Ore slurry manufacturing method and metal smelting method

Abstract

To provide a method for suppressing excessive viscosity increase of a slurry, which causes poor transfer, at a cost lower than conventional means, in production of the ore slurry for obtaining the ore slurry from raw material ore.SOLUTION: A method for producing an ore slurry comprises: a particle size distribution measurement step S11 in which particle size distribution is measured for each raw material ore group for raw material ores that have been grouped into a plurality of groups in advance; a mixing ratio determining step S12 for determining a mixing ratio of the raw materials ores for each raw material ore group; a blending step S13 for blending the raw material ores on the basis of the mixing ratio; a classification step 14 for obtaining a coarse ore slurry made of ore particles of under size by removing oversized ore particles; and an ore slurry concentration step S15 in which water contained in the crude ore slurry is separated and removed to concentrate ore components, and in the mixing ratio determination step S12, the mixing ratio is determined such that an average particle size after blending becomes a predetermined value or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing an ore slurry, a metal refining method, and a method for producing a nickel oxide ore. More specifically, the present invention relates to an "ore slurry production method" and a "metal refining method" that can suppress an increase in the viscosity of the ore slurry. [Background technology]

[0002] In recent years, high-pressure acid leaching (hereinafter also referred to as the "HPAL method"), a hydrometallurgical process, has been used as a smelting method for recovering nickel and cobalt from nickel oxide ore, which contains approximately 1.0 to 2.0% nickel and 0.1 to 0.5% cobalt, respectively, based on the total amount.

[0003] The "HPAL method" is a leaching method in which sulfuric acid is added to a slurry of nickel oxide ore, and leaching is performed under high temperature and pressure to obtain a leachate containing nickel and cobalt. A widely used metal refining method includes a leaching step using the "HPAL method," a neutralization step to form a neutralized precipitate slurry containing impurity elements and a mother liquor for nickel recovery, and a sulfurization step to form a mixed nickel-cobalt sulfide and a barren liquor from the mother liquor for nickel recovery (see Patent Document 1).

[0004] In the above-described metal refining method, raw ore, such as nickel oxide ore, is subjected to a crushing and classification process, which involves crushing and multi-stage classification (sieving), and an ore slurry concentration process, which concentrates the ore components, to produce an ore slurry, which is then introduced into the leaching process (see Patent Documents 2 and 3). However, in the process of producing this ore slurry, variations in the particle size of the raw ore introduced can result in the inclusion of extremely small ore particles, resulting in an excessively high viscosity of the resulting ore slurry. This is thought to be because, in an ore slurry consisting of extremely small ore particles, the fine ore particles aggregate due to a certain cohesive force, and water is trapped between the aggregated particles, reducing the apparent amount of solvent in the slurry and resulting in an increase in the viscosity of the ore slurry.

[0005] If the viscosity of the ore slurry increases excessively, for example, when the ore slurry is transported to a metal refining process, it cannot be transported effectively using a normal transfer pump, and problems such as the slurry adhering to piping occur. If such poor transport of the ore slurry occurs in a metal refining process, operations must be temporarily stopped to remove the slurry adhering to the piping, which significantly reduces operational efficiency.

[0006] One possible technical solution to avoid excessive fineness of raw ore and the resulting excessive increase in viscosity of the ore slurry would be to add a new process to remove excessively fine ore particles as the final stage of the crushing and classification process. However, implementing such a solution would increase the cost of installing new equipment. In addition, such a solution would also pose a significant risk of reducing the effective utilization of ore resources by increasing the amount of ore rejected in the crushing and classification process.

[0007] Therefore, as another technical means for solving the above problems, a "method for producing an ore slurry" has been proposed in which a portion of the oversized ore particles removed in the crushing and classification process is recharged into a solid-liquid separator (see Patent Document 4). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-350766 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-173967 [Patent Document 3] Japanese Patent Application Publication No. 11-124640 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-95998 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method described in Patent Document 4, in which a portion of the oversized ore particles is recharged into a solid-liquid separator, requires a storage space for the oversized ore particles removed and recovered by classification. It also requires crushing equipment to adjust these oversized ore particles to particles of, for example, 20 to 100 μm. Therefore, implementing this method may also significantly increase equipment costs. Furthermore, mixing oversized ore particles with a high level of impurities increases the average impurity grade, which in turn increases the amount of material input, potentially contributing to increased production costs.

