METHOD AND COLLOIDAL MIXER FOR COLLOIDAL PROCESSING OF A SLURRY

Abstract

The invention relates to a method and a colloidal mixer for colloidal processing of a slurry, in particular processing of construction materials, with a colloidal mixer, in which at least one liquid is introduced into a mixing trough, at the lower region of which is arranged an outlet opening with a mixing device having a mixing rotor, which is driven in rotation.

According to the invention, the at least one pulverulent solid component is introduced into the mixing trough, the at least one liquid mixed with the at least one pulverulent solid component is induced to flow by the rotatingly driven mixing rotor and is discharged from the mixing trough through the outlet opening, wherein the mixture is led back again for a certain time via a backflow line into an upper region of the mixing trough for further mixing and, after a desired mixing state has been attained, the mixture is discharged as a finished slurry from the outlet opening by means of a discharge line.

According to the invention, it is provided that air is incorporated into the at least one liquid and/or the mixture in a targeted manner in a finely dispersed form, wherein a relative density of the liquid, or of the mixture, is reduced.

Claims

1. A method for the colloidal processing of a slurry, in particular processing of construction materials, using a colloidal mixer, in which at least one liquid is introduced into a mixing trough, at the lower region of which is arranged an outlet opening with a mixing device having a mixing rotor which is driven in rotation, at least one pulverulent solid component is introduced into the mixing trough, the at least one liquid is mixed with the at least one pulverulent solid component by means of the rotationally driven mixing rotor, is induced to flow, and is discharged from the mixing trough through the outlet opening, wherein the mixture is returned again for a certain time via a flowback line to an upper region of the mixing trough for further mixing, and after reaching a desired mixing state, the mixture is discharged as a finished slurry from the outlet opening by means of a discharge line, wherein air is incorporated into the at least one liquid and/or the mixture in finely dispersed form in a targeted manner, wherein a relative density of the liquid, or of the mixture, is reduced.

2. Method according to claim 1, wherein the relative density of the at least one liquid or the mixture is reduced, wherein the volume of the liquid or of the mixture is increased by 2 percent to 15 percent by supplying air.

3. Method according to claim 1, wherein the backflow line comprises a port opening which is directed towards an inner side of the mixing trough, wherein the led back liquid or mixture impinges on the inner side.

4. Method according to claim 3, wherein a backflow from the backflow line impinges approximately perpendicularly on the inner side of the mixing trough.

5. Method according to claim 3, wherein a backflow from the backflow line is essentially divided into two partial flows when it impinges on the inner side of the mixing trough, which partial flows flow in opposite directions along the inner side of the approximately drum-shaped mixing trough.

6. Method according to claim 5, wherein the two partial flows are generated with a flow velocity such that the partial flows meet, along with a formation of swirls, at a point of the mixing trough which is approximately opposite to the port opening.

7. Colloidal mixer for the colloidal processing of a slurry, in particular for the processing of construction materials and in particular for performing a method according to claim 1, comprising a mixing trough which comprises an upper feed opening for feeding at least one liquid and at least one pulverulent solid component and a lower outlet opening, a mixing device which comprises a mixing rotor which can be driven in rotation and is arranged in a lower region of the mixing trough, wherein the at least one liquid and the at least one pulverulent solid component are mixed by the mixing rotor into a mixture and a flow of the at least one liquid or of the mixture can be generated towards the outlet opening, a backflow line which extends from the outlet opening back again to the upper feed opening of the mixing trough, a discharge line for discharging a finished slurry from the mixing trough, and a control valve device by means of which the backflow line and the discharge line can be opened or closed, in particular alternately, wherein the colloidal mixer is configured to incorporate air in finely dispersed form into the at least one liquid, or the mixture, in a targeted manner in order to reduce a relative density of the liquid, or of the mixture.

8. Colloidal mixer according to claim 7, wherein the backflow line comprises a port opening which is directed towards an inner side of the mixing trough.

9. Colloidal mixer according to claim 7, wherein an air supply device comprising at least one supply nozzle is arranged for injecting air into the liquid or mixture.

10. Colloidal mixer according to claim 7, wherein in that the mixing rotor is arranged in a recess at the bottom of the mixing trough upstream the outlet opening.

11. Colloidal mixer according to claim 10, wherein in that the recess with the mixing rotor is arranged centrally or eccentrically on the bottom of the mixing trough relative to the center axis thereof.

12. Colloidal mixer according to claim 7, wherein a rotor axis of the mixing rotor and a center axis of the drum-shaped mixing trough are located in a center plane of the mixing trough and, in that a backflow from the port opening of the backflow line impinges on the inner side of the mixing trough approximately parallel to the center plane.

13. Colloidal mixer according to claim 7, wherein the mixing rotor comprises mixing blades which are provided with a hole pattern.

Description

[0057] The invention is described in greater detail below with reference to a preferred exemplary embodiment, which is shown schematically in the accompanying drawings. The drawings show in:

[0058] FIG. 1 a side view of a colloidal mixer according to the invention;

[0059] FIG. 2 a cross-sectional view through a colloidal mixer according to the invention according to FIG. 1;

[0060] FIG. 3 a top view of the colloidal mixer of FIG. 1, but without lid;

[0061] FIG. 4 an enlarged illustration of a mixing blade in a side view with a hole pattern;

[0062] FIG. 5 a frontal view of the sheet metal-type mixing blade of FIG. 4;

[0063] FIG. 6 an enlarged illustration of detail A of FIG. 4; and

[0064] FIG. 7 an enlarged illustration of detail B of FIG. 4.

