JP6996328B2 - Dezincification method, wet smelting method of nickel oxide ore - Google Patents

Description

The present invention relates to a dezincification treatment method, and more specifically, a mother liquor for recovering nickel by separating zinc from a neutralization final solution containing nickel, cobalt, and zinc in a hydrometallurgical method for nickel oxide ore. The present invention relates to a treatment method in a dezincification step for producing a nickel oxide ore, and a hydrometallurgical method for nickel oxide ore thereof.

As a hydrometallurgical method for nickel oxide ore, there is a high-pressure acid leaching method (HPAL method) using sulfuric acid. This method is advantageous in terms of energy and cost because it consists of a consistent wet process that does not include a reduction and drying process, unlike the dry smelting method which is a conventional general method for smelting nickel oxide ore. Further, it has an advantage that a sulfide containing nickel and cobalt (hereinafter, also referred to as "nickel-cobalt mixed sulfide") having a high purity of nickel grade of about 50% by mass to 60% by mass can be obtained. There is.

The hydrometallurgical process of nickel oxide ore by the high pressure acid leaching method includes, for example, the following steps. (A) Leaching step of adding sulfuric acid to a slurry of nickel oxide ore and leaching under high temperature and high pressure (b) While washing the obtained leaching slurry in multiple stages, the leaching residue is separated to remove impurity elements together with nickel and cobalt. Solid-liquid separation step to obtain a leachate containing leachate (c) The pH of the leachate is adjusted to perform neutralization treatment, and a neutralized starch containing an impurity element is separated to obtain a neutralized final liquid containing nickel and cobalt. Step (d) By adding hydrogen sulfide gas to the neutralization final solution, sulfide containing zinc and copper (hereinafter, also referred to as “zinc sulfide”) is generated, and the zinc sulfide is separated and dezincinated. Dezincination step to obtain final solution (mother solution for recovering nickel) (e) By adding hydrogen sulfide gas to the dezincinated final solution, a mixed sulfide containing nickel and cobalt is formed, and the mixed sulfide is separated and recovered. Nickel recovery process

Here, in the dezincification step in the wet smelting process described above, the neutralizing final liquid is introduced into the sulfurization reaction tank, and a sulfurizing agent such as hydrogen sulfide gas or sodium hydrosulfide is added to the neutralizing final liquid. Zinc and copper contained therein are sulfurized, and then solid-liquid separation is performed by a solid-liquid separation device such as a filter press to obtain zinc sulfide and a mother liquor for recovering nickel containing nickel and cobalt.

By the way, the mixed sulfide obtained by the hydrometallurgy process is used as a raw material for further refining electric nickel and electric cobalt. Therefore, in the dezincination step of producing the nickel recovery mother liquor, it is required to reduce the zinc concentration in the dezincification final solution to 0.001 g / L or less.

Further, in the dezincination step, a part of the produced zinc sulfide is repeatedly added to the neutralization final solution (see, for example, Patent Document 1). That is, since the zinc sulfide to be added repeatedly is already filtered by a filtration device and has particles of about several μm to more than ten μm suitable as seed crystals, the zinc sulfide produced by the treatment in the dezincification step. The particle size will be further increased, and the effect of improving the filterability can be obtained more stably. Furthermore, by repeating the nickel contained in the zinc sulfide discharged to the outside of the system in the process, the lost nickel can be recovered and the nickel recovery loss as a process can be reduced. can.

In the dezincification step, zinc sulfide is reacted with iron (II) sulfide contained in the precipitate (dezincination residue) generated in the dezincification step when the zinc in the liquid is passed through the filtration device. Precipitate as. Therefore, the zinc concentration of the solution after passing through the filtration device is usually low. In the following, the rate at which the zinc concentration in the solution decreases before and after passing the liquid through the filtration device is referred to as the "zinc removal rate".

However, when the amount of iron (III) hydroxide contained in the dezincinated residue increases, zinc sulfide dissolves in the liquid as zinc ions by the reaction with the iron (III) hydroxide, and the zinc removal rate increases. It may drop sharply. As a result, the zinc concentration in the dezincified final solution obtained through the dezincification step increases, and the zinc concentration in the nickel-cobalt mixed sulfide (product) recovered through the nickel recovery step increases accordingly. Is a problem.