[0010] The present invention has been made in view of the above-mentioned circumstances, and has an object to suppress an excessive increase in the viscosity of the slurry, which causes transport problems, at a lower cost than conventional means in producing an ore slurry from a raw ore such as nickel oxide ore. [Means for solving the problem]

[0011] As a result of extensive research into achieving the above-mentioned object, the inventors have discovered that in a method for producing an ore slurry from raw ore, the above-mentioned problems can be solved by grouping the raw ore according to particle size distribution and optimizing the blend ratio of each group, and have completed the present invention. Specifically, the present invention provides the following.

[0012] (1) A method for producing an ore slurry from raw ore, the method comprising: a particle size distribution measurement step for measuring the particle size distribution of each raw ore group of the raw ore, which has been previously divided into a plurality of groups; a mixing ratio determination step for determining a mixing ratio of the raw ores for each raw ore group; a blending step for blending the raw ores based on the mixing ratio; a classification step for classifying the raw ores at a predetermined classification point to remove oversized ore particles and obtain a coarse ore slurry consisting of undersized ore particles; and an ore slurry concentration step for separating and removing water contained in the coarse ore slurry to concentrate the ore components, wherein in the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw ores after blending is equal to or greater than a predetermined value.

[0013] According to the method for producing ore slurry (1), in producing an ore slurry from a raw ore such as nickel oxide ore, it is possible to suppress an increase in the viscosity of the slurry, which causes transport problems, at a lower cost than conventional methods.

[0014] Furthermore, even for the same type of raw ore, such as nickel oxide ore, there are usually certain differences in physical properties, such as average particle size, between brands, i.e., between sources. Furthermore, even for the same source, there is inevitably a certain degree of variation in physical properties between incoming units, i.e., between lots. Such variations in physical properties between brands and lots of raw ore have traditionally led to excessive increases in the viscosity of the ore slurry and variations in the quality of the final product. In contrast, the ore slurry manufacturing method (1) skillfully utilizes the variations in physical properties of raw ore, such as between brands, as "groups" for the blending process, thereby improving the productivity of the entire process and contributing to the effective use of raw ore and the stability of the quality of the final product.

[0015] (2) In the method for producing an ore slurry according to (1), in the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw ore after blending is a particle size that does not cause transportation problems due to an increase in viscosity of the ore slurry.

[0016] According to the method for producing an ore slurry of (2), an increase in the viscosity of the ore slurry can be suppressed, and a decrease in productivity due to poor transport of the slurry can be avoided.

[0017] (3) In the method for producing an ore slurry according to (1), in the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw ores after blending becomes a particle size that makes the yield stress of the ore slurry 200 Pa or less.

[0018] According to the method for producing an ore slurry of (3), in a transfer pump commonly used in metal refining processes using an ore slurry, the average particle size of the raw ore after blending is controlled by optimizing the mixing ratio during blending, using the particle size at which the yield stress of the ore slurry exceeds 200 Pa as an index, thereby suppressing an increase in the viscosity of the ore slurry and preventing transfer problems, etc. At operational sites, when expressing the viscosity of an ore slurry, the value of the yield stress (unit: "Pa") is generally used as an alternative index (see Patent Document 4), and in this specification, the yield stress of the ore slurry is also used as an alternative index for expressing the viscosity of the ore slurry as described above, as necessary.

[0019] (4) The method for producing an ore slurry according to any one of (1) to (3), wherein in the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw ore after blending is 8.0 μm or more.

[0020] When carrying out the method for producing an ore slurry according to any one of (1) to (3), including when nickel oxide ore is used as the raw ore, in many cases, the yield stress of the ore slurry will exceed 200 Pa when the particle size of the ore is less than 8.0 μm. Therefore, according to the method for producing an ore slurry according to (4), by optimizing and managing the blending ratio so that the average particle size of the raw ore after blending is 8.0 μm or more, it is possible to suppress an increase in the viscosity of the ore slurry and prevent problems such as poor transport.

