JP6953988B2 - How to remove sulfide - Google Patents

Description

The present invention relates to a method for removing a sulfide agent for removing a sulfide agent such as hydrogen sulfide in a post-sulfurized liquid obtained through a sulfurization treatment in a hydrometallurgical process of nickel oxide ore.

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 energetically and cost-effective because it does not include reduction and drying steps and consists of a consistent wet process, unlike the pyrometallurgical 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.

A hydrometallurgical method for nickel oxide ore based on the high-pressure acid leaching method will be described with reference to FIG. FIG. 1 is a process diagram showing a flow of a hydrometallurgical method for nickel oxide ore. As shown in FIG. 1, the hydrometallurgical method for nickel oxide ore includes, for example, the following steps.
(A) Sulfuric acid is added to the nickel oxide ore slurry 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 S11 and solid-liquid separation step S12
(B) Neutralization step S13 in which a neutralizing agent is added to the leachate to obtain a neutralized starch slurry containing an impurity element and a neutralized liquid containing nickel.
(C) Sulfation step S14 in which the neutralized liquid is subjected to sulfurization treatment with hydrogen sulfide gas to obtain nickel sulfide and a post-sulfurization liquid (poor liquid).
(D) Wastewater treatment step S15 for neutralizing the post-sulfurization liquid after separation of nickel sulfide to make it harmless.

Hydrogen sulfide is dissolved in the post-sulfide liquid after the separation of nickel sulfide. Therefore, in order to remove the hydrogen sulfide, trivalent iron, for example, iron (III) hydroxide and sulfuric acid as described in Patent Document 1, are added to the post-sulfide liquid after separation of nickel sulfide. As a result, hydrogen sulfide can be removed by reacting iron (III) hydroxide with hydrogen sulfide dissolved in the post-sulfide liquid. The reduction reaction of iron (III) hydroxide with hydrogen sulfide is shown in the following formula (1).
Fe (OH) ₃ + 1 / 2H ₂ S + H ₂ SO ₄ → FeSO ₄ + 1 / 2S ⁰ + 3H ₂ O (1)

When removing the dissolved hydrogen sulfide in the post-sulfide 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.

The post-sulfurization liquid after removing the dissolved hydrogen sulfide is used as a cleaning liquid for cleaning the leachate residue in the solid-liquid separation step S12, and is harmless by adjusting the pH to near neutral in order to discharge it as wastewater to the outside of the factory. It is paid out to the wastewater treatment step S15. If the dissolved hydrogen sulfide in the post-sulfurization liquid is not sufficiently removed and remains, and is discharged to the solid-liquid separation step S12 or the wastewater treatment step S15, the odor of hydrogen sulfide is generated around the equipment. , There is a possibility that serious environmental troubles may occur, which causes problems in terms of environment and safety. When the removal of dissolved hydrogen sulfide is poor, it is necessary to take measures such as reducing the amount of hydrogen sulfide added and the process load in the sulfurization step S14 for obtaining nickel sulfide. The decrease in the actual nickel yield in the sulfurization step S14 is reduced, and the reduction in the process load leads to a reduction in the production of the mixed sulfide product. Therefore, it is one of the important treatments to sufficiently remove the dissolved hydrogen sulfide in the post-sulfurization liquid.

Further, in the conventional sulfurizing agent removing reaction, sulfuric acid is added as shown in the above formula (1), but the addition of sulfuric acid causes an increase in the amount of the neutralizing agent used in the wastewater treatment step S15 in the subsequent stage and thus an increase in cost. rice field. Therefore, there is a strong demand for an operation method that can achieve both maximization of product production and cost reduction.

For example, Patent Document 3 aims to effectively reduce the amount of sulfuric acid and a neutralizing agent used while effectively removing hydrogen sulfide dissolved in the post-sulfide liquid, and iron oxide is used with respect to the post-sulfide liquid. By adding the leachate residue after washing containing (III) and sulfuric acid and adjusting the pH in the range of 1.2 to 1.5, the iron oxide (III) contained in the leachate residue is reacted and dissolved. A method for removing hydrogen sulfide has been proposed.

