JP7005909B2 - Neutralization treatment method and turbidity reduction method of neutralization final liquid - Google Patents

Description

The present invention relates to a neutralization treatment method, and more particularly, a neutralization treatment method in a neutralization step of wet smelting of nickel oxide ore, which effectively reduces the turbidity of the obtained neutralization final solution. The present invention relates to a neutralization treatment method capable of allowing the neutralization to occur, and a method for reducing the turbidity of the neutralization final liquid.

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

This high pressure acid leaching method includes, for example, the following steps. That is,
(A) A leaching step in which sulfuric acid is added to a nickel oxide ore slurry and leached under high temperature and high pressure to obtain a leaching slurry consisting of a leaching solution and a leaching residue.
(B) A solid-liquid separation step of separating the leachate residue while washing the leachate slurry in multiple stages to obtain a leachate containing an impurity element together with nickel and cobalt.
(C) A neutralization step of separating a neutralized starch containing an impurity element by adding a neutralizing agent to the leachate to adjust the pH to obtain a neutralized final solution containing nickel and cobalt.
(D) When the neutralization final solution contains a large amount of zinc, a dezincification step of removing zinc as a sulfide by adding hydrogen sulfide gas to obtain a dezincification final solution, and
(E) Hydrogen sulfide gas is added to the mother liquor (neutralization final solution or dezincification final solution) for nickel recovery to generate sulfide containing nickel and cobalt, and the nickel-cobalt mixed sulfide is separated from others. Includes a nickel recovery step.

Specifically, in the neutralization step, the leachate recovered through the solid-liquid separation step is charged into a neutralization tank and neutralized by adding a neutralizing agent such as a calcium carbonate slurry to neutralize the obtained hydroxide. By solid-liquid separation of the precipitate, a neutralized starch and a neutralized final solution are obtained. However, this solid-liquid separation treatment was difficult, and it was unavoidable that fine neutralized starch was mixed into the neutralized final solution. When the neutralized starch is mixed in this way, the neutralized final liquid becomes highly turbid and impurities are brought into the subsequent process.

By the way, for example, in Patent Document 1, in order to promote the process of fixing and separating zinc as sulfide in the dezincination step for removing zinc contained in the neutralization final solution obtained by the above-mentioned neutralization step. , A technique for maintaining the turbidity of the neutralized final liquid at a high level and treating the solution has been proposed. This makes it possible to coarsen the neutralized starch with zinc sulfide to improve the filterability and increase the nickel recovery rate.

However, for example, when the method described in Patent Document 1 is used, if the conditions of the neutralization step and the dezulfization step are not properly combined according to the amount of impurities, the mother liquor for recovering nickel obtained through the dezulfization step can be obtained. Is likely to have a large amount of impurities remaining, and when nickel-cobalt mixed sulfide is produced by sulfurization treatment using such a nickel recovery mother liquor (sulfurization reaction starting solution), the mixed sulfide contains a large amount of impurities. There is a problem of being lost.

As described above, in the neutralization final liquid which is the reaction start liquid of the sulfurization reaction in the nickel recovery step, the turbidity affects the impurity content of the obtained nickel-cobalt mixed sulfurized product. Therefore, in the neutralization step, it is required to effectively precipitate impurities in the leachate and to stably maintain the turbidity of the neutralization final liquid sent to the next step at a low level.

Japanese Unexamined Patent Publication No. 2010-37626

The present invention has been proposed in view of such circumstances, and can effectively remove impurities in the leachate as a precipitate in the neutralization treatment in the hydrometallurgical process of nickel oxide ore. It is an object of the present invention to provide a method capable of reducing the turbidity of the neutralizing final liquid to be sent to the next step.

As a result of repeated diligent studies, the present inventor adjusted the pH to a predetermined range by adding a neutralizing agent to the leachate in the neutralization treatment, and added the leachate residue slurry at a specific ratio to neutralize the final solution. We have found that the above-mentioned problems can be solved by setting the turbidity of the above-mentioned material to less than 100 NTU, and have completed the present invention.

(1) In the first invention of the present invention, a nickel oxide ore is leached with an acid to obtain a leached slurry containing a leached liquid and a leached residue, and then the leached slurry is solid-liquid separated and recovered. A neutralization treatment method in which a neutralizing agent is added to the leachate to neutralize the leachate to obtain a neutralizing starch containing impurities and a neutralizing final solution containing nickel and cobalt, which is neutralized with the leachate. The neutralization final solution obtained by adding an agent to adjust the pH in the range of 2.5 to 3.5 and adding the slurry of the leachate residue obtained by solid-liquid separation of the leachate slurry. It is a neutralization treatment method that makes the turbidity less than 100 NTU.

