DE3814458A1 - Air separator - Google Patents

Abstract

The invention relates to an air separator in which at least one separator rotor which rotates about a horizontal axis of rotation is arranged in a separator housing and in which a mixture of separator air and fine material is fed to the outer peripheral region of the separator rotor via a feed channel. In this arrangement, the feed channel opens approximately tangentially into the separator housing, and provided in the outer peripheral region of the rotor is a vane ring, in the lower peripheral section of which - in the vicinity of the opening point of the feed channel - a cutting edge for coarse material is arranged. The said air separator ensures a high throughput capacity together with a precise and adjustable cut point.

Description

The invention relates to a wind sifter for separation dry fine-grained to dusty Visual goods in coarse and fine material fractions, according to the preamble of claim 1.

A large area of application of wind classifiers is the separation of shredded material in the stone and earth industry (especially in the manufac cement) as well as in ore processing and the like. There is mostly wind here today classifier with vertical rotor axis in use. The increasing throughput rates correspondingly larger dimensions changing viewing conditions. For these reasons you keep trying to windsifter with horizon to construct valley-axis classifying rotors, whereby a number of problems here too, for example with regard to a sharp separation limit, desired throughput rates and setting options, occurred.

For example, there is also a wind sifter of the kind assumed (DE-OS 36 15 494) with which, among other things, a higher one Throughput performance with possibly several grain fractions tion is to be achieved in that he essentially has a rectangular housing, in which several horizontal-axis, parallel next to stacked and / or stacked classifiers rotors are arranged. This arrangement of Classifying rotors become the classifying air / classifying material mixture through at least one from below into the classifier housing and largely approximately radial to the classifier  rotors infeed tube supplied, which is far below the un the first classifying rotor opens. From everyone terrotor is supposed to have a certain fine material fraction are suctioned off, each in the direction of flow because rear classifier rotors have a larger separation should have sharpness as front. For one out sufficiently high throughput must accordingly a large number of classifying rotors see and thus also a relatively large construction effort operate.

The invention has for its object a Air classifier in the preamble of claim 1 presupposed kind of creating that at relative simple construction a relatively sharp Fe separation limit even with a relatively high throughput performance enables. In addition, the Possibility to be created this wind sifter with essentially the same basic construction tion for large and large throughputs adapt.

This object is achieved by the im Characteristics of claim 1 specified features solved, meaningful configurations and Wei Further training is the subject of the subclaims.

By supplying the classifying air Visible material mixture approximately tangential to the outer circumference area of the classifier rotor can be extremely good and even distribution of what is to be separated Visible good both about the scope and about reach the length of the classifier rotor. these are already very good conditions for an equal  moderate load on the entire classifier rotor and thus both for a sharp separation limit as also for high throughput.

The selectivity of the individual good fractions (fine good and coarse goods fractions) is through the Vorse hen a vane ring in the outer circumference range of the classifier rotor further optimized where also contributes to a coarse material cutting, which leads to the Ab loosen an inner material ring from the outer circumference of the classifier rotor and in the lower (lower ge )) circumferential section of the guide vane ring as well as near the junction of the feeder channel is arranged.

This air classifier according to the invention can already in a version with a single rotor and a single outlet duct for the air fine material Mix a relatively high throughput pass. Selectivity and throughput read change by changing the main classifier rotor measurements, d. H. of the diameter sers and the length as well as the ratio of Adjust diameter to length, within wide limits, where the separation limit largely depends on the diameter depends on the classifier rotor, d. H. the finer the pro product should be, the smaller it expediently becomes the rotor diameter selected.

With the basic construction of the wind sifter according to the invention now results Possibility with the same main dimensions the classifier rotor, d. H. with a constant view conditions to thereby increase the throughput increase that the classifier rotor (and in adaptation  that of course also includes this sifter rotor surrounding classifier housing) ver multiple times by - according to claim 2 - the classifier rotor in two coaxial mutually lying, equally long rotor longitudinal sections cuts divided and / or - according to claim 5 - two of the same kind and of the same size Terrotors parallel to the axis in the common sighting rim arranges housing, with all classifying rotors or Ro longitudinal gate sections then each have the same diameter ser: have length ratio. Compared to the basic construction of the first described Air classifier with one, undivided classifier rotor then receives the air classifier accordingly Execution with one split sifter rotor double the throughput and a wind safety version with two subdivided in length Classifier rotors four times the throughput of the Basic construction.

