Chromite ore separation and recovery equipment, and chromite ore recovery method

Abstract

To stably and uniformly distribute a slurry from an upstream device to a plurality of devices arranged side by side on a downstream side in a chromite ore capture facility including a configuration where separation device of the same kind are arranged side by side.SOLUTION: A chromite ore capture facility includes a classification processing device 1 and a plurality of gravity separation devices 3. The chromite ore capture facility 10 includes a slurry relay tank 2 having a plurality of overflow weirs 22 that uniformly distribute and discharge a stirred slurry toward a downstream side, and a dilution water supply device 4 configured by connecting a dilution water supply pipe 41 to a slurry flow pipe 15 connecting the classification processing device 1 and the slurry relay tank 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a separation and recovery facility for chromite ore and a method for recovering chromite ore. More specifically, the present invention relates to a separation and recovery facility for chromite ore that separates and recovers chromite ore containing iron from an ore slurry to be subjected to leaching treatment in a wet smelting method for recovering nickel and cobalt from nickel oxide ore by a high-pressure acid leaching method, and a method for recovering chromite ore.

Background Art

[0002] In recent years, in mineral resources such as coal, iron, copper, nickel, cobalt, chromium, and manganese, the oligopolization of mining rights has been progressing, and raw material costs have been rising significantly. Therefore, as a measure for cost reduction in the metal smelting field, technical development has been carried out to use low-grade raw materials that have not been used as targets because of their cost disadvantage.

[0003] Also at nickel smelting sites, separation and recovery of chromite ore from an ore slurry, which is a mixture of nickel oxide ore and water, is carried out in a plant of a wet smelting method based on the high-pressure acid leaching (High Pressure Acid Leach) method in which nickel oxide ore is acid-leached under pressure with sulfuric acid. Such separation and recovery of chromite ore is performed in a separation and recovery facility in which a classification treatment device that separates the slurry according to the particle size difference of the particles contained in the ore slurry and a specific gravity separation device that separates and recovers a high-chromium concentration slurry in which the chromium content is further concentrated by a specific gravity separation treatment from the slurry classified on the coarse particle side are connected (see Patent Documents 1 and 2).

[0004] In a separation and recovery facility consisting of multiple types of separation devices connected together as described above, the most common method for increasing the processing capacity of ore slurry is to add identical devices in parallel to each processing stage, rather than increasing the size of individual devices. This is because adding existing devices in parallel, where processing conditions have already been stably established, makes it easier to predict changes in slurry concentration and particle size distribution due to changes in the equipment configuration, and thus makes it relatively easy to appropriately manage the operating conditions of the entire facility, rather than replacing existing devices with new, larger devices.

[0005] For example, in the above-mentioned separation and recovery facility, which consists of multiple types of separation devices connected together, if multiple specific gravity separation devices are installed in parallel downstream, it is necessary to stably supply the desired amount of slurry from the upstream classification device to each of the multiple specific gravity separation devices downstream. To achieve this, it is conceivable to distribute the slurry to the downstream devices using a liquid supply piping equipped with branched pipes. However, with this method, the slurry flow rate tends to fluctuate locally due to uneven flow of solids within the liquid supply piping, making it difficult to stably and evenly distribute the slurry. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-107289 [Patent Document 2] Japanese Patent Publication No. 2017-52992 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to stably and evenly distribute slurry to multiple devices arranged in parallel downstream from an upstream device in a chromite ore separation and recovery facility comprising a configuration in which identical separation devices are installed in parallel. [Means for solving the problem]

[0008] The inventors of the present invention have found that the above problems can be solved by installing a slurry relay tank having multiple overflow weirs as slurry discharge ports upstream of the multiple parallel-arranged separation devices in a chromite ore separation and recovery facility comprising a configuration in which the same type of separation device is installed in parallel, and by further installing a dilution water supply device that injects an appropriate amount of dilution water to adjust the slurry concentration into the piping that transports the slurry to the slurry relay tank, and have completed the present invention. Specifically, the present invention provides the following.

[0009] (1) A chromite ore separation and recovery facility comprising: a classification device for separating and recovering a chromium-containing slurry from an ore slurry based on the particle size difference of the particles constituting the ore slurry; and a plurality of specific gravity separation devices located downstream of the classification device for separating and recovering a high-chromium-concentration slurry from the slurry separated and recovered by the classification device through a specific gravity separation treatment, wherein the facility further comprises a slurry relay tank and a dilution water supply device, the slurry relay tank being installed between the classification device and the specific gravity separation device, and having an agitator and a plurality of overflow weirs for evenly distributing and discharging the agitated slurry downstream, and a dilution water supply pipe extending from the dilution water supply device being connected to a slurry flow pipe connecting the classification device and the slurry relay tank.