In addition, when the zinc removal rate decreases, in order to keep the zinc concentration in the product nickel-cobalt mixed sulfide below the level required by the customer (for example, 250 ppm or less), the zinc concentration is in the stage before passing the liquid through the filtration device. Is required to be lower than usual, and for that purpose, it is necessary to increase the amount of a sulfurizing agent such as hydrogen sulfide gas added in the treatment in the dezincification step. However, an increase in the amount of sulfurizing agent added such as hydrogen sulfide gas not only increases the drug cost but also increases the amount of nickel recovery loss due to the coprecipitation of nickel in the dezincinated residue, which hinders economic operation. It causes.

From the above circumstances, there is a demand for a method capable of maintaining a higher zinc removal rate in the treatment in the dezincification step in the hydrometallurgical process of nickel oxide ore.

Japanese Unexamined Patent Publication No. 2010-37626

The present invention has been proposed in view of such circumstances. For example, in a dezincification treatment applicable to a dezincification step of a hydrometallurgical process of nickel oxide ore, zinc is removed before and after passing the liquid through a filtration device. It is an object of the present invention to provide a method capable of improving the rate and maintaining the high removal rate.

The present inventor has made extensive studies to solve the above-mentioned problems. As a result, in the dezincification treatment, a part of the dezincination residue recovered by passing the liquid through the filtration device after the sulfide reaction is repeatedly added to the reaction vessel in which the sulfide reaction is carried out, and at that time, the dezincination residue is repeatedly added to the reaction vessel. The present invention has been completed by finding that the zinc removal rate can be improved by setting the amount of solids in the flow rate of the slurry containing the above to a specific range with respect to 1 m ³ of the starting liquid supplied to the reaction vessel. I let you.

(1) The first invention of the present invention contains zinc sulfide by using a solution containing nickel, cobalt, and zinc as the starting solution and adding a sulfide agent to the starting solution to perform sulfide treatment. In the dezincification treatment method for obtaining a residue and a solution containing nickel and cobalt, the solution after the sulfurization treatment is passed through a filtration device to recover the zinc-containing residue, and a part of the recovered residue is collected. The amount of solid in the flow rate of the slurry containing the residue repeatedly added to the reaction vessel containing the starting solution is 1 g or more with respect to 1 m ³ of the starting solution supplied to the reaction vessel. It is a dezincification treatment method that makes the range of 10 g or less.

(2) In the second invention of the present invention, in the first invention, the starting liquid contains trivalent iron and is contained in the residue as iron (III) hydroxide by the sulfurization treatment. This is a dezincification treatment method.

(3) The third invention of the present invention is a leaching step of acid leaching a slurry of nickel oxide ore to obtain a leachate containing nickel and cobalt, and neutralizing the obtained leachate to remove impurities. Dezincination to generate and separate zinc sulfide contained in the neutralizing final solution by adding a sulfide agent to the neutralizing step and the neutralizing final solution after the neutralization treatment as the starting solution and performing the sulfide treatment. A wet smelting method for nickel oxide ore, comprising a step and a nickel recovery step of producing and recovering a mixed sulfide of nickel and cobalt by adding a sulfide agent to the dezincified final solution, wherein the dezinc is dezincinated. In the step, a sulfide agent is added to the reaction vessel containing the dezincinated initial solution to perform sulfide treatment, and a part of the residue containing zinc sulfide recovered by passing the liquid through a filtration device is repeatedly put into the reaction vessel. At that time, the amount of solid in the slurry flow rate containing the residue repeated in the reaction vessel shall be in the range of 1 g or more and 10 g or less with respect to the dezincination starting liquid amount of 1 m ³ supplied to the reaction vessel. This is a wet smelting method for zinc oxide ore.

According to the present invention, in the dezincification treatment of removing zinc by subjecting a solution containing nickel, cobalt, and zinc to zinc treatment, the zinc removal rate before and after passing the liquid through a filtration device after the sulfurization treatment is improved. , And its high removal rate can be maintained.

It is a process diagram which shows an example of the flow of the wet smelting process of nickel oxide ore. It is a block diagram which shows the structure of the processing equipment which performs dezincification treatment. It is a graph which shows the result of the zinc removal rate (%) with respect to the repetition amount (g / m ³ ) in a residue system in 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. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

≪1. Overview ≫
In the dezincification treatment method according to the present embodiment, a solution containing nickel, cobalt, and zinc is used as the starting liquid, and a sulfide treatment such as hydrogen sulfide gas is added to the starting liquid to perform the sulfide treatment. It is a dezincification treatment method for obtaining a residue containing zinc (hereinafter, also referred to as “dezincinated residue”) and a solution containing nickel and cobalt.

