CN211359046U

CN211359046U - Grinding mill, pulp lifter and external pulp lifter element

Info

Publication number: CN211359046U
Application number: CN201790001701.4U
Authority: CN
Inventors: A·希思; A·帕斯; A·德尔比安科; T·艾德
Original assignee: Outotec Finland Oy
Current assignee: Metso Minerals Ltd; Metso Finland Oy
Priority date: 2017-03-20
Filing date: 2017-03-20
Publication date: 2020-08-28
Anticipated expiration: 2027-03-20
Also published as: AU2017405653B2; AU2017405653A1; EA201992047A1; EA038752B1; CA3057258C; PE20191522A1; ZA201906556B; CA3057258A1; BR112019019641A2; MX2019011115A; WO2018172594A1

Abstract

An external pulp lifter element (1) for a pulp lifter (2) of a rotating drum mill (3), comprising a first wall (4) directed towards the discharge end of the mill, and at least one blade (6) protruding from an inner surface (12) of the first wall (4) towards the interior of the drum mill (3) and comprising a guide surface (10) on the front side of the blade (6). The outer edge (11) of the guide surface (10) is angled with respect to the inner surface (12) of the first wall (4) such that the angle (θ) between the inner surface (12) of the first wall (4) and the outer edge (11) of the guide surface (10) is less than 90 degrees. The present application further provides a pulp lifter and a grinding mill. The utility model discloses a more effective flow of material and the lower power consumption of the abrasive material of every unit of producing are realized to simple structure.

Description

Grinding mill, pulp lifter and external pulp lifter element

Technical Field

The present invention relates to grinding mills, and more particularly to pulp lifters and external pulp lifter elements.

Background

One of the problems associated with pulp lifters is that ground material that has been lifted to the pulp lifter tends to fall back to the mill drum. This is inefficient in terms of both flow rate and power consumption.

CN204866029 discloses a discharge end liner for a large mining semi-automatic mill, consisting of a pulp lifter on which the lifting bars of the pulp lifter are arranged and a grid plate on which the grid lifting bars are arranged. A plurality of discharge end liners are circumferentially adjacent to each other and each lifting bar or each grid lifting bar of a pulp lifter is constituted by an arched lifting bar 5 and an arched lifting bar 6 and is each adjacent to two pulp lifters or grid plates, wherein the curved lifter 5 of a pulp lifter or grid plate is connected to the head of the curved lifting bar 6 of another block and constitutes a combined arched lifting bar extending to the outer edge of the discharge end liner, and adjacent discharge channels are formed between the two combined arched lifting bars.

SUMMERY OF THE UTILITY MODEL

It is therefore an object of the present invention to provide a new grinding mill, a new pulp lifter and a new external pulp lifter element. The object of the invention is achieved by a grinding machine, a pulp lifter and an external pulp lifter element.

The utility model discloses based on such thought: pockets are formed in the pulp lifter by positioning the blades of the pulp lifter element at an angle relative to the wall of the pulp lifter element.

The advantage of the arrangement of the present invention is that a more efficient flow of material and a lower power consumption per unit of abrasive material produced can be achieved by a simple structure. Certain additional advantages are disclosed in the detailed description in connection with the embodiments.

Drawings

The invention will be described in more detail hereinafter by means of preferred embodiments with reference to the accompanying drawings, in which:

FIG. 1 shows a grinding mill;

FIG. 2 illustrates an embodiment of an external pulp lifter element for a pulp lifter, in conjunction with details of the pulp lifter assembly;

FIG. 3 illustrates an embodiment of an external pulp lifter element for a pulp lifter in connection with details of the pulp lifter assembly;

FIG. 4 illustrates an embodiment of an outer pulp lifter element in conjunction with details of a pulp lifter assembly;

FIG. 5 illustrates an embodiment of an external pulp lifter in connection with details of the pulp lifter assembly; and

FIG. 6 illustrates an angle θ in the outer pulp lifter element.

Detailed Description

Fig. 1 shows a grinding mill 3, more specifically a rotary drum grinding mill. Grinders are used to process hard solid materials so that large solid materials are ground into smaller pieces.

