JP2019077928A - Neutralization treatment method and wet refining method of nickel oxide ore - Google Patents

Abstract

To provide a neutralization treatment method capable of reducing used amount of a neutralization agent during a neutralization process for neutralizing an exudate in a wet refining method of a nickel oxide ore, and the wet refining method of the nickel oxide ore.SOLUTION: There is provided a neutralization treatment method including: conducting an exudation treatment by acid on a nickel oxide ore to obtain an exudation slurry containing an exudate containing nickel and an exudation residue, then adding a neutralization agent to the exudate obtained by a solid liquid separation treatment on the exudation slurry and conducting a neutralization treatment to obtain a neutralized final liquid containing nickel and a neutralization deposit containing impurity elements, in which the neutralization agent is calcium carbonate and a calcium carbonate slurry with solid concentration of 270 kg/mto 350 kg/mis added to the exudate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of neutralizing a leachate produced by a hydrometallurgical process of nickel oxide ore, and a hydrometallurgical process of nickel oxide ore.

  There is a high pressure acid leaching method using sulfuric acid as a wet smelting method of nickel oxide ore (wet smelting process of nickel oxide ore). This method is different from the conventional smelting method of nickel oxide ore which is a smelting method, and it is an energy and cost advantage since it does not include a reduction and drying step and is a consistent wet step. In addition, it has the advantage of being able to obtain a nickel-containing sulfide (hereinafter also referred to as "nickel sulfide") which is highly purified to 50 to 60 mass% of nickel grade.

The hydrosmelting method of nickel oxide ore based on the above-mentioned high pressure acid leaching method includes, for example, the following steps.
(A) Sulfuric acid is added to the slurry of nickel oxide ore, leached under high temperature and high pressure, and the leaching residue is subjected to solid-liquid separation while multistage washing of the obtained leached slurry to contain nickel and metallic elements such as cobalt etc. A leaching step and a solid-liquid separation step to obtain a leachate,
(B) A neutralization step is carried out by adding a neutralizing agent to the leachate to carry out neutralization treatment, and separating the neutralized precipitate containing the impurity element to obtain a nickel-containing neutralization final solution,
(C) A sulfidation step of producing nickel sulfide by adding hydrogen sulfide gas to the final solution of neutralization, separating the nickel sulfide and recovering the nickel sulfide

  With regard to the neutralization step of the above-mentioned wet refining method of nickel oxide ore, for example, Patent Document 1 discloses calcium carbonate so that the pH becomes 4 or less while suppressing the oxidation of divalent iron ions present in the leachate. In addition to the simplification of the leaching process and the solid-liquid separation process, a neutralization precipitate slurry containing trivalent iron and a mother solution for recovering nickel (neutralization final solution) are added to the neutralization precipitation slurry. A technique for reducing the consumption of neutralizing agent is disclosed.

  However, in view of the need to reduce the basic unit, a method capable of further reducing the amount of neutralizing agent used in the neutralization step is desired.

JP 2005-350766 A

  The present invention has been proposed in view of the circumstances as described above, and can reduce the amount of the neutralizing agent used in the neutralization step of neutralizing the leachate in the wet smelting method of nickel oxide ore. An object of the present invention is to provide a neutralization treatment method and a hydrometallurgical method of nickel oxide ore using the same.

The present inventors diligently studied to solve the problems described above. As a result, the neutralizing agent is converted to calcium carbonate (CaCO ₃ ), and the calcium carbonate added to the leaching solution is converted to a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less. The inventors have found that the amount of neutralizing agent used in the neutralization step can be reduced because the efficiency can be increased, and the present invention has been completed. That is, the present invention provides the following.

(1) In the first invention of the present invention, a nickel oxide ore is leached with an acid to obtain a leached slurry containing a leachate containing nickel and a leaching residue, and then the leached slurry is subjected to solid-liquid separation treatment The resulting leachate is neutralized by adding a neutralizing agent to obtain a neutralized final solution containing nickel and a neutralized precipitate containing an impurity element, wherein the neutralizing agent Is calcium carbonate, and a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added to the leachate.

  (2) The second invention of the present invention is the neutralization treatment method according to the first invention, wherein the pH of the neutralization final solution is 2.5 to 3.0.

