Multi-Layer Lifter For Semi-Autogenous Mills Or Sag Mills

Abstract

The invention relates to a multi-layer lifter for semi-autogenous mills or SAG mills with improved durability, made up of: a base formed by a body having a rectangular cross-section, which has a first straight side wall and a second angled side wall; where an angled rectangular portion emerges from the upper half of said angled wall, in which a trapezoidal projection emerges from the lower portion of said base, to fit with the coatings or liners of the inside of the mill; a multi-laminated spring portion which is made up of a plurality of convex curved sheets and a bent straight portion that is located under the angled rectangular portion of said base; and a hollowed-out rubber body, located in the cavity formed by the base and the convex curved sheets.

Claims

1. A multi-layer lifter (1) for semi-autogenous mills or SAG mills with improved durability, CHARACTERIZED in that it is made up of: a base (3) formed by a body having a rectangular cross-section (4), which has a first straight side wall (5) and a second angled side wall (6); where an angled rectangular portion (7) emerges from the upper half of said angled wall (6), in which a trapezoidal projection (8) emerges from the lower portion of said base (3) to fit with the coatings or liners (12) of the inside of the mill; a multi-laminar spring portion (9) that is made up of a multiplicity of curved convex sheets (10) and a bent straight portion (11) which is located under the rectangular angled portion (7) of said base (3); and a hollow rubber body (2), located in the cavity formed by the base (3) and the convex curved sheets (10), which deforms when the multiplicity of sheets is compressed as a result of the force generated by the balls (15) and ore inside the mill.

2. A multi-layer lifter (1) according to claim 1, CHARACTERIZED in that the base (3) has at least one perforation to join the multilayer lifter (1) to the mill drum (18).

3. A multi-layer lifter (1) according to claim 1, CHARACTERIZED in that the lifters are placed side by side, thus forming a continuous line in the form of a lifter bar from the inlet of the mill to the outlet.

4. A method of operation of the multilayer lifter (1) for semi-autogenous mills or SAG mills with improved durability, CHARACTERIZED in that it comprises the stages of: (a) compressing in the lower part (19) of the kidney (16) a plurality of multilayer lifters (1) having a multi-laminar spring portion (9) with curved convex sheets (10) over a hollow rubber body; and (b) decompressing in the upper part (20) of the kidney (16) said plurality of multilayer lifters (1) by driving the balls and ore towards the center of the mill.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide further understanding of the invention, and are a part of this description and show one of the preferred embodiments.

[0019] FIG. 1 shows a perspective view of the multi-laminar lifter of the present invention.

[0020] FIG. 2 shows a perspective view of the multi-laminar lifter with the elastomeric core of the present invention.

[0021] FIG. 3 shows a perspective view of the interior of a mill, where the multi-laminar lifter of the present invention is installed.

[0022] FIG. 4 shows a perspective view of the interior of a mill, where a plurality of multi-laminar lifters of the present invention is installed.

[0023] FIG. 5 shows a perspective view of a row of multi-laminar lifters of the present invention.

[0024] FIG. 6 shows a perspective view with an uncompressed multi-laminar lifter and another multi-laminar lifter compressed by a ball to accumulate energy.

[0025] FIG. 7 shows a perspective view of one of a SAG mill of the prior art, showing the ore kidney shape and balls with flattened shape.

[0026] FIG. 8 shows a cross-sectional view of a SAG mill, showing the ore kidney and balls with the multi-laminar lifters being compressed in the lower part and releasing energy with the ball drive and ore on the upper part of said kidney.

[0027] FIG. 9 shows a cross-sectional view of a SAG mill, showing the ore kidney and balls, with the multi-laminar lifters being compressed in the lower part and highlighting the energy release with the ball drive and ore on the upper part of said kidney.

DESCRIPTION OF THE INVENTION

[0028] The present invention refers to a lifter bar, or lifter, for semi-autogenous mills, which consists of multiple sheets acting as a spring that accumulates energy in the lower part of the mill and then releases it by pushing the balls and the milling ore in the upper part as the mill rotates.

