JP5637294B1 - Neutralization method - Google Patents

Abstract

[Problem] To provide a treatment method capable of performing an efficient neutralization treatment by suppressing the amount of use of a high-cost, high-alkali neutralizing agent in wastewater treatment in a sulfidation process of a hydrometallurgical method of nickel oxide ore. It is generated from a treatment process in which hydrogen sulfide is blown into a sulfuric acid aqueous solution containing nickel and cobalt and an impurity metal element containing at least one of iron, magnesium and manganese to form a sulfide of nickel and cobalt. A neutralization treatment method for neutralizing and removing metal ions remaining in a poor solution, wherein a calcium carbonate slurry is used as a first neutralizer for the poor solution, and the pH is in a range of 5.0 to 6.0. The neutralization treatment is performed on the solution obtained in the first neutralization treatment step S11 and the first neutralization treatment step using a sodium carbonate solution as the second neutralizing agent. And a second neutralization treatment step S12 for obtaining a precipitate containing metal remaining in the poor solution and a neutralized final solution from which metal ions have been removed. [Selection] Figure 2

Description

  The present invention relates to a neutralization treatment method, and more particularly, a poor liquid obtained from a sulfidation treatment in which hydrogen sulfide gas is blown into a sulfuric acid aqueous solution containing nickel and cobalt and an impurity metal element to form a sulfide containing nickel and cobalt. The present invention relates to a neutralization treatment method for neutralizing and removing residual impurity metal ions therein.

  In recent years, high pressure acid leaching using sulfuric acid has attracted attention as a method for hydrometallizing nickel oxide ore. Unlike the conventional dry smelting method, which is a conventional nickel oxide ore smelting method, this method does not include dry processes such as reduction and drying processes, and is a consistent wet process. This is advantageous. Further, there is an advantage that a sulfide containing nickel (hereinafter also referred to as “nickel sulfide”) whose nickel quality is improved to about 50% by weight can be obtained. This nickel sulfide is precipitated by purifying the leachate obtained by leaching the nickel oxide ore and then blowing hydrogen sulfide gas in the sulfidation step to cause a sulfidation reaction (see, for example, Patent Document 1). .)

  By the way, in the sulfidation step of the nickel oxide ore hydrometallurgical process, as described above, by performing a sulfidation treatment in which hydrogen sulfide gas is blown into a sulfuric acid aqueous solution mainly containing nickel, the sulfide containing nickel and the nickel concentration Can be obtained at a low level.

  The poor solution obtained in the sulfidation step is a solution having a low pH and containing impurities such as iron, magnesium, and manganese remaining without being sulfidized. Therefore, in discharging this poor solution, it is necessary to carry out a neutralization treatment for removing residual metal ions.

  Conventionally, as a method of neutralizing this poor solution, a method of neutralizing mainly using one type of neutralizing agent has been used. In this method, it was necessary to use a highly alkaline neutralizing agent in order to achieve the pH required for neutralization. Specifically, examples of the highly alkaline neutralizer include caustic soda and sodium carbonate, but they are disadvantageous in terms of cost, and industrially, for example, slaked lime slurry is often used.

  However, such a highly alkaline neutralizing agent is generally packed in a flexible container or the like, and complicated use of pretreatment and pretreatment equipment is required when the amount of use increases. Moreover, even if it is a neutralizer such as slaked lime slurry, which is advantageous in terms of cost compared with other neutralizers, the amount of poor liquid generated from the sulfidation process increases, and the amount of neutralizer used is enormous. In such a case, there is a problem that the influence on the finishing cost is large.

JP-A-2005-350766

  The present invention has been proposed in view of such a situation, and is in a poor solution generated from a processing step of forming a sulfide of nickel and cobalt from a sulfuric acid aqueous solution containing nickel and cobalt and an impurity metal element. Provided is a neutralization treatment method capable of performing an efficient neutralization treatment by reducing the amount of a high-cost, highly alkaline neutralizing agent used in the sum treatment.