[0021] (5) The method for producing an ore slurry according to any one of (1) to (3), wherein the raw ore is a nickel oxide ore.

[0022] According to the method for producing an ore slurry of (5), the above-mentioned effects of the method for producing an ore slurry of any one of (1) to (3) can be enjoyed, and an increase in the viscosity of the ore slurry can be suppressed, thereby effectively preventing poor transport of the ore slurry and preventing a decrease in productivity due to poor transport of the ore slurry in a metal refining process for obtaining nickel and cobalt from nickel oxide ore.

[0023] (6) A metal refining method comprising a leaching step of adding the ore slurry produced by the method for producing an ore slurry according to any one of (1) to (3) to sulfuric acid to obtain a leachate containing a target metal under high temperature and high pressure.

[0024] According to the metal refining method of (6), the above-mentioned effects of the method for producing an ore slurry according to any one of (1) to (3) can be enjoyed, and an increase in the viscosity of the ore slurry can be suppressed. This makes it possible to effectively prevent poor transport of the ore slurry without installing new equipment, and to prevent a decrease in productivity due to poor transport of the ore slurry in a metal refining process carried out using a high-temperature pressure acid leaching method (HPAL method) using sulfuric acid. [Effects of the Invention]

[0025] According to the present invention, in producing an ore slurry from a raw ore such as nickel oxide ore, it is possible to suppress an excessive increase in the viscosity of the slurry, which causes transport problems, at a lower cost than conventional means. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a process diagram of a hydrometallurgical method for smelting nickel oxide ore, which is a typical metal smelting process to which the "ore slurry manufacturing method" and "metal smelting method" of the present invention can be applied. [Figure 2] 1 is a process diagram of the "method for producing an ore slurry" of the present invention. [Figure 3] 1 is a graph illustrating the relationship between slurry density and viscosity when two types of raw ore having different particle sizes are blended. [Figure 4] 1 is a logarithmic graph illustrating the relationship between slurry density and viscosity when two types of raw ore with different particle sizes are blended. [Figure 5] 1 is a performance curve showing the relationship between the viscosity of the ore slurry and the discharge amount of a pump for sending the ore slurry to a leaching process. DETAILED DESCRIPTION OF THE INVENTION

[0027] Specific embodiments of the "method for producing an ore slurry" and the "method for refining a metal" of the present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, and various modifications are possible within the scope of the present invention.

[0028] <Method for producing ore slurry> The method for producing an ore slurry of the present invention (hereinafter also simply referred to as the "method for producing an ore slurry") is a method for producing, from raw ore, an "ore slurry" to be input into a downstream process such as a "leaching process" in various metal smelting processes, such as metal smelting for recovering nickel and cobalt from nickel oxide ore.

[0029] This "method for producing an ore slurry" is a suitable process for carrying out an ore slurry production step S1, which is a substep of the "method for hydrometallurgy of nickel oxide ore" shown in Fig. 1. As shown in Fig. 2, this "method for producing an ore slurry" sequentially performs the steps of a particle size distribution measurement step S11, a mixing ratio determination step S12, a blending step S13, a classification step S14, and an ore slurry concentration step S15, thereby stably producing an ore slurry having an appropriate viscosity that does not cause transport problems from a raw ore such as nickel oxide ore.

[0030] The "method for producing an ore slurry" of the present invention is not limited to the above-mentioned nickel oxide ore metal, but can be applied to the processing of various raw ores containing valuable metals, such as copper oxide ore containing copper.

[0031] [Particle size distribution measurement process] The particle size distribution measurement step S11 is a step of measuring the particle size distribution of each raw ore group for raw ore that has been grouped into a plurality of groups in advance. Here, each raw ore group can be composed of a delivery lot or the like in which a fixed amount of the same type of ore is grouped together, but it is preferable that the raw ore groups be grouped by raw ore of the same brand (raw ore mined from the same ore area) that has relatively high uniformity in properties.

