JP2018079435A - Neutralization treatment method - Google Patents

Abstract

[PROBLEMS] To reduce the amount of slaked lime slurry, which is a high-cost, strong alkaline neutralizing agent, in an efficient neutralization treatment for neutralizing and removing ions of a metal from a sulfuric acid solution containing an impurity metal. A method of performing sum processing is provided. A neutralization treatment method according to the present invention is a neutralization treatment method for neutralizing and removing metal ions from a sulfuric acid acidic solution containing at least one of iron, magnesium and manganese. A first neutralization treatment step in which a calcium carbonate slurry is used as a first neutralizer for a sulfuric acid acidic solution and a neutralization treatment is performed with a pH range of 5.0 to 6.0 as an end point; and a second neutralizer A second neutralization treatment step for obtaining a precipitate containing a metal contained in the sulfuric acid acidic solution and a neutralized final solution from which the metal ions have been removed, by performing neutralization treatment using slaked lime slurry as Have. In the second neutralization treatment step, neutralization treatment is performed using slaked lime slurry having a solid concentration (% Solid) range of 10% to 18%. [Selection] Figure 2

Description

  The present invention relates to a neutralization treatment method, and more specifically, obtained from a sulfurization treatment in which hydrogen sulfide gas is blown into a sulfuric acid 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 in a poor solution.

  As a hydrometallurgical method of nickel oxide ore, there is a method using a high pressure acid leaching method in which leaching is performed with an acid such as sulfuric acid under high temperature and high pressure. Unlike the conventional dry smelting method, which is a conventional nickel oxide ore smelting method, this method does not include reduction and drying steps, and consists of a consistent wet process. It is advantageous. In addition, there is an advantage that a sulfide containing nickel and cobalt whose nickel quality is increased to about 50% by mass (hereinafter also referred to as “nickel cobalt mixed sulfide”) can be obtained.

Specifically, as a hydrometallurgical method using a high pressure acid leaching method, for example, the following steps are included.
(A) A leaching step of adding an acid such as sulfuric acid to a nickel oxide ore slurry (ore slurry) and performing a leaching treatment under high temperature and high pressure to obtain a leaching slurry containing a leaching solution and a leaching residue (b) Multistage leaching slurry Solid-liquid separation step of separating the leach residue while washing and obtaining a leachate containing impurity elements together with nickel and cobalt (c) Adjusting the pH by adding a neutralizing agent to the separated leachate and producing it by the neutralization treatment In order to accelerate the sedimentation rate of the neutralized starch containing the impurity element to be added, a part of the leaching residue slurry and a coagulant are added, and then the neutralized starch is separated to obtain a noble liquid containing nickel and cobalt Neutralization step (d) A nickel solution in which a sulfide containing nickel and cobalt is generated and separated by adding a sulfurizing agent such as hydrogen sulfide gas to a noble liquid containing nickel and cobalt. Step (e) mixed sulfide remaining to poor solution after the recovery, iron, magnesium, wastewater neutralization step to remove impurities such as manganese

  Now, in the hydrometallurgical method having the above-described steps, in order to neutralize the poor liquid recovered through the nickel recovery step (drainage neutralization step), in order to achieve the pH necessary for neutralization, strong It is necessary to use an alkaline neutralizing agent. Specifically, examples of the strong alkaline neutralizing agent include slaked lime slurry and the like industrially. Although strong alkaline caustic soda can be used as a neutralizing agent, it is disadvantageous in terms of cost.

  However, when a slaked lime slurry is used alone as a neutralizing agent and added, the degree of influence on the finished cost is large. Therefore, as a neutralizing agent, a portion of the slaked lime slurry used is replaced with an inexpensive calcium carbonate slurry, and the two types of neutralizing agents are used to perform stepwise neutralization treatment with adjusted end point pH. Has been proposed (for example, Patent Document 1).

  However, among the two types of neutralizers, slaked lime slurry, which is a strong alkaline neutralizer, is generally packed in a flexible container or the like, and when the amount of use increases, complicated pretreatment and pretreatment equipment Is required. Also, even if slaked lime slurry is advantageous in terms of cost compared to other neutralizing agents, the amount of poor liquid generated from the sulfidation process will increase and the amount of neutralizing agent used will be enormous. There is a problem that the degree of influence on is increased.

