VERTICAL ROLL MILL

Abstract

A vertical roll mill may include a grinding plate, a grinding roll, a nozzle ring that horizontally surrounds the grinding plate, an air feed apparatus disposed under the nozzle ring, a discharge element disposed below or in a region of the air feed apparatus, and a bypass apparatus disposed in the nozzle ring. The bypass apparatus may form a connection between the nozzle ring and the discharge element. Further, the bypass apparatus can discharge particles that are difficult to grind, for example, ductile particles such as iron particles, from the grinding process. In some examples, the bypass apparatus includes a gas-impermeable outer skin in the region of the air feed apparatus.

Claims

1.-17. (canceled)

18. A vertical roll mill comprising: a grinding plate; a grinding roll; a nozzle ring that horizontally surrounds the grinding plate; an air feed apparatus disposed under the nozzle ring; a discharge element disposed below or in a region of the air feed apparatus; and a bypass apparatus disposed in the nozzle ring, the bypass apparatus forming a connection between the nozzle ring and the discharge element.

19. The vertical roll mill of claim 18 wherein the bypass apparatus comprises a gas-impermeable outer skin in the region of the air feed apparatus.

20. The vertical roll mill of claim 18 wherein the bypass apparatus is one of a plurality of bypass apparatuses and the grinding roll is one of a plurality of grinding rolls, wherein a quantity of the plurality of bypass apparatuses corresponds to a quantity of the plurality of grinding rolls.

21. The vertical roll mill of claim 18 wherein the bypass apparatus is one of at least two bypass apparatuses, wherein the at least two bypass apparatuses are disposed equidistantly in the nozzle ring.

22. The vertical roll mill of claim 18 wherein the bypass apparatus comprises a cross-sectional area at a surface of the nozzle ring, wherein the cross-sectional area of the bypass apparatus amounts to less than 2.5% of a surface area of the grinding plate.

23. The vertical roll mill of claim 18 wherein the bypass apparatus comprises a cross-sectional area at a surface of the nozzle ring, wherein the cross-sectional area of the bypass apparatus amounts to less than 1.0% of a surface area of the grinding plate.

24. The vertical roll mill of claim 18 wherein the bypass apparatus comprises a cross-sectional area at a surface of the nozzle ring, wherein the cross-sectional area of the bypass apparatus amounts to less than 0.5% of a surface area of the grinding plate.

25. The vertical roll mill of claim 18 wherein the bypass apparatus is one of a plurality of bypass apparatuses, wherein a sum of all cross-sectional areas of the plurality of bypass apparatuses at a surface of the nozzle ring amounts to less than 10% of a surface area of the nozzle ring.

26. The vertical roll mill of claim 18 wherein the bypass apparatus is one of a plurality of bypass apparatuses, wherein a sum of all cross-sectional areas of the plurality of bypass apparatuses at a surface of the nozzle ring amounts to less than 5% of a surface area of the nozzle ring.

27. The vertical roll mill of claim 18 wherein a largest cross section of the bypass apparatus is less than 250 mm.

28. The vertical roll mill of claim 18 wherein a largest cross section of the bypass apparatus is less than 20 mm.

29. The vertical roll mill of claim 18 further comprising a separator disposed downstream of the discharge element.

30. The vertical roll mill of claim 29 further comprising a material return line to the grinding plate, the material return line being disposed downstream of the separator.

31. The vertical roll mill of claim 29 wherein the separator is a magnetic separator.

32. The vertical roll mill of claim 31 wherein the magnetic separator is either a drum-type magnetic separator or an overbelt magnetic separator.

33. The vertical roll mill of claim 18 wherein the bypass apparatus comprises a larger cross-sectional area at an upper end at the nozzle ring than at a lower end at the discharge element.

34. The vertical roll mill of claim 18 wherein the bypass apparatus is disposed within a region of the air feed apparatus that exhibits a below-average throughflow.

Description

[0039] Below, the vertical roll mill according to the invention will be discussed in more detail on the basis of an exemplary embodiment illustrated in the drawings.

[0040] FIG. 1 shows a schematic cross section through a vertical roll mill.

[0041] FIG. 2 shows a schematic plan view of a vertical roll mill.

[0042] FIG. 3 shows a schematic illustration of a bypass apparatus.

[0043] FIG. 1 shows a schematic cross section of the vertical roll mill 10, and FIG. 2 shows a schematic plan view onto the plane of the grinding plate 20. The grinding plate 20 comprises for example a diameter of approximately 4.5 m, and the nozzle ring 40 comprises a width of approximately 40 cm. In this exemplary vertical roll mill 10, three grinding rolls 30, of which only one is visible in FIG. 1, are situated above the grinding plate 20. Situated below the nozzle ring 40 is the air feed device 50, into which air is introduced by three air inlets (visible in FIG. 2), which air rises upward through the nozzle ring 40 and discharges the ground product from the vertical roll mill 10. In the region of the air feed device 50 there is arranged a discharge element 60 in which material that falls through the nozzle ring 40 is captured. Said material generally comprises large and relatively heavy particles. These are fed through a closure flap 80 to a separator 90. In the separator 90, which in this example is designed as a magnetic separator, iron particles are removed. The remaining material is fed via the return line 100 back to the grinding plate 20. Furthermore, the vertical roll mill 10 comprises an air outlet 105. This construction corresponds in this respect to a vertical roll mill according to the prior art.

[0044] The vertical roll mill 10 according to the invention additionally comprises, in the example shown, three bypass apparatuses 70 which lead from the nozzle ring 40 into the discharge element 60. Since the discharge element 60 is designed in the form of a depression below the air feed device 50, said region exhibits reduced flow, whereby only very little air is conducted from the air inlet 55 through the air feed device 50, the discharge element 60 and the bypass apparatuses 70. As a result, the flow above the bypass apparatuses 70 is greatly reduced, and it is thus possible for even small and relatively lightweight iron particles to be discharged through the bypass apparatuses 70.

[0045] As emerges from FIG. 2, the bypass apparatuses 70 are oriented with a maximum spacing in terms of flow to the three air inlets 55. In this way, the air flowing through the bypass apparatuses 70 is additionally reduced.

[0046] FIG. 3 shows a bypass apparatus 70, wherein the bypass apparatus 70 comprises, in the upper region, additional material-guiding panels 75 which, in the region of the nozzle ring 40, increase the introduction of material into the bypass apparatus 70. FIG. 3a shows, in cross section, the funnel function of the material-guiding panel 75, and FIG. 3b clearly shows, in plan view, the relationship between the diameter of the bypass apparatus 70 and that of the material-guiding panel.

REFERENCE DESIGNATIONS

[0047] 10 Vertical roll mill [0048] 20 Grinding plate [0049] 30 Grinding roll [0050] 40 Nozzle ring [0051] 50 Air feed device [0052] 55 Air inlet [0053] 60 Discharge element [0054] 70 Bypass apparatus [0055] 75 Material-guiding panel on bypass apparatus [0056] 80 Closure flap [0057] 90 Separator [0058] 100 Return line [0059] 105 Air outlet