[0010] According to the chromite ore separation and recovery equipment of (1), slurry can be stably and evenly distributed from the upstream classification device to multiple specific gravity separation devices arranged in parallel downstream. Furthermore, by configuring the system to directly inject dilution water into the slurry flow pipe, blockage of the slurry flow pipe due to slurry stagnation can be prevented.

[0011] (2) The chromite ore separation and recovery facility according to (1), wherein the overflow weir is equipped with an overflow weir closing mechanism that can stop the discharge of slurry as needed, and the number of overflow weirs is greater than the number of specific gravity separation devices connected to the downstream side of the slurry relay tank.

[0012] According to the chromite ore separation and recovery equipment of (2), the overflow weirs exceeding the number of downstream specific gravity separation devices currently in operation can be closed, and in the future, when additional specific gravity separation devices are installed, these can be opened and made functional. This provides the chromite ore separation and recovery equipment with the flexibility to adapt to changes in the number of specific gravity separation devices.

[0013] (3) The chromite ore separation and recovery apparatus according to (1) or (2), wherein the flow path of the liquid phase overflowing the overflow weir is a flow path with a substantially rectangular vertical cross-sectional shape and a flat bottom.

[0014] In the chromite ore separation and recovery equipment of (3), the relationship between the flow rate of the liquid phase overflowing the overflow weir and the head (height of the overflow liquid surface) h maintains a linear correlation. Compared to triangular overflow weirs with uneven bottoms, the fluctuation in slurry discharge when the liquid surface height of the slurry in the tank fluctuates locally can be suppressed to a smaller fluctuation range, thereby further improving the stability of the uniform distribution of slurry to the downstream equipment in the chromite ore separation and recovery equipment of (1) or (2).

[0015] (4) A chromite ore separation and recovery apparatus according to any one of (1) to (3), wherein the classification apparatus is a hydrocyclone and the specific gravity separation apparatus is a density separator and / or spiral concentrator.

[0016] According to the chromite ore separation and recovery equipment of (4), in the process of separating and recovering chromite ore from nickel oxide ore slurry through multiple steps, the amount of slurry supplied to the downstream specific gravity separation step can be stably maintained within an appropriate range, thereby stably improving the chromium separation and recovery rate.

[0017] (5) A method for recovering chromite ore by separating and recovering chromite ore from nickel oxide ore slurry, comprising: a classification step of separating the slurry according to the particle size difference of the contained particles; a slurry concentration adjustment step of adjusting the slurry concentration by injecting dilution water into the slurry classified to the coarser side in the classification step; a slurry distribution step of distributing the slurry whose slurry concentration has been adjusted in the slurry concentration adjustment step evenly into a plurality of slurry channels by passing it through a slurry relay tank having a stirrer and a plurality of overflow weirs as slurry discharge ports; and a specific gravity separation step of separating and recovering a high chromium concentration slurry from each of the slurries distributed in the slurry distribution step by a specific gravity separation device, wherein in the slurry concentration adjustment step, the amount of dilution water injected is adjusted so that the slurry concentration introduced into the slurry distribution step is 35% or more and 40% or less.

[0018] According to the chromite ore recovery method of (5), slurry can be stably and evenly distributed from the upstream classification device to multiple gravity separation devices arranged in parallel downstream. Furthermore, by maintaining the concentration of the slurry supplied from the upstream classification device to the multiple gravity separation devices arranged in parallel downstream within a predetermined range, crushing by collisions between particles in the slurry relay tank is promoted in the slurry distribution process, thereby improving the separation and recovery rate of chromium in the gravity separation process.

[0019] (6) The method for recovering chromite ore according to (5), wherein the cross-sectional shape of the flow path of the overflow liquid in the overflow weir of the slurry relay tank in which the slurry distribution step is performed is a rectangle with a flat bottom, and the slurry distribution step is performed while maintaining the relationship between the flow path width d of the flow path and the height h of the liquid surface of the overflow liquid in the range of 0.5d ≤ h ≤ 2d.

[0020] According to the method for recovering chromite ore of (6), it is possible to prevent wear of the flow path due to an excessive flow velocity of the discharged slurry, and moreover, the influence of fluctuations in the local liquid level height of the slurry in the tank on the flow velocity of the discharged slurry can be suppressed to a small level, enhancing the stability of the uniform distribution of the slurry.