However, it is desired to further improve the effect of reducing dissolved hydrogen sulfide.

Japanese Unexamined Patent Publication No. 2004-089915 JP 2015-127053 JP-A-2017-115231

The present invention has been made in view of such circumstances, and is a method for removing a sulfide agent, which removes a sulfide agent such as hydrogen sulfide from a sulfided liquid generated in a wet smelting process of nickel oxide ore. An object of the present invention is to provide a method for removing a sulfide agent, which can improve the effect of reducing the sulfide agent.

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-sulfidation liquid, the sulfurizing agent such as hydrogen sulfide can be immobilized by iron (III) sulfate contained in the leachate residue and removed from the post-sulfurization liquid. , And, it was found that the addition of sulfuric acid is not necessary for the reaction between iron (III) sulfate and a sulfurizing agent such as hydrogen sulfide. The present invention has been completed by finding that by adding a leachate residue containing (III), a method for removing a sulfide agent having a high effect of reducing the sulfide agent can be obtained. That is, the present invention provides the following.

(1) In the first invention of the present invention, a leachate 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 sulfurizing agent is used to generate a sulfide of nickel and a post-sulfurization liquid, the sulfide agent dissolved in the post-sulfidation liquid obtained by separating the sulfide of the nickel is used. A method for removing a sulfurizing agent to be removed, in which the leachate residue containing iron (III) sulfate is used as a trivalent iron ion source, and the leachate residue is added to the after-sulfide solution without adding sulfuric acid. This is a method for removing a sulfurizing agent, which fixes and removes the sulfurizing agent contained in the post-sulfurized liquid by adding the sulfurizing agent.

(2) In the second invention of the present invention, the leachation residue obtained by solid-liquid separation of the leaching slurry is rendered harmless by subjecting the post-sulfidation liquid to neutralization treatment in the hydrometallurgical process. This is the method for removing a sulfurizing agent according to the first invention, wherein the leachation residue after the wastewater treatment is added to the post-sulfurized liquid for the wastewater treatment.

(3) In the third invention of the present invention, the pH is set to 1.7 or more and 2.0 or less by adding the leachate residue to the after-sulfidated liquid without adding sulfuric acid. The method for removing a sulfurizing agent according to the present invention.

(4) In the fourth invention 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 third inventions, which is an acidic sulfuric acid solution containing the mixture.

(5) The fifth invention of the present invention is the method for removing a sulfurizing agent according to any one of the first to fourth inventions, wherein the leachate residue is added to the post-sulfurized liquid and aeration is performed. be.

According to the method for removing a sulfide agent of the present invention, the effect of reducing a sulfide agent such as hydrogen sulfide from the post-sulfurized liquid generated in the wet smelting process of nickel oxide ore can be improved, and hydrogen sulfide from the post-sulfurized liquid can be improved. It is possible to sufficiently remove the sulfurizing agent such as. Further, since sulfuric acid is not added when the sulfurizing agent is removed, the amount of sulfuric acid used and the amount of chemicals such as a neutralizing agent used in the wastewater treatment step can be reduced.

Then, according to the method for removing a sulfurizing agent of the present invention, the effect of reducing the sulfurizing agent can be improved, so that the occurrence of defective removal of the dissolved sulfurizing agent is suppressed, and the amount of the sulfurizing agent added in the sulfurizing step is reduced. It is expected that measures such as lowering the amount of sulfur will be suppressed, and the actual yield of nickel will be improved and the production of sulfur will be maximized. Further, since sulfuric acid is not added when removing the sulfurizing agent, the sulfuric acid cost can be reduced. Therefore, the industrial value of the present invention in the hydrometallurgical process of nickel oxide ore is extremely high.

It is a process diagram which shows the flow of the wet smelting method 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 measurement result of an Example and a comparative example.