(2) In the second invention of the present invention, in the first invention, the leachate residue slurry is subjected to the neutralization treatment from 7.0% by volume to 16.0 with respect to the flow rate of the leachate (starting liquid). It is a neutralization treatment method of adding to the leachate at a flow rate of a volume%.

(3) The third aspect of the present invention is the neutralization treatment method for adjusting the temperature of the leachate to 55 ° C. to 70 ° C. in the first or second invention.

(4) In the fourth aspect of the present invention, in any one of the first to third inventions, the leachate residue slurry has a slurry concentration of 1.5 t / m ³ to 1.7 t / m ³ . It is a sum processing method.

(5) The fifth aspect of the present invention is the neutralization treatment method in which the coagulant is also added when the leachate residue slurry is added in any one of the first to fourth inventions.

(6) The sixth invention of the present invention is obtained by solid-liquid separation of the leaching residue slurry in any one of the first to fifth inventions while washing the leaching slurry in multiple stages. It is a neutralization treatment method.

(7) In the seventh invention of the present invention, a nickel oxide ore is leached with an acid to obtain a leached slurry containing a leaching solution and a leaching residue, and then the leaching slurry is washed in multiple stages for solid-liquid separation. This is a method for reducing the turbidity of the neutralized final solution from which the neutralized starch containing impurities is removed, which is obtained by adding a neutralizing agent to the recovered leachate and performing a neutralization treatment. In the treatment, a neutralizing agent is added to the leachate to adjust the pH to the range of 2.5 to 3.5, and the slurry of the leachate residue that has been multi-stage washed and solid-liquid separated is added. This is a method for reducing the turbidity of the neutralized final liquid so that the turbidity of the obtained neutralized final liquid is less than 100 NTU.

According to the present invention, in the neutralization treatment of nickel oxide ore in the hydrometallurgical process, impurities in the leachate can be effectively removed as a precipitate, and a neutralized final liquid having reduced turbidity can be obtained. can. By using the neutralized final solution with reduced turbidity in this way to generate sulfides containing nickel and cobalt by a sulfurization reaction, it is possible to obtain sulfides with extremely low impurity content, resulting in product quality. Can be improved. Therefore, such a neutralization treatment method has extremely high industrial value.

It is a process diagram which shows an example of the flow of the wet smelting process of nickel oxide ore. It is a graph which shows the result of having investigated the transition of the turbidity of a neutralizing final liquid based on the difference in the ratio of the addition flow rate of the leachate residue slurry to the flow rate of the leachate (starting liquid) subjected to the neutralization treatment. It is a graph which shows the result of having investigated the relationship of the turbidity reduction rate based on the difference in the ratio of the addition flow rate of the leachate residue slurry to the flow rate of the leachate (starting liquid) to be neutralized.

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. Outline of neutralization treatment method ≫
The neutralization treatment method according to the present embodiment is a method of neutralization treatment in the neutralization step in the wet smelting process of nickel oxide ore (hereinafter, also simply referred to as “wet smelting process”).

Specifically, the neutralization treatment in the hydrometallurgical process is included in the leachate by adding a neutralizing agent to the leachate obtained by the acid leaching treatment for nickel oxide ore to adjust the pH to a predetermined range. This is a process of obtaining a neutralized final solution from which the impurities are removed as a precipitate (neutralized starch). In the hydrometallurgical process of nickel oxide ore, the neutralized final solution obtained by the treatment in such a neutralization step is used as a mother liquor for recovering nickel, and nickel and cobalt are recovered as sulfides.

The neutralization treatment method according to the present embodiment is carried out in the neutralization step in the hydrometallurgical process of nickel oxide ore described above, and a neutralizing agent is added to the leachate containing nickel and cobalt. The neutralization final solution obtained by adjusting the pH to the range of 2.5 to 3.5 and adding the slurry of the leachate residue obtained by solid-liquid separation of the leachate slurry obtained by the leachate treatment. It is characterized in that the turbidity of the above is less than 100 NTU.

According to such a method, the turbidity of the obtained neutralized final liquid can be maintained in a low state, and a nickel-cobalt mixed sulfurized product having less impurities is produced in the sulfurization step after the wet smelting process. Can be made to. The mixed sulfide having a low content of impurities has extremely excellent product quality, and the industrial value of this neutralization treatment method is extremely high.

