JP7087601B2 - Sulfide removal method and nickel oxide ore hydrometallurgy method - Google Patents

Description

The present invention is a method for removing a sulfurizing agent for removing a sulfurizing agent such as hydrogen sulfide in a post-sulfurized liquid obtained through a sulfurization treatment in a wet smelting process for nickel oxide ore, and a wet production of nickel oxide ore using the same. Regarding the smelting method.

As a hydrometallurgy method for nickel oxide ore (wet hydrometallurgy process for nickel oxide ore), there is a high-pressure acid leaching method using sulfuric acid. This method is advantageous in terms of energy and cost because it does not include a reduction and drying step and consists of a consistent wet step, unlike the dry smelting method which is a conventional general method for smelting nickel oxide ore. At the same time, it has an advantage that a sulfide containing nickel (hereinafter, also referred to as "nickel sulfide") having a nickel grade increased to about 50% by mass can be obtained.

The hydrometallurgical method for nickel oxide ore based on the high-pressure acid leaching method includes, for example, the following steps.
(A) Sulfide is added to a slurry of nickel oxide ore and leached under high temperature and high pressure, and the leaching residue slurry is solid-liquid separated from the obtained leaching slurry to obtain a leaching solution containing a metal element such as cobalt together with nickel. Leaching step and solid-liquid separation step (b) Neutralization step of adding a neutralizing agent to the leachate to obtain a neutralizing starch slurry containing an impurity element and a neutralizing final solution containing nickel (c) Neutralizing final solution On the other hand, a sulfurization step of obtaining a nickel sulfide and a post-sulfide liquid by sulfurizing with hydrogen sulfide gas (d) a wastewater treatment step of neutralizing the post-sulfide liquid after separation of nickel sulfide to make it harmless.

Hydrogen sulfide is dissolved in the post-sulfide liquid after separation of nickel sulfide. Therefore, in order to remove the hydrogen sulfide, a leachate obtained by solid-liquid separation of trivalent iron, for example, a leachate slurry as described in Patent Document 1, in the post-sulfide liquid after separation of nickel sulfide. With iron hydroxide (III) or hematite (iron oxide (III)) obtained by detoxifying the post-sulfidation liquid obtained by neutralizing and sulfurizing the wastewater in the wastewater treatment step (neutralization step). , With sulfuric acid. Thereby, hydrogen sulfide can be removed by reacting iron (III) hydroxide or iron (III) oxide with hydrogen sulfide dissolved in the post-sulfurized liquid. The reaction for removing hydrogen sulfide with iron (III) hydroxide is shown in the following formula (1). Further, the reaction for removing hydrogen sulfide by iron (III) oxide is shown in the following formulas (2) and (3).
Fe (OH) ₃ + 1 / 2H ₂ S + H ₂ SO ₄
→ FeSO ₄ + 1 / 2S ⁰ + 3H ₂ O (1)
Fe ₂ O ₃ + 3H ₂ SO ₄ → Fe ₂ (SO ₄ ) ₃ + 3H ₂ O (2)
Fe ₂ (SO ₄ ) ₃ + H ₂ S → 2 FeSO ₄ + H ₂ SO ₄ + S ⁰ (3)

When removing the dissolved hydrogen sulfide in the post-sulfidation liquid in this way, for example, as in Patent Document 2, the removal of the dissolved hydrogen sulfide gas is promoted by performing aeration at the same time as stirring in the aeration tank. Is common.

In the sulfurization step, in order to reduce the recovery loss of nickel, it is desirable to increase the amount of hydrogen sulfide gas added to increase the amount of nickel sulfide produced and reduce the nickel concentration of the post-sulfide solution. However, if the amount of hydrogen sulfide gas dissolved in the post-sulfurized liquid after the sulfide process increases by increasing the amount of hydrogen sulfide gas added, hydrogen sulfide cannot be completely removed and the concentration of hydrogen sulfide gas in the exhaust gas discharged to the outside of the system increases. The problem of rising occurs. Therefore, in order to reduce the recovery loss of nickel in the sulfurization step and to reduce the concentration of hydrogen sulfide gas in the exhaust gas, there is a demand for a method capable of effectively reducing hydrogen sulfide.

Japanese Unexamined Patent Publication No. 2004-089915 JP 2015-127053

The present invention has been made in view of such circumstances, and is a method for removing a sulfurizing agent, which is a method for removing a sulfurizing agent such as hydrogen sulfide from a post-sulfurized liquid generated in a wet smelting process of nickel oxide ore. It is an object of the present invention to provide a method for removing a sulfurizing agent capable of effectively reducing the sulfurizing agent and a method for wet smelting of nickel oxide ore using the same.

The present inventors have made extensive studies to solve the above-mentioned problems. As a result, when removing the sulfurizing agent such as dissolved hydrogen sulfide in the post-sulfurization liquid, the Fe ³⁺ concentration of the leachate slurry obtained by acid leaching is set to 2.9 g / L or more in the wet smelting process of nickel oxide ore. The leachate slurry is neutralized to generate iron (III) hydroxide to obtain a leachate slurry containing iron (III) hydroxide, and the leachate slurry containing the iron (III) hydroxide is subjected to solid-liquid separation treatment. It was found that the sulfurizing agent contained in the post-sulfidation liquid can be effectively reduced by immobilizing a sulfurizing agent such as hydrogen sulfide using the leachate residue containing iron (III) hydroxide thus obtained. After further studies, the present invention was completed. That is, the present invention provides the following.

(1) In the first invention of the present invention, a leachate slurry obtained by leaching nickel oxide ore with sulfuric acid under high temperature and high pressure is solid-liquid separated to obtain a leachate containing nickel and a leachate residue, and the leachate is obtained. On the other hand, in a wet smelting process in which a sulfide treatment is performed with a sulfide agent to produce nickel sulfide and a post-sulfurized liquid, the sulfide agent dissolved in the post-sulfurized liquid obtained by separating the nickel sulfide is used. In the method for removing the sulfide to be removed, in the acid leaching, the Fe ³⁺ concentration in the obtained leached slurry is 2.9 g / L or more, and in the solid-liquid separation, the leached slurry is neutralized. After iron (III) hydroxide is generated to obtain a leachate slurry containing iron (III) hydroxide, the leachate slurry containing iron (III) hydroxide is subjected to solid-liquid separation treatment to hydroxylate the leachate containing nickel. A leaching residue containing iron (III) is obtained, and the sulfide agent contained in the post-sulfurized liquid is immobilized and removed by adding the leaching residue containing the iron (III) hydroxide to the post-sulfurized liquid. It is a method of removing the sulfide agent.