  As a result of intensive studies in order to achieve the above-described object, the present inventors have obtained a part of the neutralizing agent used, for example, a sodium carbonate solution in the neutralization removal treatment of the impurity metal element in the poor solution. We found that it is possible to reduce the amount of high-cost neutralizing agent used by substituting inexpensive calcium carbonate slurry and performing stepwise neutralization with adjusted end point pH using the two types of neutralizing agents. The present invention has been completed.

  That is, in the neutralization treatment method according to the present invention, hydrogen sulfide gas is blown into a sulfuric acid aqueous solution containing nickel and cobalt and an impurity metal containing at least one of iron, magnesium, and manganese. A neutralization treatment method for neutralizing and removing metal ions remaining in a poor solution obtained from a sulfurization treatment for forming a sulfide containing sulfide, wherein a calcium carbonate slurry is used as a first neutralizer for the poor solution. Use as a second neutralizing agent in the solution obtained in the first neutralization treatment step in which the neutralization treatment is performed with the end point in the range of pH 5.0 to 6.0 and the first neutralization treatment step. A second neutralization treatment step of performing a neutralization treatment using a sodium carbonate solution to obtain a precipitate containing a metal remaining in the poor solution and a neutralized final solution from which the metal ions have been removed; It is characterized by.

  Here, it is preferable to make pH of the end point in the said 1st neutralization process into the range of 5.4-5.8.

  In the second neutralization step, the neutralization treatment is preferably performed with a pH range of 8.5 to 9.5 as an end point.

  In addition, the sulfuric acid aqueous solution includes nickel and cobalt recovered through a leaching step, a solid-liquid separation step, and a neutralization step in a hydrometallurgical method based on high-temperature pressure leaching for recovering nickel from nickel oxide ore, and iron. , A mother liquor composed of an aqueous sulfuric acid solution containing an impurity metal containing at least one of magnesium and manganese.

  ADVANTAGE OF THE INVENTION According to this invention, the usage-amount of a high cost highly alkaline neutralizing agent can be reduced, and the neutralization process which neutralizes and removes the impurity metal element in a poor liquid can be performed efficiently.

It is process drawing of the hydrometallurgical method by the high temperature pressurization acid leaching method of nickel oxide ore. It is process drawing of the neutralization processing method which concerns on this invention.

Hereinafter, the neutralization treatment method according to the present invention will be described in detail in the following order with reference to the drawings. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary of this invention, it can change suitably.
1. 1. Outline of the present invention 2. Hydrometallurgical method of nickel oxide ore 3. Neutralization treatment method 3-1. First neutralization treatment step 3-2. Second neutralization treatment step 4. Example

<< 1. Outline of the present invention >>
The neutralization treatment method according to the present invention includes a hydrogen sulfide gas blown into a sulfuric acid aqueous solution containing nickel and cobalt and an impurity metal containing at least one of iron, magnesium and manganese, and sulfide containing nickel and cobalt. It is intended to neutralize and remove residual impurity metal ions in the poor solution obtained from the sulfiding treatment that forms the product.

  Specifically, this neutralization treatment method uses a calcium carbonate slurry as a first neutralizing agent for the above-described poor solution, and performs neutralization treatment with a pH range of 5.0 to 6.0 as an end point. The neutralization process of the neutralization process of 1 and the solution obtained by the 1st neutralization process process is neutralized using a sodium carbonate solution as a 2nd neutralizer, and the metal which remained in the poor liquid is included. A second neutralization treatment step for obtaining a neutralized final solution from which the precipitate and its metal ions have been removed.

  As described above, it is important for the neutralization treatment method according to the present invention to perform a stepwise neutralization treatment using two kinds of neutralizing agents with a predetermined pH range as an end point. Then, one of the two types of neutralizing agents is used as a calcium carbonate slurry that is an inexpensive neutralizing agent, and the first stage of neutralization is performed using the calcium carbonate slurry.

  According to such a neutralization treatment method, first, neutralization treatment is performed using an inexpensive calcium carbonate slurry as an end point with a predetermined pH range as the first neutralization treatment. The amount of highly alkaline neutralizing agent such as slaked lime slurry can be effectively reduced, and impurity metal ions can be efficiently neutralized and removed. Thereby, even if it is a case where the amount of poor liquids which should be processed increases, the excessive increase in processing cost can be prevented and efficient processing can be performed.