The grinding mill 3 may comprise a cylindrical housing 20, which is rotatably arranged about its longitudinal axis D extending in horizontal direction. The material to be ground may be received into the cylindrical housing 20, for example, through a feed slot (not numbered). Grinding is performed inside the cylindrical housing 20 by lifting the material to be ground inside the cylindrical housing 20 and dropping the material to be ground. Lifting bars or lifting plates (not shown, but their position within the cylindrical housing is shown by dashed lines in fig. 1) may be used to lift material inside the cylindrical housing. According to one embodiment, discrete grinding elements (such as balls comprising, for example, stone or metallic material) may be provided inside the cylindrical housing to aid in grinding.

The grinding mill 3 may comprise at least one inlet 21 for receiving continuously fed material to be ground. The material to be ground may comprise, for example, mineral ore. The grinding mill 3 may also comprise at least one outlet 22 for continuously discharging the ground material. The material being ground may comprise, for example, a pulp. The inlet(s) 21 and the outlet(s) 22 may be provided at opposite ends of the cylindrical housing in the direction of the longitudinal axis D of the cylindrical housing. Thus, a continuous grinding process can be provided by: the material to be ground is fed into the cylindrical housing 20 through inlet(s) 21, ground by lifting and dropping the material to be ground on its way through the cylindrical housing 20 as it moves through and within the cylindrical housing 20, and discharged through outlet(s) 22 at the opposite end of the cylindrical housing.

The grinding mill 3 may further comprise a grate (grate)23 disposed between the interior of the cylindrical housing 20 and the outlet 22. The grid 23 may include openings 31 for passing particles of ground material of a predetermined size or less. In other words, the opening 31 may be sized such that particles of a predetermined size or smaller fit through the opening 31 and may therefore move towards the outlet 22, and particles larger than the predetermined size do not fit through the opening but fall back into the interior of the cylindrical housing for further grinding. Thereby, the grid prevents particles larger than a predetermined size from passing through the grid. The grinding mill 3 may also include a discharger 24 provided at the outlet 22 end of the grinding mill for discharging the ground material through the outlet 22.

The mill 3 may further comprise a pulp lifter 2. The pulp lifter 2 may comprise at least one external pulp lifter element 1 and/or pulp lifter 2 arranged between the grate and the discharger for guiding ground material from the cylindrical housing to the discharger 24. More particularly, when the pulp lifter 2 is arranged to rotate with the cylindrical shell about the longitudinal axis D of the cylindrical shell, the pulp lifter 2 may be arranged to lift the ground material passing through the grate 23 to the outlet 22 for discharge of the ground material through the discharger 24. According to this embodiment, the pulp lifter 2 may be arranged to rotate with the cylindrical shell in a clockwise or counter-clockwise direction. Various embodiments of such an external pulp lifter element 1 and/or pulp lifter 2 are described in the description.

The pulp lifter 2 may comprise at least one external pulp lifter element 1. Typically, the pulp lifter 2 comprises a plurality of outer pulp lifter elements 1. According to one embodiment, the outer pulp lifter element 1 comprises the shape of a sector or a truncated sector, and a plurality of such outer pulp lifter elements 1 may be arranged circumferentially side by side, whereby the outer pulp lifter elements 1 may form a disc-shaped or annular pulp lifter 2. According to one embodiment, the pulp lifter 2 may comprise 15 to 35 outer pulp lifter elements 1. According to another embodiment, the pulp lifter 2 may comprise 18 to 32 outer pulp lifter elements 1.

The disc-shaped or annular pulp lifter 2 may comprise, for example, a conical shape as can be seen in fig. 1. The pulp lifter 2 may be arranged at and conform to the shape of the end of the cylindrical shell such that the middle point F of the pulp lifter 2 may be arranged on the longitudinal axis of the cylindrical shell. The pulp lifter 2 may be rotatably arranged in the mill 3 such that the pulp lifter 2 as a whole is rotatable together with the cylindrical shell 20 about the longitudinal axis D of the cylindrical shell. According to the described embodiments, all outer pulp lifter elements 1 in the pulp lifter 2 may be similar to each other, or the pulp lifter 2 may comprise different types of outer pulp lifter elements 1.

