Producing method of nickel oxide ore slurry

Abstract

To provide a producing method capable of stably precipitating and concentrating a nickel (Ni) oxide ore slurry without increasing a used amount of a coagulant.SOLUTION: In a producing method of a Ni oxide ore slurry characterized in that a method for producing a Ni oxide ore slurry used as a raw material for a hydrometallurgical method of Ni by a high-pressure acid leaching method comprises: a pulverization / classification process for aligning the Ni oxide ore to a predetermined particle size; a slurry process for preparing a Ni oxide ore slurry by mixing water with the obtained Ni oxide ore particles; a Ni oxide ore slurry concentration process in which the obtained Ni oxide ore slurry is separated into solid-liquid to precipitate and concentrate the Ni oxide ore slurry, the zeta potential of the Ni oxide ore in the Ni oxide ore slurry to be separated into solid-liquid is adjusted within the range of ±30 mV to precipitate and concentrate the Ni oxide ore slurry.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a nickel oxide ore slurry used as a raw material in a nickel hydrometallurgy process using a high-pressure acid leaching method, and more particularly to a method for producing a nickel oxide ore slurry that enables stable sedimentation and concentration treatment of the nickel oxide ore slurry without increasing the amount of a flocculant used. [Background technology]

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

[0003] This ore slurry is often made by blending several types of nickel oxide ores so that the amount of acid consumed 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 ore slurry, a higher (or larger) weight percentage of solids (ore solids) in the ore slurry constituting the ore slurry (hereinafter referred to as "Solid %") increases the amount of nickel passing through per unit time in the high-pressure acid leaching process, and accordingly, more compact equipment is required, which reduces investment and operating costs and increases nickel recovery efficiency, making this preferable.

[0005] When attempting to obtain a high solid% by performing solid-liquid separation from such an ore slurry (i.e., subjecting the ore slurry to a settling and thickening treatment), it is preferable that the settling velocity of the solids in the ore slurry is as high as possible (also referred to as "fast"). As a method for controlling the settling velocity of the ore slurry, for example, a method disclosed in Patent Document 1 is known.

[0006] Patent Document 1 discloses a method for pretreating nickel oxide ore in which the settling rate of the ore slurry is increased to shorten the time required for settling and concentration during solid-liquid separation, or the yield stress of the ore slurry is reduced to increase the solid concentration of the ore slurry when it is transported, in order to efficiently supply an ore slurry with a high solid concentration (solid %) to a leaching process or the like when recovering valuable metals such as nickel from nickel oxide ore by a hydrometallurgical method. Specifically, the patent document discloses a method for controlling the settling rate 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 near the isoelectric point.

[0007] Furthermore, Patent Document 2 discloses an equipment and method for producing an ore slurry in which a plurality of thickeners (first and second thickeners) are used to increase the solids percentage of the ore slurry.

[0008] That is, Patent Document 2 discloses an ore slurry production facility including a first thickener for preconcentrating raw ore slurry to obtain intermediate ore slurry, and a second thickener for concentrating the intermediate ore slurry to obtain concentrated ore slurry, which has a higher thickening effect (settling and thickening in a thickener) than the first thickener. It also discloses a method for producing an ore slurry in which the raw ore slurry is preconcentrated by the first thickener to obtain intermediate ore slurry, and the intermediate ore slurry is concentrated by the second thickener, which has a higher thickening effect than the first thickener. According to the ore slurry production facility and method disclosed in Patent Document 2, the intermediate ore slurry preconcentrated by the first thickener is supplied to the second thickener, so that the settling speed of the ore slurry is increased in the second thickener, and it is possible to increase the slurry processing amount. Furthermore, since the latter thickener is composed of the second thickener with a high thickening effect, it is possible to produce concentrated ore slurry with a high solid content rate (Solid%) and specific gravity. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2008-189999 A [Patent Document 2] JP 2015-086457 A Summary of the Invention [Problem to be solved by the invention]

[0010] Incidentally, in the thickening (hereinafter referred to as "sedimentation thickening") treatment of the ore slurry disclosed in Patent Documents 1 and 2, a flocculant containing high molecular weight hydrocarbons as a main component is used. The flocculant can increase the settling velocity by increasing the amount added, but on the other hand, the ore density in the flocculant is likely to decrease due to the increase in the proportion of high molecular weight hydrocarbons contained in the flocculant itself. In this case, it becomes difficult to increase the solid% of the ore slurry. For this reason, excessive addition of flocculant with a focus only on increasing the settling velocity increases the cost of the chemicals and increases the viscosity of the ore slurry, which increases the load on the equipment. There is also a problem that the total organic carbon (TOC) concentration in the liquid increases, making wastewater treatment difficult.