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 a sulfide agent according to the present embodiment, a leachate 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, a wet smelting process of nickel oxide ore (hereinafter, simply referred to as "wet smelting process") for obtaining nickel sulfide by subjecting it to sulfurization treatment with a sulfide agent to generate sulfide of nickel and a liquid after sulfurization. ) 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 use iron sulfate (a trivalent iron ion source) as a trivalent iron ion source in a post-sulfide solution obtained by separating nickel sulfide in a hydrometallurgy process. Using the leachate residue containing III), the leachate residue is added to the post-sulfidation solution without adding sulfuric acid. As a result, as will be described in detail later, the sulfurizing agent such as hydrogen sulfide dissolved in the liquid after sulfurization is fixed and removed (recovered) by iron (III) sulfate 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) sulfate, and this elemental sulfur is precipitated and removed.

According to such a method, the effect of reducing the sulfide agent such as hydrogen sulfide from the post-sulfidation liquid generated in the wet smelting process of nickel oxide ore can be improved, and the sulfide agent such as hydrogen sulfide from the post-sulfidation liquid can be improved. Can be sufficiently removed. Further, since sulfuric acid is not added when the sulfurizing agent is removed, the amount of sulfuric acid used and the amount of chemicals such as a neutralizing agent used in the wastewater treatment step can be reduced.

Then, according to the method for removing a sulfurizing agent of the present invention, the effect of reducing the sulfurizing agent can be improved, so that the occurrence of defective removal of the dissolved sulfurizing agent is suppressed, and the amount of the sulfurizing agent added in the sulfurizing step is reduced. It is expected that measures such as lowering the amount of sulfur will be suppressed, and the actual yield of nickel will be improved and the production of sulfur will be maximized. Further, since sulfuric acid is not added when removing the sulfurizing agent, the sulfuric acid cost can be reduced. Therefore, the industrial value of the present invention in the hydrometallurgical process of nickel oxide ore is extremely high.

≪2. Wet smelting process of nickel oxide ore ≫
First, prior to a more specific explanation of the method for removing the sulfurizing agent, the wet smelting of nickel oxide ore is performed using FIG. 2, 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. 2, this hydrometallurgy process includes a leaching step S11 in which nickel oxide ore as a raw material is leached with acid 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 slurry, and a neutralization step for obtaining a neutralized starch slurry containing impurities and a post-neutralized liquid containing nickel by adding a neutralizing agent to the leachate. It has S13 and a sulphurization step S14 in which a liquid after neutralization is subjected to a sulphurization treatment with a sulfide agent to obtain nickel sulfide and a liquid after sulphurization. Further, the wastewater treatment step S20 is provided in which the post-sulfidation liquid separated in the sulfurization step S14 is neutralized to make it harmless.

In the method for removing a sulfurizing agent according to the present embodiment, the post-sulfidizing liquid (poor liquid) obtained by the hydrometallurgical process of this nickel oxide ore is treated, and the sulfurizing agent dissolved in the post-sulfurizing 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 agitated while pressurizing at a temperature of 220 ° C. to 280 ° C., and a nickel-containing leachate and a leachate residue are subjected to stirring treatment. A leachate slurry consisting of

Here, examples of nickel oxide ore mainly include so-called laterite ores such as limonite ore and saprolite ore. The nickel content of laterite ore is usually 0.8-2.5% by weight and is contained as a hydroxide or magnesium silicate mineral.

(2) Solid-Liquid Separation Step In the solid-liquid separation step S12, the leachate containing valuable metals such as nickel and cobalt and hematite (Fe) are washed while washing the leachate slurry consisting of the leachate and the leachate residue obtained in the leachate step S11. _{2 O 3,} a step of solid-liquid separation and leach residue slurry containing iron oxide (III)). In this solid-liquid separation step S12, for example, after mixing the leachate slurry with the cleaning liquid, a solid-liquid separation treatment is performed by a solid-liquid separation facility such as a thickener using a coagulant supplied from a coagulant supply facility or the like. Specifically, first, the leaching slurry is diluted with a washing liquid, and then the leaching residue slurry in the leaching slurry is concentrated as a thickener sediment.