Fig. 2, 3, 4 and 5 show an embodiment of an external pulp lifter element 1 for a pulp lifter 2, such as a pulp lifter 2 for a rotary drum mill 3. More particularly, fig. 2 shows a portion of such a pulp lifter 2 for a rotary drum mill 3. The outer pulp lifter element 1 may form a sector or a truncated sector of the outer pulp lifter. In other words, the outer pulp lifter element 1 may comprise a fan shape or a truncated fan shape, and a plurality of such outer pulp lifter elements 1 may be arranged circumferentially side by side to form an outer pulp lifter of the pulp lifter 2.

The outer pulp lifter element 1 may comprise a first wall 4 directed towards the discharge end of the mill 3. In other words, the first wall 4 may be arranged on the side of the outer pulp lifter element 1 opposite to the side where the grate 23 is arranged.

The outer pulp lifter element 1 may also comprise at least one blade 6 protruding from the inner surface 12 of the first wall 4 towards the inside of the drum mill 3. The blades 6 may be arranged to lift material passing through the grate 23 towards the middle of the pulp lifter 2 and thus towards the outlet 22. According to one embodiment, the outer pulp lifter element 1 may comprise only one blade 6. According to another embodiment, the outer pulp lifter element 1 may comprise two blades 6 or a plurality of blades 6. According to yet another embodiment, the blades 6 may extend to two or more outer pulp lifter elements 1. In other words, the blades 6 may comprise blade parts which may be arranged in different outer pulp lifter elements 1, such that the blades 6 are formed when the outer pulp lifter elements 1 are mounted together.

Each blade 6 may extend from an outer portion of the outer pulp lifter element 1 towards an inner end 9 of the outer pulp lifter element 1. In other words, the blades may extend from a region at or near the perimeter toward the midpoint F of the pulp lifter 2. Thus, the inner end 9 of the outer pulp lifter element 1 refers to the end of the outer pulp lifter element 1 that is directed towards the middle point F of the pulp lifter 2.

The blade 6 may comprise a guide surface 10 on the front side of the blade 6. The front side of the blade 6 refers to the foremost side of the blade 6 in the rotational direction. In other words, the front side of the blade is the side that first receives ground material (such as pulp, e.g. pulp) when the pulp lifter element 1, and more particularly the blade 6, is in the lifting phase of the cycle. Thus, the front side of the blades depends on the direction of rotation of the pulp lifter 2. In a pulp lifter 2 rotating in a first direction, the leading side of the blade is thus on a first side of the blade 6, whereas when the pulp lifter 2 rotates in the opposite direction, the leading side of the blade is the side of the blade opposite to said first side.

According to one embodiment, blades 6 may extend radially from an outer portion of the outer pulp lifter element towards an inner end of the outer pulp lifter element, such as in the embodiment of FIGS. 4 and 5.

According to another embodiment, blades 6 may extend in a curved manner from an outer portion of the outer pulp lifter element towards an inner end of the outer pulp lifter element, such as in the embodiment of FIGS. 2 and 3. In other words, the blades 6 may include a concave guiding surface 10 that forms a helical configuration with the inner portion of the pulp lifter 2. In embodiments having an opposite direction of rotation compared to the direction of rotation of fig. 2 and 3, the opposite spiral direction will provide a similar effect of optimally directing the ground material toward the middle of the pulp lifter.

At least a portion of the outer edge 11 of the guide surface 10 may be angled with respect to the inner surface 12 of the first wall 4. Throughout the description, this feature refers to the outer edge 11 of the guide surface 10 being angled with respect to the inner surface 12 of the first wall 4 for the sake of clarity, however, the purpose of the angled relationship is to form a pocket-like shape that prevents the abraded material from falling from the guide surface, and the effect can be achieved even if only a portion of the outer edge 11 is angled with respect to the inner surface 12 of the first wall 4.