[0011] Furthermore, in the sedimentation concentration treatment of the ore slurry, the behavior of sedimentation concentration differs depending on the type of ore, so the treatment conditions (e.g., the type and amount of flocculant used) need to be adjusted depending on the type and mixing ratio of the ore, the shape of the thickener, etc. If the treatment conditions are not properly adjusted, it becomes difficult to settle the ore (i.e., separate the solid and liquid) even if a large amount of flocculant is added, and there is a problem that the sedimentation concentration treatment of the nickel oxide ore slurry cannot be stably performed.

[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 producing a nickel oxide ore slurry, which enables stable sedimentation and thickening treatment of a nickel oxide ore slurry without increasing the amount of flocculant used, even when the type and mixing ratio of the ores, the shape of the thickener, etc. are changed. [Means for solving the problem]

[0013] As a result of intensive research by the present inventors to solve the above problems, it has been found that the problems can be achieved by adjusting the zeta potential of the nickel oxide ore in the nickel oxide ore slurry to be subjected to solid-liquid separation to within the range of ±30 mV.

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

[0015] That is, the first invention according to the present invention is: A method for producing nickel oxide ore slurry used as a raw material in a nickel hydrometallurgy process using a high pressure acid leaching method, comprising the steps of: A crushing and classification process for aligning the nickel oxide ore to a specified particle size; a slurrying step of mixing water with the nickel oxide ore particles obtained in the crushing and classification step to prepare a nickel oxide ore slurry; a nickel oxide ore slurry concentration step of subjecting the nickel oxide ore slurry obtained in the slurrying step to solid-liquid separation to settle and concentrate the nickel oxide ore slurry; 1. A method for producing a nickel oxide ore slurry comprising: The method is characterized in that the zeta potential of the nickel oxide ore in the nickel oxide ore slurry to be separated into solid and liquid is adjusted to within a range of ±30 mV, and the nickel oxide ore slurry is concentrated by sedimentation.

[0016] The second aspect of the present invention is In the method for producing a nickel oxide ore slurry according to the first aspect of the present invention, The nickel oxide ore slurry is characterized in that the zeta potential of the nickel oxide ore in the nickel oxide ore slurry is adjusted to within a range of ±30 mV by blending positively charged nickel oxide ore particles and negatively charged nickel oxide ore particles, respectively; The third invention is In the method for producing a nickel oxide ore slurry according to the second aspect of the present invention, The present invention is characterized in that one of the positively charged nickel oxide ore particles and the negatively charged nickel oxide ore particles is made of nickel oxide ore particles having a particle size of 1.4 mm or more, and the other is made of nickel oxide ore particles having a particle size of less than 1.4 mm.

[0017] Furthermore, the fourth aspect of the present invention is In the method for producing a nickel oxide ore slurry according to the first aspect of the present invention, The method is characterized in that the pH of the nickel oxide ore slurry to be separated into solid and liquid is adjusted to adjust the zeta potential of the nickel oxide ore in the nickel oxide ore slurry to within a range of ±30 mV; The fifth invention is In the method for producing a nickel oxide ore slurry according to the fourth aspect of the present invention, The method is characterized in that water to which an alkali or an acid has been added is mixed with the nickel oxide ore particles in the slurrying step to adjust the pH of the nickel oxide ore slurry to be separated into solid and liquid. Effect of the Invention

[0018] According to the method for producing a nickel oxide ore slurry of the present invention, The zeta potential (positive and negative charge) of the nickel oxide ore in the nickel oxide ore slurry to be separated into solid and liquid is adjusted to within the range of ±30 mV, which reduces the repulsion between the nickel oxide ores and makes it easier for the nickel oxide ores to become denser. This has the effect of enabling stable sedimentation and concentration treatment of the nickel oxide ore slurry without increasing the amount of coagulant used. [Brief description of the drawings]