≪2. Method of hydrometallizing nickel oxide ore >>
The sulfuric acid aqueous solution containing nickel and cobalt described above and an impurity metal element is not particularly limited and can be widely applied. For example, in a hydrometallurgical method based on high-temperature pressure leaching to recover nickel from nickel oxide ore. A mother liquor comprising an aqueous sulfuric acid solution containing nickel and cobalt recovered through a leaching step, a solid-liquid separation step, and a neutralization step, and an impurity metal containing at least one of iron, magnesium, and manganese be able to.

  And the neutralization processing method which concerns on this Embodiment is a hydrogen sulfide with respect to the mother liquid which consists of the sulfuric acid aqueous solution which contains the nickel and cobalt obtained in this hydrometallurgy method of nickel oxide ore, and an impurity metal, for example A poor liquid discharged from a sulfiding step of blowing gas and forming a sulfide containing nickel and cobalt can be used as a treatment target.

  Here, the outline of the hydrometallurgical method of nickel oxide ore will be described. Here, the hydrometallurgical method using the high-temperature pressure acid leaching method will be described as a specific example.

  FIG. 1 shows an example of a process diagram of a hydrometallurgical smelting method by high-temperature pressure acid leaching of nickel oxide ore. As shown in FIG. 1, the hydrometallurgical method of nickel oxide ore includes a leaching step S1 for leaching nickel or the like from nickel oxide ore, and solid-liquid separation for separating the obtained leaching slurry into a leaching solution and a leaching residue. Step S2, neutralization step S3 for neutralizing the leachate and separating it into a nickel recovery mother liquor and a neutralized starch slurry, and hydrogen sulfide gas is blown into the sulfuric acid aqueous solution as the mother liquor to perform nickel sulfide and cobalt. And a sulfiding step S4 for obtaining a sulfide and a poor solution.

(1) Leaching step In the leaching step S1, sulfuric acid is added to the nickel oxide ore slurry, and the mixture is stirred at a temperature of 220 to 280 ° C. to form a leaching slurry composed of a leaching solution and a leaching residue. In the leaching step S1, for example, a high-temperature pressurized container (autoclave) is used.

  Examples of the nickel oxide ore used in the leaching step S1 include so-called laterite ores such as limonite ore and saprolite ore. The nickel content of the laterite ore is usually 0.8 to 2.5% by weight, and is contained as a hydroxide or a siliceous clay (magnesium silicate) mineral. Further, the iron content is 10 to 50% by weight and is mainly in the form of trivalent hydroxide (goethite), but partly divalent iron is contained in the siliceous clay.

  Specifically, in the leaching step S1, a leaching reaction and a high-temperature thermal hydrolysis reaction represented by the following formulas (1) to (5) occurred, and leaching as sulfates such as nickel and cobalt was leached. Immobilization of iron sulfate as hematite is performed. However, since the immobilization of iron ions does not proceed completely, the leaching slurry obtained usually contains divalent and trivalent iron ions in addition to nickel, cobalt and the like.

・ Leaching reaction MO + H ₂ SO ₄ ⇒ MSO ₄ + H ₂ O (1)
(In the formula, 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 (2)
FeO + H ₂ SO ₄ ⇒ FeSO ₄ + H ₂ O (3)
High temperature thermal hydrolysis reaction 2FeSO ₄ + H ₂ SO ₄ + 1 / 2O ₂ ⇒ Fe ₂ (SO ₄ ) ₃ + H ₂ O (4)
_{Fe 2 (SO 4) 3 +} 3H 2 O⇒ Fe 2 O 3 + 3H 2 SO 4 ··· (5)

  The slurry concentration in the leaching step S1 is not particularly limited, but it is preferably prepared so that the slurry concentration of the leaching slurry is 15 to 45% by weight. Moreover, the addition amount of sulfuric acid used in the leaching step S1 is not particularly limited, and an excessive amount is used so that iron in the ore is leached. For example, it is 300 to 400 kg per ton of ore. If the amount of sulfuric acid added per ton of ore exceeds 400 kg, the sulfuric acid cost increases, which is not preferable.