(3) The third invention of the present invention relates to the leaching step of subjecting nickel oxide ore to leaching treatment with an acid to obtain a leaching slurry containing a leaching solution containing nickel and a leaching residue, and the above obtained by the leaching step A solid-liquid separation step of subjecting the leached slurry to solid-liquid separation to obtain a leachate, and a neutralization agent is added to the leachate obtained in the solid-liquid separation step to neutralize the nickel-containing final solution And nickel having a neutralization step of obtaining a neutralized precipitate containing an impurity element, and a sulfide step of adding a sulfurizing agent to the neutralization final solution obtained in the neutralization step to form a sulfide containing nickel. A wet smelting method of oxide ore, wherein the neutralizing agent is calcium carbonate, and in the neutralization step, a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added to the leachate. Nickel oxide ore Hydrometallurgical method.

  According to the neutralization treatment method of the present invention, it is possible to reduce the amount of neutralizing agent used in the neutralization step of neutralizing the leachate in the hydrometallurgical method of nickel oxide ore. Therefore, the industrial value of the present invention is extremely high.

It is process drawing which shows the flow of the hydrometallurgy method of the nickel oxide ore in this Embodiment. It is a figure which shows the relationship between the solid substance concentration of a calcium carbonate slurry, and a calcium carbonate reaction efficiency.

  Hereinafter, specific embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention. Moreover, in this specification, the expression with "X-Y" (X and Y are arbitrary numerical values) is the meaning of "X or more and Y or less".

<< 1. Overview »
The neutralization treatment method according to the present embodiment is a neutralization treatment method in the neutralization step in a wet smelting process (hereinafter, also simply referred to as “wet smelting process”) of nickel oxide ore to obtain nickel sulfide. . The nickel sulfide is a sulfide containing nickel, and also includes a mixed sulfide of another metal such as cobalt and nickel.

Specifically, the neutralization step in the hydrometallurgical process of nickel oxide ore is carried out by adding a neutralizing agent to the leachate obtained by subjecting the nickel oxide ore to leaching treatment with acid and neutralizing it to the leachate by neutralization treatment. In this step, the impurities contained are used as a precipitate (neutralized precipitate) to obtain a neutralized final solution from which the impurities have been removed. And, in the neutralization processing method of the present embodiment, calcium carbonate is used as the neutralizing agent in this neutralization step, and calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is used in the leachate. It is characterized by adding. In the hydrometallurgical process of nickel oxide ore, the neutralized final solution obtained by such neutralization treatment is sulfurized and recovered as a sulfide containing nickel.

  According to such a method, the industrial value is extremely high because the amount of neutralizing agent used in the neutralization step in the hydrometallurgical process of nickel oxide ore can be reduced.

<< 2. Hydrometallurgical process of nickel oxide ore >>
First, prior to a more specific description of the neutralization treatment method, a wet smelting process of nickel oxide ore including the neutralization step to which this treatment method is applied will be described with reference to FIG. FIG. 1 is a process chart showing a flow of a hydrometallurgical method of nickel oxide ore in the present embodiment.

  As shown in FIG. 1, the hydrometallurgical method of nickel oxide ore adds sulfuric acid to raw material nickel oxide ore and performs leaching treatment with sulfuric acid under high temperature and high pressure to leach out leaching solution containing nickel and leaching residue A leaching step S1 for obtaining a slurry, a solid-liquid separation step S2 for obtaining a leachate containing nickel by separating a leaching residue from the leached slurry while performing multistage washing if necessary, a neutralization agent by adding a neutralizing agent to the leachate To obtain a neutralized final solution containing nickel and a neutralized precipitate containing an impurity element, and a sulfidation process S4 for adding a sulfiding agent to the neutralized final solution to form a sulfide containing nickel And.

(1) Leaching Step In the leaching step S1, sulfuric acid is added to the raw material nickel oxide ore, and leaching treatment is performed with sulfuric acid under high temperature and high pressure to obtain a leached slurry containing a leachate containing nickel and a leaching residue. For example, using a high temperature pressure reaction tank such as an autoclave, sulfuric acid is added to a slurry of nickel oxide ore (hereinafter also referred to as "ore slurry"), and a temperature of about 230 ° C to 270 ° C and a pressure of about 3MPa to 5MPa The mixture is stirred to form a leached slurry comprising a nickel-containing leachate and a leaching residue.

  As a raw material nickel oxide ore, so-called laterite ores such as limonite ore and saprolite ore are mainly mentioned. The nickel content of laterite ore is usually 0.8% by weight to 2.5% by weight and is contained as hydroxide or magnesium silicate mineral. The iron content is 10% by weight to 50% by weight, and is mainly in the form of a trivalent hydroxide, but part of divalent iron is contained in the siliceous earth mineral. Further, in the leaching step S1, in addition to such laterite ore, an oxide ore containing valuable metals such as nickel, cobalt, manganese, copper and the like, such as a manganese lump and the like stored on the deep sea floor can be used.