[0019] [Figure 1] A graph showing the relationship between the blend ratio of oxide III and oxide IV and the zeta potential [mV]. [Diagram 2] A graph showing the relationship between the blend ratio of oxide ore I and oxide ore II and the zeta potential [mV]. [Diagram 3] A graph showing the relationship between the pH and zeta potential [mV] of the ore slurry for oxide ore V. [Figure 4] FIG. 2 is a process diagram illustrating a method for producing a nickel oxide ore slurry according to the present embodiment and a method for hydrometallurgy of nickel by a high-pressure acid leaching method using the produced nickel oxide ore slurry as a raw material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail.

[0021] FIG. 4 is a process explanatory diagram showing the method for producing nickel oxide ore slurry according to the present embodiment, and the method for hydrometallurgy of nickel by high-pressure acid leaching using the produced nickel oxide ore slurry as a raw material.

[0022] 1. Method for producing nickel oxide ore slurry The manufacturing process S1 of the nickel oxide ore slurry according to this embodiment is as follows: The nickel oxide ore is crushed and classified to a specified particle size. a slurrying step of mixing water with the nickel oxide ore particles obtained in the crushing and classification step to prepare a nickel oxide ore slurry; a nickel oxide ore slurry concentration step of subjecting the nickel oxide ore slurry obtained in the slurrying step to solid-liquid separation to settle and concentrate the nickel oxide ore slurry; has.

[0023] (1) Grinding and classification process In the crushing and classification process, the raw material nickel oxide ore is crushed using a crusher or disintegrator, and the crushed ore is sieved to classify it at a specified classification point, and the ore particles that exceed the size are removed to obtain only the undersized ore.

[0024] Meanwhile, as nickel oxide ore used as a raw material for the nickel hydrometallurgy method using the high pressure acid leaching method, limonite, which has a low magnesium content and is inexpensive, and consumes excessive sulfuric acid, is mainly used. In general, limonite has a low Ni content of about 0.8% by weight to 1.5% by weight, so that the Ni content or at least one selected from the content of elements other than Ni, Co, Mg, Cr, Fe, Mn, Al, and Si, is a predetermined content, or a ratio of a specific element to a specific element to be recovered, such as Ni, other than Ni, satisfies a predetermined value, is blended with a plurality of ore types. For example, limonite is mainly used, and saprolite, which has a higher magnesium content than limonite but a nickel content about twice as high as limonite, is often mixed and used to satisfy the above conditions of the Ni content and the content of elements other than Ni.

[0025] The nickel oxide ore raw material, which is a blend of multiple ore types, is then gradually pulverized, preferably using a multiple-stage crusher or classifier, so that the ore particles have a predetermined particle size.

[0026] Among these multi-stage classifiers, at least the final stage may use a wet sieve such as a vibrating screen or a trommel, and nickel oxide ore is charged into the classifier together with water and sieved.

[0027] In addition, when the above-mentioned wet sieve is used in the final stage, the ore that falls through the sieve is recovered in the form of a "dilute ore slurry" described below, so this crushing and classification process essentially includes the slurrying process described below. Therefore, in such a case, it is not necessary to provide a slurrying process separately from the crushing and classification process.

[0028] (2) Slurrying process In the slurrying process, the ore particles obtained in the crushing and classification process are mixed with water to prepare a nickel oxide ore slurry. The resulting nickel oxide ore slurry is the ore slurry before the concentration process, and is also called "dilute ore slurry" to distinguish it from the concentrated ore slurry that is subjected to the leaching process of the above-mentioned hydrometallurgical method. The nickel oxide ore slurry processed in the concentration process is also called "concentrated ore slurry".

[0029] The water to be mixed with the ore particles may be, for example, industrial water, or process water discharged from a hydrometallurgical method for producing nickel oxide ore.

[0030] (3) Concentration process In the concentration process, the "dilute ore slurry (nickel oxide ore slurry)" obtained in the slurrying process is subjected to solid-liquid separation, and the "dilute ore slurry" is concentrated by settling to obtain an ore slurry with a high solid% (i.e., concentrated ore slurry).