(2) In the second invention of the present invention, the leaching residue containing the iron hydroxide (III) obtained by solid-liquid separation with respect to the leaching slurry is subjected to the sulphurized liquid in the wet smelting process. The sulphurization according to the first invention, which is subjected to wastewater treatment to be detoxified by subjecting to neutralization treatment, and a leachate residue containing the iron (III) hydroxide after the wastewater treatment is added to the post-sulfurized liquid. It is a method of removing the agent.

(3) In the third aspect of the present invention, in the neutralization treatment for the leached slurry, the removal of the sulfurizing agent according to the first or second invention, which makes the pH of the leached slurry 2.5 to 3.2. The method.

(4) The fourth invention of the present invention is the sulfurization according to any one of the first to third inventions, wherein sulfuric acid is added to the post-sulfidation liquid together with the leachate residue containing the iron (III) hydroxide. It is a method of removing the agent.

(5) In the fifth aspect of the present invention, the post-sulfuric acid solution has a nickel ion concentration of 0.02 to 0.10 g / L and contains at least one selected from iron, manganese, magnesium, aluminum and chromium. The method for removing a sulfide agent according to any one of the first to fourth inventions, which is an acidic solution containing sulfuric acid.

(6) The sixth invention of the present invention is one of the first to fifth inventions in which the leachate residue containing the iron (III) hydroxide is added to the post-sulfurized liquid and aeration is performed. The method for removing a sulfide agent according to the above.

(7) The seventh invention of the present invention is a leaching step of leaching nickel oxide ore with sulfuric acid under high temperature and high pressure to obtain a leaching slurry, and a solid-liquid separation of the leaching slurry obtained in the leaching step to nickel. A solid-liquid separation step for obtaining a leachate containing a leachate and a leachate residue, and a neutralized final liquid containing nickel and a neutralized starch containing an impurity element by adding a neutralizing agent to the leachate obtained in the solid-liquid separation step. A sulfide step of obtaining a nickel sulfide and a post-sulfurized liquid by subjecting the neutralized final solution obtained in the neutralization step to a sulfide treatment with a sulfide agent, and the nickel sulfide. It is a wet smelting method for nickel oxide ore having a sulfide agent removing step of fixing and removing the sulfide agent contained in the post-sulfurized liquid obtained by separation, and the solid-liquid separation step is the leaching step. The leached slurry obtained in the above step is subjected to a neutralization treatment to generate iron hydroxide (III) to obtain a leached slurry containing iron (III) hydroxide, and the pre-neutralization step is obtained. The leaching slurry containing the iron (III) hydroxide is subjected to solid-liquid separation treatment to obtain a leaching solution and a leaching residue containing iron (III) hydroxide. In the leaching step, the leaching slurry is contained. Fe ³⁺ concentration of 2.9 g / L or more, and in the sulfide removing step, the post-sulfurized liquid obtained by separating the sulfide of nickel is leached containing the iron (III) hydroxide. It is a wet smelting method of nickel oxide ore that immobilizes and removes a sulfide agent contained in the post-sulfurization liquid by adding a residue.

According to the method for removing a sulfurizing agent of the present invention, a sulfurizing agent such as hydrogen sulfide can be effectively reduced from the post-sulfurized liquid generated in the wet smelting process of nickel oxide ore, and hydrogen sulfide or the like can be effectively reduced from the post-sulfurized liquid. The sulfurizing agent can be sufficiently removed.

As described above, according to the present invention, since the sulfurizing agent in the post-sulfidation liquid can be effectively reduced, a large amount of the sulfurizing agent for recovering nickel can be added. Therefore, the present invention has extremely high industrial value because it can improve the environment and safety by reducing nickel loss and suppressing the occurrence of sulfide removal defects in the hydrometallurgical process of nickel oxide ore.

It is a process drawing which shows an example of the flow of the wet smelting method of nickel oxide ore in this embodiment. It is a figure which shows the relationship between Fe ³⁺ concentration and free sulfuric acid concentration in a leachate slurry. It is a figure which shows the relationship between the Fe ³⁺ concentration in a leaching slurry and the hydrogen sulfide concentration in an exhaust gas.

Hereinafter, a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention. Further, in the present specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

≪1. Overview ≫
In the method for removing the sulfide agent according to the present embodiment, the leachate slurry obtained by acid leaching nickel oxide ore with sulfuric acid under high temperature and high pressure is solid-liquid separated to obtain a leachate containing nickel and a leachate residue, and the leachate is obtained. On the other hand, a wet smelting process of nickel oxide ore to obtain nickel sulfide by subjecting it to sulfurization treatment with a sulfurizing agent to generate a sulfur sulfide of nickel and a post-sulfurization liquid (hereinafter, also simply referred to as "wet smelting process"). ) Is a method for removing a sulfurizing agent such as hydrogen sulfide dissolved from the after-sulfurized liquid. In the present specification, the "sulfurizing agent" to be removed includes hydrogen sulfide generated from the sulfurizing agent in addition to the sulfurizing agent itself such as hydrogen sulfide, sodium sulfide, and sodium hydride sulfide used in the sulfurizing step. .. Further, the nickel sulfide refers to a sulfide containing nickel, and also includes a mixed sulfide of nickel and another metal such as cobalt.