This dezincification treatment method will be described in detail later, but can be applied to, for example, a treatment in the dezincification step of the wet smelting process of nickel oxide ore.

Specifically, in the dezincification treatment method according to the present embodiment, the solution after the sulfurization treatment is passed through a filtration device to recover the zinc-containing dezincination residue, and a part of the recovered dezincification residue is used. , Is repeatedly supplied to the reaction vessel (sulfurization reaction tank) containing the initial solution. At that time, the solid amount in the slurry flow rate containing the dezincinated residue repeatedly in the reaction vessel is set to be in the range of 1 g or more and 10 g or less with respect to 1 m ³ of the starting liquid supplied to the reaction vessel. It is supposed to be. The solid content in the residue slurry that is repeatedly supplied to the reaction vessel means a dezincinated residue containing zinc sulfide.

According to such a method, the zinc removal rate before and after passing the liquid through the filtration device can be improved, and the high removal rate can be maintained for stable treatment. Here, the zinc removal rate means the rate at which the zinc concentration in the solution decreases before and after passing the liquid through the filtration device.

For example, when this dezincification treatment method is applied to the dezincification step in the hydrometallurgical process of nickel oxide ore, the zinc removal rate can be effectively improved and stable treatment can be performed. It is possible to reduce the zinc concentration in the nickel recovery mother liquor to be used. As a result, the zinc concentration in the nickel-cobalt mixed sulfide obtained in the nickel recovery step can be effectively reduced, and high quality can be maintained.

In the following, a case where this dezincification treatment method is applied to the dezincification step in the hydrometallurgical process of nickel oxide ore will be described more specifically.

≪2. Room-type smelting process for nickel oxide ore ≫
First, the hydrometallurgical process of nickel oxide ore will be described. FIG. 1 is a process diagram showing an example of the flow of a hydrometallurgical process for nickel oxide ore. A process using a high-pressure acid leaching method (HPAL method) in which a slurry of nickel oxide ore is leached with sulfuric acid under high temperature and high pressure will be exemplified.

As shown in FIG. 1, the wet smelting process of nickel oxide ore is a leaching step S1 in which sulfuric acid is added to a nickel oxide ore slurry (ore slurry) as a raw material and leaching is performed under high temperature pressure to obtain a leaching slurry. In the solid-liquid separation step S2 for separating the leachate residue from the leachate slurry to obtain a leachate containing nickel and cobalt, and the neutralization step S3 for adjusting the pH of the leachate to separate the impurity elements as a neutralized starch slurry. The dezincination step S4 to obtain a nickel recovery mother liquor containing nickel and cobalt by adding a sulfide agent to the nickel recovery mother liquor by adding a sulfide agent using the Japanese final solution as the starting solution, and the sulfide agent to the nickel recovery mother liquor. The nickel recovery step S5, which obtains a mixed sulfide of nickel and cobalt by adding nickel and cobalt.

[Leaching process]
In the leaching step S1, sulfuric acid is added to the ore slurry obtained by crushing and classifying the raw material nickel oxide ore under high temperature and pressure to leach valuable metals such as nickel in the ore. Specifically, in the leaching step S1, sulfuric acid is added to the ore slurry using an autoclave, and the mixture is stirred under conditions of a temperature of about 220 ° C. to 280 ° C. and a pressure of about 3 MPa to 5 MPa, and leaching consisting of a leachate and a leachate residue. Generate a slurry.

Examples of the nickel oxide ore as a raw material mainly include so-called laterite ores such as limonite ore and saprolite ore. The nickel content of the laterite ore is usually 0.8% by weight to 2.5% by weight, and is contained as a hydroxide or a magnesium silicate mineral. The iron content is 10% by weight to 50% by weight, mainly in the form of a trivalent hydroxide, but some divalent iron is contained in the magnesium magnesium mineral.

In the leaching treatment in the leaching step S1, a leaching reaction and a high-temperature hydrolysis reaction occur, and leaching of nickel, cobalt and the like as sulfates and immobilization of the leached iron sulfate as hematite are performed. However, since the immobilization of iron ions does not proceed completely, the liquid portion of the obtained leachate slurry usually contains divalent and trivalent iron ions in addition to nickel, cobalt and the like.

[Solid-liquid separation process]
In the solid-liquid separation step S2, the leachate slurry generated in the leachate step S1 is washed in multiple stages to separate the leachate containing valuable metals such as nickel and cobalt from the leachate residue.