[0031] The method for producing a nickel oxide ore slurry according to the present invention is characterized in that the zeta potential of the nickel oxide ore in the "dilute ore slurry (nickel oxide ore slurry)" to be subjected to solid-liquid separation is adjusted to within a range of ±30 mV, thereby subjecting the "dilute ore slurry" to a sedimentation concentration treatment while avoiding the use of a flocculant which is difficult to handle or while significantly reducing the amount of flocculant used.

[0032] Here, zeta potential refers to the electric potential of the liquid surface (sliding surface) that moves along with the surface of particles dispersed in the liquid. The surfaces of particles dispersed in the liquid are usually positively or negatively charged, but since it is difficult to directly measure the surface potential of a particle, zeta potential is used as an electric potential that has properties that substitute for the surface potential. Particles with positive and positive zeta potentials repel each other, and similarly, particles with negative and negative zeta potentials repel each other. On the other hand, particles with positive and negative zeta potentials tend to stick to each other (i.e., they tend to aggregate).

[0033] The method for adjusting the zeta potential of the nickel oxide ore in the "dilute ore slurry (nickel oxide ore slurry)" to within the range of ±30 mV is as follows: (3-1) A method of forming a nickel oxide ore in a nickel oxide ore slurry by blending "positively charged nickel oxide ore particles" and "negatively charged nickel oxide ore particles"; (3-2) A method in which one of the "positively charged nickel oxide ore particles" and the "negatively charged nickel oxide ore particles" is composed of particles having a particle diameter of 1.4 mm or more, and the other is composed of particles having a particle diameter of less than 1.4 mm; (3-3) A method of adjusting the pH of the "dilute ore slurry (nickel oxide ore slurry)" to be subjected to solid-liquid separation so that the zeta potential is set within the range of ±30 mV; etc. are examples. The following explains.

[0034] 2. A method for adjusting the zeta potential of the nickel oxide ore to within the range of ±30mV (1) Method using "positively charged nickel oxide ore particles" and "negatively charged nickel oxide ore particles" (1-1) A method of adjusting the zeta potential by blending "positively charged nickel oxide ore particles" that are positively charged in a nickel oxide ore slurry, and "negatively charged nickel oxide ore particles" that are negatively charged in a nickel oxide ore slurry.

[0035] (1-2) An example of a "positively charged nickel oxide ore" is a nickel oxide ore composed mainly of goethite [FeO(OH)] and containing almost no silicon dioxide (SiO2).

[0036] Goethite is easily positively charged, while silicon dioxide is easily negatively charged. Moreover, it has been confirmed that the effect of silicon dioxide in charging negatively is greater than the effect of goethite in charging positively. For example, even if a nickel oxide ore contains about 50% goethite, if it also contains about 8% to 10% or more silicon dioxide, it has been confirmed that the nickel oxide ore as a whole will be negatively charged.

[0037] (1-3) Thus, an example of a "positively charged nickel oxide ore" is a nickel oxide ore having the above composition that contains almost no silicon dioxide, and an example of a "negatively charged nickel oxide ore" is a nickel oxide ore that contains a relatively large amount of silicon dioxide.

[0038] (1-4) However, if the ore is sorted into "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" based on its composition (e.g., the content of silicon dioxide), it is not possible to manage whether the ore is "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" for each mining area, because the composition of the ore differs depending on the mining area.

[0039] However, if the zeta potential of mined ores is measured for each place of origin and sorted into "positively charged nickel oxide ore" or "negatively charged nickel oxide ore", it is possible to manage whether the ore is "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" for each place of origin, since sorting is based on the measured zeta potential.

[0040] (2) Method using nickel oxide ore particles with a diameter of 1.4 mm or more and nickel oxide ore particles with a diameter of less than 1.4 mm (2-1) A method of adjusting the zeta potential by blending nickel oxide ore particles having a particle size of 1.4 mm or more with nickel oxide ore particles having a particle size of less than 1.4 mm.

[0041] (2-2) When the ore is sorted into "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" based on the above-mentioned composition (silicon dioxide content, etc.), the composition of the ore after crushing is not necessarily uniform even if the ore is mined from the same production area. In other words, there are cases where the composition of the ore after crushing differs depending on the crushed particle size.