Specifically, the method for removing the sulfide agent according to the present embodiment is to set the Fe ³⁺ concentration of the leached slurry obtained by acid leaching to 2.9 g / L or more in the wet smelting process and neutralize the leached slurry. Treatment is performed to generate iron (III) hydroxide to obtain a leachate slurry containing iron (III) hydroxide, and the leachate slurry containing the iron (III) hydroxide is subjected to solid-liquid separation treatment to obtain hydroxylation. The leachate residue containing iron (III) is used as a trivalent iron ion source and added to the post-sulfurized solution. As a result, as will be described in detail later, the sulfurizing agent such as hydrogen sulfide dissolved in the post-sulfurized liquid is fixed and removed (recovered) by the iron (III) hydroxide contained in the leachate residue. In addition, "fixing" here means converting a compound into a stable form, and in the method for removing a sulfurizing agent according to the present embodiment, a sulfurizing agent such as hydrogen sulfide dissolved in a post-sulfurized liquid is used. , It is converted into a stable form as elemental sulfur (S ⁰ ) by reaction with iron (III) hydroxide, and this elemental sulfur is precipitated and removed.

≪2. Wet smelting process of nickel oxide ore ≫
First, prior to a more specific explanation of the method for removing the sulfide ore, the wet smelting of nickel oxide ore is used with reference to FIG. 1, which is a process diagram showing the flow of the wet smelting method of nickel oxide ore in the present embodiment. The entire process will be described.

As shown in FIG. 1, this wet smelting process includes a leaching step S11 in which nickel oxide ore as a raw material is acid-leached under high temperature and high pressure to obtain a leaching slurry, and the leaching slurry is washed in multiple stages as necessary. A solid-liquid separation step S12 for obtaining a leachate containing nickel and a leachate residue, and a neutralization step S13 for obtaining a neutralized starch slurry containing impurities and a neutralizing final solution containing nickel by adding a neutralizing agent to the leachate. It also has a sulphurization step S14 in which a nickel sulfide and a post-sulfuric acid liquid are obtained by subjecting the neutralized final liquid to a sulphurization treatment with a sulphurizing agent. The present embodiment further includes a wastewater treatment step S20 for neutralizing the post-sulfidated liquid separated in the sulfurization step S14 to make it harmless.

In the method for removing a sulfurizing agent according to the present embodiment, the post-sulfurized liquid obtained by the hydrometallurgical process of nickel oxide ore is treated, and the sulfurizing agent dissolved in the post-sulfurized liquid is removed.

(1) Leaching Step The leaching step S11 is a step of leaching the nickel oxide ore as a raw material with sulfuric acid under high temperature and high pressure to obtain a leaching slurry. For example, using a high-temperature pressure vessel (autoclave) or the like, sulfuric acid is added to a slurry of nickel oxide ore, and the mixture is stirred while being pressurized at a temperature of 220 ° C to 280 ° C. A leachate slurry consisting of In this embodiment, which will be described in detail later, in the leaching step S11, the Fe ³⁺ concentration in the leaching slurry obtained by acid leaching is set to 2.9 g / L or more.

Here, examples of the nickel oxide ore 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 earth (magnesium silicate) mineral.

(2) Solid-Liquid Separation Step The solid-liquid separation step S12 is a step of solid-liquid separating the leachate slurry obtained in the leachation step S11 into a leachate containing a valuable metal such as nickel or cobalt and a leachate residue. In the present embodiment, which will be described in detail later, in the solid-liquid separation step S12, the leached slurry obtained in the leaching step S11 is subjected to neutralization treatment to generate iron (III) hydroxide to generate iron hydroxide (III). Pre-neutralization step S121 to obtain leachate slurry containing III) and leachate slurry containing iron hydroxide (III) obtained in pre-neutralization step S121 are solid-liquid separated to separate leachate and iron (III) hydroxide. It has a separation step S122 to obtain a leachate residue containing.

In the pre-neutralization step S121, a neutralizing agent is added to the leachate slurry to perform a neutralization treatment for raising the pH (for example, making the pH 2.5 to 3.2). As a result, excess sulfuric acid (hereinafter, also referred to as “free sulfuric acid”) contained in the leached slurry is neutralized, and a part or all of Fe ³⁺ in the leached slurry becomes iron (III) hydroxide.

As the neutralizing agent in the preliminary neutralization step S121, conventionally known ones can be used, and examples thereof include basic compounds such as slaked lime (calcium hydroxide), calcium carbonate, and sodium hydroxide.

In the separation step S122, for example, after mixing the leached slurry after the preliminary neutralization step S121 with the cleaning liquid, a solid-liquid separation process is performed by a solid-liquid separation facility such as a thickener using a flocculant supplied from a coagulant supply facility or the like. To give. Specifically, first, the leachate slurry is diluted with a washing liquid, and then the leachate residue in the leachate slurry is concentrated as a sediment of thickener. The cleaning liquid for cleaning the leachate slurry is not particularly limited, but for example, a post-sulfurization liquid (post-treatment sulfurization liquid) after the sulfurizing agent removing step S30 in the subsequent stage can be used. The leachate residue obtained in the solid-liquid separation step S12 contains iron (III) hydroxide, iron (III) oxide, and iron (III) sulfate as iron compounds.

The leachate separated in the separation step S122 is transferred to the neutralization step S13, while the leachate residue is recovered from the bottom of the thickener. Since the leaching residue may contain a part of valuable metals such as nickel and cobalt, the liquid containing the valuable metals such as nickel and cobalt obtained by washing the leaching residue is also transferred to the neutralization step S13. You may try to do it.

(2) Neutralization Step The neutralization step S13 is a step of adding a neutralizing agent to the leachate obtained in the solid-liquid separation step S12 to obtain a neutralized starch slurry containing impurities and a neutralized final liquid containing nickel. Is. A neutralizing agent is added to the leachate obtained in the solid-liquid separation step S12 to adjust the pH, and a neutralized starch slurry containing an impurity element and a neutralized final liquid are obtained. By the neutralization treatment in this neutralization step S13, valuable metals such as nickel and cobalt are contained in the neutralization final solution, and most of the iron becomes a neutralized starch slurry. A coagulant may be added to accelerate the settling rate of the neutralized slurry.

As the neutralizing agent, conventionally known ones can be used, and examples thereof include slaked lime (calcium hydroxide), calcium carbonate, sodium hydroxide and the like.

