Trommel

Abstract

To provide a trommel which can elongate a life of a screen while maintaining classification performance of nickel raw material ore with a simple constitution.SOLUTION: A trommel 100 is provided with a truncated cone cylindrical or a cylindrical screen 110 which is connected with a drum provided on a drum washer and can be rotated around an axial core as a center. The screen 110 has the introduction side 30 to which an object to be classified is introduced and a discharge side 40 from which the object to be classified remaining after classification is discharged. The screen 110 includes a metallic grating 111 on the introduction side 30 and, at a tip of the discharge side 40 of the metallic grating 111, two layers of expand metal 112 are provided so as to further be extended from the discharge side 40.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a trommel, and more particularly to a trommel attached to a drum washer for screening nickel raw ore for use in an HPAL plant. [Background technology]

[0002] In recent years, high pressure acid leaching using sulfuric acid has been attracting attention as a method for hydrometallurgy of nickel oxide ore. Unlike the conventional dry smelting method for nickel oxide ore, this method does not include dry processes such as reduction and drying, but consists of a continuous wet process, which is advantageous in terms of energy and cost. Another advantage is that it is possible to obtain nickel-containing sulfides (hereinafter also referred to as "nickel sulfides") with nickel content improved to about 50 mass%.

[0003] In HPAL plants that use low-grade nickel ore, the raw material nickel ore is transported and supplied from the mine. This contains large-sized ore, which becomes an obstacle when transporting it with a pump, etc. In addition, the nickel content of large-sized ore is low, and leaching only occurs on the surface of the ore, so the leaching rate is low and it needs to be removed. For this reason, in the nickel raw material preparation process that prepares the nickel raw ore for the HPAL plant, washing and screening equipment are installed to remove the large-sized ore.

[0004] As a washing and screening device, a drum washer consisting of a drum and a trommel is used to remove large-sized ores. Drum washers are also widely used for washing waste materials. A trommel is a device equipped with a truncated cone-shaped or cylindrical screen that is installed horizontally (with the axis horizontal or inclined to a position close to horizontal), and performs a classification process (a process of separating objects of various sizes according to their size) of the objects to be classified that are put into the screen by rotating the screen around the axis. One of the uses of such a trommel is the classification process of nickel oxide ore.

[0005] For example, Patent Document 1 proposes a protrusion that satisfies certain requirements on the same circumference of a vertical cross section of the inner surface of a trommel relative to the trommel rotation axis in order to prevent a significant decrease in efficiency when crushing and classifying nickel raw ore to be prepared.

[0006] However, when the trommel described in Patent Document 1 is used in an HPAL plant, large-sized ores contained in the ore slurry are lifted up by the discharge or rotation of the drum, and the large-sized ores drop during the rotation, causing the impact of the large-sized ores on the screen of the trommel, which wears or breaks the screen, requiring repairs during operation. Repairs during operation may affect the availability of downstream equipment and may also reduce production efficiency.

[0007] The applicant has previously proposed in Patent Document 2 a trommel that is connected to a drum of a drum washer and is provided with a cylindrical screen that is rotatable around an axis, the screen having a lattice-shaped metal grating that extends along the axis from the connection with the drum, and a lattice-shaped resin screen that extends along the axis at the tip of the extending metal grating.

[0008] In one embodiment of such a trommel, the trommel is divided into three sections along its length, with a metal grating used for the first section and a combination of a urethane screen and a punched plate used for the second and third sections as the screen. This has successfully extended the lifespan of the screen, shortening the time required for the first emergency repair from the previous two to four months to four to six months. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2009-173967 A [Patent Document 2] JP 2018-183726 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, because the regular maintenance cycle for HPAL plants is every six months, emergency repairs would be necessary while the HPAL plant was in operation, which was a factor in reducing production volume, even if the screen's lifespan was extended to four to six months using the technology in Patent Document 2. In addition, resin screens such as urethane screens are relatively expensive and take time to obtain.