The invention is based on some in the following the drawing illustrated exemplary embodiment le described in more detail. In the largely schematic show the drawing

Figure 1 is a longitudinal sectional view through a first embodiment of the air classifier, ie through a basic construction with only one, undivided classifier rotor.

Fig. 2 is a cross-sectional view taken approximately along the line II-II in Fig. 1;

Figure 3 is a longitudinal sectional view through a second embodiment of the air classifier, with a divided in the longitudinal center terrotor.

Fig. 4 and 5 cross-sectional views through two different embodiments of the air classifier, each with two par allel lying side by side rotors in a common Sich tergehäuse;

Fig. 6 and 7 two different, partially hori zontal cut Grundrißansich th of air classifier designs with two horizontally side by side the classifier rotors, with various NEN arrangement options for fine separators;

Fig. 8 and 9 cross-sectional views of two wind sifter examples with different ways to initiate Se secondary air;

Fig. 10 is a cross-sectional view of a white direct embodiment with an injector for the task of sighting in the feed channel;

Fig. 11 is a cross-sectional view of the wind sifter, in the feed channel of which a deflector is installed;

Fig. 12 is a further simplified overall view of an embodiment in which the air classifier is constructed in the form of a circulating air classifier.

A basic version of the wind sifter according to the invention with its parts primarily of interest here will first be explained with reference to FIGS . 1 and 2. In the exemplary embodiment illustrated here, the air classifier contains a classifier housing 1 , to which a feed channel 2 for a classifying air-classifying material mixture (cf. continuous classifying air arrows 3 and dashed classifying arrows 4 ) is connected and in its lower section a coarse material collecting funnel 5 has. In the interior of the classifier housing 1 , a preferably cylindrical and horizontally arranged classifier rotor 6 is provided in this example, which has a horizontal rotary shaft 7 forming an axis of rotation. About this rotary shaft 7 , the sifting rotor 6 is rotatably supported in bearings 8 arranged outside half of the sifter housing 1 . The rotary shaft 7 can be driven in a usual manner by a drive motor 9 - if appropriate with a variable speed - so that the rotor 6 can be driven in the direction of the arrow 10 ( FIG. 2).

The classifying rotor 6 can be occupied in a manner known per se on its circumference with sight strips 11 , which have the same circumferential spacing from one another and, depending on the design and application of the wind classifier, are arranged fixedly or in their angular position.

In the outer circumferential area of the classifying rotor 6 , a classifying vane ring 12 surrounding this classifying rotor is provided, the individual leading blades 12 a of which are arranged coaxially around the classifying rotor 6 on an imaginary circle and are preferably adjustable jointly about pivot axes 12 b , which are parallel to the rotary shaft 7 run.

The feed channel 2 for the classifying air classifying material mixture (arrows 3 and 4 ) opens out approximately tangentially to the outer peripheral region of the classifying rotor 6 into the classifying housing 1 , as is shown in FIG. 2. This mixture of classifying air and classifying material (arrows 3 , 4 ) can thus be fed to the classifying rotor 6 from its outer circumference - via the guide vane ring 12 - in a uniformly distributed manner. During this feeding, the coarse material to be separated then falls out downwards or is ejected downwards and collected there in the coarse material collecting funnel 5 (and discharged from there accordingly). In contrast, the fine material contained in the mixture supplied is passed together with the classifying air flow (arrows 3 ) into the interior space 6 a of the classifying rotor 6 . This inner space 6 a is now in the present example on the one rotor end 6 b with an outlet channel 13 for the air-fine material mixture, which in turn is connected to a fine material separating device, not shown here, which is about a cyclone separator, a fine material separation filter or the like.

With this horizontal arrangement of the sifting rotor 6 , it is also advantageous for reliable operation and good selectivity if a coarse material cutter 14 is arranged in the lower peripheral section of the guide vane ring 12 , that is to say approximately in the region of its lowest point, and in the vicinity of the junction point of the feed channel 2 is, as can be seen in the cross-sectional view of FIG. 2. This coarse material cutting edge 14 extends - just like the guide vane ring 12 - parallel to the Sichterro gate 6 and over its entire length. By means of this coarse material cutting edge, a material ring possibly formed in the area of the outer circumferential side of the rotor can be detached from coarse material and also fed to the coarse material hopper 5 .

