The invention relates to a vertical mill with a grinding track and at least one grinding roller.
A wide variety of embodiments of vertical mills are known from the prior art. These mills usually comprise a rotatably disposed grinding ring on the top side of which an annular grinding track is formed. In most cases a plurality of grinding rollers are distributed over the circumference of this grinding track and come into rolling contact with the grinding track during crushing.
A roller mill of this kind is known, for example, from DE-A-195 03 179. A vertical mill in which the grinding roller and the grinding track are of the same width is described in U.S. Pat. No. 984,584.
During the grinding process the grinding tools and, in particular, the grinding track are subject to increasing wear, which has an adverse effect on the throughput and the specific energy requirement of the vertical mills. This can be explained by the unwanted significant grinding bed thickness which occurs as a result of an unfavourable wear contour of the grinding track. As is particularly evident from
The object of the present invention is to improve the vertical mill such that a substantially constant grinding bed thickness can be obtained during the entire running time.
This object is solved according to the invention by the features of Claim 1.
Further configurations of the invention constitute the subject matter of the subclaims.
The vertical mill according to the invention essentially comprises a grinding track and at least one grinding roller, the grinding track comprising a central zone of a harder material and two laterally adjacent edge zones of a softer material, with the width of the central zone being smaller than or equal to the width of the grinding roller.
A configuration of this kind enables the formation of disturbing ridges according to
The grinding rollers may in particular be crowned, cylindrical and conical. According to one preferred configuration of the invention, the width of the grinding track or the width of the central zone is smaller than the width of the grinding roller. The width of the grinding track or the width of the central zone is preferably between 75% and 95% of the width of the grinding roller.
In a further configuration of the invention the grinding track is disposed on the surface of a grinding ring, the grinding track being delimited on both sides by fittings, and seals being provided between the grinding ring and the fittings.
The grinding material consists in particular of binding agents (granulated blast furnace slag, cement clinker) and raw materials for cement production (limestone). In this case the grinding roller presses with a pressure of 600 to 1800 kN/m2 (force on projected roller face).
Further advantages and configurations of the invention are illustrated in detail on the basis of the description of several examples and the drawings.
In the drawings
The vertical mill which is represented in a detail view in
Fittings 4, 5 are provided on both sides of the grinding track 1, these being disposed at a radial distance from the grinding track. These fittings serve to delimit the grinding material layer. The grinding track 1 comprises a central zone 1a of a harder material and two laterally adjacent edge zones 1b, 1c of a softer material. Here the width a of the central zone 1a is smaller than or equal to the width b of the grinding roller 2. As the edges zones 1b, 1c are made of a softer material, no disturbing ridges form here. This configuration enables the grinding roller 2 to penetrate deeply and unchecked into the grinding bed during the entire operating time of the grinding track. Either no ridges at all occur at the edge of the central zone 1a or such ridges are removed by the grinding roller. The wear pattern which is represented in
Seals 7, 8 are provided between the fittings 4 and 5, respectively, and the grinding ring 3 in order to guarantee sufficient sealing between the grinding track and the laterally adjacent zones at the end of the operating time.
In the case of the grinding track 1′ which is represented in
In the represented embodiments the grinding rollers 2 are in each case of crowned formation. However, as indicated by broken lines in
According to one preferred configuration, the width a of the central zone 1a, 1′a is smaller than the width b of the grinding roller, the width a preferably being between 75% and 95% of the width b of the grinding roller.
The vertical mills described above are distinguished by a grinding track which is narrower when compared with the prior art and which has the advantage of a constant grinding bed thickness being obtained over the entire running time. A longer working life is also obtained with this design, in spite of the lower wearing weight.
Number | Date | Country | Kind |
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10 2005 010 069.4 | Mar 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2006/001842 | 2/28/2006 | WO | 00 | 5/6/2008 |