[0065] FIGS. 1 to 3 show an exemplary embodiment of a colloidal mixer 10 according to the invention with a drum-shaped mixing trough 12, which is arranged on a frame 11. The drum-shaped mixing trough 12 has a cylindrical inner surface 13 or inner wall in its upper portion, and is closed at its upper surface by a lid 14. A lower portion of the mixing trough 12 is formed by a conically configured bottom 16, which merges via an opening into a downwardly directed receptacle or recess 20 with a mixing device 30. The opening having the recess 20 is arranged eccentrically to a center axis of the cylindrical upper section of the mixing trough 12, as can be seen clearly in FIG. 3.

[0066] The mixing device 30 in the recess 20 on the underside of the mixing trough 12 has a rotationally driven mixing rotor 32 with a rotor hub 33 and radially oriented mixing blades 34 attached thereto. Altogether, the mixing rotor 32 with the mixing blades 34 is configured such that at least one liquid component introduced into the mixing trough 12 is mixed with at least one pulverulent solid component supplied into the mixing trough 12 by means of the rotating mixing rotor 32. In this case, a circumferential speed of the mixing rotor 32 is set in such a way and the shape of the mixing blades 34 is designed in such a way that cavities are formed in a targeted manner in the at least one liquid or the mixture forming, which further support a mixing effect and a fine distribution of air.

[0067] The at least one liquid or the forming mixture is discharged by means of the rotationally driven mixing rotor 32 to a lateral outlet opening 22 with a Y-pipe section 24, at the two outlet connections of which a backflow line 40 on the one hand and a discharge line 50 on the other hand are arranged. An actuator 38 can be used to control whether the mixture formed is returned to the mixing trough 12 via the backflow line 40 for continuation of the mixing process or is discharged from the colloidal mixer 10 via the discharge line 50.

[0068] For forming the actuator 38, a first pinch valve 42 is arranged on the backflow line 40 and a second pinch valve 52 is arranged on the discharge line 50, which can be closed or opened in particular by supplying a pressure medium, in particular compressed air.

[0069] When the first pinch valve 42 is open and the second pinch valve 52 is closed, liquid or mixture is returned again from the Y-pipe section 24 to an upper portion of the mixing trough 12 via the backflow line 40 through a feed opening 15 in the lid 14, as illustrated clearly in FIGS. 2 and 3.

[0070] In this case, the free end of the backflow line 40 has a deflecting tube or port opening 44, which is directed towards the inner side 13 of the mixing trough 12. As a result of the of the liquid or mixture exiting the port opening 44 and impinging on the inner side 13 of the mixing trough 12, ambient air is finely dispersed incorporated in the liquid or mixture. This is supported by the fact that the backflow is divided into two partial flows by the orientation of the port opening 44, which flow along the inner side 13 of the mixing trough 12 in opposite directions in the circumferential direction. At a flow velocity of several meters per second, the partial flows can thus meet again in an opposite area on the inner side 13 of the mixing trough 12, wherein further air is incorporated into the liquid or mixture by additional swirl.

[0071] The incorporation and fine distribution of the air is further increased by the rotating motion of the mixing rotor 32 with the mixing blades 34, as already described above. The mixing process can preferably last between 100 seconds to 200 seconds.

[0072] Once a desired consistency or homogeneity of the mixture has been achieved, the first pinch valve 42 on the backflow line 40 can be closed and the second pinch valve 52 on the discharge line 50 can be opened. In this manner, the ready formed mixture or slurry is discharged from the colloidal mixer 10 through the discharge line 50 and out of the outlet opening 22 by the pumping action of the mixing device 30.

[0073] After emptying the mixing trough 12, another mixing process for a new batch can be started.

[0074] FIGS. 4 to 7 show a possible embodiment for a mixing blade 34, which can be used on a mixing rotor 32 of a mixing device 30 of the colloidal mixer 10 described above.

[0075] For fastening the mixing blade 34 to a rotor hub 33 of the mixing rotor 32, fastening elements 37 are shown schematically on one fastening side. These elements serve for detachable fastening of the mixing blade 34 to the rotor hub 33. FIG. 6 shows detail A with the fastening element 37 of FIG. 4 in greater detail.

[0076] The mixing blade 34 is formed from a base metal sheet 35 with a thickness d, as can clearly be discerned in FIG. 5. The thickness d can range from 3 mm to 20 mm. A hole pattern 36 having a plurality of through holes is formed in the actual mixing region of the mixing blade 34. The side surfaces of the mixing blade 34 can be surface treated.

[0077] A diameter of the through holes can range between 5 mm and 50 mm. The material webs located between the through holes may have a size of a few mm. Overall, the hole pattern 36 with the through holes may form a total opening area which accounts for between 40% to 80% of the total face of the mixing blade 34.

[0078] FIG. 7 shows a partial area of the hole pattern 36 in greater detail, wherein the hole pattern 36 is formed from a plurality of through holes arranged in rows next to one another in a grid. Grid or material webs with corresponding flow edges remain between the through holes, which ensure for good swirl and a particularly finely distributed formation of cavities over the surface of the mixing blade 34. In principle, a web width between the holes can be between 10% and 40%, preferably between 16% and 33%, of the hole diameter. Here, a sheet thickness may be between 20% to 75%, preferably between 33% to about 66%, of the hole diameter. Preferably, the hole diameter is between 10 mm to 20 mm, more preferably about 12 mm.

[0079] Referring to FIG. 7, a lower corner portion of the mixing blade 34 may be chamfered or angled.