While in the previously explained with reference to FIGS . 1 and 2 he basic construction of the air classifier the classifier rotor 6 is undivided in length and has only one outlet end 13 for the air / fine material mixture, the classifier can be of essentially the same construction rotor 6 can also be divided in length. Such an embodiment is illustrated in FIG. 3. Thereafter, the rotor 6 of the Windsich age in a first version on its longitudinal center by a partition 15 into two coaxial, equally long rotor longitudinal sections 6 ₁ and 6 _{2 can be} divided, of course, the sifter housing 1 is fitted accordingly . In this embodiment, in turn, a common feed channel 2 for the classifying air-class mixture - provided in the same way as in FIG. 2 - can be provided. Here, however, the interior of each longitudinal rotor section 6 ₁ and 6 _{2 is} connected via the respective outer rotor end face 6 b ₁ , 6 b ₂ to a separate outlet duct 13 ₁ and 13 ₂ for the corresponding mixture of air and fine material. Furthermore, in this first version of the classifying rotor 6 divided in its longitudinal center, this self-rotor 6 can otherwise be designed as a continuous rotor unit with a common rotary shaft 7 for the rotor longitudinal sections 6 ₁ , 6 ₂ , for which purpose only a single drive motor 9 for the rotary drive of the rotor is required.

A second version of this previously schil based on Fig. 3 and divided in its longitudinal center sifter rotor 6 is possible in that the two equally large Ro longitudinal sections 6 ₁ and 6 ₂ with separately mounted, independently drivable rotary shafts 7 ₁ and 7 ₂ are, each rotary shaft 7 ₁ , 7 _{2 is assigned} a special drive motor 9 or 9 ₂ . As indicated in phantom in Fig. 3, thereby, the rotational shaft 7 ₁ as a hollow shaft and the other Drehwel le 7 ₂ may be formed as a continuous shaft, both rotary shafts can then zen mutually stock different bearing, as known per se. This training offers the possibility, inter alia, of driving the two longitudinal rotor sections 6 ₁ and 6 ₂ at different speeds and thereby possibly also making the separating limits in the region of these two rotor longitudinal sections differently, so that different fines fractions are brought about.

With regard to this longitudinal subdivision of the classifying rotor 6 explained with reference to FIG. 3, it should also be noted that, of course, the guide vane ring 12 and the associated coarse material cutting edge ( 14 in FIG. 2) are provided and adapted accordingly. Furthermore, this embodiment offers itself with the longitudinal subdivision of the classifying rotor if an increase in throughput compared to an embodiment according to FIGS. 1 and 2 is to be achieved, ie if, for example, each longitudinal rotor section 6 ₁ and 6 _{2 is the} same size as the rotor 6 in Fig. 1, then with the help of the terausführung according to FIG 3, a doubling of the throughput can be achieved. Of course, adapted intermediate sizes are also possible, in particular due to changes in length. A further increase in the throughput can be achieved with this inventive air classifier with the same good selectivity since two identically and equally sized classifier rotors 6 are arranged axially parallel in the common classifier housing 1 , as described below using two further examples according to FIGS . is explained in more detail 4 and 5. In the exemplary embodiments described below (FIGS . 4 and 5), it is common that the two classifying rotors 6 et wa are arranged horizontally next to one another and in the same manner as previously described with reference to FIGS . 1 and 2 with guide vane rings 12 and coarse material cutting edges 14 arranged thereon are equipped. These two classifier rotors 6 with their associated parts can in principle be designed as single, undivided rotors, as described with reference to FIGS . 1 and 2, or as rotors divided in the longitudinal center thereof, but for a sensible increase in throughput with appropriate construction and design effort two sifter rotors 6 divided into their longitudinal center, as described with reference to FIG. 3, are to be provided, so that in the latter case compared to the embodiment according to FIG. 1 - with the same diameter: length ratio of the individual rotors or longitudinal sections of the rotor, a quadrupling the throughput can be achieved. Both in Ausführungsbei Fig. 4 wherein the pivot shafts 7 play according as well as in the FIG. 5 1 can be regard to the design and arrangement of the rotors and largely also the classifier in a sense of a doubling compared to Fig. And Fig. 3 talk, both Classifier rotors 6 are each preferably arranged in the same horizontal plane and with sufficient spacing from one another, so that then at classifier rotors 6 can work unaffected from one another.

In the embodiment of Fig. 4 is provided a common supply channel for both Sichterrotoren 6 2 for the sifting material and classifying air mixture (arrows 3 and 4), the gates between these two Sichterro 6 tangential to its adjacent to each other the outer peripheral portions in the classifier 1 opens. The two classifier rotors 6 are driven in opposite directions (see arrows 10 ), in which - considering their upper halves - both rotate outwards. In this design of the air classifier with a common feed channel 2 , it is then necessary to provide a separate coarse material collecting funnel 5 ₁ or 5 ₂ in the area below each classifier rotor 6 .