JP2013-256691A

  The present invention has been proposed in view of such circumstances, and in a neutralization treatment for neutralizing and removing the metal ions from a sulfuric acid acidic solution containing one or more metals of iron, magnesium, and manganese, An object of the present invention is to provide a method capable of effectively reducing the amount of slaked lime slurry, which is a high-cost strong alkaline neutralizer, and performing an efficient neutralization treatment.

  This inventor repeated earnest examination in order to solve the subject mentioned above. As a result, a portion of the slaked lime slurry is replaced with a calcium carbonate slurry, and a two-step neutralization treatment is performed using these two types of neutralizing agents. By using a slaked lime slurry adjusted to a specific range, the amount of slaked lime slurry that is a high-cost neutralizing agent can be reduced more effectively, and an efficient neutralization treatment can be performed. The present inventors have found that this can be done and have completed the present invention.

  (1) A first invention of the present invention is a neutralization treatment method for neutralizing and removing ions of a metal from a sulfuric acid acidic solution containing at least one of iron, magnesium, and manganese. A first neutralization treatment step of applying a neutralization treatment to a sulfuric acid acidic solution using calcium carbonate slurry as a first neutralizing agent and having a pH range of 5.0 to 6.0 as an end point; The solution obtained through the neutralization treatment step is neutralized using slaked lime slurry as a second neutralizing agent, and a precipitate containing the metal contained in the sulfuric acid acidic solution and ions of the metal are present. A slaked lime slurry having a solid concentration (% Solid) range of 10% to 18% in the second neutralization treatment step. It is a neutralization processing method which performs the neutralization process using.

  (2) The second invention of the present invention is the neutralization treatment method according to the first invention, wherein in the first neutralization treatment step, the end point pH is in the range of 5.0 to 5.6. .

  (3) According to a third aspect of the present invention, in the first or second aspect, in the second neutralization treatment step, the neutralization treatment is performed with the pH range of 8.5 to 9.5 as an end point. It is a sum processing method.

  (4) According to a fourth aspect of the present invention, in any one of the first to third aspects, the sulfuric acid acidic solution is a leaching process in which sulfuric acid is added from nickel oxide ore under high temperature and high pressure to leach nickel. This is a neutralization treatment method, which is a poor solution obtained by adding a sulfurizing agent to the solution obtained through the sulfurization treatment.

  According to the present invention, in the neutralization treatment for neutralizing and removing ions of a metal from a sulfuric acid acidic solution containing at least one of iron, magnesium, and manganese, it is a costly strong alkaline neutralizer. It is possible to provide a method capable of effectively reducing the amount of slaked lime slurry used and performing an efficient neutralization treatment.

It is process drawing which shows the flow of the hydrometallurgical process of nickel oxide ore. It is process drawing of the neutralization processing method. It is a graph which shows the relationship of the loss amount of the slaked lime slurry used as a neutralizing agent with respect to pH of the final liquid in the neutralization process in a 2nd neutralization process process.

Hereinafter, specific embodiments of the present invention (hereinafter referred to as “present embodiments”) will be described in detail in the following order. 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 neutralizes and removes ions of these metals from a sulfuric acid acidic solution containing at least one of iron, magnesium, and manganese.

  Specifically, this neutralization treatment method uses the calcium carbonate slurry as the first neutralizing agent and neutralizes the sulfuric acid acidic solution described above with the pH range of 5.0 to 6.0 as the end point. The solution obtained through the first neutralization treatment step and the first neutralization treatment step is neutralized using slaked lime slurry as a second neutralizing agent, and the metal contained in the sulfuric acid acidic solution is added. And a second neutralization treatment step for obtaining a precipitate to be contained and a neutralized final solution from which the metal ions have been removed.

  Thus, in the neutralization treatment method according to the present invention, stepwise neutralization treatment is performed using two kinds of neutralizing agents, with the predetermined pH range as the 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, since a neutralization treatment using an inexpensive calcium carbonate slurry is first performed as the first neutralization treatment, a high-cost slaked lime slurry conventionally used as a neutralizing agent The amount of use can be reduced.