  In the leaching process in the leaching step S1, for example, a leaching reaction represented by the following formulas (a) to (e) and a high temperature hydrolysis reaction occur, leaching as a sulfate such as nickel or cobalt, and leached iron sulfate Immobilization as hematite is performed. However, since the immobilization of iron ions does not proceed completely, the liquid portion of the obtained leaching slurry usually contains divalent and trivalent iron ions in addition to nickel, cobalt and the like. Incidentally, in the leaching step S1, from the viewpoint of the filterability of the leaching residue containing hematite separated in the solid-liquid separation step S2 of the next step, the pH of the obtained leachate is adjusted to 0.1 to 1.0. It is preferable to do.

· Leaching reaction MO + H ₂ SO ₄ → MSO ₄ + H ₂ O · · · (a)
(Wherein, M represents Ni, Co, Fe, Zn, Cu, Mg, Cr, Mn, etc.)
2Fe (OH) ₃ + 3H ₂ SO ₄ → Fe ₂ (SO ₄ ) ₃ + 6H ₂ O · · · (b)
FeO + H ₂ SO ₄ → FeSO ₄ + H ₂ O · · · (c)
· High temperature hydrolysis reaction ₂ FeSO ₄ + H ₂ SO ₄ + _1/2 O ₂ → Fe ₂ (SO ₄ ) ₃ + H ₂ O · · · (d)
Fe ₂ (SO ₄ ) ₃ + 3H ₂ O → Fe ₂ O ₃ + 3H ₂ SO ₄ ·· (e)

  The amount of sulfuric acid added to an autoclave or the like charged with an ore slurry is not particularly limited, but an excessive amount is used so that iron in the ore is leached out. For example, the ratio is 300 kg to 400 kg per ton of ore.

(2) Solid-Liquid Separation Step In the solid-liquid separation step S2, the leached slurry generated in the leaching step S1 is washed in multiple stages to separate the leached residue, and a leachate containing valuable metals such as nickel and cobalt is obtained.

  In the solid-liquid separation step S2, for example, after the leached slurry is mixed with the cleaning liquid, solid-liquid separation processing is performed using a solid-liquid separation device such as a thickener. Specifically, the leaching slurry is first diluted by the washing solution, and then the leaching residue in the leaching slurry is concentrated as a thickener of thickener. Thereby, the nickel content adhering to the leaching residue can be reduced according to the degree of dilution. In addition, by separating and performing solid-liquid separation while using thickeners connected in multiple stages and performing multi-stage washing, it is possible to improve the recovery rate of nickel and cobalt to the washing liquid, that is, the leachate.

  As a multistage washing method in solid-liquid separation treatment, a continuous countercurrent washing method (CCD method) in which a nickel-free washing solution is brought into contact with a countercurrent is used. As a result, the amount of cleaning solution newly introduced into the system can be reduced, and the recovery rate of nickel and cobalt can be increased.

  The cleaning solution is not particularly limited, but a cleaning solution which does not contain nickel and does not affect the process can be used. Among them, it is preferable to use an aqueous solution having a pH of 1 to 3. When the pH of the washing solution is high, if aluminum is contained in the leaching solution, a bulky aluminum hydroxide is formed, which causes poor settling of the leaching residue in the thickener. As a washing | cleaning liquid, the poor solution of low pH (pH is about 1-3) obtained by sulfurization process S4 which is a post process can be utilized repeatedly.

  As a solid-liquid separation device, for example, a thickener that includes a sedimentation separation tank having an overflow part that discharges the supernatant liquid at the peripheral part, a cylindrical feedwell disposed vertically at the center part, and a stirring tank It can be used. The thickener is provided in multiple stages, and the leaching residue which is solid content is separated and removed while performing multistage washing of the slurry to be treated.

  The leachate obtained in the solid-liquid separation step S2 has, for example, an iron concentration of 2.4 to 6.0 g / L, an aluminum concentration of 3.0 to 6.7 g / L, and a magnesium concentration of 4.0 to 11.0 g / L, a sulfuric acid aqueous solution having a nickel concentration of 5.5 to 7.2 g / L and a manganese concentration of 4.0 to 5.5 g / L. The pH of the leachate is, for example, 0.4 to 0.9.

