BR-112023014880-B1 - Discharge grate for an internal discharge end of a mill, method for coating a surface of said internal discharge end, and ore crushing method.

BR112023014880B1BR 112023014880 B1BR112023014880 B1BR 112023014880B1BR-112023014880-B1

Abstract

MILL DISCHARGE GRATE HAVING DYNAMIC VARIABLE SCREEN OPENINGS. This is a discharge grate (200) for an internal discharge end (3) of a mill (1) that can be characterized by having at least one dynamic variable screen opening (206) defined between two adjacent floating grate bars (202). The floating grate bars (202) can be configured to move, at least temporarily, relative to each other and/or relative to a retaining frame (201) that receives the floating grate bars (202). The temporary expansion of at least one dynamic variable screen opening (206) can allow undersized media to pass into the discharge chute (8) and reduce or eliminate the connection.

Inventors

Mauricio Salinas Hudson

Assignees

FLSMIDTH A/S

Dates

Publication Date: 20260310
Application Date: 20220125
Priority Date: 20210125

Claims (15)

1. Discharge grate (200) for an internal discharge end (3) of a mill (1), wherein the discharge grate (200) comprises an open surface area for the passage of pulverized material (5) from the interior of the mill (1) to a discharge chute (8) and a closed area to prevent the passage of grinding media (4) from the mill (1) and to keep the grinding media (4) and non-pulverized material inside the mill (1), wherein the discharge grate (200) is further characterized by comprising at least one dynamic variable sieve opening (206) defined between two adjacent floating grate bars (202), wherein said floating grate bars (202) are configured to move at least temporarily relative to each other and/or relative to a retaining frame (201) that receives the floating grate bars (202).
2. Discharge grid (200), according to claim 1, characterized by further comprising a resilient member (213) between each of the floating grid bars (202) and the retaining frame (201), wherein the resilient member (213) comprises a material that is configured to deform elastically.
3. Discharge grate (200), according to claim 2, characterized in that the material comprises a polymeric material.
4. Discharge grate (200), according to any of the preceding claims, characterized in that the retaining structure (201) comprises receiving openings (214) for receiving floating grate bars (202), wherein the receiving openings (214) are dimensioned larger than the floating grate bars (202) and configured to receive a resilient member (213).
5. Discharge grate (200), according to claim 4, characterized in that each of the receiving openings (214) comprises a first cutout (214d) and a second cutout (214e) positioned transversely to the first cutout (214d).
6. Discharge grid (200), according to claim 5, characterized in that each of the floating grid bars (202) comprises a first cutout (202d) and a second cutout (202e) positioned opposite the first cutout (202d), wherein at least one dynamic cutout of the variable screen opening (206) is defined between a first cutout (202d) of one of the floating grid bars (202) and a first cutout (214d) of one of the receiving openings (214).
7. Discharge grate (200), according to any of the preceding claims, characterized by further comprising an elevator (203).
8. Discharge grate (200), according to claim 7, characterized by further comprising a channel (211) for receiving a protrusion (218) from the elevator (203).
9. Discharge grate (200), according to any of the preceding claims, characterized by further comprising at least one transverse fixing bar (205) extending through the floating grate bars (202).
10. Discharge grate (200), according to claim 9, characterized in that at least one transverse fixing bar (205) is fixed by two lateral supports (212).
11. Discharge grate (200), according to any of the preceding claims, characterized by further comprising a base plate (207) supporting a base portion (204).
12. Discharge grate (200), according to claim 11, characterized in that the base plate (207) comprises a large passage opening (215) below the floating grate bars (202).
13. Discharge grate (200), according to any of the preceding claims, characterized by further comprising a recessed support rim (210) on opposite sides of a base portion (204) for supporting an elevator (203).
14. Method for coating an internal discharge end surface (3) of a mill (1) suitable for ore crushing characterized by comprising: providing the discharge grate (200), as defined in any of the preceding claims; mounting the discharge grate (200) on a discharge chute (8) of the mill (1); attaching the discharge grate (200) to a mounting (7) provided at the discharge end (3).
