JP7639639B2 - Trommel - Google Patents

Description

The present invention relates to a trommel, and more specifically to a trommel attached to a drum washer that screens nickel raw ore used in HPAL plants.

In recent years, high pressure acid leach 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%.

In HPAL plants that use low-grade nickel ore, the raw material nickel ore is transported and supplied from the mine. This ore contains large-sized ore, which becomes an obstacle when transporting it using pumps, etc. Furthermore, 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, which prepares the nickel ore for the HPAL plant, washing and screening equipment is installed to remove the large-sized ore.

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 conical or cylindrical screen that is set horizontally (with the axis horizontal or inclined to a position close to horizontal), and by rotating the screen around the axis, it 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. One application of such a trommel is the classification process of nickel oxide ore.

For example, in Patent Document 1, in order to prevent a significant decrease in efficiency when crushing and classifying nickel ore to prepare the raw material, a protrusion that meets certain requirements is proposed on the same circumference of the inner surface of the trommel in a vertical cross section relative to the trommel rotation axis.

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 impact of the large-sized ores falling during rotation causes the trommel screen to wear or break, requiring repairs during operation. Repairs during operation can affect the operating rate of downstream equipment and may also reduce production efficiency.

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

In one embodiment of this type of trommel, the trommel is divided lengthwise into three sections, 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.

JP 2009-173967 A JP 2018-183726 A

However, because the scheduled maintenance cycle for HPAL plants is every six months, even if the technology in Patent Document 2 were to extend the screen's lifespan to four to six months, emergency repairs would still be necessary while the HPAL plant was in operation, which would result in reduced production. In addition, resin screens such as urethane screens are relatively expensive and take a long time to obtain.

The present invention has been proposed in light of these circumstances, and aims 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 nickel raw ore.

That is, in order to achieve the above object, in one aspect of the present invention, a trommel is provided with 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 introduction side where the objects to be classified are introduced and a discharge side where the objects to be classified that remain after classification are discharged, the screen has 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.

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

In this case, in one aspect of the present invention, the two-layer expanded metal may be 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 develops a hole, the outer expanded metal will continue to function, eliminating the need for emergency repairs.

In one aspect of the present invention, two layers of expanded metal may be stacked so that the holes in each layer are in the same position.

This way, there is almost no loss in screen efficiency.

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

By doing this, the material to be classified (ore) can be smoothly sent from the metal grating to the two layers of expanded metal.

In one aspect of the present invention, the metal grating may extend to a range of 0.3 to 0.4 times the length of the screen in the axial direction.

This allows large ore particles transported from the drum to fall onto the metal grating.

In one aspect of the present invention, the thickness of the metal grating may be 5 mm or more.

By keeping the thickness of the metal grating within the above range, the metal grating becomes sturdy, extending its lifespan, and it also becomes easier to visually check the progress of wear.

In one aspect of the present invention, the metal grating may be configured to be divided into multiple parts.

In this way, repairs do not require replacing the entire metal grating, but only the portion that corresponds to the damaged area.

In one aspect of the present invention, the drum washer may be used to screen nickel raw ore in a hydrometallurgical plant.

The trommel according to one aspect of the present invention is preferably used as a drum washer for screening nickel raw ore used in HPAL plants.

According to the present invention, it is possible to further extend the life of the screen with a simple configuration while maintaining the screening performance of nickel raw ore.

FIG. 1 is a process diagram of a hydrometallurgical method for nickel oxide ore by high pressure acid leaching. FIG. 2 is a schematic diagram of a drum washer. 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. FIG. 4 is a schematic diagram of a trommel according to another embodiment of the present invention. 5(A) to (C) are schematic diagrams illustrating the wear and breakage conditions when only one layer of expanded metal is used, and FIGS. 5(D) and (E) are schematic diagrams illustrating the effect of using two layers of expanded metal in one embodiment of the present invention.

The following describes in detail a preferred embodiment of the present invention. Note that the embodiment described below does not unduly limit the content of the present invention described in the claims, and not all of the configurations described in the embodiment are necessarily essential as a means of solving the problem of the present invention.