(3) Neutralization Step In the neutralization step S3, a neutralization agent is added to the leachate (neutralization start solution) obtained in the solid-liquid separation step S2 to perform neutralization treatment, and the neutralization final solution containing nickel And a neutralized precipitate containing an impurity element.

  Specifically, in the neutralization step S3, a neutralizing agent is added to the leaching solution to suppress oxidation of divalent iron ions present in the leaching solution, and as a neutralization final solution containing nickel and as an impurity element, for example, Form a neutralized precipitate slurry containing trivalent iron. In the neutralization step S3, the leaching solution is subjected to the neutralization treatment in this way to neutralize the excess acid used in the leaching treatment in the leaching step S1 to form a neutralized final solution and Impurity elements such as iron ions and aluminum ions remaining in the inside are removed as neutralized precipitates. A coagulant may be added to accelerate the settling speed of the neutralized precipitate slurry. The recovered neutralized precipitate slurry can be sent to the solid-liquid separation step S2. Thus, when nickel is contained in the neutralized precipitate slurry, nickel can be recovered also from the neutralized precipitate slurry. The leaching residue obtained in the solid-liquid separation step S2 may contain part of valuable metals such as nickel and cobalt. Accordingly, as shown by the dotted line in FIG. 1, a solution containing valuable metals such as nickel and cobalt obtained by washing the leaching residue may be supplied to the neutralization step S13.

Here, in the present embodiment, the neutralizing agent is calcium carbonate in the neutralization step S3, and a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added to the leachate. Although this will be described in detail later, the amount of the neutralizing agent used in the neutralization step can be reduced.

(4) Sulfurizing step In the sulfiding step S4, the sulfidation reaction is caused by adding the sulfiding agent such as hydrogen sulfide gas to the sulfidation reaction start solution as the sulfidation reaction start solution and blowing in the sulfiding agent. . As a result, a nickel sulfide having few impurity components and a sulfurization reaction final solution which is a poor liquid stabilized at a low concentration of nickel are formed, and the formed nickel sulfide is separated. When zinc is contained in the final solution, zinc is selectively separated as sulfide by using a sulfurizing agent prior to addition of the sulfurizing agent to separate nickel as nickel sulfide. Also good (dezincification process). That is, by adding a sulfiding agent to the neutralization final solution obtained in the neutralization step S3 in the sulfidation step S4, a zinc sulfide is formed and the zinc sulfide is separated to obtain a nickel recovery mother liquor containing nickel. It is good also as a process which has a nickel recovery process which produces nickel sulfide and separates this nickel sulfide by adding a sulfiding agent to a zinc removal process and a mother liquid for nickel recovery.

  As the sulfiding agent, for example, hydrogen sulfide, sodium sulfide, sodium hydrosulfide and the like can be used, and among them, it is particularly preferable to use a hydrogen sulfide gas in terms of ease of handling, cost and the like.

  The sulfurization treatment in the sulfurization step S4 can be performed using a sulfurization reaction tank or the like, and hydrogen sulfide gas is blown into the gas phase part in the reaction tank with respect to the sulfurization reaction start solution introduced into the sulfurization reaction tank It is possible to cause a sulfidation reaction gently by the hydrogen sulfide gas transferred therein. By this sulfidation treatment, nickel and cobalt contained in the initial solution of the sulfidation reaction are immobilized as sulfides.

  After completion of the sulfidation reaction, the obtained slurry containing nickel sulfide is charged into a filter device such as a filter press and subjected to a filtration treatment, and the sulfide is collected on a filter cloth. The aqueous solution component that has passed through the filter cloth is recovered as a poor solution. In order to reduce the amount of liquid passing through the filtration device, it is preferable to load the slurry in advance into a sedimentation concentration device such as a thickener and remove the supernatant liquid as a poor solution.

<< 3. About the neutralization process »
As described above, in the neutralization treatment in the neutralization step S3 of the wet smelting process, the leaching slurry produced in the leaching step S1 is subjected to solid-liquid separation in the solid-liquid separation step S2. Add to neutralize. Then, in the present embodiment, calcium carbonate is used as the neutralizing agent, and a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added to the leachate. At this time, preferably, the pH of the obtained neutralization final solution is in the range of 2.5 to 3.0.

The calcium carbonate slurry is a suspension obtained by mixing calcium carbonate with water. And in this specification, solid substance concentration (kg / m ³ ) of calcium carbonate slurry is obtained by dividing mass A (kg) of calcium carbonate contained in calcium carbonate slurry by volume B (m ³ ) of calcium carbonate slurry It is determined by That is, the solid concentration of the calcium carbonate slurry (kg / m ³ ) = A / B.