[0011] In view of the above, the present invention has been proposed, and has an object to provide a new and improved trommel that can further extend the life of the screen with a simple structure while maintaining the screening performance of the nickel raw ore. [Means for solving the problem]

[0012] That is, in order to achieve the above-mentioned object, one aspect of the present invention is a trommel provided with a truncated conical or cylindrical screen that is connected to a drum of a drum washer and can rotate around an axis, the screen having an introduction side into which the material to be classified is introduced and a discharge side from which the material to be classified remaining after classification is discharged, the screen is provided with a metal grating on the introduction side, and two layers of expanded metal are provided at the tip of the discharge side of the metal grating so as to extend further from the discharge side.

[0013] According to one aspect of the present invention, by forming two layers of expanded metal and extending them from the tip of a metal grating, it is possible to further extend the life of the screen with a simple configuration.

[0014] In this case, in one aspect of the present invention, the two-layer expanded metal may be two sheets of the same kind of expanded metal stacked on top of each other.

[0015] By stacking two sheets of the same type of expanded metal, even if the inner expanded metal develops a hole, the outer expanded metal will continue to function, eliminating the need for emergency repairs.

[0016] In one embodiment of the present invention, the two layers of expanded metal may be stacked so that the holes of the two layers are in the same position.

[0017] In this way, the decrease in screen efficiency can be minimized.

[0018] In one embodiment of the present invention, the metal grating and the two layers of expanded metal may be connected to be flush with each other on the inside of the screen.

[0019] In this way, the material to be classified (ore) can be smoothly transported from the metal grating to the two layers of expanded metal.

[0020] In one embodiment of the present invention, the metal grating may extend in the range of 0.3 to 0.4 times the length of the screen in the axial direction.

[0021] In this way, large-sized ore transferred from the drum can fall onto the metal grating.

[0022] In addition, in one aspect of the present invention, the thickness of the metal grating may be 5 mm or more.

[0023] By setting the thickness of the metal grating within the above range, the metal grating becomes sturdy and its lifespan can be extended, and it also becomes easy to visually check the progress of wear.

[0024] In addition, in one aspect of the present invention, the metal grating may be configured to be divided into multiple pieces.

[0025] In this way, it is not necessary to replace the entire metal grating during repairs, but rather only the portion corresponding to the damaged area can be replaced.

[0026] Also, in one aspect of the invention, the drum washer may be used to screen nickel raw ores in a hydrometallurgical plant.

[0027] A trommel according to one embodiment of the present invention is preferably applied to a drum washer for screening nickel raw material ore used in an HPAL plant. Effect of the Invention

[0028] According to the present invention, it is possible to further extend the life of the screen with a simple structure while maintaining the screening performance for nickel raw ore. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a process diagram of a hydrometallurgical method for nickel oxide ore by high-pressure acid leaching. [Diagram 2] FIG. 2 is a schematic diagram of a drum washer. [Diagram 3] FIG. 3(A) is a schematic explanatory diagram of a trommel according to one embodiment of the present invention, and FIG. 3(B) is an enlarged cross-sectional view of a bottom portion of the trommel according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram of a trommel according to another embodiment of the present invention. [Diagram 5] Figures 5(A) to (C) are schematic diagrams illustrating the wear and breakage conditions when only one layer of expanded metal is used, and Figures 5(D) and (E) are schematic diagrams illustrating the effect of using two layers of expanded metal in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] A preferred embodiment of the present invention will be described in detail below. Note that the embodiment described below does not unduly limit the content of the present invention described in the claims, and all of the configurations described in the embodiment are not necessarily essential as the solution of the present invention.

[0031] [1. Overview] The trommel according to one embodiment of the present invention is used in conjunction with a drum washer that sieves nickel raw ore in a method for hydrometallurgy of nickel oxide ore. The hydrometallurgy process of nickel oxide ore is a smelting process in which nickel is leached from nickel oxide ore and recovered using, for example, a high-pressure acid leaching method (HPAL method). Note that the trommel according to one embodiment of the present invention is not necessarily limited to classification in the hydrometallurgy method of nickel oxide ore, and may be used as a general rotary sieve device for classification of objects to be classified other than nickel oxide ore.