In the neutralization treatment in the neutralization step S13, it is preferable to adjust the pH to the range of 1 to 4, and more preferably to the range of 2.5 to 3.5 while suppressing the oxidation of the leachate. If the pH is less than 1, neutralization may be insufficient and the neutralized starch slurry and the neutralized final solution may not be separated, and if the pH is less than 2.5, the subsequent sulfide step S14 There is a possibility that the sulfide reaction does not proceed in the dezincification step and the nickel recovery step. On the other hand, when the pH exceeds 4, not only impurities such as aluminum but also valuable metals such as nickel and cobalt may be contained in the neutralized starch slurry. When the neutralization slurry obtained in the neutralization step S13 contains a valuable metal such as nickel or cobalt, the neutralization slurry may be supplied to the solid-liquid separation step S12.

(3) Sulfurization Step The sulfurization step S14 is a step of subjecting the neutralization final liquid obtained in the neutralization step S13 to a sulfurization treatment with a sulfurizing agent to obtain nickel sulfide and a post-sulfide liquid. By the sulfurization treatment in this sulfurization step S14, nickel, cobalt, zinc and the like become sulfurized, and the others are contained in the post-sulfurized liquid.

Specifically, in the sulfurization step S14, a sulfurizing agent is added to the obtained neutralized final liquid to cause a sulfurization reaction in which nickel or cobalt contained in the neutralized final liquid is formed into a sulfide form. As a result, nickel sulfide having a small amount of impurity components and a post-sulfurization liquid in which the nickel concentration is stabilized at a low level are produced. When zinc is contained in the neutralization final solution, zinc can be selectively separated as sulfide by using a sulfide agent prior to adding a sulfide agent to generate nickel sulfide. (Dezincification process). That is, a dezincination step of forming a zinc sulfide by adding a sulfide agent to the neutralization final solution obtained in the neutralization step S13 and separating the zinc sulfide to obtain a nickel-containing mother liquor for recovering nickel. The sulfurization step S14 may include a nickel recovery step of forming a nickel sulfide by adding a sulfurizing agent to the nickel recovery mother liquor.

As the sulfurizing agent, for example, hydrogen sulfide, sodium sulfide, sodium sulfide and the like can be used, and among them, hydrogen sulfide gas is particularly preferable in terms of ease of handling and cost.

In this sulfurization treatment, the nickel sulfide slurry is settled and separated using a sedimentation separation device such as a thickener to separate and recover the sulfide from the bottom of the thickener, while the after-sulfidation liquid, which is an aqueous solution component, overflows and recovers. do.

In the method for removing a sulfurizing agent according to the present embodiment, the post-sulfidation liquid obtained by the sulfurization treatment in the sulfurization step S14, that is, the post-sulfurization obtained by subjecting the slurry after the sulfurization treatment to a solid-liquid separation treatment. The liquid is treated. Since the sulfurizing agent removing method according to the present embodiment can effectively reduce the sulfurizing agent as shown in Examples and the like, the amount of the sulfurizing agent added in the sulfurizing step S14 in the previous stage can be increased, and nickel can be used. Since sulfide can be sufficiently produced, the recovery loss of nickel can be reduced.

(4) Wastewater treatment process (neutralization treatment process)
In the wastewater treatment step S20, the post-sulfurized liquid produced in the sulphurizing step S14, that is, the post-sulfurized liquid containing impurity elements such as iron, magnesium and manganese, is neutralized to adjust to a predetermined pH range that satisfies the discharge standard. Wastewater is treated to make it harmless. As a result, components such as iron, magnesium, and manganese are removed.

In the present embodiment, the post-sulfidation liquid from which the dissolved sulfurizing agent such as hydrogen sulfide has been removed is discharged through the sulfurizing agent removing step S30, which is a treatment for removing the sulfurizing agent from the post-sulfurizing liquid, which will be described in detail later. Wastewater treatment is performed in the treatment step S20.

The method of detoxifying by neutralization treatment in the wastewater treatment step S20, that is, the method of adjusting pH is not particularly limited, but for example, neutralization of calcium carbonate (limestone) slurry, calcium hydroxide (slaked lime) slurry, sodium hydroxide and the like. It can be adjusted to a predetermined range by adding an agent.

Further, in the neutralization treatment in the wastewater treatment step S20, a first-stage neutralization treatment using limestone as a neutralizing agent (first step) and a second-stage neutralization treatment using slaked lime as a neutralizing agent. A stepwise process consisting of (second step) can be performed. By performing the stepwise neutralization treatment in this way, an efficient and effective neutralization treatment can be performed.

Specifically, in the first step, the after-sulfurized liquid recovered in the sulfurizing agent removing step S30 is charged into a neutralization treatment tank, and a limestone slurry is added to perform a stirring treatment. In this first step, the pH of the post-sulfidation liquid is adjusted to 5 to 6 by adding a limestone slurry. When the pH is 5 or less, aluminum is not completely removed, and the amount of slaked lime used for neutralization increases.

Next, in the second step, the slaked lime slurry is added to the solution subjected to the neutralization treatment in the first step by adding the limestone slurry, and the stirring treatment is performed. In this second step, the pH of the post-sulfidated liquid is raised to 8.5 to 9.5 by adding slaked lime slurry.

In the wastewater treatment step S20, by performing such a two-step neutralization treatment, a neutralization treatment residue (wastewater treatment starch) is generated and stored in a tailing dam (tailing residue). On the other hand, the solution after the wastewater treatment step S20 (the final liquid for wastewater treatment) satisfies the emission standard and is discharged to the outside of the system.

Here, in the neutralization treatment in the wastewater treatment step S20, slaked lime and limestone are used according to the amount of acid, sulfide, and impurity element ions such as iron ion, magnesium ion, and manganese ion remaining in the liquid after sulfurization. The amount of neutralizing agent such as is determined. Therefore, if the amount of acid, sulfurizing agent, and impurities remaining in the after-sulfurized liquid is large, the amount of neutralizing agent used is also large.