The outer edge 11 of the guide surface 10 comprises the edge of the guide surface closest to the outer periphery of the pulp lifter 2. According to one embodiment, the outer edge 11 of the guide surface 10 may have a rectilinear profile or shape, and the line may be angled with respect to the inner surface 12 of the first wall 4. According to another embodiment, the outer edge 11 of the guide surface 10 may comprise a concave profile or shape, wherein at least a portion of the outer edge 11 is angled with respect to the inner surface 12 of the first wall 4. In such embodiments, the angled portion of the outer edge may also refer to a tangential direction along the concave outer edge 11. Similarly, the outer edge of the guide surface may comprise a convex profile or shape, and the angled portion of the outer edge may thus also comprise a tangent along the convex outer edge 11. Naturally, the outer edge 11 may comprise a profile or shape that is a combination of a curved portion and a straight portion, wherein at least a portion of the outer edge 11 is angled with respect to the inner surface 12 of the first wall 4.

The angle theta between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 may be less than 90 degrees. The inner surface 12 of the first wall 4 may be parallel to the head of the grinding mill. In other words, the inner surface 12 of the first wall 4 may be parallel to the discharge end of the mill. The effect of the angle theta between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 being less than 90 degrees is that it guides the flow of ground material, such as a pulp flow, towards the rear of the pulp lifter in a more efficient manner. For illustration, the angle θ and the direction of rotation C in the outer pulp lifter element 1 are shown in detail in FIG. 6. In a pulp lifter 2 with opposite rotational directions, a similar but opposite side angle θ of the outer pulp lifter element will have the same effect.

Some advantages of such an external pulp lifter element 1 include: preventing ground material, such as slurry, from falling back into the interior of the drum, i.e., back into the interior of the cylindrical shell, but without increasing the complexity of the pulp lifter structure to retain the ground material in the pulp lifter; keeping the ground material flow away from the back of the grid, which generally has a rough texture and tends to slow down the material flow, thereby reducing the efficiency of the grinding machine; and reducing wear on the back side of the grid due to abrasive material, such as slurry, traveling along the back side of the grid.

According to one embodiment, the angle θ between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 may be less than 88 degrees. According to another embodiment, the angle θ between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 may be in the range of 20 degrees to 70 degrees. This is particularly advantageous because an angle theta between the inner surface 12 of the first wall 4 and the outer edge 11 of the guiding surface 10 of less than 20 degrees is more difficult and expensive to build, whereas an angle of 70 degrees or less may provide good guiding properties for the outer pulp lifter element 1 and its guiding surface 10. According to another embodiment, the angle θ between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 may be in the range of 30 degrees to 60 degrees. According to yet another embodiment, the angle θ between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 may be about 45 degrees.

According to an embodiment, such as the embodiment of fig. 3, the outer pulp lifter element 1 may comprise a second surface 7, which extends in the radial direction B of the pulp lifter 2 and forms the front surface of the pulp lifter element 1 in the direction of rotation C of the pulp lifter 2. The front surface of the pulp lifter element refers to the foremost surface in the direction of rotation C, which is the surface: ground material (such as slurry) from an adjacent (more particularly leading) outer pulp lifter element first enters the outer pulp lifter element through the surface. The second surface 7 may include an opening 8 for receiving ground material from an adjacent external pulp lifter element. According to one embodiment, the second surface 7 may be substantially perpendicular to the first wall 4.

In such an embodiment, the direction of the inner surface 12 of the first wall 4 may be defined by the first wall 4 side edges of the opening 8, which first wall 4 side edges extend in the direction a-a' parallel to the head of the mill in fig. 6 and the radial direction B of the pulp lifter 2. The outer edge 11 of the guide surface 10 may comprise the outer edge of the opening 8. Thus, the angle θ between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10 may comprise the angle between the side edge of the first wall 4 of the opening 8 and the outer edge of the opening 8, e.g. as can be seen in fig. 6.

According to one embodiment, the vanes 6 may have an equal angle between the inner surface 12 of the first wall 4 and the guide surface 10 along the entire length of the guide surface 10. In other words, the blades 6 may be inclined by a similar amount along the entire length of the guide surface 10, i.e. the blades may have the same angle compared to the direction a-a' in fig. 6, for example, along the blade from the outer end of the blade (i.e. the end closest to the outer end of the pulp lifter) to the inner end of the blade (i.e. the end closest to the outlet and discharger of the mill).