In the solid-liquid separation step S2, for example, the leachate slurry is mixed with the cleaning liquid, and then the solid-liquid separation treatment is performed using a solid-liquid separation device such as a thickener. Specifically, first, the leachate slurry is diluted with a washing liquid, and then the leachate residue in the leachate slurry is concentrated as a thickener sediment. As a result, the nickel content adhering to the leachate residue can be reduced according to the degree of dilution thereof. Further, by solid-liquid separation while performing multi-stage cleaning by using the thickeners connected in multiple stages in this way, it is possible to improve the recovery rate of nickel and cobalt in the cleaning liquid, that is, the leachate.

As a multi-stage cleaning method in the solid-liquid separation treatment, a continuous countercurrent cleaning method (CCD method) in which nickel-free cleaning liquid is used to contact the countercurrent is used. As a result, the amount of cleaning liquid newly introduced into the system can be reduced, and the recovery rate of nickel and cobalt can be increased. As the cleaning liquid, a liquid that does not contain nickel and does not affect the process can be used. Among them, it is preferable to use an aqueous solution having a pH of 1 to 3.

[Neutralization process]
In the neutralization step S3, the pH of the obtained neutralization final solution is 4 or less, preferably 3.0 to 3.5, more preferably 3.1 to 3.2, while suppressing the oxidation of the separated leachate. A neutralizing agent such as calcium carbonate is added to the leachate to generate a neutralizing final solution that is the source of the mother liquor for recovering nickel and a neutralized starch slurry containing trivalent iron as an impurity element. Let me.

In the treatment in the neutralization step S3, a part of the leachate residue separated in the solid-liquid separation step S2 may be added to the leachate to be neutralized. As a result, it is possible to suppress the recovery loss of nickel and cobalt that have migrated into the leaching residue without being leached out.

In the neutralization step S3, impurities such as trivalent iron ions and aluminum ions remaining in the solution are separated and removed as neutralized starch by subjecting the leachate to a neutralization treatment (purification treatment) in this way. .. The odor of the neutralized sol containing iron hydroxide or the like can be separated by using a sedimentation separation device such as a thickener, and a flocculant or a coagulant can be added from the viewpoint of promoting the sedimentation rate.

The neutralization final solution is a solution based on the leachate obtained by performing the leachate treatment with sulfuric acid (leaching step S1), and is a sulfuric acid acidic solution containing nickel and cobalt. This neutralization final solution serves as a reaction starting solution for the sulfide reaction in the dezincification step S4 and the nickel recovery step S5, which will be described later, and the total concentration of the nickel concentration and the cobalt concentration is, for example, 2 g / L to 6 g / L. Is in the range of. In addition, this neutralization final solution may contain iron (III) hydroxide derived from trivalent iron ions that remain without being removed.

[Dezincification process]
In the dezincification step S4, the neutralizing final solution obtained through the neutralization step S3 is used as an initial solution (dezincification initial solution), and a sulfurizing agent such as hydrogen sulfide gas is added to perform sulfurization treatment in the solution. Zinc contained in is separated and removed in the form of sulfide. Hereinafter, this treatment is also referred to as "dezincification treatment".

As described above, the neutralization final solution obtained through the neutralization step S3 contains nickel and cobalt to be recovered, and also contains zinc as an impurity component. In the dezincification step S4, prior to recovering nickel and cobalt from the neutralization final solution, a sulfurization reaction is generated under predetermined conditions to generate zinc sulfide, which is separated and removed to form nickel and cobalt. Obtain a nickel recovery mother liquor containing.

Specifically, in the dezincification step S4, for example, a neutralized final solution containing nickel, cobalt, and zinc is supplied into a pressurized reaction vessel (sulfurization reaction vessel), and hydrogen sulfide is introduced into the gas phase of the reaction vessel. By blowing gas or the like, zinc is selectively sulphurized with respect to nickel and cobalt to generate zinc sulfide and a mother liquor for recovering nickel. Then, the slurry obtained after the sulfurization reaction is solid-liquid separated to obtain a nickel recovery mother liquor from which zinc has been separated.

Also in the nickel recovery step S5 of the next step, a sulfurizing agent such as hydrogen sulfide gas is added to cause a sulfurization reaction to generate a mixed sulfurized product of nickel and cobalt, but prior to the sulfurization treatment of nickel or the like. In the treatment in the dezincification step S4, the conditions for the sulfurization reaction are relaxed compared to the sulfurization reaction conditions for nickel.