[0032] Fig. 1 is a process diagram of a hydrometallurgical method by high-pressure acid leaching of nickel oxide ore. As shown in Fig. 1, the hydrometallurgical process of nickel oxide ore includes an ore slurrying step S1 for slurrying nickel oxide ore, an ore slurry concentrating step S2 for removing water contained in the ore slurry to concentrate the ore components, a leaching step S3 for adding sulfuric acid to the produced ore slurry and performing leaching treatment under high temperature and high pressure, a solid-liquid separation step S4 for separating the residue (leaching residue) while washing the obtained leaching slurry in multiple stages to obtain a leachate containing nickel and impurity elements, a neutralization step S5 for adding limestone as a neutralizing agent to the leachate to adjust the pH of the leachate, separating neutralized precipitate containing impurity elements, and obtaining a neutralized final solution containing nickel, and a sulfurization step S6 for generating a sulfide containing nickel (nickel sulfide) by adding a sulfurizing agent to the neutralized final solution.

[0033] Furthermore, this hydrometallurgical smelting method includes a final neutralization step S7 in which the leaching residue separated in the solid-liquid separation step S4 and the barren liquid discharged in the sulfidation step S6 are collected and rendered harmless. This final neutralization step S7 is a step-by-step neutralization process consisting of a first-stage neutralization process (first final neutralization step) using limestone as a neutralizing agent, and a second-stage neutralization process (second final neutralization step) using hydrated lime as a neutralizing agent. By carrying out this two-stage neutralization process, a neutralization residue is generated and stored in a tailings dam (tailings residue).

[0034] In the HPAL plant, a washing device is installed to remove large-sized ores in the process of obtaining an ore slurry from nickel raw ore in the ore slurrying step S1. The washing device has a function of separating the nickel raw ore so that the ore can be acid-leached in the above-mentioned leaching step S3. This washing device is composed of a drum washer (drum-type washer) and a sifter. The drum washer has a function of increasing the nickel grade in the ore slurry by washing the nickel raw ore with water.

[0035] Fig. 2 is a schematic explanatory diagram of a drum washer. As shown in Fig. 2, the drum washer 1 includes a drum 10 and a trommel 20, and a recovery blade 11 is provided on the side of the drum 10 connected to the trommel 20. The drum 10 has a function of crushing and repulping (loosening) nickel oxide ore to produce an ore slurry S. The recovery blade 11 has a function of scraping up the ore contained in the ore slurry S from inside the drum 10. The trommel 20 has a function of sieving the ore contained in the ore slurry S.

[0036] In the drum washer 1, water and nickel oxide ore are supplied from an inlet (not shown) provided on the inlet side (upstream side) of the drum 10, and the necessary nickel raw material ore is slurried with water from the large particle size ore inside the drum 10 and sent to the trommel 20, which is a large classification device, and the ore with a particle size of 25 mm or more contained in the ore slurry S is removed by the screen of this trommel 20. Furthermore, a sifter arranged below the screen of the trommel 20 removes ore with a particle size of 1.4 mm or more contained in the ore slurry S that has passed through the screen.

[0037] Therefore, a large classification device called a trommel 20 is installed on the outlet side (downstream side) of the drum 10 in order to separate the ore slurry S from the large-particle-size ore. The screen of this trommel 20 is in the shape of a truncated cone or cylinder, and the trommel 20 is connected to the drum 10 so that it can sieve the charged materials while rotating together with the drum 10.

[0038] The ore slurry S discharged from the drum 10 overflows from a weir (not shown) installed near the connection of the drum 10, and the ore contained in the ore slurry S is scooped up by a recovery blade 11 installed in the drum 10 and transferred to the trommel 20. Here, by providing the recovery blade 11 on the drum 10, the ore is scraped up from within the system of the drum 10, and the ore contained in the ore slurry is smoothly transferred from the drum 10 to the trommel 20. As a result, an ore slurry with a stable ore content can be obtained, and since large-sized ores are less likely to remain in the drum 10, wear of the drum 10 itself can be suppressed and the energy required to drive the drum 10 can be reduced.

