Pretreatment method of nickel oxide ore slurry, wet smelting method of nickel oxide ore and thickener

Abstract

To provide a pretreatment method of a nickel oxide ore slurry (Ni slurry) capable of efficiently enhancing Solid% of Ni slurry, a wet smelting method of a Ni oxide ore using the Ni slurry after treatment, and a thickener.SOLUTION: A pretreatment method is for a wet smelting method that charges, together with a mineral acid, Ni slurry prepared by mixing a Ni oxide ore and water into a compression vessel to bleed Ni. The pretreatment method of Ni slurry charges Ni slurry to a thickener 1 before charging the Ni slurry into the compression vessel to solid-liquid separate the Ni slurry. The pretreatment method acts a magnetic power of magnetic flux density 0.1 T (tesla) or more onto Ni slurry containing 0.5 mass% or more magnetic compound derived from a Ni oxide ore to solid-liquid separate the Ni slurry.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydrometallurgical method for nickel oxide ore in which nickel oxide ore slurry is charged into a pressure vessel together with a mineral acid to extract nickel under high pressure, and more particularly to a pretreatment method for nickel oxide ore slurry in which the nickel oxide ore slurry is charged into a thickener before being charged into the pressure vessel to separate it into solid and liquid, a hydrometallurgical method for nickel oxide ore, and an improvement to the thickener used in these methods. [Background technology]

[0002] As a method for recovering nickel from low-grade nickel oxide ore, a hydrometallurgical process using the High Pressure Acid Leach (HPAL) method is known. In this hydrometallurgical process, the nickel oxide ore that is sent to the high pressure acid leaching process is crushed and classified in advance to a predetermined size or less using a crusher or wet sieve to make it easier to leach nickel, and then water or alcohol is added to make a slurry of the nickel oxide ore.

[0003] This nickel oxide ore slurry is often made by blending several types of nickel oxide ore so that the acid consumption in the high-pressure acid leaching process, the nickel concentration of the resulting leachate, and the concentrations of other impurities are in a predetermined ratio.

[0004] In addition, in the case of nickel oxide ore slurry, if the solid content ratio (hereinafter sometimes referred to as "solid %") in the ore slurry constituting the ore slurry is high, the amount of nickel passing through per unit time in the high-pressure acid leaching process increases, which is expected to increase the production volume per unit facility, reduce operating costs, and improve nickel recovery efficiency.

[0005] However, the solid content in nickel oxide ore slurry is generally less than 20% solids because the large electric charge of the ore causes the ores to repel each other and disperse.

[0006] Furthermore, when a nickel oxide ore slurry having a low solid content is used, the nickel concentration in the leachate obtained in the high-pressure acid leaching process is low, making it difficult to efficiently recover nickel.

[0007] Therefore, when attempting to obtain a nickel oxide ore slurry with a high solid content ratio by performing solid-liquid separation of a nickel oxide ore slurry with a low solid content ratio, it is preferable to increase the settling velocity of the solid content in the ore slurry as much as possible, and a method for controlling the settling velocity of the ore slurry is known, for example, as disclosed in Patent Document 1. Patent Document 1 discloses a method for efficiently supplying a nickel oxide ore slurry with a high solid content ratio (Solid%) to a leaching process or the like when recovering valuable metals such as nickel from nickel oxide ore by a hydrometallurgical method, by improving the settling velocity of the ore slurry to shorten the time required for settling and concentration during solid-liquid separation, or by lowering the yield stress of the ore slurry to increase the solid concentration of the ore slurry when it is transported, and specifically, a method for controlling the settling velocity or yield stress of the ore slurry by adding a neutralizing agent to an aqueous slurry of nickel oxide ore and adjusting the pH to the vicinity of the isoelectric point is disclosed.

[0008] However, the method of controlling the pH while continuously measuring the pH of the nickel oxide ore slurry that continuously flows in is not easy and cannot be said to be a suitable method.

[0009] Patent Document 2 discloses a method of increasing the solid content of a nickel oxide ore slurry by using first and second thickeners and adding a flocculant mainly composed of a polymeric hydrocarbon to the first thickener.

[0010] However, the method of increasing the solid content of the nickel oxide ore slurry by adding a flocculant does not allow easy adjustment of the amount of flocculant added, and requires high technical capabilities to increase the solid content to justify the cost of the agent. Furthermore, there are problems such as an increase in the total organic carbon (TOC) concentration in the liquid due to carbon produced by the flocculant, which increases the number of wastewater treatment steps. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2008-189999 A [Patent Document 2] JP 2015-86457 A Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for pretreatment of a nickel oxide ore slurry, which can increase the solid content ratio of the nickel oxide ore slurry without increasing the amount of a flocculant or a chemical for adjusting pH, and to provide a hydrometallurgical process for nickel oxide ore using the nickel oxide ore slurry obtained by the pretreatment method, and a thickener for use in the process. [Means for solving the problem]

[0013] As a result of intensive research conducted by the present inventors in order to solve the above problems, they have discovered that the above problems can be achieved by applying a magnetic force to a nickel oxide ore slurry to effect solid-liquid separation.

[0014] The present invention was completed based on these technical discoveries.