(2) Solid-liquid separation step In the solid-liquid separation step S2, the leaching slurry formed in the leaching step S1 is washed in multiple stages to obtain a leaching solution containing nickel and cobalt and a leaching residue.

  The multi-stage cleaning method in the solid-liquid separation step S2 is not particularly limited, but it is preferable to use a continuous alternating current cleaning method (CCD method: Counter Current Decantation) in which a counter current is brought into contact with a cleaning liquid not containing nickel. As a result, the cleaning liquid newly introduced into the system can be reduced, and the recovery rate of nickel and cobalt can be 95% or more.

(3) Neutralization step In the neutralization step S3, the pH of the leachate is 4.0 or less, preferably 3.2 to 3.8, while suppressing oxidation of the leachate separated in the solid-liquid separation step S2. Calcium carbonate is added so as to form a mother liquor for nickel recovery and a neutralized starch slurry containing trivalent iron. In the neutralization step S3, the neutralization treatment of the leachate is performed in this manner, so that the excess acid used in the leaching step S1 by high-temperature pressure acid leaching is neutralized, and the trivalent remaining in the solution Remove iron and aluminum ions. When the pH of the leachate exceeds 4.0, the generation of nickel hydroxide increases.

  The neutralized starch slurry obtained in the neutralization step S3 can be sent to the solid-liquid separation step S2 as necessary. Thereby, nickel contained in the neutralized starch slurry can be effectively recovered. Specifically, by repeating the neutralized starch slurry to the solid-liquid separation step S2 operated at a low pH condition, the neutralized starch adhering water and the neutralized starch surface are simultaneously cleaned with the leaching residue. The dissolution of nickel hydroxide produced by the local reaction can be promoted, and the nickel content that causes recovery loss can be reduced.

(4) Sulfurization step In the sulfurization step S4, hydrogen sulfide gas is blown into the sulfuric acid aqueous solution, which is the mother liquor for nickel recovery obtained in the neutralization step S3, to cause a sulfidation reaction. And generate

  When zinc is contained in the mother liquor, the zinc can be selectively separated as sulfides prior to the formation of nickel and cobalt sulfides by the sulfurization reaction. As a process for selectively separating this zinc, by creating weak conditions during the sulfidation reaction and suppressing the speed of the sulfidation reaction, the coprecipitation of nickel with a high concentration compared to zinc is suppressed, and zinc is selectively used. To remove.

  The mother liquor is an aqueous sulfuric acid solution containing nickel and cobalt obtained by leaching out nickel oxide ore and neutralizing step S3 as described above. Specifically, for example, the pH is 3.2 to 4.0, the nickel concentration is 2 to 5 g / L, the cobalt concentration is 0.1 to 1.0 g / L, and as impurity components, for example, iron, An aqueous sulfuric acid solution containing an impurity metal element containing at least one of magnesium and manganese can be used. Impurity metal components vary greatly depending on the redox potential of leaching, the operating conditions of the autoclave, and the ore quality, but generally contain about several g / L of iron, magnesium, manganese, and other impurity metal elements. Yes.

  Here, the alkaline metal such as iron, manganese, alkali metal, and magnesium, which are impurity metal components contained in the sulfuric acid aqueous solution, is present in a relatively large amount with respect to the recovered nickel and cobalt. The stability as the sulfide formed is low. Therefore, these metal impurities are not contained in the formed sulfide, but are contained in a poor solution (sulfurization treatment final solution) obtained by removing the formed sulfide. The poor solution has a pH of about 1.0 to 3.0.

  Thus, in the sulfidation step S4, a sulfide containing nickel and cobalt with a small amount of impurities and a poor liquid with a nickel concentration stabilized at a low level are generated and recovered. As a recovery method, the sulfide slurry obtained by the sulfidation reaction is subjected to sedimentation treatment using a sedimentation separator such as thickener, whereby the sulfide as a precipitate is separated and recovered from the bottom of the thickener, and the aqueous solution component is recovered. Overflow and recovered as poor liquid.

