the apparatus according to fig1 for processing synthetic plastics material comprises a receptacle 1 which is tightly closed to below by a bottom 2 . in the region of the bottom a comminuting and mixing tool 3 is disposed for rotation around a vertical axis 4 , which tool is driven via a shaft 5 by a motor 6 disposed within a hollow space below the bottom 2 . at the level of this comminuting and mixing tool 3 an opening 8 is provided in the side wall 7 of the receptacle 1 , to which opening the housing 9 of a screw - type extruder 10 is connected . within the housing 9 an extruder screw 11 is beared for rotation , which screw is driven via a shaft 12 and a v - belt gearing 13 by a motor 14 . the material to be comminuted is introduced into the receptacle 1 through a charging hopper 15 and is comminuted and mixed by the rotating tool 3 and is forced by this tool into the opening 8 where the comminuted material is grasped by the screw 11 an is pressed out through an exit opening 16 leading from the housing 9 laterally . the inner diameter of the housing 9 of the screw - type extruder 10 may have equal diameter over its total length , however , it may also be enlarged like a funnel in the region of its end neighbouring the intake opening 8 ( fig2 ), this facilitating introducing of the material . in this case also the screw 11 is conically enlarged in this section . the core diameter of the screw may be equal everywhere , however , it is also possible , as fig1 shows , to vary this core diameter between the single threads of the screw , suitably enlarged stepwisely in direction towards the exit opening 16 in order to increase the pressure exerted onto the material to be extruded through the exit opening 16 . neither the housing 9 of the screw - type extruder 10 nor its screw 11 protrude from the inner wall of the receptacle 1 into its interior so that the circulation of the tool 3 is not hindered and no dead corners are formed . it is suitable to make the housing 9 and the front end of the screw 11 flush with the contour of the inner wall of the receptacle 1 , however , its is also possible to slightly offset the front of the screw 11 relative to this contour . the axis 17 of the screw - type extruder 10 or its thought extension , respectively , does not extend radially with respect to the axis 18 of the receptacle 1 ( which axis coincides with the axis 4 of rotation of the tool 3 in the working position shown in fig1 ), but is laterally offset relative to this radial direction 19 ( fig2 ), and this in the sense opposite to the moving direction of the comminuting and mixing tool 3 passing by the opening 8 , the sense of circulation of this tool 3 being indicated by an arrow 20 . this lateral offset is designated in fig2 and 3 by v . this offset has as a consequence that the component s ( fig2 ) of the peripheral force u exerted by the rotating tool 3 and acting in axial direction of the screw 11 is increased in comparison to an embodiment in which the axis 17 of the screw ( fig2 ) coincides with the said radial direction 19 . in this connection , the peripheral force u is measured in that point in which the axis 17 of the screw meets the circular periphery of the receptacle 1 , thus in the inlet opening 8 of the screw - type extruder . the amount of this offset v is about between 5 and 35 , preferably between 15 and 25 % of the radius of the receptacle 1 , which corresponds to an angle - measured offset with respect to the radial direction 19 of about 5 to 20 , preferably about 10 ° to 15 ° ( measured opposite to the direction of arrow 20 ). in order to assist pressing in of the synthetic plastics material comminuted by the rotating tool 3 into the screw - type extruder 10 it is further suitable to dispose the axis 4 around which this tool 3 circulates , eccentrically with respect to the axis 18 of the receptacle 1 , and this in direction towards the intake opening 8 of the screw - type extruder 10 . this eccentricity is designated in fig3 by e . by this eccentricity it is achieved ( see fig4 ), that that area f 1 ( fig5 ) or f 2 ( fig4 ), respectively , which lies between the side wall of the receptacle 1 and the periphery of the rotating comminuting and mixing tool 3 , in the region of the inlet opening 8 of the screw - type extruder 10 is substantially smaller ( area f 2 , fig4 ) than at the opposing side of the receptacle 1 ( area f 1 , fig5 ). the pressure acting on the comminuted synthetic plastics material , therefore , increases during the circulation movement of the comminuting and mixing tool 3 , starting from that side of the receptacle 1 situated opposite the intake opening , until this pressure in the region of the intake opening 8 reaches a maximum . during the second half of the circulation movement this pressure decreases again and reaches a minimum at the starting point , that means at that place of the receptacle 1 which is most far from the inlet opening 8 . the ratio f 1 : f 2 is suitably about 1 . 3 to 2 , in dependence from the compressibility of the synthetic plastics material to be processed . the amount of the eccentricity e can easily be calculated on this ratio if the profile of the comminuting and mixing tool 3 and of the receptacle 1 , respectively , is known . since the kind of the material to be processed or its compressibility are not always pre - known or do not remain constant , respectively , it is of advantage to make the amount of the eccentricity e variable or adjustable . as fig1 shows , for this purpose the shaft 5 of the comminuting and mixing tool 3 is displacable along a straight line 24 ( fig3 ) connecting the axis 18 of the receptacle 1 with the center point 22 ( fig3 ) of the ground plane of the inlet opening 8 . for this purpose , the shaft 5 is slidably guided in a longitudinal slot 23 ( fig1 ) in the bottom 2 of the receptacle 1 , the longitudinal axis of this longitudinal slot 23 lies on the mentioned straight line 24 ( fig3 ) connecting the axis 18 with the center point 22 . for fixing the position of the shaft 5 in the longitudinal slot 23 there is provided a ring 25 surrounding the shaft 5 , which ring is connected to a spindle 26 which can be rotated by means of a handwheel 27 which can be actuated from the outer side of the side wall 7 of the receptacle 1 . a rotation of the spindle 26 causes a shift of the ring 25 and thus of the shaft 5 in the longitudinal slot 23 . in order to avoid that material to be comminuted escapes downwardly from the receptacle 1 through those portions of the longitudinal slot 23 which are not filled by the shaft 5 , the ring 25 can be dimensioned correspondingly large or a sufficient big cover plate ( not shown ) can be connected to the shaft 5 above the slot 23 , which cover plate covers the remaining sections of the longitudinal slot 23 . within the embodiment according to fig2 to 5 the comminuting and mixing tool 3 is formed by a substantially circular carrier disk 28 circulating around the axis 4 , on which disk knives 29 are fixed which are only indicated in fig4 and 5 . however , it is more favourable to provide the carrier disk 28 with radial arms 30 carrying the knives 29 . as fig6 shows , the working edges 31 of the knives 29 are formed according to an angle so that the free ends of these working edges 31 are backwardly offset , when seen in direction of rotation of the tool 3 . thereby a spatula - like action on the comminuted material is achieved which assists to press in this material in the region of the inlet opening 8 into the screw - type extruder 10 .