[0042] In such a case, if the zeta potential of the crushed ore is measured for each particle size and sorted into "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" according to the particle size, it is possible to manage whether the ore is "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" according to the particle size because the sorting is based on the measured zeta potential.

[0043] For example, Table 1 shows the results of measuring the zeta potential using ultrasonic waves while stirring nickel oxide ore that was crushed and sieved from a certain production area into oxide ore I with a particle size (D50) of 1.4 mm or more, and oxide ore II with a particle size (D50) of less than 1.4 mm. Water was added to each of these to create a slurry with a concentration of 4% by weight.

[0044] [Table 1]

[0045] Referring to Table 1, it can be seen that the zeta potential of oxide ore I, which has a particle size (D50) of 1.4 mm or more, is negative (-33 mV), and shows a zeta potential with properties that are clearly different from those of oxide ore II. This is due to the fact that the silicon dioxide content in oxide ore I is greater than that in oxide ore II, and supports the idea that it is possible to classify crushed ores into "positively charged nickel oxide ore" or "negatively charged nickel oxide ore" depending on their particle size.

[0046] Incidentally, the zeta potentials of oxide ore I and oxide ore II in each ore slurry are -33mV and 127mV, respectively, which are outside the range of ±30mV. Therefore, even if a large amount of coagulant is added to each ore slurry, the solid% of the ore slurry is not increased, and the ores are difficult to settle (solid-liquid separation). It has also been confirmed that the supernatant liquid of each ore slurry is suspended by the remaining fine ores.

[0047] In addition, ore having a particle size (D50) of 1.4 mm or more may be referred to as "Over Size" ore in this specification, and the upper limit of "Over Size" is 4.0 mm.

[0048] (3) Method for adjusting the pH of dilute ore slurry (nickel oxide ore slurry) (3-1) A method of adjusting the pH of the nickel oxide ore slurry to near the isoelectric point so that the zeta potential is set within the range of ±30 mV.

[0049] (3-2) The zeta potential is greatly affected by the pH of the dispersion medium. Therefore, by adjusting the pH to near the isoelectric point, the repulsion between ore particles can be suppressed and the coagulation properties can be improved.

[0050] As an agent for adjusting the pH, for example, sodium hydroxide can be used. The pH can be adjusted by directly adding an agent to the nickel oxide ore slurry, or by preparing an aqueous solution (e.g., an alkaline aqueous solution) whose pH has been adjusted in advance and using the aqueous solution instead of the water to be mixed with the nickel oxide ore particles in the slurrying step. When an aqueous solution whose pH has been adjusted in advance is used, the pH of the nickel oxide ore slurry can be more easily made uniform than when an agent is directly added to the nickel oxide ore slurry.

[0051] It is needless to say that the above-mentioned method of using the "positively charged nickel oxide ore particles" and the "negatively charged nickel oxide ore particles", or the method of using the "oversized nickel oxide ore particles" and the "nickel oxide ore particles having a particle size of less than 1.4 mm", and the above-mentioned method of adjusting the pH of the nickel oxide ore slurry may be used in combination.

[0052] (3-3) Incidentally, the above method (3) for adjusting the pH of the nickel oxide ore slurry is somewhat similar in structure to the method described in Patent Document 1 in which a neutralizing agent is added to an aqueous slurry of nickel oxide ore to adjust the pH to near the isoelectric point and control the settling rate of the ore slurry.

[0053] However, Patent Document 1 does not describe conditions for adjusting the zeta potential of the nickel oxide ore in the nickel oxide ore slurry to be separated into solid and liquid within the range of ±30 mV, or a method for concentrating the nickel oxide ore slurry by sedimentation under the above conditions while avoiding the use of a flocculant that is difficult to handle or while significantly reducing the amount of flocculant used. Therefore, the method of the present invention has a different configuration from the method described in Patent Document 1.