[0032] The particle size distribution of each raw ore group is measured by adding pure water as a solvent to a sample taken from each raw ore group in an amount sufficient to provide statistical data, placing the sample in a particle size distribution analyzer, and measuring the average particle size (50% diameter: D50). As the particle size distribution analyzer, various known particle size distribution analyzers, such as a Microtrac particle size analyzer, can be used.

[0033] In this particle size distribution measurement step S11, it is preferable to perform pretreatment prior to particle size measurement by sieving the sample to remove ore particles of a certain particle size or larger, along with impurities such as pebbles and tree roots. The "certain particle size or larger" that serves as the classification point in this pretreatment is preferably the same as the particle size that serves as the classification point in the subsequent classification step S14. More specifically, this pretreatment can be performed by hand sieving with a mesh of an appropriate size (for example, 1.7 mm to 2.0 mm).

[0034] [Mixing ratio determination process] The blending ratio determination step S12 is a step of determining the blending ratio of raw ores for each raw ore group. In this blending ratio determination step S12, the blending ratio is determined so that the "average particle size (50% D) of the raw ores after blending" in the subsequent blending step S13 is equal to or greater than a predetermined value. In this way, the raw ores are blended to an average particle size equal to or greater than a value that does not cause an excessive increase in viscosity, thereby inhibiting physical aggregation of fine ore particles. This suppresses moisture retention between particles, resulting in a reduced viscosity of the concentrated slurry. The specific value of the "average particle size (50% D) of the raw ores after blending" in the blending step S13 varies to some extent depending on the various operating conditions at the operational site where each process is performed and the type of raw ore being handled. However, as demonstrated in the examples below, for example, when nickel oxide ore is used as the raw ore, a preferred target predetermined value for the average particle size of the raw ores after blending is 8.0 μm or greater.

[0035] Regarding the "average particle size of the raw ores after blending," the present invention can be implemented by considering the average value calculated by weighting the average particle sizes of the raw ores for each group before blending, which differ from one another, based on the above-mentioned mixing ratio, as the "average particle size of the raw ores after blending" or an approximate value thereof.

[0036] Furthermore, in the mixing ratio determination step S12, it is more preferable to determine the mixing ratio of the blend, taking into account the "relationship between the viscosity of the ore slurry and the transport capacity of the pump" (see FIG. 5), so that the "average particle size of the raw ore after blending" is a particle size that does not cause the above-mentioned transport problems due to an increase in the viscosity of the ore slurry.

[0037] Furthermore, in general, in many metal refining processes, pumps used to transport ore slurries are prone to the above-mentioned transport problems when the yield stress of the ore slurry exceeds 200 Pa. Therefore, the "average particle size of the raw ores after blending" can be determined so that the yield stress of the ore slurry is 200 Pa or less.

[0038] [Blending process] The blending step S13 is a step of blending raw ore, which has been grouped by ore area unit (ore type) or by incoming lot, based on the "mixing ratio" determined in the mixing ratio determination step S12. The mixing process for this blending can be performed mechanically using heavy machinery such as a shovel loader or a wheel loader.

[0039] [Classification process] The classification step S14 is a step in which the blended raw ore is classified at a predetermined classification point to remove oversized ore particles and obtain a coarse ore slurry consisting of undersized ore particles. The classification process in the classification step S14 is preferably carried out by first crushing the blended raw ore using a crusher such as a general ball mill, rod mill, or AG mill, and then classifying the ore at the predetermined classification point by sieving using a grizzly or vibrating sieve to remove oversized ore particles.

[0040] Specifically, for example, the classification point can be set to about 1.4 mm, and the ore can be classified by sieving using a sieve with 1.4 mm openings. By performing classification in this manner, ore particles remaining on the sieve with particle sizes larger than 1.4 mm, i.e., oversized ore particles, are removed along with pebbles, tree roots, etc.

[0041] On the other hand, the ore particles that pass through the sieve openings (below the mesh) are small ore particles with a particle size of 1.4 to 2.0 mm or less, i.e., undersized ore particles. In the classification process S14, these undersized ore particles are collected and made into coarse ore slurry, which is transferred to the next process, the ore slurry concentration process S15.