Effects of the Invention

[0021] According to the present invention, in a chromite ore separation and recovery facility including a configuration in which the same type of separation devices are installed in parallel, it is possible to stably and uniformly distribute slurry to a plurality of devices arranged in parallel from the upstream device to the downstream side.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram schematically showing the overall configuration of the chromite ore separation and recovery facility of the present invention. [Figure 2] It is a schematic diagram showing the basic configuration of a hydrocyclone suitable as a classification treatment device constituting the chromite ore separation and recovery facility of the present invention. [Figure 3] It is a plan view of a slurry relay tank constituting the chromite ore separation and recovery facility of the present invention. [Figure 4] It is a partially enlarged view of the slurry relay tank shown in FIG. 3, and is a diagram showing the configuration around the overflow weir. [Figure 5] It is a process diagram showing the flow of the overall process of a wet smelting process for recovering nickel and cobalt from nickel oxide ore. [Figure 6] It is a process diagram showing the general flow of a method for recovering chromite ore performed as a partial process of the overall process of FIG. 5.

Embodiments for Carrying Out the Invention

[0023] The following describes in detail specific embodiments of the "chromite ore separation and recovery equipment" and the "chromite ore recovery method" of the present invention. It should be noted that the present invention is not limited to the following embodiments, and various modifications are possible without altering the essence of the invention.

[0024] <Chromite ore separation and recovery facility> The "chromite ore separation and recovery equipment" of the present invention is equipment that performs a process of recovering chromite ore from the ore slurry (chromite ore recovery process S2) in parallel with the pretreatment of the ore slurry when carrying out the ore slurry processing process S2 (see Figure 5), which is a partial process of the "wet smelting method for nickel oxide ore" described later.

[0025] [Overall structure] Figure 1 is a schematic diagram showing the overall configuration of a chromite ore separation and recovery facility 10, which is an example of an embodiment of the "chromite ore separation and recovery facility" of the present invention. As shown in the figure, the chromite ore separation and recovery facility 10 is composed of at least a classification processing device 1, a slurry relay tank 2, a plurality of specific gravity separation devices 3 (3A, 3B, 3C, 3D), and a dilution water supply device 4.

[0026] In the chromite ore separation and recovery facility 10, multiple specific gravity separation devices 3 (3A, 3B, 3C, 3D) are arranged in parallel downstream of the classification device 1, with a slurry relay tank 2 in between that distributes the slurry to each of the specific gravity separation devices 3A, 3B, 3C, and 3D. As an example, the number of these specific gravity separation devices 3 is four, as shown in the diagram, but it is not limited to this, and any number of two or more can be installed as needed.

[0027] Furthermore, a slurry conveying pipe 15 is installed between the coarse particle side discharge port (underflow discharge port 14 in Figure 2) of the classification device 1 and the slurry relay tank 2, to convey the slurry that has been classified by the classification device 1 to the slurry relay tank 2, which has been sorted to the slurry with relatively larger particle size (coarse particle).

[0028] A dilution water supply pipe 41 is connected to the dilution water supply device 4, which injects the dilution water supplied from the device into the slurry flow pipe 15. The dilution water supply pipe 41 extends from the dilution water supply device 4 and is connected to the slurry flow pipe 15, which is installed connecting the classification processing device 1 and the slurry relay tank 2, in such a manner that it can inject dilution water into the pipe.

[0029] [Classification Processing Equipment] The classification apparatus 1 is a device that classifies ore slurries such as nickel oxide ore according to the difference in particle size of the particles contained in the ore slurry. Specifically, a hydrocyclone can be preferably used as the classification apparatus. A "hydrocyclone" is a known device that can classify solid particles dispersed in a slurry mainly according to differences in particle size using centrifugal force (see, for example, Japanese Patent Publication No. 55-1047666).

[0030] The hydrocyclone 1 shown in Figure 3 is an example of a hydrocyclone that can be preferably used in the present invention. With the hydrocyclone 1, by supplying nickel oxide ore slurry from the supply pipe 12 at a predetermined pressure, a downward flow that swirls down near the wall surface inside the tapered cylindrical section 11 and an upward flow that rises near the center are generated, thereby separating the nickel oxide ore slurry into coarse and fine particles.