According to one embodiment, the angle between the inner surface 12 of the first wall 4 and the guiding surface 10 of the blade 6 may vary along the length of the guiding surface 10. According to one embodiment, the angle between the inner surface 12 of the first wall 4 and the guiding surface 10 of the blade 6 may be reversed at one point of the guiding surface 10. Thus, in such embodiments, the angle between the inner surface 12 of the first wall 4 and the guide surface 10 of the blade 6, at the inner end of the blade and/or at a point along the guide surface of the blade, may be different from the angle θ between the inner surface 12 of the first wall 4 and the outer edge 11 of the guide surface 10. With such an embodiment, an improved movement of the ground material along the guide surface 10 may be achieved. Embodiments in which the angle is reversed at one point of the guide surface may be particularly advantageous for directing the ground material to the discharger and outlet.

According to one embodiment, the outer pulp lifter element may comprise a solid cast steel material. According to another embodiment, the outer pulp lifter element may comprise a rubber material facing with a steel frame disposed inside. According to another embodiment, the outer pulp lifter element may include an elastomeric material, such as urethane.

According to one embodiment, a pulp lifter 2 for a rotary drum mill 3 may comprise at least one external pulp lifter element 1 as described in this specification.

According to an embodiment, the pulp lifter 2 may further comprise an internal pulp lifter 16. The blades 6 may thus extend to the internal pulp lifter 16.

According to one embodiment, at least a portion of the guide surface 17 of the inner pulp lifter portion of the blade 6 may also be angled with respect to the inner surface of the rear wall 18 of the inner pulp lifter. According to another embodiment, the guide surfaces 17 of the inner pulp lifter portion of the blade 6 may be arranged on opposite sides of the blade 6 on the area of the inner pulp lifter when compared to the area of the outer pulp lifter. The opposite side of the blade 6 refers to the back side of the blade in the direction of rotation of the pulp lifter. This is beneficial because if the material passes over the outlet at the highest point of the rotation cycle of the pulp lifter, i.e. does not exit the pulp lifter through the outlet, the ground material will fall to the opposite side due to gravity. According to another embodiment, the vanes 6 may also extend to the eductor 24.

According to one embodiment, at least a portion of the guide surface 25 of the discharger portion of the vane 6 may also be angled with respect to the inner surface of the discharger wall 26. When the outer pulp lifter element 1, the inner pulp lifter element 16 and the discharger 24 are assembled together (e.g. in the grinding mill 3), this inner surface of the discharger wall 26 may form a substantially continuous surface with the inner surface of the rear wall 18 of the inner pulp lifter element 16 and the inner surface 12 of the first wall 4 of the outer pulp lifter element 1.

According to one embodiment, the grate 23 may comprise at least one grate lifter 27 arranged on the inside of the cylindrical housing of the grate 23 for guiding the particles of ground material into the pulp lifter 2 through openings in the grate 23. This may be done in a similar manner to the blades in a pulp lifter; that is, the grate lifter may lift the ground material as the grate rotates. Thus, the outer edge 28 of the grill lifter guide surface 30 may be angled with respect to the grill wall 29 facing the interior of the cylindrical housing 20 such that the angle a between the grill wall 29 and the grill lifter guide surface 30 is less than 90 degrees at least at the outer edge of the grill lifter 27.

According to another embodiment, the angle α may be less than 88 degrees. According to another embodiment, the angle α may be in the range of 20 degrees to 70 degrees. According to another embodiment, the angle α may be in the range of 30 to 60 degrees. According to yet another embodiment, the angle α may be about 45 degrees.

According to one embodiment, the angle α may vary along the length of the grid lifter guide surface 30. According to one embodiment, the angle α may be reversed at a point of the grid lifter guide surface 30. Thus, in such embodiments, the angle at the inner end of the grid lifter and/or at a point along the grid lifter guide surface may be different from the angle α. With such an embodiment, an improved movement of the ground material along the grid lifter guide surface 30 may be achieved. Embodiments in which the angle is reversed at a point of the grate lifter guide surface may be particularly advantageous for guiding ground material to the pulp lifter.