The calcium carbonate slurry used in the neutralization step of the present embodiment has a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less. The solid concentration of the calcium carbonate slurry is preferably 340 kg / m ³ or less and 280 kg / m ³ or more. When the solid concentration of the calcium carbonate slurry is 270 kg / m ³ or more and 350 kg / m ³ or less, the reaction efficiency of calcium carbonate represented by the following formula (1) is very high. In addition, as shown in Examples and Comparative Examples described later, in the range of 270 kg / m ³ or more and 350 kg / m ³ or less, as the solid concentration of the calcium carbonate slurry decreases, the carbonate represented by the following formula (1) The reaction efficiency of calcium increases. Therefore, using a calcium carbonate slurry with a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less can reduce the amount (addition amount) of calcium carbonate required for neutralization, and the amount of neutralizing agent used Can be reduced. In this embodiment, the reaction efficiency of calcium carbonate represented by the following formula (1) can be increased to 90% or more, and further to 95% or more. If the solid concentration of the calcium carbonate slurry exceeds 350 kg / m ³ , the reaction efficiency of the calcium carbonate is lowered, probably because the diffusivity of the calcium carbonate slurry in the leachate is deteriorated. For this reason, addition of a large amount of calcium carbonate is required for the neutralization treatment. Also, if the solid matter concentration of the calcium carbonate slurry is less than 270 kg / m ³ , the residence time is reduced, especially in the case of continuous treatment, because the calcium carbonate slurry concentration is low, conversely, the reaction efficiency of calcium carbonate is It falls sharply. And in a real operation, since calcium carbonate slurry concentration is thin that solid substance concentration is less than 270 kg / m ³ , it may take a long time to add the amount of calcium carbonate necessary for neutralization, for example, continuous treatment In this case, there may be a problem that the calcium carbonate slurry can not be supplied in time.
Reaction efficiency of calcium carbonate (%) = theoretical amount of calcium carbonate used (mol) / actual amount of calcium carbonate used (mol) (1)
Theoretical amount of calcium carbonate used (mol) ... theoretical value of the amount of calcium carbonate required for neutralization actual amount of calcium carbonate used (mol) ... amount of calcium carbonate actually added to leachate (neutralization start solution)

  In this neutralization treatment, it is preferable that the pH of the neutralization final solution obtained by adding the neutralizing agent to the leachate be in the range of 2.5 to 3.0. When the pH of the neutralization final solution is in the range of 2.5 to 3.0, the reaction efficiency of calcium carbonate is good. If the pH is less than 2.5, the reactivity in the sulfurization step S4 may be deteriorated. When the pH of the neutralization final solution exceeds 3.0, the reaction efficiency is low. In addition, when the pH of the neutralization final solution exceeds 3.0, fine precipitates are formed, and the clarity in the neutralization final solution decreases. The pH of the neutralization final solution is more preferably 2.7 to 2.9.

As described above, according to the neutralization treatment method of the present embodiment, the neutralizing agent is calcium carbonate, and calcium carbonate added to the leachate has a solid concentration of not less than 270 kg / m ^{3 and not} more than 350 kg / m ^3. By setting it as a calcium slurry, the reaction efficiency of the neutralization process can be increased, so the amount of the neutralizing agent used in the neutralization step can be reduced. And, by applying the neutralization treatment method of the present embodiment to the neutralization step in the wet smelting method of nickel oxide ore, the method is a wet smelting method of nickel oxide ore in which the amount of the neutralizing agent used is reduced. be able to.

  EXAMPLES Hereinafter, the present invention will be more specifically described with reference to examples, but the present invention is not limited to the following examples.

Example 1
A wet smelting process of the nickel oxide ore of the present invention shown in FIG. 1 was carried out. Specifically, as shown in FIG. 1, first, a slurry of nickel oxide ore is charged into an autoclave, and a leaching slurry containing a leachate and a leaching residue by performing leaching treatment using sulfuric acid under high temperature and high pressure. (Leaching step S1), solid-liquid separation treatment using a washing solution to obtain a leachate and a leaching residue slurry (solid-liquid separation step S2).

Next, a slurry of calcium carbonate having a solid concentration of 290 kg / m ³ is added to the obtained leachate to carry out neutralization treatment, thereby containing a neutralized final solution containing nickel and cobalt and an impurity element. A neutralized precipitate was obtained (neutralization step S3). The pH of the obtained neutralization final solution was 2.77.