[1. Overview]
The trommel according to one embodiment of the present invention is used in conjunction with a drum washer for sieving nickel raw ore in a method for hydrometallurgy of nickel oxide ore. The hydrometallurgy of nickel oxide ore is a smelting process for leaching and recovering nickel from nickel oxide ore, for example, by using a high-pressure acid leaching method (HPAL method). The trommel according to one embodiment of the present invention is not necessarily limited to classification in the hydrometallurgy 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.

Figure 1 is a process diagram of a hydrometallurgical method using high-pressure acid leaching of nickel oxide ore. As shown in Figure 1, the hydrometallurgical process of nickel oxide ore includes an ore slurrying process S1 in which nickel oxide ore is slurried, an ore slurry concentrating process S2 in which water contained in the ore slurry is removed to concentrate the ore components, a leaching process S3 in which sulfuric acid is added to the produced ore slurry and leaching is performed under high temperature and high pressure, a solid-liquid separation process S4 in which the resulting leaching slurry is washed in multiple stages to separate the residue (leaching residue) and obtain a leachate containing nickel and impurity elements, a neutralization process S5 in which limestone is added to the leachate as a neutralizing agent to adjust the pH of the leachate, a neutralization precipitate containing impurity elements is separated, and a neutralization final solution containing nickel is obtained, and a sulfurization process S6 in which a sulfurizing agent is added to the neutralization final solution to generate a sulfide containing nickel (nickel sulfide).

Furthermore, this hydrometallurgical method includes a final neutralization process S7 in which the leaching residue separated in the solid-liquid separation process S4 and the poor liquid discharged in the sulfidation process S6 are collected and rendered harmless. This final neutralization process S7 is a step-by-step neutralization process consisting of a first stage neutralization process (first final neutralization process) using limestone as a neutralizing agent, and a second stage neutralization process (second final neutralization process) 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).

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

Figure 2 is a schematic diagram of a drum washer. As shown in Figure 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 the function of crushing and repulping nickel oxide ore to produce an ore slurry S. The recovery blade 11 has the function of scraping up the ore contained in the ore slurry S from within the drum 10. The trommel 20 has the function of sieving the ore contained in the ore slurry S.

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 ore is slurried with water from the large particle size ore inside the drum 10 and sent to the trommel 20, a large classification device, where the screen of this trommel 20 removes ore with a particle size of 25 mm or more contained in the ore slurry S. Furthermore, a sifter located 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.

Therefore, a large classification device called a trommel 20 is installed on the outlet side (downstream side) of the drum 10 to sift out the ore slurry S and the large-grained ore. The screen of this trommel 20 is in a truncated cone or cylindrical shape, and the trommel 20 is connected to the drum 10 so that it can sift the input materials while rotating together with the drum 10.

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 the 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 scooped up from within the drum 10 system, and the ore contained in the ore slurry is transferred smoothly from the drum 10 to the trommel 20. As a result, an ore slurry with a stable ore content is obtained, and since large-sized ore is less likely to remain in the drum 10, wear on the drum 10 itself can be suppressed and the energy required to drive the drum 10 is also reduced.

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.

If the screen of the trommel 20 breaks, large-sized ore will be carried to the downstream sieving machine, increasing the load on the sieving machine and making it more susceptible to damage. If the sieving machine breaks, the large-sized ore will subsequently clog the narrow parts of the pumps and valves, blocking the flow path of the ore slurry, and the equipment will have to be shut down 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 wear or damage to the screen of the trommel 20 is confirmed, 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 equipment's operating rate.

To prevent wear and tear on the screens, for example, thick metal gratings can be provided on all screens. However, the trade-off for ensuring the strength of the screens is that the opening area for sieving is insufficient, causing excessive discharge of the raw ore slurry outside the trommel 20 system, and the weight of the equipment increases, making operation difficult. On the other hand, if all 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, and the openings in the plastic screens gradually widen during operation, making it impossible to filter out ores larger than the desired particle size.

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

[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 its axis. The screen 110 has an inlet side 30 where the objects to be classified are introduced and an outlet side 40 where the objects to be classified remaining after classification are discharged. The screen 110 has a metal grating 111 on the inlet side 30, and two layers of expanded metal 112 are provided at the tip of the outlet side 40 of the metal grating 111 so as to extend further from the outlet side 40.