In the Sichterausführung of FIG. 5 demge a separate feed channel 2 is ₁ or 2 ₂ assigned for the classifying air-sifting material mixture genüber each separator rotor. 6 These two feed channels 2 ₁ , 2 ₂ are connected tangentially to it on approximately opposite outer sides of the classifier housing 1 , as can be clearly seen from FIG. 5. In this design can also be seen from both classifier rotors 6 then a common coarse material hopper 5 before, at the lower end of which a material collecting screw 16 or another suitable conveyor can preferably be installed.

All other parts can in this embodiment examples of FIGS. 4 and 5 otherwise - as he thinks - be of the same design and arrangement, as has been described above.

As has already been indicated above, each outlet channel 13 for the air / fine material mixture can be connected to a suitable fine material separating device. FIGS. 6 and 7 now illustrate some embodiments and types of coordination of the fine material separator means, it being assumed that it is in the illustrated here air classifier designs to those described with reference to above FIG. 4 and 5. wor are the , ie air classifier designs each with two similar classifier rotors 6 , which are also divided accordingly in accordance with the example of FIG. 3 in their longitudinal center and thus each have two longitudinal rotor sections 6 ₁ and 6 ₂ . Both in the example of FIG. 6 and in the example of FIG. 7, the interior of each longitudinal rotor section 6 ₁ , 6 _{2 is} via a separate outlet duct 13 ₁ or 13 ₂ for the corresponding air / fine material mixture with a separate fine material Separation cyclone 17 ₁ or 17 ₂ connected.

While in the embodiment according to FIG. 6 the four separating cyclones 17 ₁ and 17 ₂ - viewed in the layout of the wind sifter - are arranged approximately in the outer corners of a rectangle giving the entire air sifter, ie one is in each corner of this imaginary rectangle Arranged from separating cyclone, in the exemplary embodiment according to FIG. 7, the four separating cyclones 17 ₁ and 17 _{2 are arranged} in a common vertical plane - with respect to their vertical axes - on a bottom side of the separator. In the last-mentioned example ( FIG. 7), this results in a particularly compact design for the fine material separation decyclone.

With reference to FIGS . 8 and 9, two implementation options are described below as to how secondary air can additionally be introduced into the outer peripheral region around the classifying rotor or the classifying rotors. The secondary air can, depending on the need, be additional visual air, cooling air or hot drying air for the good view.

According to the embodiment shown in FIG. 8, a secondary air inlet connection 18 is also connected approximately tangentially to the classifier housing 1 in the tangential junction area of the feed channel 2 for the classifying mixture of fine air and fine material to the outer circumferential area of the classifying rotor 6 , so that secondary air (arrows 19 ) in a circumferential area of about 180 ° from outside the guide vane ring 12 into the outer circumferential area of the sifting rotor 6 can be introduced (of course approximately over the entire length of the sifting rotor). It can also be particularly advantageous if, as shown in FIG. 8, a guide vane apparatus 21 with individual guide vanes 21 a is arranged in the region of the tangential orifice 20 of the secondary air inlet connection 18 , which are preferably adjustable, by being about their pivot axes 21 b can be pivoted together in one or the other direction. As a result, the secondary air supply and distribution can be controlled particularly well.

In the exemplary embodiment of FIG. 9, in contrast to FIG. 8, two secondary air inlet connections 18 ₁ and 18 _{2 are} connected tangentially to the classifier housing in the tangential junction area of the feed channel 2 to the outer circumferential area of the self-rotor 6 . In a sol chen arrangement of a plurality of secondary air infeed connection 18 _1, 18 ₂ can be run under a down specific guide vane (as indicated at 21 in Fig. 8) are omitted, characterized sufficient circumferential distribution of the supplied secondary air is ensured.

Any suitable device known from practice can be used for feeding the material to be separated into the feed channel. A particularly simple embodiment is shown in FIG. 10, according to which the feed channel 2 for the visual air / visual material mixture has an injector 22 or a corresponding de injector-like design at its end located away from the classifier housing 1 . This injector 22 has an axial sight air inlet opening 23 and a sight feed port 24 connected to the narrowest injector point on the circumference.

Although a preferred arrangement of the guide channel 2 for the classifying air / classifying material mixture is illustrated in FIG. 10, in that this supply channel 2 runs vertically rising (and accordingly the associated injector 22 ), it can also be horizontal or inclined if necessary ter course of supply channel 2 and / or injector 22 may be provided.