In this respect, in the present embodiment, prior to the wastewater treatment step S20, in the sulfurizing agent removing step S30, the sulfurized liquid obtained in the sulfurizing step S14 is sulfurized with hydrogen sulfide or the like dissolved in the sulfurized liquid. I try to remove the agent. Then, in the sulfide removing step S30, which will be described in detail later, the Fe ³⁺ concentration of the leached slurry obtained by acid leaching is set to 2.9 g / L or more, and the leached slurry is neutralized to obtain iron hydroxide (). III) is generated to obtain a leachate slurry containing iron hydroxide (III), and the leachate slurry containing the iron hydroxide (III) is subjected to solid-liquid separation treatment to obtain a leachate residue containing iron (III) hydroxide. Is used as a trivalent iron ion source for oxidatively immobilizing a sulfide agent such as hydrogen sulfide. Iron (III) hydroxide, like iron (III) oxide, needs to be dissolved in sulfuric acid in order to cause a reaction to remove the sulfide agent, but iron (III) hydroxide is more than iron (III) oxide. Is also easy to dissolve. Therefore, when iron (III) hydroxide is used for the removal reaction of the sulfurizing agent, the amount of sulfuric acid added in the sulfurizing agent removing step S30 is smaller than that when iron (III) oxide is used for the removing reaction of the sulfurizing agent. Can be done. Therefore, the post-sulfidation liquid having a low concentration of sulfuric acid or sulfurizing agent can be transferred to the wastewater treatment step S20. Further, as a trivalent iron ion source for removing the sulfide agent, only the neutralization treatment residue (wastewater treatment starch) obtained by the leachate through the neutralization step S13, the sulfide step S14, and the wastewater treatment step S20 was used. The post-neutralized liquid having a lower concentration of impurities such as magnesium, manganese, and aluminum can be transferred as compared with the case. Therefore, the post-sulfurized liquid having a low concentration of sulfuric acid and a sulfide agent and a low concentration of impurities such as iron, magnesium, manganese, and aluminum can be transferred to the wastewater treatment step S20. As a result, the amount of the neutralizing agent used in the wastewater treatment step S20 can be effectively reduced, and the nickel oxide ore treatment as a whole can be efficiently operated.

≪3. Detailed explanation of how to remove sulfurizing agent ≫
In the above-mentioned wet smelting process of nickel oxide ore, a sulfurizing agent such as hydrogen sulfide added to cause a sulfurization reaction is dissolved in the post-sulfide liquid produced through the sulfurization treatment in the sulfurization step S14. There is. In addition, when a sulfurizing agent other than hydrogen sulfide is used, hydrogen sulfide gas may be generated depending on the state of the solution, and unreacted hydrogen sulfide gas may be dissolved in the liquid after the reaction.

When a sulfurizing agent such as hydrogen sulfide remains in the after-sulfurized liquid as described above, it cannot be discharged to the outside of the system. In addition, if the after-sulfurized liquid is discharged to the solid-liquid separation step S12 or the wastewater treatment step S20, the odor of hydrogen sulfide may be generated around the equipment, which may cause environmental troubles, which is an environmental and safety problem. It becomes.

Therefore, in the present embodiment, the sulfurizing agent contained in the post-sulfidation liquid is immobilized as sulfur, that is, the dissolved sulfurizing agent such as hydrogen sulfide is immobilized as the solid sulfur S ⁰ form, and the sulfurized liquid is used. It is designed to be recovered and removed (sulfurizing agent removing step S30). In the following, a mode in which hydrogen sulfide remaining in the post-sulfidation liquid is removed in the sulfurizing agent removing step S30 when hydrogen sulfide gas is used as the sulfurizing agent in the sulfurizing step S14 will be described in more detail as an example.

Specifically, the sulfide removing step S30 contains iron (III) hydroxide obtained by subjecting an leached slurry having a Fe ³⁺ concentration in a specific range to a solid-liquid separation step S12 having a preliminary neutralization step S121 and a separation step S122. The leachate residue is used as a trivalent iron ion source. By adding the leachate residue containing iron (III) hydroxide to the post-sulfidation liquid containing hydrogen sulfide, hydrogen sulfide contained in the post-sulfidation liquid is fixed in the form of solid sulfur and removed.

The post-sulfuric acid solution obtained in the sulphurization step S14 has, for example, a nickel ion concentration of about 0.02 g / L to 0.10 g / L, and is sulfuric acid containing impurities such as iron, manganese, magnesium, aluminum, chromium, and lead. It is an acidic solution. The pH of the after sulfidation solution is, for example, about 1.5 to 2.0. Then, as described above, hydrogen sulfide used in the sulfurization treatment in the sulfurization step S14 is dissolved in the post-sulfidation liquid at a concentration of, for example, about 20 mg / L to 400 mg / L.

In the present embodiment, the Fe ³⁺ concentration of the leaching slurry obtained by acid leaching in the leaching step S11 is 2.9 g / L or more with respect to such a post-sulfurized liquid, and the leaching is performed in the preliminary neutralization step S121. The slurry is neutralized to generate iron (III) hydroxide to obtain an leached slurry containing iron (III) hydroxide, and the leached slurry containing the iron (III) hydroxide is solidified in the separation step S122. The leachate residue containing iron (III) hydroxide obtained by the liquid separation treatment is added. When iron (III) hydroxide generated from Fe ³⁺ contained in the leaching slurry and contained in the leaching residue is used as a trivalent iron ion source, the reaction of the following formula (4) occurs and is dissolved in the post-sulfidation liquid. Hydrogen sulfide is oxidized and immobilized as solid sulfur. As described above, by using the leaching residue containing iron (III) hydroxide as the trivalent iron ion source, hydrogen sulfide can be effectively decomposed and reduced. The iron (III) hydroxide contained in the leachate residue usually exists as iron oxide hydroxide (FeO (OH)) when it is contained as a solid, and is in a dissolved state (Fe ³⁺ ) when it is contained as a liquid. , OH- ⁾ . As shown in the following formula (4), in order to react iron (III) hydroxide with hydrogen sulfide, it is necessary to dissolve iron (III) hydroxide in sulfuric acid. Therefore, if the sulfuric acid contained in the post-sulfuric acid solution to be treated does not sufficiently dissolve iron (III) hydroxide, the leachate residue containing iron (III) hydroxide is added to the post-sulfuric acid solution, and the sulfuric acid is also sulphurized. Add to the after liquid.
Fe (OH) ₃ + 1 / 2H ₂ S + H ₂ SO ₄
→ FeSO ₄ + 1 / 2S ⁰ + 3H ₂ O (4)

In the present embodiment, the Fe ³⁺ concentration in the leaching slurry obtained by the acid leaching in the leaching step S11 is 2.9 g / L or more. This makes it possible to reduce hydrogen sulfide extremely effectively. According to the study of the present inventor, as shown in FIG. 3 described in Examples described later, there is a correlation between the Fe ³⁺ concentration in the leachate slurry and the sulfurizing agent removing effect in the sulfurizing agent removing step S30. Was found. This is due to the hydrogen sulfide removal reaction by iron (III) hydroxide represented by the formula (4) by using the leachate residue obtained from the leachate slurry whose Fe ³⁺ concentration is adjusted to the range of 2.9 g / L or more. It is presumed that the reactivity is significantly improved and hydrogen sulfide can be reduced extremely effectively.