≪2. Wet smelting process of nickel oxide ore ≫
First, prior to a more specific description of the neutralization treatment method, a hydrometallurgical process of nickel oxide ore including a neutralization step to which this treatment method is applied will be described.

FIG. 1 is a process diagram showing an example of the flow of a hydrometallurgical process for nickel oxide ore. As shown in FIG. 1, the hydrometallurgical process consists of a leaching step S1 in which sulfuric acid is added to a slurry of nickel oxide ore as a raw material and a leaching treatment is performed under high temperature and high pressure, and a leaching residue is separated from the leaching slurry to obtain nickel. And a solid-liquid separation step S2 to obtain a leachate containing cobalt, a neutralization step S3 to adjust the pH of the leachate and separate impurities in the leachate as neutralizing starch to obtain a neutralizing final solution, and a neutralizing final solution. It has a sulphurization step S4 for producing a mixed sulfide of nickel and cobalt by adding a sulphurizing agent to the mixture.

(1) Leaching step In the leaching step S1, a high-temperature pressure reaction tank such as an autoclave is used, sulfuric acid is added to a slurry of nickel oxide ore (hereinafter, also referred to as “ore slurry”), and the temperature is about 230 ° C to 270 ° C. A leach slurry composed of a leachate and a leachate residue is produced by stirring under the condition of a pressure of about 3 MPa to 5 MPa.

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. Further, in the leaching step S1, in addition to such laterite ore, an oxide ore containing a valuable metal such as nickel, cobalt, manganese, and copper, for example, a manganese aneurysm endowed on the deep sea bottom can be used.

In the leaching treatment in the leaching step S1, for example, a leaching reaction represented by the following formulas (a) to (e) and a high-temperature hydrolysis reaction occur, and leaching of nickel, cobalt and the like as sulfates and leaching iron sulfate are carried out. Immobilization as hematite is 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. In the leachate step S1, the pH of the obtained leachate is adjusted to 0.1 to 1.0 from the viewpoint of the filterability of the leachate residue containing hematite separated in the solid-liquid separation step S2 of the next step. It is preferable to do so.

・ Leachation reaction MO + H ₂ SO ₄ ⇒ MSO ₄ + H ₂ O ・ ・ (a)
(Note that M in the formula represents Ni, Co, Fe, Zn, Cu, Mg, Cr, Mn, etc.)
2Fe (OH) ₃ + 3H ₂ SO ₄ ⇒ Fe ₂ (SO ₄ ) ₃ + 6H ₂ O ... (b)
FeO + H ₂ SO ₄ ⇒ FeSO ₄ + H ₂ O ... (c)
・ High temperature hydrolysis reaction 2 FeSO ₄ + H ₂ SO ₄ + 1 / 2O ₂ ⇒ Fe ₂ (SO ₄ ) ₃ + H ₂ O ・ ・ (d)
Fe ₂ (SO ₄ ) ₃ + 3H ₂ O ⇒ Fe ₂ O ₃ + 3H ₂ SO ₄ ... (e)

The amount of sulfuric acid added to the autoclave charged with the ore slurry is not particularly limited, but an excess amount such that iron in the ore is leached is used. For example, the ratio is 300 kg to 400 kg per ton of ore.

(2) Solid-Liquid Separation Step In the solid-liquid separation step S2, the leachate slurry generated in the leachation 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, 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 sediment of thickener. 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.

The cleaning liquid is not particularly limited, but a nickel-free solution that 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. When the pH of the cleaning liquid is high, bulky aluminum hydroxide is generated when aluminum is contained in the leachate, which causes poor sedimentation of the leachate residue in the thickener. As the cleaning liquid, preferably, a poor liquid having a low pH (pH of about 1 to 3) obtained in the sulfurization step S4, which is a subsequent step, can be repeatedly used.

As a solid-liquid separation device, for example, a thickener provided with an overflow portion for discharging the supernatant liquid at the peripheral portion, a settling separation tank having a tubular feed well arranged vertically in the central portion, and a stirring tank. Can be used. This thickener is provided in multiple stages, and the leachate residue, which is a solid content, is separated and removed while the slurry to be treated is washed in multiple stages.

(3) Neutralization Step In the neutralization step S3, while suppressing the oxidation of the leachate, a neutralizing agent is added to the obtained leachate to adjust the pH to a predetermined range, and the neutralized starch containing an impurity element is used. It produces a neutralized final solution that serves as a mother liquor for recovering nickel.