[0015] That is, the first invention according to the present invention is: A pretreatment method for a hydrometallurgical process in which nickel oxide ore slurry, prepared by mixing nickel oxide ore with water or alcohol, is charged into a pressure vessel together with a mineral acid to leach nickel under high pressure, the nickel oxide ore slurry being charged into a thickener before being charged into the pressure vessel to separate the nickel oxide ore slurry into solid and liquid, The method is characterized in that a magnetic force having a magnetic flux density of 0.1 T or more is applied to a nickel oxide ore slurry containing 0.5 mass % or more of a magnetic compound derived from the nickel oxide ore, and the nickel oxide ore slurry is subjected to solid-liquid separation; The second invention is In the method for pretreating a nickel oxide ore slurry according to the first aspect of the present invention, The nickel oxide ore slurry is subjected to solid-liquid separation by applying a magnetic force having a magnetic flux density of 2.0 T or less to the nickel oxide ore slurry, The third invention is In the method for pretreating a nickel oxide ore slurry according to the first or second invention, The thickener is characterized in that a magnet is installed on the bottom side of the thickener body to apply a magnetic force to the nickel oxide ore slurry charged in the thickener, The fourth invention is, In the method for pretreating a nickel oxide ore slurry according to the first or second invention, The thickener is characterized in that a slurry supply pipe and a pump for supplying the nickel oxide ore slurry after solid-liquid separation to the pressurized vessel are connected to a slurry discharge pipe provided on the bottom side of the thickener body, and a magnet is installed near the pump to apply a magnetic force to the nickel oxide ore slurry charged in the thickener.

[0016] Next, the fifth aspect of the present invention is In the hydrometallurgical process of nickel oxide ore, A pretreatment step of mixing nickel oxide ore with water or alcohol to prepare a nickel oxide ore slurry, and charging the resulting slurry into a thickener to separate the slurry into solid and liquid; a leaching step in which the nickel oxide ore slurry after solid-liquid separation is charged into a pressure vessel together with a mineral acid and nickel is leached under high pressure to obtain a leaching slurry consisting of a leachate and a residue; a countercurrent multi-stage washing step in which the leach slurry is introduced into a plurality of continuous thickeners, and the residue is separated and removed while being washed with a washing liquid flowing in a countercurrent to recover the leachate; a neutralization step of adding a neutralizing agent to the recovered leachate, and separating and removing impurity elements contained in the leachate as neutralized precipitate to obtain a neutralized final solution; a sulfurization step of adding a sulfurizing agent to the resulting neutralization final solution to recover nickel in the form of sulfide; A final neutralization process is provided in which a neutralizing agent is added to the nickel-poor solution discharged during the recovery of the sulfide to render it harmless. In the pretreatment step, a magnetic force having a magnetic flux density of 0.1 T or more is applied to a nickel oxide ore slurry containing 0.5 mass % or more of a magnetic compound derived from nickel oxide ore to separate the nickel oxide ore slurry into a solid and liquid state; The sixth invention is In the hydrometallurgical method for producing nickel oxide ore according to the fifth aspect of the present invention, The nickel oxide ore slurry is subjected to solid-liquid separation by applying a magnetic force having a magnetic flux density of 2.0 T or less to the nickel oxide ore slurry.

[0017] Furthermore, the seventh aspect of the present invention is A thickener comprising a thickener body having a cylindrical body and a conical bottom located at a lower part of the body and gradually decreasing in diameter toward a center thereof, the thickener body being used to charge nickel oxide ore slurry prepared by mixing nickel oxide ore with water or alcohol, and separating the nickel oxide ore into a solid-liquid state, The thickener body is provided with a magnet that applies a magnetic force having a magnetic flux density of 0.1 T or more to the nickel oxide ore slurry charged therein, The eighth invention is In the thickener according to the seventh aspect of the present invention, The magnet is disposed on the bottom side of the thickener body, The ninth invention is In the thickener according to the seventh aspect of the present invention, The thickener is characterized by comprising a slurry discharge pipe provided on the bottom side of the thickener body, a slurry supply pipe connected to the slurry discharge pipe for supplying the nickel oxide ore slurry after solid-liquid separation to a pressurized vessel, and a pump, and the magnet is disposed near the pump. Effect of the Invention

[0018] According to the method for pre-treating a nickel oxide ore slurry of the present invention, A magnetic force with a magnetic flux density of 0.1 T or more is applied to the nickel oxide ore slurry, which contains 0.5 mass % or more of magnetic compounds derived from nickel oxide ore, to perform solid-liquid separation. This allows most of the nickel oxide ore in the nickel oxide ore slurry to be attracted and settled to the lower side of the thickener, making it possible to efficiently obtain a nickel oxide ore slurry with a high solid content (solid %).