  In addition, in the neutralization treatment method according to the present invention, slaked lime slurry is used as a neutralizing agent in the second-stage neutralization treatment, but the solid concentration (% Solid) range is used in a specific range. It is a feature. According to such a method, it is possible to further reduce the amount of slaked lime slurry that is a strong alkaline neutralizing agent of the two types of neutralizing agents to be used, and to make impurities more efficiently. A neutralization treatment for neutralizing and removing metal elements can be performed. Thereby, even if it is a case where the quantity of the sulfuric acid acidic solution which should be processed increases, the excessive increase in processing cost can be prevented and an efficient process can be performed.

  Here, as the sulfuric acid acidic solution containing one or more metals of iron, magnesium, and manganese, for example, a solution obtained through a leaching treatment in which nickel is leached by adding sulfuric acid from nickel oxide ore under high temperature and high pressure. On the other hand, the poor liquid obtained by adding a sulfurizing agent and performing a sulfuration process can be mentioned. In addition, any one or more metal of iron, magnesium, and manganese is the metal which remained in the poor liquid through the hydrometallurgy process to nickel oxide ore.

  Below, the aspect using the poor liquid obtained through the hydrometallurgical process of such a nickel oxide ore is mentioned as an example, and it demonstrates more concretely as a sulfuric acid acidic solution.

≪2. Nickel oxide ore hydrometallurgical process »
The outline of the hydrometallurgical process of nickel oxide ore will be described. Here, a hydrometallurgical process using a high-pressure acid leaching method in which leaching is performed using sulfuric acid under high temperature and high pressure will be described as a specific example.

  FIG. 1 is a process diagram showing the flow of a hydrometallurgical process by high pressure acid leaching of nickel oxide ore. The nickel oxide ore hydrometallurgical process includes a leaching step S1 for leaching nickel from a nickel oxide ore slurry, a solid-liquid separation step S2 for separating the obtained leaching slurry into a leaching solution and a leaching residue, and a leaching solution. Neutralization step S3 for neutralization and separation into a mother liquor for recovering nickel and neutralized starch, and a sulfide and poor solution containing nickel and cobalt by adding a sulfiding agent to the sulfuric acid solution that is the mother liquor and subjecting it to sulfidation And sulfiding step S4 to obtain

(1) Leaching step In the leaching step S1, sulfuric acid is added to the nickel oxide ore slurry (ore slurry), and the mixture is stirred at a high temperature and high pressure to perform a leaching treatment that forms a leaching slurry composed of a leaching solution and a leaching residue. . In the leaching process in the leaching step S1, for example, a high-temperature pressurized container (autoclave) is used.

  Here, as the raw material nickel oxide ore, so-called laterite ores such as limonite ore and saprolite ore are mainly mentioned. The nickel content of the laterite ore is usually 0.8% to 2.5% by mass, and is contained as a hydroxide or a siliceous clay (magnesium silicate) mineral. Moreover, although iron content is 10 mass%-50 mass%, and it is a form of a trivalent hydroxide (goethite), a part of bivalent iron is contained in a siliceous clay soil. .

  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)

  Although the density | concentration of the ore slurry used for a leaching process is not specifically limited, It is preferable to prepare so that the slurry density | concentration of a leaching slurry may be about 15 mass%-45 mass%. In addition, as the amount of sulfuric acid added in the leaching treatment, an excessive amount is used so that iron in the ore is leached. For example, it is about 300 kg to 400 kg per ton of ore. In addition, when the addition amount of sulfuric acid 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 subjected to multistage cleaning to separate into a leaching solution containing nickel and cobalt and a leaching residue.

  As the multistage cleaning method in the solid-liquid separation step S2, it is preferable to use a continuous alternating current cleaning method in which a countercurrent is brought into contact with a cleaning liquid not containing nickel. Thereby, 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, calcium carbonate is added so that the pH of the leachate is 4.0 or less, preferably 2.8 to 3.0, while suppressing the oxidation of the separated leachate. Then, a mother liquor for recovering nickel and a slurry of neutralized starch containing trivalent iron are formed. In the neutralization step S3, the leaching solution is neutralized in this way to neutralize excess acid used in the leaching treatment, and to remove trivalent iron ions, aluminum ions, etc. remaining in the solution. Remove. When the pH of the leachate exceeds 4.0, the generation of nickel hydroxide increases.