≪3. Neutralization method >>
As described above, the poor solution obtained through the sulfidation step S4 of the nickel oxide ore hydrometallurgical process contains impurities metal ions containing at least one of iron, magnesium, and manganese. Therefore, in discharging this poor solution out of the system, it is necessary to perform a neutralization treatment for removing residual metal ions in the poor solution. Further, even when this poor solution is repeatedly used in the above-described hydrometallurgy, it is preferable to perform a neutralization treatment in order to reduce the impurity components as much as possible.

  Conventionally, the neutralization treatment for the poor solution has been performed using a highly alkaline neutralizing agent such as a sodium carbonate solution in order to achieve the pH necessary for neutralization. However, such a highly alkaline neutralizing agent requires complicated pretreatment and pretreatment facilities when the amount of poor liquid generated from the sulfurization step S4 increases and the amount of use increases. Moreover, even if it is a neutralizing agent such as a sodium carbonate solution that is relatively advantageous in terms of cost with respect to other neutralizing agents, when the amount of poor liquid to be treated increases, There is a problem that the degree of influence on the finishing cost is large.

  Therefore, in the neutralization treatment method according to the present invention, for example, a part of the neutralizing agent used, such as a sodium carbonate solution, is replaced with an inexpensive calcium carbonate slurry, and step-by-step using the two types of neutralizing agents. Perform sum processing.

  Specifically, as shown in the process diagram of FIG. 2, this neutralization treatment method uses a calcium carbonate slurry as a first neutralizer for the poor solution, and neutralizes with a predetermined pH range as an end point. A neutralization treatment using a sodium carbonate solution as a second neutralizing agent is performed on the solution obtained in the first neutralization treatment step S11 and the first neutralization treatment step S11. And a second neutralization treatment step S12 for producing a precipitate and a neutralized final solution.

<3-1. First neutralization treatment step>
In the first neutralization treatment step S11, a calcium carbonate slurry is used as a neutralizing agent, and a neutralization treatment is performed on the poor liquid obtained through the above-described sulfurization step S4.

  The calcium carbonate slurry used in the first neutralization treatment step S11 is an inexpensive neutralizer. Therefore, this inexpensive calcium carbonate slurry is used as the first neutralizing agent, and by first performing the first-stage neutralization treatment, the highly alkaline neutralization used in the second-stage neutralization treatment described later. The amount of the agent used can be reduced.

  In the first neutralization treatment in this stepwise neutralization treatment, it is important to perform the neutralization treatment by adjusting a predetermined pH range as the end point of the neutralization reaction. Specifically, in the first neutralization treatment step S11, the neutralization treatment is performed with the pH at the end point being in the range of 5.0 to 6.0, preferably in the range of 5.4 to 5.8.

  Thus, in 1st neutralization process S11, while using calcium carbonate slurry as a neutralizer, the neutralization process of the 1st step which set and adjusted the pH of the end point to 5.0-6.0 I do. As a result, the amount of highly alkaline neutralizing agent used can be reduced as described above, and the total amount of neutralizing agent used in the entire neutralization treatment can be reduced to reduce the processing cost and thereby achieve an efficient neutralization treatment. It can be performed. And thereby, even if it is a case where the amount of poor liquids which should be processed increases, the excessive increase in processing cost can be prevented.

  Here, regarding the pH at the end point in the first neutralization treatment, if the pH is less than 5.0, the first neutralization treatment becomes insufficient and the second neutralization treatment step S12 described later is performed. The load of the sum treatment increases, and as a result, the amount of the second neutralizing agent used increases. On the other hand, if the pH at the end point exceeds 6.0, the load of the first neutralization treatment increases, and the amount of calcium carbonate slurry used increases. Even when the end point pH is adjusted to exceed 6.0 to increase the load of the first neutralization treatment, the amount of the neutralizing agent used in the second neutralization treatment step S12 is almost the same. Since it does not change, the amount of neutralizing agent used in the entire neutralization treatment increases, making it economically inefficient.

  Preferably, the neutralization treatment in the first neutralization treatment and the neutralization treatment in the second neutralization treatment are performed by performing the neutralization treatment in the first stage with the pH range of 5.4 to 5.8 as an end point. The amount of the agent used can be reduced more effectively, and an efficient treatment can be performed without excessively increasing the treatment cost even when the amount of poor liquid to be treated is increased.