The leachate separated in the solid-liquid separation step S12 is transferred to the neutralization step S13, while the leachate residue slurry is recovered from the bottom of the thickener. Since the leaching residue slurry 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 slurry is also neutralized in step S13. It may be transferred to.

(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 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 liquid are obtained. By the neutralization treatment in this neutralization step S13, valuable metals such as nickel and cobalt are contained in the neutralized liquid, and most of the iron becomes a neutralized starch slurry.

As the neutralizing agent, conventionally known ones can be used, and examples thereof include calcium carbonate, slaked lime, 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 liquid 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 neutralized product slurry obtained in the neutralization step S13 contains a valuable metal such as nickel or cobalt, the neutralized product slurry may be supplied to the solid-liquid separation step S12.

(3) Sulfide Step The sulfurization step S14 is a step of subjecting the neutralized 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 the 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 liquid to cause a sulfurization reaction in which nickel or cobalt contained in the neutralized liquid is formed into a sulfide form. As a result, a nickel sulfide having a small amount of impurity components and a post-sulfurization liquid (poor liquid) in which the nickel concentration is stabilized at a low level are generated. When zinc is contained in the liquid after neutralization, zinc can be selectively separated as sulfide using a sulfide agent prior to adding a sulfide agent to generate nickel sulfide. (Dezincification process). That is, a dezincination step of forming zinc sulfide by adding a sulfide agent to the post-neutralization liquid obtained in the neutralization step S13 and separating the zinc sulfide to obtain a nickel recovery mother liquor containing 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, cost and the like.

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

Here, in the method for removing the sulfurizing agent according to the present embodiment, the post-sulfidation liquid obtained by the sulfurization treatment in the sulfurization step S14, that is, the slurry after the sulfurization treatment is subjected to a solid-liquid separation treatment. The treated solution is the post-sulfurized liquid.

(4) Wastewater treatment step 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, has a predetermined pH that satisfies the discharge standard. Wastewater treatment is performed to make it harmless by performing neutralization treatment to adjust to the range. As a result, components such as iron, magnesium, and manganese are removed.

In the present embodiment, the post-sulfidation liquid from which the dissolved hydrogen sulfide and other sulfurizing agents have been removed through the sulfurizing agent removing step S30, which is a treatment for removing the sulfurizing agent from the post-sulfidizing liquid, which will be described in detail later, is drained. 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, a neutralizing agent such as calcium carbonate (limestone) slurry or calcium hydroxide (slaked lime) slurry is added. This allows the pH to be near neutral (eg, pH 8-9).

Further, in the neutralization treatment in the wastewater treatment step S20, a first-stage neutralization treatment using limestone as a neutralizer (first step) and a second-stage neutralization treatment using slaked lime as a neutralizer. A stepwise process consisting of (second step) can be performed. By performing the stepwise neutralization treatment in this way, it is possible to efficiently and effectively perform the neutralization treatment.

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-sulfidation solution is raised to 8-9 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 the tailing dam (tailing residue). On the other hand, the solution after the wastewater treatment step S20 (the liquid after the wastewater treatment) satisfies the emission standard and is discharged to the outside of the system. In the neutralization treatment in the wastewater treatment step S20, the iron contained in the post-sulfurized liquid is immobilized and separated in the form of _{iron hydroxide (Fe (OH) 3).}

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, the larger the amount of acid, sulfurizing agent, and impurities remaining in the after-sulfurized liquid, the larger the amount of neutralizing agent used.

In this respect, in the present embodiment, prior to the wastewater treatment step S20, in the sulfurizing agent removing step S30, the after-sulfidation liquid obtained in the sulfurization step S14 is sulphurized with hydrogen sulfide or the like dissolved in the after-sulfidation liquid. I try to remove the agent. Then, in the sulfurizing agent removing step S30, iron (III) sulfate contained in the leachate residue is used as a trivalent iron ion source for oxidatively immobilizing a sulfurizing agent such as hydrogen sulfide, and sulfuric acid is not added. There is. 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.