  The slurry of neutralized starch 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.

(4) Sulfurization step In the sulfidation step S4, a sulfurization agent such as hydrogen sulfide gas is added to the sulfuric acid solution, which is the mother liquor for nickel recovery obtained in the neutralization step S3, to cause a sulfidation reaction, and contains nickel and cobalt. It produces sulfide and poor liquid. In addition, when zinc is contained in the mother liquor, a process of selectively separating zinc as a sulfide can be performed prior to forming a sulfide of nickel and cobalt by a sulfidation reaction.

  As described above, the mother liquor for nickel recovery, which is a target for the sulfidation treatment, is a sulfuric acid solution containing nickel and cobalt based on the leachate obtained by leaching nickel oxide ore. Specifically, for example, the pH is 2.7 to 3.3, the nickel concentration is 2 g / L to 5 g / L, and the cobalt concentration is 0.1 g / L to 1.0 g / L. Moreover, it is the sulfuric acid solution which contains any one or more of iron, magnesium, and manganese as an impurity metal component as an impurity component, for example.

  Impurity metal components vary greatly depending on the oxidation-reduction potential (ORP) in the leaching process, the operating conditions of the autoclave, and the ore quality. Generally, iron, magnesium, manganese, and other impurity metal elements are several g / It is included at a rate of about L.

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

  Thus, in the sulfiding step S4, a sulfide containing nickel and cobalt with a low impurity content 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 treatment is settled and separated using a sedimentation device such as thickener, so that the sulfide as a precipitate is separated and recovered from the bottom of the thickener, and the aqueous solution component overflows. And recovered as a poor solution.

≪3. Neutralization method >>
As described above, the poor liquid obtained through the sulfidation step S4 in the nickel oxide ore hydrometallurgical process contains impurities metal ions including 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 hydrometallurgical process, it is preferable to carry out a neutralization treatment in order to reduce the impurity component as much as possible.

  Conventionally, in this neutralization treatment for the poor solution, a highly alkaline neutralizing agent such as slaked lime slurry has been used 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 the neutralizing agent such as slaked lime slurry, which is relatively advantageous in terms of cost with respect to other neutralizing agents, is used when the amount of poor liquid to be processed increases, There is a problem that the influence on the cost is large.

  Therefore, in the neutralization method according to the present embodiment, a portion of the slaked lime slurry used as a neutralizing agent is replaced with a calcium carbonate slurry that is an inexpensive neutralizing agent, and the two types of neutralizing agents are used. Step-by-step neutralization.

  Specifically, as shown in the process diagram of FIG. 2, this neutralization treatment method uses calcium carbonate slurry as a first neutralizing agent for the poor solution (sulfuric acid solution) and ends the predetermined pH range. The neutralization process using the slaked lime slurry as the second neutralizing agent is performed on the solution obtained in the first neutralization process S11 and the first neutralization process S11. And a second neutralization treatment step S12 for generating a precipitate containing an impurity metal 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. As described above, the poor solution is a sulfuric acid solution obtained by subjecting nickel oxide ore to a hydrometallurgical process.

  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 neutralization treatment in the first stage, it is used in the neutralization treatment in the second stage described later. The usage-amount of the slaked lime slurry which is an alkaline neutralizer can be reduced.

  In the first neutralization treatment in the stepwise neutralization treatment, the neutralization treatment is performed by adjusting a specific pH range as the end point of the neutralization reaction. Specifically, in the first neutralization treatment step S <b> 11, 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 5.0 to 5.6.

  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 By performing this, the amount of slaked lime slurry used as a neutralizing agent can be effectively reduced. Further, by appropriately adjusting the pH at the end point to the above-described range, it is possible to reduce the total amount of neutralizing agent used in the entire neutralization treatment and perform an efficient neutralization treatment with reduced processing costs. .