  Then, a dezincification step of adding hydrogen sulfide gas as a sulfiding agent to the obtained neutralized final solution to separate generated zinc sulfide, and nickel formed by adding a hydrogen sulfide gas as a sulfiding agent after the dezincification step A nickel recovery step of recovering sulfides was sequentially performed (sulfurization step S4). In the nickel recovery step in the sulfurization step S4, nickel and cobalt in the neutralization final solution are sulfided to form a nickel-cobalt mixed sulfide. The formed sulfide was recovered by solid-liquid separation of the slurry after the sulfiding treatment by a thickener.

  The leachate (neutralization solution) has a pH of 0.5 to 0.9, an iron concentration of 2.4 to 5.8 g / L, an aluminum concentration of 3.0 to 6.7 g / L, and a magnesium concentration of 4. 1-10.7 g / L, nickel concentration was 5.7-7.2 g / L, and manganese concentration was 4.0-5.3 g / L. All other metal concentrations were less than 1.0 g / L.

  Moreover, when the reaction efficiency shown by said Formula (1) was calculated | required about neutralization process S3, it was 98.8%.

[Examples 2-14 and Comparative Examples 1-7]
The same operation as in Example 1 was performed except that the solid concentration of the calcium carbonate slurry was changed to the value shown in Table 1. In addition, the ratio (volume of calcium carbonate slurry / volume of leachate) of the volume of calcium carbonate slurry added to the volume of leachate (neutralization start solution) is the same condition (17 in Examples 1 to 14 and Comparative Examples 1 to 7). Volume%).

  Table 1 shows the pH of the neutralization final solution obtained in the neutralization step, the solid concentration of the calcium carbonate slurry, and the calcium carbonate reaction efficiency. Moreover, the relationship between the solid substance concentration of a calcium carbonate slurry and the calcium carbonate reaction efficiency is shown in FIG.

As shown in Table 1 and FIG. 2, in Examples 1 to 14 in which a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added, the calcium carbonate reaction efficiency is as high as 90% or more. Met. And in the calcium carbonate slurry solid substance concentration range of Examples 1-14, the rise of the reaction efficiency of calcium carbonate was seen as the solid substance concentration of a calcium carbonate slurry fell. On the other hand, in Comparative Examples 1 to 7 in which a calcium carbonate slurry not having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less was added, the calcium carbonate reaction efficiency was significantly lower than in Examples 1 to 14. .

From the above results, it can be seen that the calcium carbonate reaction efficiency is high when a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added to the neutralization step. Therefore, using a calcium carbonate slurry with a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less can reduce the amount (addition amount) of calcium carbonate required for neutralization, and the amount of neutralizing agent used Can be reduced.

Claims (3)

A nickel oxide ore is subjected to acid leaching treatment to obtain a leaching slurry containing a nickel-containing leaching solution and a leaching residue, and then a neutralizing agent is added to the leaching solution obtained by solid-liquid separation treatment of the leaching slurry. And subjecting to neutralization treatment to obtain a neutralization final solution containing nickel and a neutralization deposit containing an impurity element,
The neutralization process method of adding the calcium carbonate slurry whose solid concentration is 270 kg / m ³ or more and 350 kg / m ³ or less, wherein the neutralizing agent is calcium carbonate, and the solid solution concentration is in the leachate. The neutralization treatment method according to claim 1, wherein the pH of the neutralization final solution is 2.5 to 3.0. A leaching step of subjecting nickel oxide ore to acid leaching treatment to obtain a leaching slurry containing a leaching solution containing nickel and a leaching residue, and subjecting the leaching slurry obtained in the leaching step to solid-liquid separation treatment to obtain a leachate A neutralizing agent is added to the above-mentioned leachate obtained in the solid-liquid separation step to be obtained and the solid-liquid separation step to perform neutralization treatment to obtain a nickel-containing neutralization final solution and a neutralization precipitate containing an impurity element A wet smelting method of nickel oxide ore comprising a neutralization step, and a sulfiding step of adding a sulfiding agent to the neutralization final solution obtained in the neutralization step to form a sulfide containing nickel,
The wet refining method of nickel oxide ore, wherein the neutralizing agent is calcium carbonate, and in the neutralizing step, a calcium carbonate slurry having a solid concentration of 270 kg / m ³ or more and 350 kg / m ³ or less is added to the leachate.

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