Specifically, in the neutralization step S3, a neutralizing agent is added to the leachate so that the pH of the obtained neutralization final solution is in the range of 2.5 to 3.5, and the neutralization final solution and impurities are added. It forms a neutralized starch slurry containing, for example, trivalent iron as an element. In the neutralization step S3, by performing the neutralization treatment on the leachate in this way, the excess acid used in the leachation treatment in the leachation step S1 is neutralized to generate a neutralized final liquid, and the solution is added to the solution. Residual impurity elements such as iron ions and aluminum ions are removed as neutralized starch. The recovered neutralized starch can be repeatedly added to the solid-liquid separation step S2.

Here, in the present embodiment, in this neutralization treatment, a neutralizing agent is added to adjust the pH in the range of 2.5 to 3.5, and the leaching slurry is leached out by solid-liquid separation. Add the residue slurry. As will be described in detail later, by adjusting the pH in this way, adding the slurry of the leachate residue, and adjusting the amount of the addition, the impurity elements can be effectively precipitated and precipitated, and the resulting neutralization can be obtained. The turbidity of the final liquid can be less than 100 NTU. In other words, the turbidity can be stably maintained at a low state while effectively producing neutralized starch and removing impurity elements.

(4) Sulfurization step In the sulfurization step S4, a neutralization final solution which is a mother liquor for recovering nickel and cobalt is used as a sulfurization reaction initial solution, and hydrogen sulfide gas as a sulfurizing agent is blown into the sulfurization reaction initial solution to cause a sulfurization reaction. Is generated, and a mixed sulfurized product of nickel and cobalt having a small amount of impurity components and a sulfurization reaction final liquid which is a poor liquid in which the concentration of nickel and cobalt is stabilized at a low level are produced.

When zinc is contained in the neutralization final solution, zinc can be selectively separated as a sulfide prior to separating nickel or cobalt as a sulfide.

The sulfurization treatment in the sulfurization step S4 can be performed using a sulfurization reaction tank or the like, and hydrogen sulfide gas is blown into the gas phase portion of the sulfurization reaction starting solution introduced into the sulfurization reaction tank to form a solution. The hydrogen sulfide gas that has moved inside can slowly cause a sulfurization reaction. By this sulfurization treatment, nickel and cobalt contained in the sulfurization reaction starting liquid are immobilized as a mixed sulfurized product.

After the completion of the sulfurization reaction, the obtained slurry containing the nickel-cobalt mixed sulfide is charged into a filtration device such as a filter press and subjected to a filtration treatment, and the mixed sulfide is collected on a filter cloth. The aqueous solution component that has passed through the filter cloth is recovered as a poor liquid. In order to reduce the amount of liquid passing through the filtration device, it is preferable to charge the slurry in a sedimentation and concentrating device such as a thickener in advance to remove the supernatant liquid as a poor liquid.

In the present embodiment, as will be described in detail later, in the neutralization treatment in the neutralization step S3, a neutralizing agent is added to adjust the pH to a predetermined range, and a leachate residue slurry is added to the medium. The treatment is performed so that the turbidity of the final solution is less than 100 NTU. By using the neutralization final solution (nickel recovery mother liquor) obtained by such neutralization treatment with effectively reduced turbidity as the sulfurization reaction starting solution in the sulfurization step S4, the impurity content is extremely high. A small amount of nickel-cobalt mixed sulfide can be produced.

≪3. About neutralization treatment in the neutralization process ≫
As described above, in the neutralization treatment in the neutralization step S3 of the hydrometallurgical process, a neutralizing agent is added to the leachate obtained by solid-liquid separation of the leachate slurry produced in the leachation step S1. The pH of the obtained neutralized final solution should be in the range of 2.5 to 3.5. Further, in this neutralization treatment, the pH of the neutralized final solution is adjusted and the slurry of the leachate residue obtained by solid-liquid separation of the leachate slurry is added to the leachate. The turbidity should be less than 100 NTU.

(About pH adjustment)
In this neutralization treatment, the pH of the obtained neutralization final solution is adjusted to be in the range of 2.5 to 3.5 by adding a neutralizing agent to the leachate.

If the pH of the neutralized final solution is adjusted to be less than 2.5, the impurity elements contained in the leachate cannot be sufficiently converted into a precipitate such as a hydroxide. As a result, the impurity content of the obtained neutralization final liquid increases, and the impurity content of the nickel-cobalt mixed sulfurized product produced in the sulfurization step of the next step increases. On the other hand, if the pH of the neutralized final solution is adjusted to exceed 3.5, fine particles having poor sedimentation property are generated and the turbidity tends to increase. In addition, when zinc is removed as a sulfide in a subsequent step, a part of nickel and cobalt also precipitates.