[0031] Here, generally, the specific gravity of chromite is equivalent to that of iron hydroxide such as goethite, but because the particle sizes are different, coarse chromite and fine goethite can be efficiently separated by a "hydrocyclone". From the overflow outlet 13 of hydrocyclone 1, a mixture containing relatively small-grained goethite (fine particles) is discharged as overflow (O / F) and sent to the leaching process S3 as raw material for nickel recovery. Then, from the spigot (underflow outlet) 14 of hydrocyclone 1, a mixture containing relatively large-grained chromite ore (coarse particles) is discharged as underflow (U / F), and this underflow (U / F) is sent to the slurry relay tank 2 through the slurry flow pipe 15.

[0032] [Slurry relay tank] As shown in Figure 3, the slurry relay tank 2 is a cylindrical storage tank equipped with multiple overflow weirs 22 (22A, 22B, 22C, 22D) and an agitator 24. In the slurry relay tank 2, the slurry that has been transported from the classification treatment device 1 through the slurry transport pipe 15 in the chromite ore separation and recovery equipment 10 is temporarily stored, agitated in the tank, and then discharged evenly from each of the overflow weirs 22A, 22B, 22C, 22D. It is preferable that the slurry relay tank 2 has a capacity that allows for a residence time of 1 minute or more.

[0033] It is preferable that the multiple overflow weirs 22 (22A, 22B, 22C, 22D) are provided at equal intervals in the circumferential direction of storage within the tank at the upper end of the side wall of the tank body 23, as shown in Figure 3. In this specification, "overflow weir" refers to a type of outlet structure for controlling the amount of liquid phase discharged in a tank capable of storing a liquid phase, and is an outlet structure that allows overflow liquid within a certain range to flow out evenly over the weir at a predetermined discharge rate by appropriately setting the height of the weir relative to the liquid level of the liquid phase. As an example, the overflow weirs 22 (22A, 22B, 22C, 22D) can be constructed by forming a rectangular cutout at the upper end of the side wall of the tank body 23, as shown in Figure 4.

[0034] Preferably, each overflow weir 22 (22A, 22B, 22C, 22D) is equipped with an overflow weir closing mechanism that can, if necessary, close the outflow path of the overflow liquid formed above the upper edge of the weir. The overflow weir closing mechanism can be provided, for example, by installing a closing plate that can cover the entire opening portion of the rectangular cutout constituting the overflow weir from the inside of the tank, and which can be moved up and down as necessary to open and close the opening portion.

[0035] Furthermore, if the overflow weir 22 is equipped with an overflow weir closing mechanism, the slurry relay tank 2 can be provided with more overflow weirs 22 than the number of specific gravity separators 3 connected to the downstream side. This provides the chromite ore separation and recovery facility 10 with the flexibility to flexibly accommodate changes in the number of specific gravity separators 3 installed.

[0036] Furthermore, as shown in Figure 4, it is preferable that the overflow weir 22 is configured such that the vertical cross-sectional shape of the flow path of the liquid phase that overflows the overflow weir and flows out of the tank is substantially rectangular. Because the flow path of the liquid phase that overflows the overflow weir and flows out of the tank is formed by a flat bottom surface and a pair of sides erected perpendicular to it, the relationship between the flow rate of the liquid phase overflowing the overflow weir and the head (height of the liquid surface of the overflow liquid) h maintains a linear correlation. Compared to an overflow weir with a triangular bottom surface that is not flat, the fluctuation in the amount of slurry discharged when the liquid surface height of the slurry in the tank fluctuates locally can be suppressed to a smaller fluctuation range.

[0037] Furthermore, as also shown in Figure 4, it is preferable to design the overflow weir 22 such that the relationship between the flow path width d of the overflow liquid channel and the head h is within the range of 0.5d ≤ h ≤ 2d. When the cross-sectional shape of the overflow liquid channel in the overflow weir 22 is a rectangle with a flat bottom, if h exceeds 2d, the flow velocity of the discharged slurry increases, and it becomes necessary to take measures to prevent wear of the channel. On the other hand, if h is less than 0.5, local fluctuations in the liquid level of the slurry in the tank have a large effect on the flow velocity of the discharged slurry, making it difficult to distribute the slurry evenly.

[0038] The slurry discharged from each overflow weir 22A, 22B, 22C, and 22D is transported through the downstream slurry transport pipes 21 (21A, 21B, 21C, 21D) to multiple downstream specific gravity separators 3 (3A, 3B, 3C, 3D).

