A ROLL FOR A ROLLER PRESS, AS WELL AS A ROLLER PRESS PROVIDED WITH SUCH A ROLL

Abstract

The invention relates to a roll for a roller press suitable for comminution of granular material by interparticle crushing, as well as a roller press provided with such a roll. In certain applications and under specific operational conditions the autogenous layer starts to displace or flow between the outwardly extending wear-resistant surface studs. This flow of granular material has a low velocity relative to the roll and can cause excessive wear to the base material of the outer cylindrical pressing surface of the roll, instead of protecting it.

Claims

1. A roll for a roller press suitable for comminution of granular material by interparticle crushing, said roll comprising: a cylindrical body having an outer cylindrical pressing surface for use with an opposing roll in an interparticle crushing pressing nip; a plurality of outwardly extending wear-resistant surface studs positioned on the pressing surface; wherein the cylindrical body is provided with means for restricting the flow of granular material between the outwardly extending wear-resistant surface studs along the outer cylindrical pressing surface.

2. A roll according to claim 1, wherein the flow restricting means are fitted at positions on the pressing surface, where the possibility of flow of granular material in a rotational direction along the outer cylindrical pressing surface exists.

3. A roll according to claim 1, wherein the flow restricting means are fitted at positions on the pressing surface, where the possibility of flow of granular material in a longitudinal direction along the outer cylindrical pressing surface exists.

4. A roll according to claim 1, wherein the flow restricting means extends in a longitudinal direction along the outer cylindrical pressing surface.

5. A roll according to claim 1, wherein the flow restricting means extends in a rotational direction along the outer cylindrical pressing surface.

6. A roll according to claim 1, wherein the plurality of outwardly extending wear-resistant surface studs are positioned in a pattern consisting of parallel extending lines on the pressing surface and wherein the flow restricting means are provided between adjacent pattern lines.

7. A roll according to claim 1, wherein the flow restriction means are made of one or more strip-like elements provided on the outer cylindrical pressing surface of the cylindrical body.

8. A roll according to claim 7, wherein the strip-like flow restriction means are composed of a first strip-like element positioned in a longitudinal direction on the outer cylindrical pressing surface of the cylindrical body and at least a further strip-like element positioned at an inclined orientation relative to the first strip-like element.

9. A roll according to claim 7, wherein the strip-like flow restriction means are composed of a series of strip-like elements positioned in a zig-zag orientation on the outer cylindrical pressing surface of the cylindrical body.

10. A roll according to claim 1, wherein the wear-resistant surface studs are made from a material being harder than the material of the outer cylindrical pressing surface.

11. A roll according to claim 1, wherein the flow restricting means are made from a hard metal mixture, e.g. Tungsten Carbide based mixtures.

12. A roller press suitable for comminution of granular material by interparticle crushing, said roller press comprising: at least one set of two opposing rolls, each roll consisting of a cylindrical body having an outer cylindrical pressing surface for use with the opposing roll in an interparticle crushing pressing nip; wherein at least one roll is provided with means for restricting the flow of granular material between the outwardly extending wear-resistant surface studs along the outer cylindrical pressing surface according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention will now be described in more details in reference to accompanying drawings, which drawings show in:

[0019] FIG. 1 a schematic embodiment of a roller press consisting of a set of two opposing rolls according to the state of the art;

[0020] FIG. 2 a schematic cross sectional detail of the roll of FIG. 1;

[0021] FIG. 3 a schematic detail of the flow of the autogenous layer of granular material across the cylindrical surface of the roll of FIG. 1;

[0022] FIG. 4 a first embodiment of a roll provided with flow restriction means according to the invention;

[0023] FIG. 5 a second embodiment of a roll provided with flow restriction means according to the invention;

[0024] FIG. 6 a third embodiment of a roll provided with flow restriction means according to the invention;

[0025] FIG. 7 a schematic cross sectional detail of the roll of FIG. 4;

DETAILED DESCRIPTION OF THE INVENTION

[0026] For a better understanding of the invention like parts in the drawings are be denoted with like reference numerals.

[0027] FIG. 1 depicts in a schematic manner a roller press 1 suitable for comminution of granular material by interparticle crushing according to the state of the art. Such a roller press 1 is to be used for comminution or grinding of granular material by interparticle crushing and is composed of a set of two opposing rolls or rollers 10 and 20 respectively. Each roll 10-20 is composed of a cylindrical body having a longitudinal length dimension x and having an outer cylindrical pressing surface 11-21 and side faces 10b-20b.