As shown in FIG. 3(A), the trommel 100 according to one embodiment of the present invention is provided with a truncated cone-shaped screen 110 that can rotate around an axis. The screen 110 has the function of sifting the object to be classified (ore) transferred from the drum into the desired particle size. Since the screen 110 is truncated cone-shaped, large-sized ore contained in the ore slurry transferred from the drum of the drum washer by the recovery blades rolls along the incline on the screen 110 and is discharged. Each component will be described below.

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

In this way, 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 highly impact-resistant metal grating 111, so wear and damage due to direct fall is suppressed. And even if this 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 wear and damage to the two layers of expanded metal 112 is 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.

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 to a range of 0.3 to 0.4 times. By setting it to such a range, the energy required to drive the trommel 100 is suppressed, and the area where the metal grating 111 is provided is where the large-sized ore transferred from the drum falls, so that it can withstand the impact of a collision. 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.

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 period of 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 fall directly onto the two layers of expanded metal 112 due to the large-sized ore collapsing after piling up on top of each other. 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, if the metal grating 111 extends beyond 0.5 times, and 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) will be 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 is also proportional to the density, so a particularly large amount of energy is required to rotate the trommel 100.

The metal grating 111 is not particularly limited as long as it is made of a metal or alloy, but it is preferable that it is made of carbon steel or stainless steel, which have excellent water resistance and impact resistance.

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 stronger, 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 large-sized ores contained in the ore slurry will fall and collide with the grating, causing the openings in the grating to widen beyond the desired range.

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

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 to connect the metal grating 111 and the two layers of expanded metal. 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 (the end on the drum side) of the screen 110, and a reinforcing ring 121b is attached to the outlet side 40 (the end opposite the drum) of the screen 110.

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 at 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 effort.

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 can be metal or alloy. For example, stainless steel such as SUS304 can be used.

The two-layer expanded metal 112 is preferably made by stacking two sheets of the same type of expanded metal. 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 subsequent processes. It is also preferable to stack the two layers of expanded metal so that the positions of the holes in each layer are in the same position. This can prevent clogging of the screen with the material to be classified (nickel oxide ore), and can cause almost no decrease in screen efficiency.

It is also preferable that the metallic grating 111 and the two layers of expanded metal 112 are connected to be flush with each other on the inside of the screen 110. In this way, the classification target (ore) can be smoothly sent from the metallic grating 111 to the two layers of expanded metal 112. The thickness of the two layers of 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. For example, if the step exceeds 25 mm, it is preferable to renew (reupholster) the two layers of expanded metal 112 or change the mounting position of the two layers of 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 installed in multiple layers of three or more.

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 install the metal grating 111 and the two layers of expanded metal 112 at equal angles.

In one embodiment of the present invention, the screen 110 may be provided with a reinforcing material. For example, a punched metal may be provided along the outer peripheral surface of the screen 110. In this case, it is preferable that the mesh size of the punched metal is larger than the mesh size of the metal grating 111 and the two layers of expanded metal 112 in order to ensure the screen 110's function of screening out the ore.

Figure 4 is a schematic diagram of a trommel according to another embodiment of the present invention. As shown in Figure 4, the 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.

In another embodiment of the present invention, the screen 210 is provided with a lattice-shaped metal grating 211 that extends from the connection with the drum along the axial direction, and at the tip of the metal grating 211, a lattice-shaped two-layer expanded metal 212 is provided that extends along the axial direction.

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 (e.g., 1° to 20°) from the horizontal. At this time, large-sized ores contained in the ore slurry transported by being scooped up by the recovery blades from the drum of the drum washer roll along the incline on the screen 210 and are discharged.

[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.

The first advantage of the present invention is that no emergency repairs are 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 downstream process (see Figure 3 (B)). The inner expanded metal 112a that has developed a hole can be repaired as scheduled in conjunction with regular maintenance of other equipment, so that no emergency repairs are required at all, and the actual equipment operating rate can be maintained at 100%.

The second effect is the extension of the life of the expanded metal itself. Figures 5(A) to (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 (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 the wire diameter decreases, the outer expanded metal 112b is sound, and plastic deformation due to the impact of the falling of the large block can be prevented (Figures 5(D) and (E)). This makes it less likely for holes 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 when there is only one layer of expanded metal.