[0039] [Specific gravity separator] A specific gravity separation device is a device that separates ore in a slurry using a specific gravity separation process that separates the ore based on the difference in gravity (specific gravity of the particles). This process concentrates the portion containing particles with a higher specific gravity, further promoting the concentration of chromium components, and then separates and recovers the high-chromium grade slurry.

[0040] Specifically, a "density separator" and / or a "spiral concentrator" can be preferably used as the specific gravity separation device. A "density separator" is a known device in which slurry is supplied from the top of the device and the specific gravity separation of the slurry is performed by the upward flow of injected water (teeter water (TW)) injected from the bottom of the device (see, for example, Japanese Patent Application Publication No. 2017-600930).

[0041] Furthermore, a "spiral concentrator" is a separation device equipped with a slurry channel that is a spiral-shaped inclined slide. Mineral particles with different specific gravities mixed in the slurry introduced into the spiral concentrator are separated by the difference in gravity as they flow through the slurry channel, which is a spiral-shaped inclined slide, and the coarse and heavy chromite ore (Conc) is recovered from the innermost concentrate (Conc) basin.

[0042] [Dilution water supply device] The dilution water supply device 4 is a device that supplies dilution water to adjust the slurry concentration to an appropriate range for the slurry that is separated and recovered in the classification processing device 1 and sent to the slurry relay tank 2. Various known water supply devices with the required water supply capacity can be used as the dilution water supply device 4. However, a unique feature of the separation and recovery equipment 10 is that the dilution water supply device 4 is configured to be able to directly inject an appropriate amount of dilution water into the slurry flow pipe 15, which is the flow pipe for the slurry that is separated and recovered in the classification processing device 1 and sent to the slurry relay tank 2. Specifically, the dilution water supply device 4 and the slurry flow pipe 15 are connected by a dilution water supply pipe 41, and the dilution water passes through the dilution water supply pipe 41 to the slurry flow pipe 15 and is injected directly into the pipe.

[0043] <Method for recovering chromite ore> The method for recovering chromite ore according to the present invention (hereinafter also simply referred to as the "chromite ore recovery method") is performed as a step to recover chromite ore in parallel with the execution of the ore slurry processing step S2, which is a part of the flow of the "wet smelting method for nickel oxide ore" shown in Figure 5. The recovery of chromite ore performed in the ore slurry processing step S2 is usually carried out in a procedure that performs processing with multiple types of physical separation devices, but the "chromite ore recovery method" is a recovery method that is suitable when the specific gravity separation step, which is one of the physical separation device processing performed in the process, is carried out by multiple specific gravity separation devices installed in parallel. Furthermore, it is preferable to perform the "chromite ore recovery method" using the "chromite ore separation and recovery equipment" of the present invention, which has been described in detail above.

[0044] In the "Wet Smelting Method for Nickel Oxide Ore," the process of recovering chromite ore in parallel with the ore slurry processing step S2 is usually carried out sequentially, with only the classification step S21, the specific gravity separation step S25, and the magnetic separation step S26 being performed among the steps shown in Figure 6. In contrast, the "Chromite Ore Recovery Method" is characterized by carrying out the specific gravity separation step S25 using multiple parallel-installed specific gravity separation devices as shown in Figure 1, and also by adding two additional steps, the slurry concentration adjustment step S22 and the slurry distribution step S23, as essential intermediate processing steps between the classification step S21 and the specific gravity separation step S25, as shown in Figure 6.

[0045] [Classification process] Classification step S21 is a step in which the nickel oxide ore slurry is classified according to the particle size difference of the particles contained in the ore slurry. In this step, the mixture containing goethite is separated as overflow (O / F) and the mixture containing chromite ore is separated as underflow (U / F). As described above, a hydrocyclone can be preferably used as the classification apparatus for classification step S21 in the "Method for recovering chromite ore".

[0046] [Slurry concentration adjustment process] The slurry concentration adjustment step S22 is a step in which an appropriate amount of diluent water is injected into the slurry that has been classified to the coarse-grain side in the classification step S21 and is fed into the downstream slurry distribution step S23 to adjust the slurry concentration. The amount of diluent water injected into the slurry is the amount necessary and sufficient to maintain the slurry concentration (concentration of solids in the slurry) in the range of 35% to 40%. If the slurry concentration is higher than the above concentration range, a high-load type agitator is required, which is undesirable from an economic standpoint. On the other hand, if the slurry concentration is lower than the above concentration range, the load on the agitator is reduced, but the tank capacity becomes larger, which is a drawback. Furthermore, if the slurry concentration is within the above range, due to the viscosity of the slurry, sedimentation separation in the tank is unlikely to occur as long as stirring continues, and the uniformity of the slurry is easier to maintain.