According to one embodiment, the grate lifter and the pulp lifter may be arranged to be located on top of each other, and the angle may extend across both the grate lifter and the pulp lifter. Thus, both the inner surface of the grate lifter and the inner surface of the pulp lifter may be angled.

The grid lifter may comprise a radial form, a curved form or a spiral shape. Thus, the combination of the grate lifter shape and the pulp lifter blade shape may be combined in different ways depending on the intended use, such as by combining a radial grate lifter and a radial pulp lifter blade, a spiral grate lifter and a spiral pulp lifter blade, a radial grate lifter and a spiral pulp lifter blade or a spiral grate lifter and a radial pulp lifter blade.

According to one embodiment, the same angle θ may also extend to the grate lifter, i.e. the grate lifter guide surface and the pulp lifter guide surface may have the same angle. These guide surfaces may even form a continuous guide surface on both sides of the grid.

According to one embodiment, the mill may comprise a wet mill. Thus, the grinding mill may further comprise at least one inlet for receiving a continuously fed process liquid. This inlet for process liquid may, according to embodiments, comprise the inlet 21 or a separate inlet for process liquid.

According to one embodiment, the grinding mill 3 may comprise at least one of the following: grate discharge ball mills, SAG mills and AG mills.

According to one embodiment, the outer pulp lifter element, the inner pulp lifter element and/or the pulp lifter may constitute a spare part of the grinding mill. According to one embodiment, such spare parts may be retrofitted to existing grinding mills. The pulp lifter and its structural components (such as the outer pulp lifter element, the inner pulp lifter element, and the grate lifter) described in this specification can be retrofitted to existing mills, even though the existing mill itself has a conventional design, such as a conventional radial or spiral pulp lifter and/or grate lifter in the existing mill. In other words, the structural components of the grinding machine with conventional design can be replaced by the structural components described in this specification. Thus, a smoother and efficient flow of the ground material can be achieved, and even a longer service life of the spare part can be achieved.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. An outer pulp lifter element (1) for a pulp lifter (2) of a rotary drum mill (3), the outer pulp lifter element (1) forming a sector or a truncated sector of an outer pulp lifter and comprising:

a first wall (4) directed towards the discharge end of the mill,

and at least one blade (6) projecting from the inner surface (12) of the first wall (4) towards the inside of the rotary drum mill (3), extending from an outer part of the outer pulp lifter element (1) towards the inner end (9) of the outer pulp lifter element (1), and comprising a guide surface (10) on the front side of the blade (6) which first receives ground material, characterized in that,

at least a portion of the outer edge (11) of the guide surface (10) is angled relative to the inner surface (12) of the first wall (4) such that an angle (θ) between the inner surface (12) of the first wall (4) and the outer edge (11) of the guide surface (10) is in the range of 20 degrees to 70 degrees, thereby forming a pocket in the pulp lifter (2) and the guide surface (10) directing the flow of ground material towards the rear of the pulp lifter; and

the vanes (6) having an equal angle between the inner surface (12) of the first wall (4) and the guide surface (10) along the entire length of the guide surface (10),

or the angle between the inner surface (12) of the first wall (4) and the guide surface (10) of the vane (6) varies along the length of the guide surface (10).

2. An external pulp lifter element (1) according to claim 1, characterized in that the angle (θ) between the inner surface (12) of the first wall (4) and the outer edge (11) of the guiding surface (10) is in the range of 30 to 60 degrees.

3. An outer pulp lifter element (1) according to claim 1 or 2, characterized in that the blades (6) extend radially from an outer portion of the outer pulp lifter element towards an inner end of the outer pulp lifter element.

4. An outer pulp lifter element (1) according to claim 1, characterized in that the blades (6) extend in a curved manner from an outer portion of the outer pulp lifter element towards an inner end of the outer pulp lifter element.