[0039] However, when large-sized ores contained in the ore slurry S are transported to the trommel 20 by the recovery blades 11, the large-sized ores fall onto the screen of the trommel 20, causing a very large impact and causing noticeable wear and damage to the screen in a short period of time.

[0040] If the screen of the trommel 20 is damaged, large-sized ores are carried into the sieving machine in the downstream stage, increasing the load on the sieving machine and making the sieving machine more susceptible to damage. If the sieving machine is damaged, the large-sized ores will be clogged in the narrow parts of the pumps and valves and block the flow path of the ore slurry, and the equipment will have to be stopped for a long period of time to remove the blockage. In order to prevent damage to the sieving machine and clogging of the flow path, if the screen of the trommel 20 is found to be worn or damaged, it is necessary to stop the equipment even during operation of the HPAL plant and repair or replace the screen, which is a factor that reduces the availability rate of the equipment.

[0041] In order to prevent the screens from wearing or breaking, for example, all the screens can be provided with thick metal gratings. However, in exchange for ensuring the strength of the screens, the opening area for sieving is insufficient, so that the raw material ore slurry is excessively discharged outside the trommel 20 system, and the weight of the equipment increases, making operation difficult. On the other hand, if all the screens are made of plastic screens, although they have a certain degree of impact resistance and abrasion resistance, the strength of the plastic screens themselves is insufficient, so that the openings of the plastic screens gradually widen during operation, making it impossible to filter out ores larger than the desired particle size.

[0042] Therefore, the present inventors discovered that in order to maintain the screening performance of the screen of the trommel 20 attached to the drum washer 1 used when screening the nickel raw material ore used in the HPAL plant, the life of the trommel 20 can be further extended by providing a lattice-shaped metal grating around the periphery of the connection part with the drum 10 and providing two layers of expanded metal extending further outward from the tip of the metal grating, and thus completed the present invention.

[0043] [2. Trommel] Next, a trommel according to an embodiment of the present invention will be described with reference to the drawings. Fig. 3(A) is a schematic explanatory diagram of a trommel according to an embodiment of the present invention, and Fig. 3(B) is an enlarged cross-sectional view of the bottom surface of the trommel according to an embodiment of the present invention. One aspect of the present invention is a trommel 100 provided with a truncated cone-shaped or cylindrical screen 110 that is connected to a drum of a drum washer and can rotate around an axis. The screen 110 has an introduction side 30 where the objects to be classified are introduced and a discharge side 40 where the objects to be classified remaining after classification are discharged. The screen 110 has a metal grating 111 on the introduction side 30, and two layers of expanded metal 112 are provided at the tip of the discharge side 40 of the metal grating 111 so as to extend further from the discharge side 40.

[0044] As shown in Fig. 3(A), a trommel 100 according to an embodiment of the present invention is provided with a truncated cone-shaped screen 110 that can rotate around an axis. The screen 110 has a function of sieving the classification target (ore) transferred from the drum into a desired particle size. Since the screen 110 is truncated cone-shaped, large-sized ores contained in the ore slurry transferred from the drum of the drum washer by a recovery blade roll along the incline on the screen 110 and are discharged. Each component will be described below.

[0045] In one embodiment of the present invention, the screen 110 includes a lattice-shaped metal grating 111 that extends from the connecting portion with the drum (introduction side 30) along the axial direction, and two layers of expanded metal 112 are provided at the end of the extending metal grating 111 so as to extend along the axial direction (towards discharge side 40). Note that this metal grating 111 may be of an integrated configuration, or may be of a multiple-part configuration consisting of multiple metal gratings.