[0047] [Slurry distribution process] The slurry distribution step S23 is a step in which the slurry, whose slurry concentration has been appropriately adjusted in the slurry concentration adjustment step S22, is distributed to multiple slurry channels via a slurry relay tank having multiple overflow weirs as slurry outlets. It is preferable to use the slurry relay tank 2, which constitutes the chromite ore separation and recovery equipment of the present invention, as described in detail above, as the slurry relay tank.

[0048] Furthermore, in the "method for recovering chromite ore," when using a slurry relay tank 2 as the slurry relay tank for the slurry distribution step S23, in which the cross-sectional shape of the overflow liquid flow path in the overflow weir 22 can be a rectangle with a flat bottom, it is preferable to perform the "method for recovering chromite ore" within the range of operating conditions in which the relationship between the flow path width d of the overflow liquid flow path and the head h can be maintained in the range of 0.5d ≤ h ≤ 2d.

[0049] [Gravity separation process] The specific gravity separation step S25 is a step in which a high-chromium concentration slurry, which has had its chromium content further concentrated, is separated and recovered by specific gravity separation treatment from the slurry distributed to each slurry channel in the slurry distribution step S23, using a plurality of specific gravity separation devices installed in parallel. As described above, a "density separator" and / or a "spiral concentrater" can be preferably used as the specific gravity separation device for the specific gravity separation step S25 in the "method for recovering chromite ore".

[0050] [Magnetic beneficiation process] The magnetic separation process S26 is a process in which magnetite ore is removed from chromite ore, which has been concentrated with chromium components by the specific gravity separation process S25, by magnetic separation treatment, thereby reducing the iron content. Since magnetite ore (Mag) is removed, the product becomes non-magnetized material (Non-Mag).

[0051] <Wet smelting method for nickel oxide ore> The "chromite ore separation and recovery equipment" and "chromite ore recovery method" of the present invention, as described in detail above, are suitable separation and recovery equipment and recovery method as technical means for carrying out a partial process to recover chromite ore within the flow of a wet smelting process using nickel oxide ore as a raw material (hereinafter referred to as the "wet smelting method for nickel oxide ore"). Below, the "wet smelting method for nickel oxide ore," which is the overall process in which the present invention can be carried out as a partial process, will be described.

[0052] [Ore processing process] The ore processing step S1 is a step in which nickel oxide ore is mixed with water to form a nickel oxide ore slurry. In this specification, the ore slurry, which is a mixture of nickel oxide ore and water, is referred to as "nickel oxide ore slurry".

[0053] [Ore slurry processing process] The ore slurry processing step S2 is a pretreatment step for the ore slurry to be subjected to the leaching step S3, in which foreign matter is removed from the nickel oxide ore slurry and the ore particle size is adjusted. The "chromite ore recovery method" of the present invention can be performed as a process to separate and recover chromium from the ore slurry, which is the target material for processing (chromite ore recovery step S2 (see Figure 6)) in the ore slurry processing step S2, which is performed as a partial step of the "wet smelting method for nickel oxide ore," as shown in Figure 5.

[0054] [Leaching process] The leaching process S3 is a process in which valuable components such as nickel and cobalt are leached from the ore slurry with sulfuric acid using an autoclave or the like to obtain a leaching slurry.

[0055] [Solid-liquid separation process] The solid-liquid separation step S4 is a step in which the above-mentioned leaching slurry is separated into a leaching liquid containing nickel and cobalt and a leaching residue slurry using a multi-stage thickener or the like.

[0056] [Neutralization process] The neutralization step S5 is a step in which the above leachate is separated into a mother liquor containing nickel and a neutralized sediment slurry.

[0057] [Zinc removal process] The zinc removal step S6 is a step in which a sulfidating agent is added to the mother liquor described above to separate it into a mother liquor for nickel recovery and a zinc sulfide precipitate containing zinc sulfide.

[0058] [Sulfurization process] The sulfidation step S7 is a step in which a sulfidating agent is added to the mother liquor used for nickel recovery, separating it into a mixed sulfide containing nickel and cobalt (Ni, Co mixed sulfide) and a poor liquid. This poor liquid is ultimately sent to the final neutralization step S8, which is a downstream step, but as shown in Figure 5, part or all of it can also be used as washing water for the leaching residue in the solid-liquid separation step S4.