≪3. Detailed explanation of the method for removing the sulfide 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-sulfidation 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 post-sulfurized liquid in this way, when the post-sulfurized liquid is discharged to the solid-liquid separation step S12 or the wastewater treatment step S20, an odor of hydrogen sulfide is generated around the equipment. This causes environmental and safety problems, such as the possibility of environmental troubles. In addition, hydrogen sulfide cannot be discharged to the outside of the system while it remains dissolved.

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 collected 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 as an example.

Specifically, in the sulfurizing agent removing step S30, a leachate residue containing iron (III) sulfate was used as a trivalent iron ion source, and the leachate residue was added to the after-sulfide solution containing hydrogen sulfide without adding sulfuric acid. Is added to fix and remove hydrogen sulfide contained in the post-sulfidation liquid in the form of solid sulfur.

The post-sulfuric acid solution obtained in the sulphurization step S14 has, for example, a nickel ion concentration of about 0.04 g / L to 0.10 g / L, and sulfuric acid containing impurities such as iron, manganese, magnesium, aluminum, chromium, and lead. It is an acidic solution. The pH of the post-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-sulfurization liquid at a concentration of, for example, about 10 mg / L to 150 mg / L.

Conventionally, in the removal treatment of a sulfurizing agent disclosed in, for example, Patent Document 3, the leachate residue obtained by solid-liquid separation of the leachate slurry is transferred to a leachate residue cleaning step and then subjected to a cleaning treatment. Iron (III) oxide contained in the leachate residue after washing was used as a trivalent iron ion source for immobilizing hydrogen sulfide. At this time, in order to make the iron (III) oxide act as a trivalent iron ion source, the iron (III) oxide was dissolved by adding sulfuric acid together. Specifically, as shown in the following formulas (2) and (3), iron (III) oxide was dissolved in sulfuric acid to produce iron (III) sulfate (formula (2)), and the produced iron sulfate (formula (2)) was produced. III) was used for oxidative fixation of hydrogen sulfide (Equation (3)).
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)

However, in such a conventional method, the removal efficiency of hydrogen sulfide may be insufficient, and sulfuric acid is used to dissolve iron (III) oxide used as a trivalent iron ion source. In order to improve the removal efficiency of hydrogen sulfide, the amount of sulfuric acid used had to be increased. Further, when the amount of sulfuric acid used increases, it has been a factor of increasing the amount of the neutralizing agent used in the subsequent wastewater treatment (wastewater treatment step S20) for the post-sulfurized liquid.

On the other hand, in the sulfurizing agent removing step S30 according to the present embodiment, iron (III) sulfate contained in the leachate residue is used as a trivalent iron ion source for immobilizing hydrogen sulfide. The leachate residue obtained through the solid-liquid separation treatment includes not only hematite (iron oxide (III)) but also iron sulfate (III) that could not be completely hematite. In the present embodiment, iron (III) sulfate thereof is positively used as a trivalent iron ion source instead of iron (III) oxide contained in the leachate residue.

When iron (III) sulfate contained in the leachate residue is used as a trivalent iron ion source, the reaction of the following formula (4) occurs, so that hydrogen sulfide dissolved in the post-sulfurization liquid is oxidized to form solid sulfur. It is fixed. Further, iron (III) sulfate reacts with hydrogen sulfide to produce iron (II) sulfide, and the produced iron (II) sulfate causes the reaction of the following formula (5) to cause sulfurization. Hydrogen sulfide in the after-liquid is further decomposed. In this way, by using iron (III) sulfate as the trivalent iron ion source, hydrogen sulfide can be decomposed and removed more effectively, and the removal efficiency of hydrogen sulfide can be improved as compared with the conventional case. Can be done.
Fe ₂ (SO ₄ ) ₃ + H ₂ S → _{2 FeSO 4} + H ₂ SO ₄ + S ⁰ (4)
FeSO ₄ + H ₂ S → FeS + H ₂ SO ₄ (5)