Here, in the dezincification treatment in the dezincification step S4, a residue containing zinc sulfide generated by the sulfide reaction (dezincification residue) is separated and recovered, and then a part of the residue is repeatedly added to the reaction vessel. There is. As a result, it is possible to increase the efficiency of producing zinc sulfide and improve the filterability when filtering to separate the residue from the nickel recovery mother liquor.

At this time, the present embodiment is characterized in that the amount of repeated dezincification residue in the system is controlled within a specific range. As a result, the amount of zinc transferred to the obtained nickel recovery mother liquor can be reduced, and the zinc concentration in the nickel-cobalt mixed sulfide obtained in the nickel recovery step S5 of the next step can be stably reduced. .. Details will be described later.

[Nickel recovery process]
In the nickel recovery step S5, the nickel recovery mother liquor obtained through the dezincification step S4 is used as the starting liquid, and a sulfurizing agent such as hydrogen sulfide gas is blown into the starting liquid to cause a sulfurization reaction to cause an impurity component. It produces a small amount of nickel and cobalt sulfide (nickel-cobalt mixed sulfide) and a poor liquid (sulfide final solution) in which the concentration of nickel and cobalt is stabilized at a low level. The nickel recovery mother liquor is a sulfuric acid aqueous solution containing nickel and cobalt.

The sulfurization treatment in the nickel recovery step S5 can be performed using a sulfurization reaction tank or the like as in the treatment in the dezincification step S4, and the reaction with respect to the initial solution in the sulfurization reaction tank adjusted to a predetermined pressure. Hydrogen sulfide gas or the like is blown into the gas phase portion in the tank, and the hydrogen sulfide gas is dissolved in the solution to cause a sulfurization reaction. By this sulfurization treatment, nickel and cobalt contained in the starting liquid are immobilized as sulfides and recovered.

After the completion of the sulfurization reaction, the obtained slurry containing the nickel-cobalt mixed sulfide is charged into a sedimentation separation device such as a thickener and subjected to sedimentation separation treatment, and only the sulfide is separated and recovered from the bottom of the thickener. do. On the other hand, the aqueous solution component overflows from the upper part of the thickener and is recovered as a poor liquid.

≪3. About treatment in dezincification process (dezincification treatment) ≫
As described above, in the dezincification step, the neutralization final solution obtained through the neutralization step S3 is used as the initial solution (dezincification initial solution), and a sulfurizing agent such as hydrogen sulfide gas is added to the dezincification initial solution. By subjecting it to sulfurization treatment, a zinc-containing residue (dezincinated residue) and a solution containing nickel and cobalt (nickel recovery mother liquor) are obtained. More specifically, for example, a neutralized final solution containing at least nickel, cobalt, and zinc is supplied into a pressurized reaction vessel (sulfurization reaction vessel), and hydrogen sulfide gas is supplied into the gas phase of the reaction vessel. By blowing in, zinc is selectively sulfided with respect to nickel and cobalt to form a residue containing zinc sulfide and a mother liquor for recovering nickel.

FIG. 2 is a block diagram showing a configuration of a processing facility in which a dezincification treatment is performed in the dezincification step. In the dezincification treatment facility 1, the neutralization final solution (dezincification initial solution) transferred through the neutralization step S3 is supplied to the sulfurization reaction tank 11, and then hydrogen sulfide gas is supplied to the gas phase portion of the reaction tank 11. Sulfide reaction occurs by blowing in, and zinc sulfide contained in the solution is generated. Subsequently, a slurry containing zinc sulfide (sulfide reaction slurry) is transferred to the relay layer 12 and temporarily stored, and then the slurry is supplied to a filtration device 13 such as a filter press to perform a filtration process. In the filtration device 13, the residue containing zinc sulfide (dezincinated residue) contained in the slurry and the nickel recovery mother liquor are separated.

Here, as described above, a part of the dezincinated residue containing the separated and recovered zinc sulfide is repeatedly added to the sulfurization reaction tank 11. The zinc sulfide in the dezincinated residue repeated in the sulfurization reaction tank 11 acts as a seed crystal of the sulfurization reaction generated in the sulfurization reaction tank 11 and enhances the efficiency of sulfurization of zinc in the starting solution. Further, by adding a seed crystal and reacting, the particle size of the zinc sulfide produced can be controlled, and the filterability in the filtration device 13 can be improved.