15. Ore crushing method characterized by comprising: providing a mill (1) suitable for crushing ore and having a discharge grate (200), as defined in any one of claims 1 to 13, providing an internal discharge end surface (3) of the mill (1); the discharge grate (200) being attached to an assembly (7) and extending over a discharge chute (8); filling the mill (1) with media (4) and material to be pulverized; operating the mill (1) by rotating a portion thereof containing the media (4) and the material to be pulverized; and allowing at least one dynamic variable sieve opening (206) to expand to allow pulverized material (5) and/or undersized media (4) to pass through thereto.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a single discharge grate 200 for use within a discharge end 3 of a mill 1. The discharge grate 200 comprises a series of movable (i.e., "floating") grate bars 202, which allow the dynamically variable sieve openings 206 of the discharge grate 200 to dynamically expand and contract as needed to accommodate the passage of the medium 4 and pulverized material 5 to a discharge chute 8 while preventing clogging occurrences. BACKGROUND OF THE INVENTION [0002] Reference to the background of the technique in this document should not be interpreted as an admission that such technique constitutes common general knowledge in the arts. [0003] Referring back to Figures 1-5, discharge grates 2 have been known to be used within the discharge ends 3 of mills 1 (e.g., SAG mills, ball mills, rod mills) for decades. During grinding operations, undersized media 4 can become trapped in the fixed sieve openings 6. Due to heat, pressure, and/or force, the media 4 can become trapped or welded into the sieve openings 6 (as suggested in Figure 4). The lodged media 4 reduces the total open area of the discharge grate 2 defined by the fixed sieve openings, thus leading to greater occlusion of the fixed sieve openings by the pulverized material. Eventually, the open area of the discharge grates 2 can become so reduced that the discharge grates 2 must be removed and replaced. Therefore, it is a long-felt need to provide a more robust and bond-resistant mill discharge grate 2 design. [0004] Figure 1 represents a discharge end 3 of a mill 1 immediately after regrinding (photo taken from inside mill 1), where the conventional discharge screens 2 have recently been replaced. It can be seen from this Figure that very little binding and/or occlusion is present in the discharge screens 2 and that the flow of pulverized material 5 is quite free to flow through the fixed sieve openings 6. [0005] Figure 2 depicts a discharge end 3 of a mill 1 shortly after decommissioning (photo taken from inside mill 1), where the conventional discharge grates 2 have become bonded/occluded and need to be replaced. In particular, one of the discharge grates 2 and the lifting bars 9 have been removed from a support 7, thus exposing a discharge channel 8 below. It can be seen in this Figure that a significant amount of bonding by the medium 4 and/or occlusion by the pulverized material 5 is present in the discharge grates 2. Thus, a flow of pulverized material 5 through the discharge grates 2 and into the discharge chute is significantly impaired due to the reduction in the open area of the fixed screen openings 6. Figure 3 shows a foreground portion of Figure 3. [0006] The present invention aims to improve existing mill discharge grate devices that incorporate movable, i.e., "floating" grate bars that can temporarily expand to allow the passage of medium 4 and/or pulverized material 5, in turn leading to improved performance, reduced binding, greater flexibility and modularity. OBJECTIVES OF THE INVENTION [0007] It is an object of the embodiments of the invention to provide an improved discharge grate 2 for a mill 1 that overcomes or improves one or more of the disadvantages or problems described above, or that at least provides a useful alternative to the conventional discharge grate apparatus. [0008] A particular objective of the embodiments is to provide a discharge screen 2 that exhibits improved service life, reduced bonding occurrences, reduced screen opening occlusion rate and improved screening performance compared to conventional discharge screens 2. [0009] Other preferred objectives of the present invention will become apparent from the description that follows. SUMMARY OF THE INVENTION [0010] The embodiments of the dynamic variable opening discharge door (200) are disclosed. [0011] A discharge grate (200) for an internal discharge end (3) of a mill (1) may comprise an open surface area for the passage of pulverized material (5) from the interior of the mill (1) to a discharge chute (8). The discharge grate (200) may further comprise a closed area to prevent the passage of the grinding medium (4) from the mill (1). The closed area may help to keep the grinding medium (4) and the unpulverized material inside the mill (1). The discharge grate (200) may be characterized in that it may further comprise at least one dynamic variable screen opening (206). The dynamic variable screen opening (206) may be defined between two adjacent floating screen bars (202). The floating screen bars (202) may be configured to move, at least temporarily, relative to each other and/or relative to a retaining frame (201) that receives the floating screen bars (202). [0012] According to some embodiments, the discharge grid (200) may comprise a resilient member (213). The resilient member may be positioned between each of the floating grid bars (202) and the retaining frame (201), without limitation. The resilient memb