[0059] [Final neutralization process] The final neutralization step S8 is a process in which the leachate residue slurry separated in the solid-liquid separation step S4 is neutralized to a pH of approximately 8 to 9 to obtain the final neutralization residue. This final neutralization residue is stored in the tailing dam.

[0060] As explained above, the "wet smelting method for nickel oxide ore" is an overall process that includes the ore processing step S1, the ore slurry processing step S2, the leaching step S3, the solid-liquid separation step S4, the neutralization step S5, the zinc removal step S6, the sulfidation step S7, and the final neutralization step S8. The "chromite ore recovery method" of the present invention is a partial process that can be implemented as the ore slurry processing step S2 within the flow of such an overall process, and the "chromite ore separation and recovery equipment" of the present invention is suitable industrial equipment for implementing such a "chromite ore recovery method". [Examples]

[0061] The present invention will be further described below with reference to examples, but the present invention is not limited in any way by these examples.

[0062] <Example 1> In the chromite ore separation and recovery facility 10, which has the configuration shown in Figure 1, nickel oxide ore slurry is supplied to the classification treatment device (hydrocyclone) 1, and underflow (coarse grain; solid content concentration 60%, flow rate 55 m³) is used. 3 We obtained ( / h) and overflow (fine particles). The underflow was allowed to flow naturally down through the slurry transfer pipe 15 to the slurry transfer tank 2 installed in the lower section. Then, the dilution water (47m) was supplied through the dilution water supply pipe 41 connected in the middle of the slurry transfer pipe 15. 3 The slurry was added by injecting it into the slurry flow pipe 15, and the slurry concentration in the slurry relay tank 2 was adjusted to 40%. The capacity of slurry relay tank 2 is 2 m³ 3The overflow weir consists of four overflow weirs 22 (22A, 22B, 22C, 22D) spaced at 90-degree intervals. Each weir has a roughly rectangular vertical cross-sectional shape with a flat bottom, a channel width (d) of 75 mm, and a channel height (H) of 75 mm. The stirring power is 1.5 kW / m². 3 The slurry in the tank was stirred using a stirrer at a rotation speed of 180 RPM. Four specific gravity separation devices 3 were installed, and slurry was distributed from the slurry relay tank 2 to all four specific gravity separation devices 3 (3A, 3B, 3C, 3D). During the implementation described above, the flow rate and concentration of the slurry discharged from each overflow weir were measured. The difference between the maximum and minimum slurry flow rates was 5.8%, indicating that the expected uniform distribution of slurry was achieved. Similarly, the difference between the maximum and minimum slurry concentrations was 3.0%, indicating that a slurry with uniform concentration was distributed.

[0063] (Example 2) The amount of liquid supplied to the classification device (hydrocyclone) 1 was set to half the amount supplied in Example 1, and the slurry was distributed to only two specific gravity separators (3A, 3D) from only two diagonally located overflow weirs (22A, 22D) using the same procedure. A closing plate was attached to the unused overflow weirs (22B, 22D) to form an overflow weir closing mechanism, and the slurry was distributed with the discharge of slurry stopped. During the implementation described above, the flow rate and concentration of the slurry discharged from each overflow weir were measured. The difference between the maximum and minimum slurry flow rates was 6.6%, indicating that the expected uniform distribution of slurry was achieved. Furthermore, the difference between the maximum and minimum slurry concentrations was 3.6%, indicating that a slurry with uniform concentration was distributed.

[0064] (Example 3) In the same procedure as in Example 2, slurry was distributed from only two adjacent overflow weirs (22A, 22C) to only two specific gravity separators (3A, 3C). The overflow weirs not in use (22B, 22D) were closed off by installing closure plates as described above to stop the discharge of slurry. During the implementation described above, the flow rate and concentration of the slurry discharged from each overflow weir were measured. The difference between the maximum and minimum slurry flow rates was 7.4%, indicating that the expected uniform distribution of slurry was achieved. Furthermore, the difference between the maximum and minimum slurry concentrations was 5.2%, indicating that a slurry with uniform concentration was distributed.

[0065] (Comparative Example 1) We attempted to distribute the slurry using the same procedure as in Example 1, except that instead of injecting the same amount of diluting water used to adjust the slurry concentration into the slurry transport pipe 15, we added the same amount of diluting water as in Example 1 directly to the slurry transfer tank. However, the hydrocyclone underflow became clogged in the slurry transport pipe 15, forcing us to interrupt operations.