[0019] In addition, by charging nickel oxide ore slurry with a high solid content (solid%) into the pressure vessel, the amount of nickel passing through per unit time in the high-pressure acid leaching process is increased, which improves the nickel recovery efficiency by the high-pressure acid leaching method and also makes it possible to reduce the amount of chemicals and coagulants used for pH adjustment. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a configuration explanatory diagram of a thickener according to the present embodiment used in the pretreatment method for nickel oxide ore slurry. [Diagram 2] FIG. 2 is a configuration explanatory diagram of an experimental apparatus used in an experiment conducted prior to this embodiment. [Diagram 3] FIG. 1 is a graph showing the relationship between the solid content (Solid%) of the nickel oxide ore slurry and the applied magnetic force in the conventional example and in the experimental examples 1 to 4, in which solid-liquid separation was performed for 24 hours on a nickel oxide ore slurry containing 1.5% by mass of magnetic compounds derived from nickel oxide ore. [Figure 4] FIG. 1 is a graph showing the relationship between the solid content (Solid%) of the nickel oxide ore slurry and the applied magnetic force in the conventional example and in the experimental examples 1 to 4, in which solid-liquid separation was performed for two hours on a nickel oxide ore slurry containing 1.5% by mass of magnetic compounds derived from nickel oxide ore. [Diagram 5]FIG. 11 is a graph showing the relationship between the solid content (Solid%) of the nickel oxide ore slurry and the mass content (mass%) of the magnetic compounds derived from nickel oxide ore contained in the nickel oxide ore slurry according to Experimental Example 2 and Experimental Examples 5 to 10, in which a magnetic force of 0.25 T was applied to the nickel oxide ore slurry and solid-liquid separation was performed for 24 hours. [Figure 6] FIG. 11 is a graph showing the relationship between the solid content (Solid%) of the nickel oxide ore slurry and the mass content (mass%) of the magnetic compounds derived from the nickel oxide ore contained in the nickel oxide ore slurry according to Experimental Example 2 and Experimental Examples 5 to 10, in which a magnetic force of 0.25 T was applied to the nickel oxide ore slurry to perform solid-liquid separation for two hours. [Figure 7] FIG. 2 is a process diagram illustrating a hydrometallurgical method for producing nickel oxide ore according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present invention will be described in detail in the order of [I] a thickener, [II] a method for pretreating a nickel oxide ore slurry, and [III] a method for hydrometallurgy of a nickel oxide ore.

[0022] [I] Thickener First, the thickener according to the present invention will be specifically described, but the thickener according to the present invention is not limited to the structure shown below.

[0023] As shown in Figure 1, the thickener 1 of this embodiment has a thickener body 4 composed of a cylindrical straight body 2 and a conical bottom 3 located at the lower part of the thickener and gradually decreasing in diameter toward the center. Inside the thickener body 4, a rake 5 that rotates at a low speed along the inclined surface of the bottom 3 is arranged, and a magnet 20 is incorporated on the bottom side of the thickener body 4 to apply a magnetic force to the ore slurry charged into the thickener 1.

[0024] In addition, an overflow line 8 through which the supernatant liquid overflows is provided at the top of the straight body section 2, and a cylindrical feedwell 9 is provided concentrically inside the straight body section 2. An ore slurry introduction pipe 10 for introducing an ore slurry with a low solid content (i.e., low-concentration ore slurry) is connected diagonally from above to the upper side of the feedwell 9, and an additive supply pipe 11 with two branched ends is located above the thickener body 4 so that coagulant can be added separately to the ore slurry supply pipe 10 and the feedwell 9.

[0025] Furthermore, a concavely recessed recovery section is provided in the center of the bottom of the thickener body 4, and a slurry extraction pipe 12 extends from the side thereof for extracting the ore slurry with a high solid content (solid %) after solid-liquid separation (i.e., high-concentration ore slurry), and this slurry extraction pipe 12 is connected to a slurry supply pipe 17 and a pump 13 for supplying the high-concentration ore slurry to a pressurized container not shown. In Fig. 1, reference numeral 6 denotes the rotating shaft of the rake 5, reference numeral 7 denotes a drive section, reference numeral 14 denotes an additive flow meter, reference numeral 15 denotes an ore slurry flow meter, and reference numeral 16 denotes an ore slurry specific gravity meter.

[0026] In the thickener 1 having the above structure, the low-concentration nickel oxide ore slurry is mixed with a flocculant in two stages in the additive supply pipe 11 and the feedwell 9, and then introduced into the thickener body 4 from the lower end of the feedwell 9, and separated into a solid-liquid phase part in the upper part and a sedimentation thickening part in the lower part. At that time, the magnetic force of the magnet 20 provided on the bottom side of the thickener body 4 acts on the nickel oxide ore slurry containing magnetic compounds derived from nickel oxide ore, and the nickel oxide ore in the nickel oxide ore slurry is attracted and sedimented, so that the settling speed of the nickel oxide ore is accelerated, and it becomes possible to efficiently obtain a nickel oxide ore slurry (high-concentration ore slurry) with a high solid content (solid%).

[0027] In the thickener 1 shown in FIG. 1, the magnet 20 is disposed on the bottom side of the thickener body 4, but the magnet may be disposed in the vicinity of the pump 13 connected to the slurry discharge pipe 12.

[0028] [II] Method for pretreating nickel oxide ore slurry Next, the method for pre-treating a nickel oxide ore slurry according to the present invention comprises the steps of: The method is characterized in that a nickel oxide ore slurry containing 0.5 mass % or more of magnetic compounds derived from nickel oxide ore is subjected to a magnetic force having a magnetic flux density of 0.1 T or more, thereby subjecting the nickel oxide ore slurry to solid-liquid separation.

[0029] The details will be explained below. 1. Nickel oxide ore slurry and nickel oxide ore The nickel oxide ore slurry used in the present invention is not particularly limited, but examples thereof include nickel oxide ore slurries prepared by mixing nickel oxide ore with water or alcohol, and from the viewpoint of productivity, nickel oxide ore slurries prepared by mixing nickel oxide ore with water are preferred.

[0030] The nickel oxide ore used in the present invention is not particularly limited, and examples thereof include several types such as limonite ore and saprolite ore. These ores may be used alone, or multiple ores may be combined, or metallic nickel or metallic cobalt having the same particle size as the ore may be mixed in addition to the ore. Furthermore, the nickel oxide ore may be subjected to a process of separating the particle size by crushing or sieving with a wet sieve before being dispersed in water.