The Fe ³⁺ concentration in the leaching slurry can be adjusted by controlling the amount of sulfuric acid added in the leaching process in the leaching step S11 to adjust the free sulfuric acid concentration in the leaching slurry. The free sulfuric acid is a surplus sulfuric acid, that is, a sulfuric acid other than sulfate ion that can be bonded to a metal element. The free sulfuric acid concentration is determined by neutralization titration with a sodium hydroxide solution.

FIG. 2 is a graph showing the relationship between the free sulfuric acid concentration in the leachate slurry and the Fe ³⁺ concentration in the leachate slurry. As shown in FIG. 2, it can be seen that the Fe ³⁺ concentration in the leachate slurry increases as the free sulfuric acid concentration increases. In the leaching treatment with sulfuric acid in the leaching step S11, iron contained in the raw material ore is immobilized as a leaching residue and contained in the leaching slurry, but unreacted sulfuric acid (free sulfuric acid) that did not contribute to the leaching treatment. As a result, the iron immobilized as the leaching residue is redissolved and becomes present in the leaching slurry in the form of Fe ³⁺ . Therefore, as shown in FIG. 2, a proportional relationship is established between the concentration of free sulfuric acid in the leachate slurry and the concentration of Fe ³⁺ . Therefore, the Fe ³⁺ concentration in the leaching slurry can be adjusted by controlling the amount of sulfuric acid added in the leaching process in the leaching step S11 to adjust the free sulfuric acid concentration in the leaching slurry.

The Fe ³⁺ concentration in the leachate slurry is preferably 3.6 g / L or less. In order to increase the Fe ³⁺ concentration in the leaching slurry, it is necessary to increase the amount of sulfuric acid added in the leaching step S11. Increasing the amount of sulfuric acid added increases the cost. Further, when the amount of sulfuric acid added is increased, the amount of the neutralizing agent added in the preliminary neutralization step S121 increases due to the increase in the free sulfuric acid concentration, so that the cost increases. Further, when the amount of sulfuric acid added is increased, fine particles are likely to be generated in the preliminary neutralization step S121, and solid-liquid separation failure occurs in the separation step S122. Therefore, the Fe ³⁺ concentration in the leachate slurry should not be too high, preferably 3.6 g / L or less.

In the present embodiment, as shown in FIG. 1, the leachate residue obtained in the solid-liquid separation step S12 is charged into the treatment in the wastewater treatment step S20 in the hydrometallurgical process, and the wastewater treatment step S20 is charged. To neutralize with. As described above, in the wastewater treatment step S20, a neutralization treatment is performed in which a neutralizing agent such as calcium hydroxide, calcium carbonate or sodium hydroxide is added to adjust the pH of the solution to about 8.5 to 9.5. Will be. Therefore, by charging the leachate residue into the treatment in the wastewater treatment step S20, iron (III) hydroxide can be produced from the iron compound such as iron (III) oxide contained in the leachate residue, and the leachate residue is contained. The amount of iron (III) hydroxide can be increased. In FIG. 1, the leaching residue containing iron (III) hydroxide added to the post-sulfurization solution is the wastewater treatment residue (neutralization treatment residue) obtained by subjecting the leaching residue to wastewater treatment (neutralization treatment). Both of the solutions may be used, or only the wastewater treatment residue (neutralization treatment residue) separated from the solution by solid-liquid separation after the wastewater treatment (neutralization treatment) may be used.

Here, in the wet smelting process, the leachate residue obtained by solid-liquid separation of the leachate slurry is the leachate obtained by solid-liquid separation of the leachate slurry in the neutralization step S13, the sulfide step S14, and the wastewater treatment step. There are less impurities such as magnesium, manganese, and aluminum than the neutralization treatment residue (wastewater treatment starch) obtained through S20. Therefore, as in the present embodiment, by using the leachate residue in the sulfurizing agent removing step S30, the hydrogen sulfide removing reaction by the iron (III) hydroxide represented by the above formula (4) is performed on magnesium, manganese, or aluminum. Since it is not easily inhibited by such elements, hydrogen sulfide can be effectively removed.

Further, the leachate residue obtained by solid-liquid separation of the leachate slurry is compared with the neutralization treatment residue (wastewater treatment starch) obtained by the leachate through the neutralization step S13, the sulfide step S14, and the wastewater treatment step S20. , Magnesium, manganese, aluminum and other impurities are few, and the iron content is high. Therefore, as in the present embodiment, by adding the leachate residue to the after-sulfurized liquid in the sulfurizing agent removing step S30, the amount of hydrogen sulfide removed is larger than the amount to be added, and hydrogen sulfide is effectively removed. be able to.

It is conceivable to use iron (III) sulfate as a trivalent iron ion source for immobilizing hydrogen sulfide, but it is disadvantageous in terms of cost such as capital investment and material purchase.

The pH of the post-sulfidation liquid (post-treatment liquid after sulfurization) after the sulfurizing agent removing step S30 is, for example, 1.5 to 2.0. The flow rate of the post-sulfurized liquid supplied to the sulfide removing step S30 and the flow rate of the post-sulfurized liquid after the sulphurizing agent removing step S30 to be discharged to the wastewater treatment step S20 are, for example, 500 to 700 m ³ / Hr. The supply flow rate of the leachate residue containing iron (III) hydroxide added to the post-sulfidation liquid is 40 to 50 m ³ / Hr.