In the equipment configuration shown in FIG. 2, “reference numeral 14” indicates an in-system recovery tank, which is a tank for recovering and storing the dezincinated residue that is repeatedly added to the system among the separated and recovered dezincinated residues. .. Further, "reference numeral 15" indicates an extra-system discharge tank, which is a tank for recovering and storing the dezincinated residue discharged to the outside of the system among the separated and recovered dezincinated residues, and the storage of the extra-system discharge tank 15. The dezincinated residue is transferred to a treatment facility that executes a wastewater treatment step and is used for wastewater treatment.

The dezincinated residue recovered by the filtration device 13 in the dezincification treatment facility 1 mainly contains Fe (OH) ₃ and ZnS and FeS. Fe (OH) ₃ is brought in from the neutralization step S3, which is a pre-step of the dezincification step S4, and ZnS and FeS are derived from the precipitation based on the sulfurization reaction due to the addition of hydrogen sulfide gas in the dezincification treatment. Is. Therefore, when the liquid is passed through the filtration device 13, between Zn ²⁺ and ZnS in the slurry to be passed and Fe (OH) ³ and FeS contained in the residue on the filter cloth constituting the filtration device 13. The following two reactions have occurred.
2Fe (OH) ₃ + ZnS + 6H ⁺ = 2Fe 2 ⁺ + Zn 2 ⁺ + S ⁰ + 6H ₂ O
... [Equation 1]
Zn ²⁺ + FeS = Fe ²⁺ + ZnS ... [Equation 2]

In the dezincification treatment that creates a reducing atmosphere, it is considered that the reaction of the above [formula 1] proceeds faster than the reaction of the above [formula 2]. However, since the amount of iron (III) hydroxide brought in from the previous step (neutralization step) and the amount recovered by the filtration device 13 as a dezincinated residue are usually small, the reaction amount is described in the above [Formula 2]. ] Exceeds the reaction of [Equation 1], and it is presumed that the zinc concentration decreases before and after passing the liquid through the filtration device 13.

However, when the amount of the recovered dezincinated residue repeated in the sulfide reaction tank 11 increases, the amount of iron (III) hydroxide brought into the sulfide reaction tank 11 and the amount recovered by the filtration device 13 increase. The reaction amount of the above [Equation 1] at the time of passing the liquid through the filtration device 13 will increase, and the zinc removal rate before and after passing the liquid through the filtration device will decrease.

Therefore, the present inventor repeated diligent studies and repeated the amount of the dezincinated residue recovered by the filtration device 13 for the dezincinated starting liquid amount of 1 m ³ supplied to the sulfide reaction tank 11 (repeated amount in the residue system). ) Is set to a specific range, and it has been found that the zinc removal rate after passing the liquid through the filtration device can be stably maintained at a high level. Specifically, the repeating amount in the residue system is adjusted and maintained in the range of 1 g / m ³ or more and 10 g / m ³ or less.

The zinc removal rate refers to the rate at which the zinc concentration in the solution decreases before and after passing the liquid through the filtration device 13. The repeating amount in the residue system is expressed by the following formula.
Repetition amount in the residue system (g / m ³ ) = [Solid amount in the system repeat flow rate (g / hr)] / [Dezincification starting liquid flow rate (m ³ / hr)]

By adjusting the amount of repetition in the residue system in this way, the zinc removal rate before and after passing the liquid through the filtration device 13 is increased, and the increase in the zinc concentration contained in the filtrate, that is, the nickel recovery mother liquor is suppressed. Can be done. This makes it possible to reduce the risk that the zinc concentration of the nickel-cobalt mixed sulfide (product) obtained by subjecting the nickel recovery mother liquor to sulfurization treatment increases. In addition, by maintaining a high zinc removal rate, it is possible to prevent an increase in the amount of hydrogen sulfide gas, which is a sulfide agent, in order to suppress an increase in the zinc concentration in the nickel-cobalt mixed sulfide. Along with this, it is possible to prevent an increase in nickel (increased nickel loss) that is distributed to the dezincinated residue, and it is possible to carry out a highly efficient operation.

As described above, the amount of repetition in the residue system is adjusted to the range of 1 g / m ³ or more and 10 g / m ³ or less. If the repeating amount in the residue system is less than 1 g / m ³ , the amount of zinc sulfide added to the dezincification starting liquid supplied to the sulfide reaction tank 11 is too small, that is, no seed crystal is present. Therefore, the filterability when filtering the slurry by the filtration device 13 deteriorates. On the other hand, if the repeating amount in the residue system exceeds 10 g / m ³ , the zinc removal rate decreases (see FIG. 3 described in Examples described later).