Preferably, in the case of an approximately vertically increasing course of the feed channel 2 for the classifying air-visual mixture, a further embodiment of the air classifier can be provided in the manner as illustrated in FIG. 11. Then in this feed channel 2 - preferably in the area of his lower end distant from the classifier housing 1 - as coarse material caution level, an additional order sifter 24 is installed, which has a simple deflection chamber 25 for the air-visual material mixture flowing through it (arrows 3 and 4 ) contains. In this diversion chamber 25, a regu lierbare adjusting flap 26 is preferably installed to pivot about an at Sichterdeckwand 24 a pivot axis arranged 26 a in the direction of the double arrow 7 who can the, thereby to by a lower duct portion 2 a rising sifter air-Sichtgut- Ge mixed flow inside the chamber 25 first downward and then upward again (as indicated in Fig. 11 by arrows 3 and 4 ), so that coarse coarse material (arrow 28 ) can fall down in the desired, adjustable manner. Finally, FIG. 12 shows, in a simplified schematic representation, an overall arrangement of the air classifier if it is constructed in the form of a circulating air classifier. In this Fig. 12 it can be seen that the circulating air classifier in turn a classifier housing 1 , an ascending, tangentially connected to guide channel 2 for the classifying air-classifying material mixture, a classifying rotor 6 arranged within the classifier housing with associated guide vane ring 12 (and not shown, associated coarse gutschneide), further includes an outlet duct 13 for the air-fine material mixture and a duct 13 connected to this outlet fine material separating cyclone 17 . Further, a the sifting air stream erzeu gender convection fan 29 is provided, the suction side through a suction line 30 to the deposition cyclone 17 and the pressure side via an air line as the view serving pressure line 31 communicates with the feed channel 2 in connection.

In this embodiment of the circulating air classifier, an injector 22 is arranged at the lower end of the approximately vertical rise of the feed channel 2 , as is illustrated and described with reference to FIG. 10 and in the circumference of a visible material task 24 cut obliquely from above flows into. A collecting device 32 for very coarse coarse material is connected to the supply duct 2 below this connection point of the visible material feed nozzle 24 , that is to say below the injector 24 (or in the jector-like configuration of the supply duct 2 ). This collecting device 32 is arranged in the area below the feed duct section 24 containing the material to be fed, preferably arranged directly below the injector 22 , and the pressure line 31 coming from the circulating air fan 29 and leading to the classifying air opens into the upper end of this collecting device 32 . From the injector 22 possibly falling down very coarse coarse material can be seen from the inflow from the pressure line 31 the sight air (arrow 3 ), so that in the coarse material collecting device 32 actually only very coarse material fails downwards. This collecting device 32 can be extremely simple gestal tet, for example - as shown in Fig. 12 Darge - by an enlarged cross-section Kam mer with arranged below the collecting hopper.

It goes without saying that even in this embodiment as a circulating air classifier ( Fig. 12) each of the previously described embodiments of Sich tergehäuse and classifier rotor can be used.

Furthermore, each of the embodiments of the air classifier described with reference to FIGS. 1 to 9 and 11 can also be used - as opposed to the somewhat autonomous order air air classifier according to FIG. 12 - as a type of air classifier in which no own air system and no own air system Visual goods are available. Such flow classifiers are preferably connected to, or integrated into, the outflow lines from airflow mills, classifier grinding plants, etc., which contain a fine material / air mixture.

Claims (13)

1. Air classifier for separating a dry, fine-grained to dusty material in coarse and fine material fractions

• a) a classifier housing ( 1 ), to which at least one feed channel ( 2 ) for a classifying air-classifying material mixture ( 3 , 4 ) is connected and we at least one coarse material collecting funnel ( 5 ) as at least one with a fine material Ab separating device ( 17 ) connected outlet channel ( 13 ) for an air-fine material mixture,
• b) at least one revolving around a horizontal axis of rotation ( 7 ), on the circumference with sight strips ( 11 ), sifting rotor ( 6 ) to which the mixture of visible air and visible material is fed from the outer circumference and its interior ( 6 a ) via at least one The front end of the rotor ( 6 b ) is connected to the outlet channel ( 13 ) for the air / fine material mixture,

characterized by the combination with the following characteristics:

• c) the feed channel ( 2 ) for the classifying air / fine mixture ( 3 , 4 ) opens approximately tangentially to the outer peripheral region of the classifying rotor ( 6 ) into the classifier housing ( 1 );
• d) in the outer circumferential area of the classifying rotor ( 6 ) there is a classifying rotor ring ( 12 ) providing this classifying rotor at a distance;
• e) in the lower peripheral portion of the guide vane ring ( 12 ) and in the vicinity of the junction of the feed channel ( 2 ) a coarse material cutting edge ( 14 ) is arranged.