  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. Further, even when the end point pH is adjusted to exceed 6.0 to increase the load of the first neutralization treatment, the amount of neutralizing agent used in the second neutralization treatment step S12 is hardly changed. For this reason, the amount of neutralizing agent used in the entire neutralization treatment is increased, which is economically inefficient.

  Further, preferably, the neutralization treatment of the first stage is performed with the end point in the range of pH 5.0 to 5.6, so that the amount of neutralizing agent used in the first neutralization treatment and the second neutralization treatment are used. The use amount of the neutralizing agent 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.

  The pH of the solution can be measured using a known method, and the end point of the neutralization treatment can be determined 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 slaked lime slurry that is 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. The slaked lime slurry is a strong alkaline neutralizer and is relatively expensive.

  As described above, the neutralization treatment using the calcium carbonate slurry in the first neutralization treatment step S11 is performed with the predetermined pH range as the end point, so that the neutralizing agent used in the second neutralization treatment is used. The usage-amount of the slaked lime slurry which is can be reduced effectively.

  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 metals 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 at the end point exceeds 9.5, the precipitation of impurity metal does not proceed further, the load of neutralization treatment increases, the amount of slaked lime slurry used increases, and the economic efficiency deteriorates. It will be.

  More preferably, the neutralization treatment of the second stage is performed by setting the pH range of the end point to 8.9 to 9.1. Thereby, the usage-amount of a 2nd neutralizing agent can further be suppressed, and a more efficient neutralization process can be performed. The pH control in the second neutralization treatment step S12 can be performed in the same manner as the method performed in the neutralization treatment in the first neutralization treatment step S11.

  Here, as described above, although the amount of high-cost slaked lime slurry used can be reduced by performing the two-step neutralization treatment, the amount of slaked lime slurry used can be further reduced. desirable. Therefore, in the present embodiment, the slaked lime slurry used in the second neutralization treatment step S12 is characterized in that the solid concentration (% Solid) is in the range of 10% to 18%. .

  In this way, by adjusting the solid concentration of the slaked lime slurry used in the neutralization treatment in the second neutralization treatment step S12 and using a specific range as a neutralizing agent, the loss of the slaked lime slurry to be used The amount can be reduced. That is, since the slaked lime slurry can be used effectively while reducing the loss, the amount of use can be further reduced, and a more efficient treatment can be performed.

  Regarding the solid concentration (% Solid) of the slaked lime slurry, if the solid concentration is less than 10%, the volume of the slurry necessary for the neutralization treatment increases and the residence time required for the reaction decreases. That is, the neutralization processing time per unit volume is reduced. And when residence time falls in this way, the amount of slaked lime slurry used as an unreacted loss will increase. On the other hand, if the solid concentration exceeds 18%, the diffusibility of the neutralizing agent deteriorates in the neutralization reaction tank in which the neutralization treatment is performed, thereby requiring an excessive neutralizing agent and the processing cost. Will increase.

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

<< 4. Examples >>
Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

[Example]
It consists of a sulfuric acid solution containing nickel and cobalt and iron, magnesium, manganese, and other impurity metals recovered through the leaching step, solid-liquid separation step, and neutralization step in the hydrometallurgical process of nickel oxide ore. The mother liquor was subjected to a sulfiding step in which hydrogen sulfide gas was blown to form a sulfide containing nickel and cobalt. Then, the neutralization process which neutralizes and removes the impurity metal ion contained in the poor liquid with respect to the poor liquid which is the sulfuric acid acidic solution discharged | emitted from the sulfurization process was performed.

(First neutralization treatment)
Specifically, in the neutralization treatment, first, the poor solution is charged into the neutralization reaction tank, and the density is 1.2 g / cm as the first neutralizer with respect to the poor solution 1 m ³ (pH 1.7). ³ calcium carbonate slurry was added to perform a first neutralization treatment. In the first neutralization treatment, neutralization was performed until the end-point pH was 5.5.