[0031] 2. Magnetic compounds derived from nickel oxide ores (1) Nickel oxide ore The nickel oxide ore used in the present invention is not particularly limited as described above, but preferably contains 0.3 mass% or more of Ni. The Ni concentration in the nickel oxide ore is preferably measured using an ICP mass spectrometer (Agilent Technologies, Inc. Agilent 7700x ICP-MS), and during analysis, the nickel oxide ore is preferably dissolved in a mixed acid (a mixture of two or more acids), such as aqua regia, to prepare a sample. If the ore components remain undissolved in aqua regia, a small amount of hydrofluoric acid may be added as appropriate.

[0032] (2) Magnetic compounds Examples of the magnetic compounds derived from nickel oxide ore contained in the nickel oxide ore slurry according to the present invention include magnetite (Fe3O4), Ni, Co, and the like.

[0033] The magnetic compound may have any strength of magnetism as long as it has magnetism. The magnetic property refers to ferromagnetism and paramagnetism. Specifically, ferromagnetism refers to a magnetic property that forms spontaneous magnetization, and paramagnetism refers to a property that is magnetized in the same direction as the magnetic field when placed in the magnetic field.

[0034] (3) Percentage of magnetic compounds in nickel oxide ores The proportion of the magnetic compound in the nickel oxide ore is 0.5% by mass or more. When the proportion of the magnetic compound is 0.5% by mass or more, a productive settling rate of the solid matter in the nickel oxide ore slurry can be ensured. The proportion of the magnetic compound is more preferably 1.5% by mass or more, and even more preferably 3.0% by mass or more. In such a range, the settling rate is higher, so the amount of flocculant added can be reduced, and the production efficiency per unit facility area is improved, which is advantageous from an economical point of view.

[0035] (4) Mass ratio of magnetic compounds The mass proportion of magnetic compounds in nickel oxide ore can be analyzed using, for example, MLA (AMICS Mineral Liberation Analysis System) manufactured by Hitachi High-Technologies Corporation.

[0036] (5) A method for adjusting the mass of magnetic compounds in nickel oxide ore The proportion of the magnetic compound in the nickel oxide ore is 0.5% by mass or more as described above. When the proportion of the magnetic compound in the nickel oxide ore is less than 0.5% by mass, the proportion of solids in the nickel oxide ore slurry can be increased by increasing the proportion of the magnetic compound in the nickel oxide ore slurry and performing solid-liquid separation while applying a magnetic force to the nickel oxide ore slurry.

[0037] As a method for increasing the proportion of magnetic compounds, a method for mixing ores containing a large amount of magnetic compounds such as magnetite (Fe3O4) is exemplified. The proportion of magnetic compounds may also be increased by adding iron powder, Ni powder, or Co powder.

[0038] On the other hand, if the mass ratio of the magnetic compound in the nickel oxide ore is too high, even if the nickel oxide ore slurry is subjected to solid-liquid separation while applying a magnetic force, the settling speed does not increase in proportion to the above ratio, and there is a disadvantage that a large amount of sulfuric acid is required in the subsequent smelting process if there is a large amount of magnetite (magnetic compound). Therefore, if the mass ratio of the magnetic compound in the nickel oxide ore exceeds 30 mass%, it is preferable to lower the above ratio by adding ores such as goethite, talc, and chromite.

[0039] 3. Magnetic force acting on nickel oxide ore slurry (1) A device that generates magnetic force (a magnet) The device (magnet) that generates the magnetic force is not particularly limited, but examples thereof include a DC electromagnet and a capacitor-type magnet. The type of magnet may be a permanent magnet or an electromagnet, and examples of the magnet that can be used include a neodymium magnet and a ferrite magnet.

[0040] (2) Magnetic flux density The magnetic flux density of the magnetic force acting on the nickel oxide ore slurry is preferably 0.1 T (tesla) or more. When the magnetic flux density of the magnetic force acting on the nickel oxide ore slurry is 0.1 T or more, a productive settling speed of solid matter in the nickel oxide ore slurry can be ensured. On the other hand, when the magnetic flux density of the magnetic force acting on the nickel oxide ore slurry exceeds 2.0 T, the settling speed of solid matter in the nickel oxide ore slurry remains almost unchanged, and an apparatus with a magnetic flux density exceeding 2.0 T becomes expensive, so that the range of 0.1 T to 2.0 T is preferable.

[0041] The magnetic flux density of the magnetic force acting on the nickel oxide ore slurry is 0.1 T or more as described above, but is preferably 0.25 T or more, and more preferably 0.5 T or more. Within this range, a more productive settling speed of the solid matter in the nickel oxide ore slurry can be ensured.

[0042] (3) Location of the device that generates magnetic force (magnet) The location of the device (magnet) that generates magnetic force is preferably a location where a magnetic force with a magnetic flux density of 0.1 T or more can be applied to the nickel oxide ore slurry charged in the thickener, and is preferably directly below the thickener (i.e., on the bottom side of the thickener) or near the pump connected to the slurry withdrawal pipe provided on the bottom side of the thickener, as described above. The presence of a slurry with a high solid content (Solid%) after solid-liquid separation (i.e., high-concentration ore slurry) near the pump makes it possible to pass a large amount of solids into the pressurized vessel per unit flow rate.

[0043] (4)Method of measuring magnetic force It is preferable to confirm whether the magnetic flux density of the magnetic force acting on the nickel oxide ore slurry is a predetermined value by measuring with a Tesla meter. Using a Tesla meter, it is possible to confirm that a predetermined position has a predetermined magnetic flux density. Although there is no particular limitation on the Tesla meter, it is preferable to use, for example, GV-400 (manufactured by Nippon Denji Measuring Instruments Co., Ltd.) or the like.