[0028] Each roll 10-20 can be rotated around their longitudinal axis of rotation 10a-20a using suitable (non-depicted) roll driving means. For a proper operation of the roller press 1, both rolls 10-20 of the set of rolls are rotated in opposite rotational directions, as shown by the rotational arrows y and y on the left of FIG. 1.

[0029] Both rolls 10-20 are orientated parallel from each other in their longitudinal orientation and at some distance from each other, as shown in FIG. 1. The distanced orientation as shown in FIG. 1 creates a space between the two opposing outer cylindrical pressing surfaces 11-21 of both cylindrical bodies, which space is denoted with reference numeral 30 and also indicated as an interparticle crushing pressing nip.

[0030] During operation of the roller press granular material, which for example is being processed in the mining or cement/mortar industry, is fed into the nip 30 between the two opposing rotatable rollers 10-20, which are rotating in opposite directions y and y. Under friction the granular material is compressed between the roller surfaces 11-21 with the application of extremely high pressures, thereby reducing the solid materials to a smaller average particle size.

[0031] During this type of mineral processing, the outer cylindrical pressing surfaces 11-21 of each roll 10-20 are exposed to extraordinarily high stressing and high wear. An improvement which has been done is to armor the roller surfaces 11-21 with a wear-resistant cladding (not shown) to provide a hardened outer surface.

[0032] In addition, in order to improve the draw-in capability of the pressing rollers 10-20 that must draw the granular material product into the nip 30 by friction and compress it, it is known to provide the outer cylindrical pressing surface 11-21 of each counter-rotating roll 10-20 with a plurality of outwardly extending wear-resistant surface studs 12-22. Usually the outwardly extending wear-resistant surface studs 12-22 are made from a material being harder than the material of the outer cylindrical pressing surface 11-21 and the studs 12-22 extends at a height h of approx. 5-10 mm from the surface 11-21.

[0033] The granular material being drawn-in and captured in the spaces 13-23 between the studs 12-22 forms an autogenous layer 40, which provides a protecting layer for the outer cylindrical pressing surface 11-22 of the roll 10-20. See FIG. 2. Herewith the lifespan of the roll 10-20 is extended and the comminution of granular material by interparticle crushing is improved.

[0034] However, in certain applications and under specific operational conditions the autogenous layer 40 starts to displace or flow in the spaces 13-23 between the outwardly extending wear-resistant surface studs 12-22. This flow of granular material is depicted in FIG. 3 with arrows 40a and 40b and is opposite to the direction of rotation (y or y) of the respective roll (10 or 20).

[0035] In this example FIG. 3 depicts roll 20 of the roller press of FIG. 1, and as such flow arrows 40a denote an autogenous material flow in rotational direction opposite to the rotational direction y of the roll 20 around its longitudinal axis 20a across the outer cylindrical pressing surface 22 of the roll 20, whereas flow arrows 40b denote an autogenous material flow in a (more or less skewed) longitudinal direction x across the outer cylindrical pressing surface 11-22 of the roll 10-20 in the direction x (or its opposite direction x) of the side faces 10b-20b of the roll 10-20.

[0036] The autogenous material flows 40a-40b exhibit a low velocity relative to the roll surface 11-22 and can cause excessive wear to the base material of the outer cylindrical pressing surface 11-22 of the roll 10-20, instead of protecting it. This autogenous layer flow 40a-40b thus limits the life span of the roll 10-20 and the roller press 1 significantly, but also disrupts the comminution of the granular material by interparticle crushing in the nip 30 between the opposing rolls 10-20.

[0037] As a solution for the above described phenomenon of autogenous layer flow FIG. 4 depicts an example of a roll 10-20 according to the invention. In this Figure roll 20 is depicted as can be observed from its rotational direction y (see also FIG. 1). The cylindrical body of the roll 10-20 is provided with means 50 for restricting the flow of granular material in the spaces 13-23 between the outwardly extending wear-resistant surface studs 12-22 along the outer cylindrical pressing surface 11-21.

[0038] In particular the flow restricting means 50 are fitted at positions on the pressing surface 11-21, where the possibility of flow 40a of granular material in a rotational direction opposite the rotational direction y of the roll 10-20 along the outer cylindrical pressing surface 11-21 exists, whereas in another example the flow restricting means 50 are fitted at positions on the pressing surface 11-21, where the possibility of flow 40b of granular material in a longitudinal direction x (or x) along the outer cylindrical pressing surface 11-21 exists.