Further, in the treatment in the sulfurizing agent removing step S30, it is preferable to add the leachate residue to the after-sulfurized liquid and perform aeration. That is, it is preferable that the reaction between iron (III) hydroxide contained in the leaching residue and hydrogen sulfide occurs in an aeration tank for aeration. For example, as described in Patent Document 2, a circle having a vertical cylindrical reaction vessel, a stirring blade provided in the reaction vessel, and a large number of outlets provided at the bottom of the reaction vessel. The post-sulfurized liquid is supplied to an aeration tank provided with an annular aeration tube, a leachate residue is added, and the aeration is performed at a ratio of 1.8 Nm ³ or more per 1 m ³ of the post-sulfurized liquid slurry while stirring. By such aeration, the oxidation of hydrogen sulfide dissolved in the post-sulfide liquid can be promoted, and hydrogen sulfide can be removed more efficiently.

The post-treatment sulfurized liquid from which hydrogen sulfide has been removed in the sulfurizing agent removing step S30 may be used as a cleaning liquid in the solid-liquid separation step S12.

As described above, according to the method for removing hydrogen sulfide according to the present embodiment, iron hydroxide (iron hydroxide) produced from a leachate slurry having a Fe ³⁺ concentration of 2.9 g / L or more as a trivalent iron ion source (as described above). By using the leachate residue containing III) as the main reaction body for the oxidation of hydrogen sulfide, hydrogen sulfide can be effectively reduced, so that hydrogen sulfide can be sufficiently removed.

As described above, according to the present invention, since the sulfurizing agent in the post-sulfidation liquid can be effectively reduced, a large amount of the sulfurizing agent for recovering nickel can be added. Therefore, the present invention has extremely high industrial value because it can improve the environment and safety by reducing nickel loss and suppressing the occurrence of sulfide removal defects in the hydrometallurgical process of nickel oxide ore.

Further, the post-sulfidation liquid after removing hydrogen sulfide is transferred to the wastewater treatment step S20 and subjected to wastewater treatment (neutralization treatment), but since hydrogen sulfide has been removed, after the treatment. In the wastewater treatment for the post-sulfidation liquid, the amount of the neutralizing agent used can be effectively reduced, and the entire nickel oxide ore treatment can be efficiently operated.

If a small amount of hydrogen sulfide remains in other steps such as the sulfurizing agent removing step S30 and the wastewater treatment step S20, or if a harmful gas that cannot be discharged to the outside of the system is generated, the abatement tower is used. After removing the harmful gas with a facility that removes harmful gas such as, it may be discharged into the atmosphere. Further, the post-sulfide liquid after treatment may be used as a cleaning liquid for treatment in the solid-liquid separation step S12.

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

(Examples 1 to 8 and Comparative Examples 1 to 4)
In the hydrometallurgical process of nickel oxide ore shown in FIG. 1, the operation of removing hydrogen sulfide in the post-sulfidation liquid was performed. Specifically, as shown in FIG. 1, first, in the leaching step S11, a slurry of nickel oxide ore is charged into an autoclave and leached with sulfuric acid under high temperature and high pressure to form a leachate and a leachate residue. In the solid-liquid separation step S12, calcium carbonate is added as a neutralizing agent to the leaching slurry obtained in the leaching step S11 to neutralize iron (III) hydroxide. A leached slurry containing iron (III) hydroxide is obtained by producing (preliminary neutralization step S121), and the obtained leached slurry containing iron (III) hydroxide is subjected to solid-liquid separation treatment to obtain a leachate and iron hydroxide (preliminary neutralization step S121). A leachate residue slurry containing III) was obtained (separation step S122).

Next, impurities were neutralized and removed from the leachate (neutralization step S13). Then, in the sulfurization step S14, the zinc sulfide produced by adding hydrogen sulfide gas as a sulfurizing agent to the neutralizing final solution obtained in the neutralization step S13 is separated (dezincination step), and after the dezincination step, the sulfurizing agent is separated. The nickel sulfide produced by adding hydrogen sulfide gas was recovered (nickel recovery step). By the sulfurization reaction in this sulfurization step S14, nickel and cobalt in the neutralization final liquid were sulfurized, and a nickel-cobalt mixed sulfurized product was produced. The sulfurized product produced was recovered by solid-liquid separation of the sulfurized slurry with a thickener.

On the other hand, the concentration of hydrogen sulfide dissolved in the post-sulfide liquid after the sulfide was separated and recovered was 20 to 400 mass ppm. Therefore, a treatment was performed to remove the hydrogen sulfide dissolved in the after-sulfurized liquid (sulfide agent removing step S30).

In the hydrogen sulfide removal treatment (sulfide removal step S30), calcium carbonate is used as a neutralizing agent (basic compound) for the leachate residue slurry obtained in the solid-liquid separation step S12 of the wet smelting process of nickel oxide ore. And calcium hydroxide were added to adjust the pH to 8.5 to 9.5 (wastewater treatment step S20), and the leached residue slurry after the obtained wastewater treatment step S20, that is, the leached residue containing iron (III) hydroxide was obtained. , Supply to the liquid after sulfidation. In all Examples 1 to 8 and Comparative Examples 1 to 4, the leachate residue containing iron (III) hydroxide was added and sulfuric acid was not added. The amount of free sulfuric acid in the leaching slurry was changed to change the Fe ³⁺ concentration in the leaching slurry of Examples 1 to 8 and Comparative Examples 1 to 4.

The sulfurizing agent removing step S30 was carried out in an aeration tank in which the post-sulfurized liquid after adding the leachate residue containing iron (III) hydroxide was stirred and air was blown into it. Further, the gas in the aeration tank after the sulfide removing step S30 was transferred to the abatement tower, brought into contact with sodium hydroxide in the abatement tower, and then discharged as exhaust gas from the exhaust gas discharge port of the abatement tower. Further, the post-sulfurized liquid that has passed through the sulfurizing agent removing step S30 was discharged to the wastewater treatment step S20.

The post-sulfurized liquid supplied to the sulfide removing step S30 has a nickel concentration of 0.02 to 0.10 g / L, an iron concentration of 0.6 to 1.4 g / L, and an aluminum concentration of 3.5 to 8. The magnesium concentration was 3.5 to 8.5 g / L at 0 g / L.