[0046] As a result, in one embodiment of the present invention, even if the large-sized ore contained in the ore slurry transferred from the drum by the recovery blade falls directly onto the screen 110, the first impact point is the area of ​​the metal grating 111, which has high impact resistance, so that wear and damage due to direct fall are suppressed. Then, even if the large-sized ore impacts the metal grating 111 and then rolls further along the slope to the two layers of expanded metal 112, the impact is weaker than the initial impact, so that wear and damage of the two layers of expanded metal 112 are suppressed compared to conventional screens. In this way, the good screening performance of the lattice-shaped metal grating 111 and the two layers of expanded metal 112 can be maintained. Therefore, the operation of the HPAL plant can be stably performed for a long period of time without stopping for repair or replacement of the screen 110.

[0047] The metal grating 111 preferably extends to a range of 0.25 to 0.5 times the length of the screen 110 in the axial direction, and more preferably 0.3 to 0.4 times. By setting the length in such a range, the energy required to drive the trommel 100 is suppressed, and the large-sized ore transferred from the drum falls on the area where the metal grating 111 is provided, so that the trommel 100 can withstand impacts due to collisions. Therefore, the trommel 100 can maintain its function of screening the ore without being damaged in a short period of time during operation of the HPAL plant, and the life of the trommel 100 itself can be more reliably extended.

[0048] If the metal grating 111 extends less than 0.3 times, the large-sized ore transferred from the drum may jump over the metal grating 111 and fall onto the two layers of expanded metal 112, which may damage the trommel 100 in a short time. In particular, if the metal grating 111 extends less than 0.25 times, the large-sized ore may not only be scooped up or splashed away, but may also pile up and then collapse, causing the large-sized ore to fall directly onto the two layers of expanded metal 112. On the other hand, if the metal grating 111 extends more than 0.4 times, the range of the metal grating 111 in the screen 110 becomes large, and it takes a lot of energy to rotate it. In particular, when the metal grating 111 extends beyond 0.5 times, if the trommel 100 has a shape (trumpet shape) that widens as it moves away from the drum side, the metal grating 111 (heavier than resin) is placed at a position larger than the average radius of the trommel 100. As a result, the moment of inertia is proportional to the square of the radius and further to the density, so a particularly large amount of energy is required to rotate the trommel 100.

[0049] Metallic grating 111 is not particularly limited as long as it is made of a metal, an alloy, or the like, but is preferably made of carbon steel or stainless steel, which have excellent water resistance and impact resistance.

[0050] The thickness of the metal grating 111 is preferably at least 5 mm. By making the thickness 5 mm or more, the metal grating 111 becomes strong, the life span can be extended, and the progress of wear can be easily checked visually. If the thickness is less than 5 mm, there is a risk that the openings of the grating will be wider than the desired range when large-sized ores contained in the ore slurry fall and collide with it.

[0051] Furthermore, as the lattice-shaped metal grating 111, a grating with round holes is used, but this is not limited to this, and metal grating 111 with hexagonal holes, triangular holes, or square holes instead of round holes can also be used without any problems.

[0052] In one embodiment of the present invention, reinforcing frames 120a, 120b may be attached to reinforce the screen 110. Specifically, the reinforcing frame 120a is attached so as to connect the metal grating 111 and the two layers of expanded metal. In addition, a reinforcing frame 120b is attached to the outer peripheral surface of the screen 110 along the longitudinal direction. Furthermore, a reinforcing ring 121a is attached to the inlet side 30 (end on the drum side) of the screen 110, and a reinforcing ring 121b is attached to the discharge side 40 (end opposite the drum) of the screen 110.

[0053] Furthermore, the metal grating 111 is configured in advance to be divided into multiple grating parts, so that if the metal grating 111 becomes damaged or worn during operation of the HPAL plant, it is sufficient to replace only the part corresponding to the damaged area, rather than replacing the entire metal grating 111. This eliminates the need to replace the entire surface, as with conventional wire mesh screens, minimizing costs and labor.

[0054] The expanded metal does not need to be of a special shape, and any commonly available material can be used. The material of the expanded metal is not particularly limited, and may be metal or alloy. For example, stainless steel such as SUS304 is used.