[0044] In the following experiment, a Tesla meter was inserted into an empty measuring cylinder with a magnet placed on the bottom side to measure the magnetic flux density inside the measuring cylinder.

[0045] (5) Why does the application of magnetic force increase the sedimentation rate? A magnetic force is applied to the nickel oxide ore slurry, which contains magnetic compounds derived from nickel oxide ore, to separate the nickel oxide ore into solid and liquid. The nickel oxide ore in the nickel oxide ore slurry is attracted to and settles below the thickener, so that the settling speed of the nickel oxide ore slurry can be increased.

[0046] The present inventors speculate that the mechanism by which non-magnetic compounds (non-magnetic compounds) in the nickel oxide ore slurry settle due to magnetic force is that when the magnetic compounds settle, they are aggregated with the non-magnetic compounds, and therefore settle together.

[0047] 4. Flocculant When the nickel oxide ore slurry is subjected to solid-liquid separation, a small amount of a flocculant may be added, and the amount of the flocculant added is 0.030% by mass or less, more preferably 0.015% by mass or less, based on the mass of the ore. In this way, the amount of the flocculant added can be reduced in the present invention, which is very economical.

[0048] The type of flocculant to be added is not particularly limited, and organic flocculants or inorganic flocculants can be used. Specifically, aluminum sulfate, PAC, ferric chloride, anionic polymer flocculants, cationic polymer flocculants, and nonionic polymer flocculants can be preferably used, and a mixture of a plurality of them may be used. In the case of the nickel oxide ore slurry according to the present invention that contains a magnetic compound derived from nickel oxide ore, a polymer flocculant is more preferable as the flocculant to be added.

[0049] After the flocculant is added, the nickel oxide ore slurry is preferably stirred.

[0050] 5. pH adjustment of ore slurry The pH of the nickel oxide ore slurry during solid-liquid separation is not particularly limited, but is preferably in the range of pH 5.0 to pH 9.0, more preferably pH 5.0 to pH 8.0. The reason for controlling the pH within the above range is from the viewpoint of coagulation properties.

[0051] The pH adjuster is not particularly limited, but alkalis such as sodium hydroxide, calcium hydroxide, potassium hydroxide, calcium carbonate, etc., and acids such as sulfuric acid can be suitably used.

[0052] 6. Solids content (Solid%) and its measurement method (1) Solid content (Solid%) The solid content ratio (solid %) of an ore slurry is an index showing the ratio of solids present in an ore slurry that has been left to stand.

[0053] When the solid content in the ore slurry is high, the amount of nickel passing through per unit time in the high-pressure acid leaching process increases, and as described above, the production volume per unit facility increases, making it possible to reduce operating costs and increase nickel recovery efficiency.

[0054] (2) Method for measuring the percentage of solid matter (Solid%) First, water is added to the ore (solid material) to prepare an ore slurry, and a flocculant is added to this ore slurry in an amount of, for example, 0.015% by mass, and the mixture is transferred to a measuring cylinder.

[0055] Next, the measuring cylinder is sealed with a rubber stopper and shaken. After shaking, if it is left to stand for a specified period of time, the ore (solids) in the ore slurry will settle and the ore slurry in the measuring cylinder will separate into a "supernatant portion where no solids are present" (the portion corresponding to the "supernatant liquid phase" in Figure 1) and a "slurry portion where solids are present" (the portion corresponding to the "settling and thickening portion" in Figure 1).

[0056] Therefore, the solid content (Solid%) of the "slurry portion where solids are present" can be expressed by the following (Equation 1) from the (amount of solid matter) and (slurry mass) of the above-mentioned "slurry portion where solids are present".

[0057] Solids content (Solid%) = [(Solid matter amount) / (Slurry mass where solid matter exists)]×100…(Equation 1)

[0058] (3) In the experimental examples below, the “mass percentage of solids in the settled and accumulated portion of the slurry” where solids are present is recorded relative to the “total volume of the slurry” and is expressed as “Solid %.”

[0059] (4) The percentage of solids in the ore slurry during the nickel production process using high-pressure acid leaching can be determined from the mass of water or alcohol added to the slurry relative to the mass of ore (amount of solid matter).

[0060] It is preferable to carry out a calculation so that the solid content in the ore slurry is set, and then to apply the calculation to the nickel production process. In addition, it is preferable to periodically sample the slurry during the production process and adjust the slurry to the specified solid% each time.

[0061] 7. Supernatant liquid and ore slurry after solid-liquid separation (1) Supernatant In the method for pretreating nickel oxide ore slurry according to the present invention, the "supernatant" after solid-liquid separation can be recovered and reused when preparing the ore slurry.

[0062] The "supernatant" recovered in the solid-liquid separation process contains unreacted coagulant, so by reusing it when adjusting the ore slurry, there is no need to prepare new water with coagulant added, which is economical.

[0063] (2) Ore slurry In the method for pretreating nickel oxide ore slurry according to the present invention, the "nickel oxide ore slurry" after solid-liquid separation is mixed with a mineral acid and charged into a pressure vessel.

[0064] After being charged into a pressurized vessel, the nickel is leached under pressure using acid, and a high solids content in the nickel oxide ore slurry is commercially advantageous since it consumes less acid and produces more nickel per unit volume of production equipment.

[0065] The mineral acid used here is not particularly limited, but it is preferable to appropriately select from sulfuric acid, hydrochloric acid, nitric acid, mixed acid, etc., one suited to the production method and subsequent steps.