As described above, in the dezincification treatment method according to the present embodiment, when a part of the dezincination residue obtained by the sulfide treatment is repeatedly supplied to the reaction vessel containing the dezincination starting solution, the residue system is used. The amount of internal repetition, that is, the amount of solid in the flow rate of the slurry containing the dezincinated residue repeated in the sulfide reaction tank 11, is in the range of 1 g or more and 10 g or less with respect to 1 m ³ of the dezincination starting solution supplied to the sulfide reaction tank 11. It is adjusted so as to.

According to such a method, it is possible to improve the zinc removal rate before and after passing the liquid through the filtration device 13 without making a large capital investment, and to maintain the high removal rate for stable treatment. It is possible to reduce the zinc concentration in the nickel-cobalt mixed sulfide obtained through the dezincification final liquid and the nickel recovery step S5, and to facilitate the management. This method greatly contributes to economic operation and its industrial value is extremely high.

Hereinafter, examples of the present invention will be described in more detail, but the present invention is not limited to the following examples.

[Example]
A hydrometallurgical process of nickel oxide ore was carried out according to the flow chart shown in FIG. Then, in the dezincification step, the neutralizing final solution obtained through the neutralization step is supplied to the sulfurization reaction vessel (reaction tank) as the initial solution (dezincination initial solution), and the internal pressure of the vessel is maintained at 0.02 MPa. As described above, hydrogen sulfide gas as a sulfide agent was blown into the gas phase portion to generate a residue containing zinc sulfide (dezincinated residue). The final solution of neutralization was continuously supplied to the sulfurization reaction vessel, and the reaction was carried out while stirring while maintaining the liquid temperature at 55 ° C.

Next, the solution containing the obtained dezincinated residue was transferred to a filter press, which is a filtration device, and the dezincinated residue was separated. In the dezincinated residue containing the separated zinc sulfide, a part was repeated in the sulfurization reaction vessel in the form of a slurry, and the rest was recovered.

At this time, when the slurry containing the dezincinated residue is repeatedly added to the sulfide reaction vessel, the amount of solid in the slurry flow rate is in the range of 1 g or more and 10 g or less with respect to 1 m ³ of the dezincinated starting liquid supplied to the sulfide reaction vessel. The operation was carried out for 24 hours. The repeated amount of the dezincinated residue with respect to 1 m ³ of the dezincinated starting solution was defined as the "repeated amount in the residue system".
Repetition amount in the residue system (g / m ³ ) = [Solid amount in the system repeat flow rate (g / hr)] / [Dezincification starting liquid flow rate (m ³ / hr)]

Table 1 below shows the results of 24-hour operation under the conditions of the above-mentioned examples. Further, FIG. 3 is a graph showing the results of several operation examples in which the repeating amount in the residue system is in the range of 1 g / m ³ or more and 10 g / m ³ or less. Here, the value of the repetition amount in the residue system in Table 1 is an average value of operating examples in the range of 1 g / m ^{3 or more and 10 g / m 3 or} less shown in the graph of FIG.

The "zinc removal rate (%)" in Table 1 refers to the rate at which the zinc concentration in the solution decreases before and after the liquid is passed through the filtration device, and is filtered with respect to the amount of zinc in the solution before the liquid is passed through the filtration device. Percentage of the amount of zinc removed by the device.

The "nickel precipitation rate (%)" in Table 1 refers to the nickel content contained in the dezincinated residue separated by the dezincification treatment, and is represented by the following formula.
Nickel precipitation rate (%) = 100-Nickel concentration in nickel recovery mother liquor / Nickel concentration in neutralization final solution x 100

The "product zinc concentration (ppm)" in Table 1 is based on the dezincified final solution (solution obtained after passing through the filtration device) obtained by the dezincification treatment, and undergoes the nickel recovery step of the next step. Zinc concentration in the recovered nickel-cobalt mixed sulfide (product).

The results of the nickel precipitation rate and the product zinc concentration show the average value of the results of a plurality of operation examples in which the repetition amount in the residue system shown in FIG. 3 is in the range of 1 g / m ³ or more and 10 g / m ³ or less. ing. The zinc removal rate indicates the average, maximum, and minimum of the multiple operation examples.

[Comparative Example 1]
In the comparative example, in the dezincification step, the repetition amount in the residual system was repeated so as to be in the range of 11 g or more and 96 g or less with respect to 1 m ³ of the dezincination starting solution, and the operation was carried out for 24 hours. Other than this, the operation was performed in the same manner as in Example 1.