[0055] The two-layered expanded metal 112 is preferably two sheets of the same type of expanded metal stacked together. By stacking two sheets of the same type of expanded metal, even if the inner expanded metal becomes perforated, the outer expanded metal will function to prevent large chunks from being mixed into the subsequent process. In addition, the two layers of expanded metal are preferably stacked so that the positions of the holes in each layer are in the same position. In this way, clogging of the screen with the object to be classified (nickel oxide ore) can be prevented, and a decrease in the screen efficiency can be hardly caused.

[0056] In addition, it is preferable that the metallic grating 111 and the two layers of the expanded metal 112 are connected to be flush with each other inside the screen 110. In this way, the classification target (ore) can be smoothly sent from the metallic grating 111 to the two layers of the expanded metal 112. The thickness of the two layers of the expanded metal 112 is preferably set to a thickness that eliminates a step at the boundary with the metallic grating 111, and if there is a step, it is preferable that the step is smaller than the diameter of the ore particles. In particular, it is appropriate to set the thickness to a step of 25 mm or less, and if the step exceeds 25 mm, it is preferable to renew (re-cover) the two layers of the expanded metal 112 or change the mounting position of the two layers of the expanded metal 112 or the metallic grating 111 so that the step is 25 mm or less. In one embodiment of the present invention, the expanded metal is used in two layers, but in some cases, it may be mounted in a multi-layer of three or more layers.

[0057] In order to reduce the impact that occurs when the ore transfers from the metal grating 111 to the two layers of expanded metal 112, it is desirable to attach the metal grating 111 and the two layers of expanded metal 112 at equal angles.

[0058] In one embodiment of the present invention, a reinforcing material may be provided on the screen 110. For example, a punched metal may be provided along the outer peripheral surface of the screen 110. In this case, the openings of the punched metal are preferably larger than the openings of the metallic grating 111 and the two layers of expanded metal 112 in order to ensure the function of the screen 110 to sieve the ore.

[0059] Fig. 4 is a schematic diagram of a trommel according to another embodiment of the present invention. As shown in Fig. 4, a trommel 200 according to another embodiment of the present invention is provided with a cylindrical screen 210 that can rotate around an axis, and reinforcing frames 220a, 220b and reinforcing rings 221a, 221b are attached to reinforce the screen 210. Each component will be described below. Note that descriptions of components that overlap with the above-mentioned embodiment will be omitted.

[0060] In another embodiment of the present invention, the screen 210 is provided with a lattice-shaped metal grating 211 extending along the axial direction from the connection with the drum, and at the end of the extended metal grating 211, two layers of lattice-shaped expanded metal 212 are provided extending along the axial direction.

[0061] When this trommel 200 is used in a drum washer, the cylindrical screen 210 is connected sideways to the outlet side of the drum and is inclined together with the drum at a predetermined angle (for example, 1° to 20°) with respect to the horizontal direction. At this time, large-sized ores contained in the ore slurry transported by being scooped up by a recovery blade from the drum of the drum washer roll along the incline on the screen 210 and are discharged.

[0062] [3. Effects of the present invention] By employing the trommels 100 and 200 according to an embodiment of the present invention, the following effects can be obtained.

[0063] The first advantage of the present invention is that no emergency repair is required during operation. In other words, even if the inner expanded metal 112a develops a hole, the outer expanded metal 112b is present, so no large chunks are mixed into the subsequent process (see FIG. 3(B)). The inner expanded metal 112a that has developed a hole can be repaired by scheduled maintenance in conjunction with regular maintenance of other equipment, so that no emergency repair is required and the actual equipment operating rate can be maintained at 100%.