5. An outer pulp lifter element (1) according to any of claims 1, 2 or 4, characterized in that the outer pulp lifter element (1) comprises a second surface (7) substantially perpendicular to the first wall (4), which second surface extends in a radial direction (B) of the pulp lifter (1), forming a front surface of the pulp lifter element (1) in a direction of rotation (C) of the pulp lifter (2), and which second surface comprises openings (8) for receiving ground material from an adjacent outer pulp lifter element,

such that the direction of the inner surface (12) of the first wall (4) is defined by the side edges of the first wall (4) of the opening (8) extending in a direction (A-A') parallel to the head of the rotary drum mill and in the radial direction (B) of the pulp lifter (1),

an outer edge (11) of the guide surface (10) comprises an outer edge of the opening (8), and

the angle (θ) between the inner surface (12) of the first wall (4) and the outer edge (11) of the guide surface (10) comprises the angle between the side edge of the first wall (4) of the opening (8) and the outer edge of the opening (8).

6. An external pulp lifter element (1) according to claim 1, characterized in that the angle between the inner surface (12) of the first wall (4) and the guiding surface (10) of the blade (6) at the inner end of the blade and/or at a point along the guiding surface of the blade is different from the angle (θ) between the inner surface (12) of the first wall (4) and the outer edge (11) of the guiding surface (10).

7. An outer pulp lifter element (1) according to claim 1, characterized in that the outer pulp lifter element comprises a solid cast steel material.

8. An outer pulp lifter element (1) according to claim 1, characterized in that the outer pulp lifter element comprises a rubber material facing, inside which a steel frame is arranged.

9. An outer pulp lifter element (1) according to claim 1, characterized in that the outer pulp lifter element comprises an elastomeric material.

10. A pulp lifter (2) for a rotating drum mill (3), characterized in that the pulp lifter (2) comprises at least one external pulp lifter element (1) according to any of claims 1-9.

11. A pulp lifter (2) according to claim 10, characterized in that the pulp lifter comprises an internal pulp lifter (16) and the blades (6) extend to the internal pulp lifter (16).

12. A pulp lifter (2) according to claim 11, characterized in that at least a part of the guiding surface (17) of the inner pulp lifter portion of the blade (6) is also angled in relation to the inner surface of the rear wall (18) of the inner pulp lifter.

13. A pulp lifter (2) according to claim 12, characterized in that the guiding surface (17) of the inner pulp lifter portion of the blade (6) is arranged on the opposite side of the blade (6) on the area of the inner pulp lifter when compared to the area of the outer pulp lifter.

14. A grinding mill (3) comprising:

a cylindrical housing (20) rotatably arranged about its longitudinal axis (D) extending in a horizontal direction,

at least one inlet (21) for receiving a continuously fed material to be ground,

at least one outlet (22) for continuously discharging the ground material,

a grate (23) between the interior of the cylindrical housing (20) and the outlet (22), the grate comprising openings for passage of particles of ground material of a predetermined size or less, whereby the grate prevents particles larger than the predetermined size from passing through the grate, and

a discharger (24) arranged at the outlet (22) end of the mill for discharging the ground material through the outlet (22), characterized in that,

a pulp lifter element (1) according to any of claims 1-9 and/or a pulp lifter (2) according to any of claims 10-13 arranged between the grate and the discharger for guiding ground material from the cylindrical housing to the discharger (24).

15. A grinding mill (3) according to claim 14, characterized in that the blades (6) extend to the discharger (24).

16. A grinding mill (3) according to claim 15, characterized in that at least a part of the guide surface (25) of the discharger part of the blade (6) is also angled in relation to the inner surface of the discharger wall (26).

17. A grinding mill (3) according to any of the claims 14-16, characterized in that the grate (23) comprises at least one grate lifter (27) arranged on the inside of the cylindrical housing of the grate (23) for guiding particles of ground material into the pulp lifter (2) through openings in the grate (23), and that the outer edge (28) of the grate lifter guide surface (30) is angled in relation to the grate wall (29) facing the inside of the cylindrical housing (20) such that the angle (a) between the grate wall (29) and the grate lifter guide surface (30) is smaller than 90 degrees at least at the outer edge of the grate lifter (27).

18. A grinding mill according to claim 14, characterized in that the grinding mill comprises a wet grinding mill and comprises at least one inlet for receiving a continuously fed process liquid.

19. A grinding mill according to claim 14, characterized in that the grinding mill comprises at least one of the following: grate discharge ball mills, SAG mills, and AG mills.