2. Air classifier according to claim 1, characterized in that the classifying rotor ( 6 ) in two ko axially lying, equally long rotor longitudinal sections ( 6 ₁ , 6 ₂ ) with a common feed channel ( 2 ) for the classifying air-classifying material mixture un divided and the interior of each rotor longitudinal section over the respective outer rotor end ( 6 b ₁ , 6 b ₂ ) with a separate outlet channel ( 13 ₁ , 13 ₂ ) for the corresponding air-fine mixture Connection is established. 3. Air classifier according to claim 2, characterized in that the classifying rotor ( 6 ) is divided on its longitudinal center by a partition ( 15 ) into which in the longitudinal sections ( 6 ₁ , 6 ₂ ) and these two longitudinal sections one on a common rotary shaft ( 7 ) Form a fixed rotor unit. 4. Air classifier according to claim 2, characterized in that the two rotor longitudinal sections of equal size ( 6 ₁ , 6 ₂ ) with separately stored th, independently driven rotary shafts ( 7 ₁ , 7 ₂ ) are provided. 5. Air classifier according to claim 1 or 2, characterized in that two identically and equally sized classifier rotors ( 6 ) are axially parallel in the common classifier housing ( 1 ) angeord net, both classifier rotors are driven in opposite directions fig. 6. Air classifier according to claim 5, characterized in that for both classifier rotors ( 6 ) a common feed channel ( 2 ) for the classifying air / classifying material mixture ( 3 , 4 ) is provided, between them tangent to their adjacent outer peripheral regions opens into the classifier housing ( 1 ), with each classifying rotor ( 6 ) having its own guide vane ring ( 12 ) with coarse cutting edge ( 14 ) and its own coarse material collecting funnel ( 5 ₁ , 5 ₂ ). 7. Air classifier according to claim 5, characterized in that each classifier rotor ( 6 ) is assigned its own feed channel ( 2 ₁ , 2 ₂ ) for the classifying air / classifying material mixture, these supply channels approximately on opposite sides of the classifier housing ( 1 ) are connected and a common coarse collecting funnel ( 5 ) is provided under both classifier rotors ( 6 ). 8. Air classifier according to claim 1, characterized in that in the tangential junction area of the feed channel ( 2 ) for the classifying air-view mixture well to the outer peripheral area of the classifier rotor ( 6 ) at least one secondary air inlet port ( 18 , 18 ₁ , 18 _2nd ) is also connected approximately tangentially to the classifier housing ( 1 ). 9. Air classifier according to claim 8, characterized in that in the region of the tangential orifice ( 20 ) of the secondary air inlet nozzle ( 18 ), an optionally with adjustable blades ( 21 a ) provided guide device ( 21 ) is arranged. 10. Air classifier according to claim 1, characterized in that the feed channel ( 2 ) for the view air-visual material mixture extends approximately vertically and in this feed channel in the area in front of the self-sealing housing ( 1 ) as a coarse material caution level to a steering classifier ( 24 ) is installed, which contains a simple deflection chamber ( 25 ) for the visible air / visible material mixture flowing through, preferably with an adjustable adjusting flap ( 26 ). 11. Air classifier according to claim 1, characterized in that the feed channel ( 2 ) for the visible air-visual material mixture at its end from the classifier housing ( 1 ) is an injector ( 22 ) with an axial visible air inflow opening ( 23 ) and a visible material feed nozzle ( 24 ). 12. Air classifier according to claim 1, wherein it is constructed in the form of a recirculating air classifier and a verbun with the air-fine material mixture outlet duct fines separating device ( 17 ), one with it and with the feed channel ( 2 ) for the classifying air Visible material mixture connected recirculation fan ( 29 ) and a visual goods feed connector ( 24 ) on the feed channel, characterized in that the visual goods feed connector ( 4 ) is formed on a preferably injector-like, approximately vertical section of the feed channel ( 2 ). provided and below the junction of this sight feed port ( 24 ) to the feed channel ( 2 ) a catch device ( 32 ) for very coarse coarse goods ( 28 ) is closed, the area below the sight feed neck ( 24 ) containing the feed channel section a view from the pressure side of the circulating air fan ( 29 ) coming air line ( 33 ) is connected.