[0064] The second effect is the extension of the life of the expanded metal itself. Figures 5(A) to 5(C) are schematic diagrams for explaining the state of wear and damage when only one layer of expanded metal is used, and Figures 5(D) and 5(E) are schematic diagrams for explaining the effect when two layers of expanded metal are used in one embodiment of the present invention. Holes in the expanded metal 12 occur through three processes: (1) a decrease in wire diameter due to wear (Figure 5(A)), (2) the expanded metal 13 whose wire diameter has decreased due to the impact of the falling of a large block undergoes plastic deformation (Figure 5(B)), and (3) the expanded metal 13 falls off due to further impact of the large block (Figure 5(C)). In the present invention, even if the inner expanded metal 112a wears and decreases in wire diameter, the outer expanded metal 112b remains sound, and plastic deformation due to the impact of the falling of a large block can be prevented (Figures 5(D) and 5(E)). Therefore, holes are less likely to form in the inner expanded metal 112a, and as a result, the time it takes for holes to form in the inner expanded metal 112a increases compared to the case of a single layer of expanded metal.

[0065] The third effect is the simple extension of replacement life by making the expanded metal into two layers.

[0066] However, the same effect cannot be obtained by increasing the wire diameter of the expanded metal. The first effect of the present invention is realized by forming the expanded metal into two layers, and in the case of an expanded metal with an increased wire diameter, if a hole is formed, an emergency repair must be performed immediately. In addition, even if the wire diameter is increased, the second effect cannot prevent plastic deformation if the wire diameter decreases due to wear. As a result, the third effect is also considered to be smaller than that of the present invention. In addition, since the expanded metal is a standard product, an expanded metal with an increased wire diameter is a custom-made product, and the screen efficiency is reduced due to the reduced mesh size.

[0067] As described above, the trommel according to one embodiment of the present invention is provided with a cylindrical screen that is connected to a drum of a drum washer and can rotate around an axis. The screen is characterized in that it has a metal grating on the inlet side, and two layers of expanded metal are provided at the tip of the discharge side of the metal grating so as to extend further from the discharge side.

[0068] As a result, the large-sized ore contained in the ore slurry is picked up by the recovery blades installed in the drum, and the large-sized ore transferred from the drum to the trommel falls into the area where the metal grating is installed, so that the screen installed in the trommel can withstand strong impacts. In addition, by providing two layers of expanded metal to extend further from the discharge side of the metal grating, the trommel screen is not damaged in a short period of time during operation of the HPAL plant, and the life of the trommel itself can be extended. As a result, there is no need to frequently stop operation to repair or replace the trommel screen. Furthermore, the drum washer, which has a drum connected to the trommel, is ideal for screening nickel raw ore in a hydrometallurgical plant, as it allows the HPAL plant to be operated efficiently with less frequent stoppages. EXAMPLES

[0069] EXAMPLES The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to these examples or comparative examples.

[0070] In a HPAL (High Pressure Acid Leaching) plant, nickel oxide ore was slurried as a pretreatment for acid leaching of the nickel oxide ore using a drum washer connected to a trommel under the conditions of Example 1 and Comparative Example 1 below.

[0071] Example 1 In Example 1, the first row screen on the introduction side (the end on the drum side, which also serves as the connection part with the drum in this embodiment) of the conical trommel screen, where the ore discharged from the drum unit of the drum washer falls first, is provided with a metal grating (width 800 mm x width 1250 mm x thickness 25 mm) made of flat steel (horizontal length 24 mm x thickness 5.0 mm) arranged in a grid pattern, in consideration of impact resistance. The second row screen and the third row screen are provided with two layers of expanded metal. Furthermore, a reinforcing frame and a reinforcing ring are attached to each screen. The first row screen to the third row screen are arranged at equal intervals (each of which is one-third of the overall length of the screen).

[0072] As a result of operating the HPAL plant, the first row screen (metal grating) required repair and replacement within one year of use, as shown in Table 1. The second and third row screens (two-layer expanded metal) did not require repair for more than six months after use began, and the replacement period was one year after use began.