The neutralizing agent is not particularly limited, and for example, an alkali metal hydroxide salt such as magnesium hydroxide or calcium carbonate, an aqueous solution of the alkali metal carbonate, or a slurry can be used. Industrially, it is preferable to use an inexpensive calcium carbonate slurry.

(Reduction of turbidity by adding leachate residue slurry)
In this neutralization treatment, the pH is adjusted to a predetermined range by adding a neutralizing agent, and the neutralization final liquid obtained by adding the slurry of the leachate residue obtained by solid-liquid separation of the leachate slurry is added. The turbidity of the is less than 100 NTU.

In the measurement of the turbidity of the neutralized final liquid, it can be measured using an apparatus compliant with ISO7027 and USEPA180.1 standards. The turbidity is measured, for example, once every 10 minutes to once every 24 hours, preferably about once an hour.

The leaching residue slurry is a slurry of leaching residue obtained by solid-liquid separation of the leaching slurry produced in the leaching step S1 of the hydrometallurgical process in the solid-liquid separation step S2, for example, while performing multi-stage washing. This leachate residue contains hematite (Fe ₂ O ₃ ) as a main component (usually 50% by mass to 70% by mass) and has a large specific gravity.

As described above, in the neutralization treatment for the leachate, by adding the leachate residue slurry, the neutralized starch is aggregated and formed with the leachate residue having a large specific gravity as the nucleus, and as a result, the neutralized starch is settled. The properties can be enhanced, and the turbidity of the obtained neutralized final liquid can be effectively reduced.

The leaching residue slurry is the solid side (slurry having a high solid content) obtained by solid-liquid separation of the leaching slurry obtained in the leaching step S1 while performing multi-stage washing in the solid-liquid separation step S2. Is preferable. The leachate residue obtained by multi-stage washing in this way has little adhesion of acids and alkalis. Therefore, it does not interfere with the control of the overall pH, and the local pH in the vicinity of the added leachate residue also follows the change in the pH of the bulk, so that the precipitation rate and particle size of the neutralized starch are controlled. Becomes easier. In addition, the solid-liquid separated product while being washed in multiple stages has excellent properties of specific gravity separation with water and filtration separation. By selecting and using a particularly strong exudate residue of this property (eg, the bottom of the thickener or the initial precipitate), the neutralized starch can be separated more easily and the turbidity of the neutralized final solution can be reduced. It can be reduced more efficiently.

When adding the leachate residue slurry, the flow rate is preferably 7.0% by volume to 16.0% by volume with respect to the flow rate (starting liquid flow rate) of the leachate (starting liquid) to be subjected to the neutralization treatment. It is added to the leachate at a flow rate of 10.0% by volume to 15.5% by volume, more preferably at a flow rate of 11.8% by volume to 15.3% by volume. In this way, by adding the leachate residue slurry at a flow rate within the above-mentioned range with respect to the initial liquid flow rate, the turbidity of the obtained neutralized final liquid can be more effectively reduced to less than 100 NTU, and even more preferably. Can be reduced to less than 70 NTU.

FIG. 2 shows the turbidity of the neutralizing final liquid based on the difference in the ratio of the addition flow rate of the leachate residue slurry obtained by solid-liquid separation of the leachate slurry to the flow rate of the leachate (starting liquid) subjected to the neutralization treatment. It is a graph which shows the result of having investigated the transition of. Further, FIG. 3 is a graph showing the results of investigating the relationship of the turbidity reduction rate based on the difference in the addition flow rate ratio of the leachate residue slurry.
Addition ratio of leaching residue slurry (% by volume) = leaching residue slurry flow rate / starting liquid flow rate x 100
Turbidity reduction rate (%) = (turbidity of starting liquid-turbidity of neutralized final liquid) / turbidity of starting liquid x 100

In this investigation test, the starting liquid used for the neutralization treatment had a nickel concentration of 3.7 g / L to 4.4 g / L, a cobalt concentration of 0.24 g / L to 0.45 g / L, and an iron concentration. : 0.4 g / L to 1.8 g / L, zinc concentration: 0.07 g / L to 0.12 g / L, and a pH of 2.5 to 3.0 were used. The leachate residue slurry was obtained by solid-liquid separation of the leachate slurry while being washed in multiple stages, and had a nickel grade of 0.1% by mass or less, a cobalt grade of 0.01% by mass or less, and an iron grade. : A composition having a composition of 50% by mass or more and a zinc grade: 0.02% by mass or less was used. In addition, Polydadomac diluted 5-fold was used as a coagulant and added in an amount of 0.047% by volume to 0.051% by volume with respect to the starting solution of the neutralization treatment.