The leaching residue containing iron (III) hydroxide added to the post-sulfurized liquid is composed of a neutralization treatment residue (wastewater treatment wastewater) and a solution (wastewater treatment final liquid). The neutralization treatment residue (wastewater treatment product) had a specific gravity of 1.15 to 1.35 g / cm ³ , a solid content concentration of 20 to 35% by mass, and an iron grade of 35 to 45% by mass. The solution (wastewater treatment final solution) had a nickel concentration of 0.1 mg / L or less, a cobalt concentration of 0.05 mg / L or less, and an iron concentration of 0.1 mg / L or less.

Further, in order to suppress the influence of operational fluctuations, the starting liquid flow rate supplied to the nickel recovery process is 1200 to 1400 m ³ / Hr, the starting liquid temperature is 73 ° C., and the flow rate of the after-sulfurized liquid supplied to the sulfide removing step S30. Is 500 to 700 m ³ / Hr, the flow rate of the post-sulfurized liquid after the sulfide removal step S30 discharged to the wastewater treatment step S20 is 500 to 700 m ³ / Hr, and leaching containing iron (III) hydroxide added to the post-sulfurized liquid. The supply flow rate of the residue was 40 to 50 m ³ / Hr, and the aeration flow rate of the aeration tank was 2700 to 3100 Nm ³ / Hr.

Tables 1 and 3 show the measurement results of the Fe ³⁺ concentration in the leachate slurry and the hydrogen sulfide gas concentration in the exhaust gas of the exhaust gas outlet. The pH of the post-sulfidation solution after the treatment after the sulfurizing agent removing step S30 was 1.5 to 2.0.

As shown in Table 1 and FIG. 3, a leachate residue slurry (a leachate residue containing iron (III) hydroxide) is added in the sulfurizing agent removing step S30, and the Fe ³⁺ concentration in the leachate slurry is 2.90 g / L or more. In Examples 1 to 8, the hydrogen sulfide gas concentration is lower and hydrogen sulfide can be significantly reduced as compared with Comparative Examples 1 to 4 in which the Fe ³⁺ concentration in the leachate slurry is less than 2.90 g / L. I understood.

Claims (7)

The leachate slurry obtained by acid leaching the nickel oxide ore with sulfuric acid at a temperature of 220 ° C to 280 ° C while pressurizing is solid-liquid separated to obtain a leachate containing nickel and a leachate residue, which is sulfurized with respect to the leachate. In a hydrometallurgical process in which sulfurization treatment is performed with an agent to generate a sulfurized nickel and a post-sulfide liquid, sulfurization is performed to remove the sulfurizing agent dissolved in the post-sulfide liquid obtained by separating the sulfurized nickel. It ’s a method of removing the agent.
In the acid leaching, the Fe ³⁺ concentration in the obtained leaching slurry is set to 2.9 g / L or more and 3.6 g / L or less .
In the solid-liquid separation, the leached slurry is neutralized to generate iron (III) hydroxide to obtain a leached slurry containing iron (III) hydroxide, and then the iron (III) hydroxide is contained. The leachate slurry was subjected to solid-liquid separation treatment to obtain a leachate containing nickel and a leachate residue containing iron (III) hydroxide.
A method for removing a sulfurizing agent, which fixes and removes the sulfurizing agent contained in the post-sulfurizing liquid by adding a leachate residue containing the iron (III) hydroxide to the post-sulfurizing liquid. Wastewater treatment for detoxifying the leachate residue containing the iron (III) hydroxide obtained by solid-liquid separation of the leachate slurry by neutralizing the post-sulfurized liquid in the wet smelting process. The method for removing a sulfide agent according to claim 1, wherein a leachate residue containing the iron (III) hydroxide after the wastewater treatment is added to the post-sulfurized liquid. In the neutralization treatment for the leaching slurry, the pH of the leaching slurry is set to 2.5 to 3.2.
The method for removing a sulfurizing agent according to claim 1 or 2. The method for removing a sulfurizing agent according to any one of claims 1 to 3, wherein sulfuric acid is added to the post-sulfurized liquid together with the leachate residue containing iron (III) hydroxide. The post-sulfurized solution is a sulfuric acid acidic solution having a nickel ion concentration of 0.02 to 0.10 g / L and containing at least one selected from iron, manganese, magnesium, aluminum and chromium, according to claims 1 to 4. The method for removing a sulfurizing agent according to any one. The method for removing a sulfurizing agent according to any one of claims 1 to 5, wherein the leachate residue containing the iron (III) hydroxide is added to the after-sulfurized liquid and aeration is performed. A leaching step of leaching nickel oxide ore with sulfuric acid at a temperature of 220 ° C. to 280 ° C. to obtain a leaching slurry while pressurizing, and a leaching solution containing nickel by solid-liquid separation of the leaching slurry obtained in the leaching step. In the solid-liquid separation step for obtaining the leaching residue and the neutralizing final solution containing nickel and the neutralizing starch containing an impurity element by adding a neutralizing agent to the leachate obtained in the solid-liquid separation step. The Japanese step, the sulfide step of subjecting the neutralized final solution obtained in the neutralization step to a sulfide treatment with a sulfide agent to obtain a nickel sulfide and a post-sulfurized solution, and the nickel sulfide are separated. A wet smelting method for nickel oxide ore, comprising a sulfide removing step of fixing and removing the sulfide contained in the obtained post-sulfurization liquid.
The solid-liquid separation step is a pre-neutralization step of subjecting the leaching slurry obtained in the leaching step to an iron hydroxide (III) to generate an leached slurry containing iron (III) hydroxide. And, the leaching slurry containing the iron (III) hydroxide obtained in the pre-neutralization step is subjected to solid-liquid separation treatment to obtain a leaching solution and a leaching residue containing iron (III) hydroxide. ,
In the leaching step, the Fe ³⁺ concentration in the leaching slurry is set to 2.9 g / L or more and 3.6 g / L or less .
In the sulfurizing agent removing step, a leachate residue containing iron (III) hydroxide is added to the post-sulfide liquid obtained by separating the sulfide of nickel, so that the liquid is contained in the post-sulfide liquid. A wet smelting method for nickel oxide ore that immobilizes and removes the sulfurizing agent.

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