[0042] [Ore slurry concentration process] The ore slurry concentration step S15 is a step in which the above-mentioned coarse ore slurry obtained in the classification step S14 is charged into a solid-liquid separator, the water contained in the coarse ore slurry is separated and removed, the ore components are concentrated, and an ore slurry is obtained.

[0043] Specifically, in the ore slurry concentration step S15, the coarse ore slurry is charged into a solid-liquid separator such as a thickener, and the solid components are allowed to settle and removed from the bottom of the separator, while the supernatant water is allowed to overflow from the top of the separator. This solid-liquid separation process reduces the water content in the coarse ore slurry and concentrates the ore components in the slurry, thereby obtaining an ore slurry with a solid concentration of, for example, about 40% by weight.

[0044] It is preferable to use the above-mentioned thickener as the solid-liquid separator. In this case, the higher the viscosity of the coarse ore slurry fed into the solid-liquid separator (thickener), the slower the settling speed of the ore particles in the separator, which tends to result in a lower viscosity of the discharged ore slurry. This helps to reduce the risk of the ore slurry becoming too viscous, and as a result, the effects of the present invention can be more stably achieved.

[0045] The viscosity of the ore slurry produced through the above processes can be measured using, for example, a rheometer. It can also be calculated as the yield stress using a slump test. The slump test is a well-known method in commercial ore slurry processing plants and is similar to the concrete slump test method (JIS A 1101). The slump test involves filling a cylindrical pipe with slurry, placing it upright on a horizontal surface, and gently removing the pipe. The slurry column expands and decreases in height due to its own weight. Specifically, if the height of the cylindrical pipe (≒ the height of the slurry column immediately after removal from the pipe) is H0, the height of the slurry after deformation due to its own weight is H1, and the rate of change is S, then S is expressed by the following equation (1). The yield stress (Pa) can be calculated by substituting the slurry density γ (g / L) into the following equation (2): S = (H0 - H1) / H0 (1) Yield stress [Pa] = 0.5 × (1-S 0.5 )×γ×0.98×H0 (2)

[0046] <Metal smelting method (hydrometallurgy method for nickel oxide ore)> The "method for producing an ore slurry" of the present invention, which has been described in detail above, is an industrial process, one example of a preferred embodiment of which is implemented as an "ore slurry production step S1" for producing an ore slurry from a raw ore in the course of a hydrometallurgical process using nickel oxide ore as the raw ore (hereinafter referred to as a "hydrometallurgical method for producing a nickel oxide ore"). Below, a "method for producing a nickel oxide ore hydrometallurgical process" that is an overall process that can be carried out as a partial process of the "method for producing an ore slurry" of the present invention will be described.

[0047] As shown in FIG. 1 , the "hydrometallurgical method for producing nickel oxide ore" is a process that sequentially includes an ore slurry production step S1 in which an ore slurry is produced from nickel oxide ore; a leaching step S2 in which nickel and cobalt are leached from the obtained ore slurry to obtain a leachate slurry; a solid-liquid separation step S3 in which the obtained leachate slurry is separated into a leachate and a leach residue; a neutralization step S4 in which the obtained leachate is neutralized and separated into a mother liquor for recovering nickel and a neutralized precipitate slurry; and a sulfurization step S5 in which hydrogen sulfide gas is blown into the sulfuric acid mother liquor to promote a sulfurization reaction and obtain a nickel-containing sulfide and a barren liquor.

[0048] [Ore slurry manufacturing process] The ore slurry production step S1 is a step of producing an ore slurry from a nickel oxide ore as a raw ore. By performing this ore slurry production step S1 by the "method for producing an ore slurry" of the present invention, an ore slurry can be stably produced in which an excessive increase in the slurry viscosity is suppressed, and the ore slurry can be efficiently transferred to the subsequent leaching step using a general transfer pump or the like without causing transfer problems or the like.