As can be seen from the graphs of FIGS. 2 and 3, the turbidity of the obtained neutralized final liquid is effectively reduced by increasing the addition flow rate of the leachate residue slurry with respect to the flow rate of the leachate which is the starting liquid. Can be made to. It is considered possible to further reduce the turbidity by further increasing the addition ratio of the leachate residue slurry, and the addition ratio is in the range of 7.0% by volume to 16.0% by volume. Is preferable. When the addition ratio is further increased, the load on the equipment such as the pump increases due to the increase in the amount of the leachate residue slurry added and supplied with respect to the degree of reduction in turbidity, and the amount of the coagulant used also increases. there's a possibility that.

Further, as the leachate residue slurry to be added to the leachate, as described above, the slurry obtained by solid-liquid separation while performing multi-stage washing in the solid-liquid separation step S2 is preferable. Further, it is preferable to use a slurry whose slurry concentration is adjusted in the range of 1.5 t / m ³ to 1.7 t / m ³ . By using the leachate residue slurry adjusted to such a slurry concentration, the turbidity of the neutralized final liquid obtained through the neutralization treatment can be more effectively reduced.

Further, when adding the leachate residue slurry, it is preferable to add a coagulant together. In general, it is known that neutralized sediments such as hydroxide precipitates have extremely poor sedimentation properties, and by adding a leachate residue slurry which is a mother of aggregation, and also by adding a coagulant. , The leachate residue slurry having a large specific gravity and the neutralized sediment such as hydroxide precipitate can be condensed to further promote the sedimentation property. As described above, the presence of the leachate residue slurry, which is a mother body that condenses with a neutralized starch such as hydroxide precipitate, can enhance the effect of the coagulant.

The coagulant is not particularly limited, but for example, polyamine, polydadomac, polyethyleneimine, polyacrylamide and the like can be used.

When the flow rate of the leachate increases or decreases, it is preferable to increase or decrease the amount of the leachate residue slurry added accordingly. However, when increasing the addition flow rate of the leachate residue slurry, it is desirable to gradually increase it. Since the leachate residue is effective only when it condenses with the neutralized sol, the neutralized sol may settle even if the addition amount is increased, depending on the composition of the neutralized sol and the amount of the coagulant or flocculant added. This is because it does not promote and may be disadvantageous in terms of residence time.

(About temperature adjustment)
Further, in this neutralization treatment, it is preferable to adjust and maintain the temperature (liquid temperature) of the leachate which is the starting liquid of the neutralization treatment within a specific range. Specifically, it is preferable to adjust the temperature of the leachate to the range of 55 ° C to 70 ° C, and more preferably to adjust it to the range of 60 ° C to 68 ° C. As described above, the turbidity of the obtained neutralized final liquid can be more effectively reduced by performing the neutralization treatment in a state where the temperature of the leachate is adjusted and maintained at 55 ° C to 70 ° C.

When the temperature of the leachate is less than 55 ° C., even if the turbidity of the neutralized final liquid can be reduced to less than 100 NTU by the above-mentioned neutralization treatment, the turbidity reduction rate is small and efficient treatment is performed. May not be possible. On the other hand, even if the temperature of the leachate exceeds 70 ° C, the effect of reducing the turbidity of the neutralized final liquid does not improve further, and the heat energy for adjusting and maintaining the liquid temperature exceeding 70 ° C increases, resulting in cost. It leads to an increase.

The method for adjusting the temperature of the leachate is not particularly limited, and for example, it can be performed by using a high-temperature heat medium and adjusting the flow rate of the high-temperature heat medium. As the high temperature heat medium, it is preferable to use steam having a relatively high safety. Further, the temperature can be adjusted by using a heater or the like.

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

<Neutralization treatment>
[Example 1]
In the neutralization step in the wet smelting process of nickel oxide ore, a slurry of calcium carbonate is added as a neutralizing agent to the leachate so that the pH of the neutralizing final solution is in the range of 2.5 to 3.5. At the same time, the leachate residue slurry was added at a flow rate of 7.9% by volume with respect to the flow rate of the neutralization treatment starting liquid (leachate, also simply referred to as "starting liquid") to perform the neutralization treatment. .. The temperature of the leachate was adjusted and maintained at 55 ° C.