[0066] From the above results, it can be seen that, according to the present invention, in a chromite ore separation and recovery facility that includes a configuration in which separation devices of the same type are installed in parallel, the slurry can be stably and evenly distributed from the upstream device to multiple devices arranged in parallel downstream. [Explanation of Symbols]

[0067] 1. Classification Processing Device (Hydrocyclone) 11 Tapered cylindrical section 12. Supply piping 13 Overflow outlet 14. Underflow outlet (spigot) 15. Slurry flow pipe (U / F) 16. Slurry flow pipe (O / F) 2. Slurry relay tank 21 (21A, 21B, 21C, 21D) Slurry flow pipe 22(22A, 22B, 22C, 22D) Overflow weir 23 Tank body 24 Stirrer 3(3A, 3B, 3C, 3D) Specific gravity separator 4. Dilution water supply device 41 Dilution water supply pipe 10. Chromite ore separation and recovery equipment S1 Ore Processing Process S2 Ore slurry processing process (chromite ore recovery process) S3 leaching process S4 Solid-liquid separation process S5 Neutralization process S6 Zinc removal process S7 Sulfurization process S8 Final neutralization step S21 Classification process S22 Slurry concentration adjustment process S23 Slurry distribution process S24 Specific gravity separation process S25 Magnetic beneficiation process

Claims

1. A classification apparatus for separating and recovering a chromium-containing slurry from an ore slurry based on the particle size difference of the particles constituting the ore slurry, and a plurality of specific gravity separation apparatuses arranged downstream of the classification apparatus for separating and recovering a high-chromium concentration slurry from the slurry separated and recovered by the classification apparatus, in which the chromium content has been further concentrated by specific gravity separation. A chromite ore separation and recovery facility equipped with, It further includes a slurry relay tank and a dilution water supply device. The slurry relay tank is installed between the classification apparatus and the specific gravity separation apparatus, and has an agitator and a plurality of overflow weirs that distribute and discharge the agitated slurry toward the specific gravity separation apparatus, and the difference between the maximum and minimum flow rates of the slurry discharged from the plurality of overflow weirs is 7.4% or less. A dilution water supply pipe extending from the dilution water supply device is connected to a slurry flow pipe connecting the classification processing device and the slurry relay tank. A facility for separating and recovering chromite ore.

2. The overflow weir is equipped with an overflow weir closing mechanism that can stop the discharge of slurry as needed. The number of the overflow weirs is greater than the number of gravity separation devices connected to the downstream side of the slurry relay tank. The chromite ore separation and recovery apparatus according to claim 1.

3. The cross-sectional shape of the channel through which the overflow liquid overflowing the overflow weir flows is substantially rectangular, and the bottom surface of the channel is flat. A chromite ore separation and recovery apparatus according to claim 1 or 2.

4. The classification apparatus is a hydrocyclone, and the specific gravity separation apparatus is a density separator and / or spiral concentrator. A chromite ore separation and recovery apparatus according to any one of claims 1 to 3.

5. A method for recovering chromite ore by separating and recovering chromite ore from nickel oxide ore slurry, A classification process that separates the slurry based on the difference in particle size of the contained particles, In the classification process, a slurry concentration adjustment step is performed in which dilution water is injected into the slurry that has been classified to the coarse particle side to adjust the slurry concentration. In the slurry concentration adjustment step, the slurry whose slurry concentration has been adjusted is distributed to a plurality of specific gravity separation devices and discharged via a slurry relay tank having a stirrer and a plurality of overflow weirs as slurry discharge ports, and the difference between the maximum and minimum flow rates of the slurry discharged from the plurality of overflow weirs is 7.4% or less in the slurry distribution step. A specific gravity separation step is performed to separate and recover a high-chromium concentration slurry, which has a further concentrated chromium content, from each of the slurries distributed in the slurry distribution step, using the specific gravity separation device. It includes, A method for recovering chromite ore, wherein in the slurry concentration adjustment step, the amount of dilution water injected is adjusted so that the slurry concentration introduced into the slurry distribution step is 35% or more and 40% or less.

6. The cross-sectional shape of the channel of the overflow weir through which the overflow liquid overflowing the weir flows is substantially rectangular, and the bottom surface of the channel is flat. The slurry distribution process is performed while maintaining the relationship between the channel width d of the channel and the height h of the overflow liquid in the channel within the range of 0.5d ≤ h ≤ 2d. The method for recovering chromite ore according to claim 5.

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