[0054] 3. High pressure acid leaching for hydrometallurgy of nickel As shown in FIG. 4, a hydrometallurgical process by a high-pressure acid leaching method using the nickel oxide ore slurry (concentrated ore slurry) obtained by the nickel oxide ore slurry producing method according to the present embodiment as a raw material includes the following steps: The nickel oxide ore slurry production step S1; A leaching step S2 in which a mineral acid is added to the concentrated ore slurry obtained in the manufacturing step S1 and nickel is leached by performing an acid leaching treatment under high temperature and high pressure; a countercurrent multi-stage washing step S3 in which the leachate slurry consisting of the leachate and residue produced in the leachate step S2 is introduced into a plurality of continuous thickeners (precipitation and concentration devices) and the residue is separated and removed while being washed with a washing solution flowing in a countercurrent to recover the leachate; a neutralization step S4 in which a neutralizing agent is added to the recovered leachate, and impurity elements 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 such as hydrogen sulfide is added to the neutralization end liquid to recover nickel in the form of sulfide; A final neutralization step S6 in which a neutralizing agent such as slaked lime is added to the nickel-poor solution discharged during the recovery of the sulfide to make it harmless; It generally consists of

[0055] 4. Improvement effect of the method of the present invention According to the method of the present invention, the zeta potential (positive and negative electric charge) of the nickel oxide ore in the nickel oxide ore slurry to be separated into solid and liquid is adjusted to within the range of ±30 mV, thereby reducing the repulsion between the nickel oxide ores and making it easier for the nickel oxide ores to become denser. This has an improved effect of making it possible to avoid the use of a flocculant which is difficult to handle, or to stably carry out the sedimentation concentration treatment of the nickel oxide ore slurry while significantly reducing the amount of flocculant used. EXAMPLES

[0056] Examples of the present invention will now be described in detail.

[0057] [Example 1] Nickel oxide ore was crushed to prepare two nickel oxide ores with different zeta potentials [positively charged nickel oxide ore III indicated by the symbol ◆ in Table 2 and Figure 1, and negatively charged nickel oxide ore IV indicated by the symbol ● in Figure 1], and the mixture of the above-mentioned ore oxide III and ore oxide IV was adjusted to obtain the blending conditions shown in Table 3 and Figure 1 [i.e., positively charged nickel oxide ore III indicated by the symbol ◆ in Figure 1 with a blend (mixture) ratio of ore III and ore IV of "10:0", blend (1) indicated by the symbol □ with a blend ratio of ore III and ore IV of "8:2", blend (2) indicated by the symbol △ with a blend ratio of ore III and ore IV of "7:3", and negatively charged nickel oxide IV indicated by the symbol ● with a blend ratio of ore III and ore IV of "0:10".

[0058] Next, the slurry was diluted with pure water to a concentration of 4% by weight to prepare four types of ore slurries [positively charged nickel oxide ore III, blend (1), blend (2), negatively charged nickel oxide ore IV], and the zeta potential of each ore in each ore slurry [positively charged nickel oxide ore III, blend (1), blend (2), negatively charged nickel oxide ore IV] was measured by ultrasonic measurement while stirring. The results are shown in Table 3.

[0059] Then, the slurries of each ore [positively charged nickel oxide ore III, blend (1), blend (2), and negatively charged nickel oxide ore IV] were subjected to solid-liquid separation (sedimentation concentration).

[0060] At this time, the ore slurry separated into solid and liquid, and the weight percentage of the solids in the piled up portion formed by the settling of the solids after 2 hours was recorded to calculate the solid% [%].

[0061] The results are also shown in Table 3.

[0062] [Table 2]

[0063] [Table 3]

[0064] [evaluation] (1) In the case of the zeta potential of the nickel oxide ore in the ore slurry to be subjected to solid-liquid separation (sedimentation concentration) being outside the range of ±30 mV [positively charged nickel oxide ore III and negatively charged nickel oxide ore IV], as shown in Table 3, it is confirmed that the "positively charged nickel oxide ore III" and "negatively charged nickel oxide ore IV" do not settle (solid-liquid separation) within the specified time, and the supernatant liquid in each ore slurry is suspended by the remaining "positively charged nickel oxide ore III" and "negatively charged nickel oxide ore IV".

[0065] In actual operation, the time available for the sedimentation thickening process is limited because it is necessary to efficiently perform the leaching process of the ore slurry. If sedimentation cannot be completed within the specified time, the supernatant liquid after the sedimentation thickening process is suspended due to the fine ores remaining in the liquid as described above, and is removed outside the system and lost.