Here, as described above, the leachate residue contains not only iron (III) sulfate but also iron (III) oxide, and such a leachate residue is added to the post-sulfurization solution to remove hydrogen sulfide. At the same time, when sulfuric acid is added at the same time, a reaction (the above formula (2)) for dissolving iron (III) oxide to iron (III) sulfate occurs. Therefore, in the sulfurizing agent removing step S30, the leachate residue is added to the after-sulfurized liquid without adding sulfuric acid.

In this way, by adding the leachate residue containing iron (III) sulfate to the post-sulfurization solution without adding sulfuric acid, the reaction of iron oxide (III) contained in the leachate residue is suppressed, and iron (III) sulfate is used. The reactions of the above formulas (4) and (5) are positively generated. Thereby, the effect of reducing hydrogen sulfide can be improved.

In addition, when sulfuric acid is attached to the leachate residue added to the liquid after sulfide, the dissolution reaction of iron oxide (III) also proceeds, and the action of iron (III) sulfate contained in the leachate residue is reduced. I will end up. In particular, since the leaching residue obtained through the solid-liquid separation step S12 is based on the leaching slurry obtained by leaching sulfuric acid in the leaching step S11, sulfuric acid adheres when the leaching residue is added to the post-sulfidation liquid. It is preferable that the state is not equal.

Therefore, in the present embodiment, the leaching residue containing iron (III) sulfate obtained through the solid-liquid separation treatment is charged into the treatment in the wastewater treatment step S20 in the hydrometallurgical process, and the wastewater treatment step is carried out. Neutralization treatment is performed in S20. As described above, in the wastewater treatment step S20, a neutralization treatment is performed in which a neutralizing agent such as calcium carbonate or calcium hydroxide is added to adjust the pH of the solution to about 8 to 9. Therefore, by charging the leachate residue into the treatment in the wastewater treatment step S20, the acid adhering to the leachate residue can be neutralized.

Then, the leaching residue after passing through such a wastewater treatment step S20 (hereinafter, also referred to as “leaching residue after wastewater treatment” for convenience) is transferred to the sulfide removing step S30 and added to the post-sulfurized liquid. , Iron (III) sulfate contained in the leaching residue can be allowed to act while suppressing the reaction of iron (III) oxide.

In the treatment in the sulfurizing agent removing step S30, the pH of the post-sulfurized liquid can be adjusted to 1.7 or more and 2.0 or less by adding a leachate residue containing iron (III) sulfate without adding sulfuric acid. It is preferable to cause the reaction while maintaining the pH. For example, when the pH of the after-sulfurization liquid becomes less than 1.7 by adding sulfuric acid or the like, the reaction of the above formula (2) preferentially occurs and becomes a reaction mainly composed of iron (III) oxide, and the efficiency of hydrogen sulfide oxidation is high. May decrease. On the other hand, when the pH of the post-sulfidation liquid exceeds 2.0, it is generally necessary to add a basic neutralizing agent to the post-sulfidation liquid. Hereinafter, the “post-sulfide liquid after treatment”) may be used as a cleaning liquid or the like in the solid-liquid separation step S12, so that the load due to the neutralized starch in the solid-liquid separation step S12 increases. In addition, the addition of the neutralizing agent may cause scale to be generated in the reaction vessel, increasing the frequency of open inspections and making it necessary to carry out scale removal work. Although there is a method of using NaOH instead of limestone as the neutralizing agent, it is not preferable because the production cost is significantly increased.

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) sulfate contained in the leachate 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 equipped with an annular aeration tube, the leaching residue is added without adding sulfuric acid, and while stirring, aeration is performed at a ratio of 1.8 Nm ^{3 or more per 1 m 3 of the post-sulfurized liquid slurry.} do. 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.