  In addition, the measurement of pH is not specifically limited, It can measure using a well-known method and can determine the end point of the neutralization process based on the measured pH. For example, a pH meter is installed in the neutralization reaction tank to enable measurement of the pH of the solution in the reaction tank as needed, and the pH that changes as the neutralization reaction progresses with the addition of the neutralizing agent is observed. Determine the end point of the process.

<3-2. Second neutralization treatment step>
In the second neutralization treatment step S12, the solution obtained through the first neutralization treatment step S11 is neutralized using a sodium carbonate solution as a second neutralizing agent. By this second neutralization treatment, a precipitate containing the impurity metal and a neutralized final solution from which the impurity metal has been removed are generated.

  As described above, conventionally, neutralization treatment was performed using only a highly alkaline neutralizing agent such as a sodium carbonate solution, but the amount of neutralizing agent required increased due to an increase in the number of poor solutions to be treated. Even when an inexpensive sodium carbonate solution is used, the treatment cost is excessively increased, and the treatment with high economic efficiency cannot be performed. In contrast, in the neutralization treatment method according to the present embodiment, as described above, first, in the first neutralization treatment step S11, the neutralization treatment with the predetermined pH range as the end point is performed using the calcium carbonate slurry. Therefore, the amount of highly alkaline neutralizing agent such as sodium carbonate solution used in the second neutralization treatment can be effectively reduced. Thereby, even when the amount of the poor liquid to be processed increases, an excessive increase in the processing cost can be prevented and efficient processing can be performed.

  In the neutralization treatment in the second neutralization treatment step S12, it is preferable to adjust the pH range of the end point to a pH range of 8.5 to 9.5.

  When the pH at the end point in the second neutralization treatment is less than 8.5, precipitates of iron, magnesium, manganese and other impurity metal elements contained in the poor solution are not sufficiently formed, and the impurity metal ions are in the middle. There is a possibility of remaining in the final solution. On the other hand, when the pH of the end point exceeds 9.5, precipitation of impurity metals does not proceed further, and the load of neutralization treatment increases and the amount of sodium carbonate solution used as the second neutralizing agent is increased. Will increase the economy.

  Moreover, preferably, the neutralization process of the 2nd step is performed by making the range of pH 8.9-9.1 into an end point. This makes it possible to effectively form a precipitate of the impurity metal element in the poor liquid while minimizing the amount of the second neutralizing agent used, and to perform a more efficient neutralization removal treatment. be able to.

  In addition, regarding the pH control in the second neutralization treatment step S12, the end point of the neutralization treatment is determined using a known method in the same manner as the pH measurement in the first neutralization treatment step S11 and the pH management based thereon. be able to.

  The precipitate containing the impurity metal element obtained through the second neutralization treatment step S12 and the neutralized final solution from which the impurity metal has been removed are separated and recovered by performing a known solid-liquid separation treatment. be able to.

<< 4. Examples >>
Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[Example 1]
In a wet smelting method of nickel oxide ore, a mother liquor composed of an aqueous sulfuric acid solution containing nickel and cobalt recovered through a leaching step, a solid-liquid separation step, and a neutralization step, and iron, magnesium, manganese and other impurity metals On the other hand, after performing a sulfidation process in which hydrogen sulfide gas is blown to form a sulfide containing nickel and cobalt, impurity metal ions contained in the poor liquid are removed from the poor liquid discharged from the sulfidation process. A neutralization treatment for neutralization and removal was performed.

Specifically, in the neutralization treatment in Example 1, first, 3 mol / L calcium carbonate slurry is added as a first neutralizer to the poor solution 1 m ³ (pH 1.7), and the end point pH is 5 The first neutralization treatment was performed to neutralize until 0.5 (end point pH (1)).

  Subsequently, a 3 mol / L sodium carbonate solution is added as a second neutralizing agent to the solution after the first neutralization treatment, and the end point pH is 9.0 (end point pH (2)). A second neutralization treatment for neutralization was performed. At this time, the addition amount of each neutralizing agent used by the 1st neutralization process and the 2nd neutralization process was calculated | required.

[Comparative Example 1]
In Comparative Example 1, the neutralization treatment was performed in the same manner as in Example 1 except that the end point pH in the first neutralization treatment was 6.5 (end point pH (1)). The amount added was determined.