[0066] [III] Hydrometallurgy of nickel oxide ores. Next, the hydrometallurgical method for producing nickel oxide ore according to the present invention will be described with reference to the process explanatory diagram shown in FIG.

[0067] That is, the hydrometallurgical method for producing nickel oxide ore according to the present invention comprises the steps of: A pretreatment step S1 in which nickel oxide ore slurry prepared by mixing nickel oxide ore with water or alcohol is charged into a thickener and subjected to solid-liquid separation; A leaching step S2 in which the nickel oxide ore slurry after solid-liquid separation is charged into a pressure vessel together with a mineral acid (such as the above-mentioned sulfuric acid), and nickel is acid-leached under high temperature and high pressure, for example, at 220°C to 280°C, to obtain a leached slurry consisting of a leachate and a residue; a countercurrent multi-stage washing step S3 in which the leach slurry is introduced into a plurality of continuous thickeners, and the residue is separated and removed while being washed with a washing liquid flowing in a countercurrent to recover the leachate; A neutralization step S4 in which a neutralizing agent (calcium carbonate, etc.) is added to the recovered leachate, and impurity elements (iron ions) contained in the leachate are separated and removed as neutralized precipitate to obtain a neutralized final solution; A sulfurization step S5 in which a sulfurizing agent (hydrogen sulfide gas or the like) is added to the obtained neutralization final liquid to recover nickel in the form of a sulfide; A final neutralization step S6 is provided in which a neutralizing agent is added to the nickel-poor solution discharged during the recovery of the sulfide to perform a detoxification process. The pretreatment step S1 is characterized in that a magnetic force having a magnetic flux density of 0.1 T or more is applied to a nickel oxide ore slurry containing 0.5 mass % or more of a magnetic compound derived from nickel oxide ore, thereby subjecting the nickel oxide ore slurry to solid-liquid separation.

[0068] According to the hydrometallurgical method for producing nickel oxide ore according to the present invention, In the pretreatment step S1, a nickel oxide ore slurry having a high solid content (solid %) is efficiently obtained, which has the effect of increasing the efficiency of nickel recovery by the high-pressure acid leaching method. EXAMPLES

[0069] First, prior to the examples, the following experiment was carried out using an experimental apparatus shown in FIG. 2, which was equipped with a measuring cylinder 32 for accommodating an ore slurry 31, a table 33 on which the measuring cylinder 32 was placed, and an electromagnet 34 installed on the bottom side of the measuring cylinder 32.

[0070] Nickel oxide ores (limonite ores) A ​​to G were selected as the ores for the ore slurry. (1) Measurement of magnetic force The magnetic flux density of the magnetic force generated by the electromagnet 34 was measured by inserting a Tesla meter [GV-400 (manufactured by Nippon Denji Measuring Instruments Co., Ltd.)] into the empty measuring cylinder 32 .

[0071] (2) Analysis of total mass percent of Fe, Ni, and Co The total mass percentages of Fe, Ni, and Co in the selected nickel oxide ores (limonite ores) A ​​to G were analyzed by dissolving the nickel oxide ores in aqua regia and using an ICP mass spectrometer (Agilent Technologies, Inc., Agilent 7700x ICP-MS).

[0072] (3) Analysis of the mass percentage of magnetic compounds (magnetic substances) The mass percentage of magnetic compounds (substances with magnetic force) in the selected nickel oxide ores (limonite ore) A to G was analyzed using an MLA (AMICS Mineral Liberation Analysis System) manufactured by Hitachi High-Technologies Corporation.

[0073] (4) Measurement of solid content (Solid%) The solid content (solid %) in the nickel oxide ore slurry after 2 hours of solid-liquid separation and 24 hours of solid-liquid separation was measured by the above-mentioned method for measuring the solid content (solid %).

[0074] [experiment] [Experimental Method] Nickel oxide ores (limonite ore) A to G were sieved using a wet sieve with a mesh size of 1.4 mm to adjust the particle size of the ore that was under the sieve. Then, the nickel oxide ore slurries according to the conventional example and experimental examples 1 to 10 shown in Table 1 below were each prepared in an amount of 100 ml by diluting with pure water so that the slurry concentration became 4.0 mass%.

[0075] Next, each nickel oxide ore slurry and flocculant [0.4 mg of PN901 (a nonionic polymer flocculant manufactured by Kurita Water Industries Ltd.) and 0.2 mg of PA904 (anionic polymer flocculant manufactured by Kurita Water Industries Ltd.)] were poured into a measuring cylinder 32 shown in FIG. 2, mixed, and stirred and shaken.

[0076] After sufficient shaking, an electromagnet 34 was set on the bottom side of the measuring cylinder 32, and solid-liquid separation was carried out according to the conditions of the conventional example and experimental examples 1 to 10 shown in Table 1. At this time, the pH of each nickel oxide ore slurry was 7.2.

[0077] Then, the solid content ratio (Solid %) in the nickel oxide ore slurries in the conventional example and experimental examples 1 to 10, which had been subjected to solid-liquid separation for 24 hours and solid-liquid separation for 2 hours, was measured.

[0078] The results are shown in Table 1 and Figures 3 to 6, respectively.

[0079] [Table 1]

[0080] [Experimental Results] (1) When nickel oxide ore A with a "magnetic substance mass" of 1.5% by mass is selected

[0081] (1-1) Conventional example In a conventional example in which solid-liquid separation was performed without applying magnetic force to a nickel oxide ore slurry, the solid% after 24 hours of solid-liquid separation was 23.0%, and the solid% after 2 hours of solid-liquid separation was 21.7%, as shown in Table 1.

