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EP-3866980-B1 - A GRINDING MILL

EP3866980B1EP 3866980 B1EP3866980 B1EP 3866980B1EP-3866980-B1

Inventors

  • GREEN, NICHOLAS
  • BERGER, BRIAN
  • BORDI, Damon
  • WINTHER, KJELL
  • HOLSHAGEN, Bjoern

Dates

Publication Date
20260513
Application Date
20190423

Claims (17)

  1. An open-ended grinding mill (1) comprising: a drum (2) comprising a cylindrical shell (3), wherein a longitudinal axis (4) of the drum is arranged in a substantially horizontal position in a use position of the open-ended grinding mill (1), wherein the drum (2) comprises a first end (5) at a feed end of the cylindrical shell and a second end (6) at a discharge end of the cylindrical shell (3), a bearing (8) supporting the drum (2) at the second end (6) of the drum, and a support structure (9) to connect the drum (2) to the bearing (8), wherein the support structure (9) provides a wall external to the cylindrical shell (3), whereby the cylindrical shell (3) and the support structure (9) provide a double-wall structure separating the bearing (8) from an inside of the drum (2).
  2. The grinding mill (1) according to claim 1, wherein the cylindrical shell (3) is formed, at least at the second end (6) of the drum (2), of at least two shell segments (3a, 3b, 3c, 3d) split in a transverse direction of the drum (2), and wherein the cylindrical shell (3) and the support structure (9) are attached to one another at the second end (6) of the drum in such a manner, that splits of the shell segments (3a, 3b, 3c, 3d) are indexed from splits of support structure segments (9a, 9b, 9c, 9d) of the support structure (9).
  3. The grinding mill (1) according to claim 2, wherein the number of support structure segments (9a, 9b, 9c, 9d) is in the range of 2 to 8 segments.
  4. The grinding mill (1) according to claim 1, wherein the support structure (9) comprises a journal.
  5. The grinding mill (1) according to claim 4, wherein the support structure (9) comprises a longitudinal part (14) and a radial part (13), and wherein the longitudinal part (14) is configured to form a counter surface (15) for the bearing (8).
  6. The grinding mill (1) according to claim 5, wherein the support structure (9) comprises at least two support structure segments (9a, 9b, 9c, 9d) mounted to one another in such a manner, that the longitudinal part (14) of the support structure (9) is fully supported over its length in a direction of the longitudinal axis (4) of the drum (2).
  7. The grinding mill (1) according to claim 4, wherein the support structure (9) has a T-shaped cross section.
  8. The grinding mill (1) according to claim 4, wherein the support structure (9) has a Y-shaped cross section.
  9. The grinding mill (1) according to claim 4, wherein the support structure (9) has an H- or semi-H-shaped cross section.
  10. The grinding mill (1) according to claim 1, wherein the support structure (9) comprises spheroidal graphite iron.
  11. The grinding mill (1) according to claim 1, wherein the support structure (9) is removably attached to the cylindrical shell (3).
  12. The grinding mill (1) according to claim 11, wherein the support structure (9) is removably attached to the cylindrical shell (3) by bolts.
  13. The grinding mill (1) according to claim 1, wherein the cylindrical shell (3) comprises a first flange (7) extending in a radial direction of the cylindrical shell (3) at the second end (6) of the drum (2) and the support structure (9) is attached to the first flange (7).
  14. The grinding mill (1) according to claim 1, wherein the grinding mill (1) is a fully open-ended grinding mill.
  15. The grinding mill (1) according to claim 1, wherein the grinding mill (1) is a semi-open-ended grinding mill.
  16. The grinding mill (1) according to claim 15, wherein the grinding mill (1) comprises a circular open pulp lifter to transport slurry to a discharge opening of the grinding mill.
  17. The grinding mill (1) according to claim 1, wherein the support structure (9) comprises a cast structure.

Description

BACKGROUND The invention relates to grinding mills, and more particularly to open-ended grinding mills. Grinding mills, specifically semi autogenous and autogenous mills, rely on their ability to generate impact breakage of the ore charge and transport the ground material through the discharge pulp lifters out of the mill. It is common with increasing mill diameters and flow rates for the discharge arrangement to restrict the performance of the mill by limiting material transfer rates and grinding efficiency. This is due to an inability to transport the ground material through the grate and pulp lifters limiting the transfer rate due to slurry flow back/short circuiting and carry over. The impact of this restriction in mill flow rate is a reduction in mill performance (product size) due to the resulting slurry pool which dissipates the energy of the balls/ore impacting the toe of the charge. An example of a grinding mill with a conventional end wall and a riding ring integrally formed with the end wall, typically at the inlet head, is disclosed in publication US2014203128A1. While open ended mills can provide a solution to this problem removing the need for pulp lifters such that slurry can flow unhindered though the grate and out of the mill. However, this approach has been limited to very small grinding mills, as the open ended design has not been sufficiently stiff to support a journal with discrete bearing support points with increasing mill diameters and charge loads. In order to achieve acceptable deflections at the journal, shell supported mills typically have a head plate supporting the journal with a large compound butt weld between them. This is the highest stressed point on the mill so the weld must be very large to facilitate a smooth radius at the transition in geometry minimising stresses. Due to the volume of weld material this connection can be problematic with reliability potentially reduced by the presence of weld defects and residual stresses. One of the problems associated with known open-ended grinding mills has, thus, been that in case of a malfunction there is a risk that oil from bearings supporting a drum of the grinding mill comes into contact with the material to be ground causing contamination of the material. BRIEF DESCRIPTION An object of the present invention to provide a new grinding mill. The objects of the invention are achieved by a grinding mill that is characterized by what is stated in the independent claim. Some preferred embodiments are disclosed in the dependent claims. The invention is based on the idea of preventing a continuous path from being formed between the inside of the drum of the grinding mill and the oil in the bearing even during malfunction. An advantage of the grinding mill is that contamination of the material to be ground is effectively prevented. BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which Figure 1 illustrates schematically a grinding mill seen from a side;Figure 2 illustrates schematically a grinding mill seen from the second end;Figure 3 illustrates schematically a detail of a shell and an embodiment of a support structure at two cross sections along the periphery of the shell and the support structure;Figure 4 illustrates schematically a detail of a shell and another embodiment of a support structure at three cross sections along the periphery of the shell and the support structure;Figure 5 illustrates schematically a detail of a shell and a third embodiment of a support structure at three cross sections along the periphery of the shell and the support structure;Figure 6 illustrates schematically a shell and an embodiment of a support structure;Figure 7 illustrates schematically a shell and another embodiment of a support structure; andFigure 8 illustrates schematically a shell and a third embodiment of a support structure. The drawings are intended to illustrate the main principles described in this description and the embodiments only. The drawings are not shown in scale and not all the similar features are provided with reference numbers in the drawings for sake of clarity. DETAILED DESCRIPTION OF THE INVENTION Figure 1 is illustrates schematically a grinding mill 1. Figure 2 illustrates schematically a grinding mill 1 seen from a second end 6, in other words the discharge end of the grinding mill. Figures 1 and 2 only show some features of the grinding mill 1 that help understanding the current solution. It is clear for a person skilled in the art that a grinding mill may and usually does comprise other features as well. A grinding mill 1, such as the grinding mill of Figure 1, comprises a drum 2 comprising a cylindrical shell 3. In a grinding mill 1 of the current solution, the longitudinal axis 4 of the drum 2 is arranged in a substantially horizontal position in a use position of the grinding mill