[0029] With reference to FIGS. 1-5, a perspective of the multi-layer lifter (1), as well as a portion of the SAG mill that has said multi-layer lifter (1) installed, which consists of a base (3) and a multi-laminar spring (9), consisting of the multiple layers that act as a package spring and that are worn down in layers as its use progresses, is shown.

[0030] The base (3) consists of a body with a rectangular cross section (4), which has a first straight sidewall (5) and a second angled sidewall (6). From the upper half of said angled wall (6), a rectangular angled portion (7), which has the function of fastening the multiple convex sheets (10) of the straight portion (11) of the multi-laminar spring (9) of the multi-layer lifter (1), arises. From the lower part of the base (3), a trapezoidal projection (8), which fits with the liners (12) inside the mill, thus forming one next to the other inside the mill a trapezoidal cavity (13) so that said trapezoidal projection (8) is fitted, emerges as shown in FIGS. 3 and 4. The base (3) has at least one perforation to join the multi-layer lifter (1) to the mill drum (18). The lifters are placed side by side (as shown in FIG. 5), thus forming a continuous line from the inlet of the mill material to the sorting grills (14), where the material is discharged according to the ore size and the grooves of said grill (see FIGS. 3 and 4).

[0031] The multi-laminar spring portion (9) is made up of a multiplicity of curved convex sheets (10) and a bent straight portion (11) which is located under the rectangular angled portion (7) of the base (3), which are joined by bolts and nuts (14). Thus, the multi-laminar spring portion (9) consists of a curved convex portion and a bent straight portion, wherein the latter fits under the angled rectangular portion (7) of the base (3).

[0032] The metallic portion, consisting of the base (3) and the curved convex portion of the multi-laminar spring (9), leave a recess that is filled by a hollow rubber body (2), which deforms when the multiplicity of sheets is compressed as a result of the force generated by the ore and the balls (15), as shown in FIG. 6. Indeed, this figure allows to noting the deformation suffered by the hollow rubber body (2) and the curved convex sheets (10) of the multi-laminar spring (9) caused by the weight of the balls (15) and the ore. In addition, the hollow rubber body (2) has the function of filling the void left by the metal portions of the base (3) and the curved convex sheets (10) of the multi-laminar spring (9), thus preventing it from being filled with balls and ore.

[0033] FIGS. 7-9 show the effect produced by the multi-layer lifter (1) as the mill rotates.

[0034] FIG. 7 of the prior art shows a mill inside of which there is a plurality of trapezoidal lifters (17), where, as the mill turns, the ore and balls (15) are lifted by them and a kidney of material (16) is generated.

[0035] FIGS. 8 and 9 show how the column of balls on the multi-layer lifter (1) generates a compression force F. In FIG. 8, the size of the arrow indicates the magnitude of the force F that is generated in the kidney (16) and that crushes the multi-layer lifters (1), thus initiating the compression of the curved convex blades (10) of the multi-laminar spring (9). In the first lower portion (19) of the kidney (16), the force F is observed to be higher on the multi-layer lifter (1) and decreases as the mill turns. Towards the part of the upper part (20) of the kidney (16), the force is lower, but the curved convex blades (10) of the multi-laminar spring (9) begin to decompress. The difference in strength between one side of the kidney and the other is the force accumulated by the multi-layer lifter (1) to release it as a pulse on the upper part (20) of the kidney (16), thus causing the balls (15) and ore to be propelled towards the center of the mill, as shown in FIG. 9.

[0036] According to the above, it is possible to provide the following method of operation of the multi-layer lifter (1):

[0037] (a) compressing in the lower part (19) of the kidney (16) a plurality of multi-layer lifters (1) having a multi-laminar spring portion (9) with curved convex sheets (10);

[0038] (b) decompressing in the upper part (20) of the kidney (16) said plurality of multi-layer lifters (1) by driving the balls and ore towards the center of the mill; and

[0039] (c) repeat the process as the mill rotates.