[0082] (1-2) Experimental Example 1 In Experimental Example 1, in which solid-liquid separation was performed on a nickel oxide ore slurry by applying a magnetic force with a magnetic flux density of 0.1 T (Tesla), as shown in Table 1, the solid% after 24 hours of solid-liquid separation was 23.8%, and the solid% after 2 hours of solid-liquid separation was 22.8%.

[0083] As a result, it was confirmed that the solid % was improved compared to the conventional example in which solid-liquid separation was performed without the application of magnetic force.

[0084] (1-3) Experimental Examples 2 to 4 In Experiment 2, where a magnetic force of 0.25 T was applied, the solid% after 24 hours of solid-liquid separation was 24.4%, and the solid% after 2 hours of solid-liquid separation was 23.6%. In Experiment 3, where a magnetic force with a magnetic flux density of 0.5 T was applied, the solid% after 24 hours of solid-liquid separation was 25.0%, and the solid% after 2 hours of solid-liquid separation was 24.3%, In Experiment 4, where a magnetic force with a magnetic flux density of 1.0 T was applied, the solid% after 24 hours of solid-liquid separation was 25.2%, the solid% after 2 hours of solid-liquid separation was 24.6%, It was.

[0085] As a result, it was confirmed that increasing the magnetic flux density of the applied magnetic force resulted in a greater improvement in the solid percentage.

[0086] However, from the graphs in Figures 3 and 4, it was confirmed that the improvement effect of Solid% is reduced even if the magnetic flux density of the applied magnetic force is made larger than 0.5 T, so by setting the magnetic flux density to about 0.1 T to 0.5 T, it is possible to increase the improvement effect of Solid% while suppressing the increase in the cost of the device.

[0087] (2) When the magnetic flux density of the applied magnetic force is 0.25T (Tesla)

[0088] (2-1) Experimental Example 2 In Experimental Example 2, in which the "mass of material with magnetic force" was 1.5 mass% (nickel oxide ore A was selected), as described above, the solid% after 24 hours of solid-liquid separation was 24.4%, and the solid% after 2 hours of solid-liquid separation was 23.6%.

[0089] (2-2) Experimental Example 5 In Experimental Example 5, in which the "mass of material with magnetic force" was 1.0 mass% (nickel oxide ore B was selected), the solid% after 24 hours of solid-liquid separation was 23.3%, and the solid% after 2 hours of solid-liquid separation was 21.7%.

[0090] As a result, it was confirmed that the solid percentage of Experimental Example 5 was inferior to that of Experimental Example 2, which contained a larger amount of "magnetic substance mass" at 1.5 mass%.

[0091] (2-3) Experimental Examples 6 to 9 In Experimental Example 6, where the "mass of material with magnetic force" is 3.0 mass% (nickel oxide ore C is selected), the solid% after 24 hours of solid-liquid separation is 25.0%, and the solid% after 2 hours of solid-liquid separation is 24.5%, In Experimental Example 7, where the "mass of material with magnetic force" is 10.0 mass% (nickel oxide ore D is selected), the solid% after 24 hours of solid-liquid separation is 26.1%, and the solid% after 2 hours of solid-liquid separation is 25.8%. In Experimental Example 8, where the "mass of material with magnetic force" is 15.0 mass% (nickel oxide ore E is selected), the solid% after 24 hours of solid-liquid separation is 26.6%, the solid% after 2 hours of solid-liquid separation is 26.4%, In Experimental Example 9, where the "mass of material with magnetic force" is 30.0 mass% (nickel oxide ore F is selected), the solid% after 24 hours of solid-liquid separation is 26.9%, the solid% after 2 hours of solid-liquid separation is 26.7%, It was.

[0092] As a result, it was confirmed that a larger mass percentage of magnetic compounds (magnetic substances) derived from nickel oxide ore resulted in a greater improvement than the solid percentage.

[0093] (2-4) Experimental Example 10 In Experimental Example 10, in which the "mass of material with magnetic force" was 0.5 mass% (nickel oxide ore G was selected), the solid% after 24 hours of solid-liquid separation was 23.1%, and the solid% after 2 hours of solid-liquid separation was 21.7%.

[0094] As a result, the solid% after 2 hours of solid-liquid separation was 21.7%, which was no different from the conventional example, but the solid% after 24 hours of solid-liquid separation was 23.1%, which was an improvement over the conventional example's 23.0%.

[0095] However, from the graphs in Figures 5 and 6, it was confirmed that the effect of improving the Solid% is reduced even if the mass% of the magnetic compounds (magnetic substances) derived from nickel oxide ore is increased to more than 15 mass%, so by setting the mass% of the magnetic compounds (magnetic substances) to approximately 0.5 mass% to 15 mass%, it is possible to increase the effect of improving the Solid% while suppressing the disadvantage of requiring a large amount of sulfuric acid in the smelting process.

[0096] Examples of the present invention will be described below with reference to comparative examples.

[0097] [Comparative Examples, Examples 1 to 10] Nickel oxide ores (limonite ore) A to G selected in the conventional example and experimental examples 1 to 10 were used, and solid-liquid separation of nickel oxide ore slurries according to the comparative example (corresponding to the conventional example) and examples 1 to 10 (corresponding to experimental examples 1 to 10) was carried out under substantially the same conditions (however, not experimental levels but operational levels) as those of the conventional example and experimental examples 1 to 10, using the thickener 1 shown in FIG. 1 in which a magnet 20 was incorporated into the bottom side of the thickener body 4.