The leachate, which is the starting solution for the neutralization treatment, has a nickel concentration of 3.7 g / L to 4.4 g / L, a cobalt concentration of 0.24 g / L to 0.45 g / L, and an iron concentration of 0.4 g / L to. The one having a composition of 1.8 g / L and a zinc concentration: 0.07 g / L to 0.12 g / L and a pH of 2.5 to 3.0 was used. The leaching residue slurry was obtained by solid-liquid separation of the leaching slurry obtained in the leaching step of the hydrometallurgical process while performing multi-stage washing, and was obtained by nickel grade: 0.1% by mass or less, cobalt. Grade: 0.01% by mass or less, iron grade: 50% by mass or more, zinc grade: 0.02% by mass or less were used. In the neutralization treatment, when the leachate residue slurry was added, Polydadomac diluted 5-fold was used as a coagulant, and the ratio was 0.047% by volume to 0.051% by volume with respect to the starting solution of the neutralization treatment. Was added in the amount of addition.

The turbidity of the neutralized final liquid obtained by the reaction of such a neutralization treatment was measured using a turbidity measuring device (TB1000W, manufactured by Eutech) and found to be 84 NTU. In addition, the impurity load of the neutralized final solution was reduced by 76% with respect to the initial solution.

[Example 2]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 7.4% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 64 NTU. In addition, the impurity load of the neutralized final solution was reduced by 84% with respect to the initial solution.

[Example 3]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 11.8% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 52 NTU. In addition, the impurity load of the neutralized final solution was reduced by 90% with respect to the initial solution.

[Example 4]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 13.2% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 61 NTU. In addition, the impurity load of the neutralized final solution was reduced by 85% with respect to the initial solution.

[Example 5]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 15.3% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 41 NTU. In addition, the impurity load of the neutralized final solution was reduced by 90% with respect to the initial solution.

[Example 6]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 14.8% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 48 NTU. In addition, the impurity load of the neutralized final solution was reduced by 89% with respect to the initial solution.

[Example 7]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 14.5% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 48 NTU. In addition, the impurity load of the neutralized final solution was reduced by 86% with respect to the initial solution.

[Reference Example 1]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 5.6% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralization final solution obtained by the reaction of such a neutralization treatment was measured and found to be 120 NTU, and the turbidity could not be sufficiently reduced. The impurity load of the neutralized final solution was reduced by 81% with respect to the initial solution.

[Reference Example 2]
In the neutralization treatment, the leaching residue slurry was treated in the same manner as in Example 1 except that the leached residue slurry was added at a flow rate of 6.1% by volume with respect to the initial liquid flow rate.

The turbidity of the neutralized final liquid obtained by the reaction of such a neutralization treatment was measured and found to be 104 NTU, and the turbidity could not be sufficiently reduced. The impurity load of the neutralized final solution was reduced by 84% with respect to the initial solution.

[Comparative Example 1]
In the neutralization treatment, the treatment was carried out in the same manner as in Example 1 except that the leachate residue slurry was not added.

The turbidity of the neutralization final liquid obtained by the reaction of such a neutralization treatment was measured and found to be 325 NTU, and the turbidity could not be sufficiently reduced.

<About the temperature of the starting liquid>
Next, the influence of the temperature of the neutralization treatment starting liquid (starting liquid) was investigated.

Specifically, in the neutralization step in the hydrometallurgical process of nickel oxide ore, a calcium carbonate slurry is added to the leachate as a neutralizing agent, and the pH of the neutralization final solution is 2.5 to 3.5. In addition to adjusting the range, the leaching residue slurry was added at a flow rate of 7.9% by volume with respect to the flow rate of the neutralization treatment starting liquid (leaching liquid) to perform the neutralization treatment. At this time, the temperature of the leachate was adjusted to about 54 ° C. to 66 ° C., and the effect of the temperature adjustment was confirmed.

The leachate, which is the starting solution for the neutralization treatment, has a nickel concentration of 2.3 g / L to 4.4 g / L, a cobalt concentration of 0.21 g / L to 0.45 g / L, and an iron concentration of 0.4 g / L to 1. A composition having a composition of .8 g / L, a zinc concentration of 0.05 g / L to 0.12 g / L, and a pH of 2.5 to 3.5 was used. The leaching residue slurry is obtained by solid-liquid separation of the leaching slurry obtained in the leaching step of the hydrometallurgical process while performing multi-stage washing, and has a nickel grade: 0.15% by mass or less, cobalt. The composition of grade: 0.02% by mass or less, iron grade: 48% by mass or more, and zinc grade: 0.02% by mass or less was used. In the neutralization treatment, when the leachate residue slurry was added, Polydadomac diluted 5-fold was used as a coagulant, and the ratio was 0.019% by volume to 0.029% by volume with respect to the starting solution of the neutralization treatment. Was added in the amount of addition.