[0049] The nickel oxide ore mainly includes so-called laterite ores such as limonite ore and saprolite ore. The nickel content of laterite ore is usually 0.8 to 2.5% by weight, and is contained as hydroxide or magnesium silicate (magnesium silicate) mineral. The iron content is 10 to 50% by weight, and is mainly in the form of trivalent hydroxide (goethite), with some divalent iron contained in the magnesium silicate mineral. In addition to laterite ore, oxide ores containing valuable metals such as nickel, cobalt, manganese, and copper, such as manganese nodules found on the deep seabed, are also used.

[0050] [Leaching process] The leaching step S2 is a step of obtaining a leached slurry by leaching valuable components such as nickel and cobalt with sulfuric acid from the ore slurry obtained in the ore slurry production step S1 using an autoclave or the like. This leaching step S2 is preferably performed by a high-temperature pressure acid leaching method (HPAL method), in which the ore slurry is added to sulfuric acid and a leachate containing the target metals is obtained under high temperature and high pressure.

[0051] [Solid-liquid separation process] The solid-liquid separation step S3 is a step in which the leaching slurry is separated into a leachate containing nickel and cobalt and a leach residue using a multi-stage thickener or the like.

[0052] [Neutralization process] The neutralization step S4 is a step of separating the leachate into a mother liquor containing nickel and a neutralized precipitate slurry.

[0053] [Sulfurization process] The sulfurization step S5 is a step of adding a sulfurizing agent to the mother liquor for recovering nickel, and separating the mother liquor into a mixed sulfide containing nickel and cobalt (a mixed sulfide of Ni and Co) and a lean liquor.

[0054] In this sulfurization step S5, a nickel-containing sulfide (nickel sulfide) whose average particle size is adjusted to a predetermined size or more can be added as seed crystals to the sulfuric acid. This can reduce the concentration of fine suspended solids containing nickel in the overflow liquid during the sedimentation treatment for separating the sulfide slurry produced by the sulfurization reaction into a sulfide precipitate and a barren liquid, thereby increasing the amount of nickel that can be precipitated as sulfide and reducing nickel recovery loss. [Example]

[0055] The present invention will be further explained below with reference to examples, but the present invention is not limited to these examples in any way.

[0056] [Examples 1 to 3] Test production of ore slurry by the "method for producing ore slurry" of the present invention was carried out under the test conditions detailed below. Two types of nickel oxide ore, "Ore Type A" and "Ore Type B," were used as raw ores for "Group 1" and "Group 2," respectively.

[0057] (Particle size distribution measurement process) Sampling samples were taken from each of the raw ores (ore type A and ore type B) in "Group 1" and "Group 2." These samples were first sieved by hand with a 1.7-2.0 mm mesh to extract only the undersize particles. Purified water was added to the undersize particles as a solvent to create a slurry. This slurry was then loaded into a Microtrac particle size analyzer (9320-X100, manufactured by Nikkiso Co., Ltd.) as a sample for particle size measurement, and the particle size distribution of each raw ore (ore type A and ore type B) was measured. The results are shown in Table 1.

[0058] [Table 1]

[0059] (Mixing ratio determination process) and (Blending process) The raw ores of Group 1 (ore type A) and Group 2 (ore type B) having the particle size distributions shown in Table 1 were blended at two different mixing ratios as shown in Table 2 to obtain two types of blended raw ores as Examples 1 and 2. The raw ores used without blending were used as the raw ores of Comparative Examples 1 and 2.

[0060] [Table 2]

[0061] (Classification process) After crushing, the two types of blended raw ores in Examples 1 and 2 and the unblended raw ores in Comparative Examples 1 and 2 were classified to a classification point of 1.4 mm to remove oversized ore particles, and a coarse ore slurry consisting of undersized ore particles was obtained.

[0062] (Ore slurry concentration process) Next, the crude ore slurries obtained from the four types of blended raw ores in Examples 1 to 4 were poured into a pit with a diameter of about 25 m, a height of about 5 m, and a volume of about 2000 m. 3 The thickener has a flow rate of 250m 3 The ore slurries were charged for 1 / hour, and a concentration treatment was performed to remove water and concentrate the ore components. After the concentration treatment was completed, the resulting ore slurries were removed from the bottom of the thickener. For each of Examples 1 to 3, five or six ore slurry samples with different water removal rates were produced.