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

The same effect cannot be obtained by increasing the wire diameter of the expanded metal. The first effect of the present invention is achieved by using two layers of expanded metal, and if a hole develops in expanded metal with an increased wire diameter, emergency repairs must be made immediately. As for the second effect, no matter how much the wire diameter is increased, it is not possible to prevent plastic deformation if the wire diameter decreases due to wear. As a result, the third effect is also thought to be smaller than that of the present invention. In addition, since expanded metal is a standard product, products with an increased wire diameter are custom-made, and the reduced mesh size leads to a decrease in screen efficiency.

As described above, the trommel according to one embodiment of the present invention is connected to a drum of a drum washer and is provided with a cylindrical screen that can rotate around an axis. The screen is characterized by having 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.

As a result, the large-sized ore contained in the ore slurry is scooped 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 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, a drum washer equipped with a drum connected to a 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.

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.

In a HPAL (high pressure acid leaching) plant, nickel oxide ore was slurried as a pretreatment for acid leaching using a drum washer connected to a trommel under the conditions of Example 1 and Comparative Example 1 below.

Example 1
In Example 1, the first row screen on the inlet 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 (width 24 mm x thickness 5.0 mm) arranged in a grid pattern, taking impact resistance into consideration. 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).

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

(Comparative Example 1)
In Comparative Example 1, the first 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 x horizontal length 1250 mm x thickness 25 mm) arranged in a grid pattern, and the second and third screens are urethane screens with a thickness of 30 mm (mesh size 25 mm), and a perforated iron plate with a thickness of 6 mm is further attached along the outer periphery of the urethane screen for reinforcement, forming a double-structure screen. Furthermore, a reinforcing frame and a reinforcing ring are attached to each screen. The first to third screens are arranged at equal intervals (each of which is one-third the length of the entire screen). The urethane screen refers to a screen made of polyurethane.

As a result of operating the HPAL plant, as shown in Table 2, the first row screen required repair and replacement one year after the start of use. The second and third row 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.

Comparing Table 1 (Example 1) with Table 2 (Comparative Example 1), it can be seen that in Example 1, the time until the screen needed repair or replacement was longer than in Comparative Example 1, meaning that the trommel could be used for a longer period of time. As a result, the operating rate of the present equipment based on Example 1 was improved, enabling stable operation. Furthermore, even during operation after the implementation, only ores with sizes of 25 mm or less were observed on the sieve, confirming that it was possible to recover an ore slurry containing ores with particle sizes narrower than the screen openings.

In this way, it was confirmed that by providing a metal grating that extends from the connection part with the drum (base end of the screen) used in Example 1 along the axis and providing two layers of expanded metal that extend further from the tip of the discharge side of the metal grating, 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 discharge side of the metal grating. 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.

Although one embodiment and example 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 that do not substantially deviate 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.

For example, a term that is described at least once in the specification or drawings together with a different term having a broader or synonymous meaning may be replaced with that 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.

1 Drum washer, 10 Drum, 11 Recovery blade, 12 Expanded metal, 13 Expanded metal with reduced wire diameter, 20 Trommel, 30 Inlet side, 40 Discharge side, 100 Trommel, 110 Screen, 111 Metal grating, 112 Two layers of expanded metal, 112a Inner expanded metal, 112b Outer expanded metal, 120a, 120b Reinforcement frame, 121a, 121b Reinforcement ring, 200 Trommel, 210 Screen, 211 Metal grating, 212 Expanded metal, 220a, 220b Reinforcement frame, 221a, 221b Reinforcement ring, S Ore slurry

Claims (8)

A trommel is provided with 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. The trommel according to claim 1, characterized in that the two layers of expanded metal are two sheets of the same type of expanded metal stacked together. The trommel according to claim 1 or 2, characterized in that the two layers of expanded metal are stacked so that the holes are in the same position. A trommel according to any one of claims 1 to 3, characterized in that the metal grating and the two layers of expanded metal are connected flush with each other on the inside of the screen. A trommel according to any one of claims 1 to 4, characterized in that the metal grating extends to a range of 0.3 to 0.4 times the length of the screen in the axial direction. A trommel according to any one of claims 1 to 5, characterized in that the thickness of the metal grating is 5 mm or more. The trommel according to any one of claims 1 to 6, characterized in that the metal grating is divided into multiple parts. 8. The trommel according to claim 1, wherein the drum washer is used for screening nickel raw ores in a hydrometallurgical plant.

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