(Second neutralization treatment)
Subsequently, slaked lime slurry having a slurry solid concentration of 12% to 15% as a second neutralizing agent was added to the solution after the first neutralization treatment to perform a second neutralization treatment. In the second neutralization treatment, neutralization was performed until the end point pH reached 9.00 to 9.10, and the residence time was 100 minutes. And the addition amount of the neutralizing agent (slaked lime slurry) used by such a 2nd neutralization process was calculated | required.

[Comparative Example 1]
In Comparative Example 1, neutralization treatment was performed in the same manner as in Example 1 except that a slaked lime slurry having a slurry solid concentration of 19% to 21% was added as the second neutralizing agent. The amount of slaked lime slurry added was determined. In addition, in the 2nd neutralization process in the comparative example 1, it was made to neutralize until end point pH was set to 8.94-9.10.

[result]
Table 1 below shows the end point pH conditions of the examples and comparative examples, and the calculation results of the loss amount of the slaked lime slurry at that time. As described above, slaked lime slurry having a solid concentration of 12% to 15% was used in Examples, and slaked lime slurry having a solid concentration of 19% to 21% was used in Comparative Examples.

Here, the loss amount of the slaked lime slurry is necessary in the second neutralization treatment per Ni 1t after adjusting the pH to 5.1 to 5.4 by adding the calcium carbonate slurry in the first neutralization treatment. The amount of slaked lime slurry added excessively until reaching a certain pH (end point pH) was calculated, and the loss amount was calculated by the following formula.
Slaked lime slurry loss =
(Slaked lime consumption-Amount of slaked lime required to precipitate the metal) / Ni treatment amount

  In the above calculation formula, (1) “slaked lime consumption” refers to the amount of slaked lime actually used in the reaction, and (2) “amount of slaked lime necessary to precipitate the metal” The amount of slaked lime theoretically required for the reaction, calculated based on the analytical values before and after the reaction. Therefore, the difference ((1)-(2)) is the amount of slaked lime that does not contribute to the reaction. The “Ni treatment amount” refers to the Ni recovery amount obtained through a hydrometallurgical process for recovering nickel. The neutralization process in this embodiment is a process for the poor liquid discharged from the hydrometallurgical process. Therefore, by calculating the amount of slaked lime loss with respect to the Ni treatment amount, The efficiency of the neutralization treatment can be determined.

  FIG. 3 is a graph showing the relationship between the measurement results of the amount of slaked lime slurry per Nit with respect to the condition of the end point pH in the second neutralization treatment in Examples and Comparative Examples.

  As shown in Table 1 and FIG. 3, according to the operation of the example, compared with the comparative example using the slaked lime slurry having a relatively high solid concentration, the amount of slaked lime slurry lost when adjusting to the same end point pH. Was able to be reduced. In addition, the significant difference was recognized as a result of having test | inspected the difference about the measurement result of the loss amount in the Example shown in Table 1, and a comparative example.

Claims (4)

A neutralization treatment method for neutralizing and removing ions of a metal from a sulfuric acid acidic solution containing one or more metals of iron, magnesium, and manganese,
A first neutralization treatment step of applying a neutralization treatment using calcium carbonate slurry as a first neutralizing agent with respect to the sulfuric acid acidic solution, with a pH range of 5.0 to 6.0 as an end point;
The solution obtained through the first neutralization treatment step is neutralized using a slaked lime slurry as a second neutralizing agent, and a precipitate containing a metal contained in the sulfuric acid acidic solution, A second neutralization treatment step for obtaining a neutralized final solution from which metal ions have been removed,
In the second neutralization treatment step, a neutralization treatment method in which neutralization treatment is performed using a slaked lime slurry having a solid concentration (% Solid) range of 10% to 18%. The neutralization treatment method according to claim 1, wherein, in the first neutralization treatment step, the pH at the end point is set in a range of 5.0 to 5.6. The neutralization treatment method according to claim 1 or 2, wherein in the second neutralization treatment step, the neutralization treatment is performed with a pH range of 8.5 to 9.5 as an end point. The sulfuric acid acidic solution is a poor liquid obtained by adding a sulfurizing agent to a solution obtained through leaching treatment by leaching nickel by adding sulfuric acid from nickel oxide ore under high temperature and high pressure. The neutralization processing method of any one of Claims 1 thru | or 3.

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