The turbidity of the neutralized final liquid obtained by the reaction of such a neutralization treatment is measured using a turbidity measuring device (TB1000W, manufactured by Eutech), and the turbidity is as shown in the following formula. The turbidity reduction rate was calculated. The turbidity of the neutralization starting liquid was also measured in the same manner.
Turbidity reduction rate (%) = (turbidity of starting liquid-turbidity of neutralized final liquid) / turbidity of starting liquid x 100

Table 1 below also shows the neutralization treatment conditions of Test Examples 1 to 7, and the results of the turbidity and the turbidity reduction rate of the neutralization final solution.

As shown in Table 1, as the temperature in the neutralization treatment increased, the turbidity of the neutralization final liquid obtained by the neutralization treatment decreased, and the turbidity reduction rate increased. Specifically, it was found that the turbidity of the neutralized final solution was reduced to 100 NTU or less by setting the temperature to 54 ° C. or higher. In particular, by setting the temperature to 55 ° C. or higher, the turbidity reduction rate becomes 80% or higher, and the turbidity of the neutralized final liquid can be reduced more effectively. At a temperature of 63 ° C. or higher, the turbidity reduction rate does not improve much even if the temperature is raised, and the amount of heat energy used such as steam increases due to the temperature rise. Therefore, the temperature condition in the neutralization treatment is particularly 55. It was found that about ° C. to 63 ° C. was particularly preferable.

Claims (5)

A leaching step in which nickel oxide ore is leached with an acid to obtain a leaching slurry containing a leaching solution and a leaching residue, and a neutralizing agent is added to the leaching solution recovered by solid-liquid separation of the leaching slurry. A neutralization step of performing a sum treatment to obtain a neutralized starch containing impurities and a neutralized final solution containing nickel and cobalt, and a mixed sulfide of nickel and cobalt by adding a sulfide agent to the neutralized final solution. It is a neutralization treatment method of the neutralization step in the hydrometallurgical process of nickel oxide ore including the sulfide step of producing a substance.
A neutralizing agent is added to the leachate to adjust the pH in the range of 2.5 to 3.5, the temperature of the leachate is adjusted to 55 ° C. to 70 ° C., and the leachate slurry is solid-liquid separated. By adding the slurry of the obtained leachate residue at a flow rate of 7.0% by volume to 16.0% by volume with respect to the flow rate of the leachate, the turbidity of the neutralized final liquid obtained is less than 100 NTU. A neutralization treatment method for subjecting the neutralization final solution to the sulfide step while maintaining the turbidity of the final solution. The neutralization treatment method according to claim 1, wherein the leachate residue slurry has a slurry concentration of 1.5 t / m ³ to 1.7 t / m ³ . The neutralization treatment method according to claim 1 or 2 , wherein a coagulant is also added when the leachate residue slurry is added. The neutralization treatment method according to any one of claims 1 to 3 , wherein the leaching residue slurry is obtained by solid-liquid separation while performing multi-stage washing of the leaching slurry. A leaching step of subjecting nickel oxide ore with an acid to obtain a leaching slurry containing a leaching solution and a leaching residue, and adding a neutralizing agent to the leaching solution recovered by solid-liquid separation of the leaching slurry. A neutralization step of performing a sum treatment to obtain a neutralized starch containing impurities and a neutralized final solution containing nickel and cobalt, and a mixed sulfurization of nickel and cobalt by adding a sulfurizing agent to the neutralized final solution. A method for producing a mixed sulfide of nickel and cobalt, which comprises a sulfurization step of producing a substance.
A neutralizing agent is added to the leachate to adjust the pH in the range of 2.5 to 3.5, the temperature of the leachate is adjusted to 55 ° C. to 70 ° C., and the leachate slurry is solid-liquid separated. By adding the slurry of the obtained leachate at a flow rate of 7.0% by volume to 16.0% by volume with respect to the flow rate of the leachate, the turbidity of the obtained neutralized final liquid is less than 100 NTU. A method for producing a mixed sulfide of nickel and cobalt to be subjected to the sulfide step while maintaining the turbidity of the neutralized final liquid.

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