Table 2 below shows the results of 24-hour operation under the conditions of the comparative example. In addition, the graph of FIG. 3 also shows the results of several operation examples in which the repeating amount in the residue system is in the range of 11 g / m ³ or more and 96 g / m ³ or less. The definition of each item in Table 2 is the same as that in Table 1.

[result]
As shown in Table 1, in the example in which the operation was performed by adjusting the repetition amount in the residue system in the dezincification treatment to the range of 1 g / m ³ to 10 g / m ³ , zinc was removed before and after filtration by the filtration device. The rate changed at a high rate of 76% to 91%, and the average was 81%, and zinc could be effectively removed. In addition, the zinc precipitation rate in the dezincinated residue is as low as 1.03% on average, and the zinc concentration of the products produced during the period is 109 ppm on average, which does not exceed the standard concentration (250 ppm) and is a high quality product. Was able to produce.

On the other hand, as shown in Table 2, in the comparative example in which the operation was performed by adjusting the repeating amount in the residue system in the dezincification treatment to the range of 11 g / m ³ to 96 g / m ³ , the zinc removal rate before and after filtration. However, it remained at a low rate of -41% to 71%, and the average was 39%, which was extremely low. The nickel precipitation rate in the dezincinated residue was 1.42% on average, and more nickel was distributed in the residue together with zinc as compared with the examples, resulting in loss.

Further, in the comparative example, the zinc concentration of the products produced within the period was 173 ppm on average, and some products exceeded the standard concentration (250 ppm). Therefore, in order to improve the product quality, the amount of hydrogen sulfide gas added to cause the sulfurization reaction was increased. As a result, the hydrogen sulfide addition equivalent during the operation of the comparative example was 4.02 on average, which was higher than the average 3.54 of the hydrogen sulfide addition equivalent during the operation of the example. As described above, in the comparative example, the amount of hydrogen sulfide gas used increased, so that the operating cost increased.

The hydrogen sulfide addition equivalent is defined as follows.
Hydrogen sulfide addition equivalent = [Hydrogen sulfide blown amount (m ³ / h)] / [[Inflow zinc amount (kg / h)] / [Zinc atomic weight (g / mol) x 22.4 (L / mol)]

1 Dezincification treatment equipment 11 Sulfurization reaction tank (reaction tank)
12 Relay tank 13 Filtration device 14 Internal recovery tank 15 External discharge tank

Claims (3)

A solution containing nickel, cobalt, and zinc is used as the starting solution, and a sulfurizing agent is added to the starting solution to perform sulfurization treatment to obtain a residue containing zinc sulfide and a solution containing nickel and cobalt. In the dezincification treatment method
The solution after the sulfurization treatment was passed through a filtration device to recover the zinc sulfide-containing residue, and a part of the recovered residue was repeatedly added to the reaction vessel containing the initial solution.
At that time , the reaction vessel is repeated so that the amount of the residue is in the range of 1 g or more and 10 g or less with respect to 1 m ³ of the starting liquid supplied to the reaction vessel.
Dezincification treatment method. The starting liquid contains trivalent iron and is contained in the residue as iron (III) hydroxide by the sulfurization treatment.
The dezincification treatment method according to claim 1. A leachation step of acid leaching a slurry of nickel oxide ore to obtain a leachate containing nickel and cobalt, a neutralization step of neutralizing the obtained leachate to remove impurities, and neutralization after the neutralization treatment. A dezincification step of producing and separating zinc sulfide contained in the neutralized final solution by adding a sulfurizing agent to the final solution as a dezincifying final solution and performing a sulfurization treatment, and a sulfide agent in the dezincinated final solution. It is a hydrometallurgical method for nickel oxide ore having a nickel recovery step of producing and recovering a mixed sulfide of nickel and cobalt by adding zinc oxide.
In the dezincification step, a sulfurizing agent is added to a reaction vessel containing the dezincination starting liquid to perform sulfurization treatment, and a part of the residue containing zinc sulfide recovered by passing the liquid through a filtration device is subjected to the reaction. Repeatedly add to the container,
At that time , the reaction vessel is repeated so that the amount of the residue is in the range of 1 g or more and 10 g or less with respect to the dezincination starting liquid amount of 1 m ³ supplied to the reaction vessel.
Hydrometallurgical method for nickel oxide ore.

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