizer 30. . In addition, since the rear side of the arc-shaped sieve member 45 is opened, it is possible to prevent foreign matter from stagnating in the arc-shaped sieve member 45 and preventing the operation from being hindered. In addition, since the water flow resistance is reduced, the stress on the sieve device 40 can be reduced, and the durability of the sieve device 40 can be improved. In addition, the outer peripheral edge of the orbit of the rotary crushing blade 32 is close to the outer peripheral edge of the arc-shaped sieve member 45, and in its vicinity, the front end of the rake 46 is submerged from the outer peripheral edge of the arc-shaped sieve member 45. It is possible to efficiently and reliably collect foreign matter into the pulverizer 30 by reducing the amount of foreign matter that flows downstream from between the pulverizer 30 and the sieve device 40 . In addition, since the sieve device 40 has the water flow guide plate 50, the collected foreign matter can be easily peeled off from the outer peripheral edge of the arc-shaped sieve member 45, and the foreign matter can be collected into the pulverizer 30 more efficiently and reliably.

In addition, the rotation speed of the front end of the rake 46 is less than or equal to 70% of the rotation speed of the outer periphery of the rotating crushing blade 32, therefore, the inclusions picked up by the rake 46 are easily introduced into the pulverizer 30, and the inclusions can be more effectively and reliably Collected in the pulverizer 30. In addition, this was confirmed by the inventors of the present invention through experiments.

In addition, since the rake 46 is made of an elastic body, the rake 46 can be properly elastically deformed when foreign matter such as hard wood is interposed between the rake 46 and the shredder 30 , so that the rake 46 is not damaged.

In addition, the water flow guide plates 50 are arranged at equal intervals in the circumferential direction. Therefore, although a resistance against the water flow and hindering the rotation acts on one rake (a group of rakes arranged in parallel in the vertical direction) 46 in the circumferential direction, it is located at one rake. On the other rake 46 on the opposite side of the rake 46, the force that is promoted by the water flow acts on the other rake 46, which can properly disperse the water flow resistance of each rake 46, so that the rotational power of the rake shaft 47 can be suppressed and energy saving can be realized. Moreover, the rakes (groups of rakes arranged side by side in the vertical direction) 46 are not limited to being arranged in 4 equal divisions in the circumferential direction, but may also be arranged in 2 equal divisions, 3 equal divisions, or even greater than or equal to 5 equal divisions.

In addition, the vertical interval of each arc-shaped sieve member 45 is t (t=16), and the distance x (x=7) between the outer peripheral edge of the orbit of the rotary crushing blade 32 and the outer peripheral edge of the arc-shaped sieve member 45 Satisfies the relationship of 3 ≤ x ≤ t (unit: mm), and inclusions of a size that is not a problem even if they flow out from the downstream side pass between the sieve device 40 and the pulverizer 30, and inclusions of a size that are not expected to flow out from the downstream side It cannot pass between the sieve device 40 and the pulverizer 30 , but is transported to the pulverizer 30 , and can be screened according to the size of the inclusions, and the inclusions can be collected into the pulverizer 30 efficiently and reliably. Furthermore, in consideration of manufacturing errors and the like, the distance between the outer peripheral edge of the orbit of the rotary pulverizing blade 32 and the outer peripheral edge of the arc-shaped sieve member 45 must be greater than or equal to 3 mm.

In addition, since the arc-shaped sieve member 45 is formed of plastic, weight reduction and deformation can be reduced.

In addition, it can also be applied to a device having a structure in which a flat scraper is provided extending in the vertical direction between the sieve device 40 and the pulverizer 30, and the area between the sieve device 40 and the pulverizer 30 , The flow to the rear is thus blocked, and the flow of the water to be treated between the sieve device 40 and the pulverizer 30 is directed toward the pulverizer 30 . In this case, the foreign matter can be prevented from flowing out to the downstream side from between the sieve device 40 and the pulverizer 30 , and the foreign matter can be efficiently and reliably collected into the pulverizer 30 .

Claims (5)

1. an impurity treating apparatus is arranged side by side the screen device of collecting the field trash in the processed water into transversal water channel with the mill of pulverizing the field trash of being collected by this screen device, it is characterized in that,

Above-mentioned screen device and above-mentioned mill closely are provided with mutually,

Above-mentioned screen device has:

On above-below direction, be spaced from each other and stacked a plurality of circular-arc screen section;

Be spaced from each other setting on the above-below direction and mobile a plurality of rakes between above-mentioned stacked circular-arc screen section;

The rake axle that supports these rakes and extend along the vertical direction; And,

Current deflecting portion, with the common rotation of this rake axle, the position before the above-mentioned rake from rotation points to mill is to the position of pointing to above-mentioned mill, can form flowing towards the processed water of mill;

Above-mentioned mill has:

With upper and lower to being axle center rotation and the cutting edge that can pulverize field trash;

Above-mentioned rake axle is arranged to the center off-centre with the neighboring of above-mentioned circular-arc screen section, thus, the leading section of above-mentioned rake haunts from the neighboring of above-mentioned circular-arc screen section, the field trash of being collected by this circular-arc screen section can be harrowed to hold together to collect in the above-mentioned mill.

2. impurity treating apparatus as claimed in claim 1, it is characterized in that, the neighboring of the swing-around trajectory of above-mentioned cutting edge and the neighboring of above-mentioned circular-arc screen section are approaching, and the leading section of above-mentioned rake submerges near approaching position, the neighboring of the swing-around trajectory of the neighboring of above-mentioned circular-arc screen section and above-mentioned cutting edge.

3. impurity treating apparatus as claimed in claim 1 or 2 is characterized in that: the rotating speed of the front end of above-mentioned rake is smaller or equal to 70% of the rotating speed of the periphery of above-mentioned cutting edge.

4. impurity treating apparatus as claimed in claim 1 is characterized in that above-mentioned rake is made of elastic body.

5. impurity treating apparatus as claimed in claim 1 is characterized in that, the uniformly-spaced setting in a circumferential direction of above-mentioned current deflecting portion.

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