As described above, according to the method for removing hydrogen sulfide according to the present embodiment, iron (III) sulfate in the leachate residue is used as a reaction subject for hydrogen sulfide oxidation as a trivalent iron ion source. Since the effect of reducing hydrogen sulfide can be improved, hydrogen sulfide can be sufficiently removed. In addition, it is no longer necessary to use sulfuric acid, which was used for dissolving hematite (iron (III) oxide) as in the conventional method.

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 hydrogen sulfide is removed without adding sulfuric acid. Therefore, in the wastewater treatment for the post-sulfidation liquid after the treatment, 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 9)
In the hydrometallurgical process of nickel oxide ore shown in FIG. 2, the operation of removing hydrogen sulfide in the post-sulfidation liquid was performed. Specifically, as shown in FIG. 2, first, a slurry of nickel oxide ore is charged into an autoclave and leached with sulfuric acid under high temperature and high pressure to contain a leached liquid and a leached residue. (Leaching step S11), solid-liquid separation was performed using a washing liquid to obtain a leachate and a leachate residue slurry (solid-liquid separation step S12).

Next, impurities were neutralized and removed from the leachate (neutralization step S13). Then, in the sulfurization step S14, the zinc sulfide formed by adding hydrogen sulfide gas as a sulfurizing agent to the neutralized liquid obtained in the neutralizing step is separated (dezincination step), and after the dezincification step, it is used as a sulfurizing agent. The nickel sulfide formed by adding hydrogen sulfide gas was recovered (nickel recovery step). By the sulfurization reaction in this sulfurization step S14, nickel and cobalt in the liquid after neutralization were sulfurized to produce a nickel-cobalt mixed sulfurized product. The produced sulfide 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 (poor liquid) after the sulfide was separated and recovered was 100 mass ppm or more. 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 agent removal step S30), a delime slurry is added as a neutralizing agent to the leachate residue obtained in the solid-liquid separation step S12 of the hydrometallurgical process of nickel oxide ore to adjust the pH. It was set to 9 (wastewater treatment step S20), and the leachation residue slurry obtained in this wastewater treatment step S20 was supplied to the post-sulfidation liquid. The amount of the leachate residue slurry after the wastewater treatment step S20 supplied to the liquid after sulphurization of Examples 1 to 9 was changed, and the reaction tank pH of each Examples 1 to 9 (the leachate residue slurry after the wastewater treatment step S20 was added. The pH of the post-slurry liquid was changed. In Examples 1 to 9, sulfuric acid was not added in the sulfurizing agent removing step S30. Further, the sulfide removing step S30 was carried out in an aeration tank in which the liquid after brewing after adding the leaching residue slurry after the wastewater treatment step S20 was agitated and air was blown into the liquid. Further, the gas in the aeration tank after the sulfide removing step S30 was transferred to the aeration tower, brought into contact with sodium hydroxide in the aeration tower, and then discharged as exhaust gas from the exhaust gas discharge port of the aeration tower. Further, the post-sulfurized liquid that has passed through the sulfurizing agent removing step S30 is discharged to the wastewater treatment step S20.

The post-sulfurization 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 2.5 to 4. The magnesium concentration was 5.0 to 8.5 g / L at 0 g / L, and the pH was 1.5 to 1.9. The leachated residue slurry added to the post-sulfurized liquid after the wastewater treatment step S20 has a nickel grade of 0.1% by mass or less, a cobalt grade of 0.01% by mass or less, an iron grade of 45% by mass or more, and sulfuric acid. It did not contain iron (III) sulfate and iron (III) oxide. Further, in order to suppress the influence of operational fluctuations, the starting liquid flow rate supplied to the nickel recovery step is 1200 to 1300 m ³ / Hr, the starting liquid temperature is 73 ° C., and after the sulfide removing step S30 dispensed to the wastewater treatment step S20. The flow rate of the post-sulfurized liquid is 500 to 600 m ³ / Hr, the supply flow rate of the leachate residue slurry after the wastewater treatment step S20 added to the post-sulfurized liquid is 45 to 55 m ³ / Hr, after the wastewater treatment step S20 added to the post-sulfurized liquid. The specific gravity of the leachate residue slurry was 1.22 to 1.28 t / m ³ , and the aeration flow rate of the aeration tank was 2950 to 3050 Nm ³ / Hr.