[0039] Embodiments of these example are shown in FIGS. 4-5-6. In FIG. 4 the plurality of outwardly extending wear-resistant surface studs 12-22 are positioned in a pattern consisting of parallel extending pattern lines i1-i2-i3-i4-i5-etc.-etc. on the pressing surface 11-21 and the flow restricting means 50 are provided between adjacent pattern lines, here between pattern lines i1 and i2 and between pattern lines i4 and i5. See also FIG. 7.

[0040] In this the design the flow restriction means are made of one or more strip-like elements 50 provided on the outer cylindrical pressing surface 11-21 of the cylindrical body of the roll 10-20. In particular the strip-like flow restriction means 50 are composed of assembly-strip consisting of a first strip-like element 50a1-50a2-etc.-etc. positioned in a longitudinal direction x on the outer cylindrical pressing surface 11-21 of the cylindrical body (of the roll 10-20) and at least a further strip-like element 50b1-50b2-50b3-etc.-etc. positioned at an inclined orientation relative to the first strip-like element 50a1-50a2-etc.-etc. Both the first strip-like element 50a1-50a2-etc.-etc. and the at least further strip-like element 50b1-50b2-50b3-etc.-etc. are interconnected or converge at their connections 50c1-50c2-etc.-etc. With this example any damaging, erosive flow of the autogenous layer 40 of granular layer in a rotational direction y (flow arrow 40a) as well as in a (more or less) longitudinal direction x (flow arrow 40b) towards the side faces 10b-20b of the roll 10-20 along the circumference (seen in rotational or longitudinal direction) of the outer cylindrical pressing surface 11-21 is prevented.

[0041] Another advantageous example is shown in FIG. 6, wherein the strip-like flow restriction means 50 are composed of a series of strip-like elements 50d1-50d2 positioned in a zig-zag orientation between the outwardly extending wear-resistant surface studs 12-22 on the outer cylindrical pressing surface 11-21 of the cylindrical body. This example of the flow restriction means 50d1 is in particular useful for application on the outer cylindrical pressing surface 11-21 of the roll 10-20 having a more dense or an irregular pattern of outwardly extending wear-resistant surface studs 12-22. Also in this example the pattern of outwardly extending wear-resistant surface studs 12-22 is composed of closely positioned pattern lines i1-i2-i3-i4-i5-i6-etc.-etc., with the zig-zag orientated strip-like elements 50d1-50d2 being positioned between pattern lines i1-i2 and i5-i6.

[0042] With the examples above excessive wear to the base material of the outer cylindrical pressing surface 11-21 of the roll 10-20 is significantly reduced or even prevented, as well as the comminution of the granular material by interparticle crushing in the nip 30 between the opposing rolls 10-20 is no longer disrupted. Furthermore the autogenous layer 40 of granular material present in the spaces 13-23 between the outwardly extending wear-resistant surface studs 12-22 is prevented to fluidize because of the presence of the flow restricting means 50 (50a1-50a2-etc.; 50b1-50b2-etc.; 50d1-50d2-etc.), thus preventing erosive flow 40a-40b and excessive wear to the base material of the outer cylindrical pressing surface of the roll 10-20.

[0043] Preferably, the flow restricting means can be made from a hard metal mixture, e.g. Tungsten Carbide based mixtures.

LIST OF REFERENCE NUMERALS

[0044] 1 Roller press [0045] 10/20 First/second roll of set of rollers [0046] 10a/20a Axis of rotation [0047] 10b/20b Side face of cylindrical body of roll [0048] 11/21 Outer cylindrical pressing surface of cylindrical body [0049] 12/22 Outwardly extending wear-resistant surface stud [0050] 13/23 Space between adjacent outwardly extending wear-resistant surface studs [0051] 30 Nip between first and second roll [0052] 40 Autogenous layer of granular material [0053] 40a Flow of granular material between the surface studs in circumferential direction [0054] 40b Flow of granular material between the surface studs in longitudinal direction (in the direction of the side faces) [0055] 50 Means for restricting the flow of granular material (first embodiment) [0056] 50a1-2 first strip element of flow restriction means (second embodiment) [0057] 50b1-2-3 Second strip element of flow restriction means (second embodiment) [0058] 50c1-c2 Interconnection between first and second strip-elements [0059] i1-i2-etc. pattern lines of studs on the pressing surface