[0098] As a result, it was confirmed that the comparative example and examples 1 to 10 also had substantially the same effects as the conventional example and experimental examples 1 to 10 shown in Table 1. [Industrial Applicability]

[0099] According to the method for pretreatment of nickel oxide ore slurry of the present invention, nickel oxide ore slurry having a high solid % can be efficiently obtained, and therefore the method has industrial applicability as a treatment method before charging into a pressure vessel for a high-pressure acid leaching process. [Explanation of symbols]

[0100] 1. Thickener 2 Straight body part 3 bottom 4. Thickener body 5. Rake 6 Rotation Axis 7 Drive unit 8. Overflow Line 9. Feedwell 10 Ore slurry inlet pipe 11 Additive supply pipe 12 Slurry extraction pipe 13. Pump 14 Additive flow meter 15 Ore slurry flow meter 16 Ore slurry specific gravity meter 17 Slurry supply pipe 20. Magnet 31 Ore slurry 32 Measuring cylinder 33 Table 34 Electromagnet S1 Pre-treatment Engineering S2 Leaching Process S3 directional multi-stage cleaning process S4 Neutralization Engineering S5 Vulcanization Engineering S6 Final Neutralization Project

Claims

1. A pretreatment method for a hydrometallurgical process in which nickel oxide ore slurry, prepared by mixing nickel oxide ore with water or alcohol, is charged into a pressure vessel together with a mineral acid to leach nickel under high pressure, the nickel oxide ore slurry being charged into a thickener before being charged into the pressure vessel to separate the nickel oxide ore slurry into solid and liquid, A method for pretreating a nickel oxide ore slurry, comprising applying a magnetic force having a magnetic flux density of 0.1 T or more to a nickel oxide ore slurry containing 0.5 mass % or more of a magnetic compound derived from the nickel oxide ore, thereby subjecting the nickel oxide ore slurry to solid-liquid separation.

2. 2. The method for pretreating a nickel oxide ore slurry according to claim 1, further comprising the step of: subjecting the nickel oxide ore slurry to solid-liquid separation by applying a magnetic force having a magnetic flux density of 2.0 T or less to the nickel oxide ore slurry.

3. 3. The method for pretreating nickel oxide ore slurry according to claim 1, further comprising the step of: disposing a magnet on the bottom side of the thickener body to apply a magnetic force to the nickel oxide ore slurry charged in the thickener.

4. 3. The method for pretreatment of nickel oxide ore slurry according to claim 1, wherein a slurry supply pipe and a pump for supplying the nickel oxide ore slurry after solid-liquid separation to the pressurized vessel are connected to a slurry discharge pipe provided on the bottom side of the thickener body, and a magnet is provided near the pump to apply a magnetic force to the nickel oxide ore slurry charged in the thickener.

5. In the hydrometallurgical process of nickel oxide ore, A pretreatment step of mixing nickel oxide ore with water or alcohol to prepare a nickel oxide ore slurry, and charging the resulting slurry into a thickener to separate the slurry into solid and liquid; a leaching step of charging the nickel oxide ore slurry after solid-liquid separation into a pressure vessel together with a mineral acid and leaching nickel under high pressure to obtain a leaching slurry consisting of a leachate and a residue; a countercurrent multi-stage washing step in which the leach slurry is introduced into a plurality of continuous thickeners, and the residue is separated and removed while being washed with a washing liquid flowing in a countercurrent to recover the leachate; a neutralization step of adding a neutralizing agent to the recovered leachate, and separating and removing impurity elements contained in the leachate as neutralized precipitate to obtain a neutralized final solution; a sulfurization step of adding a sulfurizing agent to the resulting neutralization final solution to recover nickel in the form of sulfide; A final neutralization process is provided in which a neutralizing agent is added to the nickel-poor solution discharged during the recovery of the sulfide to render it harmless. A method for hydrometallurgy of nickel oxide ore, characterized in that in the pretreatment step, a magnetic force having a magnetic flux density of 0.1 T or more is applied to a nickel oxide ore slurry containing 0.5 mass % or more of a magnetic compound derived from nickel oxide ore, thereby separating the nickel oxide ore slurry into solid and liquid.

6. 6. The method for hydrometallurgical smelting of nickel oxide ore according to claim 5, further comprising the step of: applying a magnetic force having a magnetic flux density of 2.0 T or less to the nickel oxide ore slurry to separate the nickel oxide ore slurry into solid and liquid.

7. A thickener comprising a thickener body having a cylindrical body and a conical bottom located at a lower part of the body and gradually decreasing in diameter toward a center thereof, the thickener body being used to charge nickel oxide ore slurry prepared by mixing nickel oxide ore with water or alcohol, and separating the nickel oxide ore into a solid-liquid state, A thickener characterized in that a magnet is provided to apply a magnetic force having a magnetic flux density of 0.1 T or more to the nickel oxide ore slurry charged into the thickener body.

8. 8. The thickener according to claim 7, wherein the magnet is disposed on a bottom surface side of the thickener body.

9. 8. The thickener according to claim 7, further comprising: a slurry discharge pipe provided on the bottom side of the thickener body; a slurry supply pipe connected to the slurry discharge pipe for supplying the nickel oxide ore slurry after solid-liquid separation to a pressure vessel; and a pump, and the magnet is disposed near the pump.

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