Tables 1 and 3 show the measurement results of the liquid pH (reaction tank pH) of the aeration tank in which the sulfide removing step S30 was performed and the hydrogen sulfide gas concentration in the exhaust gas of the exhaust gas outlet.

As shown in Table 1 and FIG. 3, the hydrogen sulfide gas concentration was 100% by mass or more, which is the upper limit of detection, at the inlet of the sulfurizing agent removing step, whereas the hydrogen sulfide gas was drained without adding sulfuric acid in the sulfurizing agent removing step. In Examples 1 to 9 in which the pH was set to 1.7 or more and 2.0 or less by adding the leachate residue slurry after the treatment step S20, the hydrogen sulfide gas concentration at the exhaust gas discharge port of the wastewater treatment step S20 was 10 mass ppm. It was as follows. As described above, in Examples 1 to 9, the hydrogen sulfide concentration of the exhaust gas was 10 mass ppm, and hydrogen sulfide was sufficiently removed.

(Comparative Examples 1 to 15)
The same operation as in Example 1 was carried out except that sulfuric acid was also added in the sulfurizing agent removing step S30 so that the liquid pH of the aeration tank became the value shown in Table 1. The results are shown in Table 1 and FIG. As shown in Table 1 and FIG. 3, the hydrogen sulfide gas concentration at the exhaust gas discharge port in the wastewater treatment step S20 was 12 to 19 mass ppm.

From the above results, by adding the leachate residue slurry and not adding sulfuric acid as in Examples 1 to 9, the wastewater treatment step S20 is compared with Comparative Examples 1 to 15 in which the leachate residue slurry was added and sulfuric acid was added. It was found that the concentration of hydrogen sulfide gas at the exhaust gas outlet of the above can be significantly reduced. Therefore, by adding the leachate residue slurry and not adding sulfuric acid as in Examples 1 to 9, iron (III) sulfate contained in the leachate residue can be reacted with hydrogen sulfide, and hydrogen sulfide from the post-sulfide liquid can be reacted. It was found that the reduction effect of hydrogen sulfide can be improved.

Further, it was found that since sulfuric acid is not added in the sulfurizing agent removing step S30, the amount of the neutralizing agent used in the wastewater treatment step S20 after the sulfurizing agent removing step S30 can be significantly reduced.

The reason why the hydrogen sulfide gas concentration at the exhaust gas discharge port of the wastewater treatment step S20 increased in Comparative Examples 1 to 15 is that the leachate residue slurry is added and sulfuric acid is added to the post-sulfidation liquid in which hydrogen sulfide is dissolved. Therefore, it is considered that the reaction was mainly composed of hematite (iron (III) oxide), and the oxidation efficiency of hydrogen sulfide decreased.

Claims (3)

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 sulfurized with a sulfurizing agent to obtain nickel. A method for removing a sulfide agent, which removes a sulfide agent dissolved in the sulfided liquid obtained by separating the sulfide of the nickel in a hydrometallurgical process for producing a sulfide and a post-sulfide liquid.
Using the leachate residue containing iron (III) sulfate as a trivalent iron ion source,
The relative sulfide solution after, the addition of the leach residue after subjected without the addition of sulfuric acid, before Symbol wastewater treatment for detoxification by performing neutralization treatment against liquid after sulfurization, the sulfide A method for removing a sulfurizing agent, which fixes and removes the sulfurizing agent contained in the after-sulfide liquid by setting the pH of the after-liquid to 1.7 or more and 2.0 or less. The post-sulfuric acid 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 claim 1. How to remove sulfide. The method for removing a sulfurizing agent according to claim 1 or 2, wherein the leachate residue is added to the post-sulfurized liquid and aeration is performed.

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