[Comparative Example 2]
In Comparative Example 2, the pH of the end point is 9.0 (only one stage, but for convenience, “end point pH (2)”) using only a sodium carbonate solution as a neutralizing agent in 1 m ³ of the poor solution. The neutralization process was performed until it became, and the addition amount of the neutralizer required at this time was calculated | required.

  Table 1 shows the results of the amount of neutralizing agent added in Example 1, Comparative Example 1 and Comparative Example 2.

  As can be seen from the results shown in Table 1, during the first stage, calcium carbonate slurry was used as the first neutralizing agent, and the pH at the end point was adjusted to pH 5.5, which is in the range of 5.0 to 6.0. In Example 1 in which the neutralization treatment was performed and then the second neutralization treatment was performed using a highly alkaline sodium carbonate solution as the second neutralizing agent, the amount of sodium carbonate solution added was 67 L, and the efficiency I was able to perform a typical process. The total amount of neutralizing agent used in the entire neutralization treatment is 150 L (= 83 L + 67 L), of which 83 L is an inexpensive calcium carbonate slurry used in the first stage neutralization treatment. The amount of sodium solution used could be reduced, and the treatment cost of the entire neutralization treatment could be greatly reduced.

  On the other hand, although two-step neutralization treatment was performed using two types of neutralizing agents in the same manner as in Example 1, in Comparative Example 1 where the end point pH of the first neutralization treatment was 6.5, The load of neutralization treatment in the first stage increased, and the amount of calcium carbonate slurry added was 235 L, which was 2.5 times or more that of Example 1. In Comparative Example 1, the amount of the sodium carbonate solution used for the neutralization treatment in the second stage was 61 L in spite of increasing the load of the neutralization treatment in the first stage. The total amount of neutralizing agent used in the entire neutralization treatment was significantly increased, and an efficient neutralization treatment could not be performed.

  Moreover, in the comparative example 2 which performed the neutralization process only using the sodium carbonate solution similarly to the past, the addition amount of the sodium carbonate solution reached 144L. The amount of sodium carbonate solution used is equivalent to twice or more the amount of sodium carbonate solution used in Example 1. Although the amount of neutralizing agent used in Comparative Example 2 is almost the same as the total amount of neutralizing agent used in Example 1, stepwise neutralization using an inexpensive calcium carbonate slurry as the first neutralizing agent. Compared with Example 1 in which Comparative Example 2 was carried out, the processing cost was much higher in Comparative Example 2. In such a process, it is considered that the processing cost is remarkably increased as the amount of poor liquid to be processed increases.

Claims (4)

Poorness obtained from a sulfidation treatment in which hydrogen sulfide gas is blown into a sulfuric acid aqueous solution containing nickel and cobalt and an impurity metal containing at least one of iron, magnesium and manganese to form a sulfide containing nickel and cobalt A neutralization treatment method for neutralizing and removing metal ions remaining in the liquid,
For the poor solution, a first neutralization treatment step using a calcium carbonate slurry as a first neutralizer and performing a neutralization treatment with a pH range of 5.0 to 6.0 as an end point;
The solution obtained in the first neutralization treatment step is neutralized using a sodium carbonate solution as a second neutralizing agent, and the precipitate containing the metal remaining in the poor solution and the metal ion And a second neutralization treatment step for obtaining a neutralized final solution from which water has been removed.   The neutralization method according to claim 1, wherein the end point pH in the first neutralization step is in the range of 5.4 to 5.8.   The neutralization treatment method according to claim 1 or 2, wherein in the second neutralization step, neutralization treatment is performed with a pH range of 8.5 to 9.5 as an end point.   In the hydrometallurgical method based on high-temperature pressure leaching for recovering nickel from nickel oxide ore, the aqueous sulfuric acid solution is nickel and cobalt recovered through a leaching step, a solid-liquid separation step, and a neutralization step, and iron and magnesium. 4. The neutralization treatment method according to claim 1, wherein the neutralization treatment method is a mother liquor comprising an aqueous sulfuric acid solution containing an impurity metal containing at least one of manganese and at least one of manganese.

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