[0066] (2) On the other hand, when "positively charged nickel oxide ore III" and "negatively charged nickel oxide ore IV" are blended so that the zeta potential of the nickel oxide ore in the ore slurry is set within the range of ±30 mV [Blend (1) is "8:2" and Blend (2) is "7:3"], the suspension state of the ore slurry is improved (no suspension) as shown in Table 3, and solid-liquid separation (sedimentation concentration) is possible.

[0067] (3) In addition, when "positively charged nickel oxide ore III" and "negatively charged nickel oxide ore IV" are mixed (blended) so that the absolute value of the zeta potential becomes smaller, the solid percentage is further improved [from "15.5%" for blend (2) with a zeta potential of "-21 mV" to "17.6%" for blend (1) with a zeta potential of "16 mV"].

[0068] (4) Furthermore, no flocculant or the like was added in Example 1. This result suggests that even when a flocculant is added to improve the settling rate, the amount of flocculant added itself may be significantly reduced.

[0069] [Example 2] After crushing, the nickel oxide ore was sieved and separated into oxide I with a particle size (D50) of 1.4 mm or more and oxide II with a particle size (D50) of less than 1.4 mm [oxide I shown by the symbol ◆ in Table 1 and Figure 2 and oxide II shown by the symbol ● in Figure 2], and the mixture of oxide I and oxide II was adjusted to obtain the blending conditions shown in Table 4 and Figure 2 [i.e., oxide I shown by the symbol ◆ in Figure 2 with a blend ratio of oxide I and oxide II of "10:0", blend (3) shown by the symbol □ with a blend ratio of oxide I and oxide II of "2:8", and oxide II shown by the symbol ● with a blend ratio of oxide I and oxide II of "0:10"].

[0070] Next, the three ores [nickel oxide ore I, blend (3), and nickel oxide ore II] were diluted with pure water to a slurry concentration of 4% by weight, and the zeta potential of each ore [nickel oxide ore I, blend (3), and nickel oxide ore II] in each ore slurry was measured by ultrasonic measurement while stirring. The results are shown in Table 4.

[0071] Then, the slurries of each ore [nickel oxide ore I, blend (3), and nickel oxide ore II] were subjected to solid-liquid separation (sedimentation concentration).

[0072] At this time, the ore slurry separated into solid and liquid, and the weight percentage of the solids in the piled up portion formed by the settling of the solids after 2 hours was recorded to calculate the solid% [%].

[0073] The results are also shown in Table 4.

[0074] [Table 4]

[0075] [evaluation] (1) In the case of the nickel oxide ore [nickel oxide ore I and nickel oxide ore II] slurries in which the zeta potential of the nickel oxide ore in the ore slurry to be subjected to solid-liquid separation (sedimentation and concentration) is outside the range of ±30 mV, as shown in Table 4, it is confirmed that "nickel oxide ore I" and "nickel oxide ore II" do not settle (solid-liquid separation), and the supernatant liquid in each ore slurry is suspended by the remaining "nickel oxide ore I" and "nickel oxide ore II".

[0076] (2) On the other hand, when "nickel oxide ore I" and "nickel oxide ore II" are blended so that the zeta potential of the nickel oxide ore in the ore slurry is set within the range of ±30 mV [blend (3) is "2:8"], the suspension state of the ore slurry is improved (no suspension) as shown in Table 4, and solid-liquid separation (sedimentation concentration) is possible.

[0077] (3) Furthermore, no flocculant or the like was added in Example 2. This result suggests that even when a flocculant is added to improve the settling rate, the amount of flocculant added itself may be significantly reduced.

[0078] [Example 3] Nickel oxide ore was crushed to prepare oxide ore V, which was then divided into two groups and diluted with pure water so that the slurry concentration of each group was 4% by weight to prepare two sets of ore slurries.

[0079] Then, 1 mol / L sodium hydroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to one of the ore slurries to adjust the pH of the ore slurry to near the isoelectric point, and no sodium hydroxide was added to the other ore slurry.

[0080] Next, the zeta potential of the ore [nickel oxide ore V] in each ore slurry was measured using ultrasound while stirring.The zeta potential of the ore in the ore slurry indicated by the symbol ◆ in Table 5 and Figure 3 (pH adjustment: indicated as "before") was 71.8 mV, and the zeta potential of the ore in the ore slurry indicated by the symbol □ in Figure 3 (pH adjustment: indicated as "after") was -2.4 mV.