[0073] [Table 1]

[0074] Comparative Example 1 In Comparative Example 1, the first row screen on the inlet side of the conical trommel screen, where the ore discharged from the drum unit of the drum washer first falls, is a metal grating (width 800 mm × horizontal length 1250 mm × thickness 25 mm) arranged in a grid pattern, and the second and third row screens are urethane screens with a thickness of 30 mm (mesh opening 25 mm), and a perforated iron plate with a thickness of 6 mm is further attached along the outer periphery of this urethane screen for reinforcement, forming a double-structure screen. Furthermore, a reinforcing frame and a reinforcing ring are attached to each screen. The first row screen to the third row screen are arranged at equal intervals (each of which is one-third the length of the entire screen). The urethane screen refers to a screen formed of polyurethane.

[0075] As a result of operating the HPAL plant, the first screen required repair and replacement one year after the start of use, as shown in Table 2. The second and third screens required repair and replacement four to six months after the start of use, and six to eight months after the start of use, respectively.

[0076] [Table 2]

[0077] Comparing Table 1 (Example 1) with Table 2 (Comparative Example 1), it can be seen that the period until the screen needs repair or replacement is longer in Example 1 than in Comparative Example 1, that is, the trommel can be used for a long period of time. As a result, the operating rate of the present equipment based on Example 1 is improved, and stable operation is possible. Furthermore, even in the operation after the implementation, only ores with a size of 25 mm or less were observed on the sieve, and it was confirmed that the ore slurry containing ores with a particle size narrower than the opening of the screen could be collected.

[0078] In this way, it was confirmed that by providing a metal grating that extended along the axis from the connecting part with the drum (the base end of the screen) used in Example 1 and providing two layers of expanded metal that extended further from the tip of the metal grating on the discharge side, the time to require repair or replacement was extended longer than in the trommel used in Comparative Example 1, which had a urethane screen and punched metal that extended further from the tip of the metal grating on the discharge side. In other words, it is believed that the trommel used in Example 1 was able to extend its lifespan during the operation of the HPAL plant.

[0079] Although one embodiment and examples of the present invention have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present invention. Therefore, all such modifications are intended to be included within the scope of the present invention.

[0080] For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning can be replaced with the different term anywhere in the specification or drawings. In addition, the configurations of the slurry transport equipment and the slurry delivery method are not limited to those described in the embodiment and examples of the present invention, and various modifications are possible. [Explanation of symbols]

[0081] 1 drum washer, 10 drum, 11 recovery blade, 12 expanded metal, 13 expanded metal with reduced wire diameter, 20 trommel, 30 inlet side, 40 outlet side, 100 trommel, 110 screen, 111 metal grating, 112 two layers of expanded metal, 112a inner expanded metal, 112b outer expanded metal, 120a, 120b reinforcing frame, 121a, 121b reinforcing ring, 200 trommel, 210 screen, 211 metal grating, 212 expanded metal, 220a, 220b reinforcing frame, 221a, 221b reinforcing ring, S ore slurry

Claims

1. A trommel having a truncated cone-shaped or cylindrical screen that is connected to a drum of a drum washer and can rotate around an axis, the screen has an inlet side into which the object to be classified is introduced and a discharge side from which the object to be classified remaining after classification is discharged, The screen includes a metal grating on the inlet side, A trommel characterized in that two layers of expanded metal are provided at the tip of the discharge side of the metallic grating so as to extend further from the discharge side.

2. 2. The trommel according to claim 1, wherein the two layers of expanded metal are two sheets of the same type of expanded metal stacked together.

3. 3. The trommel according to claim 1, wherein the two layers of expanded metal are stacked so that the holes of the two layers are in the same position.

4. 4. The trommel according to claim 1, wherein the metal grating and the two layers of expanded metal are connected to be flush with each other on the inside of the screen.

5. 5. The trommel according to claim 1, wherein the metal grating extends in the range of 0.3 to 0.4 times the length of the screen in the axial direction.

6. 6. The trommel according to claim 1, wherein the metal grating has a thickness of 5 mm or more.

7. 7. The trommel according to claim 1, wherein the metal grating is divided into a plurality of sections.

8. The drum washer is used to screen nickel raw ore in hydrometallurgical plants.

8. The trommel according to claim 1, further comprising:

Images