[0063] [Evaluation of ore slurry] The slurry density and viscosity were measured for each ore slurry sample obtained from the four types of blended raw ores in Examples 1 and 2 and Comparative Examples 1 and 2. The measurement results are shown in FIG.

[0064] 3, the slurry of Comparative Example 1, which is composed only of ore from Group 1 (ore type A) with a fine average particle size (50% D), has the highest viscosity at the same density. On the other hand, the slurry of Comparative Example 2, which is composed only of ore from Group 1 (ore type B) with a coarse average particle size (50% D), has the lowest viscosity at the same density.

[0065] Similarly, from FIG. 3, it can be seen that even when processing Group 1 ore (ore type A) with a fine average particle size (50% D), as in Examples 1 and 2, the viscosity of the slurry can be reduced by blending Group 1 ore (ore type B) with a coarse average particle size (50% D).

[0066] From Figure 4, which shows a logarithmic representation of Figure 3, the slurry density is 1.5 g / cm 3 When the viscosity at each ore mixing ratio is calculated backward, the viscosity of the ore slurry of Example 1 is 2175 mPa·s, while the viscosity of the ore slurry of Comparative Example 1 is 9638 mPa·s.

[0067] When the viscosity of each ore slurry obtained in Figure 4 is plotted on Figure 5, which is the capacity curve of the pump for sending the ore slurry to the next leaching process, the dischargeable slurry flow rate is as shown in Table 3. For the ore slurry of Comparative Example 1, the slurry flow rate is 220 m 3 / h, whereas in the ore slurry of Example 1, the slurry flow rate is 270 m 3 / h.

[0068] [Table 3]

[0069] From the above evaluation results, it can be seen that the method for producing an ore slurry of the present invention can suppress the increase in viscosity of the slurry, which causes transport problems, at a lower cost than conventional means in producing an ore slurry from a raw ore such as nickel oxide ore. Furthermore, it can be seen that the method can contribute to the effective use of raw ore and the stability of the quality of the final product in that it can improve the productivity of the entire process by skillfully utilizing the variations in the physical properties of the raw ore brands and lots as "groups" for the blending step. [Explanation of symbols]

[0070] S1 Ore slurry production process S2 leaching process S3 Solid-liquid separation process S4 Neutralization process S5 Sulfurization process S11 Particle size distribution measurement process S12 Mixing ratio determination process S13 Blending process S14 Classification process S15 Ore slurry concentration process

Claims

1. A method for producing an ore slurry from a raw ore, comprising: a particle size distribution measuring step of measuring a particle size distribution for each of the raw ore groups, the raw ore being grouped in advance into a plurality of groups; a mixing ratio determination step of determining a mixing ratio of the raw ores for each raw ore group; a blending step of blending the raw material ores based on the mixing ratio; a classification step of removing oversized ore particles to obtain a coarse ore slurry consisting of undersized ore particles; an ore slurry concentration step of separating and removing water contained in the crude ore slurry to concentrate the ore components, In the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw material ores after blending is equal to or greater than a predetermined value. A method for producing an ore slurry.

2. In the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw material ore after blending is a particle size that does not cause transportation problems due to an increase in viscosity of the ore slurry. The method for producing the ore slurry according to claim 1.

3. In the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw material ore after blending becomes a particle size such that the yield stress of the ore slurry is 200 Pa or less. The method for producing the ore slurry according to claim 1.

4. In the mixing ratio determination step, the mixing ratio is determined so that the average particle size of the raw material ore after blending is 8.0 μm or more. A method for producing an ore slurry according to any one of claims 1 to 3.

5. The raw ore is a nickel oxide ore. A method for producing an ore slurry according to any one of claims 1 to 3.

6. The method comprises a leaching step of adding the ore slurry produced by the method for producing an ore slurry according to any one of claims 1 to 3 to sulfuric acid under high temperature and high pressure to obtain a leachate containing the target metal. Metal smelting method.

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