[0081] Then, the ore slurry (pH adjustment: indicated as "before") and the ore slurry (pH adjustment: indicated as "after") were each subjected to solid-liquid separation (sedimentation thickening).

[0082] At this time, the ore slurry separated into solid and liquid, and the weight percentage of the solids in the piled up portion formed by the settling of the solids after 2 hours was recorded to calculate the solid% [%].

[0083] The results are also shown in Table 5.

[0084] [Table 5]

[0085] [evaluation] (1) In the ore slurry (pH adjustment: indicated as “before”) in which the zeta potential of the nickel oxide ore in the ore slurry to be subjected to solid-liquid separation (sedimentation and concentration) is outside the range of ±30 mV, it is confirmed that “oxide ore V” does not settle (solid-liquid separation) as shown in Table 5, and the supernatant liquid in the ore slurry is suspended by the remaining “oxide ore V”.

[0086] (2) On the other hand, in the ore slurry in which the pH has been adjusted so that the zeta potential of the nickel oxide ore in the ore slurry is set within the range of ±30 mV (pH adjustment: indicated as “after”), it has been confirmed that the suspension state of the ore slurry is improved (no suspension) as shown in Table 5, and solid-liquid separation (sedimentation concentration) is possible.

[0087] (3) Furthermore, no flocculant or the like was added in Example 3. This result suggests that even when a flocculant is added to improve the settling rate, the amount of flocculant added itself may be significantly reduced. [Industrial Applicability]

[0088] According to the method for producing a nickel oxide ore slurry of the present invention, Since the nickel oxide ore slurry can be stably concentrated by sedimentation without increasing the amount of flocculant used, the produced nickel oxide ore slurry has industrial applicability as a raw material for a nickel hydrometallurgy process using a high-pressure acid leaching method. [Explanation of symbols]

[0089] S1 Nickel oxide ore slurry manufacturing process S2 leaching process S3 Countercurrent multi-stage cleaning process S4 Neutralization process S5 Sulfurization process S6 Final neutralization step

Claims

1. A method for producing nickel oxide ore slurry used as a raw material in a nickel hydrometallurgy process using a high pressure acid leaching method, comprising the steps of: a crushing and classification step of aligning the nickel oxide ore to a predetermined particle size; a slurrying step of mixing water with the nickel oxide ore particles obtained in the crushing and classification step to prepare a nickel oxide ore slurry; a nickel oxide ore slurry concentration step of subjecting the nickel oxide ore slurry obtained in the slurrying step to solid-liquid separation to settle and concentrate the nickel oxide ore slurry; 1. A method for producing a nickel oxide ore slurry comprising: A method for producing a nickel oxide ore slurry, comprising adjusting the zeta potential of the nickel oxide ore in the nickel oxide ore slurry to be subjected to solid-liquid separation to within a range of ±30 mV, and concentrating the nickel oxide ore slurry by sedimentation.

2. 2. The method for producing a nickel oxide ore slurry according to claim 1, further comprising blending positively charged nickel oxide ore particles and negatively charged nickel oxide ore particles to adjust the zeta potential of the nickel oxide ore in the nickel oxide ore slurry to within a range of ±30 mV.

3. 3. The method for producing a nickel oxide ore slurry according to claim 2, wherein one of the positively charged nickel oxide ore particles and the negatively charged nickel oxide ore particles is composed of nickel oxide ore particles having a particle size of 1.4 mm or more, and the other is composed of nickel oxide ore particles having a particle size of less than 1.4 mm.

4. 2. The method for producing a nickel oxide ore slurry according to claim 1, further comprising adjusting a pH of the nickel oxide ore slurry to be subjected to solid-liquid separation so as to adjust a zeta potential of the nickel oxide ore in the nickel oxide ore slurry to within a range of ±30 mV.

5. 5. The method for producing nickel oxide ore slurry according to claim 4, further comprising mixing water to which an alkali or an acid has been added with the nickel oxide ore particles in the slurrying step to adjust the pH of the nickel oxide ore slurry to be subjected to solid-liquid separation.

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